Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/640467
February-March 2016 | Desalination & Water Reuse | 27 | Singapore researchers claim to have produced a biomimetic membrane with the potential to reduce water purification costs by up to 30%. National University of Singapore Environmental Research Institute (NERI) scientists have designed and made a new water purification and treatment system that incorporates aquaporins –cell membrane proteins that conduct high volumes of water in and out of cells at very low pressures while blocking ions and other solutes. The NERI team – led by Professor Tong Yen Wah – has succeeded in placing aquaporin proteins onto polymer membranes to act as channels that allow only water to go through very quickly while consuming little energy. "The biomimetic membrane is constructed to mimic the layers of cells on the roots of mangrove trees by embedding nano-sized aquaporin-vesicles onto a stable and functional ultrafiltration substrate membrane using an innovative yet simple and easy-to-implement surface imprinting technology," Tong explained. Aquaporins in mangrove plants which survive in salt water, filter 90-95% of the salt at their roots. In another example of aquaporin performance, the human kidney is able to purify up to 150 litres of water daily. Unlike conventional biomimetic membranes which tend to be quite fragile, the novel membrane has high mechanical strength and stability making it suitable for industrial applications in water treatment and desalination the NERI team has claimed. The team said it was in discussions with a US-based company to develop a pilot-scale module to test the feasibility of the membranes. MIT researchers unveIl groundbreakIng desalInaTIon sysTeM A research team at Massachusetts Institute of Technology (MIT) has developed a desalination system that uses a strong electric field acting on a stream of flowing water. The field pushes ions in the salty water to one side of the flow and fresh water to the other so the two streams can readily be separated. This approach – called shock electrodialysis – is "a fundamentally new and different separation system," according to the leader of the research, professor of chemical engineering and mathematics, Martin Bazant. It carries out a "membraneless separation" of ions and particles from water. Swamp thing: membrane developers look to the mangrove for direction in taking the pressure out of desalting. In Bazant's process, water flows through a porous column of glass particles sandwiched between electrodes that create "a very strong gradient," according to Bazant. When current flows through the electrodes, the salt solution in the glass column divides into a high salt concentration flow and a low concentration flow. When the electric current is increased it reaches a point where it creates a shock that splits the fresh and saline stream so they can be separated by a barrier placed at the dividing line between he two flows. Bazant explained that the system does not drive water through a membrane to effect separation so it is not susceptible to fouling as in reveres osmosis or even conventional electrodialysis. The new system is a continuous process, based on water flowing through an inexpensive porous medium that the MIT team claim should be easy to scale up for desalination. The system not only removes salt, but also other contaminants – and because of the electrical current passing through, it may also sterilize the stream said research team member, graduate student Sven Schlumpberger. "The electric fields are pretty high, so we may be able to kill the bacteria," he said. The research produced a laboratory demonstration of the process. Bazant said the next step was to scale that up and carry out practical testing. Initially shock electrodialysis would not compete with reverse osmosis for large-scale seawater desalination, but it could in applications treating produced water such as water effluent from fracking, Schlumpberger said. He went on to say the system needs little by the way of infrastructure, so it might form the basis of portable systems for use in remote locations. Masdar sTeps up TIes wITh chIna Abu Dhabi's Masdar Institute of Science and Technology is stepping up its research collaborations, knowledge exchange and industrial partnerships, with China. Abu Dhabi has recently signed agreements with Beijing on finance, investment, logistics, energy, education and technology. A research agreement between Masdar Institute and a leading Chinese university was included. The agreement is expected to boost Masdar Institute's engagement with China. The Masdar Institute has a number of Chinese students and postdoctoral researchers "who enrich the institute with their talent, expertise and dedication while leveraging the research infrastructure and support provided at Masdar Institute to develop solutions of relevance to the needs of both China and the UAE," said the institute. Professor of Chemical and Environmental Engineering at Masdar Institute, Dr Linda Zou – a Chinese national – is spearheading a number of critical research projects. She is the principal investigator in collaboration between Masdar and engineering giant, Veolia, in capacitive deionisation (CapDI). The study is evaluating potential enhancements in this emerging low-energy desalination technology. Zou's collaboration is focused on getting CapDI to market. planT cell MeMbrane MIMIc shrInks desalInaTIon cosTs RESEARCH