Micro-desalination device unveiled by scientists

CAMBRIDGE, MA, March 25, 2010 -- Researchers reveal small desalination device the size of a postage stamp which they claim will work without the need for membranes...

CAMBRIDGE, MA, March 25, 2010 -- Scientists have developed a small desalination device the size of a postage stamp which they claim can produce water with 99% purity.

Each device would only process small amounts of water, but researchers believe that a large number of them - 1600 units - could produce around 15 litres of water per hour.

Developed by Massachusetts Institute of Technology (MIT) and associates in Korea, a single unit was tested using water collected from Massachusetts beach. Water was deliberately contaminated with small plastic particles, protein and human blood and MIT said the unit removed more than 99% of the salt and other contaminants.

The system works by separating salts and microbes from water by electrostatically repelling them away from the ion-selective membrane in the system— so the flowing water never needs to pass through a membrane. According to researchers, this should help eliminate the need for high pressures and the problems of fouling.

The process has been called "ion concentration polarization" and was described in a paper by Postdoctoral Associate Sung Jae Kim and Associate Professor Jongyoon Han, both in MIT’s Department of Electrical Engineering and Computer Science, and colleagues in Korea.

MIT said: "While the amount of electricity required by this method is actually slightly more than for present large-scale methods such as reverse osmosis, there is no other method that can produce small-scale desalination with anywhere near this level of efficiency...If properly engineered, the proposed system would only use about as much power as a conventional light bulb."

Scientists plan to develop the product on a commercial scale over the next two years, producing a 100-unit device followed by a 10,000-unit system.

It is hoped the portable desalination units will be suitable for delivering drinking water to families or small villages in emergency situations, such as Haiti's earthquake aftermath.


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