Effect of UV/ClO2 pretreatment on controlling ultrafiltration membrane fouling of different natural organic matter (NOM) fractions

The ultrafiltration membrane fouling caused by natural organic matter (NOM) is a prevalent problem. In this research, UV/ClO2 pretreatment was employed to control ultrafiltration (UF) membrane fouling induced by various components of NOM. Three typical organic model foulants, including humic acid (HA), sodium alginate (NaAlg) and bovine serum albumin (BSA) were used as representative organic components in natural waters, and their mixture was employed as simulated NOM water. The results showed that UV/ClO2 pretreatment was effective in alleviating membrane fouling induced by HA, NaAlg, BSA, and NOM, which was demonstrated by the enhanced hydrophilicity and interfacial free energy after UV/ClO2 pretreatment. Besides, it showed remarkable removal performance of UV254 and fluorescent components, but caused a deterioration of dissolved organic carbon (DOC) in the permeate, which was attributed to the oxidation of unsaturated organic compounds and reductive organic molecular weight (MW). Moreover, the significantly degradation of disinfection byproduct precursors (DBPs) and micro-polluted organic matter of sulfamethoxazole (SMX) were confirmed. With UV/ClO2 pretreatment, the dominant fouling mechanism in the initial stage of HA and NaAlg showed a tendency that pore blocking played a dominated role, which was opposite with BSA and NOM.