Optimizing RO Design Criteria for Indirect Potable Reuse

Abstract

With Southern California's imported water supplies becoming more unpredictable, the city of Los Angeles, Calif., has begun an aggressive campaign to secure a more reliable water supply through conservation, recycling, stormwater capture, and improvements to local groundwater resources. As part of this effort, the Los Angeles Department of Water and Power partnered with the Los Angeles Department of Public Works to develop a Recycled Water Master Planning effort, which has included the commissioning of a groundwater replenishment treatment pilot study at the Donald C. Tillman Water Reclamation Plant. The pilot study included testing and evaluation of a proposed primary treatment process, consisting of microfiltration followed by reverse osmosis (RO) and advanced oxidation to destroy trace organic compounds. Testing began in February 2010 and was completed in June 2011. This article provides an overview of operating conditions in several southern California wastewater RO facilities, discusses the significance of test conditions evaluated for the Los Angeles project, and presents pilot-testing results.