AWWA JAW10946

Water Factory 21, an advanced wastewater treatment facility in Orange County, California, reclaims approximately 57 ML/d (15 mgd) of activated sludge, treated effluent from the Orange County Sanitation Districts. Demineralization of pretreated wastewater by reverse osmosis yields safe, potable supplies, but micro-organisms and chemical substances in the feedwater rapidly impede membrane flux, reducing plant efficiency and increasing treatment costs. The nature of biofilm development was studied at Water Factory 21 under low and high chlorine conditions. Close relationships were found between the accumulation of biochemical material and the loss of membrane permeability. High chlorine residuals damaged the membrane structure and reduced mineral rejection capacity. Includes 30 references, table, figures.