Redondo Beach desalination test plant key to local efforts to convert ocean water to fresh water

The future of desalination in the South Bay lies in the back of Redondo Beach's SEA Lab science center, where a few rooms filled with a network of thick copper-alloy pipes filter a half-million gallons of sea water daily.

By the end of this year, the facility will be closed as efforts move forward to build a permanent $300 million desalination facility at the NRG power plant in El Segundo.

West Basin Municipal Water District officials opened the test desalination facility in 2010, after trying out the technology to freshen saltwater at a smaller site in El Segundo for about seven years. Since opening the Redondo Beach site, they have been studying the science of safely removing salt, ocean life and debris from saltwater to make it drinkable or otherwise useful to people.

Officials at West Basin, a water wholesaler primarily serving South Bay cities, say that in addition to relying on recycled and imported water, finding ways to make ocean water safe to drink, water lawns and process petroleum at oil refineries is key to the district's future.

"The one good benefit for ocean-water desalination is that it's drinkable water that's local and not affected by weather," said Ron Wildermuth, a spokesman for West Basin Municipal Water District. "Every Southern California water agency is localizing and diversifying their water supply."

A $1 billion water desalination plant in Carlsbad is now under construction and about a dozen other similar projects have been proposed along the California coast.

Critics of desalination argue that its high energy needs are too costly and that it is too destructive to ocean ecosystems, pointing to desalination facilities that have been shut down or inactive for years in Santa Barbara and on Catalina Island because they were too expensive.

But West Basin officials believe modern technology is helping to make desalination less costly. At the Redondo Beach test site, for example, operators have learned how to save energy costs by halting sea water intake during ocean conditions such as algal blooms, which render ocean water unsuitable for the desalination process.

Environmental studies also are in the works in Redondo Beach to better understand how the wedge-wire screens that initially filter the ocean water as it comes into the facility can better protect larvae and other ocean life that is inadvertently drawn in.

Desalination starts when the ocean water is passed through "ultra-filtration membranes." It then goes through a process called reverse osmosis, in which the water passes through stacks of paper-like filters.

"We have two passes here, a first and a second pass," Diane Gatza, an engineer with the district, said about the Redondo Beach facility's reverse osmosis system. "After we take the water through one pass of reverse osmosis, we take a small portion of it and put it through a second pass to get a little bit higher quality of water."

Because of the statewide drought, Northern California has blocked water transfers to Southern California, leaving communities to instead rely on their reserves and imported water from the depleted Colorado River. The West Basin district's water stores are plentiful for the next year or two, so mandatory water rationing has not been imposed.

But district officials are working to increase conservation efforts and find other sources of fresh water. The district distributes drinking and recycled water to a 185-square-mile area that includes South Bay cities as well Culver City and Malibu.

By 2020, the district plans to have an operational desalination plant that will produce 10 percent of its total water needs, reducing reliance on supplies from Northern California and the Colorado River. An environmental review process has been initiated to plan for a permanent South Bay site that will clean 20 million gallons of water a day.

"Our goal is to reduce imported water by 50 percent by 2020," Wildermuth said. "Right now, we're at 66 percent imported water and we want to be at 33 percent because of stresses on the water supply due to environmental restrictions, climate-change impacts, population growth and other challenges to our future water supply."

source

Media

Taxonomy

• Filtration
• Water Utility