The new reverse osmosis (RO) membranes offer a huge improvement over current ones, which clog easily when bacteria and other particles build up on the surface, say scientists with the UCLA Henry Samueli School of Engineering and Applied Science, where the new material was developed. Its this fouling that leads to higher costs as a result of greater energy demands on the pumping system, cleanup and replacement of the membranes.

This latest development comes at a time when the world is running out of freshwater. About 20% of the worlds population lacks access to safe drinking water, according to the United Nations. Climate change, overconsumption and water pollution are draining away this precious resource.

We as a nation thought we had enough water, so a decision was made in the 1970s to stop funding desalination research, said Eric Hoek, the civil and environmental engineering assistant professor who, with his team, developed the new membrane. Now, 30 years later, there is renewed interest because we realize that not only are we running out of freshwater, but the current technology is limited, we lack implementation experience and we are running out of time.

RO desalinization is currently the state-of-the-art technology for turning seawater and brackish water into fresh drinking water. The first viable RO membrane was developed and patented by UCLA engineering researchers in the 60s. But the process is still too costly and problem-plagued to be practical.

The process uses extremely high pressure to force saline or polluted water through the pores of a semi-permeable membrane. Under pressure, water molecules pass through the pores, but salt ions and other impurities cant. Over time, they clog the membranes.

Hoeks new membrane contains specially synthesized nanoparticles that are dispersed throughout a polymer film. They are designed to attract water ions, but repel the clog-producing salts and impurities. Initial tests suggest the new membranes consume 50% less energy, reducing the cost of desalinated water by as much as 25%.

Hoek is currently working with an early-stage limited partnership, NanoH2O, to develop his patent-pending technology into a membrane that could become commercially available within a year or two.

It is essential that we reduce the overall cost of desalination including energy demand and environmental issues before a major drought occurs and we lack the ability to efficiently and effectively increase our water supply, Hoek said.

Anne Burke contributed to this story.

Published: Tuesday, November 07, 2006

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