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Wednesday, May 8, 2019

Date: May 6, 2019Source: Columbia University School of Engineering and Applied ScienceSummary: Researchers report that they have developed a radically different desalination approach--''temperature swing solvent extraction (TSSE)''--for hypersaline brines. Their study demonstrates that TSSE can desalinate very high-salinity brines, up to seven times the concentration of seawater.

This is an illustration describing fresh water production from hypersaline brines by temperature swing solvent extraction.Credit: Chanhee Boo/Columbia Engineering

Hypersaline brines -- water that contains high concentrations of dissolved salts and whose saline levels are higher than ocean water -- are a growing environmental concern around the world. Very challenging and costly to treat, they result from water produced during oil and gas production, inland desalination concentrate, landfill leachate (a major problem for municipal solid waste landfills), flue gas desulfurization wastewater from fossil-fuel power plants, and effluent from industrial processes.

If hypersaline brines are improperly managed, they can pollute both surface and groundwater resources. But if there were a simple, inexpensive way to desalinate the brines, vast quantities of water would be available for all kinds of uses, from agriculture to industrial applications, and possibly even for human consumption.

A Columbia Engineering team led by Ngai Yin Yip, assistant professor of earth and environmental engineering, reports that they have developed a radically different desalination approach -- "temperature swing solvent extraction (TSSE)" -- for hypersaline brines. The study, published online in Environmental Science & Technology Letters, demonstrates that TSSE can desalinate very high-salinity brines, up to seven times the concentration of seawater. This is a good deal more than reverse osmosis, the gold-standard for seawater desalination, and can hold handle approximately twice seawater salt concentrations.

Currently, hypersaline brines are desalinated either by membrane (reverse osmosis) or water evaporation (distillation). Each approach has limitations. Reverse osmosis methods are ineffective for high-saline brines because the pressures applied in reverse osmosis scale with the amount of salt: hypersaline brines require prohibitively high pressurizations. Distillation techniques, which evaporate the brine, are very energy-intensive.

Yip has been working on solvent extraction, a separation method widely employed for chemical engineering processes. The relatively inexpensive, simple, and effective separation technique is used in a wide range of industries, including production of fine organic compounds, purification of natural products, and extraction of valuable metal complexes.

"I thought solvent extraction could be a good alternative desalination approach that is radically different from conventional methods because it is membrane-less and not based on evaporative phase-change," Yip says. "Our results show that TSSE could be a disruptive technology -- it's effective, efficient, scalable, and can be sustainably powered."

TSSE utilizes a low-polarity solvent with temperature-dependent water solubility for the selective extraction of water over salt from saline feeds. Because it is membrane-less and not based on evaporation of water, it can sidestep the technical constraints that limit the more traditional methods. Importantly, TSSE is powered by low-grade heat (< 70 C) that is inexpensive and sometimes even free. In the study, TSSE removed up to 98.4% of the salt, which is comparable to reverse osmosis, the gold standard for seawater desalination. The findings also demonstrated high water recovery >50% for the hypersaline brines, also comparable to current seawater desalination operations. But, unlike TSSE, reverse osmosis cannot handle hypersaline brines.

"We think TSSE will be transformational for the water industry," he adds. "It can displace the prevailing practice of costly distillation for desalination of high-salinity brines and tackle higher salinities that RO cannot handle," Yip adds. "This will radically improve the sustainability in the treatment of produced water, inland desalination concentrate, landfill leachate, and other hypersaline streams of emerging importance. We can eliminate the pollution problems from these brines and create cleaner, more useable water for our planet."

Yip's TSSE approach has a clear path to commercialization. The heat input can be sustainably supplied by low-grade thermal sources such as industrial waste heat, shallow-well geothermal, and low-concentration solar collectors. He is now working on further refining how TSSE works as a desalination method so that he can engineer further improvements in performance and test it with real-world samples in the field.

