AWWA MTC64532

The Long Beach Water Department (LBWD), similar to many Southern California utilities, has been facing the issue of decreased potable water supplies. Because of its location, the City of Long Beach is ideally situated to take advantage of desalinated seawater as a source of drinking water and is interested in incorporating desalinated seawater into its potable water portfolio. However, before seawater desalination can become a reality, additional advances are needed to further reduce the cost of desalination. LBWD is currently exploring feasibility of using nanofiltration membranes (NF) in a dual-pass configuration to evaluate the possibility of achieving additional cost reduction as well as meeting all water quality objectives. To provide clear and quantifiable answers to water quality and O&M questions related to the traditional seawater reverse osmosis (SWRO) versus dual-pass nanofiltration process, LBWD has formulated an aggressive research program and constructed a 300,000 gallons per day permeate "Prototype" research facility using full-scale equipment. This paper presents LBWD's preliminary evaluation of SWRO and initial comparisons against dual-pass nanofiltration. Includes 11 references, tables, figures.