Water. Desalination + reuse
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RESEARCH | 28 | Desalination & Water Reuse | February-March 2016 Well being: a bug in produced water could clean up. Research findings by the US Geological Survey (USGS) have indicated that bacteria in produced water could improve the way that fluid from shale gas operations is handled and reused. The study found that bacteria could be useful in breaking down contaminants in produced water. The findings could have "important implications" for energy companies, according to the USGS report. "Microbial activity detected in these samples could turn out to be an advantage by contributing to the degradation of organic compounds present in the produced waters. Potentially, microbes could also serve to help mitigate the effects of organic contaminants during the disposal or accidental release of produced waters," it said. The USGS studied 13 hydraulically fractured shale gas wells in north-central Pennsylvania. Large differences in the organic geochemistry including petroleum products and microbiology such as bacteria populations of the produced waters were "striking findings of the study," USGS reported. USGS microbiologist, and lead author of the study, Denise Akob, said: "Some wells appeared to be hotspots for microbial activity. But this was not predicted by well location, depth, or salinity. The presence of microbes seemed to be associated with concentrations of specific organic compounds — for example, benzene or acetate — and the length of time that the well was in production." The researchers speculated that increased microbial activity in water with high levels of organic compounds could prove useful in future efforts to clean up fracking accidents. RESEARCHERS find dAtA CEntRE dESAlinAtion CombinAtion will REduCE EmiSSionS Studies by a company proposing to construct a groundbreaking combination of desalination plant and data centre have shown the facility will cause only limited negative impact to the environment according to the researchers. The three-year study by DeepWater Desal found that the 125 Ml/d desalination plant proposed for a site on the central California coast would: • reduce greenhouse emissions by using coolant water from a proposed data centre; • kill few fish; • meet current and future restrictions on release of brine into the ocean; and • create fewer geological risks than drilling owing to its use of a deepwater canyon as its seawater source. "What's exciting for us is that our theories have been validated by these studies," said DeepWater spokesman David Armanasco. The plant has been proposed as a future water source for supplier Soquel Creek Water District. The proposal calls for drawing cold seawater from the Monterey Submarine Canyon. After using that water to cool a proposed data centre on the site the then warmed water will pass to a reverse-osmosis desalination plant. The heat absorbed in the data centre cooling will reduce the energy needed for desalination. This combination of data centre cooling and desalination is unique and would emit significantly less carbon than would both facilities operating separately. uS wAtER RECyCling RESEARCH bodiES to mERgE US research bodies, Water Environment Research Foundation (WERF) and the WateReuse Research Foundation (WRRF), have unveiled plans to merge both organisations. Chairman of the WRRF, Doug Owen, said the merger would create "the opportunity to strengthen the value of water that was historically used only once." Owen's counterpart at WERF, Kevin Shafer, added: "Our organizations share a common commitment to making the most of the water we use. Merging will strengthen that commitment as well as increase the return on investment in research for our members and the industry as a whole." According to their joint release, the nonprofit organizations' research areas are complementary in that WateReuse advocates policies, laws and funding at the state and federal level to increase the practice of recycling and desalinating water while WERF focuses on scientific research into wastewater and stormwater issues. They predict that the proposed merger will "create synergies, reduce future water research redundancy, further the evolution toward a unified voice for water, and increase the value proposition to their respective subscribers by enhancing and leveraging investments." Owen, said: "The water industry is currently at a critical juncture as it relates to acceptance and implementation of reuse." illinoiS RESEARCHERS idEntify ultRA EffiCiEnt mEmbRAnE mAtERiAl University of Illinois engineers have claimed to have identified a nanoporous material that could be deployed in desalination with greater efficiency promise than graphene. Using supercomputing, the Illinois team modelled various thin- film membranes and found that molybdenum disulphide showed the greatest efficiency, filtering through up to 70% more water than graphene membranes. "Finding materials for efficient desalination has been a big issue, and I think this work lays the foundation for next-generation materials. These materials are efficient in terms of energy usage and fouling, which are issues that have plagued desalination technology for a long time," said study leader Narayana Aluru, professor of mechanical science and engineering at the University of Illinois. The research was published in Nature Communications. "Reverse osmosis is a very expensive process," Aluru said. "And it's not very efficient. In addition, the membranes fail because of clogging. So we'd like to make it cheaper and make the membranes more efficient so they don't fail as often. We also don't want to have to use a lot of pressure to get a high flow rate of water." The thinnest membranes are likely to be the most efficient because the force needed to push water through is proportional to membrane thickness. The Illinois researchers have looked at nanometre-thin membranes including graphene. Molybdenum disulphide is, according to the researchers, a robust material, so even a thin sheet is able to withstand the pressures in desalination. The Illinois researchers are establishing collaborations to test molybdenum disulphide in desalination and to test its rate of fouling. miCRobES Could impRovE pRoduCEd wAtER REuSE