Two years ago, XPrize extended its list of pioneering technology competitions with a new contest aimed at the problem of global water security. After revealing the five finalists earlier in the year, the foundation has today announced the grand prize winner, which outshone almost 100 competitors with its superior ability to harvest fresh water from thin air.

The Water Abundance XPrize drew 98 competing teams from 25 countries, who were asked to develop and demonstrate technologies capable of harvesting 2,000 L (528 gal) of water from the atmosphere each day. They needed to be powered entirely by renewable energy, and produce water at a cost of no more than two cents per liter (0.26 gal).

Over the month of September, two finalists were made to fully demonstrate their devices satisfying these requirements, with LA-based Skysource/Skywater Alliance coming up trumps. Its range of deployable machines pull moisture from the air, condense it and then filter it into fresh water, with outputs ranging from 30 gal (113 L) to 300 gal (1,135 L) per day.

Skysource/Skywater Alliance claims its device harvests atmospheric water more efficiently than any other method(Credit: Skysource/Skywater Alliance)

The company's website states that it harvests atmospheric water more efficiently than any other method, and we guess it now has the accolades to back up its claims, along with US$1.5 million in prize money.

Coming in second place was Hawaii's JMCC WING, whose solution combines a high torque wind energy system with an atmospheric water harvester as a way of keeping energy requirements, and thereby costs per liter, to a minimum. JMCC WING has received $150,000 for its efforts.

JMCC WING's solution combines a high torque wind energy system with an atmospheric water harvester(Credit: JMCC WING)

Tuesday, October 16, 2018

Date: October 9, 2018Source: New Jersey Institute of TechnologySummary: Researchers have detailed the discovery of the first bacterium known capable of simultaneously degrading the pair of chemical contaminants -- 1,4-Dioxane and 1,1-DCE.

Image of DD4 cells.Credit: NJIT, Mengyan Li

Known as a chemical manufacturing by-product of many cosmetics and home cleaning products, the industrial solvent 1,4-Dioxane is now considered by the Environmental Protection Agency to be an "emerging contaminant" and "likely human carcinogen" that can be found at thousands of groundwater sites nationally -- potentially representing a multi-billion dollar environmental remediation challenge.

However, it is the contaminant's frequent co-existence with another toxic chemical -- 1,1-Dichloroethylene (1,1-DCE) -- that has been found to aid in 1,4-dioxane's resistance to certain remediation strategies, including degradation by naturally-occurring microbes.

Now, New Jersey Institute of Technology (NJIT) researchers have detailed the discovery of the first bacterium known capable of simultaneously degrading the pair of chemical contaminants -- 1,4-Dioxane and 1,1-DCE. The study, published in Environmental Science & Technology Letters, also showcases the efficiency of the microbe, called Azoarcus sp. DD4 (DD4), in reducing 1,4-dioxane and 1,1-DCE levels in co-contaminated groundwater samples.

"Nationwide, researchers have found that more than 80% of the groundwater sites contaminated with 1,4-dioxane also contain 1,1-DCE," said Mengyan Li, assistant professor of chemistry and environmental science at NJIT. "This pair of chemicals are toxic and costly to remove from the environment because the pair have very different properties that typically require separate treatment solutions. Biodegradation by DD4 is the first biological method we have found for treating both compounds concurrently, and it is also environmentally-friendly and cost-efficient."

Li's research team initially discovered the DD4 microbe from activated sludge samples collected from a municipal wastewater treatment facility. In the lab, Li's team was able to isolate and analyze DD4's ability to degrade 1,4-dioxane and 1,1-DCE simultaneously in contaminated groundwater samples over a two-week period.

Applying the microbe to the field samples, Li's team observed that concentration of 1,4-dioxane was degraded from 10 parts-per-million (10 ppm) -- or 3,000 times the limit of the EPA's guidance level of 0.35 parts-per-billion (0.35 ppb) -- to under 0.38 ppb. The lab also found 1,1-DCE concentration levels reduced from over 3 ppm to below 0.02 ppm.

