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Sample records for constructed horizontal wetlands
Horizontal subsurface flow constructed wetlands for mitigation of ...
The feasibility of using constructed wetlands (CWs) for the mitigation of pesticide runoff has been studied in the last decade. However, a lack of related data was verified when subsurface flow constructed wetlands (SSF CWs) are considered for this purpose. In the present work, SSF CWs were submitted to continuous ...
these systems can improve water quality, engineers and scientists construct systems that replicate the functions of natural wetlands. Constructed wetlands are treatment systems that use natural processes
Statistical Analysis of Nitrogen in the Soil of Constructed Wetland with Horizontal Sub-Surface Flow
Jakubaszek Anita
Full Text Available The removal of nitrogen compounds in constructed wetlands depends on various physical, chemical and biomechanical factors as well as on conditions of the environment. The paper presents the results of a statistical analysis of the depositing of nitrogen at HSSF (horizontal subsurface flow construcred wetland. The results of the substrate showed that the highest contents of nitrogen existed in the surface soil layer up to 20 cm of the depth. Nitrogen accumulation decreased in the deposit with depth, and in the direction of the wastewater flow.
Wastewater treatment in horizontal subsurface flow constructed wetlands using different media (setup stage
Abdel Razik A. Zidan
Full Text Available Wastewater treatment through horizontal subsurface flow (HSSF constructed wetlands (CWs using three different treatment media (gravel, pieces of plastic pipes, and shredded tire rubber chips were investigated in Samaha village, Dakahliya, Egypt. The study focused on the wetland setup stage during the first months of its operation (setup stage. In this stage media porosity, bacterial biofilm, and plant roots growth were in progress and it was prior to the operational steady state stage. Objectives of this paper are to study the change in media porosity of HSSF wetland cells in order to estimate duration of wetland setup stage, and to evaluate the use of different bed media on biological oxygen demand (BOD, chemical oxygen demand (COD and total suspended solids (TSS treatment. The results showed that after 180 days of operation, the wetland cells had reached steady porosity and had started stable treatment. Also performance of plastic media bed in pollutants reduction was better than gravel and rubber beds and gravel media was in advanced than rubber media.
Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW)
Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin; Anderson, Bruce; Cheng, Shuiping
Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg·L"−"1). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (Φ_P_S_I_I) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. - Highlights: • Physiological responses of the wetland plant to triazophos loads
Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Anderson, Bruce [Department of Civil Engineering, Queen' s University, Kingston K7L3N6 (Canada); Cheng, Shuiping, E-mail: shpcheng@tongji.edu.cn [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)
Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg·L{sup −1}). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (Φ{sub PSII}) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. - Highlights: • Physiological responses of the wetland plant to triazophos
Influence of chlorothalonil on the removal of organic matter in horizontal subsurface flow constructed wetlands.
Casas-Zapata, Juan C; Ríos, Karina; Florville-Alejandre, Tomás R; Morató, Jordi; Peñuela, Gustavo
This study investigates the effects of chlorothalonil (CLT) on chemical oxygen demand (COD) and dissolved organic carbon (DOC) in pilot-scale horizontal subsurface flow constructed wetlands (HSSFCW) planted with Phragmites australis. Physicochemical parameters of influent and effluent water samples, microbial population counting methods and statistical analysis were used to evaluate the influence of CLT on organic matter removal efficiency. The experiments were conducted on four planted replicate wetlands (HSSFCW-Pa) and one unplanted control wetland (HSSFCW-NPa). The wetlands exhibited high average organic matter removal efficiencies (HSSFCW-Pa: 80.6% DOC, 98.0% COD; HSSFCW-NPa: 93.2% DOC, 98.4% COD). The addition of CLT did not influence organic removal parameters. In all cases CLT concentrations in the effluent occurred in concentrations lower than the detection limit of the analytical method. Microbial population counts from HSSFCW-Pa showed significant correlations among different microbial groups and with different physicochemical variables. The apparent independence of organic matter removal and CLT inputs, along with the CLT depletion observed in effluent samples demonstrated that HSSFCW are a viable technology for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT.
Reconstruction of a constructed wetland with horizontal subsurface flow after 18 years of operation.
Hudcová, Tereza; Vymazal, Jan; Dunajský, Michal Kriška
The constructed wetland (CW) for 326 PE with horizontal subsurface flow at Koten�ice, Central Bohemia, Czech Republic, was built in 1994. Despite the relatively high efficiency of the CW, the filtration beds suffered from clogging, and therefore it was decided in 2011 to rebuild the whole system. The new treatment system was built as an experimental system consisting of four different combinations of horizontal and vertical beds. The major aim of the design was to determine the best hybrid combination which then could be used in the future for refurbishment of older horizontal flow CWs or for the new systems. The mechanical pretreatment consists of mechanical bar screens, a new Imhoff tank, and the original settling tank which has been converted into the accumulation tank from where the wastewater is pumped into the wetlands. The filters are planted with Phragmites australis, Phalaris arundinacea, Iris pseudacorus, Iris sibirica, Glyceria maxima and Lythrum salicaria in order to evaluate and compare various plant species' effect on the treatment process. The new technology includes a tertiary treatment which consists of a greenhouse with a photo-reactor for the cultivation of algae and hydroponic systems (residual nutrients removal), sludge reed-beds and a composting field.
Ibuprofen removal in horizontal subsurface flow constructed wetlands: treatment performance and fungal community dynamics.
Zhang, Dongqing; Luo, Jinxue; Lee, Zarraz May Ping; Gersberg, Richard M; Liu, Yu; Tan, Soon Keat; Ng, Wun Jern
The treatment performance of ibuprofen (IBP)-enriched wastewater by horizontal subsurface flow constructed wetlands planted with cattail (Typha angustifolia) and unplanted control mesocosms was investigated. Removal efficiencies of IBP were significantly (p fungal community in these wetland systems. The overall diversity of the fungal community was reduced under the IBP exposure. Taxonomic analysis revealed that 62.2% of the fungal sequences were affiliated with Basidiomycota, followed by Ascomycota (37.4%) at the phylum level. Uncultured fungus (48.2%), Chaetomium sp. (14.2%), Aspergillus sp. (12.4%), Trichoderma sp. (5.7%), Cladosporium sp. (5.4%), and Emericellopsis sp. (5.2%) were identified as dominant genera. At the genus level, a distinct profile of the fungal community in the IBP-enriched mesocosms was observed as compared to the control beds, and as well specific fungal genera were enhanced in the planted beds, regardless of IBP enrichment. However, despite these differences, the composition of the fungal community (as measured by Bray-Curtis similarity) was mostly unaffected by the significant IBP enrichment. On the other hand, a consistent similarity pattern of fungal community structure in the planted mesocosms suggests that the presence of higher macrophytes in the wetland systems may well help shape the fungal community structure.
Limestone and Zeolite as Alternative Media in Horizontal Subsurface Flow Constructed Wetlands: Laboratory-Scale Studies
Lizama, K.; Jaque, I.; Ayala, J.
Arsenic is well known for its chronic toxicity. Millions of people around the world are currently at risk, drinking water with As concentrations above 10 ppb, the WHO drinking water guideline. Although different treatment options exist, they are often limited by elevated costs and maintenance requirements. Constructed wetlands are a natural water treatment system, capable to remove metals and metalloids -including As- via different physical, chemical and biological processes. The use of alternative supporting media to enhance As removal in subsurface flow wetlands has been recommended, but not sufficiently studied. Limestone and zeolite have been identified as effective supporting media in subsurface flow wetlands aiming As removal. However, there are still key aspects to be addressed, such as the implications of using these media, the speciation in the solid phase, the role of vegetation, etc. This study investigated the performance of limestone and zeolite in three types of experiments: batch, column and as main supporting media in a bench scale horizontal subsurface flow wetland system. Synthetic water resembling a contaminated river in Chile (As concentration=3 mg/L, Fe concentration= 100 mg/L, pH=2) was used in all experiments. In the batch experiments, the As concentration, the mass of media and the contact time were varied. The column system consisted of three limestone columns and three zeolite columns, operated under a hydraulic loading of 20 mm/d. The wetland system consisted of twelve PVC cells: six filled with zeolite and six with limestone. Phragmites australis were planted in three cells of each media type, as control cells. From the batch experiments, maximum As sorption capacities as indicated by Langmuir model were 1.3 mg/g for limestone and 0.17 mg/g for zeolite, at 18 h contact time and 6.3 g/L medium concentration. EDS and XPS analyses revealed that As and Fe were retained in zeolite at the end of the batch experiments. Zeolite and limestone
Bacterial transformation and biodegradation processes simulation in horizontal subsurface flow constructed wetlands using CWM1-RETRASO.
Llorens, Esther; Saaltink, Maarten W; Poch, Manel; García, Joan
The performance and reliability of the CWM1-RETRASO model for simulating processes in horizontal subsurface flow constructed wetlands (HSSF CWs) and the relative contribution of different microbial reactions to organic matter (COD) removal in a HSSF CW treating urban wastewater were evaluated. Various different approaches with diverse influent configurations were simulated. According to the simulations, anaerobic processes were more widespread in the simulated wetland and contributed to a higher COD removal rate [72-79%] than anoxic [0-1%] and aerobic reactions [20-27%] did. In all the cases tested, the reaction that most contributed to COD removal was methanogenesis [58-73%]. All results provided by the model were in consonance with literature and experimental field observations, suggesting a good performance and reliability of CWM1-RETRASO. According to the good simulation predictions, CWM1-RETRASO is the first mechanistic model able to successfully simulate the processes described by the CWM1 model in HSSF CWs. Copyright © 2010 Elsevier Ltd. All rights reserved.
Treatment of high-strength wastewater in tropical constructed wetlands planted with Sesbania sesban: Horizontal subsurface flow versus vertical downflow
Dan, Truong Hoang; Quang, Le Nhat; Chiem, Nguyen Huu
Treatment of various types of wastewaters is an urgent problem in densely populated areas of many tropical countries. We studied the potential of using Sesbania sesban, an N2-fixing shrub, in constructed wetland systems for the treatment of high-strength wastewater. A replicated horizontal subsur...
Efficiency of a Horizontal Sub-Surface Flow Constructed Wetland Treatment System in an Arid Area
Abeer Albalawneh
Full Text Available The main objective of this study was to evaluate the performance and treatment efficiency of the Horizontal Sub-Surface Flow Constructed Wetland treatment system (HSF-CW in an arid climate. Seventeen sub-surface, horizontal-flow HSF-CW units have been operated for approximately three years to improve the quality of partially-treated municipal wastewater. The studied design parameters included two sizes of volcanic tuff media (i.e., fine or coarse, two different bed dimensions (i.e., long and short, and three plantation types (i.e., reed, kenaf, or no vegetation as a control. The effluent Biological Oxygen Demand (BOD5, Chemical Oxygen Demand (COD, Total Suspended Solid (TSS, and phosphorus from all of the treatments were significantly lower as compared to the influent and demonstrated a removal efficiency of 55%, 51%, 67%, and 55%, respectively. There were significant increases in Electrical Conductivity (EC, sulfate, and calcium in the effluent of most HSF-CWs due to evaporative concentration and mineral dissolution from the media. The study suggests that unplanted beds with either fine or coarse media are the most suitable combinations among all of the studied designs based on their treatment efficiency and less water loss in arid conditions.
Determination and removal of antibiotics in secondary effluent using a horizontal subsurface flow constructed wetland.
Zhang, Chunhui; Ning, Ke; Zhang, Wenwen; Guo, Yuanjie; Chen, Jun; Liang, Chen
Increased attention is currently being directed towards the potential negative effects of antibiotics and other PPCPs discharged into the aquatic environment via municipal WWTP secondary effluents. A number of analytical methods, such as high performance liquid chromatography technologies, including a high performance liquid chromatography-fluorescence method (HPLC-FLD), high performance liquid chromatography-UV detection method (HPLC-UV) and high performance liquid chromatography-mass spectrometry method (HPLC-MS), have been suggested as determination technologies for antibiotic residues in water. In this study, we implement a HPLC-MS/MS combined method to detect and analyze antibiotics in WWTP secondary effluent and apply a horizontal subsurface flow constructed wetland (CW) as an advanced wastewater treatment for removing antibiotics in the WWTP secondary effluent. The results show that there were 2 macrolides, 2 quinolones and 5 sulfas in WWTP secondary effluent among all the 22 antibiotics considered. After the CW advanced treatment, the concentration removal efficiencies and removal loads of 9 antibiotics were 53-100% and 0.004-0.7307 μg m(-2) per day, respectively.
Treatment of landfill leachate using an aerated, horizontal subsurface-flow constructed wetland.
Nivala, J; Hoos, M B; Cross, C; Wallace, S; Parkin, G
A pilot-scale subsurface-flow constructed wetland was installed at the Jones County Municipal Landfill, near Anamosa, Iowa, in August 1999 to demonstrate the use of constructed wetlands as a viable low-cost treatment option for leachate generated at small landfills. The system was equipped with a patented wetland aeration process to aid in removal of organic matter and ammonia nitrogen. The high iron content of the leachate caused the aeration system to cease 2 years into operation. Upon the installation of a pretreatment chamber for iron removal and a new aeration system, treatment efficiencies dramatically improved. Seasonal performance with and without aeration is reported for 5-day biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), ammonia nitrogen (NH(4)-N), and nitrate nitrogen (NO(3)-N). Since winter air temperatures in Iowa can be very cold, a layer of mulch insulation was installed on top of the wetland bed to keep the system from freezing. When the insulation layer was properly maintained (either through sufficient litterfall or replenishing the mulch layer), the wetland sustained air temperatures of as low as -26 degrees C without freezing problems.
Treatment of fishpond water by recirculating horizontal and vertical flow constructed wetlands in the tropics
Konnerup, Dennis; Trang, Ngo Thuy Diem; Brix, Hans
quantities of phytoplankton algae were removed in the CWs but abundance of toxic algae such as Microcystis was low. It is concluded that particularly vertical flow CWs have great potential for treatment of fishpond water in recirculating aquaculture systems in the tropics as the discharge of polluted water......Common practice of aquaculture in Vietnam and other countries in South East Asia involves frequent discharge of polluted water into rivers which results in eutrophication and degradation of receiving water bodies. There is therefore a need to develop improved aquaculture systems which have a more...... efficient use of water and less environmental impact. The aim of this study was to assess the suitability of using constructed wetlands (CWs) for the treatment of fishpond water in a recirculating aquaculture system in the Mekong Delta of Vietnam. Water from a fishpond stocked with Nile tilapia (Oreochromis...
Effect of physico-chemical pretreatment on the removal efficiency of horizontal subsurface-flow constructed wetlands
Caselles-Osorio, Aracelly [Environmental Engineering Division, Hydraulics, Coastal and Environmental Engineering Department, Technical University of Catalonia, c/Jordi Girona 1-3, Modul D-1, 08034 Barcelona (Spain); Department of Biology, Atlantic University, Km 7 Higway Old Colombia Port, Barranquilla (Colombia); Garcia, Joan [Environmental Engineering Division, Hydraulics, Coastal and Environmental Engineering Department, Technical University of Catalonia, c/Jordi Girona 1-3, Modul D-1, 08034 Barcelona (Spain)]. E-mail: joan.garcia@upc.edu
In this study, we tested the effect of a physico-chemical pretreatment on contaminant removal efficiency in two experimental horizontal subsurface-flow constructed wetlands (SSF CWs). One SSF CW was fed with settled urban wastewater, whereas the other with the same wastewater after it had undergone a physico-chemical pretreatment. The SSF CWs were operated with three different hydraulic retention times. During the experiments the effluent concentrations of COD, ammonia N and sulfate were very similar, and, therefore, the physico-chemical pretreatment did not improve the quality of the effluents. COD removal efficiency (as percentage or mass surface removal rate) was slightly greater in the SSF CW fed with pretreated wastewater. Ammonia N removal efficiency was, in general, similar in both SSF CWs and very high (80-90%). At the end of the experiments it was observed that in the SSF CW fed with settled wastewater the hydraulic conductivity decreased by a 20%. - A physico-chemical pretreatment may help to reduce the risk of clogging of subsurface-flow constructed wetlands.
Caselles-Osorio, Aracelly; Garcia, Joan
In this study, we tested the effect of a physico-chemical pretreatment on contaminant removal efficiency in two experimental horizontal subsurface-flow constructed wetlands (SSF CWs). One SSF CW was fed with settled urban wastewater, whereas the other with the same wastewater after it had undergone a physico-chemical pretreatment. The SSF CWs were operated with three different hydraulic retention times. During the experiments the effluent concentrations of COD, ammonia N and sulfate were very similar, and, therefore, the physico-chemical pretreatment did not improve the quality of the effluents. COD removal efficiency (as percentage or mass surface removal rate) was slightly greater in the SSF CW fed with pretreated wastewater. Ammonia N removal efficiency was, in general, similar in both SSF CWs and very high (80-90%). At the end of the experiments it was observed that in the SSF CW fed with settled wastewater the hydraulic conductivity decreased by a 20%. - A physico-chemical pretreatment may help to reduce the risk of clogging of subsurface-flow constructed wetlands
A novel horizontal subsurface flow constructed wetland: Reducing area requirements and clogging risk.
Tatoulis, Triantafyllos; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Vayenas, Dimitrios V; Stefanakis, Alexandros I
The use of Constructed Wetlands (CWs) has been nowadays expanded from municipal to industrial and agro-industrial wastewaters. The main limitations of CWs remain the relatively high area requirements compared to mechanical treatment technologies and the potential occurrence of the clogging phenomenon. This study presents the findings of an innovative CW design where novel materials were used. Four pilot-scale CW units were designed, built and operated for two years. Each unit consisted of two compartments, the first of which (two thirds of the total unit length) contained either fine gravel (in two units) or random type high density polyethylene (HDPE) (in the other two units). This plastic media type was tested in a CW system for the first time. The second compartment of all four units contained natural zeolite. Two units (one with fine gravel and one with HDPE) were planted with common reeds, while the other two were kept unplanted. Second cheese whey was introduced into the units, which were operated under hydraulic residence times (HRT) of 2 and 4 days. After a two-year operation and monitoring period, pollutant removal rates were approximately 80%, 75% and 90% for COD, ammonium and ortho-phosphate, respectively, while temperature and HRT had no significant effect on pollutant removal. CWs containing the plastic media achieved the same removal rates as those containing gravel, despite receiving three times higher hydraulic surface loads (0.08 m/d) and four times higher organic surface loads (620 g/m 2 /d). This reveals that the use of HDPE plastic media could reduce CW surface area requirements by 75%. Copyright © 2017 Elsevier Ltd. All rights reserved.
Phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia in a horizontal subsurface flow constructed wetland.
Li, Yifei; Zhang, Jiefeng; Zhu, Guibing; Liu, Yu; Wu, Bing; Ng, Wun Jern; Appan, Adhityan; Tan, Soon Keat
Widespread occurrence of trace pharmaceutical residues in aquatic environments is of great concerns due to the potential chronic toxicity of certain pharmaceuticals including ibuprofen on aquatic organisms even at environmental levels. In this study, the phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia were investigated in a horizontal subsurface flow constructed wetland system. The experimental wetland system consisted of a planted bed with Typha angustifolia and an unplanted bed (control) to treat ibuprofen-loaded wastewater (∼107.2 μg L(-1)). Over a period of 342 days, ibuprofen was accumulated in leaf sheath and lamina tissues at a mean concentration of 160.7 ng g(-1), indicating the occurrence of the phytoextraction of ibuprofen. Root-uptake ibuprofen was partially transformed to ibuprofen carboxylic acid, 2-hydroxy ibuprofen and 1-hydroxy ibuprofen which were found to be 1374.9, 235.6 and 301.5 ng g(-1) in the sheath, respectively, while they were 1051.1, 693.6 and 178.7 ng g(-1) in the lamina. The findings from pyrosequencing analysis of the rhizosphere bacteria suggest that the Dechloromonas sp., the Clostridium sp. (e.g. Clostridium saccharobutylicum), the order Sphingobacteriales, and the Cytophaga sp. in the order Cytophagales were most probably responsible for the rhizodegradation of ibuprofen. Copyright © 2016 Elsevier Ltd. All rights reserved.
Design configurations affecting flow pattern and solids accumulation in horizontal free water and subsurface flow constructed wetlands.
Pedescoll, A; Sidrach-Cardona, R; Sánchez, J C; Carretero, J; Garfi, M; Bécares, E
The aim of this study was to evaluate the effect of different horizontal constructed wetland (CW) design parameters on solids distribution, loss of hydraulic conductivity over time and hydraulic behaviour, in order to assess clogging processes in wetlands. For this purpose, an experimental plant with eight CWs was built at mesocosm scale. Each CW presented a different design characteristic, and the most common CW configurations were all represented: free water surface flow (FWS) with different effluent pipe locations, FWS with floating macrophytes and subsurface flow (SSF), and the presence of plants and specific species (Typha angustifolia and Phragmites australis) was also considered. The loss of the hydraulic conductivity of gravel was greatly influenced by the presence of plants and organic load (representing a loss of 20% and c.a. 10% in planted wetlands and an overloaded system, respectively). Cattail seems to have a greater effect on the development of clogging since its below-ground biomass weighed twice as much as that of common reed. Hydraulic behaviour was greatly influenced by the presence of a gravel matrix and the outlet pipe position. In strict SSF CW, the water was forced to cross the gravel and tended to flow diagonally from the top inlet to the bottom outlet (where the inlet and outlet pipes were located). However, when FWS was considered, water preferentially flowed above the gravel, thus losing half the effective volume of the system. Only the presence of plants seemed to help the water flow partially within the gravel matrix. Copyright © 2012 Elsevier Ltd. All rights reserved.
Nitrogen Removal in a Horizontal Subsurface Flow Constructed Wetland Estimated Using the First-Order Kinetic Model
Lijuan Cui
Full Text Available We monitored the water quality and hydrological conditions of a horizontal subsurface constructed wetland (HSSF-CW in Beijing, China, for two years. We simulated the area-based constant and the temperature coefficient with the first-order kinetic model. We examined the relationships between the nitrogen (N removal rate, N load, seasonal variations in the N removal rate, and environmental factors—such as the area-based constant, temperature, and dissolved oxygen (DO. The effluent ammonia (NH4+-N and nitrate (NO3−-N concentrations were significantly lower than the influent concentrations (p < 0.01, n = 38. The NO3−-N load was significantly correlated with the removal rate (R2 = 0.96, p < 0.01, but the NH4+-N load was not correlated with the removal rate (R2 = 0.02, p > 0.01. The area-based constants of NO3−-N and NH4+-N at 20 °C were 27 ± 26 (mean ± SD and 14 ± 10 m∙year−1, respectively. The temperature coefficients for NO3−-N and NH4+-N were estimated at 1.004 and 0.960, respectively. The area-based constants for NO3−-N and NH4+-N were not correlated with temperature (p > 0.01. The NO3−-N area-based constant was correlated with the corresponding load (R2 = 0.96, p < 0.01. The NH4+-N area rate was correlated with DO (R2 = 0.69, p < 0.01, suggesting that the factors that influenced the N removal rate in this wetland met Liebig's law of the minimum.
Effect of multilayer substrate configuration in horizontal subsurface flow constructed wetlands: assessment of treatment performance, biofilm development, and solids accumulation.
Ding, Yanli; Lyu, Tao; Bai, Shaoyuan; Li, Zhenling; Ding, Haijing; You, Shaohong; Xie, Qinglin
This study investigates the influence of multilayer substrate configuration in horizontal subsurface flow constructed wetlands (HSCWs) on their treatment performance, biofilm development, and solids accumulation. Three pilot-scale HSCWs were built to treat campus sewage and have been operational for 3Â years. The HSCWs included monolayer (CW1), three-layer (CW3), and six-layer (CW6) substrate configurations with hydraulic conductivity of the substrate increasing from the surface to bottom in the multilayer CWs. It was demonstrated the pollutant removal performance after a 3-year operation improved in the multilayer HSCWs (49-80%) compared to the monolayer HSCW (29-41%). Simultaneously, the multilayer HSCWs exhibited significant features that prevented clogging compared to the monolayer configuration. The amount of accumulated solids was notably higher in the monolayer CW compared to multilayer CWs. Further, multilayer HSCWs could delay clogging by providing higher biofilm development for organics removal and consequently, lesser solids accumulations. Principal component analysis strongly supported the visualization of the performance patterns in the present study and showed that multilayer substrate configuration, season, and sampling locations significantly influenced biofilm growth and solids accumulation. Finally, the present study provided important information to support the improved multilayer configured HSCW implication in the future.
Assessing the efficiency of an unplanted horizontal flow constructed wetland to reduce some emerging organic micropollutants. Preliminary results
Tapias, Josefina C.; Vila, Marta; Himi, Mahjoub; Salvadó, Victoria; Casas, Albert; Hidalgo, Manuela
The presence of emerging organic contaminants (EOC) such as pharmaceutical and personal care products, pesticides or antiseptics in wastewater is an increasing concern worldwide due to their potential toxicological effects for humans and other living organisms. Because of their low concentration and persistence their removal using conventional treatment technologies is often incomplete and for this reason there is a growing interest for assessing the efficiency of alternative wastewater treatment technologies such as constructed wetlands (CWs). CWs are engineered systems for wastewater treatment plant (WWTP) designed to take advantage of many of the same processes that occur in natural wetlands, but within a more controlled environment. CWs are a cost-effective alternative to conventional wastewater treatment plants especially in the context of small communities with less than 2000 people equivalent. Our study has been conducted at the Verdú WWTP (Lleida, Catalonia, NE Spain). This system has a primary treatment consisting on three septic tanks in parallel with a volume of 50 m3 and three chambers each one. The primary effluent is distributed to four parallel horizontal subsurface flow (HSSF) CWs. Originally the system was planted with common reed (Phragmites australis), but currently after twelve years of service the system show evidences of clogging and then gravel bed was replaced and plants removed. After the HSSF CWs, there are two wastewater stabilization ponds (WSPs) followed by two smaller polishing horizontal HSSF CWs. Excellent overall treatment performance was exhibited on the elimination of conventional water quality parameters (93-98% average removal efficiency for TSS, COD, BOD5 and NTK), and its final effluent proved to comply with existing Spanish guidelines. Sampling has been conducted along two years at different seasons and examined EOC substances included analgesic and anti-inflammatory drugs (ibuprofen, diclofenac, and naproxene
Nitrogen removal and its relationship with the nitrogen-cycle genes and microorganisms in the horizontal subsurface flow constructed wetlands with different design parameters.
Chen, Jun; Ying, Guang-Guo; Liu, You-Sheng; Wei, Xiao-Dong; Liu, Shuang-Shuang; He, Liang-Ying; Yang, Yong-Qiang; Chen, Fan-Rong
This study aims to investigate nitrogen removal and its relationship with the nitrogen-cycle genes and microorganisms in the horizontal subsurface flow constructed wetlands (CWs) with different design parameters. Twelve mesocosm-scale CWs with four substrates and three hydraulic loading rates were set up in the outdoor. The result showed the CWs with zeolite as substrate and HLR of 20Â cm/d were selected as the best choice for the TN and NH 3 -N removal. It was found that the single-stage mesocosm-scale CWs were incapable to achieve high removals of TN and NH 3 -N due to inefficient nitrification process in the systems. This was demonstrated by the lower abundance of the nitrification genes (AOA and AOB) than the denitrification genes (nirK and nirS), and the less diverse nitrification microorganisms than the denitrification microorganisms in the CWs. The results also show that microorganism community structure including nitrogen-cycle microorganisms in the constructed wetland systems was affected by the design parameters especially the substrate type. These findings show that nitrification is a limiting factor for the nitrogen removal by CWs.
Constructed wetlands : the Canadian context
Speer, S.; Champagne, P. [Queen' s Univ., Kingston, ON (Canada). Dept. of Civil Engineering
Large volumes of wastewater from livestock and production facilities must be treated to minimize the contamination of waterways in agricultural areas. This paper investigated the use of constructed wetlands as a lower-cost and efficient method of treating agricultural wastewaters. The study found that while constructed wetlands required limited maintenance, temperature dependency of the constructed wetlands systems is a limiting factor in their widespread implementation. Lower operating temperatures are only overcome by constructing larger wetlands systems, which require a substantial amount of land. The Canadian climate poses significant challenges to the implementation of constructed wetlands, which become inoperative during winter months. Plants and bacteria normally become dormant or die during winter months, which can create a lag in wetland treatment during the initial months of operation in the Spring. Snowmelt and added rainfall in the Spring can also create a high flow within the wetland cells, as many constructed wetlands rely on runoff as a feed source. Washout of bacteria can occur. Wastewater storage systems or further engineering of the wetlands may be required. It was concluded that insulating wetland cells will maintain a warmer operating temperature, while the addition of an aeration system will increase the treatment efficiency of the wetland during winter months. 17 refs., 5 tabs., 2 figs.
Domestic Wastewater Depuration Using a Horizontal Subsurface Flow Constructed Wetland and Theoretical Surface Optimization: A Case Study under Dry Mediterranean Climate
Pedro Andreo-Martínez
Full Text Available The wastewater generated by isolated houses without access to public sewers can cause environmental problems, like the contamination of aquifers with nitrates and phosphates, as occurs in southeastern Spain. The effectiveness of a previously built horizontal subsurface flow constructed wetland (HF-CW was studied over two years as a possible solution. This HF-CW measured 27 m2; it was planted with Phragmites australis(Cav. Trin. Ex Steuds sp. Altissima and the parameters studied were those required by European Union (EU legislation and adopted by Spain. Average abatement ef�ciency rates, for the �rst and the second year of study, were: biochemical oxygen demand over �ve days (BOD5 (96.4%, 92.0%, chemical oxygen demand (COD (84.6%, 77.7%, total suspended solids(TSS (94.8%,89.9%,total nitrogen(TN(79.5%,66.0%,ammonium nitrogen(NH4+-N(98.8%, 86.6% and total phosphorous (TP (83.7%, 82.8%. Average abatement ef�ciency for nitrate nitrogen (NO3−-N (−1280.5%, −961.1% and nitrite nitrogen (NO2−-N (−5.8%, −40.0% were negative because its content in influent wastewater was very low and they appear mainly from influent NH4+-N, as a result of puri�cation processes carried out in the HF-CW bed. The abatement rates make the system suitable to produce discharges into the environment in accordance with Spanish law. It is noteworthy that the HF-CW patch suffered an episode of bed drying during the summer of 2013, whereby the causes were related to system oversizing and high evapotranspiration in the area. As a consequence, the decrease in the abatement of water pollutants during the second year can be attributed to the creation of preferential water flow paths and short circuits through the constructed wetland (CW bed. As a result of the oversizing of the CW, a theoretical resizing based on BOD5, TSS, TN or TP is proposed. The calculated values for the redesign were: 5.22 m2 considering DBO5, 0.18 m2 considering TSS, 10.14 m2 considering
Hydrocarbon removal with constructed wetlands
Eke, Paul Emeka
Wetlands have long played a significant role as natural purification systems, and have been effectively used to treat domestic, agricultural and industrial wastewater. However, very little is known about the biochemical processes involved, and the use of constructed treatment wetlands in the removal of petroleum aromatic hydrocarbons from produced and/or processed water. Wastewaters from the oil industry contain aromatic hydrocarbons such as benzene, toluene, ethylbenzene and x...
Investigation into the kinetics of constructed wetland degradation ...
-scale, horizontal subsurface-flow constructed wetland (6.0 m × 1.0 m × 0.5 m) in Leipzig, Germany. The bed contained glacial gravel (4–8 mm) planted with Phragmites australis. Construction was completed in October 2013 and experiments ...
Removal Efficiency of Constructed Wetland for Treatment of Agricultural Wastewaters
Michal Šereš
Full Text Available This study describes performance of a hybrid constructed wetland (CW for treating wastewater from small farm in Czech Republic. The CW consisting of two horizontal filters, one vertical filter and three shallow pondsand reduced inflow values of 25.400 mg/L COD and 2.640 mg/L BOD5 by up to 99%.
Fate of estrone in laboratory-scale constructed wetlands
A horizontal, subsurface, laboratory-scale constructed wetland (CW) consisting of four cells in series was used to determine the attenuation of the steroid hormone estrone (E1) present in animal wastewater. Liquid swine manure diluted 1:80 with farm pond water and dosed with [14C]E1 flowed through ...
Šereš, M.; Hnátková, T.; Vymazal, J.; Vaněk, Tomáš
Ro�. 12, �. 1 (2017), s. 45-52 ISSN 1857-1727 R&D Projects: GA TA ČR TA01020573 Institutional support: RVO:61389030 Keywords : Agriculture wastewater * Constructed wetland * Horizontal filter * Hybrid system s * Vertical filter Subject RIV: DJ - Water Pollution ; Quality OBOR OECD: Bioremediation, diagnostic biotechnologies (DNA chips and biosensing devices) in environmental management
Treatment of wastewater with the constructed wetland
Fernandez, R.; Olivares, S.
Constructed wetland is an environmental sound, actual and economic solution for the treatment of wastewater. The use of these constructed wetlands increased in the last few years, principally in developed countries. However there is not much information about the performance of these biological systems in tropical and subtropical climates. In these review the state of art of these technology is given, and also the advantage of the use of the constructed wetland for the wastewater treatment in our country
Process-Based Modeling of Constructed Wetlands
Baechler, S.; Brovelli, A.; Rossi, L.; Barry, D. A.
Constructed wetlands (CWs) are widespread facilities for wastewater treatment. In subsurface flow wetlands, contaminated wastewater flows through a porous matrix, where oxidation and detoxification phenomena occur. Despite the large number of working CWs, system design and optimization are still mainly based upon empirical equations or simplified first-order kinetics. This results from an incomplete understanding of the system functioning, and may in turn hinder the performance and effectiveness of the treatment process. As a result, CWs are often considered not suitable to meet high water quality-standards, or to treat water contaminated with recalcitrant anthropogenic contaminants. To date, only a limited number of detailed numerical models have been developed and successfully applied to simulate constructed wetland behavior. Among these, one of the most complete and powerful is CW2D, which is based on Hydrus2D. The aim of this work is to develop a comprehensive simulator tailored to model the functioning of horizontal flow constructed wetlands and in turn provide a reliable design and optimization tool. The model is based upon PHWAT, a general reactive transport code for saturated flow. PHWAT couples MODFLOW, MT3DMS and PHREEQC-2 using an operator-splitting approach. The use of PHREEQC to simulate reactions allows great flexibility in simulating biogeochemical processes. The biogeochemical reaction network is similar to that of CW2D, and is based on the Activated Sludge Model (ASM). Kinetic oxidation of carbon sources and nutrient transformations (nitrogen and phosphorous primarily) are modeled via Monod-type kinetic equations. Oxygen dissolution is accounted for via a first-order mass-transfer equation. While the ASM model only includes a limited number of kinetic equations, the new simulator permits incorporation of an unlimited number of both kinetic and equilibrium reactions. Changes in pH, redox potential and surface reactions can be easily incorporated
Effects of interspecific competition on the growth of macrophytes and nutrient removal in constructed wetlands: A comparative assessment of free water surface and horizontal subsurface flow systems.
Zheng, Yucong; Wang, Xiaochang; Dzakpasu, Mawuli; Zhao, Yaqian; Ngo, Huu Hao; Guo, Wenshan; Ge, Yuan; Xiong, Jiaqing
The outcome of competition between adjoining interspecific colonies of Phragmites and Typha in two large field pilot-scale free water surface (FWS) and subsurface flow (SSF) CWs is evaluated. According to findings, the effect of interspecific competition was notable for Phragmites australis, whereby it showed the highest growth performance in both FWS and SSF wetland. In a mixed-culture, P. australis demonstrates superiority in terms of competitive interactions for space between plants. Furthermore, the interspecific competition among planted species seemed to cause different ecological responses of plant species in the two CWs. For example, while relatively high density and shoot height determined the high aboveground dry weight of P. australis in the FWS wetland, this association was not evident in the SSF. Additionally, while plants nutrients uptake accounts for a higher proportion of the nitrogen removal in FWS, that in the SSF accounts for a higher proportion of the phosphorous removal. Copyright © 2016 Elsevier Ltd. All rights reserved.
Bioremediation of arsenic (As from mine effluent by a horizontal flow constructed wetland: A case study in largest borax reserve area in over the world, Kırka, Eskişehir
Onur Can Türker
Full Text Available In this study, a horizontal flow constructed wetland (HFCW planted with Typha angustifolia, was tested to bioremediation potential for arsenic from mine effluent under the natural climatic conditions in largest boron mine reserve area over the world, Kırka (Eskişehir. Briefly, the objective of the present experiment was to investigate arsenic bioremediation capability of wetland system and asses the phytoremediation efficiency of T. angustifolia, selected as a donor plant in this study, with different initial arsenic concentrations. Our results indicated that HFCW has capability to decreased arsenic in mine effluent from 49 µg L-1 to 21.8 µg L-1 in a period of 84 days, suggesting that HFCW could be a reasonable bio-filter option to control arsenic pollution directly from mining effluent in largest borax reserve over the world. Furthermore, we found that arsenic concentration in outflow samples was stably below 10 µg L-1 (drinking water safety limit with an inflow range from 42.3 to 42.1 arsenic µg L-1 during the first 28 days. Our results also indicated that belowground parts of T.angustifolia accumulate more arsenic from mine effluent compared to aboveground parts during experiment period. Therefore, we suggested that belowground parts of the plants in HFCW play an important role for arsenic bioremediation from mine effluent which origin of Kırka Borax reserve area. In this respect, bioconcentration factor (BCF for the plants which grown in HFCW was found higher than those of control group. Moreover, results of the present experiment also showed that relatively high level of arsenic retained in the filtration media of HFCW during the experiment period, indicating that filtration media which was used in HFCW has potential to filter arsenic from mine effluent. Consequently, the scientific insight of the present study is to present an innovative, cost effective, and easy operating method for arsenic remediation from mine effluent.
Pesticide mitigation capacities of constructed wetlands
Matthew T. Moore; Charles M. Cooper; Sammie Smith; John H. Rodgers
This research focused on using constructed wetlands along field perimeters to buffer receiving water against potential effects of pesticides associated with storm runoff. The current study incorporated wetland mesocosm sampling following simulated runoff events using chlorpyrifos, atrazine, and metolachlor. Through this data collection and simple model analysis,...
An assessment of the performance of municipal constructed wetlands in Ireland.
Hickey, Anthony; Arnscheidt, Joerg; Joyce, Eadaoin; O'Toole, James; Galvin, Gerry; O' Callaghan, Mark; Conroy, Ken; Killian, Darran; Shryane, Tommy; Hughes, Francis; Walsh, Katherine; Kavanagh, Emily
While performance assessments of constructed wetlands sites around the world have appraised their capacity for effective removal of organics, a large variance remains in these sites' reported ability to retain nutrients, which appears to depend on differences in design, operation and climate factors. Nutrient retention is a very important objective for constructed wetlands, to avoid eutrophication of aquatic environments receiving their effluents. This study assessed the performance of constructed wetlands in terms of nutrient retention and associated parameters under the humid conditions of Ireland's temperate maritime climate. A review of the performance of 52 constructed wetland sites from 17 local authorities aimed to identify the best performing types of constructed wetlands and the treatment factors determining successful compliance with environmental standards. Data analysis compared effluent results from constructed wetlands with secondary free surface flow or tertiary horizontal subsurface flow, hybrid systems and integrated constructed wetlands with those from small-scale mechanical wastewater treatment plants of the same size class. Nutrient concentrations in effluents of constructed wetlands were negatively correlated (p treatment performance of constructed wetlands significantly (p wastewater treatment plants, secondary free surface water and tertiary horizontal subsurface flow wetlands showed a very large variance in effluent concentrations for organic and nutrient parameters. E. coli numbers in effluents were lowest for integrated constructed wetlands with an arithmetic mean of 89 MPN/100 ml. Despite Ireland's humid climate, some constructed wetland sites achieved long or frequent periods of zero effluent discharge and thus did not transfer any waterborne pollution to their receptors during these periods. Copyright © 2018 Elsevier Ltd. All rights reserved.
Retention and distribution of Cu, Pb, Cr, and Zn in a full-scale hybrid constructed wetland receiving municipal sewage
Xiao, H.W.; Zhang, S.L.; Zhai, J.; He, Q.; Mels, A.R.; Ning, K.J.; Liu, J.
This study was conducted to investigate the retention and distribution of Cu, Pb, Cr, and Zn in a hybrid constructed wetland (CW) that consists of both vertical baffled flow wetlands (VBFWs) and horizontal subsurface flow wetlands (HSSFs) with unique flow regimes and oxygen distribution. The heavy
Removal of nutrients from septic tank effluent with baffle subsurface-flow constructed wetlands
Lihu Cui; Ying Ouyang; Weizhi Yang; Zhujian Huang; Qiaoling Xu; Guangwei Yu
Three new baffle flow constructed wetlands (CWs), namely the baffle horizontal flow CW (Z1), baffle vertical flow CW (Z2) and baffle hybrid flow CW (Z3), along with one traditional horizontal subsurface flow CW (Z4) were designed to test the removal efficiency of nitrogen (N) and phosphorus (P) from the septic tank effluent under varying hydraulic retention times (HRTs...
Constructed wetlands for wastewater treatment: five decades of experience.
Vymazal, Jan
The first experiments on the use of wetland plants to treat wastewaters were carried out in the early 1950s by Dr. Käthe Seidel in Germany and the first full-scale systems were put into operation during the late 1960s. Since then, the subsurface systems have been commonly used in Europe while free water surface systems have been more popular in North America and Australia. During the 1970s and 1980s, the information on constructed wetland technology spread slowly. But since the 1990 s the technology has become international, facilitated by exchange among scientists and researchers around the world. Because of the need for more effective removal of ammonia and total nitrogen, during the 1990 s and 2000s vertical and horizontal flow constructed wetlands were combined to complement each other to achieve higher treatment efficiency. Today, constructed wetlands are recognized as a reliable wastewater treatment technology and they represent a suitable solution for the treatment of many types of wastewater.
Paracetamol removal in subsurface flow constructed wetlands
Ranieri, Ezio; Verlicchi, Paola; Young, Thomas M.
SummaryIn this study two pilot scale Horizontal Subsurface Flow Constructed Wetlands (HSFCWs) near Lecce, Italy, planted with different macrophytes ( Phragmites australis and Typha latifolia) and an unplanted control were assessed for their effectiveness in removing paracetamol. Residence time distributions (RTDs) for the two beds indicated that the Typha bed was characterized by a void volume fraction (porosity) of 0.16 and exhibited more ideal plug flow behavior (Pe = 29.7) than the Phragmites bed (Pe = 26.7), which had similar porosity. The measured hydraulic residence times in the planted beds were 35.8 and 36.7 h when the flow was equal to 1 m 3/d. The Phragmites bed exhibited a range of paracetamol removals from 51.7% for a Hydraulic Loading Rate (HLR) of 240 mm/d to 87% with 120 mm/d HLR and 99.9% with 30 mm/d. The Typha bed showed a similar behavior with percentages of removal slightly lower, ranging from 46.7% (HLR of 240 mm/d) to >99.9% (hydraulic loading rate of 30 mm/d). At the same HLR values the unplanted bed removed between 51.3% and 97.6% of the paracetamol. In all three treatments the paracetamol removal was higher with flow of 1 m 3/d and an area of approx. 7.5 m 2 (half bed) than in the case of flow equal to 0.5 m 3/d with a surface treatment of approx. 3.75 m 2. A first order model for paracetamol removal was evaluated and half lives of 5.16 to 10.2 h were obtained.
Analysis of chemical reaction kinetics of depredating organic pollutants from secondary effluent of wastewater treatment plant in constructed wetlands.
Wang, Hao; Jiang, Dengling; Yang, Yong; Cao, Guoping
Four subsurface constructed wetlands were built to treat the secondary effluent of a wastewater treatment plant in Tangshan, China. The chemical pollutant indexes of chemical oxygen demand (COD) were analyzed to evaluate the removal efficiency of organic pollutants from the secondary effluent of the wastewater treatment plant. In all cases, the subsurface constructed wetlands were efficient in treating organic pollutants. Under the same hydraulic loading condition, the horizontal flow wetlands exhibited better efficiency of COD removal than vertical flow wetlands: the removal rates in horizontal flow wetlands could be maintained at 68.4 ± 2.42% to 92.2 ± 1.61%, compared with 63.8 ± 1.19% to 85.0 ± 1.25% in the vertical flow wetlands. Meanwhile, the chemical reaction kinetics of organic pollutants was analyzed, and the results showed that the degradation courses of the four subsurface wetlands all corresponded with the first order reaction kinetics to a large extent.
Tratamento de esgotos sanitários em sistemas reatores UASB/wetlands construídas de fluxo horizontal: eficiência e estabilidade de remoção de matéria orgânica, sólidos, nutrientes e coliformes Domestic wastewater treatment in UASB-horizontal flow constructed wetlands systems: organic matter, solids, nutrients and coliforms removal
Maria Lúcia Calijuri
Full Text Available Este trabalho apresentou os resultados de um estudo realizado durante 19 meses sobre o comportamento de wetlands construídas na remoção de matéria orgânica, sólidos, nutrientes e coliformes, em unidades em escala piloto de fluxo horizontal, subsuperficial e superficial, com tempo de detenção hidráulica entre 1,3 a 5,3 dias, operando como pós-tratamento de efluentes de reatores UASB (esgotos sanitários. A remoção de matéria orgânica e de sólidos mostrou-se elevada e estável, com eficiências médias de 70, 80 e 60% para SST, DBO5 e DQO, respectivamente. A remoção de nutrientes, após início promissor, mostrou-se instável e aparentemente influenciada pela temperatura. O sistema de tratamento revelou elevado potencial de remoção de coliformes, embora com variações relativamente amplas ao longo do período de operação: ≈ 2 log10 de remoção de coliformes totais e 2-4 log10 de remoção de Escherichia coli.This work presented the results of a 19-month study on the performance of constructed wetlands in terms of organic matter, solids, nutrients and coliforms removal in pilot scale unities with horizontal, subsurface and surface flow, with hydraulic retention time from 1.3 to 5.3 days, as post-treatment of UASB effluents (domestic wastewater. Organic matter and solids were effectively and consistently removed, with average values of 70, 80 and 60% for TSS, BOD5 and COD, respectively. Nutrients removal, after a promising start up, became unstable and apparently influenced by temperature. The treatment system has also shown high potential to remove coliforms, although with relatively wide variations over the study period: ≈ 2 log10 reduction of total coliforms and 2-4 log10 reduction of Escherichia coli.
ESTUDIO COMPARATIVO DE LA REMOCIÓN DE MATERIA ORG�NICA EN HUMEDALES CONSTRUIDOS DE FLUJO HORIZONTAL SUBSUPERFICIAL USANDO TRES ESPECIES DE MACRÓFITAS ESTUDO COMPARATIVO DA REMOÇÃO DE MATÉRIA ORGÂNICA EM BANHADOS CONSTRU�DOS DE FLUXO HORIZONTAL SUBSUPERFICIAL USANDO TRES ESPÉCIES DE MACRÓFITAS COMPARATIVE STUDY OF THE ORGANIC MATTER REMOVAL IN HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLANDS USING THREE SPECIES OF MACROPHYTES
JORGE IGNACIO MONTOYA
Full Text Available Los humedales construidos se presentan actualmente como una tecnología prometedora en reducir la contaminación por aguas residuales; este estudio investigó la remoción de materia orgánica con agua residual sintética, en términos de demanda química de oxígeno (DQO, demanda biológica de oxígeno (DBO5 y mediciones in situ de pH, oxígeno y temperatura cada 15 días, durante 3 meses, en seis sistemas de humedales construidos de flujo subsuperficial horizontal, a escala piloto, sembrados con tres diferentes macrófitas: Canna limbata, Heliconia psittacorum y Phragmites sp; las remociones medias de DQO fueron de 97,31 % y 95,94 % para Canna limbata; 94,49 % y 93,50 % para Heliconia psittacorum; 97,39 % y 97,13 % para Phragmites sp. En DBO5 fueron de 100 % y 99,36 % para Canna limbata; 99,09 % y 97,49 % para Heliconia psittacorum; 100 % y 99,45 % para Phragmites sp. Se concluye que existen diferencias significativas para la remoción de DQO entre las diferentes plantas (P Os banhados construídos são agora uma tecnologia promissora para reduzir a poluição por esgotos; este estudo investigou a remoção de matéria orgânica com esgoto sintético, em termos de demanda química de oxigênio (DQO, demanda biológica de oxigênio (DBO5 e medições in situ de pH, oxigênio e temperatura a cada 15 dias durante 3 meses, em seis sistemas de banhados construídos de fluxo sub-superficial horizontal, em escala piloto plantados com três diferentes macrófitas: Canna limbata, Heliconia psittacorum e Phragmites sp; as remoçães médias de DQO média foram 97,31 % e 95,94 % para Canna limbata, 94,49 % e 93,50 % para Heliconia psittacorum; 97,39 % e 97,13 % para Phragmites sp. Em DBO5 foram de 100 % e 99,36 % para Canna limbata, 99,09 % e 97,49 % para Heliconia psittacorum; 100 % e 99,45 % para Phragmites sp. Conclui-se que existem diferenças significativas para a remoção de DQO entre plantas diferentes (P Constructed wetlands appear at the
Constructed wetlands for pollution control: processes, performance, design and operation
.... Types of constructed wetland, major design parameters, role of vegetation, hydraulic patterns, loadings, treatment efficiency, construction, operation and maintenance costs are discussed in depth...
HANDBOOK FOR CONSTRUCTED WETLANDS RECEIVING ACID MINE DRAINAGE
In the summer of 1987, a pilot constructed wetland was built at the Big Five Tunnel in Idaho Springs, Colorado. This report details the theory, design and construction of wetlands receiving acid mine drainages, based on the second and third year of operation of this wetland, whic...
Environmental footprint of constructed wetlands treating wastewater.
Gkika, Dimitra; Gikas, Georgios D; Tsihrintzis, Vassilios A
The aim of the study is to determine environmentally friendlier construction materials for constructed wetland facilities treating wastewater. This is done by computing the environmental footprint of the facility based on the methodology of life cycle assessment (LCA). This methodology reveals the dominant aggravating processes during the construction of a constructed wetland (CW) and can help to create alternative environmentally friendlier solutions. This methodology was applied for the determination of the overall environmental profile of a hybrid CW facility. The LCA was applied first to the facility as originally designed, where reinforced concrete was used in some components. Then, alternative construction materials to reinforced concrete were used, such as earth covered with high density polyethylene (HDPE) or clay, and LCA was applied again. Earth structures were found to have reduced environmental impact compared to concrete ones, and clay was found environmentally friendlier compared to HDPE. Furthermore, estimation of the construction costs of the three scenarios indicate that the last scenario is also the least expensive.
Pilot-scale comparison of constructed wetlands operated under high hydraulicloading rates and attached biofilm reactors for domestic wastewater treatment
Fountoulakis, M.S.; Terzakis, S.; Chatzinotas, A.
Four different pilot-scale treatment units were constructed to compare the feasibility of treating domestic wastewater in the City of Heraklio, Crete, Greece: (a) a freewater surface (FWS) wetland system, (b) a horizontal subsurface flow (HSF) wetland system, (c) a rotating biological contactor...
Treatment Wetlands
Dotro, Gabriela; Langergraber, Günter; Molle, Pascal; Nivala, Jaime; Puigagut, Jaume; Stein, Otto; Von Sperling, Marcos
Overview of Treatment Wetlands; Fundamentals of Treatment Wetlands; Horizontal Flow Wetlands; Vertical Flow Wetlands; French Vertical Flow Wetlands; Intensified and Modified Wetlands; Free Water Surface Wetlands; Other Applications; Additional Aspects.
Construction and operation costs of constructed wetlands treating wastewater.
Design data from nine constructed wetlands (CW) facilities of various capacities (population equivalent (PE)) are used to estimate construction and operation costs, and then to derive empirical equations relating the required facility land area and the construction cost to PE. In addition, comparisons between the costs of CW facilities based on various alternative construction materials, i.e., reinforced concrete and earth structures (covered with either high density polyethylene or clay), are presented in relation to the required area. The results show that earth structures are economically advantageous. The derived equations can be used for providing a preliminary cost estimate of CW facilities for domestic wastewater treatment.
Balancing carbon sequestration and GHG emissions in a constructed wetland
Klein, de J.J.M.; Werf, van der A.K.
In many countries wetlands are constructed or restored for removing nutrients from surface water. At the same time vegetated wetlands can act as carbon sinks when CO2 is sequestered in biomass. However, it is well known that wetlands also produce substantial amounts of greenhouse gasses CH4 and N2O.
Integrated Cr(VI) removal using constructed wetlands and composting.
Sultana, Mar-Yam; Chowdhury, Abu Khayer Md Muktadirul Bari; Michailides, Michail K; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Vayenas, Dimitrios V
The present work was conducted to study integrated chromium removal from aqueous solutions in horizontal subsurface (HSF) constructed wetlands. Two pilot-scale HSF constructed wetlands (CWs) units were built and operated. One unit was planted with common reeds (Phragmites australis) and one was kept unplanted. Influent concentrations of Cr(VI) ranged from 0.5 to 10mg/L. The effect of temperature and hydraulic residence time (8-0.5 days) on Cr(VI) removal were studied. Temperature was proved to affect Cr(VI) removal in both units. In the planted unit maximum Cr(VI) removal efficiencies of 100% were recorded at HRT's of 1 day with Cr(VI) concentrations of 5, 2.5 and 1mg/L, while a significantly lower removal rate was recorded in the unplanted unit. Harvested reed biomass from the CWs was co-composted with olive mill wastes. The final product had excellent physicochemical characteristics (C/N: 14.1-14.7, germination index (GI): 145-157%, Cr: 8-10mg/kg dry mass), fulfills EU requirements and can be used as a fertilizer in organic farming. Copyright © 2014 Elsevier B.V. All rights reserved.
Wastewater treatment in tsunami affected areas of Thailand by constructed wetlands
Brix, Hans; Koottatep, H.; Laugesen, C.H.
the systems which have been built at three locations: (a) Baan Pru Teau: A newly-built township for tsunami victims which was constructed with the contribution of the Thai Red Cross. Conventional septic tanks were installed for the treatment of blackwater from each household and its effluent and grey water...... system and a system for reuse of treated wastewater. The constructed wetland system (capacity 400Â m3/day) consists of vertical flow, horizontal subsurface flow, free water surface flow and pond units. Because the treatment plant is surrounded by resorts, restaurants and shops, the constructed wetland...... systems are designed with terrains as scenic landscaping. (c) Patong: A 5,000Â m2 constructed wetland system has been established to treat polluted water from drainage canals which collect overflow from septic tanks and grey water from residential areas. It is envisaged that these three systems will serve...
Effectiveness of pollutants removal in hybrid constructed wetlands – different configurations case study
Gajewska Magdalena
Full Text Available In recent years, an increase in interest in hybrid constructed wetland systems (HCWs has been observed. The aim of the paper is to compare different HCW configurations in terms of mass removal rates and efficiency of pollutants removal. Analysed data have been collected at multistage constructed wetlands in Poland, which are composed by at least two beds: horizontal subsurface flow (SSHF and vertical subsurface flow (SSVF. The evaluation was focused on hybrid constructed wetlands performance with HF+VF vs. VF+HF configuration, where influent wastewater of the same composition was treated. In analysed HCWs, the effective removal of organic matter from 75.2 to 91.6% COD was confirmed. Efficiency of total nitrogen removal varied from 47.3 to 91.7%. The most effective removal of TN (8.3 g m−2 d−1 occurred in the system with VF+VF+HF configuration.
Review of Constructed Subsurface Flow vs. Surface Flow Wetlands
HALVERSON, NANCY
The purpose of this document is to use existing documentation to review the effectiveness of subsurface flow and surface flow constructed wetlands in treating wastewater and to demonstrate the viability of treating effluent from Savannah River Site outfalls H-02 and H-04 with a subsurface flow constructed wetland to lower copper, lead and zinc concentrations to within National Pollutant Discharge Elimination System (NPDES) Permit limits. Constructed treatment wetlands are engineered systems that have been designed and constructed to use the natural functions of wetlands for wastewater treatment. Constructed wetlands have significantly lower total lifetime costs and often lower capital costs than conventional treatment systems. The two main types of constructed wetlands are surface flow and subsurface flow. In surface flow constructed wetlands, water flows above ground. Subsurface flow constructed wetlands are designed to keep the water level below the top of the rock or gravel media, thus minimizing human and ecological exposure. Subsurface flow wetlands demonstrate higher rates of contaminant removal per unit of land than surface flow (free water surface) wetlands, therefore subsurface flow wetlands can be smaller while achieving the same level of contaminant removal. Wetlands remove metals using a variety of processes including filtration of solids, sorption onto organic matter, oxidation and hydrolysis, formation of carbonates, formation of insoluble sulfides, binding to iron and manganese oxides, reduction to immobile forms by bacterial activity, and uptake by plants and bacteria. Metal removal rates in both subsurface flow and surface flow wetlands can be high, but can vary greatly depending upon the influent concentrations and the mass loading rate. Removal rates of greater than 90 per cent for copper, lead and zinc have been demonstrated in operating surface flow and subsurface flow wetlands. The constituents that exceed NPDES limits at outfalls H-02 a nd H
Bacterial carbon utilization in vertical subsurface flow constructed wetlands.
Tietz, Alexandra; Langergraber, Günter; Watzinger, Andrea; Haberl, Raimund; Kirschner, Alexander K T
Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the "black-box" constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial (14)C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.
Design-a-wetland: a tool for generating and assessing constructed wetland designs for wastewater treatment
Casaril, Carolina J.
Full text: Full text: The hydrological cycle is a key cycle affected by current and predicted climate change. Wetlands are one of the key ecosystems within the hydrological cycle and could contribute significantly in facing the challenges of climate change, such as water shortage. The impact of wetlands on greenhouse gas emissions is much debated and, conversely, the impact of climate change on wetlands also raises many questions. There have been many attempts to harness and integrate the natural capacities of wetlands into constructed systems. These systems are especially designed for multiple purposes. They can be used for wastewater treatment and reuse, and have the potential to increase sustainability by changing land and water use practices. This project generates a 'Design-A-Wetland' prototype model, designed to facilitate decision-making in the creation of constructed wetlands. Constructed wetlands are specifically tailored to their end use; water treatment fish and fowl habitat, flood buffer zones, or sequestration of greenhouse gases. This project attempts to answer the following questions: Can a single integrated decision model be created for the design and assessment of artificial wetlands, provided either entry or exit standards are known and specified?; Can the elements of a system of interfacing the model with public consultation be specified?; The project identifies model schematics and lays the groundwork for modelling suited to the wide variety of inputs required for decision making
Particles matter: Transformation of suspended particles in constructed wetlands
Mulling, B.T.M.
This thesis shows that constructed wetlands transform suspended particles in (treated) municipal wastewater through selective precipitation in ponds, biological filtering by plankton communities and physical and biological retention in reed beds. These processes effectively remove faecal indicator
The ecological value of constructed wetlands for treating urban runoff.
Pankratz, S; Young, T; Cuevas-Arellano-, H; Kumar, R; Ambrose, R F; Suffet, I H
The Sweetwater Authority's urban runoff diversion system (URDS) comprises constructed wetlands on a hillside between the town of Spring Valley and the Sweetwater Reservoir, California, USA. The URDS were designed to divert dry-weather and first-flush urban runoff flows from the Sweetwater reservoir. However, these constructed wetlands have developed into ecologically valuable habitat. This paper evaluates the following ecological questions related to the URDS: (1) the natural development of the species present and their growth pattern; (2) the biodiversity and pollutant stress on the plants and invertebrates; and (3) the question of habitat provided for endangered species. The URDS wetlands are comprised primarily of rush (Scirpus spp.) and cattails (Typha spp.). This vegetative cover ranged from 39-78% of the area of the individual wetland ponds. Current analyses of plant tissues and wetland sediment indicates the importance of sediment sorption for metals and plant uptake of nutrients. Analyses of URDS water following runoff events show the URDS wetlands do reduce the amount of nutrients and metals in the water column. Invertebrate surveys of the wetland ponds revealed lower habitat quality and environmental stress compared to unpolluted natural habitat. The value of the wetlands as wildlife habitat is constrained by low plant biodiversity and pollution stress from the runoff. Since the primary Sweetwater Authority goal is to maintain good water quality for drinking, any secondary utilization of URDS habitat by species (endangered or otherwise) is deemed an added benefit.
CONSTRUCTED WETLAND TECHNOLOGY TO PREVENT WATER RESOURCES POLLUTION
Zeki Gökalp
Full Text Available Discharge of untreated waste waters into surface waters creates significant pollution in these resources. Wastewaters are most of the time discharged into seas, rivers and other water bodies without any treatments due to high treatment costs both in Turkey and throughout the world. Constructed wetlands, also called as natural treatment systems, are used as an alternative treatment system to conventional high-cost treatment systems because of their low construction, operation and maintenance costs, energy demands, easy operation and low sludge generation. Today, constructed wetland systems are largely used to treat domestic wastewaters, agricultural wastewaters, industrial wastewater and runoff waters and ultimately to prevent water pollution and to improve water quality of receiving water bodies. In present study, currently implemented practices in design, construction, operation and maintenance of constructed wetlands were assessed and potential mistakes made in different phases these systems were pointed out and possible solutions were proposed to overcome these problems.
Biotic development comparisons of a wetland constructed to treat mine water drainage with a natural wetland system
Webster, H.J.; Hummer, J.W.; Lacki, M.J.
Using 5-yr of baseline data from a constructed wetland, the authors compared the biotic changes in this wetland to conditions in a natural wetland to determine if biotic development patterns were similar. The constructed wetland was built in 1985 to treat a coal mine discharge and was planted with broadleaf cattail (Typha latifolia) within the three-cell, 0.26 ha wetland. Species richness in permanent quadrants of the constructed wetland declined over the study period, while cattail coverage increased. Plant species composition diversified at the edges, with several species becoming established. The constructed wetland deepened and expanded slightly in area coverage during the study period. The constructed wetland supported herptofaunal communities that appeared more stable through time than those of the natural wetland and sustained a rudimentary food chain dependent upon autotrophic algal populations. Despite fundamental differences in substrate base, morphology, and water flow patterns, biotic trends for the constructed wetland coincided with succession-like patterns at the natural wetland. They suggest that further shifts in the biotic composition of the constructed wetland are likely, but the system should continue to persist if primary production meets or exceeds the microbial metabolic requirements necessary to treat mine drainage
Linking climate change to water provision: greywater treatment by constructed wetlands
Qomariyah, S.; Ramelan, AH; Setyono, P.; Sobriyah
Climate change has been felt to take place in Indonesia, causing the temperature to increase, additional drought with more moisture evaporates from rivers, lakes, and other bodies of water, and intense rainfall in a shorter rainy season. One of the major concerns is the risk of severe drought leading to water shortages. It will affect water supply and agriculture yields. As a country extremely vulnerable to the climate change, Indonesia must adapt to the serious environmental issues. This paper aims to offer an effort of water provision by recycling and reusing of greywater applying constructed wetland systems. The treated greywater is useful as water provision for non-consumptive uses. A recent experiment was conducted on a household yard using a single horizontal subsurface flow type of constructed wetland. The experiments demonstrated that the constructed wetland systems reduced effectively the pollutants of TSS, BOD, COD, and detergent to the level that are compliant with regulatory standards. The constructed wetland has been established for almost two years however the system still works properly.
Constructed wetlands for wastewater treatment in cold climate - A review.
Wang, Mo; Zhang, Dong Qing; Dong, Jian Wen; Tan, Soon Keat
Constructed wetlands (CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option worldwide. However, the application of CW for wastewater treatment in frigid climate presents special challenges. Wetland treatment of wastewater relies largely on biological processes, and reliable treatment is often a function of climate conditions. To date, the rate of adoption of wetland technology for wastewater treatment in cold regions has been slow and there are relatively few published reports on CW applications in cold climate. This paper therefore highlights the practice and applications of treatment wetlands in cold climate. A comprehensive review of the effectiveness of contaminant removal in different wetland systems including: (1) free water surface (FWS) CWs; (2) subsurface flow (SSF) CWs; and (3) hybrid wetland systems, is presented. The emphasis of this review is also placed on the influence of cold weather conditions on the removal efficacies of different contaminants. The strategies of wetland design and operation for performance intensification, such as the presence of plant, operational mode, effluent recirculation, artificial aeration and in-series design, which are crucial to achieve the sustainable treatment performance in cold climate, are also discussed. This study is conducive to further research for the understanding of CW design and treatment performance in cold climate. Copyright © 2017. Published by Elsevier B.V.
Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Optimization of wetland substrates and hydraulic loading.
Chen, Jun; Wei, Xiao-Dong; Liu, You-Sheng; Ying, Guang-Guo; Liu, Shuang-Shuang; He, Liang-Ying; Su, Hao-Chang; Hu, Li-Xin; Chen, Fan-Rong; Yang, Yong-Qiang
This study aimed to assess removal potential of antibiotics and antibiotic resistance genes (ARGs) in raw domestic wastewater by various mesocosm-scale horizontal subsurface-flow constructed wetlands (CWs) planted Cyperus alternifolius L. with different design parameters. Twelve CWs with three hydraulic loading rates (HLR 10, 20 and 30cm/day) and four substrates (oyster shell, zeolite, medical stone and ceramic) were set up in order to select the best optimized wetland. The result showed that 7 target antibiotics compounds including erythromycin-H2O, lincomycin, monensin, ofloxacin, sulfamerazine, sulfamethazine and novobiocin were detected, and all selected 18 genes (three sulfonamide resistance genes (sul1, sul2 and sul3), four tetracycline resistance genes (tetG, tetM, tetO and tetX), two macrolide resistance genes (ermB and ermC), three quinolone resistance genes (qnrB, qnrD and qnrS) and four chloramphenicol resistance genes (cmlA, fexA, fexB and floR)) and two integrase genes (int1 and int2) were positively detected in the domestic wastewaters. The aqueous removal rates of the total antibiotics ranged from17.9 to 98.5%, while those for the total ARGs varied between 50.0 and 85.8% by the mesocosm-scale CWs. After considering their aqueous removal rates in combination with their mass removals, the CW with zeolite as the substrate and HLR of 20cm/day was selected as the best choice. Combined chemical and biological analyses indicate that both microbial degradation and physical sorption processes were responsible for the fate of antibiotics and ARGs in the wetlands. The findings from this study suggest constructed wetlands could be a promising technology for the removal of emerging contaminants such as antibiotics and ARGs in domestic wastewater. Copyright © 2015 Elsevier B.V. All rights reserved.
Removal of mercury from gold mine effluents using Limnocharis flava in constructed wetlands.
Marrugo-Negrete, José; Enamorado-Montes, Germán; Durango-Hernández, José; Pinedo-Hernández, José; Díez, Sergi
Phytoremediation has received increased attention over the recent decades, as an emerging and eco-friendly approach that utilizes the natural properties of plants to remediate contaminated water, soils or sediments. The current study provides information about a pilot-scale experiment designed to evaluate the potential of the anchored aquatic plant Limnocharis flava for phytoremediation of water contaminated with mercury (Hg), in a constructed wetland (CW) with horizontal subsurface flow (HSSF). Mine effluent used in this experiment was collected from a gold mining area located at the Alacran mine in Colombia (Hg: 0.11 ± 0.03 μg mL -1 ) and spiked with HgNO 3 (1.50 ± 0.09 μg mL -1 ). Over a 30 day test period, the efficiency of the reduction in the heavy metal concentration in the wetlands, and the relative metal sorption by the L. flava, varied according to the exposure time. The continued rate of removal of Hg from the constructed wetland was 9 times higher than the control, demonstrating a better performance and nearly 90% reduction in Hg concentrations in the contaminated water in the presence of L. flava. The results in this present study show the great potential of the aquatic macrophyte L. flava for phytoremediation of Hg from gold mining effluents in constructed wetlands. Copyright © 2016 Elsevier Ltd. All rights reserved.
Tritium as tracer of flow in constructed wetlands
Wachniew, P.; Czuprynski, P.; Maloszewski, P.
