Water Reuse for Drought-proof Industrial Water Supply in San Diego

About the author: For further information, contact Pall Corporation, Port Washington, NY Phone 516-484-3600 www.pall.com/water

A 200,000 gallon per day (gpd) advanced microfiltration system treats secondary wastewater effluent for reuse as process water for Toppan Electronics, Inc. in San Diego, Calif. The treated water replaces potable water purchased from the San Diego water system. Secondary wastewater effluent is always available as a source of water in water-short southern California.

The new microfiltration equipment is a Pall AriaSM small flow system, which provides consistently high removals of solids, pathogenic cysts, and bacteria from the secondary effluent, to provide the right type of feed water to Toppan’s existing reverse osmosis (RO) system. Testing at other water reuse facilities has shown that microfiltration significantly improves RO system operation by increasing allowable fluxes by 20%; reducing operating costs by 40%; and increasing the interval between chemical cleanings for the RO system by four times compared to conventional lime settling and filtration of secondary effluent.

The compact Aria system allowed the 200,000 gpd microfiltration unit to be installed in a small space outside a building and under a landing. The system has been successfully operating since May 2000 and is providing high quality feed water for the RO system.

The low installed cost means that the cost of reused water is similar to the cost of purchased potable water. Jerry Barnes, president of Toppan, is very pleased with the result and said, "Water reuse using the Pall Aria system helps the environment by conserving precious supplies of potable water, while giving Toppan an economical water supply to keep operating even during droughts."

Clark Dawson, a local consultant instrumental in getting this installation off the ground, added, "This system delivers some of the cleanest water on the planet, made from some of the dirtiest water — sewage."

The Pall Aria system is a compact, skid-mounted microfiltration unit available in three capacities — 60, 175 and 350 gpm. The compact design allows the units to fit through a standard 3-ft. door to simplify installation at existing facilities.