Notably, DD4 displayed resistance to cellular toxicity produced by the metabolites of 1,1-DCE, which typically inhibit the ability of other bacteria capable of degrading 1,4-dioxane. Li's team observed that although DD4 was partially inhibited in its ability to degrade 1,4-dioxane when excessive amounts of 1,1-DCE were artificially spiked in the water samples, 1,4-dioxane degradation capability immediately recovered once the microbe had depleted 1,1-DCE.

"Overall, we were impressed by the performance of DD4," said Li. "We did not add nutrients like ammonia for the microbe to feed on, or other facilitators that might enhance the bacterium's activity. This demonstrated to us the potential of this bacterium for future use in the field."

In an analysis of the genetic makeup of DD4, Li's lab identified a potentially key gene related to the microbe's chemical degradation activity. Li says that the gene encodes for an enzyme, called soluble di-iron monooxygenase (SDIMO), with versatile capabilities of breaking down chemical pollutants. "We want to characterize it (this enzyme) further to see if we can better learn the mechanism underlying how DD4 degrades these contaminants." said Li.

Along with DD4's 1,1-DCE-resistance and ability to degrade the co-contaminants concurrently, Li says the bacterium possesses several other key traits that make it conducive as a potential bioremediation solution at contaminated groundwater sites -- such as its ability to disperse freely through water to remediate larger areas of contamination, rather than aggregating like other bacterial treatments. The microbe can also be cultured rapidly and can sustain for extended periods with limited nutrient source.

"We tested the bacterium in normal refrigerated temperature over three days and its viability remained above 80%," said Li. "After a week, half were still alive. This makes it even more desirable because it would be able to survive the delivery time from the lab to contaminated sites."

Li's lab is now conducting further tests of the bacterium in the lab to better understand how DD4 might perform at contaminated water sites. With feasibility tests already underway, Li says his team could begin field demonstrations of DD4 as a water treatment solution for 1,4-dioxane and 1,1-DCE contamination sites as early as next year.

"Ideally, we may inject the bacteria into the center of a contamination zone, or try growing them on the surface of bio-barriers that help stop spread of contamination," said Li. "First, we'd like to do more tests and possibly develop a gene marker that helps us assess the bacteria's performance. Then, we would like to move into the field."

Monday, August 13, 2018

Date: August 3, 2018Source: Virginia TechSummary: New research aims to cut down on waste -- and consumer frustration -- with a novel approach to creating super slippery industrial packaging. The study establishes a method for wicking chemically compatible vegetable oils into the surfaces of common extruded plastics, like those used for ketchup packets and other condiments.

Virginia Tech doctoral student Ranit Mukherjee observes a dollop of ketchup as it moves on a super slippery plastic film. Mukherjee is the lead author on a study that yielded a novel approach to creating super slippery industrial packaging.Credit: Virginia Tech

Almost everyone who eats fast food is familiar with the frustration of trying to squeeze every last drop of ketchup out of the small packets that accompany french fries.

What most consumers don't realize, however, is that food left behind in plastic packaging is not simply a nuisance. It also contributes to the millions of pounds of perfectly edible food that Americans throw out every year. These small, incremental amounts of sticky foods like condiments, dairy products, beverages, and some meat products that remain trapped in their packaging can add up to big numbers over time, even for a single household.

New research from Virginia Tech aims to cut down on that waste -- and consumer frustration -- with a novel approach to creating super slippery industrial packaging.

The study, which was published in Scientific Reports and has yielded a provisional patent, establishes a method for wicking chemically compatible vegetable oils into the surfaces of common extruded plastics.

Not only will the technique help sticky foods release from their packaging much more easily, but for the first time, it can also be applied to inexpensive and readily available plastics such as polyethylene and polypropylene.

These hydrocarbon-based polymers make up 55 percent of the total demand for plastics in the world today, meaning potential applications for the research stretch far beyond just ketchup packets. They're also among the easiest plastics to recycle.