Constructed wetlands technology is a cost-effective and environmentally friendly method used world-wide to treat waste waters of different origins. The soluble pollutants are transformed and removed mainly through the processes that occur at surfaces of plants, plant debris or filtering media. The efficiency of soluble pollutants removal is thus primarily related to the extent of contact between waste waters and the reactive surfaces. Residence time distributions function (RTD)is basic characteristic of wetland hydraulic properties and can be obtained by combined use of tracer technique and mathematical modelling. Tritium was used as to obtain RTD's of three parallel cells of a sub-surface flow constructed wetland overgrown with Pharagmites australis in Nowa Slupia. Tritium as a part of water molecule, is an ideal tracer of flow in the highly reactive environment of constructed wetlands. Results of the tracer test interpreted by the assumed model (Multi Flow Dispersion Model) of conservative solute transport revealed a complex structure of flow through the wetland. (author)
Treatment of Alkaline Stripped Effluent in Aerated Constructed Wetlands: Feasibility Evaluation and Performance Enhancement
Keli He
Full Text Available Ammonium stripping has gained increasing interest for nitrogen recovery in anaerobically digested effluents. However, the stripped effluents often still do not meet discharge standards, having high pH and residual pollutants. Constructed wetlands (CWs are an easy to operate ecosystem and have a long history of application in treatment of wastewaters with extreme pH, such as acid mine drainage. However, knowledge of the mechanistic details involved in the use of CWs to treat high alkaline drainage, such as stripped effluent, is insufficient. This study explored the feasibility and effectiveness of using three sub-surface horizontal flow CWs to treat high alkaline stripped effluent (pH > 10. Two intensification strategies—intermittent aeration and effluent recirculation—were evaluated to enhance nitrogen depuration performance. The results show that the treatment of alkaline stripped effluent is feasible due to the high buffering capacity of the wetlands. Effluent recirculation combined with intermittent artificial aeration improves nitrogen removal, with 71% total nitrogen (TN removal. Ammonia volatilization from the surface of the wetlands in high alkaline conditions only contributed to 3% of the total removed ammonium. The microbial abundance and activity had significant diversity for the various enhancement strategies used in the constructed wetland systems. Anammox is an important process for nitrogen removal in CWs treating alkaline stripped effluent, and possible enhancements of this process should be investigated further.
The use of constructed wetlands for the treatment of industrial wastewater
Skrzypiecbcef Katarzyna
Full Text Available Constructed wetlands are characterized by specific conditions enabling simultaneous various physical and biochemical processes. This is the result of specific environment for the growth of microorganisms and hydrophytes (aquatic and semiaquatic plants which are capable of living in aerobic, anaerobic and facultative anaerobic conditions. Their interaction contributes to the intensification of oxidation and reduction responsible for the removal and retention of pollutants. These processes are supported by sorption, sedimentation and assimilation. Thanks to these advantages, treatment wetland systems have been used in communal management for over 50 years. In recent years, thanks to its advantages, low operational costs and high removal efficiency, there is growing interest in the use of constructed wetlands for the treatment or pre-treatment of various types of industrial wastewater. The study analyzes current use of these facilities for the treatment of industrial wastewater in the world. The conditions of use and efficiency of pollutants removal from readily and slowly biodegradable wastewater, with special emphasis on specific and characteristic pollutants of particular industries were presented. The use of subsurface horizontal flow beds for the treatment of industrial wastewater, among others from crude oil processing, paper production, food industry including wineries and distillery, olive oil production and coffee processing was described. In Poland constructed wetlands are used for the treatment of sewage and sludge from milk processing in pilot scale or for dewatering of sewage sludge produced in municipal wastewater treatment plant treating domestic sewage with approximately 40% share of wastewater from dairy and fish industry. In all cases, constructed wetlands provided an appropriate level of treatment and in addition the so-called ecosystem service.
Performance evaluation of constructed wetlands: A review of arid ...
Aiming at environmental pollution control through the use of constructed wetlands systems (CWs) in arid and semi arid climatic region, a detailed review of CWs was undertaken. Given the practical application and simplicity of the technology, principles for building phytotechnology-ecohydrology environment used for ...
ANAEROBIC COMPOST CONSTRUCTED WETLANDS SYSTEM TECHNOLOGY - SITE ITER
In Fall 1994, anaerobic compost wetlands in both upflow and downflow configurations were constructed adjacent to and received drainage from the Burleigh Tunnel, which forms part of the Clear Creek/Central City Superfund site. The systems were operated over a 3 year period. The e...
ANAEROBIC COMPOST CONSTRUCTED WETLANDS SYSTEM TECHNOLOGY - SITE TECHNOLOGY CAPSULE
In fall 1994, anaerobic compost wetlands in both upflow and down flow configurations were constructed adjacent to and received drainage from the Burleigh tunnel, which forms part of the Clear Creek/Central City Superfund site. The systems were operated over a 3 year period. The ...
Evaluation of constructed wetland treatment performance for winery wastewater.
Grismer, Mark E; Carr, Melanie A; Shepherd, Heather L
Rapid expansion of wineries in rural California during the past three decades has created contamination problems related to winery wastewater treatment and disposal; however, little information is available about performance of on-site treatment systems. Here, the project objective was to determine full-scale, subsurface-flow constructed wetland retention times and treatment performance through assessment of water quality by daily sampling of total dissolved solids, pH, total suspended solids, chemical oxygen demand (COD), tannins, nitrate, ammonium, total Kjeldahl nitrogen, phosphate, sulfate, and sulfide across operating systems for winery wastewater treatment. Measurements were conducted during both the fall crush season of heavy loading and the spring following bottling and racking operations at the winery. Simple decay model coefficients for these constituents as well as COD and tannin removal efficiencies from winery wastewater in bench-scale reactors are also determined. The bench-scale study used upward-flow, inoculated attached-growth (pea-gravel substrate) reactors fed synthetic winery wastewater. Inlet and outlet tracer studies for determination of actual retention times were essential to analyses of treatment performance from an operational subsurface-flow constructed wetland that had been overloaded due to failure to install a pretreatment system for suspended solids removal. Less intensive sampling conducted at a smaller operational winery wastewater constructed wetland that had used pretreatment suspended solids removal and aeration indicated that the constructed wetlands were capable of complete organic load removal from the winery wastewater.
Study of Geochemical System in Constructed Wetland Using Multivariate Statistical Analysis
Chen, V.
People have recognized that the human activities lead to the degradation of the environment, and constructed wetland is one of the well-known technologies for water treatment. In constructed wetland, complicated processes should be considered such as redox reactions, acid-base reactions, adsorption-desorption between water and sediment and biochemical reactions associated with plant and microorganism. In this study, most of inorganic components were analyzed and principal component analysis (PCA) was followed for depicting the controlling biochemical reaction in the constructed wetland. The results could be a guide to operate the constructed wetland. The constructed wetland in this study is located in Taoyuan County, north Taiwan. It's a horizontal subsurface flow constructed wetland composed of ten cells. The water in wetland was pumped from Nankan River, which collects wastewater from Hwaya technology park, Linkou, Guishan and Nankan industrial zone. The water of inflow and outflow from each cell were collected for analyzing inorganic components with ICP-MS and IC. In general, the results show that water quality had dramatically changed in the first three cells and became stable in the following seven cells. In this study, PCA extracted two major factors (PCs), which can respectively explain 52.76%(PC1)and 28.32%(PC2)of variance of water quality data. PC1 separates samples of the first three cells from those of the other following cells. It is believed that there was another pollution source involved in the 4th cell because PC1 is characterized by high loadings of most of trace heavy metals. On the other hand, the hydrochemistry of water mainly evolve along PC2 axis. PC2 is composed of Fe, Mn, NH4, dissolved oxygen, pH, etc with high loadings. These chemical components are predominately controlled by redox reactions. Moreover, the deep water from the 4th cell contains high concentrations of many heavy metals, especially Cu and Ga. This confirms the
Removal of antibiotics from urban wastewater by constructed wetland optimization.
Hijosa-Valsero, María; Fink, Guido; Schlüsener, Michael P; Sidrach-Cardona, Ricardo; Martín-Villacorta, Javier; Ternes, Thomas; Bécares, Eloy
Seven mesocosm-scale constructed wetlands (CWs), differing in their design characteristics, were set up in the open air to assess their efficiency to remove antibiotics from urban raw wastewater. A conventional wastewater treatment plant (WWTP) was simultaneously monitored. The experiment took place in autumn. An analytical methodology including HPLC-MS/MS was developed to measure antibiotic concentrations in the soluble water fraction, in the suspended solids fraction and in the WWTP sludge. Considering the soluble water fraction, the only easily eliminated antibiotics in the WWTP were doxycycline (61±38%) and sulfamethoxazole (60±26%). All the studied types of CWs were efficient for the removal of sulfamethoxazole (59±30-87±41%), as found in the WWTP, and, in addition, they removed trimethoprim (65±21-96±29%). The elimination of other antibiotics in CWs was limited by the specific system-configuration: amoxicillin (45±15%) was only eliminated by a free-water (FW) subsurface flow (SSF) CW planted with Typha angustifolia; doxycycline was removed in FW systems planted with T. angustifolia (65±34-75±40%), in a Phragmites australis-floating macrophytes system (62±31%) and in conventional horizontal SSF-systems (71±39%); clarithromycin was partially eliminated by an unplanted FW-SSF system (50±18%); erythromycin could only be removed by a P. australis-horizontal SSF system (64±30%); and ampicillin was eliminated by a T. angustifolia-floating macrophytes system (29±4%). Lincomycin was not removed by any of the systems (WWTP or CWs). The presence or absence of plants, the vegetal species (T. angustifolia or P. australis), the flow type and the CW design characteristics regulated the specific removal mechanisms. Therefore, CWs are not an overall solution to remove antibiotics from urban wastewater during cold seasons. However, more studies are needed to assess their ability in warmer periods and to determine the behaviour of full-scale systems. Copyright Â
Zeki Gökalp; Sedat Karaman; Ismail Taş; Halil Kirnak
Discharge of untreated waste waters into surface waters creates significant pollution in these resources. Wastewaters are most of the time discharged into seas, rivers and other water bodies without any treatments due to high treatment costs both in Turkey and throughout the world. Constructed wetlands, also called as natural treatment systems, are used as an alternative treatment system to conventional high-cost treatment systems because of their low construction, operation and maintenance c...
Effect of Substrate, Feeding Mode and Number of Stages on the Performance of Hybrid Constructed Wetland Systems
José Alberto Herrera-Melián
Full Text Available A hybrid constructed wetland mesocosm has been used for the treatment of raw urban wastewater. The first stage was a mulch-based, subsurface, horizontal flow constructed wetland (HF. The HF achieved good removals of COD (61%; 54 g/m2·day and Total Suspended Solids (84%; 29 g/m2·day. The second stage was composed of vertical flow constructed wetlands (VF that were employed to study the effect of substrate (gravel vs. mulch, feeding mode (continuous vs. intermittent and the number of stages (1 vs. 2 on performance. High hydraulic and organic surface loadings (513–583 L/m2·day and 103–118 g/m2·day of COD were applied to the reactors. The mulch was more efficient than gravel for all the parameters analyzed. The continuous feeding allowed a 3 to 6-fold reduction of the surface area required.
Phytotoxicity testing of winery wastewater for constructed wetland treatment.
Arienzo, Michele; Christen, Evan W; Quayle, Wendy C
Rapid and inexpensive phytotoxicity bioassays for winery wastewater (WW) are important when designing winery wastewater treatment systems involving constructed wetlands. Three macrophyte wetland species (Phragmites australis, Schoenoplectus validus and Juncus ingens) were tested using a pot experiment simulating a wetland microcosm. The winery wastewater concentration was varied (0.5%, 5%, 10%, 25%, 50%, 75% and 100%) and pH was corrected for some concentrations using lime as an amendment. The tolerance of the three aquatic macrophytes species to winery wastewater was studied through biomass production, total chlorophyll and nitrogen, phosphorous and potassium tissue concentrations. The results showed that at greater than 25% wastewater concentration all the macrophytes died and that Phragmites was the least hardy species. At less than 25% wastewater concentration the wetland microcosms were effective in reducing chemical oxygen demand, phenols and total soluble solids. We also evaluated the performance of two laboratory phytotoxicity assays; (1) Garden Cress (Lepidium sativum), and (2) Onion (Allium coepa). The results of these tests revealed that the effluent was highly toxic with effective concentration, EC(50), inhibition values, as low as 0.25%. Liming the WW increased the EC(50) by 10 fold. Comparing the cress and onion bioassays with the wetland microcosm results indicated that the thresholds for toxicity were of the same order of magnitude. As such we suggest that the onion and cress bioassays could be effectively used in the wine industry for rapid wastewater toxicity assessment.
Hydraulic reliability of a horizontal wetland for wastewater treatment in Sicily.
Marzo, A; Ventura, D; Cirelli, G L; Aiello, R; Vanella, D; Rapisarda, R; Barbagallo, S; Consoli, S
The purpose of this study was to evaluate how the hydraulic behavior of a horizontal subsurface wetland (HF), that is part of the hybrid wetland (hybrid-TW) of the IKEA® store in Eastern Sicily (Italy), influences the overall wastewater treatment performance. The HF unit experiences frequent overloading peaks due to the extreme variability in the number of visitors at the store, and after 2 years of operation it showed signals of partial clogging at the inlet area. The hydraulics of the HF unit has been monitored through measurements of hydraulic conductivity at saturation (Ks), tracer tests, and geophysical (i.e. electrical resistivity tomography-ERT) measurements carried out during the years 2016 and 2017. Results indicated a general good agreement between the performed measurement techniques, thus their combination, if adequately performed and calibrated, might be a reliable tool for detecting those wetland areas mainly affected by clogging conditions. The results also indicated that partial clogging had no significant effect on the quality of the discharged water. Copyright © 2018 Elsevier B.V. All rights reserved.
Performance and bacterial community structure of a 10-years old constructed mangrove wetland.
Tian, Tingting; Tam, Nora F Y; Zan, Qijie; Cheung, S G; Shin, Paul K S; Wong, Y S; Zhang, Li; Chen, Zhanghe
Constructed mangrove wetland has been used for wastewater treatment but its long-term performance has not been reported. One-year monitoring of a 10-years old horizontal subsurface-flow constructed mangrove wetland consisting of three belts, two with mangrove plants and one without, revealed that the system maintained high and stable removal percentages of organic matter and nutrients, and planted belts performed better than unplanted control. Substrates in belts planted with Aegiceras corniculatum or Kandelia obovata had higher abundance of ammonifiers, nitrifiers and denitrifiers but lower total heterotrophic bacteria than unplanted substrate. Denaturing gradient gel electrophoresis showed that microbial diversity in planted substrate was significantly lower than that in unplanted one. The bacteria in substrates, irrespective to belts, were phylogenetically related to Proteobacteria (most dominant), Acidobacteria, Firmicutes, Nitrospirae, Gemmatimonadetes, Chloroflexi and Cyanobacteria. The steady performance of this 10-year old constructed mangrove wetland was affected by the abundance and diversity of bacterial community in substrate. Copyright © 2017 Elsevier Ltd. All rights reserved.
Hydraulic and hydrological aspects of an evapotranspiration-constructed wetland combined system for household greywater treatment.
Filho, Fernando Jorge C Magalhães; Sobrinho, Teodorico Alves; Steffen, Jorge L; Arias, Carlos A; Paulo, Paula L
Constructed wetlands systems demand preliminary and primary treatment to remove solids present in greywater (GW) to avoid or reduce clogging processes. The current paper aims to assess hydraulic and hydrological behavior in an improved constructed wetland system, which has a built-in anaerobic digestion chamber (AnC), GW is distributed to the evapotranspiration and treatment tank (CEvaT), combined with a subsurface horizontal flow constructed wetland (SSHF-CW). The results show that both the plants present in the units and the AnC improve hydraulic and volumetric efficiency, decrease short-circuiting and improve mixing conditions in the system. Moreover, the hydraulic conductivity measured on-site indicates that the presence of plants in the system and the flow distribution pattern provided by the AnC might reduce clogging in the SSHF-CW. It is observed that rainfall enables salt elimination, thus increasing evapotranspiration (ET), which promotes effluent reduction and enables the system to have zero discharge when reuse is unfeasible.
Performance evaluation of duplex constructed wetlands for the treatment of diesel contaminated wastewater.
Mustapha, Hassana Ibrahim; Gupta, Pankaj Kumar; Yadav, Brijesh Kumar; van Bruggen, J J A; Lens, P N L
A duplex constructed wetland (duplex-CW) is a hybrid system that combines a vertical flow (VF) CW as a first stage with a horizontal flow filter (HFF) as a second stage for a more efficient wastewater treatment as compared to traditional constructed wetlands. This study evaluated the potential of the hybrid CW system to treat influent wastewater containing diesel range organic compounds varying from C 7 - C 40 using a series of 12-week practical and numerical experiments under controlled conditions in a greenhouse (pH was kept at 7.0 ± 0.2, temperature between 20 and 23° C and light intensity between 85 and 100-μmol photons m -2 sec -1 for 16 h d -1 ). The VF CWs were planted with Phragmites australis and were spiked with different concentrations of NH 4 + -N (10, 30 and 60 mg/L) and PO 4 3- -P (3, 6 and 12 mg/L) to analyse their effects on the degradation of the supplied petroleum hydrocarbons. The removal rate of the diesel range organics considering the different NH 4 + -N and PO 4 3- -P concentrations were simulated using Monod degradation kinetics. The simulated results compared well with the observed database. The results showed that the model can effectively be used to predict biochemical transformation and degradation of diesel range organic compounds along with nutrient amendment in duplex constructed wetlands. Copyright © 2018 Elsevier Ltd. All rights reserved.
Dec 22, 2008 ... Results indicated that 39% of the total initially added amount of ametryn ... characteristics (Table 1), may result in the detection of poten- ... Water solubility at 20oC (g∙m-3) 204 ... culture, part of the resident liquid in CWs was lost, therefore ..... LIN T, WEN y, JIANG L, LI J, yANG S and ZHOu Q (2008) Study.
Constructed wetlands for treatment of dissolved phase hydrocarbons
Moore, B J; Ross, S D [Komex International, Calgary, AB (Canada); Gibson, D [Calgary Univ., AB (Canada); Hardisty, P E [Komex Clarke Bond, Bristol (United Kingdom)
The use of constructed wetlands as an alternative to conventional treatment of condensate-contaminated groundwater was studied. In 1997 a pilot scale wetland was constructed and implemented at the Gulf Strachan Gas Processing Plant to determine its ability in treating extracted groundwater contaminated with natural gas condensates. This paper presented the results of hydrocarbon removal efficiency, hydrocarbon removal mechanisms, winter operation, and the effect of hydrocarbons on vegetation health. The inflow water to the wetland contains 15 to 20 mg/L of C[sub 5]-C[sub 10] hydrocarbons, including 50 per cent BTEX compounds. During the summer months, hydrocarbon removal efficiency was 100 per cent, but decreased to 60 and 30 per cent in the spring and late fall, respectively. The hydrocarbons not removed in the wetland were eventually removed along the outflow channel. Temperature was determined to be an important factor in the variable removal rates, particularly when there is no aeration. The main hydrocarbon removal mechanisms appear to be volatilization, biodegradation and dilution. At present, plant uptake is not a factor. 12 refs., 1 tab., 3 figs.
Moore, B.J.; Ross, S.D.; Gibson, D.; Hardisty, P.E.
The use of constructed wetlands as an alternative to conventional treatment of condensate-contaminated groundwater was studied. In 1997 a pilot scale wetland was constructed and implemented at the Gulf Strachan Gas Processing Plant to determine its ability in treating extracted groundwater contaminated with natural gas condensates. This paper presented the results of hydrocarbon removal efficiency, hydrocarbon removal mechanisms, winter operation, and the effect of hydrocarbons on vegetation health. The inflow water to the wetland contains 15 to 20 mg/L of C 5 -C 10 hydrocarbons, including 50 per cent BTEX compounds. During the summer months, hydrocarbon removal efficiency was 100 per cent, but decreased to 60 and 30 per cent in the spring and late fall, respectively. The hydrocarbons not removed in the wetland were eventually removed along the outflow channel. Temperature was determined to be an important factor in the variable removal rates, particularly when there is no aeration. The main hydrocarbon removal mechanisms appear to be volatilization, biodegradation and dilution. At present, plant uptake is not a factor. 12 refs., 1 tab., 3 figs
Application of a constructed wetland system for polluted stream remediation
Tu, Y. T.; Chiang, P. C.; Yang, J.; Chen, S. H.; Kao, C. M.
In 2010, the multi-function Kaoping River Rail Bridge Constructed Wetland (KRRBW) was constructed to improve the stream water quality and rehabilitate the ecosystem of the surrounding environment of Dashu Region, Kaohsiung, Taiwan. The KRRBW consists of five wetland basins with a total water surface area of 15 ha, a total hydraulic retention time (HRT) of 10.1 days at a averaged flow rate of 14 740 m3/day, and an averaged water depth of 1.1 m. The influent of KRRBW coming from the local drainage systems containing untreated domestic, agricultural, and industrial wastewaters. Based on the quarterly investigation results of water samples taken in 2011-2012, the overall removal efficiencies were 91% for biochemical oxygen demand (BOD), 75% for total nitrogen (TN), 96% for total phosphorus (TP), and 99% for total coliforms (TC). The calculated first-order decay rates for BOD, TN, TP, NH3-N, and TC ranged from 0.14 (TN) to 0.42 (TC) 1/day. This indicates that the KRRBW was able to remove organics, TC, and nutrients effectively. The high ammonia/nitrate removal efficiency indicates that nitrification and denitrification processes occurred simultaneously in the wetland system, and the detected nitrite concentration confirmed the occurrence of denitrification/nitrification. Results from sediment analyses reveal that the sediment contained high concentrations of organics (sediment oxygen demand = 1.9-5.2 g O2/m2 day), nutrients (up to 15.8 g total nitrogen/kg of sediment and 1.48 g total phosphorus/kg of sediment), and metals (up to 547 mg/kg of Zn and 97 mg/kg of Cu). Appropriate wetland management strategies need to be developed to prevent the release of contaminants into the wetland system. The wetland system caused the variations in the microbial diversities and dominant microbial bacteria. Results show the dominant nitrogen utilization bacteria including Denitratisoma oestradiolicum, Nitrosospira sp., Nitrosovibrio sp., D. oestradiolicum, Alcaligenes sp
Plants in constructed wetlands help to treat agricultural processing wastewater
Mark Grismer
Full Text Available Over the past three decades, wineries in the western United States and sugarcane processing for ethanol in Central and South America have experienced problems related to the treatment and disposal of process wastewater. Both winery and sugarcane (molasses wastewaters are characterized by large organic loadings that change seasonally and are detrimental to aquatic life. We examined the role of plants for treating these wastewaters in constructed wetlands. In the greenhouse, subsurface-flow flumes with volcanic rock substrates and plants steadily removed approximately 80% of organic-loading oxygen demand from sugarcane process wastewater after about 3 weeks of plant growth; unplanted flumes removed about 30% less. In field studies at two operational wineries, we evaluated the performance of similar-sized, paired, subsurface constructed wetlands with and without plants; while both removed most of the oxygen demand, removal rates in the planted system were slightly greater and significantly different from those of the unplanted system under field conditions.
Technical and Regulatory Guidance Document for Constructed Treatment Wetlands
horizon in which organic material is being added. This horizon often has the characteristics of cultivation and other disturbances. Under the A horizon is...intermediate between III and II (commonly called "green rust�) induces the reduction of Se. In the case of Se accumulation, ecotoxicological effects should be...consulted before a constructed wetland system design can be approved, specifically because many restrict the use and cultivation of plant species that
The removal efficiency of constructed wetlands filled with the zeolite-slag hybrid substrate for the rural landfill leachate treatment.
He, Hailing; Duan, Zhiwei; Wang, Zhenqing; Yue, Bo
The removal efficiencies of two horizontal subsurface flow constructed wetlands (HSSF CWs, down-flow (F1) and up-flow (F2)) filled with the zeolite-slag hybrid substrate for the rural landfill leachate treatment were investigated. The adsorption experiment was conducted to evaluate the potential of zeolite and slag as the wetland substrate. The effects of distance variations along the longitudinal profile of wetland bed on pollutant removal were assessed by sampling at four locations (inlet, outlet, 0.55Â m, and 1.10Â m from the inlet). During the operation time, the influent and effluent concentrations of chemical oxygen demand (COD), ammonia nitrogen (NH 3 -N), total nitrogen (TN), heavy metals, and polycyclic aromatic hydrocarbon (PAH) were measured. The results showed that the constructed wetlands were capable of removing COD, 20.5-48.2% (F1) and 18.6-61.2% (F2); NH 3 -N, 84.0-99.9% (F1) and 93.5-99.2% (F2); TN, 80.3-92.1% (F1) and 80.3-91.2% (F2); and heavy metals, about 90% (F1 and F2). The zeolite-slag hybrid substrate performed excellent removal efficiency for the nitrogen and heavy metals. The inlet area was the most active region of leachate removal. The up-flow constructed wetland (F2) has a higher removal efficiency for the PAH compounds. The significant removal efficiency illustrated that the rural landfill leachate can be treated using the horizontal subsurface flow constructed wetland filled with the zeolite-slag hybrid substrate.
Treatment of Olive Mill Wastewater with Constructed Wetlands
Full Text Available The objective of this study was to investigate the application of constructed wetlands as a mean to manage olive mill wastewater (OMW. Two free water surface (FWS constructed wetlands, one without (CW1 and one with effluent recirculation (CW2, were operated for a two-year period with diluted OMW (1:10 and evaluated in terms of the removal of COD, TSS, TKN, NH4+-N, NO3−-N, TP and total phenols. The organic loading rate of CWs was adjusted to 925 kg BOD/ha·d. In CW1 the removal efficiency averaged 80%, 83%, 78%, 80%, and 74% for COD, TSS, TKN, TP, and total phenols, respectively, during the operation period. Effluent recirculation further improved the treatment efficiency which approached 90%, 98%, 87%, 85%, and 87% for COD, TSS, TKN, TP, and total phenols, respectively. Constructed wetlands also showed high removal efficiency for NH4+-N. Nitrate concentration maintained low in both CWs basins, probably due to the prevalence of high denitrification rates that efficiently removed the NO3--N produced by NH4+-N oxidation. Despite the increased removal percentages, pollutant concentration in effluent exceeded the allowable limits for discharge in water bodies, suggesting that additional practices, including enhanced pre-application treatment and/or higher dilution rates, are required to make this practice effective for OMW management.
Biological Cr(VI) removal using bio-filters and constructed wetlands.
Michailides, Michail K; Sultana, Mar-Yam; Tekerlekopoulou, Athanasia G; Akratos, Christos S; Vayenas, Dimitrios V
The bioreduction of hexavalent chromium from aqueous solution was carried out using suspended growth and packed-bed reactors under a draw-fill operating mode, and horizontal subsurface constructed wetlands. Reactors were inoculated with industrial sludge from the Hellenic Aerospace Industry using sugar as substrate. In the suspended growth reactors, the maximum Cr(VI) reduction rate (about 2 mg/L h) was achieved for an initial concentration of 12.85 mg/L, while in the attached growth reactors, a similar reduction rate was achieved even with high initial concentrations (109 mg/L), thus confirming the advantage of these systems. Two horizontal subsurface constructed wetlands (CWs) pilot-scale units were also built and operated. The units contained fine gravel. One unit was planted with common reeds and one was kept unplanted. The mean influent concentrations of Cr(VI) were 5.61 and 5.47 mg/L for the planted and unplanted units, respectively. The performance of the planted CW units was very effective as mean Cr(VI) removal efficiency was 85% and efficiency maximum reached 100%. On the contrary, the unplanted CW achieved very low Cr(VI) removal with a mean value of 26%. Both attached growth reactors and CWs proved efficient and viable means for Cr(VI) reduction.
Iron oxides stimulate microbial monochlorobenzene in situ transformation in constructed wetlands and laboratory systems
Schmidt, Marie; Wolfram, Diana; Birkigt, Jan; Ahlheim, Jörg; Paschke, Heidrun; Richnow, Hans-Hermann; Nijenhuis, Ivonne
Natural wetlands are transition zones between anoxic ground and oxic surface water which may enhance the (bio)transformation potential for recalcitrant chloro-organic contaminants due to the unique geochemical conditions and gradients. Monochlorobenzene (MCB) is a frequently detected groundwater contaminant which is toxic and was thought to be persistent under anoxic conditions. Furthermore, to date, no degradation pathways for anoxic MCB removal have been proven in the field. Hence, it is important to investigate MCB biodegradation in the environment, as groundwater is an important drinking water source in many European countries. Therefore, two pilot-scale horizontal subsurface-flow constructed wetlands, planted and unplanted, were used to investigate the processes in situ contributing to the biotransformation of MCB in these gradient systems. The wetlands were fed with anoxic MCB-contaminated groundwater from a nearby aquifer in Bitterfeld, Germany. An overall MCB removal was observed in both wetlands, whereas just 10% of the original MCB inflow concentration was detected in the ponds. In particular in the gravel bed of the planted wetland, MCB removal was highest in summer season with 73 ± 9% compared to the unplanted one with 40 ± 5%. Whereas the MCB concentrations rapidly decreased in the transition zone of unplanted gravel to the pond, a significant MCB removal was already determined in the anoxic gravel bed of the planted system. The investigation of hydro-geochemical parameters revealed that iron and sulphate reduction were relevant redox processes in both wetlands. In parallel, the addition of ferric iron or nitrate stimulated the mineralisation of MCB in laboratory microcosms with anoxic groundwater from the same source, indicating that the potential for anaerobic microbial degradation of MCB is present at the field site. - Highlights: • MCB removal in anoxic gravel bed of a planted and an unplanted constructed wetland was accompanied by iron
Schmidt, Marie; Wolfram, Diana; Birkigt, Jan [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research — UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Ahlheim, Jörg [Department of Groundwater Remediation, Helmholtz Centre for Environmental Research — UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Paschke, Heidrun [Department of Analytical Chemistry, Helmholtz Centre for Environmental Research — UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Richnow, Hans-Hermann [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research — UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Nijenhuis, Ivonne, E-mail: ivonne.nijenhuis@ufz.de [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research — UFZ, Permoserstrasse 15, 04318 Leipzig (Germany)
Integrated Constructed Wetlands (ICW) for livestock wastewater management.
Harrington, Rory; McInnes, Robert
Social, economic and environmental coherence is sought in the management of livestock wastewater. Wetlands facilitate the biogeochemical processes that exploit livestock wastewater and provide opportunities to achieve such coherence and also to deliver on a range of ecosystem services. The Integrated Constructed Wetland (ICW) concept integrates three inextricably linked objectives: water quantity and quality management, landscape-fit to improve aesthetic site values and enhanced biodiversity. The synergies derived from this explicit integration allow one of the key challenges for livestock management to be addressed. An example utilizing twelve ICW systems from a catchment on the south coast of Ireland demonstrates that over an eight year period mean reduction of total and soluble phosphorus (molybdate reactive phosphorus) exceeded 95% and the mean removal of ammonium-N exceeded 98%. This paper reviews evidence regarding the capacity of ICWs to provide a coherent and sustainable alternative to conventional systems.
An introduction to constructed wetlands (reed beds) sustainable low cost wastewater treatment plants
Ahmad, M.I.
because it is essentially simple, cheap and sustainable. Because they achieve a natural balance, well designed reed bed systems will more or less look after themselves. They do not need much power, they do not need any chemicals, they need very little maintenance, and the water leaving such a system can be very clean - certainly clean enough to pass the National Water Quality Standards. A well designed reed bed system needs both aquatic plants and special water movement. The main plants used is still the Common reed (Pragmatism karaka - Nari), Cattail (Typha australis - Dab) and Vetiver grass (Khus). Almost all these aquatic plants are available in natural wetlands, along rivers, canals, water courses, and water logged areas in Pakistan. The constructed wetlands (Reed Beds) utilize horizontal flow system, vertical flow system or combination of both. The horizontal system includes 'free water surface (FWS)' wetlands and 'vegetated submerged bed (VSB)' wetlands. The vertical system invariably uses VSB system. The required land area depends on the wastewater flow. However, in the rural setting, the horizontal system requires about 1.0 square meter / person (or population equivalent in case of an industry) and the vertical system even less than that. A working reed bed system can be designed as a public area like a park with water cascades, bridges, shallow pools with fish, and small islands for birds. There is no smell. no flies. no noise, no chemicals. and no machines. The only regular maintenance work is harvesting the reeds once a year and occasional weeding (without poisons) There is potential for the combination of reed beds with a methane process in which the bulk of sludge is removed by settlement and fed to a methane digester to produce energy, and the supernatant is then cleaned with reed beds. This may becomes a practical solution for systems in urban areas. In flat areas like large towns can be split up into segments, each served by a separate reed bed system
The use of hybrid constructed wetlands for wastewater treatment with special attention to nitrogen removal: a review of a recent development.
The hybrid systems were developed in the 1960s but their use increased only during the late 1990 s and in the 2000s mostly because of more stringent discharge limits for nitrogen and also more complex wastewaters treated in constructed wetlands (CWs). The early hybrid CWs consisted of several stages of vertical flow (VF) followed by several stages of horizontal flow (HF) beds. During the 1990 s, HF-VF and VF-HF hybrid systems were introduced. However, to achieve higher removal of total nitrogen or to treat more complex industrial and agricultural wastewaters other types of hybrid constructed wetlands including free water surface (FWS) CWs and multistage CWs have recently been used as well. The survey of 60 hybrid constructed wetlands from 24 countries reported after 2003 revealed that hybrid constructed wetlands are primarily used on Europe and in Asia while in other continents their use is limited. The most commonly used hybrid system is a VF-HF constructed wetland which has been used for treatment of both sewage and industrial wastewaters. On the other hand, the use of a HF-VF system has been reported only for treatment of municipal sewage. Out of 60 surveyed hybrid systems, 38 have been designed to treat municipal sewage while 22 hybrid systems were designed to treat various industrial and agricultural wastewaters. The more detailed analysis revealed that VF-HF hybrid constructed wetlands are slightly more efficient in ammonia removal than hybrid systems with FWS CWs, HF-VF systems or multistage VF and HF hybrid CWs. All types of hybrid CWs are comparable with single VF CWs in terms of NH4-N removal rates. On the other hand, CWs with FWS units remove substantially more total nitrogen as compared to other types of hybrid constructed wetlands. However, all types of hybrid constructed wetlands are more efficient in total nitrogen removal than single HF or VF constructed wetlands. Copyright © 2013 Elsevier Ltd. All rights reserved.
Dewatering and Treatment of Septage Using Vertical Flow Constructed Wetlands
Yee Yong Tan
Full Text Available The vertical flow constructed wetland (VFCW has become an attractive decentralised technology for septage treatment. One of the main purposes of the septage treatment is to reduce the volume of raw septage through dewatering, where the solids content is retained in the wetland bed and the water content is released. The retention of solids forms a layer of sludge deposit at the wetland surface, and the drained water, the so-called leachate, typically contains a lower solids content. This article reports the performance of dewatering and filtration of a pilot-scale VFCW designed for septage treatment. A comparison between two feeding strategies, hydraulic loading rate (HLR and solids loading rate (SLR, is presented. The dewatering efficiency through drainage was found to be dependent on the solids load. The removal of total solids (TS and chemical oxygen demand (COD were excellent as the quality of leachate showed that more than 90% of TS and COD were retained in the system. This study reveals that the feeding based on SLR delivered a more sustainable performance for dewatering and solids removal. The build-up of sludge deposit significantly deteriorated the dewatering efficiency through drainage, but it tended to improve the filtration capacity.
Large Constructed Wetlands for Phosphorus Control: A Review
Robert H. Kadlec
Full Text Available This paper reviews aspects of the performance of large (>40 ha constructed treatment wetlands intended for phosphorus control. Thirty-seven such wetlands have been built and have good data records, with a median size of 754 ha. All are successfully removing phosphorus from a variety of waters. Period of record median concentration reductions were 71%, load reductions 0.77 gP·m−2·year−1, and rate coefficients 12.5 m·year−1. Large wetlands have a narrower performance spectrum than the larger group of all sizes. Some systems display startup trends, ranging to several years, likely resulting from antecedent soil and vegetation conditions. There are internal longitudinal gradients in concentration, which vary with lateral position and flow conditions. Accretion in inlet zones may require attention. Concentrations are reduced to plateau values, in the range of about 10–50 mgP·m−3. Vegetation type has an effect upon performance measures, and its presence facilitates performance. Trends in the performance measures over the history of individual systems display only small changes, with both increases and decreases occurring. Such trends remove little of the variance in behavior. Seasonality is typically weak for steady flow systems, and most variability appears to be stochastic. Stormwater systems display differences between wet and dry season behavior, which appear to be flow-driven. Several models of system performance have been developed, both steady and dynamic.
Efficiency of a constructed wetland for wastewaters treatment
Fernanda Travaini-Lima
Full Text Available AIM: The limnological characteristics of three different inlets water of the constructed wetland were compared in terms of concentration data and loading rate data and evaluated the removal efficiencies of nutrients, solids, BOD5, chlorophyll-a and thermotolerant coliforms (TC by the treatment system; METHODS: The constructed wetland, measuring 82.8 m² and with detention time of 1 hour and 58 minutes in the rainy season and 2 hours and 42 minutes in the dry one, was provided with four species, Cyperus giganteus Vahl, Typha domingensis Pers., Pontederia cordata L. e Eichhornia crassipes (Mart. Solms. The sampling sites evaluated in the dry (D and rainy (R seasons were: inlet water from aquaculture farm = IA; inlet channel of rainwater runoff = IR; inlet from UASB wastewater = IB; outlet wetland = OUT. The conductivity, pH, temperature, dissolved oxygen, alkalinity, BOD5, total soluble and dissolved solids, nitrogen, phosphorus, chlorophyll-a and TC were analyzed. Multivariate analyses, such as Cluster and Principal Components Analysis (PCA, were carried out to group sampling sites with similar limnological characteristics; RESULTS: In the PCA with the concentration data was retained 90.52% variability of data, correlating the inlet IB with high concentrations of conductivity, alkalinity, pH, TC, nutrients and solids. Regarding loading rate data, the PCA was retained 80.9% of the data's total variability and correlated the sampling sites IA D, IA R and OUT R with higher BOD5, chlorophyll-a, TDS, nitrate, nitrite, total-P, temperature, oxygen and water flow. The highest removal efficiencies rates occurred in the dry season, mainly in concentration, with 78% of ammonia, 95.5% of SRP, 94.9% of TSS and 99.9% of TC; CONCLUSIONS: The wetland was highly efficacious in the removal of nutrients, solids, BOD5, chlorophyll-a and TC, mainly during the dry season. The system restructuring to increase the detention time during the rainy season and a pre
Mosquito production from four constructed treatment wetlands in peninsular Florida.
Rey, Jorge R; O'Meara, George F; O'Connell, Sheila M; Cutwa-Francis, Michele M
Several techniques were used to sample adult and immature mosquitoes in 4 constructed treatment wetlands in Florida. Adults of 19 species (7 genera) of mosquitoes were collected, and immatures of the most abundant species and of 60% of all species also were collected. Few significant differences between sites and stations in the numbers of mosquitoes collected were discovered. Culex nigripalpus Theobald was the most abundant mosquito found in adult (carbon dioxide-baited suction traps) and ovitrap collections, whereas Mansonia spp. and Uranotaenia spp. were most common in pump-dip-grab samples. The roles of rooted and floating vegetation and of water quality in determining mosquito production from these areas are discussed.
Driving forces behind the construction of an eco-compensation mechanism for wetlands in China
Wang, Changhai
This research revealed important driving forces behind the construction of an eco-compensation mechanism for wetlands (DFEMW) in China. Using China's provincial panel data from 1978 to 2008, a fixed-effects model was used to analyze the impacts of agricultural production systems on wetlands. We identified three DFEMW as follows: the change of wetland resources and protection measures in China; declaration and implementation of the provincial Wetland Protection Ordinance; and wetland degradation by agricultural production systems, which necessitated the establishment of a wetland eco-compensation mechanism. In addition to the DFEMW, a significant positive correlation between wetland area and both rural population and gross agricultural production was identified, in addition to a negative correlation with chemical fertilizer usage, reservoir storage capacity, and irrigation area. The underlying reasons for the serious degradation and inadequate protection of wetlands were market failure and government failure; these were the driving forces behind the need to establish a wetland eco-compensation mechanism. From a governmental perspective, it has been difficult to rectify market failures in resource distribution and thus to prevent wetland degradation. Factors include conflicts of interest, lack of investment, effective special laws, a simple means to protect wetlands, and a multidisciplinary management system. Therefore, the key factor is the coordination of interest relationships between those who utilize wetlands and those who seek to minimize wetland degradation and effectively protect wetlands.
Bioaccumulation of metals in constructed wetlands used to treat acid drainage
Edwards, G.S.; Mays, P.A.
Constructed wetlands are being used extensively as a potential mitigation for acid drainage. However, removal of metals to meet compliance requirements has varied among wetlands, ranging from partial to total success. In addition, wetlands are sinks for contaminants found in acid drainage, and bioaccumulation of these contaminants to levels that would adversely affect the food web is of growing concern. The primary objective of this project was to determine whether bioaccumulation of metals occurs in wetlands constructed for treatment of acid drainage. Water, sediment, plant and benthos samples were collected from two wetlands constructed by the Tennessee Valley Authority and a natural wetland in the spring and fall of 1992, and metal concentrations were determined. One of the constructed wetlands, Impoundment 1, has generally been in compliance for NPDES; the other, Widow's Creek, has never been in compliance. Preliminary results indicate similarities in sediment and plant metal concentrations between Impoundment 1 and the natural wetland and greater metal concentrations in the sediment and plants at Widow's Creek. Data also indicate that Mn, Zn, Cu, Ni, and Cr are being accumulated in the plants at each wetland. However, accumulation of metals by these plants probably accounts for only a small percentage of the removal of the annual metal load supplied to each wetland. Bioaccumulation of metals in the benthic organisms at each wetland is currently being investigated
Constructed wetland using corncob charcoal substrate: pollutants removal and intensification.
Liu, Mao; Li, Boyuan; Xue, Yingwen; Wang, Hongyu; Yang, Kai
To investigate the feasibility of using corncob charcoal substrate in constructed wetlands, four laboratory-scale vertical flow constructed wetlands (VFCWs) were built. Effluent pollutant (chemical oxygen demand (COD), NH 4 + -N, total phosphorus (TP)) concentrations during the experiment were determined to reveal pollutant removal mechanisms and efficiencies at different stages. In the stable stage, a VFCW using clay ceramisite substrate under aeration attained higher COD (95.1%), and NH 4 + -N (95.1%) removal efficiencies than a VFCW using corncob charcoal substrate (91.5% COD, 91.3% NH 4 + -N) under aeration, but lower TP removal efficiency (clay ceramisite 32.0% and corncob charcoal 40.0%). The VFCW with raw corncob substrate showed stronger COD emissions (maximum concentration 3,108 mg/L) than the corncob charcoal substrate (COD was lower than influent). The VFCW using corncob charcoal substrate performed much better than the VFCW using clay ceramisite substrate under aeration when the C/N ratio was low (C/N = 1.5, TN removal efficiency 36.89%, 4.1% respectively). These results suggest that corncob charcoal is a potential substrate in VFCWs under aeration with a unique self -supplying carbon source property in the denitrification process.
Performance Evaluation of Integrated Constructed Wetland for Domestic Wastewater Treatment.
Sehar, Shama; Naz, Iffat; Khan, Sumera; Naeem, Sana; Perveen, Irum; Ali, Naeem; Ahmed, Safia
Simple, budget friendly, laboratory-scale integrated constructed wetland (ICW) was designed to assess domestic wastewater treatment performance at a loading rate of 75 mm/d, planted with native plant species: Veronica-angallis aquatica and compared with non-vegetative control system at various residence times of 4, 8, 12, 16, 20, 24, and 28 days. Results revealed that the vegetated ICW demonstrated superior performance over non-vegetated control: 69.12 vs 17.12%, 67.77 vs 16.04%, 68 vs 16.48%, 71.19 vs 6.56%, 71.54 vs 14.80%, and 72.04 vs 11.41% for total dissolved solids, total suspended solids, phosphates (PO4(-)), sulfate (SO4(-)), nitrate (NO3(-)), and nitrite (NO2(-)), respectively, at 20 days residence times. Reduction in bacterial counts (2.79 × 10(4) CFU/mL) and fecal pathogens (345.5 MPN index/100 mL) was observed in V. aquatica at 20 days residence time. Therefore, the present study highlights not only the presence of vegetation but also appropriate residence time in constructed wetlands for better performances.
Characterisation of microbial biocoenosis in vertical subsurface flow constructed wetlands
Tietz, Alexandra; Kirschner, Alexander; Langergraber, Guenter; Sleytr, Kirsten; Haberl, Raimund
In this study a quantitative description of the microbial biocoenosis in subsurface vertical flow constructed wetlands fed with municipal wastewater was carried out. Three different methods (substrate induced respiration, ATP measurement and fumigation-extraction) were applied to measure the microbial biomass at different depths of planted and unplanted systems. Additionally, bacterial biomass was determined by epifluorescence microscopy and productivity was measured via 14 C leucine incorporation into bacterial biomass. All methods showed that > 50% of microbial biomass and bacterial activity could be found in the first cm and about 95% in the first 10 cm of the filter layer. Bacterial biomass in the first 10 cm of the filter body accounted only for 16-19% of the total microbial biomass. Whether fungi or methodical uncertainties are mainly responsible for the difference between microbial and bacterial biomass remains to be examined. A comparison between the purification performance of planted and unplanted pilot-scale subsurface vertical flow constructed wetlands (PSCWs) showed no significant difference with the exception of the reduction of enterococci. The microbial biomass in all depths of the filter body was also not different in planted and unplanted systems. Compared with data from soils the microbial biomass in the PSCWs was high, although the specific surface area of the used sandy filter material available for biofilm growth was lower, especially in the beginning of the set-up of the PSCWs, due to missing clay and silt fraction
Comparison of simple, small, full-scale sewage treatment systems in Brazil: UASB-maturation ponds-coarse filter; UASB-horizontal subsurface-flow wetland; vertical-flow wetland (first stage of French system).
von Sperling, M
This paper presents a comparison between three simple sewage treatment lines involving natural processes: (a) upflow anaerobic sludge blanket (UASB) reactor-three maturation ponds in series-coarse rock filter; (b) UASB reactor-horizontal subsurface-flow constructed wetland; and (c) vertical-flow constructed wetlands treating raw sewage (first stage of the French system). The evaluation was based on several years of practical experience with three small full-scale plants receiving the same influent wastewater (population equivalents of 220, 60 and 100 inhabitants) in the city of Belo Horizonte, Brazil. The comparison included interpretation of concentrations and removal efficiencies based on monitoring data (organic matter, solids, nitrogen, phosphorus, coliforms and helminth eggs), together with an evaluation of practical aspects, such as land and volume requirements, sludge production and handling, plant management, clogging and others. Based on an integrated evaluation of all aspects involved, it is worth emphasizing that each system has its own specificities, and no generalization can be made on the best option. The overall conclusion is that the three lines are suitable for sewage treatment in small communities in warm-climate regions.
Constructed Wetland Treatment Systems For Water Quality Improvement
Nelson, E.
The Savannah River National Laboratory implemented a constructed wetland treatment system (CWTS) in 2000 to treat industrial discharge and stormwater from the Laboratory area. The industrial discharge volume is 3,030 m 3 per day with elevated toxicity and metals (copper, zinc and mercury). The CWTS was identified as the best treatment option based on performance, capital and continuing cost, and schedule. A key factor for this natural system approach was the long-term binding capacity of heavy metals (especially copper, lead, and zinc) in the organic matter and sediments. The design required that the wetland treat the average daily discharge volume and be able to handle 83,280 m 3 of stormwater runoff in a 24 hour period. The design allowed all water flow within the system to be driven entirely by gravity. The CWTS for A-01 outfall is composed of eight one-acre wetland cells connected in pairs and planted with giant bulrush to provide continuous organic matter input to the system. The retention basin was designed to hold stormwater flow and to allow controlled discharge to the wetland. The system became operational in October of 2000 and is the first wetland treatment system permitted by South Carolina DHEC for removal of metals. Because of the exceptional performance of the A-01 CWTS, the same strategy was used to improve water quality of the H-02 outfall that receives discharge and stormwater from the Tritium Area of SRS. The primary contaminants in this outfall were also copper and zinc. The design for this second system required that the wetland treat the average discharge volume of 415 m 3 per day, and be able to handle 9,690 m 3 of stormwater runoff in a 24 hour period. This allowed the building of a system much smaller than the A-01 CWTS. The system became operational in July 2007. Metal removal has been excellent since water flow through the treatment systems began, and performance improved with the maturation of the vegetation during the first season of
The Savannah River National Laboratory implemented a constructed wetland treatment system (CWTS) in 2000 to treat industrial discharge and stormwater from the Laboratory area. The industrial discharge volume is 3,030 m{sup 3} per day with elevated toxicity and metals (copper, zinc and mercury). The CWTS was identified as the best treatment option based on performance, capital and continuing cost, and schedule. A key factor for this natural system approach was the long-term binding capacity of heavy metals (especially copper, lead, and zinc) in the organic matter and sediments. The design required that the wetland treat the average daily discharge volume and be able to handle 83,280 m{sup 3} of stormwater runoff in a 24 hour period. The design allowed all water flow within the system to be driven entirely by gravity. The CWTS for A-01 outfall is composed of eight one-acre wetland cells connected in pairs and planted with giant bulrush to provide continuous organic matter input to the system. The retention basin was designed to hold stormwater flow and to allow controlled discharge to the wetland. The system became operational in October of 2000 and is the first wetland treatment system permitted by South Carolina DHEC for removal of metals. Because of the exceptional performance of the A-01 CWTS, the same strategy was used to improve water quality of the H-02 outfall that receives discharge and stormwater from the Tritium Area of SRS. The primary contaminants in this outfall were also copper and zinc. The design for this second system required that the wetland treat the average discharge volume of 415 m{sup 3} per day, and be able to handle 9,690 m{sup 3} of stormwater runoff in a 24 hour period. This allowed the building of a system much smaller than the A-01 CWTS. The system became operational in July 2007. Metal removal has been excellent since water flow through the treatment systems began, and performance improved with the maturation of the vegetation during
Treatment performances of French constructed wetlands: results from a database collected over the last 30 years.
Morvannou, A; Forquet, N; Michel, S; Troesch, S; Molle, P
Approximately 3,500 constructed wetlands (CWs) provide raw wastewater treatment in France for small communities (Built during the past 30 years, most consist of two vertical flow constructed wetlands (VFCWs) in series (stages). Many configurations exist, with systems associated with horizontal flow filters or waste stabilization ponds, vertical flow with recirculation, partially saturated systems, etc. A database analyzed 10 years earlier on the classical French system summarized the global performances data. This paper provides a similar analysis of performance data from 415 full-scale two-stage VFCWs from an improved database expanded by monitoring data available from Irstea and the French technical department. Trends presented in the first study are confirmed, exhibiting high chemical oxygen demand (COD), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN) removal rates (87%, 93% and 84%, respectively). Typical concentrations at the second-stage outlet are 74 mgCOD L(-1), 17 mgTSS L(-1) and 11 mgTKN L(-1). Pollutant removal performances are summarized in relation to the loads applied at the first treatment stage. While COD and TSS removal rates remain stable over the range of applied loads, the spreading of TKN removal rates increases as applied loads increase.
In situ construction of horizontal soil containment barrier at Fernald
Ridenour, D.; Pettit, P.J.; Walker, J.
An innovative method of placing soil barriers to contain vertical flow is being prepared for demonstration by the Fernald Environmental Restoration Management Corporation (FERMCO), working in conjunction with the Department of Energy Office of Technology Development (DOE/OTD) and two principle subcontractors. The method employs proven directional drilling techniques, jet grouting technology and unique placement tooling to form horizontal soil barriers in situ. This is done without disturbance to existing land disposed wastes. This paper is a summary report on the current state of that demonstration, including: a discussion of the construction methods, the results of the initial tool tests, an overview of the Fernald site conditions and, the resulting path of tooling development for the second phase of tool testing
Use of tracer tests to evaluate hydraulic properties of constructed wetlands
Knowledge of hydraulic properties is a perquisite for studies of constructed wetlands functioning. Bromide ions and tritium were used as a tracers to derive RTDs for two constructed wetlands: a reed bed with subsurface flow and a Lemna pond. Quantitative hydraulic characteristics (mean travel time of water, dispersion number) of the wetlands were evaluated from RTDs (Residence Time Distributions) by means of a mathematical model of waste water flow. (author)
Effectiveness of a constructed wetland for acid mine drainage reclamation
Grant, A.J.; Ramey, B.A.; Jarrett, L.; Hart, G.
Acid mine drainage (AMD) from an abandoned coal mine in southcentral Kentucky had pH levels as low as 2.5 and iron concentrations as high as 630 mg/L. In the summer of 1992, the SCS constructed a wetland system to treat the AMD that involved use of both physical and biological treatment. The AMD was fed into three anoxic limestone beds, followed by an aeration pond, before entering a series of four cattail cells and a polishing pond. Flow of AMD was initiated in the fall of 1992, and chemical and biological monitoring were conducted throughout the winter months. Chemical analysis of the water along the flow path of the AMD during the first six months of operation indicated that the limestone beds improved the pH substantially, and that most of the metals were removed prior to the water entering the cattail cells. The effectiveness of the wetland system to improve water quality also was monitored using the cladoceran (Ceriodaphnia dubia) survival and reproduction test. Determination of toxic levels indicated a substantial improvement in water quality below the limestone beds, and a slight decrease in toxicity throughout the cattail cells. However, toxic levels stayed the same or increased in the polishing pond. Water quality monitoring will continue through the growing season of 1993 to assess the impact of plant growth on the reclamation of the AMD
Kinetic and empirical design criteria for constructed wetlands
Nix, P.G.; Gulley, J.R.
A study was conducted to demonstrate the capabilities of wetlands as long-term, self-sustaining natural systems for the treatment of large quantities of waste water released from tailings ponds after mine abandonment. Constructed wetlands were built and planted with aquatic plants. The experimental design included three replicate trenches for each of two treatment systems. The objective of the research was to assess the optimum contaminant loading rates which would result in an acceptable quality of the effluent water. Using empirical data (i.e., hydrocarbon loading rates versus effluent quality), the optimal range of hydrocarbon loading was 5 to 25 gTEH/m 2/ month. Using more conservative kinetic data (i.e. microbial mineralization rates), the range of optimal treatment effectiveness was 9.6 to 13.2 gTEH/m 2/ month. The two design criteria methodologies were calculated using two independent analytical methods. The similarity in results was judged to be a confirmation of their accuracy. 20 refs., 5 figs
The microbial aspects of constructed wetlands treating simulated wastewater
Pervez, A.; Firdus, S.
The microbial populations (bacteria, actinomycetes and fungi) in six different types of 68 dm/sup 3/ experimental constructed wetlands with or with reed were quantified using standard counts of colony forming units grown on different types of medias. The wetlands were supplied with a simulated wastewater and number of environmental variables were measured, including COD, temperature, pH, Oxygen concentration, suspended solids, NH/sub 4//sup +/, NO/sub 3//sup -/ and HPO/sub 4//sup 2-/. Mean number of colony forming units of bacteria, actinomycetes and fungi differed significantly between each system, sample dates and depths. Correlation coefficient for variables were calculated to determine whether a relationship between biological and physico-chemical factors at all samples depths could be detected. Not surprisingly the numbers of bacteria and actinomycetes were strongly positively correlated with temperature and oxygen concentration. However, fungal populations were partially correlated with temperature. No correlation was found between the number of any microorganisms and the levels of HPO/sub 4//sup 2-/ in the effluent. (author)
Do constructed wetlands remove metals or increase metal bioavailability?
Xu, Xiaoyu; Mills, Gary L
The H-02 wetland was constructed to treat building process water and storm runoff water from the Tritium Processing Facility on the Department of Energy's Savannah River Site (Aiken, SC). Monthly monitoring of copper (Cu) and zinc (Zn) concentrations and water quality parameters in surface waters continued from 2014 to 2016. Metal speciation was modeled at each sampling occasion. Total Cu and Zn concentrations released to the effluent stream were below the NPDES limit, and the average removal efficiency was 65.9% for Cu and 71.1% for Zn. The metal-removal processes were found out to be seasonally regulated by sulfur cycling indicated by laboratory and model results. High temperature, adequate labile organic matter, and anaerobic conditions during the warm months (February to August) favored sulfate reduction that produced sulfide minerals to significantly remove metals. However, the dominant reaction in sulfur cycling shifted to sulfide oxidation during the cool months (September to next March). High concentrations of metal-organic complexes were observed, especially colloidal complexes of metal and fulvic acid (FA), demonstrating adsorption to organic matter became the primary process for metal removal. Meanwhile, the accumulation of metal-FA complexes in the wetland system will cause negative effects to the surrounding environment as they are biologically reactive, highly bioavailable, and can be easily taken up and transferred to ecosystems by trophic exchange. Copyright © 2018 Elsevier Ltd. All rights reserved.
Mitigation of two pyrethroid insecticides in a Mississippi Delta constructed wetland.
Moore, M T; Cooper, C M; Smith, S; Cullum, R F; Knight, S S; Locke, M A; Bennett, E R
Constructed wetlands are a suggested best management practice to help mitigate agricultural runoff before entering receiving aquatic ecosystems. A constructed wetland system (180 m x 30 m), comprising a sediment retention basin and two treatment cells, was used to determine the fate and transport of simulated runoff containing the pyrethroid insecticides lambda-cyhalothrin and cyfluthrin, as well as suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results showed 49 and 76% of the study's measured lambda-cyhalothrin and cyfluthrin masses were associated with vegetation, respectively. Based on conservative effects concentrations for invertebrates and regression analyses of maximum observed wetland aqueous concentrations, a wetland length of 215 m x 30 m width would be required to adequately mitigate 1% pesticide runoff from a 14 ha contributing area. Results of this experiment can be used to model future design specifications for constructed wetland mitigation of pyrethroid insecticides.
Removal and factors influencing removal of sulfonamides and trimethoprim from domestic sewage in constructed wetlands.
Dan A; Yang, Yang; Dai, Yu-Nv; Chen, Chun-Xing; Wang, Su-Yu; Tao, Ran
Twelve pilot-scale constructed wetlands with different configurations were set up in the field to evaluate the removal and factors that influence removal of sulfonamides (sulfadiazine, sulfapyridine, sulfacetamide, sulfamethazine and sulfamethoxazole) and trimethoprim from domestic sewage. The treatments included four flow types, three substrates, two plants and three hydraulic loading rates across two seasons (summer and winter). Most target antibiotics were efficiently removed by specific constructed wetlands; in particular, all types of constructed wetlands performed well for the degradation of sulfapyridine. Flow types were the most important influencing factor in this study, and the best removal of sulfonamides was achieved in vertical subsurface-flow constructed wetlands; however, the opposite phenomenon was found with trimethoprim. Significant relationships were observed between antibiotic degradation and higher temperature and redox potential, which indicated that microbiological pathways were the most probable degradation route for sulfonamides and trimethoprim in constructed wetlands. Copyright © 2013 Elsevier Ltd. All rights reserved.
Operational, design and microbial aspects related to power production with microbial fuel cells implemented in constructed wetlands.
Corbella, Clara; Guivernau, Miriam; Viñas, Marc; Puigagut, Jaume
This work aimed at determining the amount of energy that can be harvested by implementing microbial fuel cells (MFC) in horizontal subsurface constructed wetlands (HSSF CWs) during the treatment of real domestic wastewater. To this aim, MFC were implemented in a pilot plant based on two HSSF CW, one fed with primary settled wastewater (Settler line) and the other fed with the effluent of a hydrolytic up-flow sludge blanket reactor (HUSB line). The eubacterial and archaeal community was profiled on wetland gravel, MFC electrodes and primary treated wastewater by means of 16S rRNA gene-based 454-pyrosequencing and qPCR of 16S rRNA and mcrA genes. Maximum current (219 mA/m(2)) and power (36 mW/m(2)) densities were obtained for the HUSB line. Power production pattern correlated well with water level fluctuations within the wetlands, whereas the type of primary treatment implemented had a significant impact on the diversity and relative abundance of eubacteria communities colonizing MFC. It is worth noticing the high predominance (13-16% of relative abundance) of one OTU belonging to Geobacter on active MFC of the HUSB line that was absent for the settler line MFC. Hence, MFC show promise for power production in constructed wetlands receiving the effluent of a HUSB reactor. Copyright © 2015 Elsevier Ltd. All rights reserved.
Simplified hydraulic model of French vertical-flow constructed wetlands.
Arias, Luis; Bertrand-Krajewski, Jean-Luc; Molle, Pascal
Designing vertical-flow constructed wetlands (VFCWs) to treat both rain events and dry weather flow is a complex task due to the stochastic nature of rain events. Dynamic models can help to improve design, but they usually prove difficult to handle for designers. This study focuses on the development of a simplified hydraulic model of French VFCWs using an empirical infiltration coefficient--infiltration capacity parameter (ICP). The model was fitted using 60-second-step data collected on two experimental French VFCW systems and compared with Hydrus 1D software. The model revealed a season-by-season evolution of the ICP that could be explained by the mechanical role of reeds. This simplified model makes it possible to define time-course shifts in ponding time and outlet flows. As ponding time hinders oxygen renewal, thus impacting nitrification and organic matter degradation, ponding time limits can be used to fix a reliable design when treating both dry and rain events.
Applicability of Constructed Wetlands for Water Quality Improvement in a Tea Estate Catchment: The Pussellawa Case Study
G. M. P. R. Weerakoon
Full Text Available Water in agricultural catchments is prone to pollution from agricultural runoff containing nutrients and pesticides, and contamination from the human population working and residing therein. This study examined the quality of water in a drainage stream which runs through a congested network of 'line houses' (low-income housing, typically found arranged in straight 'lines' on estates in the tea estate catchment area of Pussellawa in central Sri Lanka. The study evaluated the applicability of vertical subsurface flow (VSSF and horizontal subsurface flow (HSSF constructed wetlands for water polishing, as the residents use the stream water for various domestic purposes with no treatment other than possibly boiling. Water flow in the stream can vary significantly over time, and so investigations were conducted at various flow conditions to identify the hydraulic loading rate (HLR bandwidth for wetland polishing applications. Two wetland models of 8 m × 1 m × 0.6 m (length × width × depth were constructed and arranged as VSSF and HSSF units. Stream water was diverted to these units at HLRs of 3.3, 4, 5, 10, 20, and 40 cm/day. Results showed that both VSSF and HSSF wetland units were capable of substantially reducing five-day biochemical oxygen demand (BOD5, total suspended solids (TSS, fecal coliform (FC, total coliform (TC, ammonia nitrogen (NH4+-N, and nitrate nitrogen (NO3−-N up to 20 cm/day HLR, with removal efficiencies of more than 64%, 60%, 90%, 93%, 70%, and 59% for BOD5, TSS, FC, TC, NH4+-N, and NO3−-N, respectively, in the VSSF wetland unit; and more than 66%, 62%, 91%, 90%, 53%, and 77% for BOD5, TSS, FC, TC, NH4+-N, and NO3−-N, respectively, in the HSSF wetland unit.
Atrazine degradation by bioaugmented sediment from constructed wetlands.
Runes, H B; Jenkins, J J; Bottomley, P J
The potential to establish pesticide biodegradation in constructed wetland sediment was investigated. Under microcosm conditions, bioaugmentation of sediment with small quantities of an atrazine spill-site soil (1:100 w/w) resulted in the mineralization of 25-30% of 14C ethyl atrazine (1-10 microg g(-1) sediment) as 14CO2 under both unsaturated and water-saturated conditions; atrazine and its common metabolites were almost undetectable after 30 days incubation. By comparison, unbioaugmented sediment supplemented with organic amendments (cellulose or cattail leaves) mineralized only 2-3% of 14C ethyl atrazine, and extractable atrazine and its common metabolites comprised approximately 70% of the original application. The population density of atrazine-degrading microorganisms in unbioaugmented sediment was increased from approximately 10(2)/g to 10(4)/g by bioaugmentation (1:100 w/w), and increased by another 60-fold (6.0x10(5) g(-1)) after incubation with 10 microg g(-1) of atrazine. A high population of atrazine degraders (approximately 10(6) g(-1)) and enhanced rates of atrazine mineralization also developed in bioaugmented sediment after incubation in flooded mesocosms planted with cattails (Typha latifolia) and supplemented with atrazine (3.2 mg l(-1), 1 microg g(-1) sediment). In the absence of atrazine, neither the population of atrazine degraders, nor the atrazine mineralizing potential of bioaugmented sediment increased, regardless of the presence or absence of cattails. Bioaugmentation might be a simple method to promote pesticide degradation in nursery run-off channeled through constructed wetlands, if persistence of degraders in the absence of pesticide is not a serious constraint.
Specifically Designed Constructed Wetlands: A Novel Treatment Approach for Scrubber Wastewater
John H. Rodgers Jr; James W. Castle; Chris Arrington: Derek Eggert; Meg Iannacone
A pilot-scale wetland treatment system was specifically designed and constructed at Clemson University to evaluate removal of mercury, selenium, and other constituents from flue gas desulfurization (FGD) wastewater. Specific objectives of this research were: (1) to measure performance of a pilot-scale constructed wetland treatment system in terms of decreases in targeted constituents (Hg, Se and As) in the FGD wastewater from inflow to outflow; (2) to determine how the observed performance is achieved (both reactions and rates); and (3) to measure performance in terms of decreased bioavailability of these elements (i.e. toxicity of sediments in constructed wetlands and toxicity of outflow waters from the treatment system). Performance of the pilot-scale constructed wetland treatment systems was assessed using two criteria: anticipated NPDES permit levels and toxicity evaluations using two sentinel toxicity-testing organisms (Ceriodaphnia dubia and Pimephales promelas). These systems performed efficiently with varied inflow simulations of FGD wastewaters removing As, Hg, and Se concentrations below NPDES permit levels and reducing the toxicity of simulated FGD wastewater after treatment with the constructed wetland treatment systems. Sequential extraction procedures indicated that these elements (As, Hg, and Se) were bound to residual phases within sediments of these systems, which should limit their bioavailability to aquatic biota. Sediments collected from constructed wetland treatment systems were tested to observe toxicity to Hyalella azteca or Chironomus tetans. Complete survival (100%) was observed for H. azteca in all cells of the constructed wetland treatment system and C. tentans had an average of 91% survival over the three treatment cells containing sediments. Survival and growth of H. azteca and C. tentans did not differ significantly between sediments from the constructed wetland treatment system and controls. Since the sediments of the constructed
Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading.
Guangwei Yu
Full Text Available For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs, two horizontal subsurface flow(HSSF CWs and two vertical subsurface flow(VSSF CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg-1 to 2.710 g·kg-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg-1 to 1.080 g·kg-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg-1 to 0.634 g·kg-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg-1 to 2.237 g·kg-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation.
Treatment of industrial effluents in constructed wetlands: challenges, operational strategies and overall performance.
Wu, Shubiao; Wallace, Scott; Brix, Hans; Kuschk, Peter; Kirui, Wesley Kipkemoi; Masi, Fabio; Dong, Renjie
The application of constructed wetlands (CWs) has significantly expanded to treatment of various industrial effluents, but knowledge in this field is still insufficiently summarized. This review is accordingly necessary to better understand this state-of-the-art technology for further design development and new ideas. Full-scale cases of CWs for treating various industrial effluents are summarized, and challenges including high organic loading, salinity, extreme pH, and low biodegradability and color are evaluated. Even horizontal flow CWs are widely used because of their passive operation, tolerance to high organic loading, and decolorization capacity, free water surface flow CWs are effective for treating oil field/refinery and milking parlor/cheese making wastewater for settlement of total suspended solids, oil, and grease. Proper pretreatment, inflow dilutions through re-circulated effluent, pH adjustment, plant selection and intensifications in the wetland bed, such as aeration and bioaugmentation, are recommended according to the specific characteristics of industrial effluents. Copyright © 2015 Elsevier Ltd. All rights reserved.
Constructed wetland: an alternative for wastewater treatment; Humedales construidos: una alternativa a considerar para el tratamiento de aguas residuales
Plaza de los Reyes del Rio, C.; Vidal Saez, G.
Research and trends dealing with sewage and industrial wastewaters treated by constructed wetlands are shown in this paper. Plant and constructed wetlands configurations are also described. Sewage domestic wastewaters from individual houses or villages have used constructed wetlands as wastewater treatment. On the other hand, constructed wetlands as finally treatment working together with conventional technologies could be a good alternative for improving the treated quality wastewater. (Author) 56 refs.
Efficiencies of freshwater and estuarine constructed wetlands for phenolic endocrine disruptor removal in Taiwan.
Hsieh, Chi-Ying; Yang, Lei; Kuo, Wen-Chien; Zen, Yi-Peng
We examined the distribution and removal efficiencies of phenolic endocrine disruptors (EDs), namely nonylphenol diethoxylates (NP2EO), nonylphenol monoethoxylates (NP1EO), nonylphenol (NP), and octylphenol (OP), in wastewater treated by estuarine and freshwater constructed wetland systems in Dapeng Bay National Scenic Area (DBNSA) and along the Dahan River in Taiwan. Water samples were taken bimonthly at 30 sites in three estuarine constructed wetlands (Datan, Pengcun and Linbian right bank (A and B)) in DBNSA, for eight sampling campaigns. The average removal efficiencies were in the range of 3.13-97.3% for wetlands in DBNSA. The highest average removal occurred in the east inlet to the outlet of the Tatan wetland. The most frequently detected compound was OP (57.7%), whose concentration was up to 1458.7 ng/L in DBNSA. NP was seen in only 20.5% of the samples. The temporal variation of EDs showed a decrease across seasons, where summer>spring>winter>autumn in these constructed wetlands. The removal efficiencies of EDs by estuarine wetlands, in decreasing order, were Datan>Pengcun>Linbian right bank in DBNSA. Water samples collected at 18 sites in three freshwater constructed wetlands (Daniaopi, Hsin-Hai I, and Hsin-Hai II) along the riparian area of Dahan River. NP2EO was the most abundant compound, with a concentration of up to 11,200 ng/L. Removal efficiencies ranged from 55% to 91% for NP1EO, NP2EO, and NP in Hsin-Hai I. The average removal potential of EDs in freshwater constructed wetlands, in decreasing order, was Hsin-Hai II>Daniaopi>Hsin-Hai I constructed wetlands. The lowest concentrations of the selected compounds were observed in the winter. The highest removal efficiency of the selected phenolic endocrine disruptors was achieved by Hsin-Hai I wetland. The calculated risk quotients used to evaluate the ecological risk were up to 30 times higher in the freshwater wetlands along Dahan River than in the estuarine (DBNSA) constructed wetlands, indicating
Establishment of a constructed wetland in extreme dryland.
