Biofilm Fouling of RO Membranes—Its Nature and Effect on Treatment of Water for Reuse

Increasing demand for domestic water has spurred renewed activity in the treatment of secondary municipal effluent to augment existing resources. Demineralization of pretreated wastewater by reverse osmosis yields safe, potable supplies, but microorganisms 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 an advanced wastewater treatment plant in Southern California under low‐ and high‐chlorine conditions, where close relationships were found between the accumulation of biochemical material and the loss of membrane premeability. High chlorine residuals damaged the membrane structure and reduced mineral rejection capacity.