Most water analysis methods quantify individual components. However, some, such as oxygen demand tests quantify an aggregate amount of constituents with a common characteristic. Broadly speaking, BOD and COD quantify amount of oxygen required to oxidize organic matter in water/wastewater to indicate amount of organic material present. BOD utilizes microorganisms to oxidize organic material, while COD uses inorganic chemical oxidant. BOD measurement is the most fundamental way of determining water pollution levels and of predicting possible effects of waste discharge. Organic matter that is present in water can be from plants, sugars, proteins or other substances that enter water film natural sources or pollution. This matter is broken down biochemically by organisms such as bacteria, which can multiply as long as organic matter is present as food and oxygen is available for respiration. If high population of bacteria continuously consume dissolved oxygen in water at an accelerated rate, atmospheric air will not be able to replenish it. This situation can create a lack of dissolved oxygen in water, threatening and destroying many forms of aquatic life. Oxygen depletion in receiving waters has been regarded as an important negative effect of water pollution. Depletion takes place due to microbes consuming organic matter in water via aerobic respiration. This type of respiration uses oxygen as an electron accepter and organic material being consumed provides the energy source. Since O2 content is important for may biological and chemical processes, measurements of amount of O2 actually dissolved in a water sample is of great importance. BOD test relates to amount of O2 that would be required to stabilize waste after discharging to a receiving water body. BOD is a parameter of great concern. Failing to realize importance of BOD in wastewater/effluent treatment systems can lead to devastating effects on local aquatic ecology and quality of underlying groundwater.
Monitoring BOD removal a treatment plant is necessary to verify proper operation. BOD test is typically performed in municipal or industrial wastewater plant. The results of BOD analysis are used to calculate the degree of pollution and to determine the effectiveness of water treatment by waste water and sewage plant. Different organic compounds show different oxygen demand (mg/l), thus the BOD test only gives an approximate idea of the weight of utilizable organic matter. BOD test is carried out using standard methods as prescribed in APHA (Standard Method for the Examination of Water and Wastewater, 20th edn. 5-1-5-6. Baltimore). Test substances and standard substances are dissolved in BOD dilution water. Standard substrate is made of 0.15 mg/l glucose and 0.15 mg/l glutamic acid, which has a calculated BOD of 220 mgL−1. It is expressed in terms of Dissolved Oxygen (DO), which microorganisms, mainly bacteria will consume while degrading organic material in a sample of water under standardized conditions of pH nutrient and microorganisms. The amount of oxygen that dissolves in the water depends on many factors: whether there is adequate time and adequate mixing to fully saturate the water, the water temperature, the air pressure, the salt content of the water, and whether there are substances in the water which consume the O2
Microorganisms either are present in the water sample or are introduced by taking a small quantity of a suitable microbial source such as settled sewage. The inoculants is called BOD ‘seed’ and the process, ‘seeding’. Since BOD analysis relies on a biological process, there is a greater variance in results then would normally be expected in a strictly chemical assay. The Standard methods for the Examination of Water and Wastewater indicated an acceptable range of ±15% at the 200 mg/l level for the reference GGA (Glucose-Glutamic Acid) solution; using the results from a series of Interlaboratory studies.
For all sources of seed, the possibility exists that some wastes will cause poisoning of the microorganisms. Some wastes will have develop3ed microorganisms adapted to the toxic conditions and hence give expected BOD results. But, in other wastes the microorganisms will adapt over the period of the BOD test. Because of the lag time involved in adaptation, a lower BOD is obtained than might be excepted. If the toxicity is sufficiently acute, a zero or close to zero result is obtained. Further, the ratio of various species of bacteria normally added can change in a 5-day period. BOD is the result of a summation of the oxygen demand of these microorganisms, whose contribution to the oxygen demand will change with time because of the changing population and changing feedstock.
Among the major industries in India, Pulp and Paper is one of those that contribute heavily to water pollution. Pollutants that generally arise from the industry include wood sugars, cellulose, fiber, lignin and other spent chemicals, which impart high BOD, COD, color, etc. to the effluent. Thus, there arises a need to develop specific seeding (comprising of selected, acclimatized and autochthonous bacterial strains) for analyzing the BOD load of these industrial wastewaters.
In addition, some of these compounds are refractory to biodegradation because of high molecular weight coupled with lesser bioavailability. The BOD analysis of such types of wastewaters poses acute problems because of many reasons, which include the heterogeneity of the samples from time to time, non-specific microorganisms present in general seeding material and lower biodegradation rate of the organic constituents present therein.
The aforesaid problems can be overcome by formulating a uniform microbial composition comprising selected isolated bacterial strains, acclimatized to pulp and paper wastewater. Further, these bacterial isolates must be specific for biodegradation of organic compounds present in these kinds of wastewater. General seeding materials viz., sewage, Polyseed, Bioseed and BODSEED™, when used for BOD analysis of above said wastewater does not work efficiently because of non-specificity of bacterial strains present therein. This leads to erroneous results, which differ from time to time. On the other hand, if specifically designed formulated microbial consortium comprising selected bacterial strains are used as seed for BOD analysis of above said effluents, it may yield reproducible and reliable results.
Thus, for solving the aforementioned problems, the applicants have realized that there exists a need to provide a process for the preparation of a microbial consortium, specifically formulated for use as seeding material for the BOD analysis of Pulp and paper wastewater.