Tencer, Yoram; Idan, Gil; Strom, Marjorie; Nusinow, Uri; Banet, Dorit; Cohen, Eli; Schröder, Peter; Shelef, Oren; Rachmilevitch, Shimon; Soares, Ines; Gross, Amit; Golan-Goldhirsh, Avi
The project was set to construct an extensive wetland in the southernmost region of Israel at Kibbutz Neot Smadar (30 degree 02'45" N and 35 degree 01'19" E). The results of the first period of monitoring, summary, and perspectives are presented. The constructed wetland (CW) was built and the subsequent monitoring performed in the framework of the Southern Arava Sustainable Waste Management Plan, funded by the EU LIFE Fund. The specific aims were: (1) To end current sewage disposal and pollution of the ground, the aquifer, and the dry river bed (wadi) paths by biologically treating the sewage as part of the creation of a sustainable wetland ecosystem. (2) Serve as an example of CW in the Negev highlands and the Arava Valley climates for neighboring communities and as a test ground for plants and building methods appropriate to hyper arid climate. (3) Serve as an educational resource and tourist attraction for groups to learn about water reuse, recycling, local wildlife and migrating birds, including serving the heart of a planned Ecological-Educational Bird Park. This report is intended to allow others who are planning similar systems in hyper arid climates to learn from our experience. The project is located in an extreme arid desert with less than 40 mm of rain annually and temperature ranges of -5 degree C to +42 degree C. The site receives 165-185 m3 of municipal and agricultural wastes daily, including cowshed and goat wastes and winery outflow. The CW establishment at Neot Smadar was completed in October 2006. For 8 months, clean water flowed through the system while the plants were taking root. In June 2007, the wetland was connected to the oxidation pond and full operation began. Because of seepage and evaporation, during the first several months, the water level was not high enough to allow free flow from one bed to the next. To bed A, the water was pumped periodically from the oxidation pond (Fig. 1) and from there flowed by gravitation through the rest
Vertical Subsurface Flow (VSSF) constructed wetland for domestic wastewater treatment
Perdana, M. C.; Sutanto, H. B.; Prihatmo, G.
Vertical Subsurface Flow Constructed Wetland (VSSF) is appraised to become an alternative solution for treating domestic wastewater effectively and efficiently. The system which imitates the natural wetland concept is able to reduce organic material and nutrients in wastewater; therefore, it will be more feasible to be discharged to the environment. This study aimed to compare which species is more recommended to be applied for reducing organic material and nutrients in domestic wastewater. This experimental study applied four treatments, i.e 1) control (unplanted), 2) single species Iris pseudacorus, 3) single species Echinodorus palaefolius, and 4) combination (Iris pseudacorus and Echinodorus palaefolius) with three days of retention time. The application of those plants aims for holding the role in increasing wastewater quality and adding aesthetic impression at once. The plants were planted on VSSF media, in relatively same of weight and size to compare their effectiveness in decreasing organic and inorganic load. The parameters measured pervade TDS, pH, BOD5, COD, Nitrate, and Phosphate. The plants' condition was also observed during and after the system worked. The result showed that the best average value of effectiveness for each of parameters: COD by combination treatment (50.76%), BOD5 by single I. pseudacorus (30.15%), Nitrate by single E. palaefolius (58.06%), Phosphate by single E. palaefolius (99.5%), and TDS by E.palaefolius (3.25%). The result showed that there was a significant difference of Nitrate and Phosphate reduction between control and three other treatments, while pH parameter showed non-significant change among them. In term of performance, I.pseudacorus seemed showed a preferable achievement.
The hydrological functioning of a constructed fen wetland watershed.
Ketcheson, Scott J; Price, Jonathan S; Sutton, Owen; Sutherland, George; Kessel, Eric; Petrone, Richard M
Mine reclamation requires the reconstruction of entire landforms and drainage systems. The hydrological regime of reclaimed landscapes will be a manifestation of the processes operating within the individual landforms that comprise it. Hydrology is the most important process regulating wetland function and development, via strong controls on chemical and biotic processes. Accordingly, this research addresses the growing and immediate need to understand the hydrological processes that operate within reconstructed landscapes following resource extraction. In this study, the function of a constructed fen watershed (the Nikanotee Fen watershed) is evaluated for the first two years following construction (2013-2014) and is assessed and discussed within the context of the construction-level design. The system design was capable of sustaining wet conditions within the Nikanotee Fen during the snow-free period in 2013 and 2014, with persistent ponded water in some areas. Evapotranspiration dominated the water fluxes from the system. These losses were partially offset by groundwater discharge from the upland aquifer, which demonstrated strong hydrologic connectivity with the fen in spite of most construction materials having lower than targeted saturated hydraulic conductivities. However, the variable surface infiltration rates and thick placement of a soil-capping layer constrained recharge to the upland aquifer, which remained below designed water contents in much of the upland. These findings indicate that it is possible to engineer the landscape to accommodate the hydrological functions of a fen peatland following surface oil sands extraction. Future research priorities should include understanding the storage and release of water within coarse-grained reclaimed landforms as well as evaluating the relative importance of external water sources and internal water conservation mechanisms for the viability of fen ecosystems over the longer-term. Copyright © 2017 Elsevier B
Changes in the Vegetation Cover in a Constructed Wetland at Argonne National Laboratory, Illinois
Bergman, C.L.; LaGory, K.
Wetlands are valuable resources that are disappearing at an alarming rate. Land development has resulted in the destruction of wetlands for approximately 200 years. To combat this destruction, the federal government passed legislation that requires no net loss of wetlands. The United States Army Corps of Engineers (USACE) is responsible for regulating wetland disturbances. In 1991, the USACE determined that the construction of the Advanced Photon Source at Argonne National Laboratory would damage three wetlands that had a total area of one acre. Argonne was required to create a wetland of equal acreage to replace the damaged wetlands. For the first five years after this wetland was created (1992-1996), the frequency of plant species, relative cover, and water depth was closely monitored. The wetland was not monitored again until 2002. In 2003, the vegetation cover data were again collected with a similar methodology to previous years. The plant species were sampled using quadrats at randomly selected locations along transects throughout the wetland. The fifty sampling locations were monitored once in June and percent cover of each of the plant species was determined for each plot. Furthermore, the extent of standing water in the wetland was measured. In 2003, 21 species of plants were found and identified. Eleven species dominated the wetland, among which were reed canary grass (Phalaris arundinacea), crown vetch (Coronilla varia), and Canada thistle (Cirsium arvense). These species are all non-native, invasive species. In the previous year, 30 species were found in the same wetland. The common species varied from the 2002 study but still had these non-native species in common. Reed canary grass and Canada thistle both increased by more than 100% from 2002. Unfortunately, the non-native species may be contributing to the loss of biodiversity in the wetland. In the future, control measures should be taken to ensure the establishment of more desired native species.
Monitoring iron and manganese diagenesis in constructed wetlands with continuous gradient gels
Edenborn, H.M.; Brickett, L.A.; Dvorak, D.H.; Edenborn, S.L.
Average removal rates for Fe and Mn in wetlands constructed for the treatment of coal mine drainage have been developed based on field observations, but few details are known about the spatial and temporal variation in metal diagenesis within these wetlands. The heterogeneous distribution of biological activity in constructed wetland sediments makes it difficult to assess the importance of specific diagenetic processes without taking large numbers of samples at great expense. In this study, continuous gradient gels were used to evaluate Pennsylvania. Continuous gradient gels provided rapid and detailed information on the regions of stability of Fe and Mn compounds within the wetland sediments. The resulting data were mapped and used to demonstrate how this technique can be used to assess the overall efficiency of constructed wetlands in the removal of Fe and Mn
[Evolution of Dissolved Organic Matter Properties in a Constructed Wetland of Xiao River, Hebei].
Ma, Li-na; Zhang, Hui; Tan, Wen-bing; Yu, Min-da; Huang, Zhi-gang; Gao, Ru-tai; Xi, Bei-dou; He, Xiao-song
The evolution of water DOC and COD, and the source, chemical structure, humification degree and redox of dissolved organic matter (DOM) in a constructed wetland of Xiao River, Hebei, was investigated by 3D excitation--emission matrix fluorescence spectroscopy coupled with ultraviolet spectroscopy and chemical reduction, in order to explore the geochemical processes and environmental effects of DOM. Although DOC contributes at least 60% to COD, its decrease in the constructed wetland is mainly caused by the more extensive degradation of elements N, H, S, and P than C in DOM, and 65% is contributed from the former. DOM is mainly consisted of microbial products based on proxies f470/520 and BIX, indicating that DOM in water is apparently affected by microbial degradation. The result based on PARAFAC model shows that DOM in the constructed wetland contains protein-like and humus-like components, and Fulvic- and humic-like components are relatively easier to degrade than protein-like components. Fulvic- and humic-like components undergo similar decomposition in the constructed wetland. A common source of chromophoric dissolved organic matter (CDOM) and fluorescent dissolved organic matter (FDOM) exists; both CDOM and FDOM are mainly composed of a humus-like material and do not exhibit selective degradation in the constructed wetland. The proxies E2 /E3, A240-400, r(A, C) and HIX in water have no changes after flowing into the constructed wetland, implying that the humification degree of DOM in water is hardly affected by wet constructed wetland. However, the constructed wetland environment is not only beneficial in forming the reduced state of DOM, but also facilitates the reduction of ferric. It can also improve the capability of DOM to function as an electron shuttle. This result may be related to the condition that the aromatic carbon of DOM can be stabilized well in the constructed wetland.
Removal of nutrients from septic tank effluent with baffle subsurface-flow constructed wetlands.
Cui, Lihua; Ouyang, Ying; Yang, Weizhi; Huang, Zhujian; Xu, Qiaoling; Yu, Guangwei
Three new baffle flow constructed wetlands (CWs), namely the baffle horizontal flow CW (Z1), baffle vertical flow CW (Z2) and baffle hybrid flow CW (Z3), along with one traditional horizontal subsurface flow CW (Z4) were designed to test the removal efficiency of nitrogen (N) and phosphorus (P) from the septic tank effluent under varying hydraulic retention times (HRTs). Results showed that the optimal HRT was two days for maximal removal of N and P from the septic tank effluent among the four CWs. At this HRT, the Z1, Z2, Z3 and Z4 CWs removed, respectively, 49.93, 58.50, 46.01 and 44.44% of TN as well as 87.82, 93.23, 95.97 and 91.30% of TP. Our study further revealed that the Z3 CW was the best design for overall removal of N and P from the septic tank effluent due to its hybrid flow directions with better oxygen supply inside the CW system. Copyright © 2015 Elsevier Ltd. All rights reserved.
Carbon sequestration in surface flow constructed wetland after 12 years of swine wastewater treatment
Constructed wetlands used for the treatment of swine wastewater may potentially sequester significant amounts of carbon. In past studies, we evaluated the treatment efficiency of wastewater in marsh-pond-marsh design wetland system. The functionality of this system was highly dependent on soil carbo...
Appropriate and sustainable wastewater management in developing countries by the use of constructed wetlands
Brix, Hans; Koottatep, Thammarat; Fryd, Ole
Constructed wetland systems for wastewater management may have great potential in developing countries as robust and decentralized solution. A case study from Koh Phi Phi island in Thailand where a constructed wetland systems was established after the destructions by the tsunami in 2004...... is described. The project includes a wastewater collection system for the main business area of the island, a pumping station, a multistage constructed wetland system, and a system for reuse of treated wastewater. The wastewater is treated to meet the Thai effluent standards for total suspended solids......, the system is only partly a success, mainly because no key-person or key-authority took responsibility for managing the system....
Microbial fuel cells for clogging assessment in constructed wetlands
Corbella, Clara; García, Joan; Puigagut, Jaume
Clogging in HSSF CW may result in a reduction of system's life-span or treatment efficiency. Current available techniques to assess the degree of clogging in HSSF CW are time consuming and cannot be applied on a continuous basis. Main objective of this work was to assess the potential applicability of microbial fuel cells for continuous clogging assessment in HSSF CW. To this aim, two replicates of a membrane-less microbial fuel cell (MFC) were built up and operated under laboratory conditions for five weeks. The MFC anode was gravel-based to simulate the filter media of HSSF CW. MFC were weekly loaded with sludge that had been accumulating for several years in a pilot HSSF CW treating domestic wastewater. Sludge loading ranged from ca. 20 kg TS·m"− "3 CW·year"− "1 at the beginning of the study period up to ca. 250 kg TS·m"− "3 CW·year"− "1 at the end of the study period. Sludge loading applied resulted in sludge accumulated within the MFC equivalent to a clogging degree ranging from 0.2 years (ca. 0.5 kg TS·m"–"3CW) to ca. 5 years (ca. 10 kg TS·m"–"3CW). Results showed that the electric charge was negatively correlated to the amount of sludge accumulated (degree of clogging). Electron transference (expressed as electric charge) almost ceased when accumulated sludge within the MFC was equivalent to ca. 5 years of clogging (ca. 10 kg TS·m"–"3CW). This result suggests that, although longer study periods under more realistic conditions shall be further performed, HSSF CW operated as a MFC has great potential for clogging assessment. - Highlights: • Microbial fuel cells are used as tool for clogging assessment in constructed wetlands. • Microbial fuel cells were loaded with sludge from constructed wetlands. • Sludge retained within the systems simulated a clogging time ranging from 0.2 to ca. 5 years. • Electrons transferred decreased potentially as function of sludge loading. • Microbial fuel cells have potential for clogging assessment
Corbella, Clara; García, Joan; Puigagut, Jaume, E-mail: jaume.puigagut@upc.edu
Clogging in HSSF CW may result in a reduction of system's life-span or treatment efficiency. Current available techniques to assess the degree of clogging in HSSF CW are time consuming and cannot be applied on a continuous basis. Main objective of this work was to assess the potential applicability of microbial fuel cells for continuous clogging assessment in HSSF CW. To this aim, two replicates of a membrane-less microbial fuel cell (MFC) were built up and operated under laboratory conditions for five weeks. The MFC anode was gravel-based to simulate the filter media of HSSF CW. MFC were weekly loaded with sludge that had been accumulating for several years in a pilot HSSF CW treating domestic wastewater. Sludge loading ranged from ca. 20 kg TS·m{sup −} {sup 3} CW·year{sup −} {sup 1} at the beginning of the study period up to ca. 250 kg TS·m{sup −} {sup 3} CW·year{sup −} {sup 1} at the end of the study period. Sludge loading applied resulted in sludge accumulated within the MFC equivalent to a clogging degree ranging from 0.2 years (ca. 0.5 kg TS·m{sup –3}CW) to ca. 5 years (ca. 10 kg TS·m{sup –3}CW). Results showed that the electric charge was negatively correlated to the amount of sludge accumulated (degree of clogging). Electron transference (expressed as electric charge) almost ceased when accumulated sludge within the MFC was equivalent to ca. 5 years of clogging (ca. 10 kg TS·m{sup –3}CW). This result suggests that, although longer study periods under more realistic conditions shall be further performed, HSSF CW operated as a MFC has great potential for clogging assessment. - Highlights: • Microbial fuel cells are used as tool for clogging assessment in constructed wetlands. • Microbial fuel cells were loaded with sludge from constructed wetlands. • Sludge retained within the systems simulated a clogging time ranging from 0.2 to ca. 5 years. • Electrons transferred decreased potentially as function of sludge loading. â
Water quality during storm events from two constructed wetlands receiving mine drainage
Stark, L.R.; Brooks, R.P.; Williams, F.M.; Stevens, S.E. Jr.; Davis, L.K.
Flow rates, pH, iron concentration, and manganese concentration were measured during several storm event at two constructed wetlands receiving mine water. During a substantial rain event, flow rates at both the wetland outlets surpassed flow rates at the wetland inlets, reflecting incident rainfall and differences in wetland area at the two sites. A significant positive correlation existed between local rainfall and outflow rates at the larger wetland, but not between rainfall and inflow rates. During storm events, outlet pH, relative to inlet pH, was slightly elevated at the larger wetland, and depressed at the smaller wetland. However, over the course of one year, rainfall was uncorrelated to outlet pH in the larger wetland. A substantial rain event at the smaller wetland resulted in a temporary elevation in outlet iron concentrations, with treatment efficiency reduced to near zero. However, in the larger wetland, outlet iron concentrations were not significantly affected by storm events. 14 refs., 7 figs., 4 tabs
Start-up of a free water surface constructed wetland for treating olive mill wastewater
Michailides Michail
Full Text Available An olive mill's existing evaporation pond was separated into five cells and transformed into a free water surface constructed wetland. The constructed wetland was used as a post-treatment stage for olive mill wastewater (OMW. Wastewater was previously treated by an aerobic trickling filter. The influent concentrations in the constructed wetland were 27400 mg.L-1, 4800 mg.L-1, 105 mg.L-1 and 770 mg.L-1 for COD, phenols, ortho-phosphate and TKN, respectively. Despite the rather high influent concentrations, the performance of the constructed wetland was very good since after the 60-day start-up operation period it achieved removal rates of about 94%, 95%, 95% and 98% for COD, phenols, ortho-phosphate and TKN, respectively. The major pollutant removal processes can be attributed to both biological processes occurring in the wetland and photo-oxidation. Laboratory-scale experiments with OMW from fifth cell of the wetland revealed that the net contribution of photo-oxidation after 112 hours of simulated solar radiation at 765 W/m2 (i.e. about 38 days of sunlight irradiation was 18% and 31% removal for COD and phenols, respectively. In the constructed wetland, the total removal reached 81% and 86% for COD and phenols, respectively, for the same time period (38 days.
Pre- and post-construction analysis of a wetland used for mine drainage control
Wise, K.M.; Mitsch, W.J.
A 0.39 ha constructed wetland in Athens County, Ohio is being evaluated for its ability to remove contaminants from acidic mine drainage. The wetland receives water flow from Lick run stream which is contaminated by two major abandoned underground mine seeps. The wetland effluent is then directed back into Lick Run, a tributary of the Hocking River. Data were collected 1.5 years prior to construction and 11 months following completion of the passive wetland system. Preconstruction data reported average spring quarter 1991 and 1992 iron concentrations in the stream at the future wetland influent and effluents sites to be 330 and 106 mg/l, while spring quarter 1993 showed iron levels at the wetland influent and effluent to be 64 and 3 mg/l, respectively. Iron removal percentages were 68% prior to the construction of the wetland and 95% following its completion. Preconstruction data were analyzed using a dynamic computer model and preliminary comparison with the first 11 months of the wetland data show the actual iron removal rates to be 4 g/m 2 day 1 compared to the predicted value of 6.5 g/m 2 day 1 (based on data collected from April 1991--March 1992, under similar hydrologic conditions)
Performance of hybrid constructed wetland systems for treating septic tank effluent.
Cui, Li-hua; Liu, Wen; Zhu, Xi-zhen; Ma, Mei; Huang, Xi-hua; Xia, Yan-yang
The integrated wetland systems were constructed by combining horizontal-flow and vertical-flow bed, and their purification efficiencies for septic tank effluent were detected when the hydraulic retention time (HRT) was 1 d, 3 d, 5 d under different seasons. The results showed that the removal efficiencies of the organics, phosphorus were steady in the hybrid systems, but the removal efficiency of total nitrogen was not steady due to high total nitrogen concentration in the septic tank effluent. The average removal rates of COD (chemical oxygen demand) were 89%, 87%, 83%, and 86% in summer, autumn, winter and spring, respectively, and it was up to 88%, 85%, 73%, and 74% for BOD5 (5 d biochemical oxygen demand) removal rate in four seasons. The average removal rates of TP (total phosphorous) could reach up to 97%, 98%, 95%, 98% in four seasons, but the removal rate of TN (total nitrogen) was very low. The results of this study also indicated that the capability of purification was the worst in winter. Cultivating with plants could improve the treated effluent quality from the hybrid systems. The results of the operation of the horizontal-flow and vertical-flow cells (hybrid systems) showed that the removal efficiencies of the organics, TP and TN in horizontal-flow and vertical-flow cells were improved significantly with the extension of HRT under the same season. The removal rate of 3 d HRT was obviously higher than that of 1 d HRT, and the removal rate of 5 d HRT was better than that of 3 d HRT, but the removal efficiency was not very obvious with the increment of HRT. Therefore, 3 d HRT might be recommended in the actual operation of the hybrid systems for economic and technical reasons.
Myriophyllum aquaticum Constructed Wetland Effectively Removes Nitrogen in Swine Wastewater
Haishu Sun
Full Text Available Removal of nitrogen (N is a critical aspect in the functioning of constructed wetlands (CWs, and the N treatment in CWs depends largely on the presence and activity of macrophytes and microorganisms. However, the effects of plants on microorganisms responsible for N removal are poorly understood. In this study, a three-stage surface flow CW was constructed in a pilot-scale within monospecies stands of Myriophyllum aquaticum to treat swine wastewater. Steady-state conditions were achieved throughout the 600-day operating period, and a high (98.3% average ammonia removal efficiency under a N loading rate of 9 kg ha-1 d-1 was observed. To determine whether this high efficiency was associated with the performance of active microbes, the abundance, structure, and interactions of microbial community were compared in the unvegetated and vegetated samples. Real-time quantitative polymerase chain reactions showed the abundances of nitrifying genes (archaeal and bacterial amoA and denitrifying genes (nirS, nirK, and nosZ were increased significantly by M. aquaticum in the sediments, and the strongest effects were observed for the archaeal amoA (218-fold and nirS genes (4620-fold. High-throughput sequencing of microbial 16S rRNA gene amplicons showed that M. aquaticum greatly changed the microbial community, and ammonium oxidizers (Nitrosospira and Nitrososphaera, nitrite-oxidizing bacteria (Nitrospira, and abundant denitrifiers including Rhodoplanes, Bradyrhizobium, and Hyphomicrobium, were enriched significantly in the sediments. The results of a canonical correspondence analysis and Mantle tests indicated that M. aquaticum may shift the sediment microbial community by changing the sediment chemical properties. The enriched nitrifiers and denitrifiers were distributed widely in the vegetated sediments, showing positive ecological associations among themselves and other bacteria based on phylogenetic molecular ecological networks.
Feasibility of constructed wetlands for removing chlorothalonil and chlorpyrifos from aqueous mixtures
Sherrard, R.M.; Bearr, J.S.; Murray-Gulde, C.L.; Rodgers, J.H.; Shah, Y.T.
Chlorpyrifos (an insecticide) and chlorothalonil (a fungicide) are transported in stormwater runoff and can be lethal to receiving aquatic system biota. This study determined removal rates of chlorpyrifos and chlorothalonil in simulated stormwater runoff treated in constructed wetland mesocosms. Using sentinel species, Ceriodaphnia dubia and Pimephales promelas, observed declines in toxicity of the simulated runoff after treatment were 98 and 100%, respectively. First order removal rates were 0.039/h for chlorpyrifos and 0.295/h for chlorothalonil in these experiments. Constructed wetland mesocosms were effective for decreasing concentrations of chlorpyrifos and chlorothalonil in simulated stormwater runoff, and decreasing P. promelas and C. dubia mortality resulting from these exposures. The results from this study indicate that constructed wetlands could be part of an efficient mitigation strategy for stormwater runoff containing these pesticides. - Constructed wetlands have potential for treatment of pesticide mixtures in stormwater runoff
Sherrard, R.M.; Bearr, J.S.; Murray-Gulde, C.L.; Rodgers, J.H.; Shah, Y.T
Chlorpyrifos (an insecticide) and chlorothalonil (a fungicide) are transported in stormwater runoff and can be lethal to receiving aquatic system biota. This study determined removal rates of chlorpyrifos and chlorothalonil in simulated stormwater runoff treated in constructed wetland mesocosms. Using sentinel species, Ceriodaphnia dubia and Pimephales promelas, observed declines in toxicity of the simulated runoff after treatment were 98 and 100%, respectively. First order removal rates were 0.039/h for chlorpyrifos and 0.295/h for chlorothalonil in these experiments. Constructed wetland mesocosms were effective for decreasing concentrations of chlorpyrifos and chlorothalonil in simulated stormwater runoff, and decreasing P. promelas and C. dubia mortality resulting from these exposures. The results from this study indicate that constructed wetlands could be part of an efficient mitigation strategy for stormwater runoff containing these pesticides. - Constructed wetlands have potential for treatment of pesticide mixtures in stormwater runoff.
Uptake and Translocation of Manganese by Native Tree Species in a Constructed Wetland Treating Landfill Leachates
A. Snow; Abdel E. Ghaly
A surface flow constructed wetland was used to treat stormwater runoff from surrounding watersheds which are comprised primarily of commercial properties and two former landfills. The uptake of manganese by red maple, white birch and red spruce trees growing under flooded soil conditions in the constructed wetland was compared to that of the same trees growing under well drained soil conditions in a nearby reference site. The seasonal variability of manganese and its distribution in different...
Uptake and Translocation of Iron by Native Tree Species In A Constructed Wetland Treating Landfill Leachates
A. Snow; Abdel E. Ghaly; R. Cote; A. M. Snow
A surface flow wetland was constructed in the Burnside Industrial Park, Dartmouth, Nova Scotia, to treat stormwater runoff from the surrounding watersheds which are comprised primarily of commercial properties and two former landfills. The objectives of this study were: (a) to compare the uptake of iron by red maple, white birch and red spruce trees growing under flooded soil conditions in the constructed wetland and well drained soil conditions in a nearby reference site, (b) to evaluate the...
[Impact of ecological protection construction on schistosomiasis transmission of Qionghai Lake wetland in Xichang City].
Feng, Zong-liang; Xu, Cong-min; Yin, Hong-zhi; Hua, Jiao; Lai, Yu-hua; Zhao, Lin; Wu, Zhong-ping
To understand the impact of Qionghai Lake wetland ecological protection construction on the prevalence of schistosomiasis, so as to provide the evidence for formulating the strategies for schistosomiasis control and prevention. A retrospective survey of the construction of Qionghai Lake wetland was performed, and eleven villages around the wetland were surveyed for schistosomiasis endemic situation. The influence of the wetland project on the schistosomiasis prevalence and Oncomelania hupensis snail status were investigated. Before the construction of Qionghai Lake wetland, the snail elimination and extended chemotherapy for residents was performed. After the project was finished, the roads and ditches were hardened. From 2009 to 2014, the schistosome infection rate of residents declined from 0.37% to 0. No schistosome infected snails were found and in recent 2 years, no snails were found. No mice were infected in the sentinel tests. The construction of Qionghai Lake wetland effectively eliminates snails, and interrupts the transmission of schistosomiasis. However, the environment of the wetland is more suitable for snail breeding, and therefore, the surveillance still should be strengthened.
Subsurface Treatment of Domestic Wastewater Using Single Domicile Constructed Wetlands
Aseltyne, T.; Steer, D.; Fraser, L.
Analysis of one year of input versus output water quality monitoring data from nine household wastewater treatment wetlands in western Ohio indicates that these systems substantially reduce effluent loads delivered to the local watershed. Overall performance as measured by output water quality improvement varies widely between the nine systems despite their close proximity and identical design. These three-cell systems (septic tank with 2 subsurface wetland cells) are found to reduce biological oxygen demand (BOD) 70-98%, fecal coliform 60-99.9%, NH3 29-97%, Phosphorus 21-99.9% and total suspended solids (TSS) up to 97%. NO3/NO2 readings were only taken at the second wetland cell, but show that NO3/NO2 levels are at 0.005-5.01 mg/l and well below the USEPA standards for discharge from a wetland. On average, the pH of the wastewater increases from 6.6 at the septic tank to 8.7 at the wetland output. Nearly all the monitoring data indicate clear decreases in nutrient loads and bacteria though individual systems are found to non-systematically fail to meet EPA discharge guidelines for one or more of the monitored loads. Preliminary analysis of the data indicates a decrease in overall efficiency of the wetlands in April that may be related to seasonal factors. These systems will be monitored for the next three years in order to relate changing performance trends to seasonal variability.
Demonstration of in situ-constructed horizontal soil containment barrier at Fernald
Pettit, P.J.; Ridenour, D.; Walker, J.; Saugier, K.
A new design of jet grouting tool that can be guided by horizontal well casings and that operates in the horizontal plane has been used for the in situ placement of grout and construction of a prototype horizontal barrier that is free of windows. Jet grouting techniques have been advanced to permit construction of horizontal barriers underneath contaminated soil without having to excavate or disturb the waste. The paper describes progress on the Fernald Environmental Restoration Management Corporation (FERMCO) In Situ Land Containment Project which is sponsored by the US Department of Energy's (DOE) Office of Technology Development (OTD) for DOE's Fernald Environmental Management Project (FEMP). The Fernald project is to demonstrate a novel, enabling technology for the controlled underground placement of horizontal panels of grout, and the joining of adjacent panels to construct practical, extensive barriers. Construction strategy, equipment mechanics and operating details of this new method are described
Effects of power-line construction on wetland vegetation in Massachusetts, USA
Nickerson, Norton H.; Dobberteen, Ross A.; Jarman, Nancy M.
Utility rights-of-way corridors through wetland areas generate long-term impacts from construction activities to these valuable ecosystems. Changes to and recovery of the vegetation communities of a cattail marsh, wooded swamp, and shrub/bog wetland were documented through measurements made each growing season for two years prior, five years following, and again on the tenth year after construction of a 345-kV transmission line. While both the cattail marsh and wooded swamp recovered within a few years, measures of plant community composition in the shrub/bog wetland were still lower, compared to controls, after ten years. Long-term investigations such as the one reported here help decrease uncertainty and provide valuable information for future decision making regarding construction of power utility lines through valuable and dwindling wetland resources.
Using decomposition kinetics to model the removal of mine water pollutants in constructed wetlands
Tarutis, W J; Unz, R F [Pennsylvania State University, University Park, PA (United States)
Although numerous mathematical models have been used to describe decomposition, few, if any, have been used to model the removal of pollutants in constructed wetlands. A steady state method based on decomposition kinetics and reaction stoichiometry has been developed which simulates the removal of ferrous iron entering wetlands constructed for mine drainage treatment. Input variables for the model include organic matter concentration, reaction rate coefficient, porosity and dry density, and hydraulic detection time. Application of the model assumes complete anaerobic conditions within the entire substrate profile, constant temperature, no additional organic matter input, and subsurface flow only. For these ideal conditions, model simulations indicate that wetlands constructed with readily decomposable substrates rich in organic carbon are initially capable of removing far greater amounts of iron than wetlands built with less biodegradable substrates. However, after three to five years of operation this difference becomes negligible. For acceptable long-term treatment performance, therefore, periodic additions of decomposable organic matter will be required.
Bioenergy production potential for aboveground biomass from a subtropical constructed wetland
Wang, Yi-Chung [Department of Forestry and Nature Conservation, Chinese Culture University, Taipei 11114 (China); Ko, Chun-Han [School of Forestry and Resource Conservation, National Taiwan University, Taipei 10617 (China); Bioenergy Research Center, National Taiwan University, Taipei 10617 (China); Chang, Fang-Chih [The Instrument Center, National Cheng Kung University, No.1, University Road, Tainan City 70101 (China); Chen, Pen-Yuan [Department of Landscape Architecture, National Chiayi University, Chiayi City 60004 (China); Liu, Tzu-Fen [School of Forestry and Resource Conservation, National Taiwan University, Taipei 10617 (China); Sheu, Yiong-Shing [Department of Water Quality Protection, Environmental Protection Administration, Executive Yuan, Taipei 10042 (China); Shih, Tzenge-Lien [Department of Chemistry, Tamkang University, Tamsui, Taipei 25137 (China); Teng, Chia-Ji [Environmental Protection Bureau, Taipei County Government, Taipei 22001 (China)
Wetland biomass has potentials for bioenergy production and carbon sequestration. Planted with multiple species macrophytes to promote biodiversity, the 3.29 ha constructed wetland has been treated 4000 cubic meter per day (CMD) domestic wastewater and urban runoff. This study investigated the seasonal variations of aboveground biomass of the constructed wetland, from March 2007 to March 2008. The overall aboveground biomass was 16,737 kg and total carbon content 6185 kg at the peak of aboveground accumulation for the system emergent macrophyte at September 2007. Typhoon Korsa flood this constructed wetland at October 2007, however, significant recovery for emergent macrophyte was observed without human intervention. Endemic Ludwigia sp. recovered much faster, compared to previously dominated typha. Self-recovery ability of the macrophyte community after typhoon validated the feasibility of biomass harvesting. Incinerating of 80% biomass harvested of experimental area in a nearby incineration plant could produce 11,846 kWh for one month. (author)
Application of the artificial intelligence to estimate the constructed wetland response to heavy metal removal
Elektorowicz, M. [Concordia Univ., Building, Civil and Environmental Engineering, Montreal, Quebec (Canada)]. E-mail: mariae@civil.concordia.ca; Balanzinski, M. [Ecole Polytechnique de Montreal, Mechnical Engineering, Montreal, Quebec (Canada); Qasaimeh, A. [Concordia Univ., Building, Civil and Environmental Engineering, Montreal, Quebec (Canada)
Current design approaches lack essential parameters necessary to evaluate the removal of metals contained in wastewater which is discharged to constructed wetlands. As a result, there is no guideline for an accurate design of constructed wetlands. An artificial intelligence approach was used to assess constructed wetland design. For this purpose concentrations of bioavailable mercury were evaluated in conditions where initial concentrations of inorganic mercury, chloride concentrations and pH values changed. Fuzzy knowledge base was built based on results obtained from previous investigations performed in a greenhouse for floating plants, and from computations for mercury speciation. The Fuzzy Decision Support System (FDSS) used the knowledge base to find parameters that permit to generate the highest amount of mercury available for plants. The findings of this research can be applied to wetlands and all natural processes where correlations between them are uncertain. (author)
Elektorowicz, M.; Balanzinski, M.; Qasaimeh, A.
Influence of environmental variables on the structure and composition of soil bacterial communities in natural and constructed wetlands.
Arroyo, Paula; Sáenz de Miera, Luis E; Ansola, Gemma
Bacteria are key players in wetland ecosystems, however many essential aspects regarding the ecology of wetland bacterial communities remain unknown. The present study characterizes soil bacterial communities from natural and constructed wetlands through the pyrosequencing of 16S rDNA genes in order to evaluate the influence of wetland variables on bacterial community composition and structure. The results show that the composition of soil bacterial communities was significantly associated with the wetland type (natural or constructed wetland), the type of environment (lagoon, Typha or Salix) and three continuous parameters (SOM, COD and TKN). However, no clear associations were observed with soil pH. Bacterial diversity values were significantly lower in the constructed wetland with the highest inlet nutrient concentrations. The abundances of particular metabolic groups were also related to wetland characteristics. Copyright © 2014 Elsevier B.V. All rights reserved.
A smart market for nutrient credit trading to incentivize wetland construction
Raffensperger, John F.; Prabodanie, R. A. Ranga; Kostel, Jill A.
Nutrient trading and constructed wetlands are widely discussed solutions to reduce nutrient pollution. Nutrient markets usually include agricultural nonpoint sources and municipal and industrial point sources, but these markets rarely include investors who construct wetlands to sell nutrient reduction credits. We propose a new market design for trading nutrient credits, with both point source and non-point source traders, explicitly incorporating the option of landowners to build nutrient removal wetlands. The proposed trading program is designed as a smart market with centralized clearing, done with an optimization. The market design addresses the varying impacts of runoff over space and time, and the lumpiness of wetland investments. We simulated the market for the Big Bureau Creek watershed in north-central Illinois. We found that the proposed smart market would incentivize wetland construction by assuring reasonable payments for the ecosystem services provided. The proposed market mechanism selects wetland locations strategically taking into account both the cost and nutrient removal efficiencies. The centralized market produces locational prices that would incentivize farmers to reduce nutrients, which is voluntary. As we illustrate, wetland builders' participation in nutrient trading would enable the point sources and environmental organizations to buy low cost nutrient credits.
Mitigation of two pyrethroid insecticides in a Mississippi Delta constructed wetland
Moore, M.T. [USDA Agricultural Research Service National Sedimentation Laboratory, Water Quality and Ecology Research Unit, PO Box 1157, 598 McElroy Drive, Oxford, MS 38655 (United States)], E-mail: matt.moore@ars.usda.gov; Cooper, C.M.; Smith, S.; Cullum, R.F.; Knight, S.S.; Locke, M.A.; Bennett, E.R. [USDA Agricultural Research Service National Sedimentation Laboratory, Water Quality and Ecology Research Unit, PO Box 1157, 598 McElroy Drive, Oxford, MS 38655 (United States)
Constructed wetlands are a suggested best management practice to help mitigate agricultural runoff before entering receiving aquatic ecosystems. A constructed wetland system (180 m x 30 m), comprising a sediment retention basin and two treatment cells, was used to determine the fate and transport of simulated runoff containing the pyrethroid insecticides lambda-cyhalothrin and cyfluthrin, as well as suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results showed 49 and 76% of the study's measured lambda-cyhalothrin and cyfluthrin masses were associated with vegetation, respectively. Based on conservative effects concentrations for invertebrates and regression analyses of maximum observed wetland aqueous concentrations, a wetland length of 215 m x 30 m width would be required to adequately mitigate 1% pesticide runoff from a 14 ha contributing area. Results of this experiment can be used to model future design specifications for constructed wetland mitigation of pyrethroid insecticides. - A wetland length of 215 m x 30 m mitigated pyrethroid runoff from a 14 ha field.
Moore, M.T.; Cooper, C.M.; Smith, S.; Cullum, R.F.; Knight, S.S.; Locke, M.A.; Bennett, E.R.
Constructed wetlands are a suggested best management practice to help mitigate agricultural runoff before entering receiving aquatic ecosystems. A constructed wetland system (180 m x 30 m), comprising a sediment retention basin and two treatment cells, was used to determine the fate and transport of simulated runoff containing the pyrethroid insecticides lambda-cyhalothrin and cyfluthrin, as well as suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results showed 49 and 76% of the study's measured lambda-cyhalothrin and cyfluthrin masses were associated with vegetation, respectively. Based on conservative effects concentrations for invertebrates and regression analyses of maximum observed wetland aqueous concentrations, a wetland length of 215 m x 30 m width would be required to adequately mitigate 1% pesticide runoff from a 14 ha contributing area. Results of this experiment can be used to model future design specifications for constructed wetland mitigation of pyrethroid insecticides. - A wetland length of 215 m x 30 m mitigated pyrethroid runoff from a 14 ha field
Performance of hybrid subsurface constructed wetland system for piggery wastewater treatment.
Zhang, X; Inoue, T; Kato, K; Harada, J; Izumoto, H; Wu, D; Sakuragi, H; Ietsugu, H; Sugawara, Y
The objective of this study was to evaluate performance of a hybrid constructed wetland (CW) built for high organic content piggery wastewater treatment in a cold region. The system consists of four vertical and one horizontal flow subsurface CWs. The wetland was built in 2009 and water quality was monitored from the outset. Average purification efficiency of this system was 95±5, 91±7, 89±8, 70±10, 84±15, 90±6, 99±2, and 93±16% for biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total carbon (TC), total nitrogen (TN), ammonium-N (NH4-N), total phosphorus (TP), total coliform (T. Coliform), and suspended solids (SS), respectively during August 2010-December 2013. Pollutant removal rate was 15±18 g m(-2) d(-1), 49±52 g m(-2) d(-1), 6±4 g m(-2) d(-1), 7±5 g m(-2) d(-1), and 1±1 g m(-2) d(-1) for BOD5, COD, TN, NH4-N, and TP, respectively. The removal efficiency of BOD5, COD, NH4-N, and SS improved yearly since the start of operation. With respect to removal of TN and TP, efficiency improved in the first three years but slightly declined in the fourth year. The system performed well during both warm and cold periods, but was more efficient in the warm period. The nitrate increase may be attributed to a low C/N ratio, due to limited availability of carbon required for denitrification.
Sediment accretion and carbon storage in constructed wetlands receiving water treated with metal-based coagulants
Stumpner, Elizabeth; Kraus, Tamara; Liang, Yan; Bachand, Sandra M.; Horwath, William R.; Bachand, Philip A.M.
In many regions of the world, subsidence of organic rich soils threatens levee stability and freshwater supply, and continued oxidative loss of organic matter contributes to greenhouse gas production. To counter subsidence in the Sacramento-San Joaquin Delta of northern California, we examined the feasibility of using constructed wetlands receiving drainage water treated with metal-based coagulants to accrete mineral material along with wetland biomass, while also sequestering carbon in wetland sediment. Nine field-scale wetlands were constructed which received local drainage water that was either untreated (control), or treated with polyaluminum chloride (PAC) or iron sulfate (FeSO4) coagulants. After 23 months of flooding and coagulant treatment, sediment samples were collected near the inlet, middle, and outlet of each wetland to determine vertical accretion rates, bulk density, sediment composition, and carbon sequestration rates. Wetlands treated with PAC had the highest and most spatially consistent vertical accretion rates (~6 cm year-1), while the FeSO4 wetlands had similarly high accretion rates near the inlet but rates similar to the untreated wetland (~1.5 cm year-1) at the middle and outlet sites. The composition of the newly accreted sediment in the PAC and FeSO4 treatments was high in the added metal (aluminum and iron, respectively), but the percent metal by weight was similar to native soils of California. As has been observed in other constructed wetlands, the newly accreted sediment material had lower bulk densities than the native soil material (0.04-0.10 g cm-3 versus 0.2-0.3 g cm-3), suggesting these materials will consolidate over time. Finally, this technology accelerated carbon burial, with rates in PAC treated wetland (0.63 kg C m-2 yr-1) over 2-fold greater than the untreated control (0.28 kg C m-2 yr-1). This study demonstrates the feasibility of using constructed wetlands treated with coagulants to reverse subsidence by accreting the
Nitrogen removal and greenhouse gas emissions from constructed wetlands receiving tile drainage water.
Groh, Tyler A; Gentry, Lowell E; David, Mark B
Loss of nitrate from agricultural lands to surface waters is an important issue, especially in areas that are extensively tile drained. To reduce these losses, a wide range of in-field and edge-of-field practices have been proposed, including constructed wetlands. We re-evaluated constructed wetlands established in 1994 that were previously studied for their effectiveness in removing nitrate from tile drainage water. Along with this re-evaluation, we measured the production and flux of greenhouse gases (GHGs) (CO, NO, and CH). The tile inlets and outlets of two wetlands were monitored for flow and N during the 2012 and 2013 water years. In addition, seepage rates of water and nitrate under the berm and through the riparian buffer strip were measured. Greenhouse gas emissions from the wetlands were measured using floating chambers (inundated fluxes) or static chambers (terrestrial fluxes). During this 2-yr study, the wetlands removed 56% of the total inlet nitrate load, likely through denitrification in the wetland. Some additional removal of nitrate occurred in seepage water by the riparian buffer strip along each berm (6.1% of the total inlet load, for a total nitrate removal of 62%). The dominant GHG emitted from the wetlands was CO, which represented 75 and 96% of the total GHG emissions during the two water years. The flux of NO contributed between 3.7 and 13% of the total cumulative GHG flux. Emissions of NO were 3.2 and 1.3% of the total nitrate removed from wetlands A and B, respectively. These wetlands continue to remove nitrate at rates similar to those measured after construction, with relatively little GHG gas loss. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
Nitrogen and COD Removal from Septic Tank Wastewater in Subsurface Flow Constructed Wetlands: Plants Effects.
Collison, R S; Grismer, M E
We evaluated subsurface flow (SSF) constructed wetland treatment performance with respect to organics (COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) wastewater as affected by the presence of plants, substrate "rock" cation exchange capacity (CEC), laboratory versus field conditions and use of synthetic as compared to actual domestic wastewater. This article considers the effects of plants on constructed wetland treatment in the field. Each constructed wetland system was comprised of two beds (2.6 m long by 0.28 m wide and deep filled with ~18 mm crushed lava rock) separated by an aeration tank connected in series. The lava rock had a porosity of ~47% and a CEC of 4 meq/100 gm. One pair of constructed wetland systems was planted with cattails in May 2008, while an adjacent pair of systems remained un-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each constructed wetland system and effluent samples were regularly collected and tested for COD and nitrogen species during four time periods spanning November 2008 through June 2009. These effluent concentrations were tested for statistical differences at the 95% level for individual time periods as well as the overall 6-month period. Organics removal from domestic wastewater was 78.8% and 76.1% in the planted and un-planted constructed wetland systems, respectively, while ammonium removal was 94.5% and 90.2%, respectively. Similarly, organics removal from the synthetic wastewater of equivalent strength was 88.8% and 90.1% for planted and un-planted constructed wetland systems, respectively, while ammonium removal was 96.9% and 97.3%, respectively.
Effect of climatic conditions, season and wastewater quality on contaminant removal efficiency of two experimental constructed wetlands in different regions of Spain.
Garfí, Marianna; Pedescoll, Anna; Bécares, Eloy; Hijosa-Valsero, María; Sidrach-Cardona, Ricardo; García, Joan
The aim of this study was to examine the effects of climate, season and wastewater quality on contaminant removal efficiency of constructed wetlands implemented in Mediterranean and continental-Mediterranean climate region of Spain. To this end, two experimental horizontal subsurface flow constructed wetlands located in Barcelona and León (Spain) were compared. The two constructed wetland systems had the same experimental set-up. Each wetland had a surface area of 2.95 m(2), a water depth of 25 cm and a granular medium of D(60)=7.3 mm, and was planted with Phragmites australis. Both systems were designed in order to operate with a maximum organic loading rate of 6 g(DBO) m(-2) d(-1). Experimental systems operated with a hydraulic loading rate of 28.5 and 98 mm d(-1) in Barcelona and León, respectively. Total suspended solids, biochemical oxygen demand and ammonium mass removal efficiencies followed seasonal trends, with higher values in the summer (97.4% vs. 97.8%; 97.1% vs. 96.2%; 99.9% vs. 88.9%, in Barcelona and León systems, respectively) than in the winter (83.5% vs. 74.4%; 73.2% vs. 60.6%; 19% vs. no net removal for ammonium in Barcelona and León systems, respectively). During the cold season, biochemical oxygen demand and ammonium removal were significantly higher in Barcelona system than in León, as a result of higher temperature and redox potential in Barcelona. During the warm season, statistical differences were observed only for ammonium removal. Results showed that horizontal subsurface flow constructed wetland is a successful technology for both regions considered, even if winter seemed to be a critical period for ammonium removal in continental climate regions. Copyright © 2012 Elsevier B.V. All rights reserved.
Coliform bacteria removal from sewage in constructed wetlands planted with Mentha aquatica.
Avelar, Fabiana F; de Matos, Antonio T; de Matos, Mateus P; Borges, Alisson C
The present study evaluated the performance of the species Mentha aquatica in constructed wetlands of horizontal subsurface flow (CW-HSSF) with regard to the removal of coliforms bacteria in an effluent from the primary treatment of sewage as well as to obtain adjustment parameters of the bacterial decay kinetic model along the length of the CW-HSSF. Therefore, four CW-HSSFs measuring 24.0 m x 1.0 m x 0.35 m were built and filled with number 0 gravel as the support medium to a height of 0.20m. Two of the CW-HSSFs were planted with the species M. aquatica, while the other two remained uncultivated. Cultivation of M. aquatica in CW-HSSF resulted in total coliforms (TC) and Escherichia coli (EC) removals from 0.9 to 1.3 log units greater than those obtained in the uncultivated experimental plots, for the hydraulic retention times (HRTs) of 4.5 and 6.0 days. For HRT ranged from 1.5 to 6.0 days, the highest removal efficiencies in counts of TC and EC were obtained when using longer HRT. The mathematical models evaluated showed good fit to average counts of TC and EC highlighting the modified first-order kinetic model with the inclusion of the power parameter in the HRT variable.
Nutrients removal by Typha latifolia and Cynodon spp. grown in constructed wetlands
Mateus Pimentel de Matos
Full Text Available The objective of this study was to evaluate the extraction capacity of two species when grown in constructed wetlands with subsurface horizontal flow (SACs for the treatment of swine wastewater (ARS. To this end, were built 8 SACs of 2.0 m x 0.5 m x 0.6 m, fiber glass, filled with 0.55 m of fine gravels. In SAC2; SAC4; SAC6 and SAC8 was cultivated cattail (Typha latifolia and in SAC3; SAC5; SAC7 and SAC9 was cultivated tifton-85 bermudagrass (Cynodon spp.. The SAC2 and SAC3, SAC4 and SAC5, SAC6 and SAC7 and SAC8 and SAC9 received 163, 327, 461 and 561 kg ha-1 day-1 of BOD, respectively. During the 120 days of the SACs monitoring, it was found that the cattail has not adapted to the conditions of exposure. The highest yields were obtained with the application of organic load average of 327 kg ha-1 day-1 of BOD. The tifton-85 was the plant species with the highest capacity to extract nutrients, getting to draw between 443 and 540, 86 and 99, 193 and 241, 0.77 and 2.17, and 1.21 and 3.68 kg ha-1 TKN, P, K, Cu and Zn, respectively, while cattail showed greater capacity to absorb sodium.
Multilayer Substrate Configuration Enhances Removal Efficiency of Pollutants in Constructed Wetlands
Shaoyuan Bai
Full Text Available This study aimed at optimizing horizontal subsurface flow constructed wetlands (CWs to improve hydraulic performance and pollutant removal efficiency. A groundwater modeling package (MODFLOW was used to optimize three design parameters (length-to-width ratio, inlet/outlet-to-length ratio, and substrate size configuration. Using the optimized parameters, three pilot-scale CWs were built to treat actual wastewater. For model validation, we used a tracer test to evaluate hydraulic performance, and investigated the pollutant spatial distributions and removal efficiencies. We conclude that MODFLOW is suitable for designing CWs, accurately predicting that increasing hydraulic conductivity from surface to bottom layers could improve performance. However, the effect of vegetation, which decreased the hydraulic conductivity of the surface layer, should be considered to improve simulation results. Multilayer substrate configuration, with increasing hydraulic conductivity from the surface to bottom layers, significantly increased pollutant removal compared with monolayer configuration. The spatial variation in pollutant transport and degradation through the filling substrate showed that the multilayer configuration was able to increase use of the available space and moderately reduced short-circuiting and dead zones. Thus, multilayer CWs had higher experimental retention times, effective volume fractions and hydraulic efficiencies, and lower short-circuiting compared with monolayer CWs operating under similar conditions.
Pharmaceutical removal in tropical subsurface flow constructed wetlands at varying hydraulic loading rates.
Zhang, Dong Qing; Gersberg, Richard M; Hua, Tao; Zhu, Junfei; Tuan, Nguyen Anh; Tan, Soon Keat
Determining the fate of emerging organic contaminants in an aquatic ecosystem is important for developing constructed wetlands (CWs) treatment technology. Experiments were carried out in subsurface flow CWs in Singapore to evaluate the fate and transport of eight pharmaceutical compounds. The CW system included three parallel horizontal subsurface flow CWs and three parallel unplanted beds fed continuously with synthetic wastewater at different hydraulic retention times (HRTs). The findings of the tests at 2-6 d HRTs showed that the pharmaceuticals could be categorized as (i) efficiently removed compounds with removal higher than 85% (ketoprofen and salicylic acid); (ii) moderately removed compounds with removal efficiencies between 50% and 85% (naproxen, ibuprofen and caffeine); and (iii) poorly removed compounds with efficiency rate lower than 50% (carbamazepine, diclofenac, and clofibric acid). Except for carbamazepine and salicylic acid, removal efficiencies of the selected pharmaceuticals showed significant (pcaffeine, ketoprofen and clofibric acid were found to follow first order decay kinetics with decay constants higher in the planted beds than the unplanted beds. Correlations between pharmaceutical removal efficiencies and log K(ow) were not significant (p>0.05), implying that their removal is not well related to the compound's hydrophobicity. Copyright © 2011 Elsevier Ltd. All rights reserved.
Treating urban sewage using constructed wetlands; Depuracion de aguas residuales urbanas mediante humedales contruidos
Garcia, J. [ETS Camins, Canals i Ports. UPC. Barcelona (Spain); Ruiz, A. [Biologa. Barcelona. (Spain); Junqueras, X. [Biologo. Barcelona (Spain)
Constructed wetlands are a low-cost alternative for treating sewage from small urbanized areas. The ``Can Massaguer`` children`s holiday home has a 230 m``2 subsurface flow wetland for secondary treatment of the sewage generated by 130 people. The system comprises two porous substrate beds with macrophytes (ditch reed, Phragmites australis) and entry and exit units. Its high purification performance and nil running costs make it ideal for treating wastewaters from small built-up areas. (Author)
Land characterisation for soil-based constructed wetlands: Adapting investigation methods to design objectives
Petitjean, A.; Forquet, N.; Choubert, J.M.; Coquery, M; Bouyer, M.; Boutin, C.
Buffer zones between wastewater treatment plants and receiving water bodies have recently gained interest in France. These soil-based constructed wetland (SBCW) systems receive treated wastewater and may have various designs aiming to mimic 'natural' wetlands. Research is needed to assess the treatment efficiency of such systems. To this aim, a comprehensive study is carried out to understand the fate of water, conventional pollutants (suspended solids, organic carbon, ammonium, and phosph...
Environmental effect of constructed wetland as biofuel production system
Liu, Dong
Being as a renewable energy, biofuel has attracted worldwide attention. Clean biofuel production is an effective way to mitigate global climate change and energy crisis. Biofuel may offer a promising alternative to fossil fuels, but serious concerns arise about the adverse greenhouse gas consequences from using nitrogen fertilizers. Waste-nitrogen recycling is an attractive idea. Here we advocate a win-win approach to biofuel production which takes advantage of excessive nitrogen in domestic wastewater treated via constructed wetland (CW) in China. This study will carry on environmental effect analysis of CW as a biomass generation system through field surveys and controllable simulated experiments. This study intends to evaluate net energy balance, net greenhouse effect potential and ecosystem service of CW as biomass generation system, and make comparation with traditional wastewater treatment plant and other biofuel production systems. This study can provide a innovation mode in order to solve the dilemma between energy crops competed crops on production land and excessive nitrogen fertilizer of our traditional energy plant production. Data both from our experimental CWs in China and other researches on comparable CWs worldwide showed that the biomass energy yield of CWs can reach 182.3 GJ ha-1 yr-1, which was two to eight times higher than current biofuel-production systems. Energy output from CW was ˜137% greater than energy input for biofuel production. If CWs are designed with specific goal of biofuel production, biofuel production can be greatly enhanced through the optimization of N supply, hydraulic structures, and species selection in CWs. Assuming that 2.0 Tg (1 Tg = 1012 g) waste nitrogen contained in domestic wastewater is treated by CWs, biofuel production can account for 1.2% of national gasoline consumption in China. The proportion would increase to 6.7% if extra nitrogen (9.5 Tg) from industrial wastewater and agricultural runoff was included
Simulation of Constructed Wetland in treating Wastewater using Fuzzy Logic Technique
Sudarsan, J. S.; Subramani, Sheekha; Rajan, Rajitha J.; Shah, Isha; Nithiyanantham, S.
Constructed wetlands act as a natural alternative to conventional methods of wastewater treatment. CW are found effective in wastewater containing inorganic matter, organic matter, toxic compounds, metals, nitrogen, phosphorous, heavy metals, organic chemicals, and pathogens. The treatment efficiency by the adaptation of CWs in treatment process is achieved by a complex interaction between plants, microorganisms, soil matrix and substances in the wastewater. Constructed wetland treatment systems are engineered systems designed in such a manner that it could take advantages of those processes occurring in natural wetlands in treating the wastewater concerned, but in a more controlled environment. Petrochemical wastewater was the type of wastewater taken for the study. Characteristics of petrochemical wastewater mainly oil, Biological Oxygen Demand (BOD) and Chemical oxygen demand (COD) were selected for treatment in constructed wetland as they are predominant in petrochemical wastewater. The conventional methods followed in the treatment are chemical and biological treatment. In this study, a fuzzy model for water quality assessment has been developed and water quality index value was obtained. The experiment conducted and further analysis using fuzzy logic indicated that interpretation of certain imprecise data can be improved within fuzzy inference system (FIS). Based on the analysis, we could observe that Typha sp contained wetland cell showed greater efficiency in removal of parameters such as COD and BOD than Phragmites sp. wetland cell.
[Correlation of substrate structure and hydraulic characteristics in subsurface flow constructed wetlands].
Bai, Shao-Yuan; Song, Zhi-Xin; Ding, Yan-Li; You, Shao-Hong; He, Shan
The correlation of substrate structure and hydraulic characteristics was studied by numerical simulation combined with experimental method. The numerical simulation results showed that the permeability coefficient of matrix had a great influence on hydraulic efficiency in subsurface flow constructed wetlands. The filler with a high permeability coefficient had a worse flow field distribution in the constructed wetland with single layer structure. The layered substrate structure with the filler permeability coefficient increased from surface to bottom could avoid the short-circuited flow and dead-zones, and thus, increased the hydraulic efficiency. Two parallel pilot-scale constructed wetlands were built according to the numerical simulation results, and tracer experiments were conducted to validate the simulation results. The tracer experiment result showed that hydraulic characteristics in the layered constructed wetland were obviously better than that in the single layer system, and the substrate effective utilization rates were 0.87 and 0.49, respectively. It was appeared that numerical simulation would be favorable for substrate structure optimization in subsurface flow constructed wetlands.
Effects of plant species on soil microbial processes and CH4 emission from constructed wetlands
Wang, Yanhua; Yang, Hao; Ye, Chun; Chen, Xia; Xie, Biao; Huang, Changchun; Zhang, Jixiang; Xu, Meina
Methane (CH 4 ) emission from constructed wetland has raised environmental concern. This study evaluated the influence of mono and polyculture constructed wetland and seasonal variation on CH 4 fluxes. Methane emission data showed large temporal variation ranging from 0 to 249.29 mg CH 4 m −2 h −1 . Results indicated that the highest CH 4 flux was obtained in the polyculture system, planted with Phragmites australis, Zizania latifolia and Typha latifolia, reflecting polyculture system could stimulate CH 4 emission. FISH analysis showed the higher amount of methanotrophs in the profile of Z. latifolia in both mono and polyculture systems. The highest methanogens amount and relatively lower methanotrophs amount in the profile of polyculture system were obtained. The results support the characteristics of CH 4 fluxes. The polyculture constructed wetland has the higher potential of global warming. -- Highlights: ► The polyculture constructed wetland has the higher contribution to CH 4 emission. ► The CH 4 –C conversion ranged from 0 to 3.7%. ► The Z. latifolia played important roles in methanotrophs growth and CH 4 consumption. ► Major influence of T-N, TOC and plant cover on CH 4 emission was obtained. -- The polyculture constructed wetland has the higher contribution to global warming
Constructed Wetlands for Treatment of Combined Sewer Overflow in the US: A Review of Design Challenges and Application Status
Wendong Tao
Full Text Available As combined sewer systems and centralized wastewater treatment facilities age, many communities in the world are challenged by management of combined sewer overflow (CSO. Constructed wetlands are considered to be one of the green infrastructure solutions to CSOs in the US. Despite the wide application of constructed wetlands to different types of wastewaters, the stochastic and intermittent nature of CSO presents challenges for design and performance assessment of constructed wetlands. This paper reviews the application status of CSO constructed wetlands in the US, assesses the benefits of CSO constructed wetlands, identifies challenges to designing CSO constructed wetlands, and proposes design considerations. This review finds that constructed wetlands are effective in CSO treatment and relatively less expensive to build than comparable grey infrastructure. Constructed wetlands not only remove pollutants, but also mitigate the event-associated flow regime. The design challenges include incorporating considerations of green infrastructure into permit requirements, determining design capacity for highly variable flows, requiring pretreatment, and needing adaptive design and intensive monitoring. Simultaneous monitoring of flow rate and water quality at both the inflow and outflow of CSO constructed wetlands is required for performance assessment and needed to support design, but is rarely available.
Ceriodaphnia and Chironomus in situ toxicity tests assessing the wastewater treatment efficacy of constructed wetlands
Barjaktarovic, L.; Nix, P.; Gulley, J.
In situ toxicity tests were designed for Ceriodaphnia dubia and Chironomus tentans as part of a larger study designed to assess the effectiveness of constructed wetlands for the treatment of wastewater produced by oil production at Suncor OSG. The artificial wetlands were 50m long by 3m wide, with three replicates of the control and the treatment. Each wetland had four sample sites equidistant along its length, creating a gradient of treatment from site A being the most toxic to site D being the least toxic. Each test was conducted twice during the summer of 1994. Both the Ceriodaphnia and Chironomus test cages were a flow through design to allow for maximal exposure to the water within the wetlands. Mortality and reproduction were used as endpoints for Ceriodaphnia, whereas mortality and growth were used as endpoints for the Chironomus test. Test durations were fifteen and ten days respectively. Chironomus had very high mortality along the entire wetlands whereas Ceriodaphnia survival and fecundity increased along the length of the treatment wetlands. Both organisms had low mortality and high growth/fecundity in the control wetlands
An assessment of potential hydrologic and ecologic impacts of constructing mitigation wetlands, Rifle, Colorado, UMTRA project sites
This-assessment examines the consequences and risks that could result from the proposed construction of mitigation wetlands at the New and Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) Project sites near Rifle, Colorado. Remediation of surface contamination at those sites is now under way. Preexisting wetlands at or near the Old and New Rifle sites have been cleaned up, resulting in the loss of 0.7 and 10.5 wetland acres (ac) (0.28 and 4.2 hectares [ha]) respectively. Another 9.9 ac (4.0 ha) of wetlands are in the area of windblown contamination west of the New Rifle site. The US Army Corps of Engineers (USACE) has jurisdiction over the remediated wetlands. Before remedial action began, and before any wetlands were eliminated, the USACE issued a Section 404 Permit that included a mitigation plan for the wetlands to be lost. The mitigation plan calls for 34.2 ac (1 3.8 ha) of wetlands to be constructed at the south end and to the west of the New Rifle site. The mitigation wetlands would be constructed over and in the contaminated alluvial aquifer at the New Rifle site. As a result of the hydrologic characteristics of this aquifer, contaminated ground water would be expected to enter the environment through the proposed wetlands. A preliminary assessment was therefore required to assess any potential ecological risks associated with constructing the mitigation wetlands at the proposed location
Improving domestic wastewater treatment efficiency with constructed wetland microbial fuel cells: Influence of anode material and external resistance.
Corbella, Clara; Puigagut, Jaume
For the past few years, there has been an increasing interest in the operation of constructed wetlands as microbial fuel cells (CW-MFCs) for both the improvement of wastewater treatment efficiency and the production of energy. However, there is still scarce information on design and operation aspects to maximize CW-MFCs efficiency, especially for the treatment of real domestic wastewater. The aim of this study was to quantify the extent of treatment efficiency improvement carried out by membrane-less MFCs simulating a core of a shallow un-planted horizontal subsurface flow constructed wetland. The influence of the external resistance (50, 220, 402, 604 and 1000Ω) and the anode material (graphite and gravel) on treatment efficiency improvement were addressed. To this purpose, 6 lab-scale membrane-less MFCs were set-up and loaded in batch mode with domestic wastewater for 13weeks. Results showed that 220Ω was the best operation condition for maximising MFCs treatment efficiency, regardless the anode material employed. Gravel-based anode MFCs operated at closed circuit showed ca. 18%, 15%, 31% and 25% lower effluent concentration than unconnected MFCs to the COD, TOC, PO 4 -3 and NH 4 + -N, respectively. Main conclusion of the present work is that constructed wetlands operated as MFCs is a promising strategy to improve domestic wastewater treatment efficiency. However, further studies at pilot scale under more realistic conditions (such as planted systems operated under continuous mode) shall be performed to confirm the findings here reported. Copyright © 2018 Elsevier B.V. All rights reserved.
Effect of different plant species in pilot constructed wetlands for wastewater reuse in agriculture
Salvatore Barbagallo
Full Text Available In this paper the first results of an experiment carried out in Southern Italy (Sicily on the evapotranspiration (ET and removal in constructed wetlands with five plant species are presented. The pilot plant used for this study is made of twelve horizontal sub-surface flow constructed wetlands (each with a surface area of 4.5 m2 functioning in parallel, and it is used for tertiary treatment of part of the effluents from a conventional municipal wastewater treatment plant (trickling filter. Two beds are unplanted (control while ten beds are planted with five different macrophyte species: Cyperus papyrus, Vetiveria zizanoides, Miscanthus x giganteus, Arundo donax and Phragmites australis (i.e., every specie is planted in two beds to have a replication. The influent flow rate is measured in continuous by an electronic flow meter. The effluent is evaluated by an automatic system that measure the discharged volume for each bed. Physical, chemical and microbiological analyses were carried out on wastewater samples collected at the inlet of CW plant and at the outlet of the twelve beds. An automatic weather station is installed close to the experimental plant, measuring air temperature, wind speed and direction, rainfall, global radiation, relative humidity. This allows to calculate the reference Evapotranspiration (ET0 with the Penman-Monteith formula, while the ET of different plant species is measured through the water balance of the beds. The first results show no great differences in the mean removal performances of the different plant species for TSS, COD and E.coli, ranged from, respectively, 82% to 88%, 60% to 64% and 2.7 to 3.1 Ulog. The average removal efficiency of nutrient (64% for TN; 61 for NH4-N, 31% for PO4-P in the P.australis beds was higher than that other beds. From April to November 2012 ET measured for plant species were completely different from ET0 and ETcontrol, underlining the strong effect of vegetation. The cumulative
Treatment of atrazine in nursery irrigation runoff by a constructed wetland.
Runes, Heather B; Jenkins, Jeffrey J; Moore, James A; Bottomley, Peter J; Wilson, Bruce D
To investigate the treatment capability of a surface flow wetland at a container nursery near Portland, Oregon, atrazine was introduced during simulated runoff events. Treatment efficiency was evaluated as the percent atrazine recovered (as percent of applied) in the water column at the wetland's outlet. Atrazine treatment efficiency at the outlet of the constructed wetland during a 7-d period ranged from 18-24% in 1998 (experiments 1-3) and 16-17% in 1999 (experiments 4 and 5). Changes in total flow, or frequency and intensity of runoff events did not affect treatment. For experiment 6 in 1999, where the amount, frequency, and duration of runoff events exceeded all other experiments, treatment was compromised. For all experiments, deethylatrazine (DEA) and deisopropylatrazine (DIA) accounted for 13-21% of the initial application. Hydroxyatrazine (HA) was rarely detected in the water. Organic carbon adsorption coefficients (Koc) were determined from batch equilibrium sorption isotherms with wetland sediment, and they decreased in the order of HA > DIA > atrazine > DEA. Static water-sediment column experiments indicated that sorption is an important mechanism for atrazine loss from water passing through the constructed wetland. The results of the MPN assay indicated the existence in the wetland of a low-density population of microorganisms with the potential to mineralize atrazine's ethyl side chain.
Chromium fate in constructed wetlands treating tannery wastewaters.
Dotro, Gabriela; Palazolo, Paul; Larsen, Daniel
Nine experimental wetlands were built to determine chromium partitioning inside systems treating tannery wastewaters. Results showed 5-day biochemical oxygen demand and chromium removals of 95 to 99% and 90 to 99%, respectively. The majority of chromium was found in association with media (96 to 98%), followed by effluents (2.9 to 3.9%), and the least was found in plant parts (0.1%). Chemical speciation modeling of solutions and scanning electron microscope analysis suggest two potential chromium removal mechanisms--sorption/coprecipitation with iron hydroxides or oxyhydroxides and biomass sorption. The release of the majority of chromium in the iron- and organic-bound phases during sequential extractions supports the proposed dominant removal mechanisms. The use of a mixture of peat and gravel resulted in lower removal efficiencies and stronger partitioning in organic phases during sequential extractions. Chromium was efficiently removed by wetlands, retained through chemical and biological processes. Future research will focus on further exploring removal mechanisms and proposing management strategies for the chromium-containing wetland media.
The potential use of constructed wetlands in a recirculating aquaculture system for shrimp culture
Lin, Y.-F.; Jing, S.-R.; Lee, D.-Y.
