AWWA MTC57614

Orange County Water District (OCWD) began operation of Water Factory 21 in Fountain Valley, 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 that Water Factory 21 is nearing the end of its useful life, OCWD is planning the Groundwater Replenishment (GWR) System as its replacement. The GWR System will use 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 to qualify 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 offer additional benefits to the project. West Basin Municipal Water District (WBMWD), similar to OCWD, has been in the forefront of reclamation having installed a conventional pretreatment system including lime clarification, recarbonation and filtration ahead of RO in 1995 for supplementing the seawater intrusion barrier. Subsequent to that, WBMWD was the first agency to install full-scale MF and RO facilities for treating secondary wastewater effluent for injection into the seawater intrusion barrier at the West Basin Water Recycling Plant in El Segundo, CA in July 1997. Since that time, WBMWD has continued to expand their water reclamation and recycling facilities and have installed three additional MF/RO systems with a combined capacity of approximately 25 mgd. Since the installation of the existing MF/RO systems, WBMWD has continued to perform additional RO membrane pilot tests to determine the operating parameters and characteristics of the membranes. WBMWD is continually looking for the next membranes that will offer lower operating costs with better salt rejection. Both agencies recently conducted independent studies to determine if the latest RO membranes to hit the market, which claimed to be low fouling or fouling resistant membranes, actually achieved better operating characteristics and lower operating pressures than previous thin film composite membranes. In 2001-2002, OCWD tested three low fouling membranes on microfiltered secondary effluent from Orange County Sanitation District. In 2001-2002, WBMWD under a research grant, operated two different low fouling membranes in parallel for a period of seven months; and compared the performance of these membranes with regular thin film composite membranes on full-scale MF/RO facilities. This paper focuses on OCWD and WBMWD and why both agencies continue to pilot test 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 low fouling membranes did not operate at lower operating pressure than the previous membranes. Additionally, the paper focuses on the differences in the fouling characteristics of RO membranes for two different wastewater sources. Includes 2 references, tables, figures.