Energy-efficient desalination technology receives patent protection

LONG BEACH, Calif.—The U.S. Patent Office (USPTO) recently issued a Notice of Allowance for Patent Protection for a seawater desalination process developed by Long Beach Water Department engineers. According to the department, the two-stage, nanofiltration process—or Long Beach Method, as it has become known—has been demonstrated to be 20-percent to 30-percent more energy efficient than reverse osmosis. The process is the subject of more intense research and development activity at the nation’s largest, fully functional seawater desalination research and development facility, located in Long Beach. The USPTO is expected to issue the patent in the first quarter of 2007; major foreign patents are still pending.

The Long Beach Method was developed by former Long Beach Water Assistant General Manager Diem Vuong, who retired last year but remains closely involved in the development of this technology as a consultant at the department’s seawater desalination facility. "The award of this patent is a true testament to the genius of Diem Vuong and to the depth of knowledge and innovation of one of the greatest engineering teams in the industry," stated Kevin L. Wattier, general manager of the Long Beach Water Department.

High operating costs, primarily because of high rates of power consumption, and environmental issues related to open-ocean intake and discharge have rendered seawater desalination cost- and environmentally prohibitive in Long Beach. According to Long Beach Water, significant advancements in technology have extended membrane life while lowering energy requirements, but overall energy consumption remains extremely high because of the high-pressure requirements of reverse osmosis membranes.

Using a small, 9,000-gallon-per-day, pilot-scale desalter, the Long Beach Water Department reduced the overall energy requirement (by 20 to 30 percent) of seawater desalination using a relatively low-pressure, two-stage, nanofiltration process—the Long Beach Method. With funding assistance from the U.S. Bureau of Reclamation and the Los Angeles Department of Water & Power, Long Beach Water currently is testing the process at a constructed, 300,000-gallon-per-day, fully operational facility. This large-scale facility is needed to verify the energy savings when using full-scale membranes and energy-recovery units, among other things. The goal is to verify energy savings of the two-stage, nanofiltration process and to optimize the process so that it can be duplicated.

Together with its funding partners, Long Beach Water is also undertaking design and construction of an under-ocean-floor intake and discharge demonstration system—reportedly the first of its kind in the world—that will seek to demonstrate that viable, environmentally responsive intake and discharge systems can be developed along the California coast.