Constructed wetlands improved water qualities and consequently increased the shrimp growth and survival in a recirculating system. - A pilot-scale constructed wetland unit, consisting of free water surface (FWS) and subsurface flow (SF) constructed wetlands arranged in series, was integrated into an outdoor recirculating aquaculture system (RAS) for culturing Pacific white shrimp (Litopenaeus vannamei). This study evaluated the performance of the wetland unit in treating the recirculating wastewater and examined the effect of improvement in water quality of the culture tank on the growth and survival of shrimp postlarvae. During an 80-day culture period, the wetland unit operated at a mean hydraulic loading rate of 0.3 m/day and effectively reduced the influent concentrations of 5-day biochemical oxygen demand (BOD 5 , 24%), suspended solids (SS, 71%), chlorophyll a (chl-a, 88%), total ammonium (TAN, 57%), nitrite nitrogen (NO 2 -N, 90%) and nitrate nitrogen (NO 3 -N, 68%). Phosphate (PO 4 -P) reduction was the least efficient (5.4%). The concentrations of SS, Chl-a, turbidity and NO 3 -N in the culture tank water in RAS were significantly (P≤0.05) lower than those in a control aquaculture system (CAS) that simulated static pond culture without wetland treatment. However, no significant difference (P≤0.05) in BOD 5 , TAN and NO 2 -N was found between the two systems. At the end of the study, the harvest results showed that shrimp weight and survival rate in the RAS (3.8±1.8 g/shrimp and 90%) significantly (P≤0.01) exceeded those in the CAS (2.3±1.5 g/shrimp and 71%). This study concludes that constructed wetlands can improve the water quality and provide a good culture environment, consequently increasing the shrimp growth and survival without water exchange, in a recirculating system
Lin, Y.-F.; Jing, S.-R.; Lee, D.-Y
Constructed wetlands improved water qualities and consequently increased the shrimp growth and survival in a recirculating system. - A pilot-scale constructed wetland unit, consisting of free water surface (FWS) and subsurface flow (SF) constructed wetlands arranged in series, was integrated into an outdoor recirculating aquaculture system (RAS) for culturing Pacific white shrimp (Litopenaeus vannamei). This study evaluated the performance of the wetland unit in treating the recirculating wastewater and examined the effect of improvement in water quality of the culture tank on the growth and survival of shrimp postlarvae. During an 80-day culture period, the wetland unit operated at a mean hydraulic loading rate of 0.3 m/day and effectively reduced the influent concentrations of 5-day biochemical oxygen demand (BOD{sub 5}, 24%), suspended solids (SS, 71%), chlorophyll a (chl-a, 88%), total ammonium (TAN, 57%), nitrite nitrogen (NO{sub 2}-N, 90%) and nitrate nitrogen (NO{sub 3}-N, 68%). Phosphate (PO{sub 4}-P) reduction was the least efficient (5.4%). The concentrations of SS, Chl-a, turbidity and NO{sub 3}-N in the culture tank water in RAS were significantly (P{<=}0.05) lower than those in a control aquaculture system (CAS) that simulated static pond culture without wetland treatment. However, no significant difference (P{<=}0.05) in BOD{sub 5}, TAN and NO{sub 2}-N was found between the two systems. At the end of the study, the harvest results showed that shrimp weight and survival rate in the RAS (3.8{+-}1.8 g/shrimp and 90%) significantly (P{<=}0.01) exceeded those in the CAS (2.3{+-}1.5 g/shrimp and 71%). This study concludes that constructed wetlands can improve the water quality and provide a good culture environment, consequently increasing the shrimp growth and survival without water exchange, in a recirculating system.
The influence of urbanisation on macroinvertebrate biodiversity in constructed stormwater wetlands.
Mackintosh, Teresa J; Davis, Jenny A; Thompson, Ross M
The construction of wetlands in urban environments is primarily carried out to assist in the removal of contaminants from wastewaters; however, these wetlands have the added benefit of providing habitat for aquatic invertebrates, fish and waterbirds. Stormwater quantity and quality is directly related to impervious area (roads, sealed areas, roofs) in the catchment. As a consequence, it would be expected that impervious area would be related to contaminant load and biodiversity in receiving waters such as urban wetlands. This study aimed to establish whether the degree of urbanisation and its associated changes to stormwater runoff affected macroinvertebrate richness and abundance within constructed wetlands. Urban wetlands in Melbourne's west and south east were sampled along a gradient of urbanisation. There was a significant negative relationship between total imperviousness (TI) and the abundance of aquatic invertebrates detected for sites in the west, but not in the south east. However macroinvertebrate communities were relatively homogenous both within and between all study wetlands. Chironomidae (non-biting midges) was the most abundant family recorded at the majority of sites. Chironomids are able to tolerate a wide array of environmental conditions, including eutrophic and anoxic conditions. Their prevalence suggests that water quality is impaired in these systems, regardless of degree of urbanisation, although the causal mechanism is unclear. These results show some dependency between receiving wetland condition and the degree of urbanisation of the catchment, but suggest that other factors may be as important in determining the value of urban wetlands as habitat for wildlife. Copyright © 2015 Elsevier B.V. All rights reserved.
The use of constructed wetlands in the treatment of acid mine drainage
Perry, A.; Kleinmann, R.L.P.
US government regulations require that all effluents from industrial operations, including mining, meet certain water quality standards. Constructed wetlands have proven to be useful in helping to attain those standards. Application of this biotechnology to mine water drainage can reduce water treatment costs and improve water quality in streams and rivers adversely affected by acidic mine water drainage from abandoned mines. Over 400 constructed wetland water treatment systems have been built on mined lands largely as a result of research by the US Bureau of Mines. Wetlands are passive biological treatment systems that are relatively inexpensive to construct and require minimal maintenance. Chemical treatment costs are reduced sufficiently to repay the cost of construction in less than a year. The mine waste water is typically treated in a series of excavated ponds that resemble small marsh areas. The ponds are engineered to facilitate bacterial oxidation of iron. Ideally, the water then flows through a composted organic substrate supporting a population of sulphate-reducing bacteria which raises the pH. Constructed wetlands in the USA are described - their history, functions, construction methodologies, applicabilities, limitations and costs. (author). 26 refs, 2 figs
Perry, A [Department of the Interior, Washington, DC (United States). Bureau of Mines; Kleinmann, R L.P. [Department of the Interior, Pittsburgh, PA (United States). Bureau of Mines
US government regulations require that all effluents from industrial operations, including mining, meet certain water quality standards. Constructed wetlands have proven to be useful in helping to attain those standards. Application of this biotechnology to mine water drainage can reduce water treatment costs and improve water quality in streams and rivers adversely affected by acidic mine water drainage from abandoned mines. Over 400 constructed wetland water treatment systems have been built on mined lands largely as a result of research by the US Bureau of Mines. Wetlands are passive biological treatment systems that are relatively inexpensive to construct and require minimal maintenance. Chemical treatment costs are reduced sufficiently to repay the cost of construction in less than a year. The mine waste water is typically treated in a series of excavated ponds that resemble small marsh areas. The ponds are engineered to facilitate bacterial oxidation of iron. Ideally, the water then flows through a composted organic substrate supporting a population of sulphate-reducing bacteria which raises the pH. Constructed wetlands in the USA are described - their history, functions, construction methodologies, applicabilities, limitations and costs. (author). 26 refs, 2 figs.
Phosphorus retention in a newly constructed wetland receiving agricultural tile drainage water.
Kynkäänniemi, Pia; Ulén, Barbro; Torstensson, Gunnar; Tonderski, Karin S
One measure used in Sweden to mitigate eutrophication of waters is the construction of small wetlands (free water surface wetland for phosphorus retention [P wetlands]) to trap particulate phosphorus (PP) transported in ditches and streams. This study evaluated P retention dynamics in a newly constructed P wetland serving a 26-ha agricultural catchment with clay soil. Flow-proportional composite water samples were collected at the wetland inlet and outlet over 2 yr (2010-2011) and analyzed for total P (TP), dissolved P (DP), particulate P (PP), and total suspended solids (TSS). Both winters had unusually long periods of snow accumulation, and additional time-proportional water samples were frequently collected during snowmelt. Inflow TP and DP concentrations varied greatly (0.02-1.09 mg L) during the sampling period. During snowmelt in 2010, there was a daily oscillation in P concentration and water flow in line with air temperature variations. Outflow P concentrations were generally lower than inflow concentrations, with net P losses observed only in August and December 2010. On an annual basis, the wetland acted as a net P sink, with mean specific retention of 69 kg TP, 17 kg DP, and 30 t TSS ha yr, corresponding to a reduction in losses of 0.22 kg TP ha yr from the agricultural catchment. Relative retention was high (36% TP, 9% DP, and 36% TSS), indicating that small constructed wetlands (0.3% of catchment area) can substantially reduce P loads from agricultural clay soils with moderately undulating topography. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
Ecological effects of pipeline construction through deciduous forested wetlands, Midland County, Michigan
Zellmer, S.D.; Rastorfer, J.R.; Van Dyke, G.D.
Implementation of recent federal and state regulations promulgated to protect wetlands makes information on effects of gas pipeline rights-of-way (ROWs) in wetlands essential to the gas pipeline industry. This study is designed to record vegetational changes induced by the construction of a large-diameter gas pipeline through deciduous forested wetlands. Two second-growth forested wetland sites mapped as Lenawee soils, one mature and one subjected to recent selective logging, were selected in Midland County, Michigan. Changes in the adjacent forest and successional development on the ROW are being documented. Cover-class estimates are being made for understory and ROW plant species using 1 x1-m quadrats. Counts are also being made for all woody species with stems < 2 cm in diameter at breast height (dbh) in the same plots used for cover-class estimates. Individual stem diameters and species counts are being recorded for all woody understory and overstory plants with stems ≥2 cm dbh in 10 x 10-m plots. Although analyses of the data have not been completed, preliminary analyses indicate that some destruction of vegetation at the ROW forest edge may have been avoidable during pipeline construction. Rapid regrowth of many native wetland plant species on the ROW occurred because remnants of native vegetation and soil-bearing propagules of existing species survived on the ROW after pipeline construction and seeding operations. 91 refs., 11 figs., 3 tabs
Performance of a constructed wetland treating intensive shrimp aquaculture wastewater under high hydraulic loading rate
Lin, Y.-F.; Jing, S.-R.; Lee, D.-Y.; Chang, Y.-F.; Chen, Y.-M.; Shih, K.-C.
A water treatment unit, mainly consisting of free water surface (FWS) and subsurface flow (SF) constructed wetland cells, was integrated into a commercial-scale recirculating aquaculture system for intensive shrimp culture. This study investigated performance of the treatment wetlands for controlling water quality. The results showed that the FWS-SF cells effectively removed total suspended solids (55-66%), 5-day biochemical oxygen demand (37-54%), total ammonia (64-66%) and nitrite (83-94%) from the recirculating water under high hydraulic loading rates (1.57-1.95 m/day). This led to a water quality that was suitable for shrimp culture and effluent that always satisfied the discharge standards. The area ratios of wetlands to culture tank being demonstrated (0.43) and calculated (0.096) in this study were both significantly lower than the reported values. Accordingly, a constructed wetland was technically and economically feasible for managing water quality of an intensive aquaculture system. - A constructed wetland was found to be technically and economically feasible for managing water quality of an intensive recirculating aquaculture system
Zellmer, S.D. (Argonne National Lab., IL (United States)); Rastorfer, J.R. (Chicago State Univ., IL (United States). Dept. of Biological Sciences ANL/CSU Cooperative Herbarium, Chicago, IL (United States)); Van Dyke, G.D. (Trinity Christian Coll., Palos Heights, IL (United States). Dept. of Biology)
Implementation of recent federal and state regulations promulgated to protect wetlands makes information on effects of gas pipeline rights-of-way (ROWs) in wetlands essential to the gas pipeline industry. This study is designed to record vegetational changes induced by the construction of a large-diameter gas pipeline through deciduous forested wetlands. Two second-growth forested wetland sites mapped as Lenawee soils, one mature and one subjected to recent selective logging, were selected in Midland County, Michigan. Changes in the adjacent forest and successional development on the ROW are being documented. Cover-class estimates are being made for understory and ROW plant species using 1 {times}1-m quadrats. Counts are also being made for all woody species with stems < 2 cm in diameter at breast height (dbh) in the same plots used for cover-class estimates. Individual stem diameters and species counts are being recorded for all woody understory and overstory plants with stems {ge}2 cm dbh in 10 {times} 10-m plots. Although analyses of the data have not been completed, preliminary analyses indicate that some destruction of vegetation at the ROW forest edge may have been avoidable during pipeline construction. Rapid regrowth of many native wetland plant species on the ROW occurred because remnants of native vegetation and soil-bearing propagules of existing species survived on the ROW after pipeline construction and seeding operations. 91 refs., 11 figs., 3 tabs.
Enhancing phosphorus removal in constructed wetlands with ochre from mine drainage treatment.
Heal, K V; Dobbie, K E; Bozika, E; McHaffie, H; Simpson, A E; Smith, K A
No single end-use has yet been identified that is capable of consuming the projected production of ochre (mainly iron (III) oxides) from mine drainage treatment. However, the high sorption capacity of ochre for phosphorus (up to 26 mg kg(-1)) means that it could be used in constructed wetlands to enhance phosphorus removal. Laboratory batch experiments showed that coarse-grained ochre removes 90% of all phosphorus forms from sewage effluent after 15 minutes of shaking. From a larger-scale experiment, it is estimated that constructed wetlands with an ochre substrate should remove phosphorus from sewage effluent for up to 200-300 years. The suitability of ochre for phosphorus removal is being investigated at the field scale in a wastewater constructed wetland (175 m2 area) in Berwickshire, UK. The hydraulic and treatment performance of the wetland were monitored for 15 months prior to installation at the inlet in November 2003 of a tank containing approximately 1200 kg ochre. Results so far show that improved hydraulic design is required for ochre to increase the mean phosphorus removal efficiency of the system (27 +/- 28%), but potentially toxic metals (Al, Cd, Cr, Cu, Fe, Ni, Pb, Zn) have not been released from the ochre into the wetland outflow.
Nitrogen removal on recycling water process of wastewater treatment plant effluent using subsurface horizontal wetland with continuous feed
Tazkiaturrizki, T.; Soewondo, P.; Handajani, M.
Recycling water is a generic term for water reclamation and reuse to solve the scarcity of water. Constructed wetlands have been recognized as providing many benefits for wastewater treatment including water supply and control by recycling water. This research aims to find the best condition to significantly remove nitrogen using constructed wetland for recycling water of Bojongsoang Waste Water Treatment Plan (WWTP) effluent. Using media of soil, sand, gravel, and vegetation (Typha latifolia and Scirpus grossus) with an aeration system, BOD and COD parameters have been remarkably reduced. On the contrary, the removal efficiency for nitrogen is only between 50-60%. Modifications were then conducted by three step of treatment, i.e., Step I is to remove BOD/COD using Typha latifolia with an aeration system, Step II is todecrease nitrogen using Scirpus grossus with/without aeration, and Step III isto complete the nitrogen removal with denitrification process by Glycine max without aeration. Results of the research show that the nitrogen removal has been successfully increased to a high efficiency between 80-99%. The combination of aeration system and vegetation greatly affects the nitrogen removal. The vegetation acts as the organic nitrogen consumer (plant uptake) for amino acids, nitrate, and ammonium as nutrition, as well as theoxygen supplier to the roots so that aerobic microsites are formed for ammonification microorganisms.
Vertical flow constructed wetlands: kinetics of nutrient and organic matter removal.
Pérez, M M; Hernández, J M; Bossens, J; Jiménez, T; Rosa, E; Tack, F
The kinetics of organic matter and nutrient removal in a pilot vertical subsurface wetland with red ferralitic soil as substrate were evaluated. The wetland (20 m(2)) was planted with Cyperus alternifolius. The domestic wastewater that was treated in the wetland had undergone a primary treatment consisting of a septic moat and a buffer tank. From the sixth week of operation, the performance of the wetland stabilized, and a significant reduction in pollutant concentration of the effluent wastewater was obtained. Also a significant increase of dissolved oxygen (5 mg/l) was obtained. The organic matter removal efficiency was greater than 85% and the nutrient removal efficiency was greater than 75% in the vertical subsurface wetland. Nitrogen and biochemical oxygen demand (BOD) removal could be described by a first-order model. The kinetic constants were 3.64 and 3.27 d(-1) for BOD and for total nitrogen, respectively. Data on the removal of phosphorus were adapted to a second-order model. The kinetic constant was 0.96 (mg/l)(-1) d(-1). The results demonstrated the potential of vertical flow constructed wetlands to clean treated domestic wastewater before discharge into the environment.
Using constructed wetlands to treat subsurface drainage from intensively grazed dairy pastures in New Zealand.
Tanner, C C; Nguyen, M Long; Sukias, J P S
Performance data, during the start-up period, are presented for constructed wetlands treating subsurface drainage from dairy pastures in Waikato (rain-fed) and Northland (irrigated), North Island, New Zealand. The wetlands comprised an estimated 1 and 2% of the drained catchment areas, respectively. Nitrate concentrations were high in the drainage inflows at both sites (medians 10 g m(-3) at Waikato and 6.5 g m(-3) at Northland), but organic N was also an important form of N at Waikato (37% of TN). Comparison of wetland inflow and outflow nutrient concentrations showed overall nutrient reductions during passage through the wetlands for NO3-N (34 and 94% for medians, respectively), TN (56 and 33%, respectively), and DRP (80%, Northland only). Median NH4-N (both sites) and DRP (Waikato) concentrations showed apparent increases between the wetland inlets and outlets. However, a mass balance calculated for the 3 month preliminary monitoring periods showed substantial mass removal of DRP (80%) and all measured forms of N (NO3-N 78%, NH4-N 41%, Org-N 99.8% and TN 96%) in the Waikato wetland. Monitoring of these systems needs to be continued through a range of seasons and years to fully assess their long-term performance.
Effectiveness of a constructed wetland for treating alkaline bauxite residue leachate: a 1-year field study.
Higgins, Derek; Curtin, Teresa; Courtney, Ronan
Increasing volumes of bauxite residues and their associated leachates represent a significant environmental challenge to the alumina industry. Constructed wetlands have been proposed as a potential approach for leachate treatment, but there is limited data on field-scale applications. The research presented here provides preliminary evaluation of a purpose-built constructed wetland to buffer leachate from a bauxite residue disposal site in Ireland. Data collected over a 1-year period demonstrated that the pH of bauxite residue leachates could be effectively reduced from ca. pH 10.3 to 8.1 but was influenced by influent variability and temporal changes. The wetland was also effective in decreasing elemental loading, and sequential extractions suggested that the bulk of the sediment-bound metal inventory was in hard-to-leach phases. Elemental analysis of Phragmites australis showed that although vegetation displayed seasonal variation, no trace elements were at concentrations of concern.
Inferring energy sources in constructed wetlands through stable isotope analysis of microbial biofilms
Jurkowski, K.; Ciborowski, J. [Windsor Univ., ON (Canada); Daly, C. [Suncor Energy, Fort McMurray, AB (Canada)
This study presented a novel method of sequestering the microbial biofilm in constructed wetland ecosystems. Artificial substrates were fixed within 8 wetlands differing in age and construction materials over a 2 year period at oil sands lease sites in northeastern Alberta. Autotrophic and heterotrophic biofilm samples were collected from both the subsurface and epibenthic zones of the pipe surfaces of each submerged substrate assembly. A mixing model of d13C, d15N and d34S isotopic signatures was used to assess the contribution of 4 potential nutrient sources of the biofilm. Samples included dominant living and senescent emergent as well as submergent macrophytes, particulate organic matter, dissolved organic carbon, and invertebrates. The samples were collected to compare the biofilm signatures of each wetland in relation to the heterotrophic processes caused by the assimilation of oil sands-derived hydrocarbons and autochthonous detrital pools.
Jurkowski, K.; Ciborowski, J.; Daly, C.
Aquatic macrophytes can be used for wastewater polishing but not for purification in constructed wetlands
Tang, Yingying; Harpenslager, Sarah F.; van Kempen, Monique M. L.; Verbaarschot, Evi J. H.; Loeffen, Laury M. J. M.; Roelofs, Jan G. M.; Smolders, Alfons J. P.; Lamers, Leon P. M.
The sequestration of nutrients from surface waters by aquatic macrophytes and sediments provides an important service to both natural and constructed wetlands. While emergent species take up nutrients from the sediment, submerged and floating macrophytes filter nutrients directly from the surface water, which may be more efficient in constructed wetlands. It remains unclear, however, whether their efficiency is sufficient for wastewater purification and how plant species and nutrient loading affects nutrient distribution over plants, water and sediment. We therefore determined nutrient removal efficiencies of different vegetation (Azolla filiculoides, Ceratophyllum demersum and Myriophyllum spicatum) and sediment types (clay, peaty clay and peat) at three nutrient input rates, in a full factorial, outdoor mesocosm experiment. At low loading (0.43 mg P m-2 d-1), plant uptake was the main pathway (100 %) for phosphorus (P) removal, while sediments showed a net P release. A. filiculoides and M. spicatum showed the highest biomass production and could be harvested regularly for nutrient recycling, whereas C. demersum was outcompeted by spontaneously developing macrophytes and algae. Higher nutrient loading only stimulated A. filiculoides growth. At higher rates ( ≥ 21.4 mg P m-2 d-1), 50-90 % of added P ended up in sediments, with peat sediments becoming more easily saturated. For nitrogen (N), 45-90 % was either taken up by the sediment or lost to the atmosphere at loadings ≥ 62 mg N m-2 d-1. This shows that aquatic macrophytes can indeed function as an efficient nutrient filter but only for low loading rates (polishing) and not for high rates (purification). The outcome of this controlled study not only contributes to our understanding of nutrient dynamics in constructed wetlands but also shows the differential effects of wetland sediment types and plant species. Furthermore, the acquired knowledge may benefit the application of macrophyte harvesting to remove
AVALIAÇÃO DAS CONDIÇÕES HIDRODINÂMICAS DE WETLANDS DE ESCOAMENTO HORIZONTAL SUBSUPERFICIAL (UNIDADES PLANTADA E NÃO PLANTADA)
André Cordeiro De Paoli; Marcos von Sperling
Este trabalho teve o objetivo de avaliar o comportamento hidrodinâmico de duas wetlands construídas (WC) de escoamento horizontal subsuperficial e analisar comparativamente os respectivos parâmetros hidrodinâmicos gerados em cada sistema. No intuito de entender esse comportamento, foi realizado um teste simultâneo com elemento traçador (82Br) nas duas wetlands, uma plantada (WP) e outra não plantada (WNP), recebendo efluente sanitário de reator UASB (equivalente populacional de 50 habitantes...
On-site wastewater treatment using subsurface flow constructed wetlands in Ireland.
Gill, Laurence W; O'Luanaigh, Niall; Johnston, Paul M
The results from an Irish EPA-funded project on the effectiveness of using constructed wetlands for treating wastewater from single households is presented, which has contributed to the design guidelines included in the new EPA Code of Practice. Three subsurface flow gravel-filled wetlands were constructed on separate sites--one to provide secondary treatment and the other two to provide tertiary treatment stages for the domestic effluent. A comprehensive analysis over three years was then conducted to provide a robust characterization of the internal dynamics of the systems, particularly with respect to N and P removal as well as evaluating the temporal water balance across the different seasons. The removal of Total N was only 29% and 30% in the secondary and tertiary treatment wetlands, respectively; particularly disappointing for the tertiary treatment process, which was receiving nitrified effluent. Studies on the (15)N stable isotope confirmed that 35% of the ammonium from the septic tank was passing straight through the process without taking part in any biogeochemical processes. However, influent N in the wetlands was shown to be biologically assimilated into organic nitrogen and then released again as soluble ammonium--so-called nitrogen "spiraling." Removal of Total P in the wetlands averaged from 28% to 45% with higher P removals measured during summer periods, although the effluent concentrations were still found to be high (> 5 mg/l on average). The phosphorus in the plant material was also analysed revealing that the annual above-ground stem matter only accounted for 1.3% to 8.4% of the annual total P-load in the wetlands. Finally, the water balance analyses showed that the mean flow discharging from both the secondary and tertiary treatment wetlands was slightly greater than the mean flow to the reed bed over the trial period, with rainfall acting to increase flows by 13% and 5%, respectively, on average in winter while just about balancing
Multiyear nutrient removal performance of three constructed wetlands intercepting tile drain flows from grazed pastures.
Tanner, Chris C; Sukias, James P S
Subsurface tile drain flows can be a major s ource of nurient loss from agricultural landscapes. This study quantifies flows and nitrogen and phosphorus yields from tile drains at three intensively grazed dairy pasture sites over 3- to 5-yr periods and evaluates the capacity of constructed wetlands occupying 0.66 to 1.6% of the drained catchments too reduce nutrient loads. Continuous flow records are combined with automated flow-proportional sampling of nutrient concentrations to calculate tile drain nutrient yields and wetland mass removal rates. Annual drainage water yields rangedfrom 193 to 564 mm (16-51% of rainfall) at two rain-fed sites and from 827 to 853 mm (43-51% of rainfall + irrigation) at an irrigated site. Annually, the tile drains exported 14 to 109 kg ha(-1) of total N (TN), of which 58 to 90% was nitrate-N. Constructed wetlands intercepting these flows removed 30 to 369 gTN m(-2) (7-63%) of influent loadings annually. Seasonal percentage nitrate-N and TN removal were negatively associated with wetland N mass loadings. Wetland P removal was poor in all wetlands, with 12 to 115% more total P exported annually overall than received. Annually, the tile drains exported 0.12 to 1.38 kg ha of total P, of which 15 to 93% was dissolved reactive P. Additional measures are required to reduce these losses or provide supplementary P removal. Wetland N removal performance could be improved by modifying drainage systems to release flows more gradually and improving irrigation practices to reduce drainage losses.
Bacterial community dynamics in surface flow constructed wetlands for the treatment of swine waste.
Ibekwe, A M; Ma, J; Murinda, Shelton; Reddy, G B
Constructed wetlands are generally used for the removal of waste from contaminated water. In the swine production system, wastes are traditionally flushed into an anaerobic lagoon which is then sprayed on agricultural fields. However, continuous spraying of lagoon wastewater on fields can lead to high N and P accumulations in soil or lead to runoff which may contaminate surface or ground water with pathogens and nutrients. In this study, continuous marsh constructed wetland was used for the removal of contaminants from swine waste. Using pyrosequencing, we assessed bacterial composition within the wetland using principal coordinate analysis (PCoA) which showed that bacterial composition from manure influent and lagoon water were significantly different (P=0.001) from the storage pond to the final effluent. Canonical correspondence analysis (CCA) showed that different bacterial populations were significantly impacted by ammonium--NH4 (P=0.035), phosphate--PO4(3-) (P=0.010), chemical oxygen demand--COD (P=0.0165), total solids--TS (P=0.030), and dissolved solids--DS (P=0.030) removal, with 54% of the removal rate explained by NH4+PO4(3-) according to a partial CCA. Our results showed that different bacterial groups were responsible for the composition of different wetland nutrients and decomposition process. This may be the major reason why most wetlands are very efficient in waste decomposition. Published by Elsevier B.V.
Assessment of in situ biodegradation of monochlorobenzene in contaminated groundwater treated in a constructed wetland
Braeckevelt, Mareike; Rokadia, Hemal; Imfeld, Gwenael; Stelzer, Nicole; Paschke, Heidrun; Kuschk, Peter; Kaestner, Matthias; Richnow, Hans-H.; Weber, Stefanie
The degradation of monochlorobenzene (MCB) was assessed in a constructed wetland treating MCB contaminated groundwater using a detailed geochemical characterisation, stable isotope composition analysis and in situ microcosm experiments. A correlation between ferrous iron mobilisation, decreasing MCB concentration and enrichment in carbon isotope composition was visible at increasing distance from the inflow point, indicating biodegradation of MCB in the wetland. Additionally, in situ microcosm systems loaded with 13 C-labelled MCB were deployed for the first time in sediments to investigate the biotransformation of MCB. Incorporation of 13 C-labelled carbon derived from the MCB into bacterial fatty acids substantiated in situ degradation of MCB. The detection of 13 C-labelled benzene indicated reductive dehalogenation of MCB. This integrated approach indicated the natural attenuation of the MCB in a wetland system. Further investigations are required to document and optimise the in situ biodegradation of MCB in constructed and natural wetland systems treating contaminated groundwater. - An integrated approach including isotope composition analysis and in situ microcosm experiments provided evidences for in situ biodegradation of MCB in a wetland system
Braeckevelt, Mareike [Departments of Bioremediation, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany); Rokadia, Hemal [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany); Imfeld, Gwenael [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany)]. E-mail: gwenael.imfeld@ufz.de; Stelzer, Nicole [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany); Paschke, Heidrun [Department of Analytical Chemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany); Kuschk, Peter [Departments of Bioremediation, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany); Kaestner, Matthias [Departments of Bioremediation, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany); Richnow, Hans-H. [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany); Weber, Stefanie [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig D-04318, Saxonia (Germany)
The degradation of monochlorobenzene (MCB) was assessed in a constructed wetland treating MCB contaminated groundwater using a detailed geochemical characterisation, stable isotope composition analysis and in situ microcosm experiments. A correlation between ferrous iron mobilisation, decreasing MCB concentration and enrichment in carbon isotope composition was visible at increasing distance from the inflow point, indicating biodegradation of MCB in the wetland. Additionally, in situ microcosm systems loaded with {sup 13}C-labelled MCB were deployed for the first time in sediments to investigate the biotransformation of MCB. Incorporation of {sup 13}C-labelled carbon derived from the MCB into bacterial fatty acids substantiated in situ degradation of MCB. The detection of {sup 13}C-labelled benzene indicated reductive dehalogenation of MCB. This integrated approach indicated the natural attenuation of the MCB in a wetland system. Further investigations are required to document and optimise the in situ biodegradation of MCB in constructed and natural wetland systems treating contaminated groundwater. - An integrated approach including isotope composition analysis and in situ microcosm experiments provided evidences for in situ biodegradation of MCB in a wetland system.
Water reduction by constructed wetlands treating waste landfill leachate in a tropical region.
Ogata, Yuka; Ishigaki, Tomonori; Ebie, Yoshitaka; Sutthasil, Noppharit; Chiemchaisri, Chart; Yamada, Masato
One of the key challenges in landfill leachate management is the prevention of environmental pollution by the overflow of untreated leachate. To evaluate the feasibility of constructed wetlands (CWs) for the treatment of waste landfill leachate in tropical regions, water reduction and pollutant removal by a CW subjected to different flow patterns (i.e., horizontal subsurface flow (HSSF) and free water surface (FWS)) were examined in both rainy and dry seasons in Thailand. A pilot-scale CW planted with cattail was installed at a landfill site in Thailand. With HSSF, the CW substantially removed pollutants from the landfill leachate without the need to harvest plants, whereas with FWS, it only slightly removed pollutants. Under both flow patterns, the CW significantly reduced the leachate volume to a greater extent than surface evaporation, which is regarded as an effect of the storage pond. Additionally, water reduction occurred regardless of season and precipitation, within the range 0-9 mm d(-1). In the case of low feeding frequency, water reduction by the CW with HSSF was lower than that with FWS. However, high feeding frequency improved water reduction by the CW with HSSF and resulted in a similar reduction to that observed with FWS, which exhibited maximum evapotranspiration. In terms of water reduction, with both HSSF in conjunction with high frequency feeding and FWS, the CW provided a high degree of evapotranspiration. However, pollutant removal efficiencies with HSSF were higher than for FWS. The present study suggested that CWs with HSSF and high frequency feeding could be useful for the prevention of uncontrollable dispersion of polluted leachate in the tropical climate zone. Copyright © 2015 Elsevier Ltd. All rights reserved.
Performance of surface and subsurface flow constructed wetlands treating eutrophic waters.
Hernández-Crespo, C; Gargallo, S; Benedito-Durá, V; Nácher-Rodríguez, Beatriz; Rodrigo-Alacreu, M A; Martín, M
Three medium size constructed wetlands (CWs) with a total surface of 90ha are working since 2009 in the Albufera de Valencia Natural Park (Spain). Two of them are fed with eutrophic waters from l'Albufera Lake. Their objectives are both reduce the phytoplankton biomass and increase the biodiversity; consequently, improved water quality is returned to the lake. A "science based governance" of these CWs is ongoing inside the LIFE+12 Albufera Project to demonstrate the environmental benefits of these features. In this paper, results and relationships among hydraulic operation, physicochemical variables and plankton in two different CWs typologies, five free water surface CW (FWSCW) and one horizontal subsurface flow CW (HSSFCW), were analysed showing that CWs were capable of improving the water quality and biodiversity but showing clear differences depending on the CW type. The CWs worked under different hydraulic load rates (HLR) from <0.12 to 54.75myr -1 . Inflow water quality was typical from eutrophic waters with mean values of chlorophyll a (Chl a) about 22-90μgChlal -1 and mean total phosphorus (TP) between 0.122 and 0.337mgl -1 . The main conclusion is that HSSFCW was much more efficient than FWSCW in the removal of organic matter, suspended solids and nutrients. The biological role of several shallow lagoons located at the end of the CWs has also been evaluated, showing that they contribute to increase the zooplankton biomass, a key factor to control the phytoplankton blooms. Copyright © 2017 Elsevier B.V. All rights reserved.
Phosphorus retention in surface-flow constructed wetlands targeting agricultural drainage water
Dantas Mendes, Lipe Renato; Tonderski, Karin; Iversen, Bo Vangsø
Surface-flow constructed wetlands (CWs) are potential cost-efficient solutions to mitigate phosphorus (P) loads from agricultural areas to surface waters. Hydraulic and phosphorus loading rates (HLR and PLR) are critical parameters that regulate P retention in these systems. The present study aim...
Simulating phosphorus removal from a vertical-flow constructed wetland grown with C alternifolius species
Ying Ouyang; Lihua Cui; Gary Feng; John Read
Vertical flow constructed wetland (VFCW) is a promising technique for removal of excess nutrients and certain pollutants from wastewaters. The aim of this study was to develop a STELLA (structural thinking, experiential learning laboratory with animation) model for estimating phosphorus (P) removal in an artificial VFCW (i.e., a substrate column with six zones) grown...
Lessons learned from over two decades of constructed wetland : use for urban stormwater in the Netherlands
Boogaard, Floris; Vorenhout, Michel; Akkerman, Olof; de Lima, Rui; Blom, Johan
Constructed wetlands are one type of Sustainable Urban Drainage System (SUDS) that have been used for decades in The Netherlands. They provide stormwater conveyance and improve stormwater quality. European regulations for water quality dictate lower and lower concentrations for an array of dissolved
Suspended particle and pathogen peak discharge buffering by a surface-flow constructed wetland
Mulling, B.T.M.; van den Boomen, R.M.; van der Geest, H.G.; Kappelhof, J.W.N.M.; Admiraal, W.
Constructed wetlands (CWs) have been shown to improve the water quality of treated wastewater. The capacity of CWs to reduce nutrients, pathogens and organic matter and restore oxygen regime under normal operating conditions cannot be extrapolated to periods of incidental peak discharges. The
Greenhouse gas emissions from a constructed wetland - Plants as important sources of carbon
Picek, T.; Čížková, Hana; Dušek, J.
Ro�. 31, - (2007), s. 98-106 ISSN 0925-8574 R&D Projects: GA ČR GA526/06/0276 Institutional research plan: CEZ:AV0Z60870520 Keywords : Constructed wetland * Carbon dioxine * Methane * Nitrous oxide * Ges emissions Subject RIV: DJ - Water Pollution ; Quality Impact factor: 2.175, year: 2007
A comparison of charcoal- and slag-based constructed wetlands for ...
Subsurface-flow constructed wetlands (CW) with charcoal- or slag-based bed matrices were investigated for their potential use in remediating acid mine drainage (AMD). A CW is effectively a reactor in which some components of the wastewater are broken down by the organisms occurring within the CW, whilst others may ...
Effects of constructed wetland design on ibuprofen removal – A mesocosm scale study
Zhang, Liang; Lyu, Tao; Zhang, Yang
This study aimed to investigate the effects of constructed wetland design (unsaturated, saturated and aerated saturated) and plant species (Juncus, Typha, Berula, Phragmites and Iris) on the mass removal and removal kinetics of the pharmaceutical ibuprofen. Planted systems had higher ibuprofen...
Chlorobenzene removal efficiencies and removal processes in a pilot-scale constructed wetland treating contaminated groundwater
Braeckevelt, M.; Reiche, N.; Trapp, Stefan
Low-chlorinated benzenes (CBs) are widespread groundwater contaminants and often threaten to contaminate surface waters. Constructed wetlands (CWs) in river floodplains are a promising technology for protecting sensitive surface water bodies from the impact of CBs. The efficiency and seasonal var...
Removal efficiency of pharmaceuticals in a full scale constructed wetland in East Ukraine
Vystavna, Yuliya; Frková, Zuzana; Marchand, L.; Vergeles, Y.; Stolberg, F.
Ro�. 108, NOV (2017), s. 50-58 ISSN 0925-8574 Institutional support: RVO:60077344 Keywords : emerging pollutants * constructed wetland * wastewater treatment * Ukraine * pocis Subject RIV: DJ - Water Pollution ; Quality OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 2.914, year: 2016
The Revival of a Failed Constructed Wetland Treating of a High Fe Load AMD
A.D. Karathanasis; C.D. Barton
Acid mine drainage (AMD) from abandoned mines has significantly impaired water quality in eastern Kentucky. A small surface flow wetland constructed in 1989 to reduce AMD effects and subsequently failed after six months of operation was renovated by incorporating anoxic limestone drains (ALDs) and anaerobic subsurface drains promoting vertical flow through successive...
Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosms
We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures such as nutrients only (N, P), pesticides only (atrazine, S-metolachlor, permethrin), and nutrients+pesticides on phytoplankton chlorophyll a, 48 h aqueous Hyalella azteca survival, and 10 d se...
Pollutant swapping: greenhouse gas emissions from wetland systems constructed to mitigate agricultural pollution
Freer, Adam; Quinton, John; Surridge, Ben; McNamara, Niall
Diffuse (non-point) water pollution from agricultural land continues to challenge water quality management, requiring the adoption of new land management practices. The use of constructed agricultural wetlands is one such practice, designed to trap multiple pollutants mobilised by rainfall prior to them reaching receiving water. Through capturing and storing pollutants in bottom sediments, it could be hypothesised that the abundance of nutrients stored in the anoxic conditions commonly found in these zones may lead to pollutant swapping. Under these circumstances, trapped material may undergo biogeochemical cycling to change chemical or physical form and thereby become more problematic or mobile within the environment. Thus, constructed agricultural wetlands designed to mitigate against one form of pollution may in fact offset the created benefits by 'swapping' this pollution into other forms and pathways, such as through release to the atmosphere. Pollutant swapping to the atmosphere has been noted in analogous wetland systems designed to treat municipal and industrial wastewaters, with significant fluxes of CO2, CH4 and N2O being recorded in some cases. However the small size, low level of engineering and variable nutrient/sediment inputs which are features of constructed agricultural wetlands, means that this knowledge is not directly transferable. Therefore, more information is required when assessing whether a wetland's potential to act as hotspot for pollution swapping outweighs its potential to act as a mitigation tool for surface water pollution. Here we present results from an on-going monitoring study at a trial agricultural wetland located in small a mixed-use catchment in Cumbria, UK. Estimates were made of CH4, CO2 and N2O flux from the wetland surface using adapted floating static chambers, which were then directly compared with fluxes from an undisturbed riparian zone. Results indicate that while greenhouse gas flux from the wetland may be
Constructing a Baseline Model of Alpine Wetlands of the Uinta Mountains, Utah, USA
Matyjasik, M.; Ford, R. L.; Bartholomew, L. M.; Welsh, S. B.; Hernandez, M.; Koerner, D.; Muir, M.
between wetland and non-wetland areas. On-going analyses of water-chemistry data will be used to identify discrete water sources and to characterize the degree of horizontal and vertical water mixing within the system, as well as to help identify the biochemical requirements of the different plant communities. Results indicate that the chemical composition of the main creek reflects the accumulative effect that the peaty flarks have on the creek as it passes through the wetland system, with pH overall decreasing from 7.3 to 7.0, dissolved oxygen decreasing from 9400 to 8400 micrograms per liter and total dissolved solids increasing from 9 mg/L to 13 mg/L. String ground water is characterized by relatively high pH (ranging from 6.0 to 7.1), high oxidizing-reducing potential (ORP) (ranging from 50 mV to 180 mV), high dissolved oxygen (from 2500 μg/L to 9600 μg /L) while flark ground water has relatively lower pH (5.6 to 6.8), low oxidizing reducing potential (ORP) (ranging from -66 mV to 150 mV), low dissolved oxygen (from 900 μg /L to 9000 μg /L).
A Preliminary Investigation of Wastewater Treatment Efficiency and Economic Cost of Subsurface Flow Oyster-Shell-Bedded Constructed Wetland Systems
Chia-Chuan Hsu
Full Text Available We conducted a preliminary investigation of wastewater treatment efficiency and economic cost of the oyster-shell-bedded constructed wetlands (CWs compared to the conventional gravel-bedded CW based on field monitoring data of water quality and numerical modeling. Four study subsurface (SSF CWs were built to receive wastewater from Taipei, Taiwan. Among these sites, two are vertical wetlands, filled with bagged- (VA and scattered- (VB oyster shells, and the other two horizontal wetlands were filled with scattered-oyster shells (HA and gravels (HB. The BOD, NO3−, DO and SS treatment efficiency of VA and VB were higher than HA and HB. However, VA was determined as the best option of CW design due to its highest cost-effectiveness in term of BOD removal (only 6.56 US$/kg as compared to VB, HA and HB (10.88–25.01 US$/kg. The results confirmed that oyster shells were an effective adsorption medium in CWs. Hydraulic design and arrangement of oyster shells could be important in determining their treatment efficiency and cost-effectiveness. A dynamic model was developed to simulate substance transmissions in different treatment processes in the CWS using AQUASIM 2.1 based on the water quality data. Feasible ranges of biomedical parameters involved were determined for characterizing the importance of different biochemical treatment processes in SSF CWs. Future work will involve extending the experimental period to confirm the treatment efficiency of the oyster-shell-bedded CW systems in long-term operation and provide more field data for the simulated model instead of the literature values.
Application of fluorescence spectroscopy for dissolved organic matter characterization in constructed wetlands
Sardana, A.; Aziz, T. N.; Cottrell, B. A.
In this presentation we will discuss our ongoing work to characterize the photochemical behavior of dissolved organic matter (DOM) from wastewater treated in constructed wetlands. We have used a suite of spectroscopic and chromatographic techniques to characterize the DOM and to quantify the potential production of reactive oxygenated species (ROS). In the present study, DOM was fractionated based on its hydrophobicity and both the natural water isolates and fractionated DOM were characterized using SUVA254, spectral slope ratios, excitation emission matrix fluorescence spectroscopy (EEMs) and proton nuclear magnetic resonance (1H NMR). Photodegradation of wetland DOM and the formation of the hydroxyl radical (*OH), singlet oxygen (1O2), and the triplet-excited state (3DOM*) was also determined to assess the reactivity of DOM. EEM spectra exhibited the four main fluorescence peaks that are characteristic of DOM: peak A humic-like DOM, Peak C (fulvic or chromophoric DOM), Peak M (marine-like DOM), and peak T (tryptophan or protein-like absorbance). Two additional observed peaks with shorter emission wavelengths (A' Ex/Em = 243/278 nm and T' Ex/Em = 272/319 nm) were attributed to the microbial DOM in wastewater effluent. The spectral slope ratios decreased from 1.46 at the wetland inlet to 0.89 at the wetland outlet. The protein-like Peak T fluorescence decreased from 50% at the wetland inlet to 6.7% at the Wetland 2 outlet. A negative correlation between the percent fluorescence of Peak T and Peaks A, C and M confirmed the transition from the spectrum of pure wastewater with a primarily protein-like signature to a spectrum characteristic of terrestrially derived DOM. This transition coincided with enhanced formation rates and steady state concentrations of photochemically produced reactive intermediates (PPRIs). Size Exclusion Chromatography demonstrated that the influent wastewater had a lower molecular weight as compared to downstream wetland locations
Effects of acidification on metal accumulation by aquatic plants and invertebrates. 1. Constructed wetlands
Albers, P.H.; Camardese, M.B.
The pH of lake water is often inversely correlated with concentrations of trace metals in the water column. Concentrations of Al, Cd, Ca, Cu, Fe, Hg, Pb, Mg, Mn, Ni, P, and Zn were compared in water, plants, and aquatic insects from three acidified (pH 5.0) and three nonacidified (pH 6.5) constructed wetlands. Concentrations of Zn in water and bur-reed (Sparganium americanum) were higher in acidified wetlands than in nonacidified wetlands. Floating nonrooted plants contained mean concentrations of Fe, Mg, and Mn that were higher than recommended maximum levels for poultry feed. The mean concentrations of all metals in insects were below recommended maximum levels for poultry feed and below levels that cause toxic effects in wild birds. Smaller than expected increases of metal concentrations in the water of acidified wetlands were probably due to limited mobilization of metals from the sediments and insignificant changes in sedimentation of aqueous metals. Calcium was lower in acidified than in nonacidified wetland water, but the Ca content of insects and bur-reed was not lower. Low concentrations of Ca in aquatic insects from both groups of wetlands indicate that calcium-rich crustaceans and mollusks are probably important to female waterfowl and their young during the spring, when invertebrates make up the majority of the diet. Although toxic effects from metal ingestion seem to be unlikely consequences of wetland acidification, the adverse effect of low pH on the occurrence of crustaceans and mollusks could threaten egg production and development of young.
Investigation of nitrogen transformations in a southern California constructed wastewater treatment wetland
Sartoris, J.J.; Thullen, J.S.; Barber, L.B.; Salas, D.E.
A 9.9-ha combined habitat and wastewater treatment demonstration wetland was constructed and planted in the summer of 1994, at Eastern Municipal Water District's (EMWD) Hemet/San Jacinto Regional Water Reclamation Facility (RWRF) in southern California. From January 1996 through September 1997, the marsh–pond–marsh wetland system was operated to polish an average of 3785 m3 d−1 (1×106 gal day−1) of secondary-treated effluent from the RWRF. Nitrogen removal was a major objective of this wetland treatment. Weekly inflow/outflow water quality monitoring of the wetland was supplemented with biannual, 45-station synoptic surveys within the system to determine internal distribution patterns of the nitrogen species (total ammonia, nitrite, nitrate, and organic nitrogen), total organic carbon (TOC), and ultraviolet absorbance at 254 nm (UV254). Synoptic surveys were carried out during May 22 and September 17, 1996, and May 6 and September 25, 1997 and the results were mapped using the ARC/INFO processing package and inverse distance weighted mathematical techniques. Distribution patterns of the various nitrogen species, TOC, and UV254 within the wetland indicate that the nitrogen dynamics of the system are influenced both by variations in treatment plant loading, and, increasingly, by the degree of coverage and maturity of the emergent vegetation.
Environmental monitoring and assessment of the water bodies of a pre-construction urban wetland.
Zuo, Shengpeng; Wan, Kun; Zhou, Shoubiao; Ye, Liangtao; Ma, Sumin
It is planned that the Dayanghan Wetland in China will be transformed into a national park but little is known about its current water quality and pollution status. Thus, we monitored the physical and chemical characteristics of the Dayanghan Wetland, which showed that the water quality was generally good. However, the chemical oxygen demand was more than double the reference value, which may be attributable to previous tillage for vegetable crops and other farmlands. In addition, nickel and chromium caused low-level pollution in the water bodies of the Dayanghan Wetland. The mean trophic level index and nutrient quality index were 39.1 and 2.69, respectively. Both indices suggest that the water bodies of the Dayanghan Wetland are in a mesotrophic state and that no eutrophication has occurred. The study would provide a precise report on the status of environmental quality of the water bodies of a typical pre-construction wetland for the administration and decision of the local government and the planning agent.
Distribution and turnover of carbon in natural and constructed wetlands in the Florida Everglades
Stern, J.; Wang, Y.; Gu, B.; Newman, J.
Stable and radiocarbon isotopic contents of dissolved organic C (DOC), dissolved inorganic C (DIC), particulate organic C (POC) and plants were used to examine the source and turnover rate of C in natural and constructed wetlands in the Florida Everglades. DOC concentrations decreased, with P concentrations, along a water quality gradient from the agriculturally impacted areas in the northern Everglades to the more pristine Everglades National Park. δ 13 C values of DOC in the area reflect contributions of both wetland vegetation and sugarcane from agriculture. Radiocarbon ages of DOC, POC and DIC in the Everglades ranged from 2.01 ka BP to '>modern'. The old 14 C ages of DOC and POC were found in impacted areas near the Everglades Agricultural Area (EAA) in the northern Everglades. In contrast, DOC and POC in pristine marsh areas had near modern or '>modern' 14 C ages. These data indicate that a major source of POC and DOC in impacted areas is the degradation of historic peat deposits in the EAA. In the pristine areas of the marsh, DOC represents a mix of modern and historic C sources, whereas POC comes from modern primary production as indicated by positive Δ 14 C values, suggesting that DOC is transported farther away from its source than POC. High Δ 14 C values of DIC indicate that dissolution of limestone bedrock is not a significant source of DIC in the Everglades wetlands. As a restored wetland moves towards its 'original' or 'natural' state, the 14 C signatures of DOC should approach that of modern atmosphere. In addition, measurements of concentration and C isotopic composition of DOC in two small constructed wetlands (i.e., test cells) indicate that these freshwater wetland systems contain a labile DOC pool with rapid turnover times of 26-39 days and that the test cells are overall net sinks of DOC
The role of constructed wetlands for biomass production within the water-soil-waste nexus.
Avellan, C T; Ardakanian, R; Gremillion, P
The use of constructed wetlands for water pollution control has a long standing tradition in urban, peri-urban, rural, agricultural and mining environments. The capacity of wetland plants to take up nutrients and to filter organic matter has been widely discussed and presented in diverse fora and published in hundreds of articles. In an ever increasingly complex global world, constructed wetlands not only play a role in providing safe sanitation in decentralized settings, shelter for biodiversity, and cleansing of polluted sites, in addition, they produce biomass that can be harvested and used for the production of fodder and fuel. The United Nations University Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES) was established in December 2012 in Dresden, Germany, to assess the trade-offs between and among resources when making sustainable decisions. Against the backdrop of the Water-Energy-Food Nexus, which was introduced as a critical element for the discussions on sustainability at Rio +20, the UNU was mandated to pay critical attention to the interconnections of the underlying resources, namely, water, soil and waste. Biomass for human consumption comes in the form of food for direct use, as fodder for livestock, and as semi-woody biomass for fuelling purposes, be it directly for heating and cooking or for the production of biogas and/or biofuel. Given the universal applicability of constructed wetlands in virtually all settings, from arid to tropical, from relatively high to low nutrient loads, and from a vast variety of pollutants, we postulate that the biomass produced in constructed wetlands can be used more extensively in order to enhance the multi-purpose use of these sites.
Impact of hydraulic and carbon loading rates of constructed wetlands on contaminants of emerging concern (CECs) removal
Sharif, Fariya; Westerhoff, Paul; Herckes, Pierre
Constructed wetlands remove trace organic contaminants via synergistic processes involving plant biomass that include hydrolysis, volatilization, sorption, biodegradation, and photolysis. Wetland design conditions, such as hydraulic loading rates (HLRs) and carbon loading rates (CLRs), influence these processes. Contaminant of emerging concern (CEC) removal by wetland plants was investigated at varying HLRs and CLRs. Rate constants and parameters obtained from batch-scale studies were used in a mechanistic model to evaluate the effect of these two loading rates on CEC removal. CLR significantly influenced CEC removal when wetlands were operated at HLR >5 cm/d. High values of CLR increased removal of estradiol and carbamazepine but lowered that of testosterone and atrazine. Without increasing the cumulative HLR, operating two wetlands in series with varying CLRs could be a way to improve CEC removal. -- Highlights: • A fate-predictive model was developed to evaluate the effect of loading rates on CEC removal in constructed wetlands. • Carbon loading rates (CLRs) can influence CEC removal when wetlands are operated at higher hydraulic loading rates (HLRs). • The effect of CLRs varies among CECs with different physico-chemical properties. • Combination of wetlands with different CLRs can optimize CEC removal without changing the net HLR. -- This article evaluates the effect of design loading rates on contaminant of emerging concern (CEC) removal in constructed wetlands
Constructing a multi-sided business model for a smart horizontal IoT service platform
Berkers, F.; Roelands, M.; Bomhof, F.; Bachet, T.; Van Rijn, M.; Koers, W.
In order to realize a viable business ecosystem in the Internet of Things (IoT), we investigated how a smart horizontal IoT service platform can bring value and economies of scale to all required ecosystem stakeholders. By means of an example application domain case, this paper constructs a
Effects of Misgurnus anguillicaudatus and Cipangopaludina cathayensis on Pollutant Removal and Microbial Community in Constructed Wetlands
Pengfei Li
Full Text Available Aquatic animals play an important role in the energy flow and matter cycling in the wetland ecosystem. However, little is known about their effects on pollutant removal performance and microbial community in constructed wetlands. This work presents an initial attempt to investigate the effects of Misgurnus anguillicaudatus (loach and Cipangopaludina cathayensis (snail on nutrient removal performance and microbial community of constructed wetlands (CWs. Compared with a control group, CW microcosms with aquatic animals exhibited better pollutant removal performance. The removal efficiencies of total phosphorus (TP in the loach group were 13.1% higher than in the control group, and snails increased the ammonium removal most effectively. Moreover, the concentration of total organic carbon (TOC and TP in sediment significantly reduced with the addition of loaches and snails (p < 0.05, whereas the concentration of total nitrogen (TN showed an obvious increase with the addition of loaches. High-throughput sequencing showed a microbial community structure change. Loaches and snails in wetlands changed the microbial diversity, especially in the Proteobacteria and denitrifying community. Results suggested that benthic aquatic animals might play an important role in CW ecosystems.
ASSESSING THE EFFECT OF ANTIBIOTICS ON THE RESISTANCE OF RESIDENT MICROBES IN WETLANDS CONSTRUCTED FOR WASTEWATER TREATMENT
The use of constructed wetlands as a cost effective and environmentally friendly option for wastewater treatment is becoming more prevalent. These systems are championed as combining many of the benefits of tertiary treatment while also providing high quality wetland habitat as...
Finding the harvesting frequency to maximize nutrient removal in a constructed wetland dominated by submerged aquatic plants
Verhofstad, M.J.J.M.; Poelen, M.D.M.; Van Kempen, M.M.L.; Bakker, E.S.; Smolders, A.J.P.
Water quality is still poor in many freshwater ecosystems around the world as a result of anthropogenic nutrient loading. Constructed wetlands can be used to remove excess nutrients. In these wetlands, helophytes or free floating aquatic plants are traditionally used to absorb the nutrients. The
A constructed treatment wetland for pulp and paper mill wastewater: performance, processes and implications for the Nzoia River, Kenya
Abira, M.A.
The doctoral research study conducted in Kenya gives the first insight into the performance of a constructed treatment wetland receiving pulp and paper mill wastewater in the tropics. The wetland effectively removed organic matter, suspended solids, phenols and nutrients. BOD and phenols reduction
The phytoremediation ability of a polyculture constructed wetland to treat boron from mine effluent
Türker, Onur Can; Böcük, Harun; Yakar, Anıl
Highlights: ► We assessed the phytoremediation ability of a polyculture constructed wetland (PCW) to treat boron (B) from mine effluent. ► B in mine effluent decreased from 187 mg l −1 to 123 mg l −1 (32% removal rate) through the PCW. ► Estimated methane production, energy yields and electrical energy yields of the PCW increased with biomass production. ► Cattails accumulated more than 250 mg kg −1 B and common reed accumulated 38 mg kg −1 B at the end of the experiment. -- Abstract: This study focuses on describing the ability of a small-scale, subsurface-flow-polyculture-constructed wetland (PCW) to treat boron (B) mine effluent from the world's largest borax mine (Kırka, Turkey) under field conditions. This application is among the first effluent treatment methods of this type in both Turkey and the world. This study represents an important resource on how subsurface-flow-constructed wetlands could be used to treat B mine effluents in the field conditions. To this end, an experimental wetland was vegetated with common reed (Phragmites australis) and cattails (Typha latifolia), and mine effluent was moved through the wetland. The results of the present study show that B concentrations of the mine effluent decreased from 187 to 123 mg l −1 (32% removal rate) on average. The T. latifolia individuals absorbed a total of 250 mg kg −1 whereas P. australis in the PCW absorbed a total of 38 mg kg −1 B during the research period
Türker, Onur Can [Faculty of Science and Letters, Department of Biology, Aksaray University, Aksaray (Turkey); Böcük, Harun, E-mail: hbocuk@anadolu.edu.tr [Faculty of Science, Department of Biology, Anadolu University, Eskişehir (Turkey); Yakar, Anıl [Faculty of Science, Department of Biology, Anadolu University, Eskişehir (Turkey)
Highlights: ► We assessed the phytoremediation ability of a polyculture constructed wetland (PCW) to treat boron (B) from mine effluent. ► B in mine effluent decreased from 187 mg l{sup −1} to 123 mg l{sup −1} (32% removal rate) through the PCW. ► Estimated methane production, energy yields and electrical energy yields of the PCW increased with biomass production. ► Cattails accumulated more than 250 mg kg{sup −1} B and common reed accumulated 38 mg kg{sup −1} B at the end of the experiment. -- Abstract: This study focuses on describing the ability of a small-scale, subsurface-flow-polyculture-constructed wetland (PCW) to treat boron (B) mine effluent from the world's largest borax mine (Kırka, Turkey) under field conditions. This application is among the first effluent treatment methods of this type in both Turkey and the world. This study represents an important resource on how subsurface-flow-constructed wetlands could be used to treat B mine effluents in the field conditions. To this end, an experimental wetland was vegetated with common reed (Phragmites australis) and cattails (Typha latifolia), and mine effluent was moved through the wetland. The results of the present study show that B concentrations of the mine effluent decreased from 187 to 123 mg l{sup −1} (32% removal rate) on average. The T. latifolia individuals absorbed a total of 250 mg kg{sup −1} whereas P. australis in the PCW absorbed a total of 38 mg kg{sup −1} B during the research period.
Distribution of Organic Carbon in the Sediments of Xinxue River and the Xinxue River Constructed Wetland, China.
Cao, Qingqing; Wang, Renqing; Zhang, Haijie; Ge, Xiuli; Liu, Jian
Wetland ecosystems are represented as a significant reservoir of organic carbon and play an important role in mitigating the greenhouse effect. In order to compare the compositions and distribution of organic carbon in constructed and natural river wetlands, sediments from the Xinxue River Constructed Wetland and the Xinxue River, China, were sampled at two depths (0-15 cm and 15-25 cm) in both upstream and downstream locations. Three types of organic carbon were determined: light fraction organic carbon, heavy fraction organic carbon, and dissolved organic carbon. The results show that variations in light fraction organic carbon are significantly larger between upstream and downstream locations than they are between the two wetland types; however, the opposite trend is observed for the dissolved organic carbon. There are no significant differences in the distribution of heavy fraction organic carbon between the discrete variables (e.g., between the two depths, the two locations, or the two wetland types). However, there are significant cross-variable differences; for example, the distribution patterns of heavy fraction organic carbon between wetland types and depths, and between wetland types and locations. Correlation analysis reveals that light fraction organic carbon is positively associated with light fraction nitrogen in both wetlands, while heavy fraction organic carbon is associated with both heavy fraction nitrogen and the moisture content in the constructed wetland. The results of this study demonstrate that the constructed wetland, which has a relatively low background value of heavy fraction organic carbon, is gradually accumulating organic carbon of different types, with the level of accumulation dependent on the balance between carbon accumulation and carbon decomposition. In contrast, the river wetland has relatively stable levels of organic carbon.
Candidate soil indicators for monitoring the progress of constructed wetlands toward a natural state: a statistical approach
Stapanian, Martin A.; Adams, Jean V.; Fennessy, M. Siobhan; Mack, John; Micacchion, Mick
A persistent question among ecologists and environmental managers is whether constructed wetlands are structurally or functionally equivalent to naturally occurring wetlands. We examined 19 variables collected from 10 constructed and nine natural emergent wetlands in Ohio, USA. Our primary objective was to identify candidate indicators of wetland class (natural or constructed), based on measurements of soil properties and an index of vegetation integrity, that can be used to track the progress of constructed wetlands toward a natural state. The method of nearest shrunken centroids was used to find a subset of variables that would serve as the best classifiers of wetland class, and error rate was calculated using a five-fold cross-validation procedure. The shrunken differences of percent total organic carbon (% TOC) and percent dry weight of the soil exhibited the greatest distances from the overall centroid. Classification based on these two variables yielded a misclassification rate of 11% based on cross-validation. Our results indicate that % TOC and percent dry weight can be used as candidate indicators of the status of emergent, constructed wetlands in Ohio and for assessing the performance of mitigation. The method of nearest shrunken centroids has excellent potential for further applications in ecology.
Environmental assessment for the A-01 outfall constructed wetlands project at the Savannah River Site
The Department of Energy (DOE) prepared this environmental assessment (EA) to analyze the potential environmental impacts associated with the proposed A-01 outfall constructed wetlands project at the Savannah River site (SRS), located near aiken, South Carolina. The proposed action would include the construction and operation of an artificial wetland to treat effluent from the A-01 outfall located in A Area at SRS. The proposed action would reduce the outfall effluent concentrations in order to meet future outfall limits before these go into effect on October 1, 1999. This document was prepared in compliance with the National Environmental Policy Act (NEPA) of 1969, as amended; the requirements of the Council on Environmental Quality Regulations for Implementing NEPA (40 CFR Parts 1500--1508); and the DOE Regulations for Implementing NEPA (10 CFR Part 1021)
Low methane flux from a constructed boreal wetland
Clark, M. G.; Humphreys, E.; Carey, S. K.
The Sandhill Fen Watershed project in northern Alberta, Canada, is a pilot study in reconstructing a mixed upland and lowland boreal plain ecosystem. The physical construction of the 50 ha area was completed in 2012 and revegetation programs, through planting and seeding, began that same year and continued into 2013. Since then, the vegetation has developed a substantial cover over the reclaimed soil and peat substrates used to cap the engineered topography constructed from mine tailings. To monitor the dynamics of carbon cycling processes in this novel ecosystem, near weekly gas chamber measurements of methane fluxes were carried out over 3 growing seasons. Soil moisture, temperature and ion flux measurements, using Plant Root Simulator probes, were also collected alongside the gas flux plots. In the 3rd season, a transect was established in the lowlands along a moisture gradient to collect continuous reduction-oxidation potential measurements along with these other variables. Overall, methane effluxes remained low relative to what is expected for rewetted organic substrates. However, there is a trend over time towards increasing methane gas emissions that coincides with increasing fluxes of reduced metal ions and decreasing fluxes of sulphate in the fully saturated substrates. The suppressed levels of methane fluxes are possibly due to naturally occurring high levels of sulphate in the donor materials used to cap the ecosystem construction.
Plant growth and microbial processes in a constructed wetland planted with Phalaris arundinacea
Edwards, K.R.; Čížková, Hana; Zemanová, K.; Šantrů�ková, H.
Ro�. 27, �. 2 (2006), s. 153-165 ISSN 0925-8574 R&D Projects: GA ČR(CZ) GA206/02/1036 Institutional research plan: CEZ:AV0Z60870520 Keywords : Constructed wetland * N mineralization * P mineralization * nutrient uptake * Phalaris arundinacea * non-structural carbohydrates * eutrophication Subject RIV: DJ - Water Pollution ; Quality Impact factor: 1.331, year: 2006
Skrzypiecbcef Katarzyna; Gajewskaad Magdalena H.
Constructed wetlands are characterized by specific conditions enabling simultaneous various physical and biochemical processes. This is the result of specific environment for the growth of microorganisms and hydrophytes (aquatic and semiaquatic plants) which are capable of living in aerobic, anaerobic and facultative anaerobic conditions. Their interaction contributes to the intensification of oxidation and reduction responsible for the removal and retention of pollutants. These processes are...
Drainage filters and constructed wetlands to mitigate site-specific nutrient losses
Kjærgaard, Charlotte; Hoffmann, Carl Christian; Iversen, Bo Vangsø
Despite substantial efforts, the leaching of nutrients from agricultural land is still a serious and costly environmental problem in Denmark and elsewhere. The quality goals of the European Water Framework Directive (WFD) for the aquatic environment require a substantial reduction of diffuse nutr...... drainage. The project studies different approaches of implementing the filter technologies including drainage well or drainage pipe filters as well as surface-flow and sub-surface flow constructed wetlands....
Subsurface flow constructed wetlands for the treatment of wastewater from different sources. Design and operation
Torrens Armengol, Antonina
The aim of the thesis is to examine the viability of the subsurface constructed wetlands for the treatment of wastewater derived from three different sources (treatment ponds, pig farms and car wash facilities), and to evaluate the influence of design (size, type and depth of media, presence of Phragmites australis) and operational parameters (hydraulic load, dosing and feeding modes) on treatment efficiency and hydraulic behavior. Several studies were done in the framework of different ...
Constructed Wetlands as a Mitigation Strategy to Reduce Pesticide Loads in Agricultural Tailwater
Budd, Robert L.
Pyrethroid and organophosphate pesticides have been found in numerous waterways throughout the United States. Monitoring studies within the San Diego Creek watershed in Orange County, California, confirmed that runoff from agricultural fields are a primary contributor to pesticide loads within these waterways. As a mitigation option for non-point pesticide pollution, constructed wetlands were investigated in this study to reduce pesticide loading in agricultural tailwaters. Multiple wetlan...
A Comparison of Modeling Approaches in Simulating Chlorinated Ethene Removal in a Constructed Wetland by a Microbial Consortia
Campbell, Jason
The purpose of this study is to compare different approaches to modeling the reductive dechlorination of chlorinated ethenes in the anaerobic region of an upward flow constructed wetland by microbial consortia...
Comparative assessment of managed aquifer recharge versus constructed wetlands in managing chemical and microbial risks during wastewater reuse: A review
Hamadeh, Ahmed F.; Sharma, Saroj K.; Amy, Gary L.
Constructed wetlands (CWs) and managed aquifer recharge (MAR) represent commonly used natural treatment systems for reclamation and reuse of wastewater. However, each of these technologies have some limitations with respect to removal of different
Intensified nitrogen and phosphorus removal in a novel electrolysis-integrated tidal flow constructed wetland system.
Ju, Xinxin; Wu, Shubiao; Zhang, Yansheng; Dong, Renjie
A novel electrolysis-integrated tidal flow constructed wetland (CW) system was developed in this study. The dynamics of intensified nitrogen and phosphorus removal and that of hydrogen sulphide control were evaluated. Ammonium removal of up to 80% was achieved with an inflow concentration of 60 mg/L in wetland systems with and without electrolysis integration. Effluent nitrate concentration decreased from 2 mg/L to less than 0.5 mg/L with the decrease in current intensity from 1.5 mA/cm(2) to 0.57 mA/cm(2) in the electrolysis-integrated wetland system, thus indicating that the current intensity of electrolysis plays an important role in nitrogen transformations. Phosphorus removal was significantly enhanced, exceeding 95% in the electrolysis-integrated CW system because of the in-situ formation of a ferric iron coagulant through the electro-dissolution of a sacrificial iron anode. Moreover, the electrolyzed wetland system effectively inhibits sulphide accumulation as a result of a sulphide precipitation coupled with ferrous-iron electro-dissolution and/or an inhibition of bacterial sulphate reduction under increased aerobic conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.
Water Purification Characteristic of the Actual Constructed Wetland with Carex dispalata in a Cold Area
Tsuji, Morio; Yamada, Kazuhiro; Hiratsuka, Akira; Tsukada, Hiroko
Carex dispalata, a native plant species applied in cold districts for water purification in constructed wetlands, has useful characteristics for landscape creation and maintenance. In this study, seasonal differences in purification ability were verified, along with comparison of frozen and non-frozen periods' performance. A wetland area was constructed using a "hydroponics method� and a "coir fiber based method�. Results show that the removal rates of BOD, SS, and Chl-a were high. On this constructed wetland reduces organic pollution, mainly phytoplankton, but the removal of nitrogen and phosphorus was insufficient. The respective mean values of influent and treated water during three years were 26.6 mg/L and 12.2 mg/L for BOD, and 27.9 mg/L and 7.5 mg/L for SS. The mean value of the BOD removal rate for the non-frozen period was 2.99 g/m2/d that for the frozen period was 1.86 g/m2/d. The removal rate followed the rise of the BOD load rate. The removal rate limits were about 4 g/m2/d during the frozen period and 15 g/m2/d during the non-frozen period. For operations, energy was unnecessary. The required working hours were about 20 h annually for all maintenance and management during operations.
Removal of chlorpyrifos insecticide in constructed wetlands with different plant species
Tamara D. de Souza
Full Text Available ABSTRACT The objective of this study was to evaluate the remediation of water containing the insecticide chlorpyrifos by using constructed wetlands (CW cultivated with Polygonum punctatum, Cynodon spp. and Mentha aquatica, operated under different hydraulic retention times: 24, 48, 96, 144 and 192 h. The system efficiency was based on reduction of the initial concentration of chlorpyrifos and toxicity of the contaminated water. The results showed that constructed wetlands are an excellent alternative for remediation of the insecticide chlorpyrifos in aqueous medium. It was observed that the average overall removal efficiency of the insecticide was 98.6%, and in the first hydraulic retention time, 24 h, chlorpyrifos was removed to levels below the detection limit in all CW. This result is mainly attributed to adsorption and microbial degradation. For the qualitative standard acute toxicity tests with Daphnia similis, for most samples there was a reduction in toxicity greater than 80%. It was reported that the ecotoxicological tests with the effluents of the constructed wetland are a good option as an indicator of the effectiveness of treatments and a promising alternative to complement the physical and chemical analyses.
