Controlling disinfection by-products and organic fouling by integrated ferrihydrite–microfiltration process for surface water treatment

Controlling organic fouling and removing disinfection by-product (DBP) precursors remain challenges for the hybrid membrane process. Whether ferrihydrite (FH), an amorphous iron oxide, can achieve both targets when used as an adsorbent is unknown. Batch experiments of the integrated FH adsorption–microfiltration (MF) process were performed to study the effects of organic components on mitigating membrane fouling and reducing DBP formation, in comparison to powdered activated carbon (PAC). Both FH and PAC decreased the rate of initial organic fouling by removing DOM causing pore-fouling, which was probably polysaccharide-like compound. Afterwards, when cake fouling predominates, FH had smaller specific cake resistances than PAC. FH + MF was more effective for raw waters containing DOM with larger molecular sizes (>3 kDa) than PAC + MF. DBP formation potential in FH-treated waters is mostly lower than that in PAC-treated waters. This promotes a greater reduction of lifetime cancer risk from trihalomethanes (THMs) through the ingestion route when compared to MF and PAC + MF by lowering the formation potential of bromodichloromethane that produces a high unit risk among THM species. In general, FH exhibits better performance than PAC at small filtered volumes (