| Orange County Water District's (OCWD's) Water Factory 21 (WF-21) is a wastewater reclamation plant that has practiced indirect potable water reuse since 1975. OCWD plans to expand the facility and improve water quality by replacing WF-21 with the Groundwater Replenishment (GWR) System. The GWR System will incorporate advanced water treatment technologies, including microfiltration, reverse osmosis (RO), and ultraviolet (UV) radiation.; N-Nitrosodimethylamine (NDMA) is a low molecular weight organic and possible human carcinogen detected in RO permeate at WF-21. The degree of NDMA destruction and the cost-effectiveness of several treatment methods were evaluated at OCWD to determine process feasibility for GWR System implementation.; Testing results indicate RO alone does not adequately remove NDMA. Testing of low- and medium-pressure UV systems reveal that UV treatment is effective in achieving NDMA regulatory compliance. Further, the use of hydrogen peroxide may improve UV performance and limit NDMA reformation. |
