AWWA MTC57615

In order to supplement sources of water in Orange County, California, the Orange County Water District (OCWD) and the Orange County Sanitation District (OCSD) have developed the Groundwater Replenishment (GWR) System. This phased project will reclaim clarified secondary effluent and produce water for a seawater intrusion barrier and for groundwater recharge. The AWTF consists of three major treatment processes: microfiltration (MF); reverse osmosis (RO); and, an advanced oxidation process (AOP), which consists of ultraviolet (UV) light and hydrogen peroxide. Currently in the GWR System design, membranes operate in conjunction with advanced oxidation processes to provide treatment of wastewater. This multi-barrier approach produces water with quality higher than other sources available to the Orange County area. Due to increased awareness of new and emerging contaminants, OCWD and OCSD evaluated options to efficiently treat water that would meet all drinking water standards. Using a full-scale demonstration facility, it has been proven that removal of these contaminants below regulated levels is possible with the advanced treatment processes of MF, RO, and AOP. Concern has recently focused on the fate of low molecular weight organics (LMWOs) and pharmaceuticals during advanced treatment. LMWOs and pharmaceuticals have been sampled throughout the GWR demonstration facility. Preliminary results have demonstrated that RO followed by an advanced oxidation process (UV and hydrogen peroxide) is able to effectively remove these contaminants. The approach used at OCWD and OCSD to address these emerging contaminants is presented in this paper. Includes 12 references, tables, figures.