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Orange County Water District (OCWD) began operation of Water Factory 21 in FountainValley, California in 1976, which uses a three stage pretreatment process ahead of reverse osmosis (RO)to reclaim secondary effluent from the Orange County Sanitation District. Now thatWater Factory 21 is nearing the end of its useful life, OCWD is planning theGroundwater Replenishment (GWR) System as its replacement. The GWR System willuse microfiltration (MF) as pretreatment to RO followed by Ultraviolet (UV) Irradiation.As part of the project, OCWD has been testing thin film composite RO membranes toqualify them for the GWR System, which will have a RO capacity of 70 mgd.Additionally, OCWD has tested low fouling membranes to determine if they would offeradditional benefits to the project.West Basin Municipal Water District (WBMWD), similar to OCWD, has been in theforefront of reclamation having installed a conventional pretreatment system includinglime clarification, recarbonation and filtration ahead of RO in 1995 for supplementing theseawater intrusion barrier. Subsequent to that, WBMWD was the first agency to installfull-scale MF and RO facilities for treating secondary wastewater effluent for injectioninto the seawater intrusion barrier at the West Basin Water Recycling Plant in ElSegundo, CA in July 1997. Since that time, WBMWD has continued to expand theirwater reclamation and recycling facilities and have installed three additional MF/ROsystems with a combined capacity of approximately 25 mgd. Since the installation ofthe existing MF/RO systems, WBMWD has continued to perform additional ROmembrane pilot tests to determine the operating parameters and characteristics of themembranes. WBMWD is continually looking for the next membranes that will offerlower operating costs with better salt rejection.Both agencies recently conducted independent studies to determine if the latest ROmembranes to hit the market, which claimed to be low fouling or fouling resistantmembranes, actually achieved better operating characteristics and lower operatingpressures than previous thin film composite membranes. In 2001-2002, OCWD testedthree low fouling membranes on microfiltered secondary effluent from Orange CountySanitation District. In 2001-2002, WBMWD under a research grant, operated twodifferent low fouling membranes in parallel for a period of seven months; and comparedthe performance of these membranes with regular thin film composite membranes onfull-scale MF/RO facilities.This paper focuses on OCWD and WBMWD and why both agencies continue to pilottest RO membranes before and after their projects are completed. The paper addresses the results of the testing from both agencies, which have shown that the lowfouling membranes did not operate at lower operating pressure than the previousmembranes. Additionally, the paper focuses on the differences in the foulingcharacteristics of RO membranes for two different wastewater sources. Includes 2 references, tables, figures.

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Edition: Vol. - No. Published: 03/05/2003 Number of Pages: 18File Size: 1 file , 430 KB