"Previous SLIPS, or slippery liquid-infused porous surfaces, have been made using silicon- or fluorine-based polymers, which are very expensive," said Ranit Mukherjee, a doctoral student in the Department of Biomedical Engineering and Mechanics within the College of Engineering and the study's lead author. "But we can make our SLIPS out of these hydrocarbon-based polymers, which are widely applicable to everyday packaged products."

First created by Harvard University researchers in 2011, SLIPS are porous surfaces or absorbent polymers that can hold a chemically compatible oil within their surfaces via the process of wicking. These surfaces are not only very slippery, but they're also self-cleaning, self-healing, and more durable than traditional superhydrophobic surfaces.

In order for SLIPS to hold these oils, the surfaces must have some sort of nano- or micro-roughness, which keeps the oil in place by way of surface tension. This roughness can be achieved two ways: the surface material is roughened with a type of applied coating, or the surface material consists of an absorbent polymer. In the latter case, the molecular structure of the material itself exhibits the necessary nano-roughness.

Both techniques have recently gained traction with startups and in limited commercial applications. But current SLIPS that use silicone- and fluorine-based absorbent polymers aren't attractive for industrial applications due to their high cost, while the method of adding roughness to surfaces can likewise be an expensive and complicated process.

"We had two big breakthroughs," said Jonathan Boreyko, an assistant professor of biomedical engineering and mechanics and a study co-author. "Not only are we using these hydrocarbon-based polymers that are cheap and in high demand, but we don't have to add any surface roughness, either. We actually found oils that are naturally compatible with the plastics, so these oils are wicking into the plastic itself, not into a roughness we have to apply."

In addition to minimizing food waste, Boreyko cited other benefits to the improved design, including consumer safety and comfort.

"We're not adding any mystery nanoparticles to the surfaces of these plastics that could make people uncomfortable," he said. "We use natural oils like cottonseed oil, so there are no health concerns whatsoever. There's no fancy recipe required."

While the method has obvious implications for industrial food and product packaging, it could also find widespread use in the pharmaceutical industry. The oil-infused plastic surfaces are naturally anti-fouling, meaning they resist bacterial adhesion and growth.

Although the technique may sound very high-tech, it actually finds its roots in the pitcher plant, a carnivorous plant that entices insects to the edge of a deep cavity filled with nectar and digestive enzymes. The leaves that form the plant's eponymous shape have a slippery ring, created by a secreted liquid, around the periphery of the cavity. When the insects move onto this slippery ring, they slide into the belly of the plants.

The pitcher plant's innovation -- which engineers are now copying with great success -- is the combination of a lubricant with some type of surface roughness that can lock that lubricant into place very stably with surface tension.

"We're taking that same concept, but the roughness we're using is just a common attribute of everyday plastics, which means maximal practicality," said Boreyko.

This research was funded through an industrial collaboration with Bemis North America. Additional co-authors of the study include Mohammad Habibi, a Virginia Tech mechanical engineering graduate student; Ziad Rashed, an engineering science and mechanics 2018 graduate from Virginia Tech's undergraduate program; and Otacilio Berbert and Xiangke Shi, both of Bemis North America.

Friday, August 3, 2018

Date: July 31, 2018Source: Penn StateSummary: Drinking water from wells in rural north central Pennsylvania had low levels of pharmaceuticals, according to a new study.

While septic tanks are generally installed downgradient of wells, contaminant from septic systems can impact well water quality, especially if the septic systems are not maintained or were improperly installed. Pharmaceuticals that are incompletely degraded in septic tanks and leaching fields can travel with wastewater and infiltrate groundwater.Credit: Heather Gall Research Group / Penn State

Drinking water from wells in rural north central Pennsylvania had low levels of pharmaceuticals, according to a study led by Penn State researchers.

Partnering with volunteers in the University's Pennsylvania Master Well Owner Network, researchers tested water samples from 26 households with private wells in nine counties in the basin of the West Branch of the Susquehanna River. All samples were analyzed for seven over-the-counter and prescription pharmaceuticals: acetaminophen, ampicillin, caffeine, naproxen, ofloxacin, sulfamethoxazole and trimethoprim.