Bacteriophage Technique for Assessing Viral Removal in Constructed Wetland and Detention Pond Systems
Z Yousefi, CM Davies, HJ Bavor
Full Text Available Constructed wetland and detention pond as a treatment system was applied for stormwater management in two adjacent areas in western Sydney. F-specific RNA and somatic coliphages were used as a model for assessing two systems for removal of viral pollution, fate, behavior and survival of viruses in the sediment. Water samples were collected weekly in sterile containers and sediment samples were collected three times using a box dredge sampler via a boat at the inlet, middle and outlet areas of the systems. F-specific RNA coliphages were enumerated using the double layer plaque assay (ISO 1995 with Salmonella typhimurium WG49 as a host. Survival test continued 28 d for each sub-sample. Viral removal in constructed wetland was more effective than the detention pond system. Survival of somatic coliphages in the inlet and middle of the systems was similar. Slope of declining for outlet of two systems was very slow and completely stable in whole of test duration. Constructed wetland may offer an attractive alternative to stormwater management for reducing the load of disease-causing viruses to the receiving waters.
Batch versus continuous feeding strategies for pharmaceutical removal by subsurface flow constructed wetland
Zhang Dongqing; Gersberg, Richard M.; Zhu, Junfei; Hua, Tao; Jinadasa, K.B.S.N.; Tan, Soon Keat
This study evaluated the effect of continuous and batch feeding on the removal of 8 pharmaceuticals (carbamazepine, naproxen, diclofenac, ibuprofen, caffeine, salicylic acid, ketoprofen and clofibric acid) from synthetic wastewater in mesocosm-scale constructed wetlands (CWs). Both loading modes were operated at hydraulic application rates of 5.6 cm day −1 and 2.8 cm day −1 . Except for carbamazepine, clofibric acid and naproxen, removal in CWs was significantly (p ow ) and removal efficiencies of pharmaceutical compounds in the CWs, showed that pharmaceutical removal efficiency was significantly (p ow value, but not with log K ow value. - Highlights: ► Batch feeding in mesocosm-scale constructed wetlands enhances pharmaceutical removal. ► K values for the 8 pharmaceuticals were in the range of 0.01–0.1 m day −1 . ► The pharmaceutical removal efficiency was inversely correlated with log D ow value. - Batch (drain and fill) feeding in mesocosm-scale constructed wetlands enhances pharmaceutical removal.
Investigations of subsurface flow constructed wetlands and associated geomaterial resources in the Akumal and Reforma regions, Quintana Roo, Mexico
Krekeler, Mark P. S.; Probst, Pete; Samsonov, Misha; Tselepis, Cynthia M.; Bates, William; Kearns, Lance E.; Maynard, J. Barry
Subsurface flow constructed wetlands in the village of Akumal, Quintana Roo, Mexico were surveyed to determine the general status of the wetland systems and provide baseline information for long term monitoring and further study. Twenty subsurface flow wetlands were surveyed and common problems observed in the systems were overloading, poor plant cover, odor, and no secondary containment. Bulk mineral composition of aggregate from two subsurface flow constructed wetlands was determined to consist solely of calcite using bulk powder X-ray diffraction. Some soil structure is developed in the aggregate and aggregate levels in wetlands drop at an estimated rate between 3 and 10 cm/year for overloaded wetlands owing to dissolution. Mineral composition from fresh aggregate samples commonly is a mixture of calcite and aragonite. Trace amounts of Pb, Zn, Co, and Cr were observed in fresh aggregate. Coefficients of permeability ( k) varied from 0.006 to 0.027 cm/s with an average values being 0.016 cm/s. Grain size analysis of fresh aggregate samples indicates there are unimodal and multimodal size distributions in the samples with modes in the coarse and fine sand being common. Investigations of other geologic media from the Reforma region indicate that a dolomite with minor amounts of Fe-oxide and palygorskite is abundant and may be a better aggregate source that the current materials used. A Ca-montmorillonite bed was identified in the Reforma region as well and this unit is suitable to serve as a clay liner to prevent leaks for new and existing wetland systems. These newly discovered geologic resources should aid in the improvement of subsurface flow constructed wetlands in the region. Although problems do exist in these wetlands with respect to design, these systems represent a successful implementation of constructed wetlands at a community level in developing regions.
Optimization of high-rate TN removal in a novel constructed wetland integrated with microelectrolysis system treating high-strength digestate supernatant.
Guo, Luchen; He, Keli; Wu, Shubiao; Sun, Hao; Wang, Yanfei; Huang, Xu; Dong, Renjie
The potential of high-rate TN removal in three aerated horizontal subsurface-flow constructed wetlands to treat high-strength anaerobic digestate supernatant was evaluated. Different strategies of intermittent aeration and effluent recirculation were applied to compare their effect on nitrogen depuration performance. Additional glucose supply and iron-activated carbon based post-treatment systems were established and examined, respectively, to further remove nitrate that accumulated in the effluents from aerated wetlands. The results showed that intermittent aeration (1 h on:1 h off) significantly improved nitrification with ammonium removal efficiency of 90% (18.1 g/(m(2)·d)), but limited TN removal efficiency (53%). Even though effluent recirculation (a ratio of 1:1) increased TN removal from 53% to 71%, the effluent nitrate concentration was still high. Additional glucose was used as a post-treatment option and further increased the TN removal to 82%; however, this implementation caused additional organic pollution. Furthermore, the iron-activated carbon system stimulated with a microelectrolysis process achieved greater than 85% effluent nitrate removal and resulted in 86% TN removal. Considering the high TN removal rate, aerated constructed wetlands integrated with a microelectrolysis-driven system show great potential for treating high-strength digestate supernatant. Copyright © 2016 Elsevier Ltd. All rights reserved.
Carbon and nitrogen dynamics and greenhouse gas emissions in constructed wetlands treating wastewater: a review
Jahangir, M. M. R.; Richards, K. G.; Healy, M. G.; Gill, L.; Müller, C.; Johnston, P.; Fenton, O.
The removal efficiency of carbon (C) and nitrogen (N) in constructed wetlands (CWs) is very inconsistent and frequently does not reveal whether the removal processes are due to physical attenuation or whether the different species have been transformed to other reactive forms. Previous research on nutrient removal in CWs did not consider the dynamics of pollution swapping (the increase of one pollutant as a result of a measure introduced to reduce a different pollutant) driven by transformational processes within and around the system. This paper aims to address this knowledge gap by reviewing the biogeochemical dynamics and fate of C and N in CWs and their potential impact on the environment, and by presenting novel ways in which these knowledge gaps may be eliminated. Nutrient removal in CWs varies with the type of CW, vegetation, climate, season, geographical region, and management practices. Horizontal flow CWs tend to have good nitrate (NO3-) removal, as they provide good conditions for denitrification, but cannot remove ammonium (NH4+) due to limited ability to nitrify NH4+. Vertical flow CWs have good NH4+ removal, but their denitrification ability is low. Surface flow CWs decrease nitrous oxide (N2O) emissions but increase methane (CH4) emissions; subsurface flow CWs increase N2O and carbon dioxide (CO2) emissions, but decrease CH4 emissions. Mixed species of vegetation perform better than monocultures in increasing C and N removal and decreasing greenhouse gas (GHG) emissions, but empirical evidence is still scarce. Lower hydraulic loadings with higher hydraulic retention times enhance nutrient removal, but more empirical evidence is required to determine an optimum design. A conceptual model highlighting the current state of knowledge is presented and experimental work that should be undertaken to address knowledge gaps across CWs, vegetation and wastewater types, hydraulic loading rates and regimes, and retention times, is suggested. We recommend that
Trace element removal from coal ash leachate by the 10-year-old construction wetland
Ye, Z.H.; Whiting, S.N.; Qian, J.H.; Lytle, C.M.; Lin, Z.-Q.; Terry, N. [University of California at Berkeley, Berkeley, CA (USA). Dept. of Plant and Microbial Biology
The study investigated the ability of a 10-year old constructed wetland to treat metal-contaminated leachate emanating from a coal ash pile at the Widows Creek electric utility, Alabama (USA). The two vegetated cells, which were dominated by cattail (Typha latifolia L.) and soft rush (Juncus effusus L.), were very effective at removing Fe and Cd from the wastewater, but less efficient for Zn, S, B, and Mn. The concentrations were decreased by up to 99% for Fe, 91% for Cd, 63% for Zn, 61% for S, 58% for Mn, and 50% for B. Higher pH levels ({gt} 6) in standing water substantially improved the removing efficiency of the wetland for Mn only. The belowground tissues of both cattail and soft rush had high concentrations of all elements; only for Mn, however, did the concentration in the shoots exceed those in the belowground tissues. The concentrations of trace elements in fallen litter were higher than in the living shoots, but lower than in the belowground tissues. The trace element accumulation in the plants accounts for less than 2.5% of the annual loading of each trace element into the wetland. The sediments were the primary sinks for the elements removed from the wastewater. Except for Mn, the concentrations of trace elements in the upper layer (0-5 cm) of the sediment profile tended to be higher than the lower layers (5-10 and 10-15 cm). The conclusion was that constructed wetlands are still able to efficiently remove metals in the long term (i.e. {gt} 10 years after construction). 34 refs., 7 figs., 2 tabs.
Pre-Construction Biogeochemical Analysis of Mercury in Wetlands Bordering the Hamilton Army Airfield (HAAF) Wetlands Restoration Site. Part 2
Best, Elly P; Fredrickson, Herbert L; Hintelmann, Holger; Clarisse, Olivier; Dimock, Brian; Lutz, Charles H; Lotufo, Gui R; Millward, Rod N; Bednar, Anthony J; Furey, John S
...) is working with the San Francisco Basin Regional Water Board, California State Coastal Conservancy, and San Francisco Bay Conservation and Development Commission to reconstruct wetlands at the former...
An Australian experience with a constructed wetland to treat ash dam water
M.W. Jensen; K.W. Riley [Delta Electricity (Australia)
In this paper, the effectiveness of a wetland system to treat water from a power station ash dam is discussed. The wetlands were constructed during 1996 and 1997. The length of the canals within the system is 1700 metres. There was a total planting of 35,000 tube stock of nine different species. In the summer of 1998, Typha orientalis colonised the system and is now the dominant species of emergent plant present. Water is introduced to the wetland from the return channel of the power station. The ash dam water is acidic (pH 4.5 5.5) and contains elevated levels of some trace elements including selenium, boron and fluorine. Of these three trace elements, selenium is regarded as the element of particular environmental concern. Since June 2000, there has been periodic sampling and analysis of both the inlet and outlet waters. The analytes include conductivity, pH, total organic carbon, Al, As, B, Ba, Ca, Cl, K, F, Fe, Mg, Mn, Na, selenite, total selenium, Si, Sr, sulfate and Zn. As well, plant material (stems and roots of the Typha) and sediments have been analysed for selenium. The results indicate boron and fluorine are not removed from the ash dam water by the processes occurring in the wetland. Selenium is partly removed. It appears that selenite is removed in preference to selenate. The development and operation of this experimental wetland is discussed in the context of a sustainable and ecologically sound system of minimising detrimental effects of the discharge of ash water. 26 refs., 4 tabs.
Comparative evaluation of low cost materials as constructed wetland filling media
Pinho, Henrique J. O.; Vaz, Mafalda M.; Mateus, Dina M. R.
Three waste materials from civil construction activities were assessed as low cost alternative filling materials used in Constructed Wetlands (CW). CW are green processes for wastewater treatment, whose design includes an appropriate selection of vegetation and filling material. The sustainability of such processes may be incremented using recovered wastes as filling materials. The abilities of the materials to support plant growth and to contribute to pollutants removal from wastewater were assessed and compared to expanded clay, a filling usually used in CW design. Statistical analysis, using one-way ANOVA and Welch's ANOVA, demonstrate that limestone fragments are a better choice of filling material than brick fragments and basalt gravel.
Impacts of multiple stressors on ecosystem function: Leaf decomposition in constructed urban wetlands
Mackintosh, Teresa J.; Davis, Jenny A.; Thompson, Ross M.
The impact of stormwater on stream biota is well documented, but less is known about the impacts on ecosystem processes, such as the breakdown of organic matter. This study sought to establish whether the degree of urbanisation affected rates of leaf-litter breakdown within constructed wetlands. A litter bag method was used to ascertain rate of decomposition along a gradient of urbanisation (total imperviousness, TI), in constructed wetlands in western and south-eastern Melbourne. A significant positive relationship between TI and breakdown rate was found in the south-eastern wetlands. The significant reduction in rate of invertebrate-mediated breakdown with increasing concentration of certain metals was consistent with other studies. However, overall there was an increase in rate of breakdown. Studies have shown that the effects of heavy metals can be negated if nutrient levels are high. Our results suggest that other parameters besides exposure to contaminants are likely to affect leaf litter breakdown. - Highlights: • There have been few studies on the effect of urbanisation on ecosystem function. • Rate of leaf litter breakdown increased moving along a gradient of urbanisation. • There was a reduction in invertebrate mediated breakdown with certain metals. • Results suggest other parameters besides contaminants affect leaf litter breakdown. - Certain heavy metals led to a decrease in leaf litter breakdown; however overall, there was a positive relationship between breakdown and increasing urbanisation.
Impacts of multiple stressors on ecosystem function: Leaf decomposition in constructed urban wetlands.
The impact of stormwater on stream biota is well documented, but less is known about the impacts on ecosystem processes, such as the breakdown of organic matter. This study sought to establish whether the degree of urbanisation affected rates of leaf-litter breakdown within constructed wetlands. A litter bag method was used to ascertain rate of decomposition along a gradient of urbanisation (total imperviousness, TI), in constructed wetlands in western and south-eastern Melbourne. A significant positive relationship between TI and breakdown rate was found in the south-eastern wetlands. The significant reduction in rate of invertebrate-mediated breakdown with increasing concentration of certain metals was consistent with other studies. However, overall there was an increase in rate of breakdown. Studies have shown that the effects of heavy metals can be negated if nutrient levels are high. Our results suggest that other parameters besides exposure to contaminants are likely to affect leaf litter breakdown. Copyright © 2015 Elsevier Ltd. All rights reserved.
Greenhouse gas production and efficiency of planted and artificially aerated constructed wetlands
Maltais-Landry, Gabriel [Departement des sciences biologiques, Universite de Montreal 90, rue Vincent-D' Indy, Montreal (Ciheam), H2V 2S9 (Canada); Institut de recherche en biologie vegetale, Universite de Montreal 4101, rue Sherbrooke Est, Montreal (Ciheam), H1X 2B2 (Canada)], E-mail: gabriel.maltais-landry@umontreal.ca; Maranger, Roxane [Departement des sciences biologiques, Universite de Montreal 90, rue Vincent-D' Indy, Montreal (Ciheam), H2V 2S9 (Canada)], E-mail: r.maranger@umontreal.ca; Brisson, Jacques [Departement des sciences biologiques, Universite de Montreal 90, rue Vincent-D' Indy, Montreal (Ciheam), H2V 2S9 (Canada); Institut de recherche en biologie vegetale, Universite de Montreal 4101, rue Sherbrooke Est, Montreal (Ciheam), H1X 2B2 (Canada)], E-mail: jacques.brisson@umontreal.ca; Chazarenc, Florent [Institut de recherche en biologie vegetale, Universite de Montreal 4101, rue Sherbrooke Est, Montreal (Ciheam), H1X 2B2 (Canada)
Greenhouse gas (GHG) emissions by constructed wetlands (CWs) could mitigate the environmental benefits of nutrient removal in these man-made ecosystems. We studied the effect of 3 different macrophyte species and artificial aeration on the rates of nitrous oxide (N{sub 2}O), carbon dioxide (CO{sub 2}) and methane (CH{sub 4}) production in CW mesocosms over three seasons. CW emitted 2-10 times more GHG than natural wetlands. Overall, CH{sub 4} was the most important GHG emitted in unplanted treatments. Oxygen availability through artificial aeration reduced CH{sub 4} fluxes. Plant presence also decreased CH{sub 4} fluxes but favoured CO{sub 2} production. Nitrous oxide had a minor contribution to global warming potential (GWP < 15%). The introduction of oxygen through artificial aeration combined with plant presence, particularly Typha angustifolia, had the overall best performance among the treatments tested in this study, including lowest GWP, greatest nutrient removal, and best hydraulic properties. - Methane is the main greenhouse gas produced in constructed wetlands and oxygen availability is the main factor controlling fluxes.
Robust biological nitrogen removal by creating multiple tides in a single bed tidal flow constructed wetland.
Hu, Yuansheng; Zhao, Yaqian; Rymszewicz, Anna
Achieving effective total nitrogen (TN) removal is one of the major challenges faced by constructed wetlands (CWs). To address this issue, multiple "tides" were proposed in a single stage tidal flow constructed wetland (TFCW). With this adoption, exceptional TN removal (85% on average) was achieved under a high nitrogen loading rate (NLR) of around 28 g Nm(-2)day(-1), which makes the proposed system an adequate option to provide advanced wastewater treatment for peri-urban communities and rural area. It was revealed that the multiple "tides" not only promoted TN removal performance, but also brought more flexibility to TFCWs. Adsorption of NH4(+)-N onto the wetland medium (during contact period) and regeneration of the adsorption capacity via nitrification (during bed resting) were validated as the key processes for NH4(+)-N conversion in TFCWs. Moreover, simultaneous nitrification denitrification (SND) was found to be significant during the bed resting period. These findings will provide a new foundation for the design and modeling of nitrogen conversion and oxygen transfer in TFCWs. © 2013.
Design and Season Influence Nitrogen Dynamics in Two Surface Flow Constructed Wetlands Treating Nursery Irrigation Runoff
Sarah A. White
Full Text Available Constructed wetlands (CWs are used to remediate runoff from a variety of agricultural, industrial, and urban sources. CW remediation performance is often evaluated at the laboratory scale over durations less than one year. The purpose of this study was to characterize the effect of CW design (cell depth and residence time on nitrogen (N speciation and fate across season and years in two free water surface wetlands receiving runoff from irrigated plant production areas at an ornamental plant nursery. Water quality (mg·L−1 of nitrate, nitrite, and ammonium, dissolved oxygen and oxidation reduction potential was monitored at five sites within each of two CWs each month over four years. Nitrate-N was the dominant form of ionic N present in both CWs. Within CW1, a deep cell to shallow cell design, nitrate comprised 86% of ionic N in effluent. Within CW2, designed with three sequential deep cells, nitrate comprised only 66% of total N and ammonium comprised 27% of total N in CW2 effluent. Differences in ionic N removal efficacies and shifts in N speciation in CW1 and CW2 were controlled by constructed wetland design (depth and hydraulic retention time, the concentration of nutrients entering the CW, and plant species richness.
Comparison of revegetation of a gas pipeline right-of-way in two forested wetland crossings involving conventional methods of pipeline installation and horizontal drilling, Nassau County, Florida
Van Dyke, G.D. [Trinity Christian Coll., Palos Heights, IL (United States). Dept. of Biology; Shem, L.M.; Zimmerman, R.E. [Argonne National Lab., IL (United States)
One year after pipeline installation, vegetation in the right-of-way (ROW) was inventoried at two stream floodplain crossings in Nassau County, Florida. Both sites were forested wetlands composed of Acer rubrum, Fraxinus caroliniana, Liquidamber styraciflua, Nyssa ogecho, Quercus laurifolia, and Taxodium distichum, together with other wetland trees. Pipeline installation across the Brandy Branch floodplain was by conventional ditching and backfill methods. Installation across the Deep Creek floodplain was by horizontal drilling after clearcutting the ROW. The latter method left tree stumps, understory vegetation, and soil layers intact, except for disruptions caused by logging. According to the inventory, vegetation at the drilled site was more diverse (nearly twice as many species occurring in the ROW as at the trenched site) and more robust (no unvegetated exposed soil compared to 15% at the trenched site). Differences between the ROW vegetation at the two sites can be attributed to both site differences and installation technologies used.
[Development characteristics of aquatic plants in a constructed wetland for treating urban drinking water source at its initial operation stage].
Zheng, Jun; Ma, Xin-Tang; Zhou, Lan; Zhou, Qing-Yuan; Wang, Zhong-Qiong; Wang, Wei-Dong; Yin, Cheng-Qing
The development characteristics and improvement measures of aquatic plants were studied in Shijiuyang Constructed Wetland (SCW) at its initial operation stage. SCW was a large-scale wetland aiming to help relieve the source water pollution in Jiaxing City. A checklist of vascular plants in SCW was built, and species composition, life forms, biomass and association distributions were examined. Our objectives were to examine the diversity and community structure of aquatic plants in SCW at its initial operation stage, and to find out the possible hydrophyte improvement measures. The survey results showed that there were 49 vascular plant species belonging to 41 genera, 25 families in SCW, which greatly exceeded the artificially transplanted 13 species. The life forms of present aquatic plants in SCW were dominated by hygrophilous plants (20 species) and emerged plants (17 species), which accounted for 75.5% of the total number of aquatic plants. The aquatic plants transplanted artificially were dominated by emerged plants (accounted for 69.2%), while those naturally developed were predominated by hygrophilous plants (accounted for 47.2%). The horizontal distribution of aquatic plant community in SCW was mixed in the form of mosaics, which made up typical association complex. Except association Aeschynomene indica L., the dominant species of other associations were all those transplanted artificially. The naturally grown species scattered throughout the SCW and only occupied a small percentage. A marked difference was detected on the species and species richness of aquatic plants in different regions of SCW. Biomass of aquatic plant associations in SCW was 167.7 t. SCW has shown a trend of succession heading for quick increase of plant diversity at the primary operation stage. This trend provides a good material base for the future stable community of aquatic plants in SCW. According to the current status of aquatic plants, some suggestions were put forward on the
Performance of free water surface flow constructed wetland with floating aquatic macrophytes
C. Soler
Full Text Available The aim of this study was to evaluate the behavior of constructed wetlands with aquatic macrophytes in decreasing the concentration of pollutants from urban effluents. A pilot-scale system with two coverages of floating plants and two hydraulic residence times, working with continuous flow laminar was built. The lower concentration of chemical oxygen demand and biological oxygen demand, were obtained with the lower coverage and higher hydraulic residence times. With little influence of the variables on the concentration of total nitrogen and total suspended solids, being the significant response for total phosphorus with the lowest plant coverage. There was a highly significant removal of total coliforms, regardless of coverage and in favor of higher hydraulic residence times. The use of free water surface wetlands is auspicious for sanitary control, showing low incidence on total nitrogen and total phosphorus.
Microbiology of a wetland ecosystem constructed to remediate mine drainage from a heavy metal mine.
Hallberg, Kevin B; Johnson, D Barrie
A pilot passive treatment plant (PPTP) was constructed to evaluate the potential of a composite wetland system to remediate acidic, metal-rich water draining the former Wheal Jane tin, in Cornwall, England. The treatment plant consists of three separate and controllable composite systems, each of which comprises a series of aerobic wetlands for iron oxidation and precipitation, a compost bioreactor for removing chalcophilic metals and to generate alkalinity, and rock filter ponds for removing soluble manganese and organic carbon. To understand the roles of microorganisms in remediating acid mine drainage (AMD) in constructed wetland ecosystems, populations of different groups of cultivatable acidophilic microbes in the various components of the Wheal Jane PPTP were enumerated over a 30-month period. Initially, moderately acidophilic iron-oxidising bacteria (related to Halothiobacillus neapolitanus) were found to be the major cultivatable microorganisms present in the untreated AMD, though later heterotrophic acidophiles emerged as the dominant group, on a numerical basis. Culturable microbes in the surface waters and sediments of the aerobic wetlands were similarly dominated by heterotrophic acidophiles, though both moderately and extremely acidophilic iron-oxidising bacteria were also present in significant numbers. The dominant microbial isolate in waters draining the anaerobic compost bioreactors was an iron- and sulfur-oxidising moderate acidophile that was closely related to Thiomonas intermedia. The acidophiles enumerated at the Wheal Jane PPTP accounted for 1% to 25% of the total microbial population. Phylogenetic analysis of 14 isolates from various components of the Wheal Jane PPTP showed that, whilst many of these bacteria were commonly encountered acidophiles, some of these had not been previously encountered in AMD and AMD-impacted environments.
Modeling of Aircraft Deicing Fluid Induced Biochemical Oxygen Demand in Subsurface-Flow Constructed Treatment Wetlands
Jukka A. Rintala, Christof Holliger, and Alla N. Nozhevnikova. "Evaluation of Kinetic Coefficients Using Intergrated Monod and Haldane Models for...Rousseau, Diederik P. L., Peter A Vanrolleghem, and Niels De Pauw. "Model-Based Design of Horizontal Subsurface Flow constructed Treatment
Constructing wetlands: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material
Saaltink, Rémon; Dekker, Stefan C.; Griffioen, Jasper; Wassen, Martin J.
Interest is growing in using soft sediment as a building material in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here the option of dredging some of the clay-rich lake-bed sediment and using it to construct 10.000 ha of wetland will soon go under construction. Natural processes will be utilized during and after construction to accelerate ecosystem development. Knowing that plants can eco-engineer their environment via positive or negative biogeochemical plant-soil feedbacks, we conducted a six-month greenhouse experiment to identify the key biogeochemical processes in the mud when Phragmites australis is used as an eco-engineering species. We applied inverse biogeochemical modeling to link observed changes in pore water composition to biogeochemical processes. Two months after transplantation we observed reduced plant growth and shriveling as well as yellowing of foliage. The N:P ratios of plant tissue were low and were affected not by hampered uptake of N but by enhanced uptake of P. Plant analyses revealed high Fe concentrations in the leaves and roots. Sulfate concentrations rose drastically in our experiment due to pyrite oxidation; as reduction of sulfate will decouple Fe-P in reducing conditions, we argue that plant-induced iron toxicity hampered plant growth, forming a negative feedback loop, while simultaneously there was a positive feedback loop, as iron toxicity promotes P mobilization as a result of reduced conditions through root death, thereby stimulating plant growth and regeneration. Given these two feedback mechanisms, we propose that when building wetlands from these mud deposits Fe-tolerant species are used rather than species that thrive in N-limited conditions. The results presented in this study demonstrate the importance of studying the biogeochemical properties of the building material and the feedback mechanisms between plant and soil prior to finalizing the design of the eco-engineering project.
Using cerium anomaly as an indicator of redox reactions in constructed wetland
Liang, R.
The study area, Chiayi County located in southern Taiwan, has highly developed livestock. The surface water has very low dissolved oxygen and high NH4. Under the situation, constructed wetland becomes the most effective and economic choice to treat the wastewater in the natural waterways. Hebao Island free surface constructed wetland started to operate in late 2006. It covers an area of 0.28 km2 and is subdivided into 3 major cells, which are sedimentation cell, 1st aeration cell with rooted plants and 2nd aeration cell with float plants. The water depth of cells ranges from 0.6 m to 1.2 m. The total hydraulic retention time is about a half day. In this study, the water samples were sequentially collected along the flow path. The results of hydrochemical analysis show that the untreated inflow water can be characterized with enriched NH4 (11 ppm), sulfate (6 ppm) and arsenic (50 ppb). The removal efficiency of NH4 in the first two cells is arsenic is still higher than the permissible limits recommended by WHO (10 ppb). The wetland operation should be tuned to take more arsenic away in the future. As demonstrated in the above, oxidation reaction is the most dominant mechanism to remove pollutants from the wastewater; therefore, dissolved oxygen is traditionally considered as an important indicator to evaluate the operation efficiency of wetland. However, it would need longer time to achieve equilibrium state of redox reaction involving dissolved oxygen due to the slower reaction rate. For example, the input water in this study has fairly high dissolved oxygen (5 ppm) but the NH4 content is still high, which indicates a non-equilibrium condition. In this study, the cerium anomaly is alternatively utilized to evaluate the water redox state. The results demonstrate that the input water has the negative cerium anomaly of -0.16. Along the flow path, the cerium negative anomaly does not change in the first two cells and dramatically becomes -0.23 in cell 3. The trend of
A Constructed Freshwater Wetland Shows Signs of Declining Net Ecosystem Exchange
Anderson, F. E.; Bergamaschi, B. A.; Windham-Myers, L.; Byrd, K. B.; Drexler, J. Z.; Fujii, R.
The USGS constructed a freshwater-wetland complex on Twitchell Island in the Sacramento-San Joaquin Delta (Delta), California, USA, in 1997 and maintained it until 2012 to investigate strategies for biomass accretion and reduction of oxidative soil loss. We studied an area of the wetland complex covered mainly by dense patches of hardstem bulrush (Schoenoplectus acutus) and cattails (Typha spp.), with smaller areas of floating and submerged vegetation, that was maintained at an average depth of 55 cm. Using eddy covariance measurements of carbon and energy fluxes, we found that the combination of water management and the region's Mediterranean climate created conditions where peak growing season daily means of net ecosystem exchange (NEE) reached -45 gCO2 m-2 d-1 and averaged around -30 gCO2 m-2 d-1 between 2002 through 2004. However, when measurements resumed in 2010, NEE rates were a fraction of the rates previously measured, approximately -6 gCO2 m-2 d-1. Interestingly, NEE rates in 2011 doubled compared to 2010 (-13 gCO2 m-2 d-1). Methane fluxes, collected in 2010 to assess a complete atmospheric carbon budget, were positive throughout the year, with daily mean flux values ranging from 50 to 300 mg CH4 m-2 d-1. As a result, methane flux reduced NEE values by approximately one-third, and when the global warming potential was considered, the wetland became a net global warming potential source. We found that carbon cycling in a constructed wetland is complex and can change over annual and decadal timescales. We investigated possible reasons for differences between flux measurements from 2002 to 2004 and those from 2010 and 2011: (1) changes in methodology, (2) differences in weather conditions, (3) differences in gross primary productivity relative to respiration rates, and (4) the amount of living plant tissue relative to brown accumulations of senesced plant litter. We hypothesize that large mats of senesced material within the flux footprint could have
Metal and metalloid removal in constructed wetlands, with emphasis on the importance of plants and standardized measurements: A review
Marchand, L.; Mench, M.; Jacob, D.L.; Otte, M.L.
This review integrates knowledge on the removal of metals and metalloids from contaminated waters in constructed wetlands and offers insight into future R and D priorities. Metal removal processes in wetlands are described. Based on 21 papers, the roles and impacts on efficiency of plants in constructed wetlands are discussed. The effects of plant ecotypes and class (monocots, dicots) and of system size on metal removal are addressed. Metal removal rates in wetlands depend on the type of element (Hg > Mn > Fe = Cd > Pb = Cr > Zn = Cu > Al > Ni > As), their ionic forms, substrate conditions, season, and plant species. Standardized procedures and data are lacking for efficiently comparing properties of plants and substrates. We propose a new index, the relative treatment efficiency index (RTEI), to quantify treatment impacts on metal removal in constructed wetlands. Further research is needed on key components, such as effects of differences in plant ecotypes and microbial communities, in order to enhance metal removal efficiency. - A new index, the relative treatment efficiency index (RTEI), to quantify treatment impacts on metal and metalloid removal in constructed wetlands.
Constructed wetland attenuation of nitrogen exported in subsurface drainage from irrigated and rain-fed dairy pastures.
Tanner, C C; Nguyen, M L; Sukias, J P S
Nitrogen removal performance is reported for constructed wetlands treating subsurface drainage from irrigated and rain-fed dairy pastures in North Island, New Zealand. Flow-proportional sampling of inflow and outflow concentrations were combined with continuous flow records to calculate mass balances for the wetlands. Drainage flows from the irrigated catchment were 2.5-4 fold higher and N exports up to 5 fold higher per unit area than for the rain-fed catchment. Hydraulic and associated N loadings to the wetlands were highly pulsed, associated with rainfall, soil water status, and irrigation events. Transient pulses of organic nitrogen were an important form of N loss from the rain-fed landscape in the first year, and were very effectively removed in the wetland (> 90%). Median nitrate concentrations of approximately 10 g m(-3) in the drainage inflows were reduced by 15-67% during passage through the wetlands and annual nitrate-N loads by 16-61% (38-31 7 g N m(-2)y(-1)). Generation in the wetlands of net ammoniacal-N and organic-N (irrigated site) partially negated reduction in nitrate-N loads. The results show that constructed wetlands comprising 1-2% of catchment area can provide moderate reductions in TN export via pastoral drainage, but performance is markedly influenced by variations in seasonal loading and establishment/maturation factors.
Role of dissimilatory sulfate reduction in wetlands constructed for acid coal mine drainage (AMD) treatment. Master's thesis
Taddeo, F.J.
Five constructed wetlands with different organic substrates were exposed to the same quantity/quality of acid mine drainage (AMD). During the 16-month exposure to AMD, all wetlands accumulated S in the forms of organic and reduced inorganic S and Fe in the form of iron sulfides. Iron sulfide and probably most of the organic S(C-bonded S) accumulation were end products of bacterial dissimilatory sulfate reduction. Results of study support the notion that sulfate reduction and accumulation of Fe sulfides contribute to Fe retention in wetlands exposed to AMD. Detailed information is provided
Integrated constructed wetland systems: design, operation, and performance of low-cost decentralized wastewater treatment systems.
Behrends, L L; Bailey, E; Jansen, P; Houke, L; Smith, S
Several different types of constructed wetland systems are being used as decentralized treatment systems including surface-flow, subsurface-flow, vertical-flow, and hybrid systems. Archetypical wetland systems have design strengths and weaknesses, and therefore it should be possible to design combined (integrated) systems to optimize a number of important treatment processes. This study provides comparative efficacy data for two integrated wetland treatment systems (IWTS) designed to enhance treatment of medium strength wastewater generated from a pilot-scale intensive fish farm. Results from the twenty eight months study included consistently high removal of COD (84% +) and ammonia nitrogen (93%) in both systems. Initially, phosphorus removal was also high (>90%) in both systems, but removal efficacy declined significantly over time. Nitrate removal was significantly better in the system that provided sequential aerobic and anoxic environments. Short hydraulic retention times coupled with sustained removal of COD and ammonia indicate that the ReCip components could be a least-cost wastewater treatment technology in the decentralized market sector.
Constructed wetlands and solar-driven disinfection technologies for sustainable wastewater treatment and reclamation in rural India: SWINGS project.
�lvarez, J A; �vila, C; Otter, P; Kilian, R; Isteni�, D; Rolletschek, M; Molle, P; Khalil, N; Ameršek, I; Mishra, V K; Jorgensen, C; Garfi, A; Carvalho, P; Brix, H; Arias, C A
SWINGS was a cooperation project between the European Union and India, aiming at implementing state of the art low-cost technologies for the treatment and reuse of domestic wastewater in rural areas of India. The largest wastewater treatment plant consists of a high-rate anaerobic system, followed by vertical and horizontal subsurface flow constructed wetlands with a treatment area of around 1,900 m 2 and a final step consisting of solar-driven anodic oxidation (AO) and ultraviolet (UV) disinfection units allowing direct reuse of the treated water. The implementation and operation of two pilot plants in north (Aligarh Muslim University, AMU) and central India (Indira Gandhi National Tribal University, IGNTU) are shown in this study. The overall performance of AMU pilot plant during the first 7 months of operation showed organic matter removal efficiencies of 87% total suspended solids, 95% 5-day biological oxygen demand (BOD 5 ) and 90% chemical oxygen demand, while Kjeldahl nitrogen removal reached 89%. The UV disinfection unit produces water for irrigation and toilet flushing with pathogenic indicator bacteria well below WHO guidelines. On the other hand, the AO disinfection unit implemented at IGNTU and operated for almost a year has been shown to produce an effluent of sufficient quality to be reused by the local population for agriculture and irrigation.
Effect of reversal of the flow direction on hydrodynamic characteristics and plants cultivated in constructed wetland systems
Gheila Corrêa Ferres Baptestini
Full Text Available The objective of the present study was to evaluate the effect of reversal of the flow direction, when used the surface flow as an operating criteria, on hydrodynamic characteristics and plants grown in horizontal subsurface-flow constructed wetland systems (HSF-CWs. For this purpose, six HSF-CWs were used: two non-cultivated (HSF-CWs 1 and 4, two cultivated with Tifton 85 grass (Cynodon spp. (HSF-CWs 2 and 5 and two cultivated with Alternanthera (Alternanthera philoxeroides (HSF-CWs 3 and 6. It was made a reversal in the flow direction of the HSF-CWs 1, 2 and 3. The reversal of the wastewater flow direction was performed when the superficial flow of the wastewater applied (SF reached 50% of the length of the HSF-CWs. There was a single reversal for each system, on different dates. Reversing the flow direction promoted distinction on the dry matter yield of Tifton 85 grass. This was not observed in HSF-CWs cultivated with Alternanthera. The reversal of the wastewater flow direction promoted, in principle, the extinction of the SF advance in the HSF-CWs, but did not prevent its return. Waiting for the SF to reach 50% of the length was not the best criterion for reversing the flow direction.
Pilot-scale comparison of constructed wetlands operated under high hydraulic loading rates and attached biofilm reactors for domestic wastewater treatment
Fountoulakis, M.S.; Terzakis, S.; Chatzinotas, A.; Brix, H.; Kalogerakis, N.; Manios, T.
Four different pilot-scale treatment units were constructed to compare the feasibility of treating domestic wastewater in the City of Heraklio, Crete, Greece: (a) a free water surface (FWS) wetland system, (b) a horizontal subsurface flow (HSF) wetland system, (c) a rotating biological contactor (RBC), and (d) a packed bed filter (PBF). All units operated in parallel at various hydraulic loading rates (HLR) ranging from 50% to 175% of designed operating HLR. The study was conducted during an 8 month period and showed that COD removal efficiency of HSF was comparable (> 75%) to that of RBC and PBF, whereas that of the FWS system was only 57%. Average nutrient removal efficiencies for FWS, HSF, RBC and PBF were 6%, 21%, 40% and 43%, respectively for total nitrogen and 21%, 39%, 41% and 42%, respectively for total phosphorus. Removals of total coliforms were lowest in FWS and PBF (1.3 log units) and higher in HSF and RBC (2.3 to 2.6 log units). HSF showed slightly lower but comparable effluent quality to that of RBC and PBF systems, but the construction cost and energy requirements for this system are significantly lower. Overall the final decision for the best non-conventional wastewater treatment system depends on the construction and operation cost, the area demand and the required quality of effluent
Effect of bacteria density and accumulated inert solids on the effluent pollutant concentrations predicted by the constructed wetlands model BIO_PORE
Samsó Campà , Roger; Blazquez, Jordi; Agullo Chaler, Nuria; Grau Barceló, Joan; Torres Cámara, Ricardo; García Serrano, Joan
Constructed wetlands are a widely adopted technology for the treatment of wastewater in small communities. The understanding of their internal functioning has increased at an unprecedented pace over recent years, in part thanks to the use of mathematical models. BIO_PORE model is one of the most recent models developed for constructed wetlands. This model was built in the COMSOL Multiphysics (TM) software and implements the biokinetic expressions of Constructed Wetlands Model 1 (CWM1) to desc...
Vertical flow constructed wetlands for domestic wastewater treatment on tropical conditions: effect of several design parameters
Bohorquez, Eliana; Paredes, Diego; Arias, Carlos Alberto
Vertical flow constructed wetlands (VFWC) design and operation takes into account several variables which affect performance its performance. These aspects had been evaluated and documented among others in countries like USA, Denmark, Austria. In contrast, VFCW had not been studied in tropical...... countries and, specifically in Colombia, design and operation parameters are not defined yet. The objective of this study was evaluate the effects of filter medium, the feeding frequency and Heliconia psittacorum presence, a typical local plant, on the domestic wastewater treatment in tropical conditions....
Wetland Water Cooling Partnership: The Use of Constructed Wetlands to Enhance Thermoelectric Power Plant Cooling and Mitigate the Demand of Surface Water Use
Apfelbaum, Steven L. [Applied Ecological Services Inc., Brodhead, WI (United States); Duvall, Kenneth W. [Sterling Energy Services, LLC, Atlanta, GA (United States); Nelson, Theresa M. [Applied Ecological Services Inc., Brodhead, WI (United States); Mensing, Douglas M. [Applied Ecological Services Inc., Brodhead, WI (United States); Bengtson, Harlan H. [Sterling Energy Services, LLC, Atlanta, GA (United States); Eppich, John [Waterflow Consultants, Champaign, IL (United States); Penhallegon, Clayton [Sterling Energy Services, LLC, Atlanta, GA (United States); Thompson, Ry L. [Applied Ecological Services Inc., Brodhead, WI (United States)
Through the Phase I study segment of contract #DE-NT0006644 with the U.S. Department of Energy's National Energy Technology Laboratory, Applied Ecological Services, Inc. and Sterling Energy Services, LLC (the AES/SES Team) explored the use of constructed wetlands to help address stresses on surface water and groundwater resources from thermoelectric power plant cooling and makeup water requirements. The project objectives were crafted to explore and develop implementable water conservation and cooling strategies using constructed wetlands (not existing, naturally occurring wetlands), with the goal of determining if this strategy has the potential to reduce surface water and groundwater withdrawals of thermoelectric power plants throughout the country. Our team's exploratory work has documented what appears to be a significant and practical potential for augmenting power plant cooling water resources for makeup supply at many, but not all, thermoelectric power plant sites. The intent is to help alleviate stress on existing surface water and groundwater resources through harvesting, storing, polishing and beneficially re-using critical water resources. Through literature review, development of conceptual created wetland plans, and STELLA-based modeling, the AES/SES team has developed heat and water balances for conventional thermoelectric power plants to evaluate wetland size requirements, water use, and comparative cooling technology costs. The ecological literature on organism tolerances to heated waters was used to understand the range of ecological outcomes achievable in created wetlands. This study suggests that wetlands and water harvesting can provide a practical and cost-effective strategy to augment cooling waters for thermoelectric power plants in many geographic settings of the United States, particularly east of the 100th meridian, and in coastal and riverine locations. The study concluded that constructed wetlands can have significant positive
Study of a pipe-scanning robot for use in post-construction evaluation during horizontal directional drilling.
Trenchless Technology has become an increasingly popular underground utility construction method, beginning in : the early 1900s with pipe jacking beneath railroad lines. One method, horizontal directional drilling (HDD), became : more common in the ...
Modelling Nitrogen Transformation in Horizontal Subsurface Flow ...
A mathematical model was developed to permit dynamic simulation of nitrogen interaction in a pilot horizontal subsurface flow constructed wetland receiving effluents from primary facultative pond. The system was planted with Phragmites mauritianus, which was provided with root zone depth of 75 cm. The root zone was ...
Comparison of grey water treatment performance by a cascading sand filter and a constructed wetland.
Kadewa, W W; Le Corre, K; Pidou, M; Jeffrey, P J; Jefferson, B
A novel unplanted vertical flow subsurface constructed wetland technology comprising three shallow beds (0.6 m length, 0.45 m width and 0.2 m depth) arranged in a cascading series and a standard single-pass Vertical Flow Planted Constructed Wetland (VFPCW, 6 m² and 0.7 m depth) were tested for grey water treatment. Particular focus was on meeting consent for published wastewater reuse parameters and removal of anionic surfactants. Treatment performance at two hydraulic loading rates (HLR) of 0.08, and 0.17 m³ m�² d�¹ were compared. Both technologies effectively removed more than 90% turbidity and more than 96% for organics with the prototype meeting the most stringent reuse standard of < 2 NTU and <10 mg/L. However, surfactant removal in the VFPCW was higher (76-85%) than in the prototype which only achieved more than 50% removal at higher loading rate. Generally, the prototype performed consistently better than the VFPCW except for surfactant removal. However, at higher loading rates, both systems did not meet the reuse standard of <1 mg L�¹ for anionic surfactants. This observation confirms that shallow beds provide a more oxidised environment leading to higher BOD₅ and COD removals. Presence of plants in the VFPCW led to higher anionic surfactant removal, through increased microbial and sorption processes.
Performance of a pilot-scale constructed wetland for stormwater runoff and domestic sewage treatment on the banks of a polluted urban river.
Guo, Weijie; Li, Zhu; Cheng, Shuiping; Liang, Wei; He, Feng; Wu, Zhenbin
To examine the performance of a constructed wetland system on stormwater runoff and domestic sewage (SRS) treatment in central east China, two parallel pilot-scale integrated constructed wetland (ICW) systems were operated for one year. Each ICW consisted of a down-flow bed, an up-flow bed and a horizontal subsurface flow bed. The average removal rates of chemical oxygen demand (CODCr), total suspended solids (TSS), ammonia (NH4(+)-N), total nitrogen (TN) and total phosphorus (TP) were 63.6, 91.9, 38.7, 43.0 and 70.0%, respectively, and the corresponding amounts of pollutant retention were approximately 368.3, 284.9, 23.2, 44.6 and 5.9 g m(-2) yr(-1), respectively. High hydraulic loading rate (HLR) of 200 mm/d and low water temperatures (<15 °C) resulted in significant decrease in removals for TP and NH4(+)-N, but had no significant effects on removals of COD and TSS. These results indicated that the operation of this ICW at higher HLR (200 mm/d) might be effective and feasible for TSS and COD removal, but for acceptable removal efficiencies of nitrogen and phosphorus it should be operated at lower HLR (100 mm/d). This kind of ICW could be employed as an effective technique for SRS treatment.
Macroinvertebrate assemblages and biodiversity levels: ecological role of constructed wetlands and artificial ponds in a natural park
Laura Sartori
Full Text Available Normal 0 14 false false false MicrosoftInternetExplorer4 Constructed wetlands play an important role in water supply, floodwater retention and nutrient removal, at the same time allowing the restoration of lost habitat and the preservation of biodiversity. There is little knowledge about the biodiversity that can be found in these artificial environments along time, especially at the invertebrate community level. Macroinvertebrate assemblages, water chemistry, morphology, and environmental characteristics of natural ponds, artificial pools and constructed wetlands in Parco Pineta (Northern Italy were studied to evaluate the effects of local factors on macroinvertebrate communities. The objective was to verify if each ecosystem could equally contribute to local biodiversity, regardless of its natural or artificial origin. Principal Components Analysis showed that ponds were divided into clusters, based on their morphology and their water quality, independently from their origin. The composition of macroinvertebrate communities was similar among natural wetlands and ponds artificially created to provide new habitats in the park, while it was different among natural wetlands and constructed wetlands created for wastewater treatment purposes. Biodiversity of natural ponds and constructed wetlands, evaluated using taxa richness, Shannon index, and Pielou index, was comparable. Canonical Correspondence Analysis highlighted differences in macroinvertebrate community composition and pointed out the relationships among macroinvertebrates and various environmental variables: habitat heterogeneity resulted as the most relevant factor that influences taxa richness. Water quality also affects the macroinvertebrate community structure. We determined that constructed wetlands with higher pollutant concentrations show different assemblage compositions but comparable overall macroinvertebrate biodiversity. Constructed wetlands became valuable ecological elements
The potential of acidophilic macroalgae as part of passive bioremediation technology for acid mine drainage in constructed wetlands
Cheng, Po-Hsun
Full Text Available macroalgae as part of passive bioremediation technology for acid mine drainage in constructed wetlands PH CHENG1,3, PJ OBERHOLSTER1,2, A-M BOTHA3 1CSIR Natural Resources and the Environment, PO Box 320, Stellenbosch, 7599, South Africa 2Department... of diverse benthic algal species to AMD provides the option to utilise them in AMD remediation as part of passive bioremediation technology in constructed wetlands. The purpose of the study was to investigate the bioaccumulation of metals and trace metal...
Studies on sustainability of simulated constructed wetland system for treatment of urban waste: Design and operation.
Upadhyay, A K; Bankoti, N S; Rai, U N
New system configurations and wide range of treatability make constructed wetland (CW) as an eco-sustainable on-site approach of waste management. Keeping this view into consideration, a novel configured three-stage simulated CW was designed to study its performance efficiency and relative importance of plants and substrate in purification processes. Two species of submerged plant i.e., Potamogeton crispus and Hydrilla verticillata were selected for this study. After 6 months of establishment, operation and maintenance of simulated wetland, enhanced reduction in physicochemical parameters was observed, which was maximum in the planted CW. The percentage removal (%) of the pollutants in three-stage mesocosms was; conductivity (60.42%), TDS (67.27%), TSS (86.10%), BOD (87.81%), NO3-N (81.28%) and PO4-P (83.54%) at 72 h of retention time. Submerged macrophyte used in simulated wetlands showed a significant time dependent accumulation of toxic metals (p ≤ 0.05). P. crispus accumulated the highest Mn (86.36 μg g(-1) dw) in its tissue followed by Cr (54.16 μg g(-1) dw), Pb (31.56 μg g(-1) dw), Zn (28.06 μg g(-1) dw) and Cu (25.76 μg g(-1) dw), respectively. In the case of H. verticillata, it was Zn (45.29), Mn (42.64), Pb (22.62), Cu (18.09) and Cr (16.31 μg g(-1) dw). Thus, results suggest that the application of simulated CW tackles the water pollution problem more efficiently and could be exploited in small community level as alternative and cost effective tools of phytoremediation. Copyright © 2016 Elsevier Ltd. All rights reserved.
Evaluation of an alternative method for wastewater treatment containing pesticides using solar photocatalytic oxidation and constructed wetlands.
Berberidou, Chrysanthi; Kitsiou, Vasiliki; Lambropoulou, Dimitra A; Antoniadis, Αpostolos; Ntonou, Eleftheria; Zalidis, George C; Poulios, Ioannis
The present study proposes an integrated system based on the synergetic action of solar photocatalytic oxidation with surface flow constructed wetlands for the purification of wastewater contaminated with pesticides. Experiments were conducted at pilot scale using simulated wastewater containing the herbicide clopyralid. Three photocatalytic methods under solar light were investigated: the photo-Fenton and the ferrioxalate reagent as well as the combination of photo-Fenton with TiO 2 P25, which all led to similar mineralization rates. The subsequent treatment in constructed wetlands resulted in further decrease of DOC and inorganic ions concentrations, especially of NO 3 - . Clopyralid was absent in the outlet of the wetlands, while the concentration of the detected intermediates was remarkably low. These findings are in good agreement with the results of phytotoxicity of the wastewater, after treatment with the ferrioxalate/wetlands process, which was significantly reduced. Thus, this integrated system based on solar photocatalysis and constructed wetlands has the potential to effectively detoxify wastewater containing pesticides, producing a purified effluent which could be exploited for reuse applications. Copyright © 2016 Elsevier Ltd. All rights reserved.
Suitability of macrophytes for nutrient removal from surface flow constructed wetlands receiving secondary treated sewage effluent in Queensland, Australia.
Greenway, M
From a botanical perspective the major difference between waste stabilisation ponds and wetlands is the dominance of algae or floating plants in the former and emergent plants in the latter. Algae, floating and submerged plants remove nutrients directly from the water column whereas emergent species remove nutrients from the sediment. Water depth is a crucial factor in determining which plant types will become established. Surface flow constructed wetlands offer the greatest potential to grow a wide variety of different types of macrophytes. In assessing the suitability of plant species for nutrient removal, consideration must be given not only to nutrient uptake for growth but also storage of nutrients as plant biomass. A survey of macrophytes in 15 surface flow constructed wetlands treating secondary effluent was conducted in Queensland; 63 native species and 14 introduced species were found. Emergent species have been able to tolerate deeper water than in their natural environment and permanent waterlogging. All species grew well in the higher nutrient enriched wastewater. Submerged, floating leaved-attached and free floating species had the highest tissue nutrient content, followed by aquatic creepers. All these species remove nutrients from the water column. Emergent species had lower nutrient content but a greater biomass and were therefore able to store more nutrients per unit area of wetland. In order to maximise the efficiency of constructed wetlands for nutrient removal, a range of species should be used. Native species should be selected in preference to introduced/exotic species.
Structural and metabolic responses of microbial community to sewage-borne chlorpyrifos in constructed wetlands.
Zhang, Dan; Wang, Chuan; Zhang, Liping; Xu, Dong; Liu, Biyun; Zhou, Qiaohong; Wu, Zhenbin
Long-term use of chlorpyrifos poses a potential threat to the environment that cannot be ignored, yet little is known about the succession of substrate microbial communities in constructed wetlands (CWs) under chlorpyrifos stress. Six pilot-scale CW systems receiving artificial wastewater containing 1mg/L chlorpyrifos were established to investigate the effects of chlorpyrifos and wetland vegetation on the microbial metabolism pattern of carbon sources and community structure, using BIOLOG and denaturing gradient gel electrophoresis (DGGE) approaches. Based on our samples, BIOLOG showed that Shannon diversity (H') and richness (S) values distinctly increased after 30days when chlorpyrifos was added. At the same time, differences between the vegetated and the non-vegetated systems disappeared. DGGE profiles indicated that H' and S had no significant differences among four different treatments. The effect of chlorpyrifos on the microbial community was mainly reflected at the physiological level. Principal component analysis (PCA) of both BIOLOG and DGGE showed that added chlorpyrifos made a difference on test results. Meanwhile, there was no difference between the vegetation and no-vegetation treatments after addition of chlorpyrifos at the physiological level. Moreover, the vegetation had no significant effect on the microbial community at the genetic level. Comparisons were made between bacteria in this experiment and other known chlorpyrifos-degrading bacteria. The potential chlorpyrifos-degrading ability of bacteria in situ may be considerable. Copyright © 2016. Published by Elsevier B.V.
Purification of fuel and nitrate contaminated ground water using a free water surface constructed wetland plant
Machate, T.; Heuermann, E.; Schramm, K.W.; Kettrup, A.
Contaminated ground water from a former coke plant site was purified in a free water surface (FWS) constructed wetland plant during a 3-mo short-term experiment. The pilot plant (total surface area 27 m{sup 2}) was filled with a 1 m thick lava-gravel substrate planted with cattail (Typha spp.) and bulrush (Scirpus lacustrls). Major contaminants were low to moderate concentrations of polycyclic aromatic hydrocarbons, BTEX, nitrate, and nitrite. The wetland was dosed at hydraulic loading rates of q{sub A} = 4.8 and 9.6 cm d{sup {minus}1} with a hydraulic residence time (HRT) of 13.7 and 6.8 d. The surface removal rates of PAH were between 98.8 and 1914 mg m{sup {minus}2} d{sup {minus}1}. Efficiency was always {gt}99%. Extraction of lava gravel showed that approx. 0.4% of the applied PAH were retained on the substratum. The ratio of {Sigma}2,3-ring PAH and {Sigma}4,5,6-ring PAH showed a shift from 1:0.11 in water to 1:2.5 in lava. The removal of BTEX was {gt}99%, but might be in part due to volatilization. The efficiency in the removal of nitrate was 91% and of nitrite was 97%. Purification performance was not influenced by hydraulic loading rates or after die-back of the macrophytes.
Nitrous oxide emission from polyculture constructed wetlands: Effect of plant species
Wang Yanhua [School of Environmental Science and Engineering, Shanghai Jiaotong University, 800 Dong Chuan Road, Min Hang, Shanghai 200240 (China); Inamori, Ryuhei [Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Kong Hainan [School of Environmental Science and Engineering, Shanghai Jiaotong University, 800 Dong Chuan Road, Min Hang, Shanghai 200240 (China)], E-mail: remanda@126.com; Xu Kaiqin [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506 (Japan); State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan Unviversity, Wuhan 430072 (China); Inamori, Yuhei [Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Kondo, Takashi [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506 (Japan); Zhang Jixiang [School of Economics and Management, Southeast University, Nanjing, Jiangsu 210096 (China)
Loss of nitrogen from the soil-plant system has raised environmental concern. This study assessed the fluxes of nitrous oxide (N{sub 2}O) in the subsurface flow constructed wetlands (CWs). To better understand the mechanism of N{sub 2}O emission, spatial distribution of ammonia-oxidizing bacteria (AOB) in four kinds of wetlands soil were compared. N{sub 2}O emission data showed large temporal and spatial variation ranging from -5.5 to 32.7 mg N{sub 2}O m{sup -2} d{sup -1}. The highest N{sub 2}O emission occurred in the cell planted with Phragmites australis and Zizania latifolia. Whereas, the lower emission rate were obtained in the cell planted with P. australis and Typha latifolia. These revealed that Z. latifolia stimulated the N{sub 2}O emission. Transportation of more organic matter and oxygen for AOB growth may be the reason. The study of AOB also supported this result, indicating that the root structure of Z. latifolia was favored by AOB for N{sub 2}O formation. - Zizania latifolia has a large contribution to global warming.
Use of constructed wetland for the removal of heavy metals from industrial wastewater.
Khan, Sardar; Ahmad, Irshad; Shah, M Tahir; Rehman, Shafiqur; Khaliq, Abdul
This study was conducted to investigate the effectiveness of a continuous free surface flow wetland for removal of heavy metals from industrial wastewater, in Gadoon Amazai Industrial Estate (GAIE), Swabi, Pakistan. Industrial wastewater samples were collected from the in-let, out-let and all cells of the constructed wetland (CW) and analyzed for heavy metals such as lead (Pb), cadmium (Cd), iron (Fe), nickel (Ni), chromium (Cr) and copper (Cu) using standard methods. Similarly, samples of aquatic macrophytes and sediments were also analyzed for selected heavy metals. Results indicate that the removal efficiencies of the CW for Pb, Cd, Fe, Ni, Cr, and Cu were 50%, 91.9%, 74.1%, 40.9%, 89%, and 48.3%, respectively. Furthermore, the performance of the CW was efficient enough to remove the heavy metals, particularly Cd, Fe, and Cu, from the industrial wastewater fed to it. However, it is suggested that the metal removal efficiency of the CW can be further enhanced by using proper management of vegetation and area expansion of the present CW.
Constructed Wetlands for Combined Sewer Overflow Treatment—Comparison of German, French and Italian Approaches
Daniel Meyer
Full Text Available Combined sewer systems are designed to transport stormwater surface run off in addition to the dry weather flows up to defined limits. In most European countries, hydraulic loads greater than the design flow are discharged directly into receiving water bodies, with minimal treatment (screening, sedimentation, or with no treatment at all. One feasible solution to prevent receiving waters from strong negative impacts seems to be the application of vertical flow constructed wetlands. In Germany, first attempts to use this ecological technology were recognized in early 1990s. Since then, further development continued until a high level of treatment performance was reached. During recent years the national "state-of-the-art� (defined in 2005 was adapted in other European countries, including France and Italy. Against the background of differing national requirements in combined sewer system design, substantial developmental steps were taken. The use of coarser filter media in combination with alternating loadings of separated filter beds allows direct feedings with untreated combined runoff. Permanent water storage in deep layers of the wetland improves the system's robustness against extended dry periods, but contains operational risks. Besides similar functions (but different designs and layouts, correct dimensioning of all approaches suffers from uncertainties in long-term rainfall predictions as well as inside sewer system simulation tools.
Effect of N:P ratio of influent on biomass, nutrient allocation, and recovery of Typha latifolia and Canna 'Bengal Tiger' in a laboratory-scale constructed wetland
Constructed wetlands (CWs) are an effective low-technology approach for treating agricultural, industrial, and municipal wastewater. Recovery of phosphorous by constructed wetland plants may be affected by wastewater nitrogen to phosphorous (N:P) ratios. Varying N:P ratios were supplied to Canna '...
Comparisons of mosquito populations before and after construction of a wetland for water quality improvement in Pitt County, North Carolina, and data-reliant vectorborne disease management.
Anderson, Alice L; O'Brien, Kevin; Hartwell, Megan
Wetlands serve an important purpose in flood control and water quality, but constructed-wetland sites also provide habitats for mosquito breeding. Communities near constructed-wetland sites often raise a "mosquito" objection when constructed wetlands are proposed. Wildlife and wetland advocates can confuse the public by making unsubstantiated claims about natural predators eliminating or controlling mosquito problems in a constructed wetland. Management of constructed-wetland mosquito habitat, with adequate mosquito surveillance and data analysis, can help lead to a successful project and satisfied citizens. The cooperative project described in this paper, was conducted in the town of Simpson, North Carolina, and was designed to determine the mosquito population impact of wetland construction at Mill Branch Stream, a small tributary of the Tar River in Eastern North Carolina. In the authors' analysis of three years of mosquito surveillance data, month (time of year standing in for temperature and day length) was a significant factor in regression analysis for mosquito numbers, but rainfall was not. Numbers of mosquitoes were not found to be significantly higher after construction than before construction.
Nitrogen Transformation and Removal in Horizontal Surface Flow ...
The potential use of Constructed Mangrove Wetlands (CMWs) as a cheaper, effective and appropriate method for Nitrogen removal from domestic sewage of coastal zone in peri-urban cities was investigated from August 2007 to. September, 2008. Field investigations were made on horizontal surface flow constructed ...
Quantifying the impacts of road construction on wetlands loss : preliminary analysis
Over the past decades, the role of federal programs in the generation of wetlands losses has received much attention. One of the federal programs most responsible for wetlands losses and degradation is believed to be the Federal Aid Highway Program. ...
Urban wastewater process by aerobic constructed wetland; Depuracion de aguas residuales urbanas utilizando un humedal artificial aerobio
Gil Rodriguez, M.
In this paper the experiences of urban wastewater treatment are shown in an aerobic constructed wetland, using phragmites australis.They were carried out changes on the design and operation of aerobic constructed wetlands of subsurface flow, in order to increase denitrification and biodegradation rate and to diminish the surface of the installation. the flow was channeled through a long and narrow channel to get bigger biodegradation rate to approach to the plug flow performance. the active space of process consists of two sites, one first anoxic in which denitrification takes place, and in the other one the wetland in oxygenated environment the organic matters of the wastewater are consumed by biodegradation and it takes place nitrification, and utilization of nitrates and phosphates by the vegetable culture. (Author) 14 refs.
AVALIAÇÃO DAS CONDIÇÕES HIDRODINÂMICAS DE WETLANDS DE ESCOAMENTO HORIZONTAL SUBSUPERFICIAL (UNIDADES PLANTADA E NÃO PLANTADA
André Cordeiro De Paoli
Full Text Available 800x600 Este trabalho teve o objetivo de avaliar o comportamento hidrodinâmico de duas wetlands construídas (WC de escoamento horizontal subsuperficial e analisar comparativamente os respectivos parâmetros hidrodinâmicos gerados em cada sistema. No intuito de entender esse comportamento, foi realizado um teste simultâneo com elemento traçador (82Br nas duas wetlands, uma plantada (WP e outra não plantada (WNP, recebendo efluente sanitário de reator UASB (equivalente populacional de 50 habitantes cada. Os estudos foram efetuados após as unidades estarem em operação por cerca de 2 anos e apresentando escoamento superficial indesejado no início do leito de ambas as unidades, com maior escoamento superficial na WP (aproximadamente o dobro da WNP. Nesse trabalho são apresentados resultados comparativos relacionados às condições hidrodinâmicas dos dois sistemas e seus respectivos parâmetros obtidos. As duas unidades de wetlands apresentaram tempo de detenção hidráulica (TDH médio inferior ao teórico calculado em projeto, com valor ligeiramente superior para a WNP. As duas unidades apresentaram condições hidrodinâmicas similares , com a WNP apresentando número de dispersão (d apenas um pouco inferior e número de tanques em série ligeiramente superior, comparado com a WP. Normal 0 21 false false false PT-BR X-NONE X-NONE MicrosoftInternetExplorer4
Impact of heavy metal toxicity and constructed wetland system as a tool in remediation.
Usharani, B; Vasudevan, N
The objective of this review is to throw light upon the global concern of heavy metal-contaminated sites and their remediation through an ecofriendly approach. Accumulated heavy metals in soil and water bodies gain entry through the food chain and pose serious threat to all forms of life. This has engendered interest in phytoremediation techniques where hyperaccumulators are used. Constructed wetland has a pivotal role and is a cost-effective technique in the remediation of heavy metals. Metal availability and mobility are influenced by the addition of chelating agents, which enhance the availability of metal uptake. This review helps in identifying the critical knowledge gaps and areas to enhance research in the future to develop strategies such as genetically engineered hyperaccumulators to attain an environment devoid of heavy metal contamination.
Strategies and techniques to enhance constructed wetland performance for sustainable wastewater treatment.
Wu, Haiming; Fan, Jinlin; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Liang, Shuang; Hu, Zhen; Liu, Hai
Constructed wetlands (CWs) have been used as an alternative to conventional technologies for wastewater treatment for more than five decades. Recently, the use of various modified CWs to improve treatment performance has also been reported in the literature. However, the available knowledge on various CW technologies considering the intensified and reliable removal of pollutants is still limited. Hence, this paper aims to provide an overview of the current development of CW strategies and techniques for enhanced wastewater treatment. Basic information on configurations and characteristics of different innovations was summarized. Then, overall treatment performance of those systems and their shortcomings were further discussed. Lastly, future perspectives were also identified for specialists to design more effective and sustainable CWs. This information is used to inspire some novel intensifying methodologies, and benefit the successful applications of potential CW technologies.
Use of multiple water surface flow constructed wetlands for non-point source water pollution control.
Li, Dan; Zheng, Binghui; Liu, Yan; Chu, Zhaosheng; He, Yan; Huang, Minsheng
Multiple free water surface flow constructed wetlands (multi-FWS CWs) are a variety of conventional water treatment plants for the interception of pollutants. This review encapsulated the characteristics and applications in the field of ecological non-point source water pollution control technology. The roles of in-series design and operation parameters (hydraulic residence time, hydraulic load rate, water depth and aspect ratio, composition of influent, and plant species) for performance intensification were also analyzed, which were crucial to achieve sustainable and effective contaminants removal, especially the retention of nutrient. The mechanism study of design and operation parameters for the removal of nitrogen and phosphorus was also highlighted. Conducive perspectives for further research on optimizing its design/operation parameters and advanced technologies of ecological restoration were illustrated to possibly interpret the functions of multi-FWS CWs.
The use of halophytic plants for salt phytoremediation in constructed wetlands.
Farzi, Abolfazl; Borghei, Seyed Mehdi; Vossoughi, Manouchehr
This research studied the use of constructed wetlands (CWs) to reduce water salinity. For this purpose, three halophytic species of the Chenopodiaceae family (Salicornia europaea, Salsola crassa, and Bienertia cycloptera) that are resistant to saline conditions were planted in the CWs, and experiments were conducted at three different salinity levels [electrical conductivity (EC)∼2, 6, 10 dS/m]. EC and concentrations of calcium (Ca), magnesium (Mg), sodium (Na), and chlorine (Cl) were measured before and after phytoremediation with a retention time of 1 week. The results suggested that these plants were able to grow well and complete their life cycles at all the salinity levels within this study. Moreover, these plants reduced the measured parameters to acceptable levels. Therefore, these plants can be considered good options for salt phytoremediation.
Role of Plants in a Constructed Wetland: Current and New Perspectives
Amit Gross
Full Text Available The role of plants in the treatment of effluents by constructed wetland (CW systems is under debate. Here, we review ways in which plants can affect CW processes and suggest two novel functions for plants in CWs. The first is salt phytoremediation by halophytes. We have strong evidence that halophytic plants can reduce wastewater salinity by accumulating salts in their tissues. Our studies have shown that Bassia indica, a halophytic annual, is capable of salt phytoremediation, accumulating sodium to up to 10% of its dry weight. The second novel use of plants in CWs is as phytoindicators of water quality. We demonstrate that accumulation of H2O2, a marker for plant stress, is reduced in the in successive treatment stages, where water quality is improved. It is recommended that monitoring and management of CWs consider the potential of plants as phytoremediators and phytoindicators.
Effects of bleaching wastewater irrigation on soil quality of constructed reed wetlands
Cheng Ding
Full Text Available Constructed reed wetland microcosms (CRWs in a lab of east China have been irrigated with bleaching wastewater per month for a reed growth season. The soil physicochemical properties, enzyme activities (i.e. urease, invertase, polyphenol oxidase, alkaline phosphatase and cellulase and soil microbial diversity were assayed before and after the exposure experiment. Compared to the river water irrigated controls (CKs, bleaching wastewater application has no marked influence on soil pH, but significantly increased soil Na+, total halogen and absorbable organic halogen (AOX contents, which induced the increasing of soil electrical conductivity. Furthermore, soil enzyme activities displayed significant variation (except for polyphenol oxidase. Bleaching wastewater irrigation decreased Sorenson's pairwise similarity coefficient (Cs, which indicated the changes of the structure of bacterial and fungal communities. However, only the diversity of bacterial community was inhibited and has no effect on the diversity of fungal community, as evidenced by the calculated Shannon–Wiener index (H.
Salinity and pH effects on floating and emergent macrophytes in a constructed wetland.
