Water. desalination + reuse

November/December 2012

Water. Desalination + reuse

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RESEARCH RESEARCH cooking with water which is killing them. Addressing a significant amount of the needed water using Suns River���s 99+% solar energy technology will not only meet the water demand more cheaply, but also avoids a major investment in electrical energy capacity. Photo: The two-effect Suns River set-up. yield comes to more than 15 L/m2 /d. With a small, low-pressure water pump as its most complex component, the Suns River still easily produces water at rates competitive with reverse osmosis (RO), the current lead technology. OpERAtiOn And mAintEnAnCE The simplicity of the solar still operation does not require a cadre of specially trained technicians and costs for operations and maintenance are a fraction of those of RO. The test unit was sized to meet or exceed the cooking and drinking water needs of a family of four. The solar still is completely scalable so that units of 10 or 100 times that capacity are completely within the scope. Even larger commercial, industrial and municipal units are dependent only on the amount of space available. The current trend of meeting the growth in water demand with RO would require a large increase in electrical energy supply. One estimate indicates that more than two dozen nuclear power plants might be needed to address growth in water needs in the next decade using RO. In addition there are more than one billion people who are today drinking and USE fOR diStRibUtEd pEOplE The scalability of the Suns River still means that distributed populations like those in the western US, Africa and the Australian outback can produce good water where they consume it, saving current huge transportation and logistics costs. Suns River plans to have market-ready units for home use available soon. On the topic of major water facilities, Suns River believes that any major water project located within 40�� north and 40�� south latitudes should have at least some solar capacity in the design. In addition to producing pure distilled water at competitive costs, Suns River has the potential to process RO brine to harvest additional water and reduce brine disposal requirements. The purity of the Suns River product blended with RO product can also help meet the stringent barium limits. The Suns River solar distillation process can have a significant impact on the desalination industry and alter the water production and distribution systems in the areas most in need of water today. The company is now seeking investors to help speed the launch of this critically needed technology.l MIT engineers tiny graphene membrane Researchers at the Massachusetts Institute of Technology (MIT) have published new research on the engineering of a very thin graphene membrane that could be used for tasks such as desalination without tearing. The work appears in a paper, Selective Molecular Transport through Intrinsic Defects in a Single Layer of CVD Graphene, http://pubs.acs.org/doi/abs/10.1021/ nn303869m published in the American Chemical Society���s journal ACS Nano on 2 October 2012. Professor Rohit Karnik and a team from MIT, Oak Ridge National Laboratory, Indian Institute of Technology and King Fahd University of Petroleum & Minerals, Saudi Arabia, made a membrane by transferring a single layer of CVD graphene on a porous polycarbonate substrate. The group settled on graphene, in part because of its extremely thin structure and its strength: a sheet of graphene is as thin as a single atom, but strong enough to pass high volumes of fluids without falling apart. The team set out to engineer a membrane spanning 25 mm2 ��� a surface area that is large by graphene standards, holding about a quadrillion carbon atoms. They used graphene synthesized by chemical vapor deposition, borrowing expertise from another MIT research group. Experiments showed that the membrane was not impermeable and that salts flowed through it. There was also a limit to the size of molecules that would pass through the membrane. As a final experiment, Karnik and Sean O���Hern, also from MIT���s Mechanical Engineering Department, observed the actual holes in the graphene membrane, looking at the material through a highpowered electron microscope at Oak Ridge | 40 | Desalination & Water Reuse | November-December 2012 in collaboration with Juan-Carlos Idrobo. They found that pores ranged in size from about 1 to 12 nm ��� just wide enough to selectively let some small molecules through. ���No one has looked for holes in graphene before,��� says Karnik, associate professor of mechanical engineering at MIT. ���There���s a lot of chemical methods that can be used to modify these pores, so it���s a platform technology for a new class of membranes.