AWWA MTC53845

The Long Beach Water Department (LBWD), serving a community of 440,000 within the City ofLong Beach, California, conducted a series of nanofiltration (NF) membrane selection tests forthe treatment of highly-colored groundwater. The testing was performed in anticipation of futuredrinking water quality regulations, including more stringent disinfection byproduct (DBP)regulations, and as part of the treatment process for bottling water.The groundwater is presently pumped and treated through LBWD's 62.5 million gallons per day(mgd) conventional filtration plant. There are 26 different wells located within the city, and thewells vary with respect to water quality. Most wells contain high levels of color andtotal organic carbon (TOC) that can result in high DBP formation if not removed prior tochlorination. The groundwaters also contain moderate concentrations of total dissolved solids(TDS), but not sufficient to make removal necessary.Similar to other utilities, LBWD provides bottled water to its consumers during interruptions inservice (e.g., main breaks). A plan for bottling Long Beach's treated groundwater was initiatedin 1998 to replace the commercial bottled water purchased for this purpose. The proposedbottling plant would use membranes for color and organics removal, followed by ozonation fordisinfection (limiting DBP formation) followed by the bottling equipment. The Osmonics DesalHL8040F membrane was selected from the membrane screening tests, and a 50 gallon perminute (gpm) nanofiltration unit has been operating since March 2000, providing water for thebottling plant.LBWD's testing goal is to select a membrane that can achieve the following:maximization of TOC removal; minimization of total dissolved solids (TDS) removal; and,operation at a pressure of 100 pounds per square inch (psi), or less.Additionally, the membrane plant will also serve as a training facility for operators for futuremembrane projects being planned by LBWD. The membrane-selection phase was conductedbetween March to July 1998. Includes 3 references, tables, figures.