Closed Circuit Reverse Osmosis (CCRO) for Treatment of RO Concentrate for Potable Reuse

The Orange County Water District (OCWD) Groundwater Replenishment System (GWRS) is the worldís largest potable reuse plant, treating secondary effluent to produce purified water for groundwater recharge as a drinking water supply augmentation and for injection into coastal wells that form a barrier to prevent seawater intrusion. Currently the GWRS has a production capacity of 100 million gallons per day (MGD), with the existing three stage, 85% recovery reverse osmosis (RO) system generating 18 MGD of RO concentrate that is discharged to the ocean. Upon completion of the final GWRS plant expansion in 2023, full production capacity will increase to 130 MGD while the RO concentrate flows will increase to 23 MGD. To further increase GWRS purified water production, OCWD has been exploring cost effective options to recover additional water from the RO concentrate and generate a new water supply for the region.