At least one compound was detected at all sites. Ofloxacin and sulfamethoxazole -- antibiotics prescribed for the treatment of a number of bacterial infections -- were the most frequently detected compounds. Caffeine was detected in approximately half of the samples, while naproxen -- an anti-inflammatory drug used for the management of pain, fever and inflammation -- was not detected in any samples.

"It is now widely known that over-the-counter and prescription medications are routinely present at detectable levels in surface and groundwater bodies," said Heather Gall, assistant professor of agricultural and biological engineering, whose research group in the Penn State's College of Agricultural Sciences conducted the study. "The presence of these emerging contaminants has raised both environmental and public health concerns, particularly when these water supplies are used as drinking water sources."

The good news, Gall pointed out, is that the concentrations of the pharmaceuticals in groundwater sampled were extremely low -- at parts per billion levels. However, given that sampling with the Master Well Owner Network only occurred once, the frequency of occurrence, range of concentrations and potential health risks are not yet well understood, especially for these private groundwater supplies.

The researchers used a simple modeling approach based on the pharmaceuticals' physicochemical parameters -- degradation rates and sorption factors -- to provide insight into the differences in frequency of detection for the target pharmaceuticals, noted lead researcher Faith Kibuye, who will graduate with a doctoral degree in biorenewable systems next year.

She explained that calculations revealed that none of the concentrations observed in the groundwater wells posed any significant human health risk, with risk quotients that are well below the minimal value. However, the risk assessment does not address the potential effect of exposure to mixtures of pharmaceuticals that are likely present in water simultaneously, she said. For example, as many as six of the analyzed pharmaceuticals were detected in some groundwater samples.

"There remains a major concern that even at low concentrations, pharmaceuticals could interact together and influence the biochemical functioning of the human body, so even at very low concentrations they might have some kind of synergistic effect," Kibuye said. "We only analyzed for seven pharmaceuticals but the chances are that there may have been many more."

The findings of the research -- which Kibuye will present today (July 31) at the annual meeting of the American Association of Agricultural and Biological Engineers in Detroit -- should be of interest the world over because groundwater is a critical supply of drinking water globally.

It is estimated that half of the population accesses potable water from groundwater aquifers. In the United States, approximately 13 million households use private wells as their drinking water source, according to the U.S. Environmental Protection Agency. In Pennsylvania, approximately one-third of the residents receive their drinking water from private groundwater wells, Penn State Extension surveys show.

It is common for homeowners with private wells to also have septic tanks on their properties for treatment of their wastewater. And while septic tanks are generally installed downgradient of the well, it is possible that contaminant from septic systems can impact well-water quality, especially if the septic systems are not maintained or were improperly installed.

"While common contaminant issues include fecal coliform, E. coli and nitrate, pharmaceuticals and other compounds of emerging concern pose potential threats to well water quality," Kibuye said. "Pharmaceuticals that are incompletely degraded in septic tanks and leaching fields can therefore travel with wastewater plumes and impact groundwater, potentially making septic systems important point sources to surrounding domestic groundwater sources."

Friday, July 20, 2018

Three years ago, the drought-stricken city of Los Angeles covered the surface of the LA Basin with 96 million shade-providing floating balls, in order to keep the water beneath from evaporating. Now, an international study suggests that the making of the plastic balls may have have used up more water than they saved.

The "shade balls" were left in place on the reservoir for approximately one and a half years, during the latter part of the 2011 - 2017 California drought. According to the study, they kept an estimated 1.7 million cubic meters (60 million cubic feet) of water from evaporating. Unfortunately, however, it is also estimated that production of the balls used up 2.9 million cubic meters of water (102 million cubic feet). This happened at locations where the oil and natural gas used to produce the plastic were refined, and where the electricity necessary for production was generated.

