Biofouling control by UV/H2O2 pretreatment for brackish water reverse osmosis process

Abstract

UV applied with H₂O₂ is a well-known advanced oxidation process (AOP) for degradation of trace organic compounds. However, the UV/H₂O₂ process has scarcely been documented as a disinfection method for brackish or seawater applications or particularly as a potential reverse osmosis (RO) biofouling control tool in varied treatment scenarios. The objective of this paper is to evaluate the potential of medium-pressure (MP)-UV/H₂O₂ as a pretreatment step to control brackish water RO (BWRO) biofouling caused by indigenous microorganisms. UV/H₂O₂ pretreatment significantly reduced total heterotrophic counts. Consequently, the quantity of biofilm cells and extracellular polymeric substances (EPS) following UV/H₂O₂ pretreatment was significantly lower than that obtained after the control and the singular UV pretreatment steps. This is attributed to the additive or synergistic effect of MP UV light, H₂O₂ and ˙OH radicals. Hence, UV/H₂O₂ has a high potential as a biofouling control tool in BWRO desalination systems. Higher H₂O₂ concentrations may achieve improved biofouling control due to enhanced radical formation and higher H₂O₂ residual effect.