��� When asked by D&WR how this research tied in with the MIT paper on graphene membranes reported in June 2012 http://www.desalination.biz/news/ news_story.asp?id=6605, Karnik replied that the previous study was a simulation showing the potential of graphene for highperformance desalination, while his study was experimental. Experimentally, more progress was needed before desalination could be achieved, and this was a first step. Project seeks to generate electricity and ammonia from urine Work began in September 2012 at Wetsus, the Dutch centre of excellence for sustainable water technology, on a project funded by the European Union to generate electricity and recover ammonia from urine. Project FP7 ValueFromUrine will develop, optimize and evaluate an innovative bio-electrochemical system that allows for the recovery of phosphorus, ammonia and electricity from urine. Phosphorus is a limited resource and ammonia production from inert nitrogen gas in the atmosphere is an energyintensive process. The main use of phosphorus and ammonia is fertilizer production. The recovery of nutrients from urine can help to overcome future shortages. Using an innovative bio-electrochemical system (Microbial Fuel Cell) in combination with phosphorus recovery precipitation (Struvite), valuable ammonia and phosphate salt can be recovered and energy produced. During the inaugural meeting, the seven project partners laid the foundations for the project. They are: Wetsus, DeSaH BV (Netherlands), Magneto Special Anodes (Netherlands), Mast Carbon (UK), Abengoa Water (Spain), CRP Henri Tudor (Luxemburg), University of Minho (Portugal). Veolia wastewater treatment lowers PPCPs and phosphorus Veolia Water North America chose the Water Environment Federation���s annual WEFTEC conference in Chicago to release a study on 3 October 2012 showing successful removal of pharmaceuticals and phosphorus from wastewater using its Acti���o�� Carb technology. The presence of pharmaceuticals and personal-care products (PPCPs) is of particular concern to utilities reusing wastewater, and California, for instance, is currently considering legislation requiring monitoring for constituents of emerging concern (CECs), which include PPCPs. So far, there are few data on any health and environmental threats. To date, no one process has been found to be successful in removing all these contaminants, though they can be considerably reduced with a combination of technologies, usually involving reverse osmosis, which a recent WateReuse Research Foundation project found removed 95% of CECs. As part of a multi-year partnership with a team of scientists from the University of Wisconsin-Milwaukee, the Acti���o�� Carb study was conducted by process engineers from Veolia Water and its subsidiary Kruger Inc., with the support of the Milwaukee Metropolitan Sewerage District and the Water Environment Research Foundation. With the use of Acti���o�� Carb, 75% of the selected PPCPs were removed from the wastewater. Additionally, phosphorus was reduced to a concentration of 0.05 mg/L or less, well below the US Environment Protection Agency���s regulatory limit of 1.0 mg/L. Nanomaterials for safer water use Nanomaterials offer opportunities to develop next generation applications for drinking water disinfection and safer water reuse ��� this is the message that Dr Pedro Alvarez of Rice University presented in the 2012 Clarke Lecture in California on 2 November 2012. In his lecture Convergence of Nanotechnology and Microbiology: Emerging Opportunities for Water Disinfection, Microbial Control, and Integrated Urban Water Management, Alvarez described how nanotechnology offers safer and more sustainable options for water treatment; which nanotechnologies have antimicrobial properties; nanotechnology-enabled disinfection; and possible implementation barriers. The lecture highlighted how the sizedependent properties of some nanomaterials offer opportunities to develop nextgeneration applications for drinking water disinfection and safer water reuse. Processes enabled by nanotechnology are modular, multifunctional, and high-ef���ciency, and can be broadly applicable in both industrialized and developing countries. 2013 reuse research conference call The WateReuse Research Foundations has issued a call for papers for its 17th Annual Water Reuse & Desalination Research Conference on 6-7 May 2013 in Phoenix, Arizona. Abstracts need to be submitted to the foundation���s website by 3 December 2012. The Foundation���s Research Conference provides an opportunity for the water reuse and desalination communities to hear and see presentations by researchers on the latest results of ongoing research. Can polymer replace titanium in thermal desalination? Researchers from the Fraunhofer Institute for Manufacturing Technology & Advanced Materials in Bremen, Germany, have developed a heat-conducting polymer composite tube which they believe will soon be replacing titanium in thermal desalination plants. The material was introduced at the Composites trade fair in October. ���We introduced metal particles into the material - or more precisely, we add up to 50% copper micro���bers by volume. This does not change the processing properties of the composite, and it can still be processed as any other polymer would,��� notes Arne Haberkorn, a scientist at IFAM. The researchers have already developed the material itself; now they want to optimize its thermal conductivity. To accomplish this, they are installing the piping in a pilot seawater-desalination plant to test its thermal conductivity and check to see how much of a microorganismbased coating forms on the pipes and how heavily the material corrodes in its salty surroundings. They will then optimize the composite properties based on the results. The researchers have set the evaporation process to run at a temperature of 70��C ��� so there is hot gas heated to 70��C pumped through the pipelines. This offers several advantages: fewer deposits congregate on the pipes, the material does not corrode as quickly, and the pressure differential between the inside and outside of the piping is not as dramatic. November-Decemberr 2012 | Desalination & Water Reuse | 41 |

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