Hadad, H R; Mufarrege, M M; Di Luca, G A; Maine, M A
Salvinia herzogii, Pistia stratiotes and Eichhornia crassipes (floating species) were the dominant macrophytes in a constructed wetland (CW) over the first years of operation. Later, the emergent Typha domingensis displaced the floating species, becoming dominant. The industrial effluent treated at this CW showed high pH and salinity. The aim of this work was to study the tolerance of floating species and T. domingensis exposed to different pH and salinity treatments. Treatments at pH 8, 9, 10 and 11 and salinities of 2,000; 3,000; 4,000; 6,000; and 8,000 mg L -1 were performed. Floating macrophytes were unable to tolerate the studied pH and salinity ranges, while T. domingensis tolerated higher pH and salinity values. Many industrial effluents commonly show high pH and salinity. T. domingensis demonstrated to be a suitable macrophyte to treat this type of effluents.
Accumulation of Metals and Boron in Phragmites australis Planted in Constructed Wetlands Polishing Real Electroplating Wastewater.
Sochacki, Adam; Guy, Bernard; Faure, Olivier; Surmacz-Górska, Joanna
The concentration of metals (Al, Cu, Fe, Mn, Ni, Zn) and B were determined in the above- and belowground biomass of Phragmites australis collected from the microcosm constructed wetland system used for the polishing of real electroplating wastewater. Translocation factor and bioconcentration factor were determined. Pearson correlation test was used to determine correlation between metal concentration in substrate and above- and belowground parts of Phragmites australis. The obtained results suggested that Phragmites australis did not play a major role as an accumulator of metals. It was observed also that the substrate could have exerted an effect on the translocation of Ni, Cu, Zn and Mn. The analysed concentrations of metals and B in biomass were in the range or even below the concentrations reported in the literature with the exception of Ni. The aboveground biomass was found suitable as a composting input in terms of metals concentrations.
Furosemide removal in constructed wetlands: Comparative efficiency of LECA and Cork granulates as support matrix.
Machado, A I; Dordio, A; Fragoso, R; Leitão, A E; Duarte, E
The removal efficiency of LECA and cork granulates as support matrix for pharmaceuticals active compounds in a constructed wetland system was investigated using the diuretic drug Furosemide. Kinetics studies were performed testing three different concentrations of Furosemide in an ultrapure water matrix, along seven days. LECA achieved higher removal values compared to cork granulates. However, cork granulates presented a higher removal in the first 24 h of contact time compared to the other adsorbent. The kinetic studies showed that LECA and cork granulates have different adsorption behaviours for Furosemide which is controlled by different adsorption mechanisms. Both materials showed good removal efficiencies and a combination of the two should be further explored in order to applied both materials as support matrix to cope with different furosemide concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.
Treatment of high organic content wastewater from food-processing industry with the French vertical flow constructed wetland system.
Paing, J; Serdobbel, V; Welschbillig, M; Calvez, M; Gagnon, V; Chazarenc, F
This study aimed at determining the treatment performances of a full-scale vertical flow constructed wetlands designed to treat wastewater from a food-processing industry (cookie factory), and to study the influence of the organic loading rate. The full-scale treatment plant was designed with a first vertical stage of 630 m², a second vertical stage of 473 m² equipped with a recirculation system and followed by a final horizontal stage of 440 m². The plant was commissioned in 2011, and was operated at different loading rates during 16 months for the purpose of this study. Treatment performances were determined by 24 hour composite samples. The mean concentration of the raw effluent was 8,548 mg.L(-1) chemical oxygen demand (COD), 4,334 mg.L(-1) biochemical oxygen demand (BOD5), and 2,069 mg.L(-1) suspended solids (SS). Despite low nutrients content with a BOD5/N/P ratio of 100/1.8/0.5, lower than optimum for biological degradation (known as 100/5/1), mean removal performances were very high with 98% for COD, 99% for BOD5 and SS for the two vertical stages. The increasing of the organic load from 50 g.m(-2).d(-1) COD to 237 g.m(-2).d(-1) COD (on the first stage) did not affect removal performances. The mean quality of effluent reached French standards (COD < 125 mg.L(-1), BOD5 < 25 mg.L(-1), SS < 35 mg.L(-1)).
Treatment of segregated black/grey domestic wastewater using constructed wetlands in the Mediterranean basin: the zer0-m experience.
Masi, F; El Hamouri, B; Abdel Shafi, H; Baban, A; Ghrabi, A; Regelsberger, M
Concerns about water shortage and pollution have received increased attention over the past few years, especially in developing countries with warm climate. In order to help local water management in these countries, the Euro-Mediterranean Regional Programme (MEDA) has financed the Zer0-m project (E-mail: www.zer0-m.org). As a part of this project, several constructed wetland (CW) pilot systems with different pre-treatments have been implemented in four Technological Demonstration Centres in Egypt, Morocco, Tunisia and Turkey. The aim of this research was to establish appropriate designs for treatment of segregated domestic black (BW) and grey water (GW). We tested several different multistage CW configurations, consisting of horizontal and vertical subsurface flow CW for secondary treatment and free water systems as tertiary stage. CW removal efficiencies of TSS, COD, BOD(5), N-NH(4)(+), N-NO(3)(-), N(tot), total coliforms (TC) were evaluated for each of the implemented systems. The results from this study demonstrate the potential of CWs as a suitable technology for treating segregated domestic wastewater. A very efficient COD reduction (up to 98%) and nitrification (92-99%) was achieved for BW and GW in all systems. CW effluent concentrations were below 15 mg/L for BOD(5), 1 mg/L for N-NO(3)(-) and 0.5 mg/L for N-NH(4)(+) together with acceptable TC counts. Based on these results, we suggest adopting the design parameters used in this study for the treatment of segregated wastewater in the Mediterranean area.
Removal kinetics of organic matter and nitrogen using Microbial Electrochemical based – Constructed Wetlands (iMETland)
Ramírez Vargas, Carlos Andrés; Arias, Carlos Alberto; Carvalho, Pedro
In recent years the combination of Constructed Wetlands and Microbial Fuel Cell (MFC), has led to an innovative set- up for wastewater treatment and energy harvesting, relaying on electrodes and external circuits (CW – MFC). Based on this approach, a new concept is being developed to create the M...
Comparing the Efficiency of Stabilization Ponds and Subsurface Constructed Wetland in Domestic Sewage Treatment in City of Yazd
hadi Eslami
Full Text Available Wastewater is one of the most important contributors to water pollution on the one hand, while it has the potential to serve as an alternative source of water if subjected to proper treatment, on the other. The present study was designed to compare the removal efficiencies of stabilization ponds and subsurface constructed wetlands in the treatment of urban wastewater in Yazd. For this purpose, 72 samples were collected at the inlet and outlet of a constructed wetland as well as 72 from the inlet and outlet of stabilization ponds over a period of one year. The samples were subjected to identical tests and the results were compared. The removal efficiencies for BOD5, COD, TSS, NH4-N, NO3-N, and PO4 in the stabilization ponds were 79.7, 79.6, 44.4, 57, 0, and 42.5 percent, respectively. The same parameters for the constructed wetland system were 80.7, 81.5, 77.7, 9.9, 34, and 59.4, respectively. Moreover, BOD5, COD, TSS, and PO4 removal efficiencies were higher in autumn and summer. From these results, it may be concluded that constructed wetlands are more commercially viable than stabilization ponds both in terms of performance and cost-effectiveness.
Economic feasibility of surface flow constructed (SFCW) wetlands for reduction of water pollution from agricultural fields in Denmark
Gachango, Florence Gathoni; Pedersen, Søren Marcus; Kjaergaard, Charlotte
Constructed wetlands have been proposed as cost effective and more targeted technologies in the reduction of nitrogen and phosphorous water pollution in drainage losses from agricultural fields in Denmark. Using two pig farms and one dairy farm situated in a pumped lowland catchment as study cases...
Preliminary evaluation of a constructed wetland for treating extremely alkaline (pH 12) steel slag drainage.
Mayes, W M; Aumônier, J; Jarvis, A P
High pH (> 12) leachates are an environmental problem associated with drainage from lime (CaO)-rich industrial residues such as steel slags, lime spoil and coal combustion residues. Recent research has highlighted the potential for natural ('volunteer') wetlands to buffer extremely alkaline influent waters. This appears ascribable to high CO(2) partial pressures in the wetland waters from microbial respiration, which accelerates precipitation of calcium carbonate (CaCO(3)), and the high specific surface area for mineral precipitation offered by macrophytes. The research presented here builds on this and provides preliminary evaluation of a constructed wetland built in March 2008 to buffer drainage from steel slag heaps in north-east England. The drainage water from the slag mounds is characterised by a mean pH of 11.9, high concentrations of Ca (up to 700 mg/L), total alkalinity (up to 800 mg/L as CaCO(3)) and are slightly brackish (Na = 300 mg/L; Cl = 400 mg/L) reflecting native groundwaters at this coastal setting. Documented calcite precipitation rates (mean of 5 g CaCO(3)/m(2)/day) from nearby volunteer sites receiving steel slag drainage were used to scale the constructed wetland planted with Phragmites australis; a species found to spontaneously grow in the vicinity of the discharge. Improved performance of the wetland during summer months may at least in part be due to biological activity which enhances rates of calcite precipitation and thus lowering of pH. Secondary Ca-rich precipitates also serve as a sink for some trace elements present at low concentrations in the slag leachate such as Ni and V. The implications for scaling and applying constructed wetlands for highly alkaline drainage are discussed.
Regeneration of vegetation on wetland crossings for gas pipeline rights-of-way one year after construction
Shem, L.M.; Zimmerman, R.E.; Zellmer, S.D.; Van Dyke, G.D.; Rastorfer, J.R.
Four wetland crossings of gas pipeline rights-of-way (ROWs), located in Florida, Michigan, New Jersey, and New York, were surveyed for generation of vegetation roughly one year after pipeline construction was completed. Conventional trench-and-fill construction techniques were employed for all four sites. Estimated areal coverage of each species by vegetative strata within transect plots was recorded for plots on the ROW and in immediately adjacent wetlands undisturbed by construction activities. Relative success of regeneration was measured by percent exposed soil, species diversity, presence of native and introduced species, and hydric characteristics of the vegetation. Variable site factors included separation and replacement of topsoil, final grading of the soil, application of seed and fertilizer, and human disturbance unrelated to construction. Successful regeneration exhibited greater dependency on the first three factors listed
Ammonia, phosphate, phenol, and copper(II) removal from aqueous solution by subsurface and surface flow constructed wetland.
Mojiri, Amin; Ahmad, Zakiah; Tajuddin, Ramlah Mohd; Arshad, Mohd Fadzil; Gholami, Ali
Water pollution is a global problem. During current study, ammonia, phosphate, phenol, and copper(II) were removed from aqueous solution by subsurface and surface flow constructed wetland. In current investigation, distilled water was polluted with four contaminants including ammonia, phosphate, copper (Cu), and phenol. Response surface methodology and central composite design were applied to optimize pollutant removal during treatment by subsurface flow constructed wetland (SSFCW). Contact time (12 to 80Â h) and initial pollutant concentration (20 to 85Â mg/L) were selected as independent factors; some upper and lower ranges were also monitored for accuracy. In SSFCW, water hyacinth transplanted in two substrate layers, namely zeolite and cockle shell. SSFCW removed 87.7, 81.4, 74.7, and 54.9% of ammonia, phosphate, Cu, and phenol, respectively, at optimum contact time (64.5Â h) and initial pollutant concentration (69.2Â mg/L). Aqueous solution was moved to a surface flow constructed wetland (SFCW) after treating via SSFCW at optimum conditions. In SFCW, Typha was transplanted to a fixed powdered substrate layer, including bentonite, zeolite, and cockle shell. SFCW could develop performance of this combined system and could improve elimination efficacy of the four contaminants to 99.99%. So this combined CW showed a good performance in removing pollutants. Graphical abstract Wetlands arrangement for treating aqueous solution in current study.
Sulphur transformation and deposition in the rhizosphere of Juncus effusus in a laboratory-scale constructed wetland
Wiessner, A.; Kuschk, P.; Jechorek, M.; Seidel, H.; Kaestner, M.
Sulphur cycling and its correlation to removal processes under dynamic redox conditions in the rhizosphere of helophytes in treatment wetlands are poorly understood. Therefore, long-term experiments were performed in laboratory-scale constructed wetlands treating artificial domestic wastewater in order to investigate the dynamics of sulphur compounds, the responses of plants and nitrifying microorganisms under carbon surplus conditions, and the generation of methane. For carbon surplus conditions (carbon:sulphate of 2.8:1) sulphate reduction happened but was repressed, in contrast to unplanted filters mentioned in literature. Doubling the carbon load caused stable and efficient sulphate reduction, rising of pH, increasing enrichment of S 2- and S 0 in pore water, and finally plant death and inhibition of nitrification by sulphide toxicity. The data show a clear correlation of the occurrence of reduced S-species with decreasing C and N removal performance and plant viability in the experimental constructed wetlands. - In an experimental constructed wetland a clear correlation of the occurrence of reduced S-species with decreasing C and N removal performance and plant viability was observed
Performance of a constructed wetland-pond system for treatment and reuse of wastewater from campus buildings.
Ou, Wen-Sheng; Lin, Ying-Feng; Jing, Shuh-Ren; Lin, Hsien-Te
A constructed wetland-pond system consisting of two free-water-surface-flow (FWS) wetland cells, a scenic pond, and a slag filter in series was used for reclamation of septic tank effluent from a campus building. The results show that FWS wetlands effectively removed major pollutants under a hydraulic loading rate between 2.1 and 4.2 cm/d, with average efficiencies ranging from 74 to 78% for total suspended solids, 73 to 88% for 5-day biochemical oxygen demand, 42 to 49% for total nitrogen, 34 to 70% for total phosphorous, 64 to 79% for total coliforms, and 90 to 99.9% for Escherichia coli. After passing through the scenic pond and slag filter, the reclaimed water was used for landscape irrigation. There were a variety of ornamental plants and aquatic animals established in the second FWS cell and scenic pond with good water quality, thus enhancing landscape and ecology amenity in campuses.
Selection of wild macrophytes for use in constructed wetlands for phytoremediation of contaminant mixtures.
Guittonny-Philippe, Anna; Petit, Marie-Eléonore; Masotti, Véronique; Monnier, Yogan; Malleret, Laure; Coulomb, Bruno; Combroux, Isabelle; Baumberger, Teddy; Viglione, Julien; Laffont-Schwob, Isabelle
Constructed wetlands (CWs) offer an alternative to traditional industrial wastewater treatment systems that has been proved to be efficient, cost-effective and environmentally friendly. Most of the time, CWs are planted with proliferative species such as Phragmites australis or with plants originating from nurseries, both representing a risk for the natural biodiversity conservation of aquatic ecosystems located downstream of the CWs. For the removal of metals and organic pollutant mixtures present in industrial effluents, it is necessary to select tolerant plant species that are able to produce a high aboveground biomass and to develop a healthy belowground system. Wild plant species growing in aquatic bodies at industrial outfalls could constitute suitable tolerant species to use in CWs for industrial effluent treatment. To test this hypothesis, we assessed, under laboratory conditions (using an experimental design), the tolerance to mixtures of metals (Al, As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Sn, Zn) or/and organic pollutants (THC, PHE, PYR, LAS) of five European sub-cosmopolitan native macrophytes (Alisma lanceolatum, Carex cuprina, Epilobium hirsutum, Iris pseudacorus and Juncus inflexus) that had been collected in a polluted Mediterranean wetland, after a field study (crossing ecological relevés and analyses of contaminant concentrations in water and sediments). Our results demonstrated that research on phytoremediation of industrial effluents should focus much more on the use of native macrophytes growing at short distances from industrial discharges (such as C. cuprina in this study), and that root/shoot ratio, aerial height and proportion of green leaves are good and cost-effective indicators of plant tolerance to metals and organic pollutant mixtures in laboratory studies. Copyright © 2014 Elsevier Ltd. All rights reserved.
Overview of the state of the art of constructed wetlands for decentralized wastewater management in Brazil.
Machado, A I; Beretta, M; Fragoso, R; Duarte, E
Conventional wastewater treatment plants (WWTPs) commonly require large capital investments as well as operation and maintenance costs. Constructed wetlands (CWs) appear as a cost-effective treatment, since they can remove a broad range of contaminants by a combination of physical, chemical and biological processes with a low cost. Therefore, CWs can be successfully applied for decentralized wastewater treatment in regions with low population density and/or with large land availability as Brazil. The present work provides a review of thirty nine studies developed on CWs implemented in Brazil to remove wastewater contaminants. Brazil current sanitation data is also considered to evaluate the potential role of CWs as decentralized wastewater treatment. Performance of CWs was evaluated according to (i) type of wetland system, (ii) different support matrix (iii) vegetation species and (iv) removal efficiency of chemical oxygen demand (COD), biological oxygen demand (BOD 5 ), nitrogen (N), and phosphorus (P). The reviewed CWs in overall presented good efficiencies, whereas H-CWs achieved the highest removals for P, while the higher results for N were attained on VF-CW and for COD and BOD 5 on HF-CW. Therefore, was concluded that CWs are an interesting solution for decentralized wastewater treatment in Brazil since it has warm temperatures, extensive radiation hours and available land. Additionally, the low percentage of population with access to the sewage network in the North and Northeast regions makes these systems especially suitable. Hence, the further implementation of CW is encouraged by the authors in regions with similar characteristics as Brazil. Copyright © 2016 Elsevier Ltd. All rights reserved.
Flight distance of mosquitoes (Culicidae): A metadata analysis to support the management of barrier zones around rewetted and newly constructed wetlands
Verdonschot, P.F.M.; Besse-Lototskaya, A.A.
Society responds to changes in climate and land use via mitigation measures, including rainwater retention and storage in rewetted and newly constructed wetlands. Humans living close to these wetlands express concerns about future mosquito nuisance situations, and request the necessary distance
Using sorbent waste materials to enhance treatment of micro-point source effluents by constructed wetlands
Green, Verity; Surridge, Ben; Quinton, John; Matthews, Mike
Sorbent materials are widely used in environmental settings as a means of enhancing pollution remediation. A key area of environmental concern is that of water pollution, including the need to treat micro-point sources of wastewater pollution, such as from caravan sites or visitor centres. Constructed wetlands (CWs) represent one means for effective treatment of wastewater from small wastewater producers, in part because they are believed to be economically viable and environmentally sustainable. Constructed wetlands have the potential to remove a range of pollutants found in wastewater, including nitrogen (N), phosphorus (P), biochemical oxygen demand (BOD) and carbon (C), whilst also reducing the total suspended solids (TSS) concentration in effluents. However, there remain particular challenges for P and N removal from wastewater in CWs, as well as the sometimes limited BOD removal within these treatment systems, particularly for micro-point sources of wastewater. It has been hypothesised that the amendment of CWs with sorbent materials can enhance their potential to treat wastewater, particularly through enhancing the removal of N and P. This paper focuses on data from batch and mesocosm studies that were conducted to identify and assess sorbent materials suitable for use within CWs. The aim in using sorbent material was to enhance the combined removal of phosphate (PO4-P) and ammonium (NH4-N). The key selection criteria for the sorbent materials were that they possess effective PO4-P, NH4-N or combined pollutant removal, come from low cost and sustainable sources, have potential for reuse, for example as a fertiliser or soil conditioner, and show limited potential for re-release of adsorbed nutrients. The sorbent materials selected for testing were alum sludge from water treatment works, ochre derived from minewater treatment, biochar derived from various feedstocks, plasterboard and zeolite. The performance of the individual sorbents was assessed through
Potential mining of lithium, beryllium and strontium from oilfield wastewater after enrichment in constructed wetlands and ponds.
Schaller, Jörg; Headley, Tom; Prigent, Stephane; Breuer, Roman
Shortages of resources (chemical elements) used by growing industrial activities require new techniques for their acquisition. A suitable technique could be the use of wetlands for the enrichment of elements from produced water of the oil industry. Oil industries produce very high amounts of water in the course of oil mining. These waters may contain high amounts of rare elements. To our best knowledge nothing is known about the economic potential regarding rare element mining from produced water. Therefore, we estimated the amount of harvestable rare elements remaining in the effluent of a constructed wetland-pond system which is being used to treat and evaporate vast quantities of produced waters. The examined wetland system is located in the desert of the south-eastern Arabian Peninsula. This system manages 95,000 m(3) per day within 350 ha of surface flow wetlands and 350 ha of evaporation ponds and is designed to be used for at least 20 years. We found a strong enrichment of some chemical elements in the water pathway of the system (e.g. lithium up to 896 μg L(-1) and beryllium up to 139 μg L(-1)). For this wetland, lithium and beryllium are the elements with the highest economic potential resulting from a high price and load. It is calculated that after 20 years retention period 131 t of lithium and 57 t of beryllium could be harvested. This technique may also be useful for acquisition of rare earth elements. Other elements (e.g. strontium) with a high calculated load of 4500 tons in 20 years are not efficiently harvestable due to a relatively low market value. In conclusion, wetland treated waters from the oil industry offer a promising new acquisition technique for elements like lithium and beryllium. Copyright © 2014 Elsevier B.V. All rights reserved.
French vertical flow constructed wetlands: a need of a better understanding of the role of the deposit layer.
Molle, Pascal
French vertical flow constructed wetlands, treating directly raw wastewater, have become the main systems implemented for communities under 2,000 population equivalent in France. Like in sludge drying reed beds, an organic deposit layer is formed over time at the top surface of the filter. This deposit layer is a key factor in the performance of the system as it impacts hydraulic, gas transfers, filtration efficiency and water retention time. The paper discusses the role of this deposit layer on the hydraulic and biological behaviour of the system. It presents results from different studies to highlight the positive role of the layer but, as well, the difficulties in modelling this organic layer. As hydraulic, oxygen transfers, and biological activity are interlinked and impacted by the deposit layer, it seems essential to focus on its role (and its quantification) to find new developments of vertical flow constructed wetlands fed with raw wastewater.
A review on the sustainability of constructed wetlands for wastewater treatment: Design and operation.
Wu, Haiming; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Hu, Zhen; Liang, Shuang; Fan, Jinlin; Liu, Hai
Constructed wetlands (CWs) have been used as a green technology to treat various wastewaters for several decades. CWs offer a land-intensive, low-energy, and less-operational-requirements alternative to conventional treatment systems, especially for small communities and remote locations. However, the sustainable operation and successful application of these systems remains a challenge. Hence, this paper aims to provide and inspire sustainable solutions for the performance and application of CWs by giving a comprehensive review of CWs' application and the recent development on their sustainable design and operation for wastewater treatment. Firstly, a brief summary on the definition, classification and application of current CWs was presented. The design parameters and operational conditions of CWs including plant species, substrate types, water depth, hydraulic load, hydraulic retention time and feeding mode related to the sustainable operation for wastewater treatments were then discussed. Lastly, future research on improving the stability and sustainability of CWs were highlighted. Copyright © 2014 Elsevier Ltd. All rights reserved.
Removal of nitrogen and phosphorus from dairy wastewater using constructed wetlands systems operating in batch
Ronaldo Rocha Bastos
Full Text Available This work presents the results of a study conducted for a period of seven months on the effectiveness of constructed wetland systems for the treatment of dairy wastewater aiming at removing, nitrogen and phosphorus. Six experimental systems were assembled with a net volume of 115 L using HDPE tanks, with length/width ratio of 2:1. In three of the systems, gravel 0 was used as substrate, while gravel 0 and sand was used in the three others, in the percentage of 80% and 20%, respectively. The systems were operated in batch cycles of 48 hours, applying 7.5 L of influent per cycle. Four of the experimental units were cultivated, and two kept as controls. The selected species chosen were the macrophytes, Typha domingensis and Hedychium coronarium. The removal efficiency concerning nitrogen compounds showed to be quite promising with values ranging from 29.4 to 73.4%, while phosphorus removal from the beds was lower, reaching efficiencies between 18.61 and 34.3%, considered good values, since the removal of these substances is quite difficult through conventional treatment.
Enhanced Nutrients Removal Using Reeds Straw as Carbon Source in a Laboratory Scale Constructed Wetland
Tong Wang
Full Text Available The low carbon/nitrogen (C/N ratio and high nitrate content characteristics of agricultural runoff restricted the nitrogen removal in constructed wetlands (CWs. To resolve such problems, the economically- and easily-obtained Phragmites Australis (reeds litters were applied and packed in the surface layer of a surface flow CW as external carbon sources. The results demonstrated that the introduction of the reeds straw increased the C concentration as a result of their decomposition during the CW operation, which will help the denitrification in the ensuing operation of an entire 148 days. The total nitrogen (TN and Chemical Oxygen Demand (COD ( in the effluent reached the peak level of 63.2 mg/L and 83 mg/L at the fourth and the second day, respectively. Subsequently, the pollutants in the CW that were filled with straw decreased rapidly and achieved a stable removal after 13 days of operation. Moreover, the present study showed that the N removal efficiency increased with the increase of the hydraulic retention time (HRT. Under the HRT of four days, the CW presented 74.1 ± 6%, 87.4 ± 6% and 56.0 ± 6% removal for TN, NO3-, and TP, respectively.
Performance of a pilot-scale constructed wetland system for treating simulated ash basin water.
Dorman, Lane; Castle, James W; Rodgers, John H
A pilot-scale constructed wetland treatment system (CWTS) was designed and built to decrease the concentration and toxicity of constituents of concern in ash basin water from coal-burning power plants. The CWTS was designed to promote the following treatment processes for metals and metalloids: precipitation as non-bioavailable sulfides, co-precipitation with iron oxyhydroxides, and adsorption onto iron oxides. Concentrations of Zn, Cr, Hg, As, and Se in simulated ash basin water were reduced by the CWTS to less than USEPA-recommended water quality criteria. The removal efficiency (defined as the percent concentration decrease from influent to effluent) was dependent on the influent concentration of the constituent, while the extent of removal (defined as the concentration of a constituent of concern in the CWTS effluent) was independent of the influent concentration. Results from toxicity experiments illustrated that the CWTS eliminated influent toxicity with regard to survival and reduced influent toxicity with regard to reproduction. Reduction in potential for scale formation and biofouling was achieved through treatment of the simulated ash basin water by the pilot-scale CWTS.
Using terrestrial laser scanning in inventorying of a hybrid constructed wetland system.
Obroślak, Radomir; Mazur, Andrzej; Jóźwiakowski, Krzysztof; Dorozhynskyy, Oleksandr; Grzywna, Antoni; Rybicki, Roman; Nieścioruk, Kamil; Król, Żanna; Gabryszuk, Justyna; Gajewska, Magdalena
The goal of this paper was to evaluate the possibility of using terrestrial laser scanning (TLS) for inventorying of a hybrid constructed wetland (CW) wastewater treatment plant. The object under study was a turtle-shaped system built in 2015 in Eastern Poland. Its main purpose is the treatment of wastewater from the Museum and Education Centre of Polesie National Park. The study showed that the CW system had been built in compliance with the technical documentation, as differences between values obtained from the object and those given in the design project (max. ± 20 cm for situation and ±5 cm for elevation) were within the range defined by the legislator. It was also shown that the results were sufficiently precise to be used for as-built surveying of the aboveground elements of the CW system. The TLS technique can also be employed to analyse quantitative changes in object geometry arising during long-term use (e.g. landmass slides or erosion), the identification of which can help in selecting the hot-spots at risk of damage and thus restore the object to its original state as well as prevent new changes.
Modeling the Effect of Plants and Peat on Evapotranspiration in Constructed Wetlands
Florent Chazarenc
Full Text Available Evapotranspiration (ET in constructed wetlands (CWs represents a major factor affecting hydrodynamics and treatment performances. The presence of high ET was shown to improve global treatment performances, however ET is affected by a wide range of parameters including plant development and CWs age. Our study aimed at modelling the effect of plants and peat on ET in CWs; since we hypothesized peat could behave like the presence of accumulated organic matter in old CWs. Treatment performances, hydraulic behaviour, and ET rates were measured in eight 1 m2 CWs mesocosm (1 unplanted, 1 unplanted with peat, 2 planted with Phragmites australis, 2 planted with Typha latifolia and 2 planted with Phragmites australis with peat. Two models were built using first order kinetics to simulate COD and TKN removal with ET as an input. The effect of peat was positive on ET and was related to the better growth conditions it offered to macrophytes. Removal efficiency in pilot units with larger ET was higher for TKN. On average, results show for COD a k20 value of 0.88 d-1 and 0.36 d-1 for TKN. We hypothesized that the main effect of ET was to concentrate effluent, thus enhancing degradation rates.
Estimating greenhouse gas fluxes from constructed wetlands used for water quality improvement
Sukanda Chuersuwan
Full Text Available Methane (CH4 , nitrous oxide (N2O and carbon dioxide (CO2 fluxes were evaluated from constructed wetlands (CWs used to improve domestic wastewater quality. Experiments employed subsurface flow (SF and free water surface flow (FWS CWs planted with Cyperus spp. Results showed seasonal fluctuations of greenhouse gas fluxes. Greenhouse gas fluxes from SF-CWs and FWS-CWS were significantly different (p<0.05 while pollutant removal efficiencies of both CWs were not significantly different. The average CH4 , N2O and CO2 fluxes from SF-CWs were 2.9±3.5, 1.0±1.7, and 15.2±12.3 mg/m2 /hr, respectively, corresponding to the average global warming potential (GWP of 392 mg CO2 equivalents/m2 /hr. For FWS-CWs, the average CH4 , N2O and CO2 fluxes were 5.9±4.8, 1.8±1.0, and 29.6±20.2 mg/m2 /hr, respectively, having an average GWP of 698 mg CO2 equivalents/m2 /hr. Thus, FWS-CWs have a higher GWP than SF-CWs when they were used as a system for domestic water improvement.
Removal efficiencies of constructed wetland and efficacy of plant on treating benzene
Florencio Ballesteros, Jr.
Full Text Available Leaking underground petroleum storage poses human and environmental health risks as it contaminates the soil and the groundwater. Of the many contaminants, benzene – a major constituent of gasoline, is of primary concern. It is an identified carcinogen with a permissible limit set at a low level of 0.005 mg L−1. This poses technical and regulatory challenge to remediation of contaminated sites. Various specialized treatment methods are available, but despite of the high removal efficiencies of sophisticated treatments, the residual level still poses health risks. Thus, additional alternative ways that are cost effective and require minimum technical expertise are necessary, and a constructed wetland (CW is a potential alternative. This study evaluates the performance of a surface flow type CW for the removal of benzene from the contaminated water. It further determines the efficacy of a common reed plant Phragmites karka in treating benzene. Planted and unplanted CW were acclimated with benzene for 16 wk and tested for an 8-d hydraulic retention time at benzene levels of 66 and 45 mg L−1. Results indicate that the planted CW performed better and gave reliable and stable results.
Nitrogen and COD removal from domestic and synthetic wastewater in subsurface-flow constructed wetlands.
Comparisons of the performance of constructed-wetland systems (CWs) for treating domestic wastewater in the laboratory and field may use pathogen-free synthetic wastewater to avoid regulatory health concerns. However, little to no data are available describing the relative treatment efficiencies of CWs to both actual and synthetic domestic wastewaters so as to enable such comparison. To fill this gap, treatment performances with respect to organics (chemical organic demand; COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) and a similar-strength synthetic wastewater under planted and non-planted subsurface-flow CWs are determined. One pair of CWs was planted with cattails in May 2008, whereas the adjacent system was non-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each CWs, and effluent samples were collected and tested for COD and nitrogen species regularly during four different periods over six months. Overall, statistically significant greater removal of COD (-12%) and nitrogen (-5%) occurred from the synthetic as compared with the domestic wastewater from the planted and non-planted CWs. Effluent BOD5/COD ratios from the synthetic wastewater CWs averaged nearly twice that from the domestic wastewater CWs (0.17 vs 0.10), reflecting greater concentrations of readily degraded compounds. That removal fractions were consistent across the mid-range loading rates to the CWs suggests that the synthetic wastewater can be used in testing laboratory CWs with reasonable success in application of their results to the field.
Small scale recirculating vertical flow constructed wetland (RVFCW) for the treatment and reuse of wastewater.
Gross, A; Sklarz, M Y; Yakirevich, A; Soares, M I M
The quantity of freshwater available worldwide is declining, revealing a pressing need for its more efficient use. Moreover, in many developing countries and lightly populated areas, raw wastewater is discarded into the environment posing serious ecological and health problems. Unfortunately, this situation will persist unless low-cost, effective and simple technologies are brought in. The aim of this study is to present such a treatment method, a novel setup which is termed recirculating vertical flow constructed wetland (RVFCW). The RVFCW is composed of two components: (i) a three-layer bed consisting of planted organic soil over an upper layer of filtering media (i.e. tuff or beads) and a lower layer of limestone pebbles, and (ii) a reservoir located beneath the bed. Wastewater flows directly into the plant root zone and trickles down through the three-layer bed into the reservoir, allowing passive aeration. From the reservoir the water is recirculated back to the bed, several times, until the desired purification is achieved. The results obtained show that the RVFCW is an effective and convenient strategy to treat (domestic, grey and agro) wastewater for re-use in irrigation. The system performance is expected to be further improved once current optimization experiments and mathematical modeling studies are concluded. IWA Publishing 2008.
Effect of influent aeration on removal of organic matter from coffee processing wastewater in constructed wetlands.
Rossmann, Maike; Matos, Antonio Teixeira; Abreu, Edgar Carneiro; Silva, Fabyano Fonseca; Borges, Alisson Carraro
The aim of the present study was to evaluate the influence of aeration and vegetation on the removal of organic matter in coffee processing wastewater (CPW) treated in 4 constructed wetlands (CWs), characterized as follows: (i) ryegrass (Lolium multiflorum) cultivated system operating with an aerated influent; (ii) non-cultivated system operating with an aerated influent, (iii) ryegrass cultivated system operating with a non-aerated influent; and (iv) non-cultivated system operating with a non-aerated influent. The lowest average chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of 87, 84 and 73%, respectively, were obtained in the ryegrass cultivated system operating with a non-aerated influent. However, ryegrass cultivation did not influence the removal efficiency of organic matter. Artificial aeration of the CPW, prior to its injection in the CW, did not improve the removal efficiencies of organic matter. On other hand it did contribute to increase the instantaneous rate at which the maximum COD removal efficiency was reached. Although aeration did not result in greater organic matter removal efficiencies, it is important to consider the benefits of aeration on the removal of the other compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.
Determination of the hydraulic residence time of two subsurface-flow constructed wetlands using radiotracers
Debien, Bruno R.
The adoption of constructed wetland systems (CW's) with subsuperficial drainage for sewage treatment is increasingly growing in places with low technological resources and available land. The efficient removal of pollutants depends on the internal flow characteristics in the CW and on its hydraulic residence time (HRT). In the present work 82 Br - a gamma radiation emitter, produced from soluble potassium bromide irradiated in the TRIGA reactor at the Centre for the Development of Nuclear Energy (CDTN) - was used as a pseudo-conservative tracer for the comparative study of aqueous phase flow dynamics in two CW's: one in which plants were grown (WP) whereas the other had no plants (WNP). Experimental hydraulic residence time values were found to be very close to the theoretical one, while dispersion numbers obtained for both CW's were quite small. Besides these measured hydrodynamic parameters, the residence time distribution (RTD) curves of the tracer test and the results of modeling of experimental data also demonstrate the tendency of the units to display a plug flow-like effluent hydraulic transport within their systems, as expected from their designs, considering the large length/width ratio (L/W=8). (author)
Phytoremediation of domestic wastewaters in free water surface constructed wetlands using Azolla pinnata.
Akinbile, Christopher O; Ogunrinde, Temitope A; Che Bt Man, Hasfalina; Aziz, Hamidi Abdul
Two constructed wetlands, one with Azolla pinnata plant (CW1) and the other without (CW2) for treating domestic wastewaters were developed. Fifteen water parameters which include: Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Total Phosphorus (TP), Total Nitrogen (TN), Ammoniacal Nitrogen (NH3N), Turbidity, pH, Electrical Conductivity (EC), Iron (Fe), Magnesium (Mg), Manganese (Mn), and heavy metals such as Lead (Pb) and Zinc (Zn) were analyzed using standard laboratory procedures. The experiments were conducted in two (dry and wet) seasons simultaneously. Results showed considerable reductions in all parameters and metals including Zn in CW1 compared with CW2 in the two seasons considered while Pb and Mn were not detected throughout the study. Zn concentration levels reduced significantly in both seasons just as removal efficiencies of 70.03% and 64.51% were recorded for CW1 while 35.17% and 33.45% were recorded for CW2 in both seasons. There were no significant differences in the removal efficiencies of Fe in both seasons as 99.55%, 59.09%, 88.89%, and 53.56% were recorded in CW1 and CW2 respectively. Azolla pinnata has proved effective in domestic wastewater phytoremediation studies.
Performance assessment of a vertical flow constructed wetland treating unsettled combined sewer overflow.
Pálfy, T G; Gerodolle, M; Gourdon, R; Meyer, D; Troesch, S; Molle, P
The performance of a vertical flow constructed wetland for combined sewer overflow treatment (CSO CW) has been evaluated. The full-scale site has been monitored for 3 years for major pollutants and for two load events for a range of micropollutants (metals, metalloids and polycyclic aromatic hydrocarbons (PAHs)). Performance were predominantly high (97% for total suspended solids (TSS), 80% for chemical oxygen demand (COD), 72% for NH 4 -N), even if several loads were extremely voluminous, pushing the filter to its limits. Two different filter materials (a 4:1 mixture of sand and zeolite and natural pozzolana) showed similar treatment performance. Furthermore, environmental factors were correlated with COD removal efficiency. The greatest influencers of COD removal efficiency were the inlet dissolved COD concentrations and the duration and potential evapotranspiration during inter-event periods. Furthermore, sludge was analysed for quality and a sludge depth map was created. The map, and calculating the changes in sludge volume, helped to understand solid accumulation dynamics.
Treatment and utilization of septic tank effluent using vertical-flow constructed wetlands and vegetable hydroponics.
Cui, Li-Hua; Luo, Shi-Ming; Zhu, Xi-Zhen; Liu, Ying-Hu
Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effluent was treated by vertical flow filter. So the concentration of COD and BOD5 in the treated effluent could meet the quality standard for irrigation water. After that the treated effluent was used for hydroponic cultivation of water spinach and romaine lettuce, the removal efficiencies of the whole system for COD, BOD5, SS, TN and TP were 71.4%, 97.5%, 96.9%, 86.3%, and 87.4%, respectively. And it could meet the integrated wastewater discharge standard for secondary biological treatment plant. It was found that using treated effluent for hydroponic cultivation of vegetables could reduce the nitrate content in vegetables. The removal rates for total bacteria and coliform index by using vertical flow bed system with cinder substrate were 80%-90% and 85%-96%, respectively.
Debien, Bruno R., E-mail: brunordebien@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept de Geografia. Lab. de Geomorfologia; Barreto, Alberto A.; Pinto, Amenonia M.F.; Moreira, Rubens M., E-mail: aab@cdtn.br, E-mail: amfp@cdtn.br, E-mail: rubens@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
The adoption of constructed wetland systems (CW's) with subsuperficial drainage for sewage treatment is increasingly growing in places with low technological resources and available land. The efficient removal of pollutants depends on the internal flow characteristics in the CW and on its hydraulic residence time (HRT). In the present work {sup 82}Br - a gamma radiation emitter, produced from soluble potassium bromide irradiated in the TRIGA reactor at the Centre for the Development of Nuclear Energy (CDTN) - was used as a pseudo-conservative tracer for the comparative study of aqueous phase flow dynamics in two CW's: one in which plants were grown (WP) whereas the other had no plants (WNP). Experimental hydraulic residence time values were found to be very close to the theoretical one, while dispersion numbers obtained for both CW's were quite small. Besides these measured hydrodynamic parameters, the residence time distribution (RTD) curves of the tracer test and the results of modeling of experimental data also demonstrate the tendency of the units to display a plug flow-like effluent hydraulic transport within their systems, as expected from their designs, considering the large length/width ratio (L/W=8). (author)
Potential of Constructed Wetlands for Removal of Antibiotics from Saline Aquaculture Effluents
Maria Bôto
Full Text Available This work aimed to evaluate the potential of constructed wetlands (CWs for removal of antibiotics (enrofloxacin and oxytetracycline and antibiotic resistant bacteria from saline aquaculture wastewaters. Removal of other contaminants (nutrients, organic matter and metals and toxicity reduction and the influence of antibiotics with these processes were evaluated. Thus, nine CWs microcosms, divided into three treatments, were assembled and used to treat wastewater (doped or not with the selected antibiotics between October and December of 2015. Each week treated wastewater was removed and new wastewater (doped or not was introduced in CWs. Results showed >99% of each antibiotic was removed in CWs. After three weeks of adaptation, removal percentages >95% were also obtained for total bacteria and for antibiotic resistant bacteria. Nutrients, organic matter and metal removal percentages in CWs treated wastewater were identical in the absence and in the presence of each antibiotic. Toxicity in treated wastewaters was significantly lower than in initial wastewaters, independently of antibiotics presence. Results showed CWs have a high efficiency for removing enrofloxacin or oxytetracycline as well as antibiotic resistant bacteria from saline aquaculture wastewaters. CWs can also remove other contaminants independently of drug presence, making the aquaculture wastewater possible to be reutilized and/or recirculated.
Observation of Nitrogen and Phosphorus Removals and Accumulations in Surface Flow Constructed Wetland (SFCW
Suntud Sirianuntapiboon
Full Text Available The tropical emergent plant species; Cyperus involucratus, Canna siamensis, Heliconia sp., Hymenocallis littoralis, Typha augustifolia and Thalia dealbata were used to observe nutrients (total phosphorus: TP and total nitrogen: TN removal efficiencies of surface flow constructed wetland (SFCW. The system was operated at different hydraulic retention time (HRT of 1, 3 and 5 days and the average atmospheric temperature of 29.1 ± 4.9oC. The seafood industrial wastewater was employed as the influent. The high biomass production plant species; Cyperus involucratus, Typha augustifolia and Thalia dealbata could generate the high oxidative environment. Amount of N and P accumulations in plant tissue were increased with the increase of plant biomass production. The system did not show any significantly different on N and P accumulations among the tested-emergent plant species. But the amount of accumulated-N and P were increased with the increase of HRT. N accumulations in plant tissue, effluent, sediment and media of the system with the tested-emergent plant species under HRT of 1-5 days were in the range of 2.17-43.80%, 7.91-27.75%, 19.62-36.86% and 14.39-31.88%, respectively. Also, P accumulations were 0.79-17.01%, 20.35-28.37%, 40.96-56.27% and 9.09-20.47%, respectively.
Application of the removal of pollutants from textile industry wastewater in constructed wetlands using fuzzy logic.
Dogdu, Gamze; Yalcuk, Arda; Postalcioglu, Seda
There are more than a hundred textile industries in Turkey that discharge large quantities of dye-rich wastewater, resulting in water pollution. Such effluents must be treated to meet discharge limits imposed by the Water Framework Directive in Turkey. Industrial treatment facilities must be required to monitor operations, keep them cost-effective, prevent operational faults, discharge-limit infringements, and water pollution. This paper proposes the treatment of actual textile wastewater by vertical flow constructed wetland (VFCW) systems operation and monitoring effluent wastewater quality using fuzzy logic with a graphical user interface. The treatment performance of VFCW is investigated in terms of chemical oxygen demand and ammonium nitrogen (NH4-N) content, color, and pH parameters during a 75-day period of operation. A computer program was developed with a fuzzy logic system (a decision- making tool) to graphically present (via a status analysis chart) the quality of treated textile effluent in relation to the Turkish Water Pollution Control Regulation. Fuzzy logic is used in the evaluation of data obtained from the VFCW systems and for notification of critical states exceeding the discharge limits. This creates a warning chart that reports any errors encountered in a reactor during the collection of any sample to the concerned party.
Efficiency of phenol biodegradation by planktonic Pseudomonas pseudoalcaligenes (a constructed wetland isolate) vs. root and gravel biofilm.
Kurzbaum, Eyal; Kirzhner, Felix; Sela, Shlomo; Zimmels, Yoram; Armon, Robert
In the last two decades, constructed wetland systems gained increasing interest in wastewater treatment and as such have been intensively studied around the world. While most of the studies showed excellent removal of various pollutants, the exact contribution, in kinetic terms, of its particular components (such as: root, gravel and water) combined with bacteria is almost nonexistent. In the present study, a phenol degrader bacterium identified as Pseudomonas pseudoalcaligenes was isolated from a constructed wetland, and used in an experimental set-up containing: plants and gravel. Phenol removal rate by planktonic and biofilm bacteria (on sterile Zea mays roots and gravel surfaces) was studied. Specific phenol removal rates revealed significant advantage of planktonic cells (1.04 × 10(-9) mg phenol/CFU/h) compared to root and gravel biofilms: 4.59 × 10(-11)-2.04 × 10(-10) and 8.04 × 10(-11)-4.39 × 10(-10) (mg phenol/CFU/h), respectively. In batch cultures, phenol biodegradation kinetic parameters were determined by biomass growth rates and phenol removal as a function of time. Based on Haldane equation, kinetic constants such as μ(max) = 1.15/h, K(s) = 35.4 mg/L and K(i) = 198.6 mg/L fit well phenol removal by P. pseudoalcaligenes. Although P. pseudoalcaligenes planktonic cells showed the highest phenol removal rate, in constructed wetland systems and especially in those with sub-surface flow, it is expected that surface associated microorganisms (biofilms) will provide a much higher contribution in phenol and other organics removal, due to greater bacterial biomass. Factors affecting the performance of planktonic vs. biofilm bacteria in sub-surface flow constructed wetlands are further discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.
Flood reduction as an ecosystem service of constructed wetlands for combined sewer overflow
Rizzo, A.; Bresciani, R.; Masi, F.; Boano, F.; Revelli, R.; Ridolfi, L.
Urban runoff negatively impacts the receiving streams and different solutions have been proposed in literature to limit the effect of urbanization on the water balance. These solutions suggest to manage urban runoff in order to switch from a post-development river hydrograph (high peak and short duration) back again to a pre-development hydrograph (low peak and high duration). Combined sewer overflows (CSOs) represent severe pollutant sources for receiving streams due to the combination of first flush of roads and sewers and black water conveyed by combined sewer systems. Constructed wetlands for CSO treatment (CSO-CWs) are adopted with increasing frequency for reducing pollutant inputs to streams. Moreover, these systems exhibit the characteristic to behave similarly to ponds, wetlands, and bioretention systems that provide flood mitigation by decreasing the intensity of peak flows. This work aims to show the additional ecosystem service provided by CSO-CWs in term of limitation of the hydraulic impact of CSO on stream hydrograph. A mathematical model is developed to simulate the hydraulic behavior of a real case study situated in Gorla Maggiore (Italy), which includes vertical flow subsurface beds (VF) as first stage and a free water surface bed (FWS) as second stage. The model simulates the unsaturated flow within VF and the accumulation of water on the top of VF and within FWS. Results show a satisfactory lamination performance of the system for both single and up to 5 consecutive flood events, with a peak flow reduction ranging from 52.7% to 95.4%. Withdrawn of flow rate from the river in order to cope with long dry period does not significantly affect the lamination performances. The considered CSO-CW exhibits an excellent lamination efficiency also during more intense floods events, with a peak flow reduction of 86.2% for a CSO event with return period of 10 years. The flow rate frequency density function determined by the CSO-CW is more shifted towards
Efficiency of a constructed wetland for wastewaters treatment Eficiência de um "wetland" construído no tratamento de efluentes
Performance of the constructed wetland systems in pollutants removal from hog wastewater
Wallison da Silva Freitas
Full Text Available The main objective of this work was to evaluate the efficiency of a constructed wetland systems (CWS for pollutants removal, in mono crop and multi crop with three different species of plants, originated from hog wastewater treatment (HW. Therefore, 5 CWS of 24.0 m x 1.1 m x 0.7 m were constructed, sealed with a membrane of polyvinyl chloride (PVC and filled with 0.4 m of small gravel. In CWS1, CWS2 and CWS3 grown to cattail (Typha latifolia L., Alternanthera philoxeroides (Mart. Griseb. and Tifton 85 grass (Cynodon dactylon Pers., respectively. In the bed of CWS4 was planted at 1st third Alternanthera, cattail, in the 2nd third and tifton-85 grass and in the 3rd third of. The CWS5 was not planted and it was used as control. After passing through a filter filled with crushed bagasse of sugar cane, the HW was applied to the CWS in a flow of 0.8 m3 d-1, which corresponded to a hydraulic detention time of 4.8 days. According to the results it was shown that the five CWS(s had statistically nearly the same removal of pollutants, and the average removal efficiency of TSS, COD, BOD and Zn, were 91, 89, 86 and 94%, respectively. Also high removals were obtained concerning the ST, N-total, NH4+ and P-total, with average values of 62, 59, 52 and 50%, respectively. The plants in all planted CWS worked in a similar way maintaining the system efficiency and the non cultivated CWS presented analogous capacity of pollutants removal when compared to the cultivated CWS(s.
Can Artificial Ecosystems Enhance Local Biodiversity? The Case of a Constructed Wetland in a Mediterranean Urban Context
De Martis, Gabriele; Mulas, Bonaria; Malavasi, Veronica; Marignani, Michela
Constructed wetlands (CW) are considered a successful tool to treat wastewater in many countries: their success is mainly assessed observing the rate of pollution reduction, but CW can also contribute to the conservation of ecosystem services. Among the many ecosystem services provided, the biodiversity of CW has received less attention. The EcoSistema Filtro (ESF) of the Molentargius-Saline Regional Natural Park is a constructed wetland situated in Sardinia (Italy), built to filter treated wastewater, increase habitat diversity, and enhance local biodiversity. A floristic survey has been carried out yearly 1 year after the construction of the artificial ecosystem in 2004, observing the modification of the vascular flora composition in time. The flora of the ESF accounted for 54 % of the whole Regional Park's flora; alien species amount to 12 %; taxa of conservation concern are 6 %. Comparing the data in the years, except for the biennium 2006/2007, we observed a continuous increase of species richness, together with an increase of endemics, species of conservation concern, and alien species too. Once the endemics appeared, they remained part of the flora, showing a good persistence in the artificial wetland. Included in a natural park, but trapped in a sprawling and fast growing urban context, this artificial ecosystem provides multiple uses, by preserving and enhancing biodiversity. This is particularly relevant considering that biodiversity can act as a driver of sustainable development in urban areas where most of the world's population lives and comes into direct contact with nature.
Can Artificial Ecosystems Enhance Local Biodiversity? The Case of a Constructed Wetland in a Mediterranean Urban Context.
Constructed wetlands (CW) are considered a successful tool to treat wastewater in many countries: their success is mainly assessed observing the rate of pollution reduction, but CW can also contribute to the conservation of ecosystem services. Among the many ecosystem services provided, the biodiversity of CW has received less attention. The EcoSistema Filtro (ESF) of the Molentargius-Saline Regional Natural Park is a constructed wetland situated in Sardinia (Italy), built to filter treated wastewater, increase habitat diversity, and enhance local biodiversity. A floristic survey has been carried out yearly 1 year after the construction of the artificial ecosystem in 2004, observing the modification of the vascular flora composition in time. The flora of the ESF accounted for 54% of the whole Regional Park's flora; alien species amount to 12%; taxa of conservation concern are 6%. Comparing the data in the years, except for the biennium 2006/2007, we observed a continuous increase of species richness, together with an increase of endemics, species of conservation concern, and alien species too. Once the endemics appeared, they remained part of the flora, showing a good persistence in the artificial wetland. Included in a natural park, but trapped in a sprawling and fast growing urban context, this artificial ecosystem provides multiple uses, by preserving and enhancing biodiversity. This is particularly relevant considering that biodiversity can act as a driver of sustainable development in urban areas where most of the world's population lives and comes into direct contact with nature.
Design of combination biofilter and subsurface constructed wetland-multilayer filtration with vertical flow type using Vetiveria zizanioides (akar wangi)
Astuti, A. D.; Lindu, M.; Yanidar, R.; Faruq, M.
As environmental regulation has become stricter in recent years, there is an increasing concern about the issue of wastewater treatment in urban areas. Senior High School as center of student activity has a potential source to generated domestic wastewater from toilet, bathroom and canteen. Canteen wastewater contains high-organic content that to be treated before discharged. Based on previous research the subsurface constructed wetland-multilayer filtration with vertical flow is an attractive alternative to provide efficient treatment of canteen wastewater. The effluent concentration complied with regulation according to [9]. Due to limited land, addition of preliminary treatment such as the presence of biofilter was found to improve the performance. The aim of this study was to design combination biofilter and subsurface constructed wetland-multilayer filtration with vertical flow type using vetiveria zizanioides (akar wangi) treating canteen wastewater. Vetiveria zizanioides (akar wangi) is used because from previous research, subsurface constructed wetland-multilayer filtration (SCW-MLF) with vertical flow type using vetiveria zizanioides (akar wangi) can be an alternative canteen wastewater treatment that is uncomplicated in technology, low cost in operational and have a beautiful landscape view, besides no odors or insects were presented during the operation.
Back to the Roots: The Integration of a Constructed Wetland into a Recirculating Hatchery - A Case Study
Buři�, Miloš; Bláhovec, Josef; Kouřil, Jan
Aquaculture is currently one of the fastest growing food-producing sectors, accounting for around 50% of the world's food fish. Limited resources, together with climatic change, have stimulated the search for solutions to support and sustain the production of fish as a nutritious food. The integration of a constructed wetland (CW) into a recirculating hatchery (RHS) was evaluated with respect to its economic feasibility and environmental impact. The outcome of eight production cycles showed the potential of CW integration for expanded production without increased operation costs or environmental load. Concretely, the use of constructed wetland allows the rearing about 40% more fish biomass, resulting in higher production and profitability. The low requirements for space, fresh water, and energy enable the establishment of such systems almost anywhere. Constructed wetlands could enhance the productivity of existing small scale facilities, as well as larger systems, to address economic and environmental issues in aquaculture. Such systems have potential to be sustainable in the context of possible future climate change and resource limitations. PMID:25853416
"Wetlands: Water Living Filters?",
Dordio, Ana; Palace, A. J.; Pinto, Ana Paula
Human societies have indirectly used natural wetlands as wastewater discharge sites for many centuries. Observations of the wastewater depuration capacity of natural wetlands have led to a greater understanding of the potential of these ecosystems for pollutant assimilation and have stimulated the development of artificial wetlands systems for treatment of wastewaters from a variety of sources. Constructed wetlands, in contrast to natural wetlands, are human-made systems that are designed, bu...
Nitrous oxide exchanges with the atmosphere of a constructed wetland treating wastewater. Parameters and implications for emission factors
Johansson, A.E.; Svenssom, B.H. [Linkoeing Univ. (Sweden). Dept. of Water and Environmental Studies; Kasimir Klemedtsson, Aa. [Trollhaettan/Uddevalla Univ. College, Trollhaettan (Sweden). Dept. of Informatics and Mathematics; Klemedtsson, L. [Goeteborg Univ. (Sweden). Botanical Inst.
Static chamber measurements of N{sub 2}O fluxes were taken during the 1998 and 1999 growth seasons in a Swedish constructed wetland receiving wastewater. The dominating plant species in different parts of the wetland were Lemna minor L., Typha latifolia L., Spirogyra sp. and Glyceria maxima (Hartm.) and Phalaris arundinacea (L.), respectively. There were large temporal and spatial variations in N{sub 2}O fluxes, which ranged from consumption at -350 to emissions at 1791 {mu}g N{sub 2}O/m{sup 2}/h. The largest positive flux occurred in October 1999 and the lowest in the middle of July 1999. The average N{sub 2}O flux for the two years was 130 {mu}g N{sub 2}O/m{sup 2}/h (SD = 220). No significant differences in N{sub 2}O fluxes were found between the years, even though the two growing seasons differed considerably with respect to both air temperature and precipitation. 15% of the fluxes were negative, showing a consumption of N{sub 2}O. Consumption occurred on a few occasions at most measurement sites and ranged from 1 - 350 {mu}g N{sub 2}O/m{sup 2}/h. 13 - 43% of the variation in N{sub 2}O fluxes was explained by multiple linear regression analysis including principal components. Emission factors were calculated according to IPCC methods from the N{sub 2}O fluxes in the constructed wetland. The calculated emission factors were always lower (0.02 - 0.27%) compared to the default factor provided by the IPCC (0.75%). Thus, direct application of the IPCC default factor may lead to overestimation of N{sub 2}O fluxes from constructed wastewater-treating wetlands.
Occurrence, distribution and bioaccumulation behaviour of hydrophobic organic contaminants in a large-scale constructed wetland in Singapore.
Wang, Qian; Kelly, Barry C
This study involved a field-based investigation to assess the occurrence, distribution and bioaccumulation behaviour of hydrophobic organic contaminants in a large-scale constructed wetland. Samples of raw leachate, water and wetland plants, Typha angustifolia, were collected for chemical analysis. Target contaminants included polychlorinated biphenyls (PCBs), organochlorine pesticides (OCP), as well as several halogenated flame retardants (HFRs) and personal care products (triclosan and synthetic musks). In addition to PCBs and OCPs, synthetic musks, triclosan (TCS) and dechlorane plus stereoisomers (syn- and anti-DPs) were frequently detected. Root concentration factors (log RCF L/kg wet weight) of the various contaminants ranged between 3.0 and 7.9. Leaf concentration factors (log LCF L/kg wet weight) ranged between 2.4 and 8.2. syn- and anti-DPs exhibited the greatest RCF and LCF values. A strong linear relationship was observed between log RCF and octanol-water partition coefficient (log K OW ). Translocation factors (log TFs) were negatively correlated with log K OW . The results demonstrate that more hydrophobic compounds exhibit higher degrees of partitioning into plant roots and are less effectively transported from roots to plant leaves. Methyl triclosan (MTCS) and 2,8-dichlorodibenzo-p-dioxin (DCDD), TCS degradation products, exhibited relatively high concentrations in roots and leaves., highlighting the importance of degradation/biotransformation. The results further suggest that Typha angustifolia in this constructed wetland can aid the removal of hydrophobic organic contaminants present in this landfill leachate. The findings will aid future investigations regarding the fate and bioaccumulation of hydrophobic organic contaminants in constructed wetlands. Copyright © 2017 Elsevier Ltd. All rights reserved.
Feasibility of constructed wetland planted with Leersia hexandra Swartz for removing Cr, Cu and Ni from electroplating wastewater.
You, Shao-Hong; Zhang, Xue-Hong; Liu, Jie; Zhu, Yi-Nian; Gu, Chen
As a low-cost treatment technology for effluent, the constructed wetlands can be applied to remove the heavy metals from wastewater. Leersia hexandra Swartz is a metal-accumulating hygrophyte with great potential to remove heavy metal from water. In this study, two pilot-scale constructed wetlands planted with L. hexandra (CWL) were set up in greenhouse to treat electroplating wastewater containing Cr, Cu and Ni. The treatment performance of CWL under different hydraulic loading rates (HLR) and initial metal concentrations were also evaluated. The results showed that CWL significantly reduced the concentrations of Cr, Cu and Ni in wastewater by 84.4%, 97.1% and 94.3%, respectively. High HLR decreased the removal efficiencies of Cr, Cu and Ni; however, the heavy metal concentrations in effluent met Emission Standard of Pollutants for Electroplating in China (ESPE) at HLR less than 0.3 m3/m2 d. For the influent of 5 mg/L Cr, 10 mg/L Cu and 8 mg/L Ni, effluent concentrations were below maximum allowable concentrations in ESPE, indicating that the removal of Cr, Cu and Ni by CWL was feasible at considerably high influent metal concentrations. Mass balance showed that the primary sink for the retention of contaminants within the constructed wetland system was the sediment, which accounted for 59.5%, 83.5%, and 73.9% of the Cr, Cu and Ni, respectively. The data from the pilot wetlands support the view that CWL could be used to successfully remove Cr, Cu and Ni from electroplating wastewater.
Johansson, A.E.; Svenssom, B.H.; Kasimir Klemedtsson, Aa.; Klemedtsson, L.
Static chamber measurements of N 2 O fluxes were taken during the 1998 and 1999 growth seasons in a Swedish constructed wetland receiving wastewater. The dominating plant species in different parts of the wetland were Lemna minor L., Typha latifolia L., Spirogyra sp. and Glyceria maxima (Hartm.) and Phalaris arundinacea (L.), respectively. There were large temporal and spatial variations in N 2 O fluxes, which ranged from consumption at -350 to emissions at 1791 μg N 2 O/m 2 /h. The largest positive flux occurred in October 1999 and the lowest in the middle of July 1999. The average N 2 O flux for the two years was 130 μg N 2 O/m 2 /h (SD = 220). No significant differences in N 2 O fluxes were found between the years, even though the two growing seasons differed considerably with respect to both air temperature and precipitation. 15% of the fluxes were negative, showing a consumption of N 2 O. Consumption occurred on a few occasions at most measurement sites and ranged from 1 - 350 μg N 2 O/m 2 /h. 13 - 43% of the variation in N 2 O fluxes was explained by multiple linear regression analysis including principal components. Emission factors were calculated according to IPCC methods from the N 2 O fluxes in the constructed wetland. The calculated emission factors were always lower (0.02 - 0.27%) compared to the default factor provided by the IPCC (0.75%). Thus, direct application of the IPCC default factor may lead to overestimation of N 2 O fluxes from constructed wastewater-treating wetlands
Constructed Wetlands for Wastewater Treatment and Wildlife Habitat: 17 Case Studies
This document provides brief descriptions of 17 wetland treatment systems from across the country that are providing significant water quality benefits while demonstrating additional benefits such as wildlife habitat.
Potential mining of lithium, beryllium and strontium from oilfield wastewater after enrichment in constructed wetlands and ponds
Schaller, Jörg [Institute of General Ecology and Environmental Protection, Technische Universität Dresden, D-01062 Dresden (Germany); Bauer Resources, 86529 Schrobenhausen (Germany); Headley, Tom; Prigent, Stephane [Bauer Resources, Constructed Wetland Competence Centre, P.O. Box 1186, P.C. 114 Al Mina, Muscat (Oman); Breuer, Roman [Bauer Resources, 86529 Schrobenhausen (Germany); Bauer Resources, Constructed Wetland Competence Centre, P.O. Box 1186, P.C. 114 Al Mina, Muscat (Oman)
Shortages of resources (chemical elements) used by growing industrial activities require new techniques for their acquisition. A suitable technique could be the use of wetlands for the enrichment of elements from produced water of the oil industry. Oil industries produce very high amounts of water in the course of oil mining. These waters may contain high amounts of rare elements. To our best knowledge nothing is known about the economic potential regarding rare element mining from produced water. Therefore, we estimated the amount of harvestable rare elements remaining in the effluent of a constructed wetland-pond system which is being used to treat and evaporate vast quantities of produced waters. The examined wetland system is located in the desert of the south-eastern Arabian Peninsula. This system manages 95,000 m{sup 3} per day within 350 ha of surface flow wetlands and 350 ha of evaporation ponds and is designed to be used for at least 20 years. We found a strong enrichment of some chemical elements in the water pathway of the system (e.g. lithium up to 896 μg L{sup −1} and beryllium up to 139 μg L{sup −1}). For this wetland, lithium and beryllium are the elements with the highest economic potential resulting from a high price and load. It is calculated that after 20 years retention period 131 t of lithium and 57 t of beryllium could be harvested. This technique may also be useful for acquisition of rare earth elements. Other elements (e.g. strontium) with a high calculated load of 4500 tons in 20 years are not efficiently harvestable due to a relatively low market value. In conclusion, wetland treated waters from the oil industry offer a promising new acquisition technique for elements like lithium and beryllium. - Highlights: • Produced water of oil industry is a source for rare earth elements. • Wetlands can be used for mining of rare earth elements. • A considerable monetary worth can be gained by use of the proposed technique.
Biochar-based constructed wetlands to treat reverse osmosis rejected concentrates in chronic kidney disease endemic areas in Sri Lanka.
Athapattu, B C L; Thalgaspitiya, T W L R; Yasaratne, U L S; Vithanage, Meththika
The objectives were to investigate the potential remedial measures for reverse osmosis (RO) rejected water through constructed wetlands (CWs) with low-cost materials in the media established in chronic kidney disease of unknown etiology (CKDu) prevalent area in Sri Lanka. A pilot-scale surface and subsurface water CWs were established at the Medawachchiya community-based RO water supply unit. Locally available soil, calicut tile and biochar were used in proportions of 81, 16.5 and 2.5% (w/w), respectively, as filter materials in the subsurface. Vetiver grass and Scirpus grossus were selected for subsurface wetland while water lettuce and water hyacinth were chosen for free water surface CWs. Results showed that the CKDu sensitive parameters; total dissolved solids, hardness, total alkalinity and fluoride were reduced considerably (20-85%) and most met desirable levels of stipulated ambient standards. Biochar seemed to play a major role in removing fluoride from the system which may be due to the existing and adsorbed K + , Ca +2 , Mg +2 , etc. on the biochar surface via chemisorption. The least reduction was observed for alkalinity. This study indicated potential purification of aforesaid ions in water which are considerably present in RO rejection. Therefore, the invented bio-geo constructed wetland can be considered as a sustainable, economical and effective option for reducing high concentrations of CKDu sensitive parameters in RO rejected water before discharging into the inland waters.
Peat as Substrate for Small-Scale Constructed Wetlands Polishing Secondary Effluents from Municipal Wastewater Treatment Plant
Meng Jin
Full Text Available With the recent development of constructed wetland technology, it has become a mainstream treatment technology for the mitigation of a variety of wastewaters. This study reports on the treatment performance and pH attenuation capacity of three different configurations of small-scale on-site surface flow constructed wetlands (SFCW: T1 (Peat + Typha latifolia, T2 (T. latifolia alone, and T3 (Peat alone treating secondary effluent from the Amherstview Water Pollution Control Plant (WPCP for two treatment periods (start-up period and operational period. The aim of this study was to compare the nutrients removal efficiencies between the different treatments, as well as to evaluate the effects of substrate and vegetation on the wetland system. For a hydraulic retention time of 2.5 days, the results showed that all treatment systems could attenuate the pH level during both the start-up and operational periods, while significant nutrient removal performance could only be observed during the operational period. Peat was noted to be a better SFCW substrate in promoting the removal of nitrate (NO3-N, total nitrogen (TN, and phosphorus. The addition of T. latifolia further enhanced NO3-N and TN removal efficiencies, but employing T. latifolia alone did not yield effluents that could meet the regulatory discharge limit (1.0 mg/L for phosphorus.
Changes in bacteria composition and efficiency of constructed wetlands under sustained overloads: A modeling experiment.
Boano, F; Rizzo, A; Samsó, R; García, J; Revelli, R; Ridolfi, L
The average organic and hydraulic loads that Constructed Wetlands (CWs) receive are key parameters for their adequate long-term functioning. However, over their lifespan they will inevitably be subject to either episodic or sustained overloadings. Despite that the consequences of sustained overloading are well known (e.g., clogging), the threshold of overloads that these systems can tolerate is difficult to determine. Moreover, the mechanisms that might sustain the buffering capacity (i.e., the reduction of peaks in nutrient load) during overloads are not well understood. The aim of this work is to evaluate the effect of sudden but sustained organic and hydraulic overloads on the general functioning of CWs. To that end, the mathematical model BIO_PORE was used to simulate five different scenarios, based on the features and operation conditions of a pilot CW system: a control simulation representing the average loads; 2 simulations representing +10% and +30% sustained organic overloads; one simulation representing a sustained +30% hydraulic overload; and one simulation with sustained organic and hydraulic overloads of +15% each. Different model outputs (e.g., total bacterial biomass and its spatial distribution, effluent concentrations) were compared among different simulations to evaluate the effects of such operation changes. Results reveal that overloads determine a temporary decrease in removal efficiency before microbial biomass adapts to the new conditions and COD removal efficiency is recovered. Increasing organic overloads cause stronger temporary decreases in COD removal efficiency compared to increasing hydraulic loads. The pace at which clogging develops increases by 10% for each 10% increase on the organic load. Copyright © 2017 Elsevier B.V. All rights reserved.
The use of vertical constructed wetland and ultrasound in aquaponic systems.
Krivograd Klemen�i�, A; Griessler Bulc, T
Treatment performance, fish production, crop plant biomass production, water consumption, and water use efficiency of a pilot aquaponic system for small-scale land-based cyprinid fish farms were evaluated. The system consisted of a 36 m(3) Pond A with an initial carp load of 0.6 kg/m(3); of a treatment chain with a lamellar settler, a roughing filter, a vertical constructed wetland filled with expanded clay and planted with tomatoes; and of a low power ultrasound unit installed in the corner of the pond. The average circulation of the water in the system was 1.2 times per day. Pond A was compared with Pond B of the same dimensions and fish load but with no treatment chain or ultrasound. The treatment chain was efficient in mass removal of total suspended solids , biochemical oxygen demand, chemical oxygen demand, NH4-N, total nitrogen, and total phosphorous (57, 49, 35, 42, 31, and 25 %, respectively). Negative removal of NO3-N, NO2-N, and PO4-P indicated the need for the introduction of additional hydroponic beds in the system. Pond A had markedly lower nutrient concentrations compared with Pond B. Fish body weight increase and specific growth rate in Pond A were higher than in Pond B (102.6 %, 72.1 %; 0.19 %/day, 0.14 %/day, respectively) indicating better rearing conditions in Pond A. Tomato biomass production was high. Water use efficiency was higher in Pond A compared with Pond B (0.31 kg of produced fish/m(3) inflow water and 0.22 kg of produced fish/m(3) inflow water, respectively). The presented aquaponic system could be useful for semi-natural fish farming with fish loads up to 2 kg/m(3).
