Water Warriors

The California Aqueduct brings water to arid Southern California from the Sacramento River Delta.

Copyright © Mark Hanauer

More problematic still is the somewhat paradoxical fact that desalination produces a high-saline waste stream that can be difficult to dispose of, especially for processing plants located a distance from the coast.

The WaTeR Center is involved in a number of experiments, but one of the most exciting will play out in the desert in Yuma, Ariz., where the Metropolitan Water District of Southern California is preparing to fire up a small demonstration plant to test a technology developed in Cohen's lab.

Cohen's technology is called "accelerated precipitation" and aims to achieve a 95 to 98-percent recovery of freshwater out of brackish water from the nearby Colorado River. The Colorado, the source for about half of Southern California's water, is growing increasingly salty due to agricultural and urban runoff. If the Yuma experiment is successful, the troublesome discharge stream would be only 2 to 5 percent of the input water — an amount so small it's practically unheard of in real-world membrane desalination applications. The process showed promise in Cohen's lab but the real test will come in the desert.

The technology would be used in a massive desalination plant that the Metropolitan Water District hopes to construct in coming years, probably along the Colorado River Aqueduct, says Christopher Gabelich M.S. '96, D.Env. '01, an environmental specialist with the Metropolitan Water District. The plant would produce three times as much freshwater as the world's largest desalination plant, located on the Mediterranean in Ashkelon, Israel.

Despite its many problems, interest in RO desalination has surged in the past decade as supplies of freshwater have dwindled and scientists like those at UCLA have produced incremental improvements in the technology. RO membrane desalination today is a $45-billion-dollar industry, with thousands of plants around the world. Most are in the oil-rich Arabian Peninsula. Texans make drinking water from the briny Brazos River using RO. The Florida Keys turns seawater into potable water through RO technology. RO is such an effective treatment that it can also be used to treat municipal wastewater and agricultural drainage water.

The state Department of Water Resources estimates that California will depend on desalinated water for 6 to 8 percent of its needs, which means that scientists like Cohen, Hoek and Glater have their work cut out for them. California currently has 23 desalination plants, most of them using RO technology, but they produce only a negligible amount of water. Some are small; others are hardly used at all. The city of Santa Barbara built an RO plant during the drought of the early 1990s, but due to high production costs, the plant sits idle until the next water emergency.

Another two dozen or more plants are in design-and-construction or drawing-board stages. The largest will be in Long Beach, where the city is preparing to test an unusual desalination process that would use significantly less energy than conventional methods.

Water Breakthrough in Westwood

What few people outside the desalination world know is that the technology behind RO membrane desalination was born at UCLA. The scientist recognized as the grandfather of the RO membrane process is Sidney Loeb M.S. '59, Ph.D. '64, who was a UCLA doctoral student when he and fellow graduate student Srinivasa Sourirajan serendipitously discovered an effective way to make RO membrane desalination effective.

"Come on, I want to show you something," Glater says, walking briskly to a lab in Boelter Hall where Loeb worked late into the night developing UCLA's celebrated RO membrane process.

Published Jul 1, 2006 12:00 AM