Removal of natural organic matter using iron oxide-coated membrane systems

Natural organic matter (NOM) removal and membrane fouling were investigated using iron oxide-coated microfiltration (MF) systems for drinking water treatment. Addition of iron oxide particle (IOP) adsorbents into MF always improved NOM removal and reduced fouling, but IOP dosing methods did affect the membrane performance. The IOP coating layer formed on the membrane surface played a major role in preventing membrane fouling by residual NOM in water. Pre-mixing of IOP with raw water followed by continuous injection into the MF system controlled membrane fouling better than pre- and intermittent loadings of IOP. This could be in close association with the distribution of IOPs across the hollow fiber MF surfaces and the effectiveness of contact of IOP with feedwater. The turbidity of water influenced the MF system with intermittent IOP loads more greatly than that with IOP in suspension. There existed an optimal IOP dose where membrane fouling can be minimized achieving maximal NOM removal.