Application of subsurface vertical flow constructed wetlands to reject water treatment in dairy wastewater treatment plant.
DÄ…browski, Wojciech; Karolinczak, Beata; Gajewska, Magdalena; Wojciechowska, Ewa
The paper presents the effects of applying subsurface vertical flow constructed wetlands (SS VF) for the treatment of reject water generated in the process of aerobic sewage sludge stabilization in the biggest dairy wastewater treatment plant (WWTP) in Poland. Two SS VF beds were built: bed (A) with 0.65 m depth and bed (B) with 1.0 m depth, planted with reeds. Beds were fed with reject water with hydraulic load of 0.1 m d -1 in order to establish the differences in treatment efficiency. During an eight-months research period, a high removal efficiency of predominant pollutants was shown: BOD 5 88.1% (A) and 90.5% (B); COD 84.5% (A) and 87.5% (B); TSS 87.6% (A) and 91.9% (B); TKN 82.4% (A) and 76.5% (B); N-NH 4 + 89.2% (A) and 85.7% (B); TP 30.2% (A) and 40.6% (B). There were not statistically significant differences in the removal efficiencies between bed (B) with 1.0 m depth and bed (A) with 0.65 m depth. The research indicated that SS VF beds could be successfully applied to reject water treatment in dairy WWTPs. The study proved that the use of SS VF beds in full scale in dairy WWTPs would result in a significant decrease in pollutants' load in reject water. In the analyzed case, decreasing the load of ammonia nitrogen was of greatest importance, as it constituted 58% of the total load treated in dairy WWTP and posed a hazard to the stability of the treatment process.
Carbon and nitrogen dynamics and greenhouse gases emissions in constructed wetlands: a review
Jahangir, M. M. R.; Fenton, O.; Gill, L.; Müller, C.; Johnston, P.; Richards, K. G.
The nitrogen (N) removal efficiency of constructed wetlands (CWs) is very inconsistent and does not alone explain if the removed species are reduced by physical attenuation or if they are transformed to other reactive forms (pollution swapping). There are many pathways for the removed N to remain in the system: accumulation in the sediments, leaching to groundwater (nitrate-NO3- and ammonium-NH4+), emission to atmosphere via nitrous oxide- N2O and ammonia and/or conversion to N2 gas and adsorption to sediments. The kinetics of these pathways/processes varies with CWs management and therefore needs to be studied quantitatively for the sustainable use of CWs. For example, the quality of groundwater underlying CWs with regards to the reactive N (Nr) species is largely unknown. Equally, there is a dearth of information on the extent of Nr accumulation in soils and discharge to surface waters and air. Moreover, CWs are rich in dissolved organic carbon (DOC) and produce substantial amounts of CO2 and CH4. These dissolved carbon (C) species drain out to ground and surface waters and emit to the atmosphere. The dynamics of dissolved N2O, CO2 and CH4 in CWs is a key "missing piece" in our understanding of global greenhouse gas budgets. In this review we provide an overview of the current knowledge and discussion about the dynamics of C and N in CWs and their likely impacts on aquatic and atmospheric environments. We suggest that the fate of various N species in CWs and their surface emissions and subsurface drainage fluxes need to be evaluated in a holistic way to better understand their potential for pollution swapping. Research on the process based N removal and balancing the end products into reactive and benign forms are critical to assess environmental impacts of CWs. Thus we strongly suggest that in situ N transformation and fate of the transformation products with regards to pollution swapping requires further detailed examination.
Swine wastewater treatment using vertical subsurface flow constructed wetland planted with Napier grass
Pantip Klomjek
Full Text Available This research aims to investigate the pollutant removal efficiencies in swine wastewater using a vertical subsurface flow constructed wetland (VSF CW planted with two species of Napier grass. The grass productivities were also cultivated and compared in order to provide information for species selection. Twelve treatment units were set up with the VSF CWs planted with Giant Napier grass (Pennisetum purpureum cv. King grass and Dwarf Napier grass (Pennisetum purpureum cv. Mott. with 2 and 5 cm d−1 of hydraulic loading rates (HLR. Comparisons of removal efficiency and grass productivity were analyzed using Duncan's Multiple Range Test and t-test at the significant level 0.05. Both species of Napier grass performed more than 70% of removal efficiency of BOD and TKN. The VSF CW planted with Giant Napier grass at 5 cm d−1 HLR performed the highest BOD removal efficiency of 94 ± 1%, while the 2 cm d−1 HLR removed COD with efficiency of 64 ± 6%. The results also showed the effluent from all treatment units contained averages of BOD, COD, TSS, TKN and pH that followed Thailand's swine wastewater quality standard. Average fresh yields and dry yields were between 4.6 ± 0.4 to 15.2 ± 1.2 and 0.5 ± 0.1 to 2.2 ± 0.1 kg m−2, respectively. The dry yields obtained from four cutting cycles in five months of CW system operation were higher than the ones planted with a traditional method, but declined continuously after each cutting cycle. Both species of Napier grass indicated their suitability to be used in the VSF CW for swine wastewater treatment.
Biological manganese removal from acid mine drainage in constructed wetlands and prototype bioreactors.
Mine drainage waters vary considerably in the range and concentration of heavy metals they contain. Besides iron, manganese is frequently present at elevated concentrations in waters draining both coal and metal mines. Passive treatment systems (aerobic wetlands and compost bioreactors) are designed to remove iron by biologically induced oxidation/precipitation. Manganese, however, is problematic as it does not readily form sulfidic minerals and requires elevated pH (>8) for abiotic oxidation of Mn (II) to insoluble Mn (IV). As a result, manganese removal in passive remediation systems is often less effective than removal of iron. This was found to be the case at the pilot passive treatment plant (PPTP) constructed to treat water draining the former Wheal Jane tin mine in Cornwall, UK, where effective removal of manganese occurred only in one of the three rock filter components of the composite systems over a 1-year period of monitoring. Water in the two rock filter systems where manganese removal was relatively poor was generally system. These differences in water chemistry and manganese removal were due to variable performances in the compost bioreactors that feed the rock filter units in the composite passive systems at Wheal Jane. An alternative approach for removing soluble manganese from mine waters, using fixed bed bioreactors, was developed. Ferromanganese nodules (about 2 cm diameter), collected from an abandoned mine adit in north Wales, were used to inoculate the bioreactors (working volume ca. 700 ml). Following colonization by manganese-oxidizing microbes, the aerated bioreactor catalysed the removal of soluble manganese, via oxidation of Mn (II) and precipitation of the resultant Mn (IV) in the bioreactor, in synthetic media and mine water from the Wheal Jane PPTP. Such an approach has potential application for removing soluble Mn from mine streams and other Mn-contaminated water courses.
Purifying capability, enzyme activity, and nitrification potentials in December in integrated vertical flow constructed wetland with earthworms and different substrates.
Xu, Defu; Gu, Jiaru; Li, Yingxue; Zhang, Yu; Howard, Alan; Guan, Yidong; Li, Jiuhai; Xu, Hui
The response of purifying capability, enzyme activity, nitrification potentials, and total number of bacteria in the rhizosphere in December to wetland plants, substrates, and earthworms was investigated in integrated vertical flow constructed wetlands (IVFCW). The removal efficiency of total nitrogen (TN), NH4-N, chemical oxygen demand (COD), and total phosphorus (TP) was increased when earthworms were added into IVFCW. A significantly average removal efficiency of N in IVFCW that employed river sand as substrate and in IVFCW that employed a mixture of river sand and Qing sand as substrate was not found. However, the average removal efficiency of P was higher in IVFCW with a mixture of river sand and Qing sand as substrate than in IVFCW with river sand as substrate. Invertase activity in December was higher in IVFCW that used a mixture of river sand and Qing sand as substrate than in IVFCW which used only river sand as substrate. However, urease activity, nitrification potential, and total number of bacteria in December was higher in IVFCW that employed river sand as substrate than in IVFCW with a mixture of river sand and Qing sand as substrate. The addition of earthworms into the integrated vertical flow constructed wetland increased the above-ground biomass, enzyme activity (catalase, urease, and invertase), nitrification potentials, and total number of bacteria in December. The above-ground biomass of wetland plants was significantly positively correlated with urease and nitrification potentials (p earthworms into IVFCW increased enzyme activity and nitrification potentials in December, which resulted in improving purifying capability.
Organic Carbon and Disinfection Byproduct Precursor Loads from a Constructed, Non-Tidal Wetland in California's Sacramento–San Joaquin Delta
Jacob A. Fleck
Full Text Available Wetland restoration on peat islands in the Sacramento-San Joaquin Delta will change the quality of island drainage waters entering the Delta, a primary source of drinking water in California. Peat island drainage waters contain high concentrations of dissolved and particulate organic carbon (DOC and POC and organic precursors to drinking water disinfection byproducts, such as trihalomethanes (THMs. We quantified the net loads of DOC, POC, and THM-precursors from a constructed subsidence mitigation wetland on Twitchell Island in the Delta to determine the change in drainage water quality that may be caused by conversion of agricultural land on peat islands to permanently flooded, non-tidal wetlands. Creation of permanently flooded wetlands halts oxidative loss of the peat soils and thereby may mitigate the extensive land-surface subsidence of the islands that threatens levee stability in the Delta. Net loads from the wetland were dominated by DOC flushed from the oxidized shallow peat soil layer by seepage flow out of the wetland. The permanently flooded conditions in the overlying wetland resulted in a gradual evolution to anaerobic conditions in the shallow soil layer and a concomitant decrease in the flow could be minimized by reducing the hydraulic gradient between the wetland and the adjacent drainage ditch. Estimates of net loads from the wetland assuming efflux of surface water only were comparable in magnitude to net loads from nearby agricultural fields, but the wetland and agricultural net loads had opposite seasonal variations. Wetland surface water net loads of DOC, POC, and THM-precursors were lower during the winter months when the greatest amounts of water are available for diversion from the Delta to drinking water reservoirs.
Assessment of a constructed wetland for water recovery and beneficial use of shredded tires in a colonia
Muirhead, D.; Rainwater, K.; Jackson, A.; Urban, L.; Morse, A.
'Full text:' Currently, in many areas of the nation, small communities exist without access to adequate and safe water supplies. Texas, New Mexico, Arizona, and California have several of these communities, called colonias, along the border with Mexico. Many of these communities suffer from high rates of infectious disease due to contaminated sources, unacceptable available water quality, insufficient water quantity, and/or undeveloped infrastructure. Solving these types of problems will require a design born of careful integration of cultural, technical, and regulatory considerations. This project proposes to utilize constructed wetland design as a viable economic solution for a colonia situation that can serve as a test case for more widespread use of this technology. The design will merge technical, social and regulatory aspects of water recycling into one approach. Detailed requirements of the design will include scientific, engineering, and cultural aspects of the system. Based on the social, economic, technical, and environmental information gathered, select up to two on-site water recovery system technologies that are simple, inexpensive, and culturally acceptable. Details of design (plants selected, effluent discharge) are based on interviews with colonia residents to determine their needs. Final site selection is based on poor soils (inappropriate for a leach field), vicinity to schools, and interested families. A comparison of options determined a constructed wetland to be the most viable option. Chipped tires are used as the media, hence, a solid waste problem (local resource) in colonias is converted to a beneficial use. We then analyze and monitor the field performance of the constructed wetland paying special attention to the early TSS discharge of rust particles from steel belted tires. Students are involved from colonia communities in monitoring of systems and environmental data collection. The lessons learned to date are given and construction will
Twenty years experience with constructed wetland systems in Denmark - what did we learn?
Brix, Hans; Schierup, Hans-Henrik; Arias, Carlos Alberto
, the reeds do not increase the hydraulic conductivity of cohesive soils as much as necessary to secure sub-surface flow. Operation needs of soil-based reed beds are low and normally restricted to emptying of the sedimentation tank, cleaning of the distribution system and mowing of the grass around the system...... wetland systems are either compact vertical flow systems which provide good nitrification, willow systems with no discharge or restored wetland systems for nitrate removal. If efficient removal of phosphorus is required, this is achieved by chemical precipitation in the sedimentation tank....
Ecological effects of pipeline construction through deciduous forested wetlands, Midland County, Michigan. Topical report, October 1990--August 1992
Rastorfer, J.R. [Chicago State Univ., IL (United States). Dept. of Biological Sciences; Van Dyke, G.D.; Zellmer, S.D.; Wilkey, P.L. [Argonne National Lab., IL (United States)
This study is designed to record vegetational changes induced by the construction of a large-diameter gas pipeline through deciduous forested wetlands. Two second-growth wetland sites mapped Lenawee soils were selected in Midland County, Michigan: Site 1, a younger stand subjected to recent selective logging, and Site 2, a more mature stand. The collection of ecological data to analyze plant succession on the right-of-way (ROW) and the effects of the developing ROW plant communities on adjacent forest communities was initiated in 1989. Cover class estimates were made for understory and ROW plant species on the basis of 1 {times} 1{minus}m quadrats. Individual stem diameters and species counts were recorded for overstory plants in 10{minus}m quadrats. Although long-term studies have not been completed, firm baseline data were established for comparative analyses with future sampling. Current data indicate that vegetation became well-established on the ROW within one year and subsequently increased in coverage. About 65% of the species were wetland indicators, and the dominants included seeded and natural invading species; nevertheless, some elements of the original flora regenerated and persist. The plants of the ecotone understories of both sites changed from their original composition as a result of the installation of the gas pipeline. Although some forest species persist at both sites, the ecotone of Site I was influenced more by the seeded species, whereas the natural invaders were more important at Site 2.
Application of constructed wetlands for wastewater treatment in developing countries--a review of recent developments (2000-2013).
Zhang, Dong Qing; Jinadasa, K B S N; Gersberg, Richard M; Liu, Yu; Ng, Wun Jern; Tan, Soon Keat
Inadequate access to clean water and sanitation has become one of the most pervasive problems afflicting people throughout the developing world. Replication of centralized water-, energy- and cost-intensive technologies has proved ineffective in resolving the complex water-related problems resulting from rapid urbanization in the developing countries. Instead constructed wetlands (CWs) have emerged and become a viable option for wastewater treatment, and are currently being recognized as attractive alternatives to conventional wastewater treatment methods. The primary objective of this review is to present a comprehensive overview of the diverse range of practice, applications and researches of CW systems for removing various contaminants from wastewater in developing countries, placing them in the overall context of the need for low-cost and sustainable wastewater treatment systems. Emphasis of this review is placed on the treatment performance of various types of CWs including: (i) free water surface flow CW; (ii) subsurface flow CW; (iii) hybrid systems; and, (iv) floating treatment wetland. The impacts of different wetland design and pertinent operational variables (e.g., hydraulic loading rate, vegetation species, physical configurations, and seasonal variation) on contaminant removal in CW systems are also summarized and highlighted. Finally, the cost and land requirements for CW systems are critically evaluated. Copyright © 2014 Elsevier Ltd. All rights reserved.
Enhancement of Nutrient Removal in a Hybrid Constructed Wetland Utilizing an Electric Fan Air Blower with Renewable Energy of Solar and Wind Power
Dong Jin Lee
Full Text Available The sewage treatment efficiency of hybrid constructed wetlands (CWs was evaluated under different ventilation methods. The removal efficiencies of biochemical oxygen demand (BOD, total nitrogen (TN, and total phosphorus (TP in the vertical flow- (VF- horizontal flow (HF CWs using an electric fan air blower by the renewable energy of solar and wind power were higher than those by natural ventilation, excluding only suspended solids (SS. The TN treatment efficiency in the CW using the air blower especially increased rapidly by 16.6% in comparison with the CW employing natural ventilation, since the VF bed provided suitable conditions (aerobic for nitrification to occur. The average removal efficiencies of BOD, SS, TN, and TP in the effluent were 98.8, 97.4, 58.0, and 48.3% in the CW using an electric fan air blower, respectively. The treatment performance of the CWs under different ventilation methods was assessed, showing TN in the CW using an electric fan air blower to be reduced by 57.5~58.6% for inlet TN loading, whereas reduction by 19.0~53.3% was observed in the CW with natural ventilation. Therefore, to increase the removal of nutrients in CWs, an improved ventilation system, providing ventilation via an electric fan air blower with the renewable energy, is recommended.
The Effect of the Hydraulic Retention Time on the Performance of an Ecological Wastewater Treatment System: An Anaerobic Filter with a Constructed Wetland
María L. Merino-Solís
Full Text Available This work assesses the performance of a municipal pilot wastewater treatment system employing an up-flow anaerobic filter (UAF followed by a horizontal subsurface constructed wetland (HSSCW. This pilot scale demonstration project was implemented in a zone with subtropical climate in order to protect Lake Chapala from wastewater loads that are discharged by small communities in the Lake's vicinity. The filters were filled with tezontle as the media for biofilm support and the HSSCW was planted with two ornamental plants species, Canna hybrids and Strelitzia reginae. The experiment evaluated three hydraulic retention times (HRT of 18, 28 and 38 h in the UAF, which corresponds to two, three and four days in HSSCW over 66 weeks. The mean efficiencies found for the complete system were 80% and 90% of BOD, 80% and 86% of COD, 30% and 33% of Ntot and between 24% and 44% of Ptot. It was possible to remove almost 80% of organic matter in 18 h in the UAF while the HSSCW reached 30% of removal for Ntot in a HRT of three days. As expected, the UAF was responsible for removing most of the organic matter and the HSSCW removed most of the nitrogen.
Evaluation of Organic Matter Removal Efficiency and Microbial Enzyme Activity in Vertical-Flow Constructed Wetland Systems
Qiaoling Xu
Full Text Available In this study, enzyme activities and their relationships to organics purification were investigated in three different vertical flow constructed wetlands, namely system A (planting Pennisetum sinese Roxb, system B (planting Pennisetum purpureum Schum., and system C (no plant. These three wetland systems were fed with simulation domestic sewage at an influent flow rate of 20 cm/day. The results showed that the final removal efficiency of Chemical Oxygen Demand (COD in these three systems was 87%, 85% and 63%, respectively. Planting Pennisetum sinese Roxb and Pennisetum purpureum Schum. could improve the amount of adsorption and interception for organic matter in the substrate, and the amount of interception of organic matter in planting the Pennisetum sinese Roxb system was higher than that in planting the Pennisetum purpureum Schum. system. The activities of enzymes (urease, phosphatase and cellulase in systems A and B were higher than those in system C, and these enzyme activities in the top layer (0–30 cm were significantly higher than in the other layers. The correlations between the activities of urease, phosphatase, cellulase and the COD removal rates were R = 0.815, 0.961 and 0.973, respectively. It suggests that using Pennisetum sinese Roxb and Pennisetum purpureum Schum. as wetland plants could promote organics removal, and the activities of urease, phosphatase and cellulase in those three systems were important indicators for COD purification from wastewater. In addition, 0–30 cm was the main function layer. This study could provide a theoretical basis for COD removal in the wetland system and supply new plant materials for selection.
Application of constructed wetlands to the treatment of leachates from a municipal solid waste landfill in Ibadan, Nigeria.
Aluko, Olufemi Oludare; Sridhar, M K C
Leachates are wastewater generated principally from landfills and solid waste disposal sites. Leachates emanating from municipal wastes are a major source of surface and groundwater pollution worldwide. Globally, leachates have been implicated in low yield of farm produce, developmental anomalies, low birth weights, leukemia incidence, and other cancers in communities around the site. They have also been implicated in hazards to the environment, loss of biodiversity, and contamination of water sources. At Aba-Eku in Nigeria, leachates are being discharged into the Omi Stream without treatment. A study was conducted on a method of leachate treatment that passes the leachate through constructed wetlands using Ipomoea aquatica (Forsk), a locally available plant found close to the landfill site. The aim of the study was to evolve a sustainable and cost-effective method of treatment whose effluents can be discharged into the Omi Stream with no or minimal impact. The study was descriptive and analytical in design. Samples were collected and analyzed with standard methods for pH, suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia, nitrate, and trace metals. Raw leachates were turbid and amber in color and contained suspended solids (197.5 mg/L), ammonia (610.9 mg/L), lead (1.64 mg/L), iron (198.10 mg/L), and manganese (23.20 mg/L). When the leachates were passed through the constructed wetland with eight hours' detention time, effluents showed significant reductions in suspended solids (81.01 percent), BOD (86.03 percent), and ammonia (97.77 percent). The study shows that a constructed wetland is a feasible tool for the treatment of leachates before their disposal into the environment in Nigeria and can help safeguard environmental quality.
Wetland assessment of the effects of construction and operation of a depleted uranium hexafluoride conversion facility at the Portsmouth, Ohio, site
Van Lonkhuyzen, R.
The U.S. Department of Energy (DOE) Depleted Uranium Hexafluoride (DUF 6 ) Management Program evaluated alternatives for managing its inventory of DUF 6 and issued the ''Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted Uranium Hexafluoride'' (DUF 6 PEIS) in April 1999 (DOE 1999). The DUF 6 inventory is stored in cylinders at three DOE sites: Paducah, Kentucky; Portsmouth, Ohio; and East Tennessee Technology Park (ETTP), near Oak Ridge, Tennessee. In the Record of Decision for the DUF 6 PEIS, DOE stated its decision to promptly convert the DUF 6 inventory to a more stable chemical form. Subsequently, the U.S. Congress passed, and the President signed, the ''2002 Supplemental Appropriations Act for Further Recovery from and Response to Terrorist Attacks on the United States'' (Public Law No. 107-206). This law stipulated in part that, within 30 days of enactment, DOE must award a contract for the design, construction, and operation of a DUF 6 conversion plant at the Department's Paducah, Kentucky, and Portsmouth, Ohio, sites, and for the shipment of DUF 6 cylinders stored at ETTP to the Portsmouth site for conversion. This wetland assessment has been prepared by DOE, pursuant to Executive Order 11990 (''Protection of Wetlands'') and DOE regulations for implementing this Executive Order as set forth in Title 10, Part 1022, of the ''Code of Federal Regulations'' (10 CFR Part 1022 [Compliance with Floodplain and Wetland Environmental Review Requirements]), to evaluate potential impacts to wetlands from the construction and operation of a conversion facility at the DOE Portsmouth site. Approximately 0.02 acre (0.009 ha) of a 0.08-acre (0.03-ha) palustrine emergent wetland would likely be eliminated by direct placement of fill material during facility construction at Location A. Portions of this wetland that are not filled may be indirectly affected by an altered hydrologic regime because of the
Carbon, Nitrogen and Phosphorus Tranformations are Related to Age of a Constructe Wetland
Zemanová, K.; Picek, T.; Dušek, Jiří; Edwards, K.; Šantrů�ková, H.
Ro�. 207, 1-4 (2010), s. 39-48 ISSN 0049-6979 Institutional research plan: CEZ:AV0Z60870520 Keywords : constucted wetlands * carbon * nitrogen * phosphorus * mineralization * microbial processes * greenhouse gasses Subject RIV: EH - Ecology, Behaviour Impact factor: 1.765, year: 2010 http://www.springerlink.com/content/l3g88621603934r0/
Jiangsu coastal highland reclamation and its wetland ecological construction-a case analysis of the Tiaozini reclamation project
Yu, Meixiu; Xu, Xianghong
,developing more suitable water bird habitats by reserving natural ecological wetland and restoring affected wetland. The TRP is attempting to be built as an ecological cultivation demonstration integrated with ecological restoration, science research and education, and ecological leisure respectively. To better protecting and restoring tidal wetland, and for sustainable utilization and management of wetland resource, Jiangsu coast development group CO., Ltd (it is in charge of the TRP reclamation and development), Hohai University and Deltares signed a triple cooperation strategic framework agreement, co-building the Jiangsu Province coastal development and ecological construction engineering center. Besides, routine surveys in ecological, hydrological, topographic data in/around the TRP are also carrying out as well as the ecological compensations.
Construction of horizontal stratum landform-like composite foams and their methyl orange adsorption capacity
Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing
Highlights: • CS/REC/CNTs composite foams were prepared by unidirectional freeze-casting. • Horizontal stratum landform-like structure was successful built up in foam. • The addition of REC and CNTs promoted the mechanical properties of foam. • The introduction of REC and CNTs enhanced the adsorption capacity of foam on dye. - Abstract: Chitosan (CS)/rectorite (REC)/carbon nanotubes (CNTs) composite foams with good mechanical properties were successfully fabricated by unidirectional freeze-casting technique. The morphology of the foam showed the well-ordered porous three-dimensional layers and horizontal stratum landform-like structure. The holes on the layers looked like the wings of butterfly. Additionally, the X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results indicated the successful addition of CNTs and REC. The intercalated REC with CS chains was confirmed by small-angle X-ray diffraction. The surface structure of the foams was also analyzed by Raman spectroscopy. The adsorption experiments showed that when the mass ratio of CS to REC was 10:1 and CNTs content was 20%, the composite foam performed best in adsorbing low concentration methyl orange, and the largest adsorption capacity was 41.65 mg/g.
Chen, Jiajia; Shi, Xiaowen; Zhan, Yingfei; Qiu, Xiaodan; Du, Yumin; Deng, Hongbing, E-mail: hbdeng@whu.edu.cn
Penurunan Logam Timbal (Pb pada Limbah Cair TPA Piyungan Yogyakarta dengan Constructed Wetlands Menggunakan Tumbuhan Eceng Gondok (Eichornia Crassipes
Eko Siswoyo
Full Text Available Salah satu permasalahan lingkungan yang ditimbulkan dari adanya lindi di TPA Piyungan yaitu pencemaran pada badan air, sungai dan air tanah. Untuk mengatasi permasalahan ini salah satunya dengan sistem Constructed Wetlands dengan menggunakan tumbuhah eceng gondok. Tujuan dari penelitian ini adalah untuk mengetahui tingkat penurunan konsentrasi Timbal (Pb yang terdapat dalam limbah cair TPA Piyungan dengan Constructed Wetlands menggunakan tumbuhan eceng gondok dan untuk mengetahui seberapa besar kapasitas serapan tumbuhan eceng gondok terhadap kandungan Timbal (Pb dalam limbah cair TPA Piyungan.Dalam penelitian ini digunakan reaktor yang terbuat dari kayu yang dilapisi plastik dengan ukuran 0,5 m x 1,0 m. Setiap reaktor diberi media tanah 5 cm, dan diberi tumbuhan sebanyak 14 buah. Reaktor tersebut diberi perlakuan dengan konsentrasi limbah yang bervariasi (100%, 75%, 50%, 25%, dan 0%, dan waktu pengambilan sampel (0, 3, 6, 9, 12 hari. Dengan menggunakan metode SSA (Spektrofotometri Serapan Atom.Berdasarkan pengujian diperoleh bahwa penurunan logam Pb pada limbah cair TPA Piyungan hari ke- 12, yaitu sebesar 0.0501mg/L pada konsentrasi 100%, 0.0295mg/L pada konsentrasi 75%, 0.0267mg/L pada konsentrasi 50% dan 0.0041 mg/L pada konsentrasi 25%.
Spatiotemporal and species variations in prokaryotic communities associated with sediments from surface-flow constructed wetlands for treating swine wastewater.
Jia, Fen; Lai, Cui; Chen, Liang; Zeng, Guangming; Huang, Danlian; Liu, Feng; Li, Xi; Luo, Pei; Wu, Jinshui; Qin, Lei; Zhang, Chen; Cheng, Min; Xu, Piao
Microorganisms are the main mechanisms of pollutants removals in constructed wetlands (CWs) used for wastewater treatment. However, the different biological processes and variations of prokaryotic community in CWs remain poorly understood. In this study, we applied a high-throughput sequencing technique to investigate the prokaryotic communities associated with sediments from pilot-scale surface-flow constructed wetlands (SFCWs) treating swine wastewater (SW) of varying strengths. Our results revealed that highly diverse prokaryotic communities were present in the SFCWs, with Proteobacteria (16.44-44.44%), Acidobacteria (3.25-24.40%), and Chloroflexi (5.77-14.43%) being the major phyla, and Nitrospira (4.14-12.02%), the most dominant genus. The prokaryotic communities in the sediments varied greatly with location and season, which markedly altered the microenvironmental conditions. Principal co-ordinates analysis indicated that SW strength significantly influenced the community structure in sediments of the SFCWs, and canonical correspondence analysis illustrated that the shifts in prokaryotic communities were strongly related to NO 3 - -N and TN in winter; and in summer with NH 4 + N, NO 3 - -N, NO 2 - -N, TN, TP, SOM, and pH. In conclusion, the use of high-throughput sequencing greatly enhanced our understanding of prokaryotic communities with different functional groups in SFCWs. Copyright © 2017 Elsevier Ltd. All rights reserved.
Evaluation of the seasonal performance of a water reclamation pond-constructed wetland system for removing emerging contaminants.
Matamoros, Víctor; Salvadó, Victòria
The capacity of a full-scale reclamation pond-constructed wetland (CW) system to eliminate 27 emerging contaminants (i.e. pharmaceuticals, sunscreen compounds, fragrances, antiseptics, fire retardants, pesticides, and plasticizers) and the seasonal occurrence of these contaminants is studied. The compounds with the highest concentrations in the secondary effluent are diclofenac, caffeine, ketoprofen, and carbamazepine. The results show that the constructed wetland (61%) removes emerging contaminants significantly more efficiently than the pond (51%), presumably due to the presence of plants (Phragmites and Thypa) as well as the higher hydraulic residence time (HRT) in the CW. A greater seasonal trend to the efficient removal of these compounds is observed in the pond than in the CW. The overall mass removal efficiency of each individual compound ranged from 27% to 93% (71% on average), which is comparable to reported data in advanced treatments (photo-fenton and membrane filtration). The seasonal average content of emerging contaminants in the river water (2488 ng L(-1)) next to the water reclamation plant is found to be higher than the content in the final reclaimed water (1490 ng L(-1)), suggesting that the chemical quality of the reclaimed water is better than available surface waters. Copyright © 2011 Elsevier Ltd. All rights reserved.
Performance assessment and microbial diversity of two pilot scale multi-stage sub-surface flow constructed wetland systems.
Babatunde, A O; Miranda-CasoLuengo, Raul; Imtiaz, Mehreen; Zhao, Y Q; Meijer, Wim G
This study assessed the performance and diversity of microbial communities in multi-stage sub-surface flow constructed wetland systems (CWs). Our aim was to assess the impact of configuration on treatment performance and microbial diversity in the systems. Results indicate that at loading rates up to 100gBOD5/(m(2)·day), similar treatment performances can be achieved using either a 3 or 4 stage configuration. In the case of phosphorus (P), the impact of configuration was less obvious and a minimum of 80% P removal can be expected for loadings up to 10gP/(m(2)·day) based on the performance results obtained within the first 16months of operation. Microbial analysis showed an increased bacterial diversity in stage four compared to the first stage. These results indicate that the design and configuration of multi-stage constructed wetland systems may have an impact on the treatment performance and the composition of the microbial community in the systems, and such knowledge can be used to improve their design and performance. Copyright © 2016. Published by Elsevier B.V.
Optimization of operating parameters of hybrid vertical down-flow constructed wetland systems for domestic sewerage treatment.
Huang, Zhujian; Zhang, Xianning; Cui, Lihua; Yu, Guangwei
In this work, three hybrid vertical down-flow constructed wetland (HVDF-CW) systems with different compound substrates were fed with domestic sewage and their pollutants removal performance under different hydraulic loading and step-feeding ratio was investigated. The results showed that the hydraulic loading and step-feeding ratio were two crucial factors determining the removal efficiency of most pollutants, while substrate types only significantly affected the removal of COD and NH4(+)-N. Generally, the lower the hydraulic loading, the better removal efficiency of all contaminants, except for TN. By contrast, the increase of step-feeding ratio would slightly reduce the removal rate of ammonium and TP but obviously promoted the TN removal. Therefore, the optimal operation of this CWs could be achieved with low hydraulic loading combined with 50% of step-feeding ratio when TN removal is the priority, whereas medium or low hydraulic loading without step-feeding would be suitable when TN removal is not taken into consideration. The obtained results in this study can provide us with a guideline for design and optimization of hybrid vertical flow constructed wetland systems to improve the pollutants removal from domestic sewage. Copyright © 2016 Elsevier Ltd. All rights reserved.
Nitrogen and chemical oxygen demand removal from septic tank wastewater in subsurface flow constructed wetlands: substrate (cation exchange capacity) effects.
Collison, Robert S; Grismer, Mark E
The current article focuses on chemical oxygen demand (COD) and nitrogen (ammonium and nitrate) removal performance from synthetic human wastewater as affected by different substrate rocks having a range of porosities and cation exchange capacities (CECs). The aggregates included lava rock, lightweight expanded shale, meta-basalt (control), and zeolite. The first three had CECs of 1 to 4 mequiv/100 gm, whereas the zeolite CEC was much greater (-80 mequiv/100 gm). Synthetic wastewater was gravity fed to each constructed wetland system, resulting in a 4-day retention time. Effluent samples were collected, and COD and nitrogen species concentrations measured regularly during four time periods from November 2008 through June 2009. Chemical oxygen demand and nitrogen removal fractions were not significantly different between the field and laboratory constructed wetland systems when corrected for temperature. Similarly, overall COD and nitrogen removal fractions were practically the same for the aggregate substrates. The important difference between aggregate effects was the zeolite's ammonia removal process, which was primarily by adsorption. The resulting single-stage nitrogen removal process may be an alternative to nitrification and denitrification that may realize significant cost savings in practice.
Solid respirometry to characterize nitrification kinetics: a better insight for modelling nitrogen conversion in vertical flow constructed wetlands.
Morvannou, Ania; Choubert, Jean-Marc; Vanclooster, Marnik; Molle, Pascal
We developed an original method to measure nitrification rates at different depths of a vertical flow constructed wetland (VFCW) with variable contents of organic matter (sludge, colonized gravel). The method was adapted for organic matter sampled in constructed wetland (sludge, colonized gravel) operated under partially saturated conditions and is based on respirometric principles. Measurements were performed on a reactor, containing a mixture of organic matter (sludge, colonized gravel) mixed with a bulking agent (wood), on which an ammonium-containing liquid was applied. The oxygen demand was determined from analysing oxygen concentration of the gas passing through the reactor with an on-line analyzer equipped with a paramagnetic detector. Within this paper we present the overall methodology, the factors influencing the measurement (sample volume, nature and concentration of the applied liquid, number of successive applications), and the robustness of the method. The combination of this new method with a mass balance approach also allowed determining the concentration and maximum growth rate of the autotrophic biomass in different layers of a VFCW. These latter parameters are essential inputs for the VFCW plant modelling. Copyright © 2011 Elsevier Ltd. All rights reserved.
EFISIENSI CONSTRUCTION WETLAND TYPHA SP. SEBAGAI PENGOLAH AIR LIMPASAN JALAN RAYA SECARA ALAMI
Rudatin Windraswara
Full Text Available Penelitian ini bersifat desain eksperimental pada skala laboratorium untuk mengetahui kemampuan Typha latifolia. sebagai tanaman wetland dalam mereduksi BOD dan COD yang berasal polutan air limpasan jalan raya sebagai bagian dari sistem drainase yang berkelanjutan. Sampel dalam penelitian ini adalah air limpasan jalan yang berasal dari air hujan yang kemudian masuk ke saluran pengumpul (drainase jalan. Habitat wetland disimulasikan menggunakan kolom dengan tabung yang memiliki volume kosong 20 liter. Susunan tabung adalah sebagai berikut; tanaman wetland, air, pasir dan batu kerikil. Satu tabung lagi akan berlaku sebagai kontrol dengan susunan yang sama tanpa tanaman wetland. Desain tabung memiliki spesifikasi sebagai berikut bahan acrylic dengan ukuran diameter 9,7 cm, tinggi 40 cm, volume 20 liter, media pasir setinggi 10 cm, kerikil 15 cm, kemudian diisi air setinggi 15 cm dari batas kerikil. Nilai BOD dari sampel kontrol setelah hari ke-3 menjadi 87 mg/l dari nilai semula 104 mg/l sedangkan nilai BOD dari sampel uji setelah hari ke-3 menjadi 44 mg/l dari nilai semula 104 mg/l. Hasil ini menunjukkan tanaman tersebut mampu menghilangkan nilai BOD sebesar 65% atau BOD removal sebesar 65%. Nilai COD dari sampel kontrol setelah hari ke-3 menjadi 309 mg/l dari nilai semula 210 mg/l sedangkan nilai COD dari sampel uji setelah hari ke-3 menjadi 87 mg/l dari nilai semula 210 mg/l. Hasil ini menunjukkan tanaman Typha latifolia mampu menghilangkan nilai COD sebesar 58,6% atau COD removal sebesar 58,6%. Kedua parameter tersebut telah sesuai dengan baku mutu Kepmen LH no 112 tahun 2003 dan Kepmen LH no 51 tahun 1999.
Effect of plants in constructed wetlands for organic carbon and nutrient removal: a review of experimental factors contributing to higher impact and suggestions for future guidelines.
Jesus, João M; Danko, Anthony S; Fiúza, António; Borges, Maria-Teresa
Constructed wetland is a proven technology for water pollution removal, but process mechanisms and their respective contribution are not fully understood. The present review details the effect of plants on removal efficiency of constructed wetlands by focusing on literature that includes experiments with unplanted controls for organic carbon and nutrient (N and P) removal. The contribution of plant direct uptake is also assessed. Although it was found that several studies, mostly at laboratory or pilot scales, showed no statistical differences between planted and unplanted controls, some factors were found that help maximize the effect of plants. This study intends to contribute to a better understanding of the significance of the effect of plants in a constructed wetland, as well as to suggest a set of experimental guidelines in this field.
The Influence of the Ratio of Nitrate to Ammonium Nitrogen on Nitrogen Removal in the Economical Growth of Vegetation in Hybrid Constructed Wetlands
Haq Nawaz Abbasi
Full Text Available Growing vegetables economically in the use of constructed wetland for wastewater treatment can play a role in overcoming water and food scarcity. Allium porrum L., Solanum melongena L., Ipomoea aquatica Forsk., and Capsicum annuum L. plants were selected to grow in hybrid constructed wetland (CW under natural conditions. The impact of the ratio of nitrate to ammonium nitrogen on ammonium and nitrate nitrogen removal and on total nitrogen were studied in wastewater. Constructed wetland planted with Ipomoea aquatica Forsk. and Solanum melongena L. showed higher removal efficiency for ammonium nitrogen under higher ammonium concentration, whereas Allium porrum L.-planted CW showed higher nitrate nitrogen removal when NO3–N concentration was high in wastewater. Capsicum annuum L.-planted CW showed little efficiency for both nitrogen sources compared to other vegetables.
Efficiency of sewage treatment with septic tanks followed by constructed wetlands with different support materials
Delvio Sandri
Full Text Available This study seeks to assess the efficiency of a sewage treatment plant comprised of three compartmentalized septic tanks installed in series followed by three parallel wetlands and seeded with species Typha sp. with subsurface flow, filled with support material of natural gravel, gravel # 2 and washed gravel, respectively. The station treats sewage generated at Unity University for Science and Technology, State University of Goiás – UnUCET/UEG. A total of 20 sewage samples were collected in order to evaluate treatment efficiency from November to December 2010 and March to April 2011. The points of analysis were at the input of the first tank (raw sewage, the output of the third septic tank and the outputs of each of the three wetlands. The total removal efficiencies were: 65.40% for chemical oxygen demand; 79.01% for biochemical oxygen demand; 59.79% for total solids; 87.12% for the total suspended solids; 92.00% for total coliforms; 95.71% for E. coli and 82.54% for turbidity. The system was effective for the treatment of sewage, within the current legislative parameters for pH, turbidity, total solids and biochemical oxygen demand. No significant difference was observed between the three different means of support, suggesting that gravel, natural gravel and washed gravel may potentially be used to fill wetlands.
Phytoremediation potential of poplar and willow species in small scale constructed wetland for boron removal.
Yıldırım, Kubilay; Kasım, Gözde Çıtır
Boron (B) pollution is an expanding environmental problem throughout the world due to intensive mining practices and extensive usage of B in agricultural chemicals and industrial products in recent years. The purpose of this study was to investigate B removal performance of four poplar and four willow species in small scale Constructed Wetland (CW). Rooted cuttings of tested species were treated with simulated wastewater having five elevated B concentrations (0.5, 5, 10, 20 and 40 ppm). All the tested species could resist up to 20 ppm wastewater B supply and could regrow from their roots in the soil having maximum 15 mg/kg B content. The result of the study indicated that 65% ± 5.3 of B was removed from the wastewater in 5 ppm B treatment while the same efficiency decreased to 45% ± 4.6 at 40 ppm B supply. The average effect of sediment on B removal was found to be approximately 20% for all B treatments while the remaining part of the loaded B was removed from the CW within effluent (35-54%). Therefore, actual effects of plant species on B removal was ranged from 45% to 25% between 5 and 40 ppm B treatments. Mass B removal within plant body (phytextraction) comprised the 13-10% of total loaded B in CW while the remaining part of the loaded B (31-15%) was stabilized into the sediment with the effects of poplar and willow roots. These results presented clear understanding of effective B purification mechanisms in CWs. Boron phytextraction capacity of a plant species was less effective than its phytstabilization efficiency which increase filtering capacity of the sediment and stabilization of more B around the rhizosphere. In terms of their B removal ability, P.nigra and S.anatolica had the highest B removal capacities with phytextraction (20-11%) while S.alba, P.alba and S.babylonica had more phytstabilizaiton performance (40-15%) in CW. Disposal of B loaded plant material create another environmental costs for CW applications. Therefore, B loaded
Extent and Effect of Horizontal Supply Chain Collaboration among Construction SME
Liv Torjussen
Full Text Available The majority of companies involved in value delivery in the Swedish housing industry are Small- and Medium-sized Enterprises (SME. An SME is often managed in an informal way with focus on sales and production. Many SME are also financially vulnerable as they are strongly dependent on a few key customers and key products. As variation will always exist, SME should learn to deal with variation instead of try eliminating it. This paper hypothesises that structural flexibility in SME supply chains through horizontal collaboration leads to a regional environment of economical growth from which all active SME will benefit. The hypothesis is examined through two case studies; a Swedish supplier network that has worked together six years and a four year old Norwegian supplier network. A benefit of collaboration is knowledge sharing that lessens the economical strain of keeping up with the "latest�. Other examples of collaboration are shared production resources in case of low capacity. Collaboration within supplier tier networks is considered to mark the emergence of a "collective strength� that improves individual suppliers bargaining position towards their customers. This evolution is considered an indication of the emergence of a "Lean Enterprise� within the house building sector.
Fate of heavy metals in vertical subsurface flow constructed wetlands treating secondary treated petroleum refinery wastewater in Kaduna, Nigeria.
Mustapha, Hassana Ibrahim; van Bruggen, J J A; Lens, P N L
This study examined the performance of pilot-scale vertical subsurface flow constructed wetlands (VSF-CWs) planted with three indigenous plants, i.e. Typha latifolia, Cyperus alternifolius, and Cynodon dactylon, in removing heavy metals from secondary treated refinery wastewater under tropical conditions. The T. latifolia-planted VSF-CW had the best heavy metal removal performance, followed by the Cyperus alternifolius-planted VSF-CW and then the Cynodon dactylon-planted VSF-CW. The data indicated that Cu, Cr, Zn, Pb, Cd, and Fe were accumulated in the plants at all the three VSF-CWs. However, the accumulation of the heavy metals in the plants accounted for only a rather small fraction (0.09-16%) of the overall heavy metal removal by the wetlands. The plant roots accumulated the highest amount of heavy metals, followed by the leaves, and then the stem. Cr and Fe were mainly retained in the roots of T. latifolia, Cyperus alternifolius, and Cynodon dactylon (TF < 1), meaning that Cr and Fe were only partially transported to the leaves of these plants. This study showed that VSF-CWs planted with T. latifolia, Cyperus Alternifolius, and Cynodon dactylon can be used for the large-scale removal of heavy metals from secondary refinery wastewater.
Nitrogen dynamics model for a pilot field-scale novel dewatered alum sludge cake-based constructed wetland system.
Kumar, J L G; Zhao, Y Q; Hu, Y S; Babatunde, A O; Zhao, X H
A model simulating the effluent nitrogen (N) concentration of treated animal farm wastewater in a pilot on-site constructed wetland (CW) system, using dewatered alum sludge cake (DASC) as wetland substrate, is presented. The N-model was developed based on the Structural Thinking Experiential Learning Laboratory with Animation software and is considering organic nitrogen, ammonia nitrogen (NH3) and nitrate nitrogen (NO3-N) as the major forms of nitrogen involved in the transformation chains. Ammonification (AMM), ammonia volatilization, nitrification (NIT), denitrification, plant uptake, plant decaying and uptake of inorganic nitrogen by algae and bacteria were considered in this model. pH, dissolved oxygen, temperature, precipitation, solar radiation and nitrogen concentrations were considered as forcing functions in the model. The model was calibrated by observed data with a reasonable agreement prior to its applications. The simulated effluent detritus nitrogen, NH4-N, NO3-N and TN had a considerably good agreement with the observed results. The mass balance analysis shows that NIT accounts for 65.60%, adsorption (ad) (11.90%), AMM (8.90%) followed by NH4-N (Plants) (5.90%) and NO3-N (Plants) (4.40%). The TN removal was found 52% of the total influent TN in the CW. This study suggested an improved overall performance of a DASC-based CW and efficient N removal from wastewater.
Leachate treatment system using constructed wetlands, Town of Fenton sanitary landfill, Broome County, New York. Final report
Municipal sanitary landfills generate leachate that New York State regulations require to be collected and treated to avoid contaminating surface water and groundwater. One option for treating leachate is to haul it to municipal wastewater treatment facility. This option may be expensive, may require excessive energy for transportation, and may require pretreatment to protect the receiving facility`s processes. An alternative is on-site treatment and discharge. Personnel from the Town of Fenton, New York; Hawk Engineering, P.C.; Cornell University; and Ithaca College designed, built, and operated a pilot constructed wetland for treating leachate at the Town of Fenton`s municipal landfill. The system, consisting of two overland flow beds and two subsurface flow beds has been effective for 18 months in reducing levels of ammonia (averaging 85% removal by volatilization and denitrification) and total iron (averaging 95% removal by precipitation and sedimentation), two key constituents of the Fenton landfill`s leachate. The system effects these reductions with zero chemical and energy inputs and minimal maintenance. A third key constituent of the leachate, manganese, apparently passes through the beds with minimal removal. Details and wetland considerations are described.
Removal of organics in constructed wetlands with horizontal sub-surface flow: A review of the field experience
Vymazal, Jan; Kröpfelová, L.
Ro�. 407, �. 13 (2009), s. 3911-3922 ISSN 0048-9697 Institutional research plan: CEZ:AV0Z60870520 Keywords : waste-water-treatment * aquatic plants * loading rate Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.905, year: 2009
Cost-Effectiveness Analysis of Surface Flow Constructed Wetlands (SFCW) for Nutrient Reduction in Drainage Discharge from Agricultural Fields in Denmark.
Gachango, F G; Pedersen, S M; Kjaergaard, C
Constructed wetlands have been proposed as cost-effective and more targeted technologies in the reduction of nitrogen and phosphorous water pollution in drainage losses from agricultural fields in Denmark. Using two pig farms and one dairy farm situated in a pumped lowland catchment as case studies, this paper explores the feasibility of implementing surface flow constructed wetlands (SFCW) based on their cost effectiveness. Sensitivity analysis is conducted by varying the cost elements of the wetlands in order to establish the most cost-effective scenario and a comparison with the existing nutrients reduction measures carried out. The analyses show that the cost effectiveness of the SFCW is higher in the drainage catchments with higher nutrient loads. The range of the cost effectiveness ratio on nitrogen reduction differs distinctively with that of catch crop measure. The study concludes that SFCW could be a better optimal nutrients reduction measure in drainage catchments characterized with higher nutrient loads.
Cost-effectiveness analysis of surface flow constructed wetlands (SFCW) for nutrient reduction in drainage discharge from agricultural fields in Denmark
Gachango, Florence Gathoni; Pedersen, Søren Marcus; Kjærgaard, Charlotte
Constructed wetlands have been proposed as cost-effective and more targeted technologies in the reduction of nitrogen and phosphorous water pollution in drainage losses from agricultural fields in Denmark. Using two pig farms and one dairy farm situated in a pumped lowland catchment as case studies......, this paper explores the feasibility of implementing surface flow constructed wetlands (SFCW) based on their cost effectiveness. Sensitivity analysis is conducted by varying the cost elements of the wetlands in order to establish the most cost-effective scenario and a comparison with the existing nutrients...... reduction measures carried out. The analyses show that the cost effectiveness of the SFCW is higher in the drainage catchments with higher nutrient loads. The range of the cost effectiveness ratio on nitrogen reduction differs distinctively with that of catch crop measure. The study concludes that SFCW...
High Pb concentration stress on Typha latifolia growth and Pb removal in microcosm wetlands.
Han, Jianqiu; Chen, Fengzhen; Zhou, Yumei; Wang, Chaohua
When constructed wetlands are used to treat high-Pb wastewater, Pb may become a stress to wetland plants, which subsequently reduces treatment performance and the other ecosystem services. To facilitate the design and operation of constructed wetlands for treatment of Pb-rich wastewater, we investigated the irreversible inhibitory level of Pb for Typha latifolia through experiments in microcosm wetlands. Seven horizontal subsurface flow constructed wetlands were built with rectangular plastic tanks and packed with marble chips and sand. All wetlands were transplanted with nine stems of Typha latifolia each. The wetlands were batch operated in a greenhouse with artificial wastewater (10 L each) for 12 days. Influent to the seven wetlands had different concentrations of Pb: 0 mg/L, 10 mg/L, 25 mg/L, 50 mg/L, 100 mg/L, 200 mg/L, and 500 mg/L, respectively. The results suggested that leaf chlorophyll relative content, relative growth rate, photosynthetic characteristics, activities of superoxide dismutase, peroxidase, and content of malondialdehyde were not affected when initial Pb concentration was at 100 mg/L and below. But when initial Pb concentration was above 100 mg/L, all of them were seriously affected. We conclude that high Pb concentrations wastewater could inhibit the growth of Typha latifolia and decrease the removal rate of wetlands.
Effectiveness of a model constructed wetland system containing Cyperus papyrus in degrading diesel oil
Harbowo, Danni Gathot; Choesin, Devi Nandita
Synergism between wetland systems and the provision of degrading bacterial inoculum is now being developed for the recovery of areas polluted waters of pollutants. In connection with the frequent cases of diesel oil pollution in the waters of Indonesia, we need a way of water treatment as an efficient. In this study conducted a series of tests to develop an construcred wetland design that can effectively degrade diesel oil. Tested five systems: blanko (A), substrated, without bacterial inoculums, and vegetation (B); with the addition of inoculum (C); subsrated and vegetated (D); substrated and vegetated with the addition of inoculum (E). Vegetation used in this study is Cyperus papyrus because it has the ability to absorb pollutants. Inoculum used was Pseudomonas aeruginosa and Enterobacter aerogenes which is a bacteria degrading organic compounds commonly found in water. To measure the effectiveness of the system, use several indicators to see the degradation of pollutants, namely changes in viscosity, surface tension of pollutants, and the emergence of compound degradation. Based on the results of the study can be determined that the substrated and vegetated system with Cyperus papyrus inoculum (E) was considered the most capable of degrading diesel oil due to the large changes in all parameters. In the system E, 40.6% increase viscosity, surface tension decreased 32.7%, the appearance of degradation compounds with relatively 3614.7 points, and increased to 227.8% TDS. In addition the environmental conditions in the system E also supports the growth of vegetation and degrading microbes.
Agronomic performance of tifton 85 (cynodon spp grass cultivated in constructed wetlands used in milk processing wastewater treatment
Odilon Gomes Pereira
Full Text Available The present work was carried out in order to study the performance of the tifton 85 (Cynodon spp grass cultivated in wetlands (SACs and submitted to different organic load application rates (TCOs of milk processing wastewater (ARL, in the climatic conditions of Viçosa - MG. The experimental structure was constituted by five SACs with horizontal subsuperficial flow, using tanks of 0.40 x 0.75 x 3.00 m (depth, width and length filled with 0.33 m depth of fine stones. The ARL was applied in average flow of 60 L.day-1, hydraulic time residence of 4.8 days and TCOs of 66, 130, 190, 320 and 570 kg.ha-1.day-1 of DBO. The tifton 85 grass adapted well to SACs, presenting good rooting, high yield and capacity of nutrients (N, P and K and sodium removal of the ARL, whose values were, respectively, between 216 - 544, 24 - 61, 115 - 204 and 4.3 – 10.9 kg.ha-1.
Horizontal gust response of `Tatara Bridge` under construction; `Tatara ohashi` kasetsuji no taifu anteisei
Matsuda, K.; Iwasaki, T.; Tokushige, M.; Toriumi, R. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)
Wind tunnel tests of a long-span cable-stayed bridge under construction were conducted with two types of turbulent boundary layer simulations. The level of agreement between the wind tunnel measurements and a wind buffeting analysis varied with the type of turbulent boundary layer. An investigation of this behavior found that the aerodynamic admittance used in the buffeting analysis was different from the measured aerodynamic admittance. Past research showed that buffeting analysis based on strip theory, which assumes a spanwise correlation between the fluctuating wind velocity and the fluctuating aerodynamic loads, does not always hold. (author)
Effects of aeration and natural zeolite on ammonium removal during the treatment of sewage by mesocosm-scale constructed wetlands.
Araya, F; Vera, I; Sáez, K; Vidal, G
The objective was to evaluate the effects of intermittent artificial aeration cycles and natural zeolite as a support medium, in addition to the contribution of plants (Schoenoplectus californicus) on NH4(+)-N removal during sewage treatment by Constructed Wetlands (CW). Two lines of Mesocosm Constructed Wetland (MCW) were installed: (a) gravel line (i.e. G-Line) and (b) zeolite line (i.e. Z-Line). Aeration increased the NH4(+)-N removal efficiency by 20-45% in the G-Line. Natural zeolite increased the NH4(+)-N removal efficiency by up to 60% in the Z-Line. Plants contributed 15-30% of the NH4(+)-N removal efficiency and no difference between the G-Line and the Z-Line. Conversely, the NH4(+)-N removal rate was shown to only increase with the use of natural zeolite. However, the MCW with natural zeolite, the NH4(+)-N removal rate showed a direct relationship only with the NH4(+)-N influent concentration. Additionally, relationship between the oxygen, energy and area regarding the NH4(+)-N removal efficiency was established for 2.5-12.5 gO2/(kWh-m(2)) in the G-Line and 0.1-2.6 gO2/(kWh-m(2)) in the Z-Line. Finally, it was established that a combination of natural zeolite as a support medium and the aeration strategy in a single CW could regenerate the zeolite's adsorption sites and maintain a given NH4(+)-N removal efficiency over time.
Simultaneous improvement of waste gas purification and nitrogen removal using a novel aerated vertical flow constructed wetland.
Zhang, Xinwen; Hu, Zhen; Ngo, Huu Hao; Zhang, Jian; Guo, Wenshan; Liang, Shuang; Xie, Huijun
Insufficient oxygen supply is identified as one of the major factors limiting organic pollutant and nitrogen (N) removal in constructed wetlands (CWs). This study designed a novel aerated vertical flow constructed wetland (VFCW) using waste gas from biological wastewater treatment systems to improve pollutant removal in CWs, its potential in purifying waste gas was also identified. Compared with unaerated VFCW, the introduction of waste gas significantly improved NH 4 + -N and TN removal efficiencies by 128.48 ± 3.13% and 59.09 ± 2.26%, respectively. Furthermore, the waste gas ingredients, including H 2 S, NH 3 , greenhouse gas (N 2 O) and microbial aerosols, were remarkably reduced after passing through the VFCW. The removal efficiencies of H 2 S, NH 3 and N 2 O were 77.78 ± 3.46%, 52.17 ± 2.53%, and 87.40 ± 3.89%, respectively. In addition, the bacterial and fungal aerosols in waste gas were effectively removed with removal efficiencies of 42.72 ± 3.21% and 47.89 ± 2.82%, respectively. Microbial analysis results revealed that the high microbial community abundance in the VFCW, caused by the introduction of waste gas from the sequencing batch reactor (SBR), led to its optimized nitrogen transformation processes. These results suggested that the VFCW intermittently aerated with waste gas may have potential application for purifying wastewater treatment plant effluent and waste gas, simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.
The dynamics of low-chlorinated benzenes in a pilot-scale constructed wetland and a hydroponic plant root mat treating sulfate-rich groundwater.
Chen, Zhongbing; Kuschk, Peter; Paschke, Heidrun; Kästner, Matthias; Köser, Heinz
A rarely used hydroponic plant root mat filter (PRMF, of 6 m(2)) and a horizontal subsurface flow constructed wetland (HSSF CW, of 6 m(2)), operating in continuous flow and discontinuous outflow flushing modes, were investigated for treating sulfate-rich and organic carbon-lean groundwater contaminated with monochlorobenzene (MCB); 1,2-dichlorobenzene (1,2-DCB); 1,4-dichlorobenzene (1,4-DCB); and 2-chlorotoluene. Whereas the mean inflow loads ranged from 1 to 247 mg m(-2) days(-1), the range of mean inflow concentrations of the chlorobenzenes recorded over a period of 7 months was within 0.04 and 8 mg L(-1). A hydraulic surface loading rate of 30 L m(-2) days(-1) was obtained in both systems. The mean load removal efficiencies were found to vary between 87 and 93 % in the PRMF after a flow path of 4 m, while the removal efficiencies were found to range between 46 and 70 % and 71 to 73 % in the HSSF CW operating in a continuous flow mode and a discontinuous outflow flushing mode, respectively. Seasonal variations in the removal efficiencies were observed for all low-chlorinated hydrocarbons both in the PRMF and the HSSF CW, whereby the highest removal efficiencies were reached during the summer months. Sulfide formation occurred in the organic carbon-lean groundwater particularly in summer, which is probably due to the plant-derived organic carbon that fostered the microbial dissimilatory sulfate reduction. Higher redox potential in water was observed in the PRMF. In conclusion, the PRMF could be an option for the treatment of water contaminated with compounds which in particular need oxic conditions for their microbial degradation, such as in the case of low-chlorinated benzenes.
The flower and the butterfly constructed wetland system at Koh Phi Phi - system design and lessons learned during implementation and operation
In 2007, a constructed wetland system was implemented on the tourist island of Koh Phi Phi in Southern Thailand. This paper presents the process of planning, designing and implementing the system and discusses the performance and operational issues 3 years after implementation. The system is an i...
Evaluation of two hybrid poplar clones as constructed wetland plant species for treating saline water high in boron and selenium, or waters only high in boron
Wetland mesocosms were constructed to assess two salt- and B-tolerant hybrid poplar clones (Populus trichocarpa ×P. deltoides×P. nigra '345-1' and '347-14') for treating saline water high in boron (B) and selenium (Se). In addition, a hydroponic experiment was performed to test the B tolerance and B...
Evapotranspiration versus oxygen intrusion: which is the main force in alleviating bioclogging of vertical-flow constructed wetlands during a resting operation?
Hua, Guofen; Chen, Qiuwen; Kong, Jun; Li, Man
Clogging is the most significant challenge limiting the application of constructed wetlands. Application of a forced resting period is a practical way to relieve clogging, particularly bioclogging. To reveal the alleviation mechanisms behind such a resting operation, evapotranspiration and oxygen flux were studied during a resting period in a laboratory vertical-flow constructed wetland model through physical simulation and numerical model analysis. In addition, the optimum theoretical resting duration was determined based on the time required for oxygen to completely fill the pores, i.e., formation of a sufficiently thick and completely dry layer. The results indicated that (1) evapotranspiration was not the key factor, but was a driving force in the alleviation of bioclogging; (2) the rate of oxygen diffusion into the pores was sufficient to oxidize and disperse the flocculant biofilm, which was essential to alleviate bioclogging. This study provides important insights into understanding how clogging/bioclogging can be alleviated in vertical-flow constructed wetlands. Graphical abstract Evapotranspiration versus oxygen intrusion in alleviating bioclogging in vertical flow constructed wetlands.
Design and performance of the constructed wetland wastewater treatment system at Phillips High School, Bear Creek, Alabama
A constructed wetlands waste water treatment system has been constructed at Phillips High School, Bear Creek, Alabama, to polish the effluent from the school's extended aeration package treatment plant. The project is a demonstration of innovative technology under the Congressionally appropriated Bear Creek Floatway projects. Construction was completed in August 1988 at a cost of $36,266. Monitoring results for the period October 1988 through July 1989 reveal that the system has been very effective in polishing the effluent from the package treatment plant. The effectiveness is attributed primarily to maintenance of an overall oxidizing environment within the gravel substrate. Average monthly removals during the first year of operation exceeded 90 percent for BOD, TSS, organic nitrogen, total phosphorus, dissolved phosphorus, and fecal coliforms. Average removal percentages ranged in the 80s for ammonia and total nitrogen and in the 70s for nitrate + nitrite nitrogen and dissolved BOD. The prevalence of oxidizing conditions is probably the result of low carbonaceous demand, the low inlet hydraulic loading rate, and the combination of the shallow gravel depth and the excellent plant coverage and root depths during the first year of operation. 11 refs., 17 figs., 2 tabs.
Total and methyl mercury concentrations in sediment and water of a constructed wetland in the Athabasca Oil Sands Region.
Oswald, Claire J; Carey, Sean K
In the Athabasca Oil Sands Region in northeastern Alberta, Canada, oil sands operators are testing the feasibility of peatland construction on the post-mining landscape. In 2009, Syncrude Canada Ltd. began construction of the 52 ha Sandhill Fen pilot watershed, including a 15 ha, hydrologically managed fen peatland built on sand-capped soft oil sands tailings. An integral component of fen reclamation is post-construction monitoring of water quality, including salinity, fluvial carbon, and priority pollutant elements. In this study, the effects of fen reclamation and elevated sulfate levels on mercury (Hg) fate and transport in the constructed system were assessed. Total mercury (THg) and methylmercury (MeHg) concentrations in the fen sediment were lower than in two nearby natural fens, which may be due to the higher mineral content of the Sandhill Fen peat mix and/or a loss of Hg through evasion during the peat harvesting, stockpiling and placement processes. Porewater MeHg concentrations in the Sandhill Fen typically did not exceed 1.0 ng L(-1). The low MeHg concentrations may be a result of elevated porewater sulfate concentrations (mean 346 mg L(-1)) and an increase in sulphide concentrations with depth in the peat, which are known to suppress MeHg production. Total Hg and MeHg concentrations increased during a controlled mid-summer flooding event where the water table rose above the ground surface in most of the fen. The Hg dynamics during this event showed that hydrologic fluctuations in this system exacerbate the release of THg and MeHg downstream. In addition, the elevated SO4(2-) concentrations in the peat porewaters may become a problem with respect to downstream MeHg production once the fen is hydrologically connected to a larger wetland network that is currently being constructed. Copyright © 2016 Elsevier Ltd. All rights reserved.
Floodplain/wetland assessment of the effects of construction and operation ofa depleted uranium hexafluoride conversion facility at the Paducah, Kentucky,site.
The U.S. Department of Energy (DOE) Depleted Uranium Hexafluoride (DUF{sub 6}) Management Program evaluated alternatives for managing its inventory of DUF{sub 6} and issued the ''Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted Uranium Hexafluoride'' (DUF{sub 6} PEIS) in April 1999 (DOE 1999). The DUF{sub 6} inventory is stored in cylinders at three DOE sites: Paducah, Kentucky; Portsmouth, Ohio; and East Tennessee Technology Park (ETTP), near Oak Ridge, Tennessee. In the Record of Decision for the DUF{sub 6} PEIS, DOE stated its decision to promptly convert the DUF{sub 6} inventory to a more stable chemical form. Subsequently, the U.S. Congress passed, and the President signed, the ''2002 Supplemental Appropriations Act for Further Recovery from and Response to Terrorist Attacks on the United States'' (Public Law No. 107-206). This law stipulated in part that, within 30 days of enactment, DOE must award a contract for the design, construction, and operation of a DUF{sub 6} conversion plant at the Department's Paducah, Kentucky, and Portsmouth, Ohio, sites, and for the shipment of DUF{sub 6} cylinders stored at ETTP to the Portsmouth site for conversion. This floodplain/wetland assessment has been prepared by DOE, pursuant to Executive Order 11988 (''Floodplain Management''), Executive Order 11990 (Protection of Wetlands), and DOE regulations for implementing these Executive Orders as set forth in Title 10, Part 1022, of the ''Code of Federal Regulations'' (10 CFR Part 1022 [''Compliance with Floodplain and Wetland Environmental Review Requirements'']), to evaluate potential impacts to floodplains and wetlands from the construction and operation of a conversion facility at the DOE Paducah site. Reconstruction of the bridge crossing Bayou Creek would occur within the Bayou Creek 100-year
Assessing metal contamination from construction and demolition (C&D) waste used to infill wetlands: using Deroceras reticulatum (Mollusca: Gastropoda).
Staunton, John A; Mc Donnell, Rory J; Gormally, Michael J; Williams, Chris D; Henry, Tiernan; Morrison, Liam
Large quantities of construction and demolition waste (C&D) are produced globally every year, with little known about potential environmental impacts. In the present study, the slug, Deroceras reticulatum (Mollusca: Gastropoda) was used as the first biomonitor of metals (Ag, As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, Se, Ti, Tl, V and Zn) on wetlands post infilling with construction and demolition (C&D) waste. The bioaccumulation of As, Ba, Cd, Co, Sb, Se and Tl were found to be significantly elevated in slugs collected on C&D waste when compared to unimproved pastures (control sites), while Mo, Se and Sr had significantly higher concentrations in slugs collected on C&D waste when compared to known contaminated sites (mining locations), indicating the potential hazardous nature of C&D waste to biota. Identifying exact sources for these metals within the waste can be problematic, due to its heterogenic nature. Biomonitors are a useful tool for future monitoring and impact studies, facilitating policy makers and regulations in other countries regarding C&D waste infill. In addition, improving separation of C&D waste to allow increased reuse and recycling is likely to be effective in reducing the volume of waste being used as infill, subsequently decreasing potential metal contamination.
Total and methyl mercury concentrations in sediment and water of a constructed wetland in the Athabasca Oil Sands Region
Oswald, Claire J.; Carey, Sean K.
In the Athabasca Oil Sands Region in northeastern Alberta, Canada, oil sands operators are testing the feasibility of peatland construction on the post-mining landscape. In 2009, Syncrude Canada Ltd. began construction of the 52 ha Sandhill Fen pilot watershed, including a 15 ha, hydrologically managed fen peatland built on sand-capped soft oil sands tailings. An integral component of fen reclamation is post-construction monitoring of water quality, including salinity, fluvial carbon, and priority pollutant elements. In this study, the effects of fen reclamation and elevated sulfate levels on mercury (Hg) fate and transport in the constructed system were assessed. Total mercury (THg) and methylmercury (MeHg) concentrations in the fen sediment were lower than in two nearby natural fens, which may be due to the higher mineral content of the Sandhill Fen peat mix and/or a loss of Hg through evasion during the peat harvesting, stockpiling and placement processes. Porewater MeHg concentrations in the Sandhill Fen typically did not exceed 1.0 ng L −1 . The low MeHg concentrations may be a result of elevated porewater sulfate concentrations (mean 346 mg L −1 ) and an increase in sulphide concentrations with depth in the peat, which are known to suppress MeHg production. Total Hg and MeHg concentrations increased during a controlled mid-summer flooding event where the water table rose above the ground surface in most of the fen. The Hg dynamics during this event showed that hydrologic fluctuations in this system exacerbate the release of THg and MeHg downstream. In addition, the elevated SO 4 2− concentrations in the peat porewaters may become a problem with respect to downstream MeHg production once the fen is hydrologically connected to a larger wetland network that is currently being constructed. - Highlights: • A constructed fen peatland in the Athabasca Oil Sands Region was studied. • Total and methyl mercury concentrations in fen sediment and waters
Effects of Pipeline Construction on Wetland Ecosystems: Russia-China Oil Pipeline Project (Mohe-Daqing Section)
Xiaofei Yu; Guoping Wang; Yuanchun Zou; Qiang Wang; Hongmei Zhao; Xianguo Lu (Key Lab of Wetland Ecology and Environment, Northeast Inst. of Geography and Agroecology, Changchun (China)), e-mail: wangguoping@neigae.ac.cn
Although the multiple roles of wetland ecosystems and their value to humanity have been increasingly understood and documented in recent years, the efforts to conserve and restore wetlands are not in harmony with the press for high speed of economy growth. The degradation of wetlands is proceeding, especially in China. Russia- China Oil Pipe-line Project (Mohe-Daqing Section) has already begun in May 2009, and is ongoing. The pipeline runs through four riverine wetlands and two marshlands of Heilongjiang Province, Northeast China. Although the project has vital significance of mitigating the energy crisis as well as guaranteeing the energy security of China, it will bring a series of ecological and environmental problems, especially for wetland ecosystems
Constructed wetland mesocosms for the treatment of diluted sugarcane molasses stillage from ethanol production using Pontederia sagittata.
