Effects of macro-porous anion exchange and coagulation treatment on organic removal and membrane fouling reduction in water treatment

Abstract

Macro-porous anion exchange, coagulation and their combination were used as pretreatment for microfiltration, and their effects on organic removal and membrane fouling reduction were evaluated. The experimental results showed that resin was effective in removing organics of medium and small molecular weight (MW), especially those of medium MW of UV absorbance, but was ineffective in removing organics with large MW. Using resin alone as a pretreatment removed organics effectively but was limited in its reduction of membrane fouling. With the combination of coagulation and resin as a pretreatment for microfiltration, not only were organics removed effectively, but membrane fouling was also reduced. Analysis of membrane surface with scanning electron microscopy (SEM), atomic force microscopy (AFM) and combined results of behaviors of MW distribution and flux indicated that biopolymer plays a key role in membrane fouling, and coagulation could remove this part of organics. Integrated coagulation and resin pretreatment by filtration columns were suggested for use in surface water prior to membrane filtration.