In order for the shade balls to save as much water as was used in manufacturing them, they would reportedly have to be left on the reservoir for at least two and a half years – and that's only if drought conditions persisted for the entire period.

Additionally, the study points out that the manufacturing process would have had other negative environmental costs, such as the generation of carbon emissions and water pollution.

"We are very good at quick technological fixes, but we often overlook the long-term and secondary impacts of our solutions," says study co-author Dr. Kaveh Madani, from Imperial College London. "This is how the engineering community has been solving problems; solving one problem somewhere and creating a new problem elsewhere … We are not suggesting that shade balls are bad and must not be used. We are just highlighting the fact that the environmental cost of shade balls must be considered together with their benefits."

The findings of the study, which also included scientists from MIT in the US and the University of Twente in the Netherlands, were recently published in the journal Nature Sustainability.

Friday, July 13, 2018

Date: July 12, 2018Source: Washington State UniversitySummary: Researchers have created a sustainable alternative to traditional concrete using coal fly ash, a waste product of coal-based electricity generation.

Chemical engineering student Ka Fung Wong looks at the data log, which is used to gather data from sensors buried under the concrete test plot.Credit: WSU

Washington State University researchers have created a sustainable alternative to traditional concrete using coal fly ash, a waste product of coal-based electricity generation.

The advance tackles two major environmental problems at once by making use of coal production waste and by significantly reducing the environmental impact of concrete production.

Xianming Shi, associate professor in WSU's Department of Civil and Environmental Engineering, and graduate student Gang Xu, have developed a strong, durable concrete that uses fly ash as a binder and eliminates the use of environmentally intensive cement. They report on their work in the August issue of the journal, Fuel.

Reduces Energy Demand, Greenhouse Emissions

Production of traditional concrete, which is made by combining cement with sand and gravel, contributes between five and eight percent of greenhouse gas emissions worldwide. That's because cement, the key ingredient in concrete, requires high temperatures and a tremendous amount of energy to produce.

Fly ash, the material that remains after coal dust is burned, meanwhile has become a significant waste management issue in the United States. More than 50 percent of fly ash ends up in landfills, where it can easily leach into the nearby environment.

While some researchers have used fly ash in concrete, they haven't been able to eliminate the intense heating methods that are traditionally needed to make a strong material.

"Our production method does not require heating or the use of any cement," said Xu.

Molecular Engineering

This work is also significant because the researchers are using nano-sized materials to engineer concrete at the molecular level.

"To sustainably advance the construction industry, we need to utilize the 'bottom-up' capability of nanomaterials," said Shi.

The team used graphene oxide, a recently discovered nanomaterial, to manipulate the reaction of fly ash with water and turn the activated fly ash into a strong cement-like material. The graphene oxide rearranges atoms and molecules in a solution of fly ash and chemical activators like sodium silicate and calcium oxide. The process creates a calcium-aluminate-silicate-hydrate molecule chain with strongly bonded atoms that form an inorganic polymer network more durable than (hydrated) cement.

Aids Groundwater, Mitigates Flooding

The team designed the fly ash concrete to be pervious, which means water can pass through it to replenish groundwater and to mitigate flooding potential.

Researchers have demonstrated the strength and behavior of the material in test plots on the WSU campus under a variety of load and temperature conditions. They are still conducting infiltration tests and gathering data using sensors buried under the concrete. They eventually hope to commercialize the patented technology.

"After further testing, we would like to build some structures with this concrete to serve as a proof of concept," said Xu.

The research was funded by the U.S. Department of Transportation's University Transportation Centers and the WSU Office of Commercialization.

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The American Academy of Environmental Engineering and Scientists is a not-for-profit 501(c)(6) organization serving the Environmental Engineering and Environmental Science professions by providing Board Certification to those who qualify through experience and testing. The Academy also provides training through workshops and seminars, participates in accrediting universities, publishes a periodical and other reference material, interacts with students and young professionals, sponsors a university lecture series, and rewards outstanding achievements through its international awards program.