New Desalination Method Reduces Energy Costs

Located along the beautiful shores of the Pacific Ocean just south of Los Angeles, the city of Long Beach is home to about 500,000 people with ever-increasing needs for potable water. Local officials are working diligently to meet those needs by expanding their research into desalination.
Last November, the Long Beach Water Department, Los Angeles Department of Water and Power, and United States Bureau of Reclamation broke ground on a 300,000 gpd prototype seawater desalination facility at the Haynes Generating Station in Long Beach.
Earlier this year, the Long Beach Water Department awarded the construction contract for the prototype plant to Pascal & Ludwig Constructors and hired CH2M Hill as the construction manager.
Long Beach received the final permit for the project from the Los Angeles Regional Water Quality Control Board in June.
“The project was a design/build, so they spent the first few months finalizing the design…They mobilized on the site in June, and construction is now expected to be complete early next year,” explained Kevin Wattier, general manager of the Long Beach Water Department.
The Long Beach Seawater Desalination Research and Development Facility will be the nation’s largest seawater desalination research facility, and work done there will be vitally important to the advancement of desalination technology.

Unique method saves energy

Research conducted at the prototype plant will further develop a proprietary technology known as the Long Beach Method. Invented by Diem Vuong, assistant general manager at the Long Beach Water Department, this innovative method has proven to be 20% to 30% more energy efficient than conventional desalination methods such as reverse osmosis.
In conventional desalination, seawater is pushed through a single membrane at pressures of approximately 1,000 psi, whereas the Long Beach Method utilizes two membranes at lower pressures.
To prepare for the Long Beach Method, seawater passes through a preliminary filter to remove suspended materials. It is then pumped on to begin the main, two-stage process.
Stage 1: Filtered seawater is pumped at 525 psi through a nanofiltration membrane, which allows the water molecules to pass through, along with only the very smallest of salt molecules (12% of the initial amount of salt).
Stage 2: The water resulting from the first stage is pumped, under lower pressure of 250 psi, through a second nanofiltration membrane—blocking virtually all of the remaining salts.
The process produces high-quality potable water that meets or exceeds all state and federal standards for safe drinking water while resulting in significant energy savings over more widely employed methods.

Three-phase research to span decade

As the first phase in its applied research project, Long Beach Water has been operating a small-scale model of the two-stage nanofiltration pilot plant since October 2001.
“We have been operating a pilot plant for over two years, which proves to us that the science works as we thought. And now with this prototype plant, we are taking the technology out into the real world, still in a test mode, to make sure what we have demonstrated in the pilot studies still works,” Wattier said. “This prototype project will give us the information we need to bring a full-scale seawater desalination plant into our portfolio by around 2010.”
The prototype seawater desalination facility Wattier described is the second phase of the project. When the plant begins operation next year, officials will focus on several
key objectives:

  • Develop accurate information on total capital and operating costs;
  • Develop information needed for permitting a large-scale desalter;
  • Optimize Diem Vuong’s two-stage nanofiltration process; and
  • Refine the community-based model.

As for the method to be used for brine disposal, seawater will be separated into a potable water stream and a brine stream. Then the two streams will be recombined to form seawater and discharged back into the source channel.
As this decade comes to an end, Long Beach officials will begin the final phase in the program. A full-scale plant will begin operation, applying knowledge gained through research and development at the prototype plant. Once in full production, the plant will be capable of supplying 10% to 15% of Long Beach’s water needs—enough to compensate for planned reductions in Colorado River water purchased from the Metropolitan Water District of Southern California.
“What I think is significant is the stepwise approach to developing new technology and adding seawater to our water supply portfolio in Long Beach,” Wattier said.

Feds help fund desalination

Currently, there are more than 800 desalination plants operating nationwide with a capacity of 225 mgd, and the demand keeps right on growing.
Most are located in California, Texas and Florida. The desalination market is expected to generate expenditures of $95 billion from 2005 to 2015, primarily in the Middle East.
Congressional funding authority for the Long Beach Desalination Project was granted in the Reclamation, Recycling and Conservation Act of 1996. Under this funding authorization, the United States Bureau of Reclamation will pay 50% of the total cost of any desalination program. The total projected cost of building the Long Beach Research and Development Facility is about $8 million.
The federal government already has appropriated $2.7 million toward the project. An additional $1.5 million is in the FY2005 Energy and Water Appropriations bill which recently passed the House of Representatives. The Senate is expected to take up their version of the bill sometime close to presstime.
“This project takes time and money, and we are pleased that the federal government is assisting us with the financing … The Los Angeles Department of Water and Power has also been a tremendous partner on this project,” Wattier noted.
“We are committed to doing the necessary work to understand all the technical, operational, economic and environmental issues regarding seawater desalination so that we can make the best decision for the residents of Long Beach.”

For further information, visit www.lbwater.org.

Denise Covelli is editor of WWD.

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