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In response to increasing demands for potable water in southern California, theOrange County Water District and Sanitation District of Fountain Valley,California, have developed a joint Groundwater Replenishment (GWR) System. Thisproject will treat secondary wastewater effluent, currently discharged to theocean, to produce high quality water for recharge of the Orange Countygroundwater basin and injection into a sea water intrusion barrier. Thethree-phase project, beginning in 2003, will ultimately produce 100,000 acre-feetper year by 2020. Phase 1 of the GWR project, with a capacity of about 80 milliongallons per day (mgd), has been conceptualized and the preliminary design hasbegun. Phase 1 adopts the add-on approach. Microfiltration (MF), followed byreverse osmosis (RO), is to be added on to the end of the secondary treatmentprocess to produce high-quality water for reuse. Phases 2 and 3 of the GWR systemproject, however, present a number of different challenges including a shortageof land, high costs associated with additional secondary wastewater treatmentfacilities, and the disposal of additional biosolids. A new treatment approachthat utilizes membrane processes in combination with anaerobic biologicaltreatment could alleviate such problems. The proposed approach utilizes the MFprocess to treat primary effluent followed by reverse osmosis (RO), ornanofiltration (NF), to concentrate soluble biological oxygen demand (BOD) andproduce a high quality effluent for reuse. The RO concentrate, which is free ofsuspended material, is then treated in a high-rate anaerobic digestion processthat eliminates the need for conventional secondary activated sludge treatment.This paper presents details of the process as well as preliminary pilot plantresults from continuous testing of the new treatment approach at Orange County. Includes 7 references, tables, figures.

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Edition: Vol. - No. Published: 01/01/2000 Number of Pages: 13File Size: 1 file , 530 KB