Developing a regional recycled water program in Southern California

Abstract

Abstract The Metropolitan Water District of Southern California (Metropolitan) and the Sanitation Districts of Los Angeles County (Sanitation Districts) are exploring the potential of a Regional Recycled Water Program (RRWP) to beneficially reuse water currently discharged to the Pacific Ocean. The program would consist of a new advanced water treatment (AWT) facility at the Sanitation Districts' Joint Water Pollution Control Plant (JWPCP) in Carson, California, USA, capable of producing an ultimate flow of 581 MLD (150 MGD). The full-scale facility would treat effluent from the JWPCP using an AWT train comprising a membrane bioreactor (MBR), followed by reverse osmosis (RO) and ultraviolet light advanced oxidation (UV/AOP). After MBR-RO-UV/AOP treatment, the treated water would be distributed to groundwater basins in Los Angeles and Orange counties to recharge their aquifers. This program would diversify the region's water resources and significantly contribute to long-term water supply targets outlined in Metropolitan's Integrated Water Resources Plan. A feasibility study for the RRWP was completed in 2016, confirming its technical viability. Currently, Metropolitan and the Sanitation Districts recently completed conceptual planning studies to investigate implementation options for a full-scale program, and constructed a 1.9 MLD (0.5 MGD) AWT demonstration facility. Although large facilities employing membrane filtration (MF)-RO-UV/AOP are currently permitted and operating in California, there are no facilities using an MBR-RO-UV/AOP train. The AWT demonstration facility – the Regional Recycled Water Advanced Purification Center – will build on recent research in Australia and the USA to develop a regulatory strategy to incorporate MBR into a potable reuse advanced treatment train.