Membrane Fouling Minimization by a Magnetic Ion Exchange (MIEX®) Resin

摘要

Two challenges of low-pressure membrane (LPM) filtration are low dissolved organic matterrn(DOM) rejection and membrane fouling by DOM. In recent years, the magnetic ion exchangern(MIEX®) resin (Orica Watercare, Australia) has proven effective in removing DOM in manyrnsource waters, and therefore MIEX can potentially minimize LPM fouling. In this study, twornnatural waters and one synthetic water with a wide range of dissolved organic carbon (DOC)rncontent were examined in fouling experiments with a polyvinylidene fluoride (PVDF) hollowrnfiber ultrafiltration (UF) membrane. Results showed that MIEX pretreatment decreased thernfouling potential of the waters tested to various degrees, as indicated by unified membranernfouling index (UMFI) values 12-56% lower for MIEX-treated waters than for raw waters. MIEXrnwas found to be effective in removing DOC in all waters (i.e., 38-83% DOC removal with a resinrndose of 2 mL/L), but the extent of DOC removal did not correlate with the extent to which thernresin minimized membrane fouling. DOM characterization results revealed that protein-likernfluorophores fouled the membrane more than humic-like fluorophores and MIEX preferentiallyrnremoved the latter fraction, which is not the main fraction causing LPM fouling. As a result,rnoptimizing the MIEX resin to remove more of the protein-like fraction of organics wouldrnenhance its ability to reduce membrane fouling.