Olguín, Eugenia J; Sánchez-Galván, Gloria; González-Portela, Ricardo E; López-Vela, Melissa
Sugarcane molasses stillage contains a very high concentration of organic matter and toxic/recalcitrant compounds. Its improper disposal has become a global problem and there is very scanty information about its treatment using phytotechnologies. This work aimed at evaluating the performance of subsurface flow constructed wetlands (SSF CWs) mesocosms planted with Pontederia sagittata and operating at two hydraulic retention times (HRTs), compared to an unplanted SSF CWs, for the treatment of diluted stillage subjected to no pre-treatment apart from an adjustment to pH 6.0. CWs were fed with very high surface COD loading rates (i.e. 47.26 and 94.83gCOD/m(2)d). The planted CWs were able to remove COD in the range of 80.24-80.62%, BOD(5) in the range of 82.20-87.31%, TKN in the range of 73.42-76.07%, nitrates from 56-58.74% and sulfates from 68.58-69.45%, depending on the HRT. Phosphate and potassium were not removed. It was concluded that this type of CWs is a feasible option for the treatment of diluted stillage.
Can constructed wetlands treat wastewater for reuse in agriculture? Review of guidelines and examples in South Europe.
Lavrnić, Stevo; Mancini, Maurizio L
South Europe is one of the areas negatively affected by climate change. Issues with water shortage are already visible, and are likely to increase. Since agriculture is the biggest freshwater consumer, it is important to find new water sources that could mitigate the climate change impact. In order to overcome problems and protect the environment, a better approach towards wastewater management is needed. That includes an increase in the volume of wastewater that is treated and a paradigm shift towards a more sustainable system where wastewater is actually considered as a resource. This study evaluates the potential of constructed wetlands (CWs) to treat domestic wastewater and produce effluent that will be suitable for reuse in agriculture. In South Europe, four countries (Greece, Italy, Portugal and Spain) have national standards that regulate wastewater reuse in agriculture. Wastewater treatment plants (WWTPs) that are based on CWs in these four countries were analysed and their effluents compared with the quality needed for reuse. In general, it was found that CWs have trouble reaching the strictest standards, especially regarding microbiological parameters. However, their effluents are found to be suitable for reuse in areas that do not require water of the highest quality.
Effects of Selected Root Exudate Components on Nitrogen Removal and Development of Denitrifying Bacteria in Constructed Wetlands
Hailu Wu
Full Text Available Root exudates, particularly low molecular weight carbon (LMWC substrates, are major drivers of bacterial diversity and activity in the rhizosphere environment. However, it is not well understood how specific LMWC compounds—such as organic acids, soluble sugars, and amino acids—influence the community structures of denitrifying bacteria or if there are specific functions of LMWC substrates that preferentially respond to nitrogen (N removal in constructed wetlands (CWs. To address these knowledge gaps, we added mixtures of artificial exudates to CW microcosms containing N pollutant. N removal efficiency was observed over a 48-h experimental period, and at the end of the experiment, DNA was extracted from microbial samples for assessment of the bacterial community. The removal efficiencies of TN for the exudates treatments were higher than for control groups by 47.1–58.67%. Organic acid and soluble sugar treatments increased N removal, while amino acids were negative to N removal. The microbial community was changed when artificial exudates were added, but there were no significant relationships between LMWC compounds and bacterial community composition. These results indicate that although the responses of community structures of denitrifying bacteria to LMWC additions are still uncertain, there is evidence for N removal in response to exudate additions across LMWC types.
Influence of loading rate and modes on infiltration of treated wastewater in soil-based constructed wetland.
Bisone, Sara; Gautier, Mathieu; Masson, Matthieu; Forquet, Nicolas
Over the last 10 years soil-based constructed wetlands for discharge of treated wastewater (TWW) are commonly presented as a valuable option to provide tertiary treatment. The uncomplete knowledge in soil modifications and a lack of clear design practices laid the foundation of this work. The aim of this study was to determine optimal hydraulic loads and to observe the main critical parameters affecting treating performances and hydraulic loads acceptance. For this purpose, a soil rich in clay and backfill was chosen to perform column infiltration tests with TWW. Two loading rates and two loading modes were compared to study the influence of an intermittent feeding. Inlet and outlet waters were periodically analysed and columns were instrumented with balances, tensiometers, O 2 and temperature probes. Soil physico-chemical characteristics were also taken into account to better understand the modification of the soil. One of the main expectations of tertiary treatment is to improve phosphate removal. A particular attention was thus given to phosphorus retention. The interest of an intermittent feeding in presence of a soil with high clay content was showed. This study highlighted that an intermittent feeding could make possible the use of a clay-rich soil for water infiltration.
Effects of carbon sources and COD/N ratio on N2O emissions in subsurface flow constructed wetlands.
Lyu, Wanlin; Huang, Lei; Xiao, Guangquan; Chen, Yucheng
A set of constructed wetlands under two different carbon sources, namely, glucose (CW) and sodium acetate (YW), was established at a laboratory scale with influent COD/N ratios of 20:1, 10:1, 7:1, 4:1, and 0 to analyze the influence of carbon supply on nitrous oxide emissions. Results showed that the glucose systems generated higher N 2 O emissions than those of the sodium acetate systems. The higher amount of N 2 O-releasing fluxes in the CWs than in the YWs was consistent with the higher NO 2 - -N accumulation in the former than in the latter. Moreover, electron competition was tighter in the CWs and contributed to the incomplete denitrification with poor N 2 O production performance. Illumina MiSeq sequencing demonstrated that some denitrifying bacteria, such as Denitratisoma, Bacillus, and Zoogloea, were higher in the YWs than in the CWs. This result indicated that the carbon source is important in controlling N 2 O emissions in microbial communities. Copyright © 2017. Published by Elsevier Ltd.
Decomposition characteristics of three different kinds of aquatic macrophytes and their potential application as carbon resource in constructed wetland.
Wu, Suqing; He, Shengbing; Zhou, Weili; Gu, Jianya; Huang, Jungchen; Gao, Lei; Zhang, Xu
Decomposition of aquatic macrophytes usually generates significant influence on aquatic environment. Study on the aquatic macrophytes decomposition may help reusing the aquatic macrophytes litters, as well as controlling the water pollution caused by the decomposition process. This study verified that the decomposition processes of three different kinds of aquatic macrophytes (water hyacinth, hydrilla and cattail) could exert significant influences on water quality of the receiving water, including the change extent of pH, dissolved oxygen (DO), the contents of carbon, nitrogen and phosphorus, etc. The influence of decomposition on water quality and the concentrations of the released chemical materials both followed the order of water hyacinth > hydrilla > cattail. Greater influence was obtained with higher dosage of plant litter addition. The influence also varied with sediment addition. Moreover, nitrogen released from the decomposition of water hyacinth and hydrilla were mainly NH 3 -N and organic nitrogen while those from cattail litter included organic nitrogen and NO 3 - -N. After the decomposition, the average carbon to nitrogen ratio (C/N) in the receiving water was about 2.6 (water hyacinth), 5.3 (hydrilla) and 20.3 (cattail). Therefore, cattail litter might be a potential plant carbon source for denitrification in ecological system of a constructed wetland. Copyright © 2017 Elsevier Ltd. All rights reserved.
Nitrogen removal and recovery from lagoon-pretreated swine wastewater by constructed wetlands under sustainable plant harvesting management.
Luo, Pei; Liu, Feng; Zhang, Shunan; Li, Hongfang; Yao, Ran; Jiang, Qianwen; Xiao, Runlin; Wu, Jinshui
A series of three-stage pilot-scale surface flow constructed wetlands (CWs) planted with Myriophyllum aquaticum were fed with three strengths of lagoon-pretreated swine wastewater to study nitrogen (N) removal and recovery under sustainable plant harvesting management. The CWs had mean removal efficiency of 87.7-97.9% for NH 4 + -N and 85.4-96.1% for total N (TN). The recovered TN mass via multiple harvests of M. aquaticum was greatest (120-222 g N m -2  yr -1 ) when TN concentrations were 21.8-282 mg L -1 . The harvested TN mass accounted for 0.85-100% of the total removal in the different CW units. Based on mass balance estimation, plant uptake, sediment storage, and microbial removal accounted for 13.0-55.0%, 4.9-8.0%, and 33.0-67.5% of TN loading mass, respectively. The results of this study confirm that M. aquaticum is appropriate for the removal and recovery of nutrients in CW systems designed for treating swine wastewater in conjunction with sustainable plant harvesting strategies. Copyright © 2018 Elsevier Ltd. All rights reserved.
Multiple antibiotic resistance patterns of rhizospheric bacteria isolated from Phragmites australis growing in constructed wetland for distillery effluent treatment.
Chaturvedi, Sonal; Chandra, Ram; Rai, Vibhuti
Susceptibility patterns of 12 different antibiotics were investigated against rhizospheric bacteria isolated from Phragmites australis from three different zones i.e. upper (0-5 cm), middle (5-10 cm), lower (10-15 cm) in constructed wetland system with and without distillery effluent. The major pollutants of distillery effluent were phenols, sulphide, heavy metals, and higher levels of biological oxygen demand (BOD), chemical oxygen demand (COD) etc. The antibiotic resistance properties of bacteria were correlated with the heavy metal tolerance (one of distillery pollutant). Twenty-two species from contaminated and seventeen species from non-contaminated site were tested by agar disc-diffusion method. The results revealed that more than 63% of total isolates were resistance towards one or more antibiotics tested from all the three different zones of contaminated sites. The multiple-drug resistance property was shown by total 8 isolates from effluent contaminated region out of which 3 isolates were from upper zone, 3 isolates from middle zone and 2 isolates were from lower zone. Results indicated that isolates from contaminated rhizosphere were found more resistant to antibiotics than isolates from non-contaminated rhizosphere. Further this study produces evidence suggesting that tolerance to antibiotics was acquired by isolates for the adaptation and detoxification of all the pollutants present in the effluent at contaminated site. This consequently facilitated the phytoremediation of effluent, which emerges the tolerance and increases resistance to antibiotics.
A novel aerated surface flow constructed wetland using exhaust gas from biological wastewater treatment: Performance and mechanisms.
Zhang, Xinwen; Hu, Zhen; Zhang, Jian; Fan, Jinlin; Ngo, Huu Hao; Guo, Wenshan; Zeng, Chujun; Wu, Yiwen; Wang, Siyuan
In this study, a novel aerated surface flow constructed wetland (SFCW) using exhaust gas from biological wastewater treatment was investigated. Compared with un-aerated SFCW, the introduction of exhaust gas into SFCW significantly improved NH 4 + -N, TN and COD removal efficiencies by 68.30 ± 2.06%, 24.92 ± 1.13% and 73.92 ± 2.36%, respectively. The pollutants removal mechanism was related to the microbial abundance and the highest microbial abundance was observed in the SFCW with exhaust gas because of the introduction of exhaust gas from sequencing batch reactor (SBR), and thereby optimizing nitrogen transformation processes. Moreover, SFCW would significantly mitigate the risk of exhaust gas pollution. SFCW removed 20.00 ± 1.23%, 34.78 ± 1.39%, and 59.50 ± 2.33% of H 2 S, NH 3 and N 2 O in the exhaust gas, respectively. And 31.32 ± 2.23% and 32.02 ± 2.86% of bacterial and fungal aerosols in exhaust gas were also removed through passing SFCW, respectively. Copyright © 2017. Published by Elsevier Ltd.
Hamadeh, Ahmed F.
Constructed wetlands (CWs) and managed aquifer recharge (MAR) represent commonly used natural treatment systems for reclamation and reuse of wastewater. However, each of these technologies have some limitations with respect to removal of different contaminants. Combining these two technologies into a hybrid CW-MAR system will lead to synergy in terms of both water quality and costs. This promising technology will help in the reduction of bacteria and viruses, trace and heavy metals, organic micropollutants, and nutrients. Use of subsurface flow CWs as pre-treatment for MAR has multiple benefits: (i) it creates a barrier for different microbial and chemical pollutants, (ii) it reduces the residence time for water recovery, and (iii) it avoids clogging during MAR as CWs can remove suspended solids and enhance the reclaimed water quality. This paper analyzes the removal of different contaminants by CW and MAR systems based on a literature review. It is expected that a combination of these natural treatment systems (CWs and MAR) could become an attractive, efficient and cost-effective technology for water reclamation and reuse. © IWA Publishing 2014.
Using one filter stage of unsaturated/saturated vertical flow filters for nitrogen removal and footprint reduction of constructed wetlands.
Morvannou, Ania; Troesch, Stéphane; Esser, Dirk; Forquet, Nicolas; Petitjean, Alain; Molle, Pascal
French vertical flow constructed wetlands (VFCW) treating raw wastewater have been developed successfully over the last 30 years. Nevertheless, the two-stage VFCWs require a total filtration area of 2-2.5 m 2 /P.E. Therefore, implementing a one-stage system in which treatment performances reach standard requirements is of interest. Biho-Filter ® is one of the solutions developed in France by Epur Nature. Biho-Filter ® is a vertical flow system with an unsaturated layer at the top and a saturated layer at the bottom. The aim of this study was to assess this new configuration and to optimize its design and operating conditions. The hydraulic functioning and pollutant removal efficiency of three different Biho-Filter ® plants commissioned between 2011 and 2012 were studied. Outlet concentrations of the most efficient Biho-Filter ® configuration are 70 mg/L, 15 mg/L, 15 mg/L and 25 mg/L for chemical oxygen demand (COD), 5-day biological oxygen demand (BOD 5 ), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN), respectively. Up to 60% of total nitrogen is removed. Nitrification efficiency is mainly influenced by the height of the unsaturated zone and the recirculation rate. The optimum recirculation rate was found to be 100%. Denitrification in the saturated zone works at best with an influent COD/NO 3 -N ratio at the inflet of this zone larger than 2 and a hydraulic retention time longer than 0.75 days.
Nutrient uptake from liquid digestate using ornamental aquatic macrophytes (Canna indica, Iris pseudacorus, Typha latifolia) in a constructed wetland system
Ediviani, W.; Priadi, C. R.; Moersidik, S. S.
Indonesia has implemented energy recovery from organic (food) waste by anaerobic digestion method, but the digestate was commonly treated only by composting, and still as a separated treatment (not integrated into a resource recovery system). Whilst not getting any pretreatment, the digestate was disposed to the environment and then act as a pollutant. Yet it contains nutrients which could be recovered as a nutrient source for plants. The study was about how ornamental aquatic macrophytes could uptake nitrogen from liquid digestate in a constructed wetland method. Canna indica, Iris pseudacorus, and Typha latifolia were the experimented ornamental aquatic macrophytes used to uptake the nutrient (nitrogen—N) from liquid digestate. The study showed that the highest N uptake was done by C. indica (25.1%) which has the highest biomass increment as well (80.5%). Effluent quality improvement also shown by N removal by C. indica (68.5—76.4% TN), I. pseudacorus (61.8—71.3% TN), and T. latifolia (61.6—74.5%). This research proved that C. indica has the performance for the N uptake, best N removal efficiency, with a great growth rate as well. This system using C. indica could also improve the water quality of the effluent and add the aesthetic of environment.
Internal oxygen dynamics in rhizomes of Phragmites australis and presence of methanotrophs in root biofilms in a constructed wetland for wastewater treatment
Faußer, A.; Dušek, Jiří; Čížková, Hana; Hoppert, M.; Walther, P.; Kazda, M.
Ro�. 51, 13-15 (2013), s. 3026-3031 ISSN 1944-3994. [3rd International Conference on Environmental Management, Engineering, Planning and Economics (CEMEPE) and SECOTOX Conference. Skiathos Island, 19.06.2011-24.06.2011] Institutional support: RVO:67179843 Keywords : Aerenchyma * Macrophyte * Constructed wetland * Internal oxygen partial pressure * Methane-oxidising bacteria Subject RIV: EH - Ecology, Behaviour Impact factor: 0.988, year: 2013
Effects of the inclusion of a mixed Psychrotrophic bacteria strain for sewage treatment in constructed wetland in winter seasons.
Tang, Meizhen; Li, Zhengtao; Yang, Yuewei; Chen, Junfeng; Jiang, Jie
Constructed wetlands (CWs) have been used globally in wastewater treatment for years. CWs represent an efficient ecological system which is both energy-saving and low in investment for construction and operational cost. In addition, CWs also have the advantage of being easy to operate and maintain. However, the operation of CWs at northern latitudes (both mid and high) is sometimes quite demanding, due to the inhibitory effect of low temperatures that often occur in winter. To evaluate the wastewater treatment performance of a culture of mixed Psychrotrophic bacteria strains in an integrated vertical-flow CW, the removal rates of ammonia nitrogen (NH 3 -N), chemical oxygen demand (COD), nitrite nitrogen [Formula: see text], nitrate nitrogen [Formula: see text] and total phosphorus (TP) were quantified at different bacterial dosages to determine the best bacterial dosage and establish kinetic degradation models of the mixed strains. The bacterial culture was made up of Psychrobacter TM-1, Sphingobacterium TM-2 and Pseudomonas TM-3, mixed together at a volume/volume ratio of 1 : 1 : 1 (at bacterial suspension concentrations of 4.4 × 10 9  ml -1 ). Results showed that the organic pollutants (nitrogen and phosphorus) in the sewage could be efficiently removed by the culture of mixed Psychrotrophic bacteria. The optimal dosage of this mixed bacteria strain was 2.5%, and the treatment efficiency of COD, NH 3 -N, [Formula: see text], [Formula: see text], total nitrogen and TP were stable at 91.8%, 91.1%, 88.0%, 93.8%, 94.8% and 95.2%, respectively, which were 1.5, 2.0, 2.1, 1.5, 2.2 and 1.3 times those of the control group. In addition, a pseudo-first-order degradation model was a good fit for the degradation pattern observed for each of these pollutants.
Experiences from the full-scale implementation of a new two-stage vertical flow constructed wetland design.
Langergraber, Guenter; Pressl, Alexander; Haberl, Raimund
This paper describes the results of the first full-scale implementation of a two-stage vertical flow constructed wetland (CW) system developed to increase nitrogen removal. The full-scale system was constructed for the Bärenkogelhaus, which is located in Styria at the top of a mountain, 1,168 m above sea level. The Bärenkogelhaus has a restaurant with 70 seats, 16 rooms for overnight guests and is a popular site for day visits, especially during weekends and public holidays. The CW treatment system was designed for a hydraulic load of 2,500 L.d(-1) with a specific surface area requirement of 2.7 m(2) per person equivalent (PE). It was built in fall 2009 and started operation in April 2010 when the restaurant was re-opened. Samples were taken between July 2010 and June 2013 and were analysed in the laboratory of the Institute of Sanitary Engineering at BOKU University using standard methods. During 2010 the restaurant at Bärenkogelhaus was open 5 days a week whereas from 2011 the Bärenkogelhaus was open only on demand for events. This resulted in decreased organic loads of the system in the later period. In general, the measured effluent concentrations were low and the removal efficiencies high. During the whole period the ammonia nitrogen effluent concentration was below 1 mg/L even at effluent water temperatures below 3 °C. Investigations during high-load periods, i.e. events like weddings and festivals at weekends, with more than 100 visitors, showed a very robust treatment performance of the two-stage CW system. Effluent concentrations of chemical oxygen demand and NH4-N were not affected by these events with high hydraulic loads.
Desing and construction of a horizontally placed superconducting magnet and its cryostat for an electron beam ion source
Kobayashi, N.; Ohtani, S.; Kaneko, Y.; Iwai, T.; Okuno, K.
An electron beam ion source nicknamed NICE-I (Naked Ion Collision Experiments) has been constructed at IPP for studies of atomic processes in fusion plasmas. A super conducting magnet is adopted to generate a strong, stable and homogenious magnetic field to compress a high density electron beam. The solenoid is 1 m long, the inner diameter is 100 mm and the maximum magnetic field is 2T. It is placed horizontally and coaxially with a liquid nitrogen (L-N 2 ) reservoir and a vaccum vessel. In order to fix their axes inmovable even when the reservoirs are cooled by L-N 2 and He, a structure having spokes strained uniformly like a wheel is used between the vaccum vessel and the L-N 2 reservoir and also between the L-N 2 reservoir and the solenoid bore. The electrodes, such as the electron gun, the drift tubes and so on, are mounted on the radiation shields fixed on the L-N 2 reservoir, and they are centered to the solenoid bore within the precision of 0.1 mm. The evapolation rate of L-He is about 1.4 l/h, which is not so much larger than the estimated value. This provides a continuous operation for 16 hours with a charge of 50 l L-He including the precooling of the reservoir. The ultimate pressure 4 x 10 -10 Torr is achived in the vacuum vessel, and the residual gas pressure in the ionization region is expected to be much lower than 1 x 10 -10 Torr. The consideration for mechanical strength and the heat conduction of the materials related to the design are described as well as the details of the structure. (author)
The influence of managed versus natural hydrologic regimes on the hydrochemical patterns in a constructed wetland in the Athabasca oil sands region, Canada.
Biagi, K.; Oswald, C.; Nicholls, E.; Carey, S.
Bitumen extraction via surface mining in the Athabasca Oil Sands Region (AOSR) results in permanent alteration of the landscape once rich in boreal forest and wetlands. As part of their legal requirements, oil companies must reclaim disturbed landscapes into functioning ecosystems, and to date only two pilot wetland-peatland systems have been constructed. Peatland reclamation is challenging as they must be completely reconstructed with few guidelines or previous work in this region. Furthermore, the variable sub-humid climate and salinity of waste-materials are obstacles to the success of peatland creation. In 2012, Syncrude Canada Ltd. constructed a 52 ha upland-wetland system, the Sandhill Fen Watershed (SFW), which was designed with a pump and underdrain system to provide freshwater and enhance drainage to limit salinization from underlying waste materials that have elevated electrical conductivity (EC) and Na+. The objective of this research is to understand the hydrochemical response of a constructed wetland to variations in hydrological management with respect to sources, flow pathways and major chemical transformations of water in the three years following commissioning. EC, major ions and stable isotopes were collected using a combination of high frequency and discrete water sampling from 2013-2015. Results indicate that high activity of both inflow and outflow pumps in 2013 kept the EC relatively low, with most wetland sites 1000 µS/cm in 2014 and >2000 µS/cm in 2015. Most wetland sites remained Ca+2 dominant where Ca+2 and Na+ averaged 200 and 130 mg/L, respectively. However, the most notable change in 2014 and 2015 was the emergence of several Na+ "hotspots" in the margins where Na+ concentrations averaged 450 mg/L while Ca+2 averaged 250 mg/L. Stable isotope data confirm that the "hotspots" match the underlying waste water and provide evidence of its upward transport and seepage under a natural hydrologic regime. Minimizing salinization is critical
Remediation of sediment and water contaminated by copper in small-scaled constructed wetlands: effect of bioaugmentation and phytoextraction.
Huguenot, D; Bois, P; Cornu, J Y; Jezequel, K; Lollier, M; Lebeau, T
The use of plants and microorganisms to mitigate sediment contaminated by copper was studied in microcosms that mimic the functioning of a stormwater basin (SWB) connected to vineyard watershed. The impact of phytoremediation and bioaugmentation with siderophore-producing bacteria on the fate of Cu was studied in two contrasted (batch vs. semi-continuous) hydraulic regimes. The fate of copper was characterised following its discharge at the outlet of the microcosms, its pore water concentration in the sediment, the assessment of its bioaccessible fraction in the rhizosphere and the measurement of its content in plant tissues. Physico-chemical (pH, redox potential) and biological parameters (total heterotrophic bacteria) were also monitored. As expected, the results showed a clear impact of the hydraulic regime on the redox potential and thus on the pore water concentration of Cu. Copper in pore water was also dependent on the frequency of Cu-polluted water discharges. Repeated bioaugmentation increased the total heterotrophic microflora as well as the Cu bioaccessibility in the rhizosphere and increased the amount of Cu extracted by Phragmites australis by a factor of ~2. Sugar beet pulp, used as a filter to avoid copper flushing, retained 20% of outcoming Cu and led to an overall retention of Cu higher than 94% when arranged at the outlet of microcosms. Bioaugmentation clearly improved the phytoextraction rate of Cu in a small-scaled SWB designed to mimic the functioning of a full-size SWB connected to vineyard watershed. Highlights: Cu phytoextraction in constructed wetlands much depends on the hydraulic regime and on the frequency of Cu-polluted water discharges. Cu phytoextraction increases with time and plant density. Cu bioaccessibility can be increased by bioaugmentation with siderophore-producing bacteria.
Assessing the Ecological Relevance of Organic Discharge Limits for Constructed Wetlands by Means of a Model-Based Analysis
Natalia Donoso
Full Text Available Polder watercourses within agricultural areas are affected by high chemical oxygen demand (COD and biological oxygen demand (BOD5 concentrations, due to intensive farming activities and runoff. Practical cases have shown that constructed wetlands (CWs are eco-friendly and cost-effective treatment systems which can reduce high levels of organic and nutrient pollution from agricultural discharges. However, accumulated recalcitrant organic matter, originated by in-situ sources or elements of CWs (i.e., plants or microbial detritus, limits the fulfilment of current COD discharge threshold. Thus, to evaluate its relevance regarding rivers ecosystem health preservation, we analysed the response of bio-indicators, the Multimetric Macroinvertebrate Index Flanders (MMIF and the occurrence of organic pollution sensitive taxa towards organic pollutants. For this purpose, statistical models were developed based on collected data in polder watercourses and CWs located in Flanders (Belgium. Results showed that, given the correlation between COD and BOD5, both parameters can be used to indicate the ecological and water quality conditions. However, the variability of the MMIF and the occurrence of sensitive species are explained better by BOD5, which captures a major part of their common effect. Whereas, recalcitrant COD and the interaction among other physico-chemical variables indicate a minor variability on the bio-indicators. Based on these outcomes we suggest a critical re-evaluation of current COD thresholds and moreover, consider other emerging technologies determining organic pollution levels, since this could support the feasibility of the implementation of CWs to tackle agricultural pollution.
Performance of the constructed wetland system for the treatment of water from the corumbataí river
Ana Kleiber Pessoa Borges
Full Text Available The aim of this work was to study the constructed wetland system for the treatment of water from the Corumbataí river simulated on a laboratory scale. The parameters analyzed at different points of the system were ammonia, biochemical demand for oxygen (BDO, chemical demand for oxygen (CDO, chlorides, apparent color, conductivity, dissolved oxygen, magnesium (Mg, sodium (Na, potassium (K, silicon (Si, total phosphorous, total coliforms and Escherichia coli, total dissolved solids (TDS, turbidity, and macrophyte biomass. The results demonstrated that this alternative water treatment system was effective in removing the microorganisms (total coliforms and E. coli, among other parameters analyzed, for varying periods of the treatment, promoting notable improvement in the quality of the water treated from the Corumbataí River.Na intenção de reduzir nutrientes e microrganismos das águas de rio, foi estudado um processo alternativo de tratamento, como o sistema construído de áreas alagadas (CWs, em escala de laboratório. Os parâmetros analisados em diferentes pontos do sistema utilizado foram amônia, demanda bioquímica de oxigênio (DBO, demanda química de oxigênio (DQO, cloretos, cor aparente, condutividade, oxigênio dissolvido, magnesium (Mg, sodium (Na, potassium (K, silicium (Si, fósforo total, coliformes totais e Escherichia coli, sólidos totais dissolvidos (TDS, turbidez e biomassa da macrófita. Os resultados demonstraram que este sistema alternativo de tratamento de água do rio Corumbataí foi eficiente na remoção dos microrganismos: coliformes totais e Escherichia coli dentre outros parâmetros analisados, em diferentes tempos de tratamento, promovendo melhoria acentuada na qualidade da água tratada.
Validity of manganese as a surrogate of heavy metals removal in constructed wetlands treating acidic mine water
Royer, E.; Unz, R.F.; Hellier, W.W.
The evaluation of manganese as a surrogate for heavy metal behavior in two wetland treatment systems receiving acidic coal mine drainage in central Pennsylvania was investigated. The use of manganese as an indicator is based on physical/chemical treatment processes quite different from wetland treatment. The treatment systems represented one anoxic, subsurface flow system and one oxic surface flow system. Water quality parameters measured included pH, alkalinity, acidity, and a suite of metals. Correlation and linear regression analysis were used to evaluate the ability of a candidate predictor variable (indicator) to predict heavy metal concentrations and removal. The use of manganese as a predictor of effluent quality proved to be poor in both wetland treatment systems, as evidenced by low linear R 2 values and negative correlations. Zinc emerged as the best predictor of the detectable heavy metals at the anoxic wetland. Zinc exhibited positive strong linear correlations with copper, cobalt, and nickel (R 2 values of 0.843, 0.881, and 0.970, respectively). Effluent pH was a slightly better predictor of effluent copper levels in the anoxic wetland. Iron and cobalt effluent concentrations showed the only strong relationship (R 2 value = 0.778) in the oxic system. The lack of good correlations with manganese strongly challenges its appropriateness as a surrogate for heavy metals in these systems
Using Tradtional Ecological Knowledge to Protect Wetlands: the Swinomish Tribe's Wetland Cultural Assessment Project
Mitchell, T.
"Traditional" wetland physical assessment modules do not adequately identify Tribal cultural values of wetlands and thus wetlands may not be adequately protected for cultural uses. This Swinomish Wetlands Cultural Assessment Project has developed a cultural resource scoring module that can be incorporated into wetland assessments to better inform wetland protections. Local native knowledge was gathered about the traditional uses of 99 native wetland plant species. A cultural scoring matrix was developed based on the presence of traditionally used plants in several use categories including: construction, ceremonial, subsistence, medicinal, common use, plant rarity, and place of value for each wetland. The combined score of the cultural and physcial modules provides an overall wetland score that relates to proscribed buffer protection widths. With this local native knowledge incorporated into wetland assessments, we are protecting and preserving Swinomish Reservation wetlands for both cultural uses and ecological functionality through the Tribe's wetland protection law.
A Point Source of a Different Color: Identifying a Gap in United States Regulatory Policy for "Green� CSO Treatment Using Constructed Wetlands
Zeno F. Levy
Full Text Available Up to 850 billion gallons of untreated combined sewer overflow (CSO is discharged into waters of the United States each year. Recent changes in CSO management policy support green infrastructure (GI technologies as "front of the pipe� approaches to discharge mitigation by detention/reduction of urban stormwater runoff. Constructed wetlands for CSO treatment have been considered among suites of GI solutions. However, these wetlands differ fundamentally from other GI technologies in that they are "end of the pipe� treatment systems that discharge from a point source, and are therefore regulated in the U.S. under the National Pollution Discharge Elimination System (NPDES. We use a comparative regulatory analysis to examine the U.S. policy framework for CSO treatment wetlands. We find in all cases that permitting authorities have used best professional judgment to determine effluent limits and compliance monitoring requirements, referencing technology and water quality-based standards originally developed for traditional "grey� treatment systems. A qualitative comparison with Europe shows less stringent regulatory requirements, perhaps due to institutionalized design parameters. We recommend that permitting authorities develop technical guidance documents for evaluation of "green� CSO treatment systems that account for their unique operational concerns and benefits with respect to sustainable development.
A review on the application of constructed wetlands for the removal of priority substances and contaminants of emerging concern listed in recently launched EU legislation
Gorito, Ana M.; Ribeiro, Ana R.; Almeida, C.M.R.; Silva, Adrián M.T.
The presence of organic pollutants in the aquatic environment, usually found at trace concentrations (i.e., between ng L −1 and μg L −1 or even lower, known as micropollutants), has been highlighted in recent decades as a worldwide environmental concern due to their difficult elimination by conventional water and wastewater treatment processes. The relevant information on constructed wetlands (CWs) and their application for the removal of a specific group of pollutants, 41 organic priority substances/classes of substances (PSs) and 8 certain other substances with environmental quality standards (EQS) listed in Directive 2013/39/EU as well as 17 contaminants of emerging concern (CECs) of the Watch List of Decision 2015/495/EU, is herein reviewed. Studies were found for 24 PSs and 2 other substances with EQS: octylphenol, nonylphenol, perfluorooctane sulfonic acid, di(2-ethylhexyl)phthalate, trichloromethane, dichloromethane, 1,2-dichloroethane, pentachlorobenzene, benzene, polychlorinated dibenzo-p-dioxins, naphthalene, fluoranthene, trifluralin, alachlor, isoproturon, diuron, tributyltin compounds, simazine, atrazine, chlorpyrifos (chlorpyrifos-ethyl), chlorfenvinphos, hexachlorobenzene, pentachlorophenol, endosulfan, dichlorodiphenyltrichloroethane (or DDT) and dieldrin. A few reports were also published for 8 CECs: imidacloprid, erythromycin, clarithromycin, azithromycin, diclofenac, estrone, 17-beta-estradiol and 17-alpha-ethinylestradiol. No references were found for the other 17 PSs, 6 certain other substances with EQS and 9 CECs listed in EU legislation. - Highlights: • Directive 2013/39/EU includes 41 organic priority substances/classes of substances. • Watch List of Decision 2015/495/EU defines 17 contaminants of emerging concern. • Removal of these water micropollutants by constructed wetlands (CWs) is reviewed. • The need to study removal by CWs of more of these substances is emphasized. • More works with realistic concentrations
Performance of different substrates in constructed wetlands planted with E. crassipes treating low-strength sewage under subtropical conditions.
Lima, M X; Carvalho, K Q; Passig, F H; Borges, A C; Filippe, T C; Azevedo, J C R; Nagalli, A
The present study aimed to assess removal potential of chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total ammonia nitrogen (TAN), total phosphorus (TP) and acetylsalicylic acid (ASA) in synthetic wastewater simulating low-strength sewage by sequencing-batch mode constructed wetlands (CWs). Six CWs with three substrates (gravel, light expanded clay and clay bricks) and one CW of each substrate was planted with E. crassipes to verify the feasibility of using a floating macrophyte in CWs and verify the best optimized substrate. Results showed that the presence of E. crassipes enhanced the removal of COD for systems with gravel, increasing the removal efficiency from 37% in the unplanted system (CW G-U ) to 60% in the planted system (CW G-P ). The vegetated CW with clay bricks (CW B-P ) presented the best performance for both TKN and TAN removal, with maximum removal efficiencies of 68% and 35%, respectively. Phosphorus was observed to be efficiently removed in systems with clay bricks, both planted (CW B-U ) and unplanted (CW B-P ), with mean removal efficiencies of 82% and 87%, respectively, probably via adsorption. It was also observed that after 296days of operation, no desorption or increase on phosphorus in effluent samples were observed, thus indicating that the material was not yet saturated and phosphorus probably presents a strong binding to the media. ASA removal efficiency varied from 34% to 92% in CWs, probably due to plant uptake through roots and microbial biodegradation. Plant direct uptake varied from 4 to 74% of the total nitrogen and from 26 to 71% of the total phosphorus removed in CW G-P , CW C-P and CW B-P . E. crassipes was able to uptake up to 4.19g of phosphorus in CW C-P and 11.84g of nitrogen in CW B-P . The findings on this study suggest that E. crassipes could be used in CWs and clay bricks could significantly enhance phosphorus removal capacity in CWs. Copyright © 2018 Elsevier B.V. All rights reserved.
Removal of selected emerging PPCP compounds using greater duckweed (Spirodela polyrhiza) based lab-scale free water constructed wetland.
Li, Jianan; Zhou, Qizhi; Campos, Luiza C
Greater duckweed (Spirodela polyrhiza) based lab-scale free water constructed wetland (CW) was employed for removing four emerging pharmaceuticals and personal care products (PPCPs) (i.e. DEET, paracetamol, caffeine and triclosan). Orthogonal design was used to test the effect of light intensity, aeration, E.coli abundance and plant biomass on the target compounds. Synthetic wastewater contaminated with the target compounds at concentration of 25 μg/L was prepared, and both batch and continuous flow experiments were conducted. Up to 100% removals were achieved for paracetamol (PAR), caffeine (CAF) and tricolsan (TCS) while the highest removal for DEET was 32.2% in batch tests. Based on orthogonal Duncan analysis, high light intensity (240 μmolmm -2 s -1 ), full aeration, high plant biomass (1.00 kg/m 2 ) and high E.coli abundance (1.0 × 10 6  CFU/100 mL) favoured elimination of the PPCPs. Batch verification test achieved removals of 17.1%, 98.8%, 96.4% and 95.4% for DEET, PAR, CAF and TCS respectively. Continuous flow tests with CW only and CW followed by stabilization tank (CW-ST) were carried out. Final removals of the PPCP contaminants were 32.6%, 97.7%, 98.0% and 100% for DEET, PAR, CAF and TCS, respectively, by CW system alone, while 43.3%, 97.5%, 98.2% and 100%, respectively, were achieved by CW-ST system. By adding the ST tank, PPCP concentrations decreased significantly faster (p <50%) and high E.coli abundance (up to 1.7 log increase) in the final treated water indicated further treatment processes may be required. Statistical analysis showed significant correlations
Large-scale multi-stage constructed wetlands for secondary effluents treatment in northern China: Carbon dynamics.
Wu, Haiming; Fan, Jinlin; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan
Multi-stage constructed wetlands (CWs) have been proved to be a cost-effective alternative in the treatment of various wastewaters for improving the treatment performance as compared with the conventional single-stage CWs. However, few long-term full-scale multi-stage CWs have been performed and evaluated for polishing effluents from domestic wastewater treatment plants (WWTP). This study investigated the seasonal and spatial dynamics of carbon and the effects of the key factors (input loading and temperature) in the large-scale seven-stage Wu River CW polishing domestic WWTP effluents in northern China. The results indicated a significant improvement in water quality. Significant seasonal and spatial variations of organics removal were observed in the Wu River CW with a higher COD removal efficiency of 64-66% in summer and fall. Obvious seasonal and spatial variations of CH 4 and CO 2 emissions were also found with the average CH 4 and CO 2 emission rates of 3.78-35.54 mg m -2 d -1 and 610.78-8992.71 mg m -2 d -1 , respectively, while the higher CH 4 and CO 2 emission flux was obtained in spring and summer. Seasonal air temperatures and inflow COD loading rates significantly affected organics removal and CH 4 emission, but they appeared to have a weak influence on CO 2 emission. Overall, this study suggested that large-scale Wu River CW might be a potential source of GHG, but considering the sustainability of the multi-stage CW, the inflow COD loading rate of 1.8-2.0 g m -2 d -1 and temperature of 15-20 °C may be the suitable condition for achieving the higher organics removal efficiency and lower greenhouse gases (GHG) emission in polishing the domestic WWTP effluent. The obtained knowledge of the carbon dynamics in large-scale Wu River CW will be helpful for understanding the carbon cycles, but also can provide useful field experience for the design, operation and management of multi-stage CW treatments. Copyright © 2017 Elsevier Ltd. All rights
Diurnal dynamics of oxygen and carbon dioxide concentrations in shoots and rhizomes of a perennial in a constructed wetland indicate down-regulation of below ground oxygen consumption
Fausser, A. C.; Dušek, Jiří; Čížková, Hana; Kazda, M.
Ro�. 8, JUL (2016), �. �lánku plw025. ISSN 2041-2851 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk(CZ) LM2010007 Institutional support: RVO:86652079 Keywords : typha-latifolia l * internal gas-transport * phragmites-australis * convective throughflow * pressurized ventilation * angustifolia l * ex steud * roots * flow * respiration * Aeration * constructed wetland * in-situ field study * internal carbon dioxide * internal oxygen dynamics * Phragmites australis Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.238, year: 2016
Indicators of early successional trends in environmental condition and community function in constructed wetlands of the Athabasca Oilsands region
Ciborowski, J.; Kovalenko, K. [Windsor Univ., ON (Canada); Dixon, G.; Farwell, A. [Waterloo Univ., ON (Canada); Foote, L.; Mollard, F.; Roy, M. [Alberta Univ., Edmonton, AB (Canada); Smits, J.; Turcotte, D. [Saskatchewan Univ., Saskatoon, SK (Canada)
This presentation reported on a study that compared interannual environmental variation in post-mining Athabasca oil sands landscapes. In particular, it compared biological, ecotoxicological and carbon dynamic aspects of sixteen 5 to 30 year old wetlands with different ages, reclamation materials and stockpiled surface materials such as peat. In addition to determining carbon fluxes, standing stocks of hydrocarbons were measured along with organic substrate, bacterioplankton, phytoplankton, biofilm, macrophytes, litter, zoobenthos, and aquatic insect emergence. Gas fluxes, microbial, plant, zoobenthic, amphibian, and tree swallow nestling production, and stable isotope signatures were used to determine carbon pathways, fluxes and budgets. Coarse taxon richness in reference wetlands reached an asymptote in 5 to 7 years. Richness, composition and emergent plant cover of oilsands-affected wetlands converged over a 15 to 20 year period with reference wetland patterns. The development of emergent but not submergent plant cover and associated biota accelerated with the addition of peat. Water chemistry was found to be more important than sediment in terms of regulating submergent biological properties. The study showed that the most important regulator of community composition may be residual salinity. Compared to more temperate biomes, the successional trends were slower.
PERFORMANCE OF A SURFACE FLOW CONSTRUCTED WETLAND SYSTEM USED TO TREAT SECONDARY EFFLUENT AND FILTER BACKWASH WATER
Juan Antonio Vidales-Contreras
The performance of a surface flow wetland system used to treat activated sludge effluent and filter backwash water from a tertiary treatment facility was evaluated. Samples were collected before and after vegetation removal from the system which consists of two densely vegetated settling basins (0.35 ha, an artificial stream, and a 3-ha surface flow wetland. Bulrush (Scripus spp. and cattail (Typha domingensis were the dominant plant species. The average inflow of chlorinated secondary effluent during the first two months of the actual study was 1.9 m3 min-1 while the inflow for backwash water treatment ranged from 0.21 to 0.42 m3 min-1. The system was able to reduce TSS and BOD5 to tertiary effluent standards; however, monitoring of chloride concentrations revealed that wetland evapotranspiration is probably enriching pollutant concentrations in the wetland outflow. Coliphage removal from the filter backwash was 97 and 35% during 1999 and 2000, respectively. However, when secondary effluent entered the system, coliphage removal averaged 65%. After vegetation removal, pH and coliphage density increased significantly (p
A Preliminary System Dynamics Model of a Constructed Wetland for the Mitigation of Metals in USAF Storm Water
Cultivated Land Grassland 0 500 1000 1500 2000 (Technology Review, 1994:23) The Scientific American article continues with the benefits provided by...34 Ecotoxicology and Wetland Ecosystems: Current Understanding and Future Needs," Environmental Toxicology and Chemistry. Volume 12, pp 2209-2224, 1993
Ciborowski, J.; Kovalenko, K.; Dixon, G.; Farwell, A.; Foote, L.; Mollard, F.; Roy, M.; Smits, J.; Turcotte, D.
Treating runoff in the construction and operational phases of a greenfield development using floating wetland treatment systems
Walker, Christopher; Lucke, Terry; Boogaard, Floris; Schwammberger, Peter
Floating wetland treatment systems (FWTS) are an innovative stormwater treatment technology currently being trialled on a larger scale in Australia. FWTS provide support for selected plant species to remove pollutants from stormwater discharged into a water body. The plant roots provide large
Removal and distribution of iron, manganese, cobalt and nickel within a Pennsylvania constructed wetland treating coal combustion by-product leachate
Ye, Z.H.; Whiting, S.N.; Lin, Z.-Q.; Lytle, C.M.; Qian, J.H.; Terry, N. [University of California, Berkeley, CA (USA). Dept. of Plant and Microbial Biology
A flow-through wetland treatment system was constructed to treat coal combustion by-product leachate from an electrical power station at Springdale, Pennsylvania. In a nine-compartment treatment system, four cattail (Typha latifolia L.) wetland cells (designated Cells 1 through 4) successfully removed iron (Fe) and manganese (Mn) from the inlet water; Fe and Mn concentrations were decreased by an average of 91% in the first year and by 94 and 98% in the second year respectively. Cobalt (Co) and nickel (Ni) were decreased by an average of 39 and 47% in the first and 98 and 63% in the second year respectively. Most of the metal removed by the wetland cells was accumulated in sediments, which constituted the largest sink. Except for Fe, metal concentrations in the sediments tended to be greater in the top 5 cm of sediment than in the 5 to 10 or 10 to 15 cm layers and in Cell 1 than in Cells 2, 3 and 4. Plants constituted a much smaller sink for metals; only 0.91, 4.18, 0.19, and 0.38% of the Fe, Mn, Co and Ni were accumulated annually in the aboveground tissues of cattail, respectively. A greater proportion of each metal (except Mn) was accumulated in cattail fallen litter and submerged Chara (a macroalga) tissues, that is 2.81, 2.75 and 1.05% for Fe, Co and Ni, respectively. Considerably higher concentrations of metals were associated with cattail root than shoots, although Mn was a notable exception. 48 refs., 6 figs., 4 tabs.
Mercury, monomethyl mercury, and dissolved organic carbon concentrations in surface water entering and exiting constructed wetlands treated with metal-based coagulants, Twitchell Island, California
Stumpner, Elizabeth B.; Kraus, Tamara E.C.; Fleck, Jacob A.; Hansen, Angela M.; Bachand, Sandra M.; Horwath, William R.; DeWild, John F.; Krabbenhoft, David P.; Bachand, Philip A.M.
Coagulation with metal-based salts is a practice commonly employed by drinking-water utilities to decrease particle and dissolved organic carbon concentrations in water. In addition to decreasing dissolved organic carbon concentrations, the effectiveness of iron- and aluminum-based coagulants for decreasing dissolved concentrations both of inorganic and monomethyl mercury in water was demonstrated in laboratory studies that used agricultural drainage water from the Sacramento–San Joaquin Delta of California. To test the effectiveness of this approach at the field scale, nine 15-by-40‑meter wetland cells were constructed on Twitchell Island that received untreated water from island drainage canals (control) or drainage water treated with polyaluminum chloride or ferric sulfate coagulants. Surface-water samples were collected approximately monthly during November 2012–September 2013 from the inlets and outlets of the wetland cells and then analyzed by the U.S. Geological Survey for total concentrations of mercury and monomethyl mercury in filtered (less than 0.3 micrometers) and suspended-particulate fractions and for concentrations of dissolved organic carbon.
Nitrogen removal and nitrous oxide emission in surface flow constructed wetlands for treating sewage treatment plant effluent: Effect of C/N ratios.
Li, Ming; Wu, Haiming; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Kong, Qiang
In order to design treatment wetlands with maximal nitrogen removal and minimal nitrous oxide (N 2 O) emission, the effect of influent C/N ratios on nitrogen removal and N 2 O emission in surface flow constructed wetlands (SF CWs) for sewage treatment plant effluent treatment was investigated in this study. The results showed that nitrogen removal and N 2 O emission in CWs were significantly affected by C/N ratio of influent. Much higher removal efficiency of NH 4 + -N (98%) and TN (90%) was obtained simultaneously in SF CWs at C/N ratios of 12:1, and low N 2 O emission (8.2mg/m 2 /d) and the percentage of N 2 O-N emission in TN removal (1.44%) were also observed. These results obtained in this study would be utilized to determine how N 2 O fluxes respond to variations in C/N ratios and to improve the sustainability of CWs for wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.
Seasonality distribution of the abundance and activity of nitrification and denitrification microorganisms in sediments of surface flow constructed wetlands planted with Myriophyllum elatinoides during swine wastewater treatment.
Li, Xi; Zhang, Miaomiao; Liu, Feng; Chen, Liang; Li, Yuyuan; Li, Yong; Xiao, Rulin; Wu, Jinshui
Surface flow constructed wetlands (SFCWs) planted with Myriophyllum elatinoides for treatment of swine wastewater were examined to evaluate the effect of season, segment (site S1, S2, and S3), and treatment (100mgL -1 TN, T1; 300mgL -1 TN, T2; 500mgL -1 TN, T3) on the activity, and abundances of nitrifying and, denitrifying microorganisms, and on the abundance of sediment bacteria. The activity and abundances of nitrifiers, denitrifiers, and the abundance of bacteria were the highest in T3 samples, especially in S1 (Pswine wastewater treatment stimulate the growth of nitrifiers, denitrifiers and bacteria in sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.
Influences of seasons, N/P ratios and chemical compounds on phosphorus removal performance in algal pond combined with constructed wetlands.
Zhimiao, Zhao; Xinshan, Song; Yanping, Xiao; Yufeng, Zhao; Zhijie, Gong; Fanda, Lin; Yi, Ding; Wei, Wang; Tianling, Qin
Nitrogen (N) and phosphorous (P) are main contaminants and P removal was restrained by several factors: season, N/P, and chemical compounds (CCs) in water ecosystems. In this paper, two algal ponds combined with constructed wetlands were built to increase the removal performance. Different hydraulic retention time (HRT), different N/P and chemical compounds were chosen to investigate the influences of the above factors on the contaminant removal performance. The optimum phosphorus removal rate was 69.74% under the nitrogen removal of 92.85% in influent containing PO 4 3- after 3-day HRT in algal pond combined with constructed wetlands. The investigation results indicated that these factors improved the nutrient removal efficiencies. Seasonal influence on the removal performance can be avoided by choosing the optimal HRT length of 3days. The higher N/P at 60 can improve the phosphorus removal and the lower N/P at 15 showed the stronger synergistic effect between phosphorus and nitrogen removals. Compared with PO 3 - and P 2 O 7 4- in influent, PO 4 3- affected phosphorus removal more significantly. The better linear fitting between organic phosphorus removal and nitrogen removal in influent contained P 2 O 7 4- was found. Algae can absorb nutrients for growth, and oxygen release, microbial activity intensification and microbial carbon replenishment induced by algae will improve the performance. The study suggested that the control of HRTs, N/Ps, CCs, and algae might be an effective way to improve wastewater treatment performance. Copyright © 2016 Elsevier B.V. All rights reserved.
Importance of Macrophyte Quality in Determining Life-History Traits of the Apple Snails Pomacea canaliculata: Implications for Bottom-Up Management of an Invasive Herbivorous Pest in Constructed Wetlands
Rita S. W. Yam
Full Text Available Pomacea canaliculata (Ampullariidae has extensively invaded most Asian constructed wetlands and its massive herbivory of macrophytes has become a major cause of ecosystem dysfunctioning of these restored habitats. We conducted non-choice laboratory feeding experiments of P. canaliculata using five common macrophyte species in constructed wetlands including Ipomoea aquatica, Commelina communis, Nymphoides coreana, Acorus calamus and Phragmites australis. Effects of macrophytes on snail feeding, growth and fecundity responses were evaluated. Results indicated that P. canaliculata reared on Ipomoea had the highest feeding and growth rates with highest reproductive output, but all individuals fed with Phragmites showed lowest feeding rates and little growth with poorest reproductive output. Plant N and P contents were important for enhancing palatability, supporting growth and offspring quantity of P. canaliculata, whilst toughness, cellulose and phenolics had critically deterrent effects on various life-history traits. Although snail offspring quality was generally consistent regardless of maternal feeding conditions, the reduced growth and offspring quantity of the poorly-fed snails in constructed wetlands dominated by the less-palatable macrophytes could limit the invasive success of P. canaliculata. Effective bottom-up control of P. canaliculata in constructed wetlands should involve selective planting strategy using macrophytes with low nutrient and high toughness, cellulose and phenolic contents.
Importance of Macrophyte Quality in Determining Life-History Traits of the Apple Snails Pomacea canaliculata: Implications for Bottom-Up Management of an Invasive Herbivorous Pest in Constructed Wetlands.
Yam, Rita S W; Fan, Yen-Tzu; Wang, Tzu-Ting
Pomacea canaliculata (Ampullariidae) has extensively invaded most Asian constructed wetlands and its massive herbivory of macrophytes has become a major cause of ecosystem dysfunctioning of these restored habitats. We conducted non-choice laboratory feeding experiments of P. canaliculata using five common macrophyte species in constructed wetlands including Ipomoea aquatica, Commelina communis, Nymphoides coreana, Acorus calamus and Phragmites australis. Effects of macrophytes on snail feeding, growth and fecundity responses were evaluated. Results indicated that P. canaliculata reared on Ipomoea had the highest feeding and growth rates with highest reproductive output, but all individuals fed with Phragmites showed lowest feeding rates and little growth with poorest reproductive output. Plant N and P contents were important for enhancing palatability, supporting growth and offspring quantity of P. canaliculata, whilst toughness, cellulose and phenolics had critically deterrent effects on various life-history traits. Although snail offspring quality was generally consistent regardless of maternal feeding conditions, the reduced growth and offspring quantity of the poorly-fed snails in constructed wetlands dominated by the less-palatable macrophytes could limit the invasive success of P. canaliculata. Effective bottom-up control of P. canaliculata in constructed wetlands should involve selective planting strategy using macrophytes with low nutrient and high toughness, cellulose and phenolic contents.
Yam, Rita S. W.; Fan, Yen-Tzu; Wang, Tzu-Ting
Pomacea canaliculata (Ampullariidae) has extensively invaded most Asian constructed wetlands and its massive herbivory of macrophytes has become a major cause of ecosystem dysfunctioning of these restored habitats. We conducted non-choice laboratory feeding experiments of P. canaliculata using five common macrophyte species in constructed wetlands including Ipomoea aquatica, Commelina communis, Nymphoides coreana, Acorus calamus and Phragmites australis. Effects of macrophytes on snail feeding, growth and fecundity responses were evaluated. Results indicated that P. canaliculata reared on Ipomoea had the highest feeding and growth rates with highest reproductive output, but all individuals fed with Phragmites showed lowest feeding rates and little growth with poorest reproductive output. Plant N and P contents were important for enhancing palatability, supporting growth and offspring quantity of P. canaliculata, whilst toughness, cellulose and phenolics had critically deterrent effects on various life-history traits. Although snail offspring quality was generally consistent regardless of maternal feeding conditions, the reduced growth and offspring quantity of the poorly-fed snails in constructed wetlands dominated by the less-palatable macrophytes could limit the invasive success of P. canaliculata. Effective bottom-up control of P. canaliculata in constructed wetlands should involve selective planting strategy using macrophytes with low nutrient and high toughness, cellulose and phenolic contents. PMID:26927135
Are outbreaks of emerging pathogens correlated with construction of wetlands? Report 2 : amphibian breeding and disease outbreaks during 2014-2015 and possible correlates with environmental variables : research report.
A study of wetlands near the Intercounty Connector construction site (now a toll facility MD 200) in Maryland, : found that an emerging pathogen known as Ranavirus was having a significant impact on at least two species of : amphibians as well as...
Macrophyte decomposition in a surface-flow ammonia-dominated constructed wetland: Rates associated with environmental and biotic variables
Thullen, J.S.; Nelson, S.M.; Cade, B.S.; Sartoris, J.J.
Decomposition of senesced culm material of two bulrush species was studied in a surface-flow ammonia-dominated treatment wetland in southern California. Decomposition of the submerged culm material during summer months was relatively rapid (k = 0.037 day-1), but slowed under extended submergence (up to 245 days) and during fall and spring sampling periods (k = 0.009-0.014 day-1). Stepwise regression of seasonal data indicated that final water temperature and abundance of the culm-mining midge, Glyptotendipes, were significantly associated with culm decomposition. Glyptotendipes abundance, in turn, was correlated with water quality parameters such as conductivity and dissolved oxygen and ammonia concentrations. No differences were detected in decomposition rates between the bulrush species, Schoenoplectus californicus and Schoenoplectus acutus.
76 FR 79145 - Floodplain Management and Protection of Wetlands
...] RIN 2501-AD51 Floodplain Management and Protection of Wetlands Correction In proposed rule document... Type of proposed action Type of proposed action (new Wetlands or 100- Non-wetlands area reviewable... construction in wetlands locations. \\2\\ Or those paragraphs of Sec. 55.20 that are applicable to an action...
Pollutant removal performance of an integrated upflow-constructed wetland filled with haydites made of Al-based drinking water treatment residuals.
Wang, Wendong; Han, Yu; Liu, Hui; Zhang, Ke; Yue, Qiang; Bo, Longli; Wang, Xiaochang
This study examined the pollutants removal performance of an integrated upflow-constructed wetland (IUCW) system in a 1.5 years' continuous operation. The average concentrations of chemical oxygen demand (COD), NH 4 -N, total nitrogen (TN), and total phosphorus (TP) in the effluent were 21.9, 1.47, 2.63, and 0.18 mg/L, respectively, which corresponded to 90.1%, 23.3%, 86.1%, and 97.2% removals from the raw water, respectively. The residual concentration of COD was 219 mg/L at start-up and decreased notably to 52.8 mg/L after 50 days of operation. NH 4 -N was difficult to remove because the average concentration of dissolved oxygen in the IUCW system was lower than 0.6 mg/L. In contrast, the residual concentrations of both TN and TP in the effluent were stable, with average removal rates as high as 89% and 99%, respectively, at start-up of the system. Changing the organic loading rates from 45.0 g/(m 2 ·day) to 20.0 or 60.0 g/(m 2 ·day) both inhibited the removal of TN. Further study showed that the removal of organic matter mainly occurred within 10-20 cm of the wetland cell. Considering its strong organic, nitrogen, and phosphate removal capacity, the IUCW system was determined to be effective in decentralized wastewater treatment.
Use of N Natural Abundance and N Species Concentrations to Assess N-Cycling in Constructed and Natural Coastal Wetlands
C. Marjorie Aelion
Full Text Available Natural abundance of N stable isotopes used in combination with concentrations may be useful indicators of N-cycling in wetlands. Concentrations and N signatures of NO3−, NH4+, and sediment organic nitrogen (SON were measured in two impacted coastal golf course retention ponds and two natural marshes. Limited NO3− was detected in natural site surface water or pore water, but both isotopic signature and concentrations of NO3− in surface water of impacted sites indicated anthropogenic inputs. In natural sites, NH4+ concentrations were greatest in deeper pore water and least in surface water, suggesting diffusion predominates. The natural sites had greater %SON, and N indicated that the natural sites also had greater NH4+ released from SON mineralization than impacted sites. In NO3−-limited systems, neither concentrations nor N natural abundance was able to provide information on N-cycling, while processes associated with NH4+ were better elucidated by using both concentrations and N natural abundance.
The potential use of storm water and effluent from a constructed wetland for re-vegetating a degraded pyrite trail in Queen Elizabeth National Park, Uganda
Osaliya, R.; Kansiime, F.; Oryem-Origa, H.; Kateyo, E.
During the operation of the Kilembe Mines (copper mining) a cobaltiferous stockpile was constructed, which began to erode after the closure of the mines in the early 1970s. The erosion of the pyrite stockpile resulted in a large acid trail all the way to Lake George (a Ramsar site). The acid trail contaminated a large area of Queen Elizabeth National Park (QENP) resulting in the death of most of the shallow-rooted vegetation. Processes and conditions created by storm water and effluent from a constructed wetland were assessed for vegetation regeneration in the degraded QENP pyrite trail. Cynodon dactylon, Imperata cylindrica and Hyparrhenia filipendula dominated the regeneration zone (RZ) where storm water and effluent from a constructed wetland was flowing; and the adjacent unpolluted area (UP) with importance value indices of 186.4 and 83.3 respectively. Typha latifolia and C. dactylon formed two distinct vegetation sub-zones within the RZ with the former inhabiting areas with a higher water table. Soil pH was significantly higher in the RZ, followed by UP and bare pyrite trail (BPT) at both 0-15 cm and 16-30 cm depths. Soil electrical conductivity was not significantly different in the RZ and BPT but significantly higher than that in UP for both depths. For 0-15 cm depth, RZ had significantly higher concentrations of copper than BPT and UP which had similar concentrations. Still at this depth (0-15 cm), the unpolluted area had significantly higher concentrations of total phosphorus and total nitrogen than the regeneration zone and the bare pyrite trail which had similar concentrations. The RZ dominated by Typha had significantly higher concentrations of TP and TN compared to the RZ dominated by Cynodon. The concentrations of NH 4-N were significantly lower in Typha regeneration zone than in CRZ at 0-15 cm depth but similar at 16-30 cm depth. At 16-30 cm depth, concentrations of copper were significantly higher in the regeneration zone followed by the bare pyrite
Wetland Hydrology
This chapter discusses the state of the science in wetland hydrology by touching upon the major hydraulic and hydrologic processes in these complex ecosystems, their measurement/estimation techniques, and modeling methods. It starts with the definition of wetlands, their benefit...
The nitrogen abatement cost in wetlands
Bystroem, Olof
The costs of abating agricultural nitrogen pollution in wetlands are estimated. By linking costs for construction of wetlands to the denitrification capacity of wetlands, an abatement cost function can be formed. A construction-cost function and a denitrification function for wetlands is estimated empirically. This paper establishes a link between abatement costs and the nitrogen load on wetlands. Since abatement costs fluctuate with nitrogen load, ignoring this link results in incorrect estimates of abatement costs. The results demonstrate that wetlands have the capacity to provide low cost abatement of nitrogen compounds in runoff. For the Kattegatt region in Sweden, marginal abatement costs for wetlands are shown to be lower than costs of land use changing measures, such as extended land under fallow or cultivation of fuel woods, but higher than the marginal costs of reducing nitrogen fertilizer
Horizontal Accelerator
Federal Laboratory Consortium — The Horizontal Accelerator (HA) Facility is a versatile research tool available for use on projects requiring simulation of the crash environment. The HA Facility is...
Contribution of water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutrient conditions to Fe-removal mechanisms in constructed wetlands.
Jayaweera, Mahesh W; Kasturiarachchi, Jagath C; Kularatne, Ranil K A; Wijeyekoon, Suren L J
Severe contamination of water resources including groundwater with iron (Fe) due to various anthropogenic activities has been a major environmental problem in industrial areas of Sri Lanka. Hence, the use of the obnoxious weed, water hyacinth (Eichhornia crassipes (Mart.) Solms) in constructed wetlands (floating aquatic macrophyte-based plant treatment systems) to phytoremediate Fe-rich wastewaters seems to be an appealing option. Although several studies have documented that hyacinths are good metal-accumulating plants none of these studies have documented the ability of this plant grown under different nutrient conditions to remove heavy metals from wastewaters. This paper, therefore, reports the phytoremediation efficiencies of water hyacinth grown under different nutrient conditions for Fe-rich wastewaters in batch-type constructed wetlands. This study was conducted for 15 weeks after 1-week acclimatization by culturing young water hyacinth plants (average height of 20+/-2cm) in 590L capacity fiberglass tanks under different nutrient concentrations of 1-fold [28 and 7.7mg/L of total nitrogen (TN) and total phosphorous (TP), respectively], 2-fold, 1/2-fold, 1/4-fold and 1/8-fold with synthetic wastewaters containing 9.27Femg/L. Another set-up of hyacinths containing only Fe as a heavy metal but without any nutrients (i.e., 0-fold) was also studied. A mass balance was carried out to investigate the phytoremediation efficiencies and to determine the different mechanisms governing Fe removal from the wastewaters. Fe removal was largely due to phytoremediation mainly through the process of rhizofiltration and chemical precipitation of Fe2O3 and FeOH3 followed by flocculation and sedimentation. However, chemical precipitation was more significant especially during the first 3 weeks of the study. Plants grown in the 0-fold set-up showed the highest phytoremediation efficiency of 47% during optimum growth at the 6th week with a highest accumulation of 6707Femg/kg dry
Engineered wetlands : an innovative environmental solution
Wallace, S.; Davis, B.M. [Jacques Whitford NAWE, White Bear Lake, MN (United States)
Engineered wetlands are now considered as an emerging technology for the in situ remediation of hydrocarbon-contaminated soil and waters. Engineered wetlands incorporate a horizontal subsurface flow gravel bed reactor lined with impermeable liners, and are equipped with forced bed aeration systems in order to enhance oxygen delivery to the wetland's aerobic micro-organisms. The wetlands typically emphasize specific characteristics of wetland ecosystems to improve treatment capacities. This article discussed an engineered wetlands installed at a set of pipeline terminals as well as at a former British Petroleum (BP) refinery. The pipeline terminal generated contact wastewater containing BTEX and ammonia, and a subsurface engineered wetland was built in 1998. To date, the 16,000{sup 2} foot wetland has treated a flow-equalized input of approximately 1.5 m{sup 3} per day of contaminants. At the refinery, a wetland treatment system was designed to treat 6000 m{sup 3} of benzene, toluene, ethylbenzene and xylene (BTEX) and volatile organic compounds (VOCs). The treatment site consists of a golf course, river front trails, and a white water kayak course. A cascade aeration system was used for iron oxidation and air-stripping. A soil matrix biofilter was used for passive gas phase benzene removal, as well as for the removal of ferric hydroxide precipitates. It was concluded that engineered wetlands can offer long-term solutions to site remediation challenges. 1 fig.
Wallace, S.; Davis, B.M.
Engineered wetlands are now considered as an emerging technology for the in situ remediation of hydrocarbon-contaminated soil and waters. Engineered wetlands incorporate a horizontal subsurface flow gravel bed reactor lined with impermeable liners, and are equipped with forced bed aeration systems in order to enhance oxygen delivery to the wetland's aerobic micro-organisms. The wetlands typically emphasize specific characteristics of wetland ecosystems to improve treatment capacities. This article discussed an engineered wetlands installed at a set of pipeline terminals as well as at a former British Petroleum (BP) refinery. The pipeline terminal generated contact wastewater containing BTEX and ammonia, and a subsurface engineered wetland was built in 1998. To date, the 16,000 2 foot wetland has treated a flow-equalized input of approximately 1.5 m 3 per day of contaminants. At the refinery, a wetland treatment system was designed to treat 6000 m 3 of benzene, toluene, ethylbenzene and xylene (BTEX) and volatile organic compounds (VOCs). The treatment site consists of a golf course, river front trails, and a white water kayak course. A cascade aeration system was used for iron oxidation and air-stripping. A soil matrix biofilter was used for passive gas phase benzene removal, as well as for the removal of ferric hydroxide precipitates. It was concluded that engineered wetlands can offer long-term solutions to site remediation challenges. 1 fig
National Wetlands Inventory Lines
Minnesota Department of Natural Resources — Linear wetland features (including selected streams, ditches, and narrow wetland bodies) mapped as part of the National Wetlands Inventory (NWI). The National...
Accumulation of nutrients and heavy metals in Phragmites australis (Cav.) Trin. ex Steudel and Bolboschoenus maritimus (L.) Palla in a constructed wetland of the Venice lagoon watershed
Bragato, Claudia; Brix, Hans; Malagoli, Mario
A recently constructed wetland, located in the Venice lagoon watershed, was monitored to investigate growth dynamics, nutrient and heavy metal shoot accumulation of the two dominating macrophytes: Phragmites australis and Bolboschoenus maritimus. Investigations were conducted over a vegetative season at three locations with different distance to the inlet point to assess effects on vegetation. The distance from the inlet did not affect either shoot biomass or nutrients (N, P, K and Na) and heavy metals (Cr, Ni, Cu and Zn) shoot content. With the exception of Na, nutrient and heavy metal concentrations were higher in shoots of P. australis than in B. maritimus. Heavy metal concentration in the incoming water and in the soil was not correlated to the plant content of either species. Shoot heavy metal concentrations were similar to those reported in the current literature, but accumulation generally increased towards the end of the growing season. - Heavy metal shoot concentration in Phragmites australis and Bolboschoenus maritimus increased significantly at the end of the growing season
Assessment of the technological reliability of a hybrid constructed wetland for wastewater treatment in a mountain eco-tourist farm in Poland.
Jucherski, Andrzej; Nastawny, Maria; Walczowski, Andrzej; Jóźwiakowski, Krzysztof; Gajewska, Magdalena
The aim of the present study was to assess the technological reliability of a domestic hybrid wastewater treatment installation consisting of a classic three-chambered (volume 6 m 3 ) septic tank, a vertical flow trickling bed filled with granules of a calcinated clay material (KERAMZYT), a special wetland bed constructed on a slope, and a permeable pond used as a receiver. The test treatment plant was located at a mountain eco-tourist farm on the periphery of the spa municipality of Krynica-Zdrój, Poland. The plant's operational reliability in reducing the concentration of organic matter, measured as biochemical oxygen demand (BOD 5 ) and chemical oxygen demand (COD), was 100% when modelled by both the Weibull and the lognormal distributions. The respective reliability values for total nitrogen removal were 76.8% and 77.0%, total suspended solids - 99.5% and 92.6%, and PO 4 -P - 98.2% and 95.2%, with the differences being negligible. The installation was characterized by a very high level of technological reliability when compared with other solutions of this type. The Weibull method employed for statistical evaluation of technological reliability can also be used for comparison purposes. From the ecological perspective, the facility presented in the study has proven to be an effective tool for protecting local aquifer areas.
Role of macrophyte and effect of supplementary aeration in up-flow constructed wetland-microbial fuel cell for simultaneous wastewater treatment and energy recovery.
Oon, Yoong-Ling; Ong, Soon-An; Ho, Li-Ngee; Wong, Yee-Shian; Dahalan, Farrah Aini; Oon, Yoong-Sin; Lehl, Harvinder Kaur; Thung, Wei-Eng; Nordin, Noradiba
This study investigates the role of plant (Elodea nuttallii) and effect of supplementary aeration on wastewater treatment and bioelectricity generation in an up-flow const

redpajama_set_name: RedPajamaCommonCrawl