Effect of Pre-Coating Powdered Activated Carbon on Water Quality and Filtration Resistance of MF Membrane Process for Treating Surface Water

This study evaluated powdered activated carbon (PAC) pre-coating as a pretreatment strategy to enhance dissolved organic matter (DOM) removal and control fouling during microfiltration of surface water. Two PAC types (one is coal-based and the other is wood-based), divided into three different particle size ranges (22–44, 44–63, 63–88 μm) using sieves and coating weights ranging from 0.6 to 1.2 and 2.4 mg/cm2, were systematically compared. Coating PAC improved the quality of water after filtration and stabilized filtration flux, with smaller PAC particle size ranges exhibiting higher DOM removal efficiencies, achieving maximum removals of approximately 30–35% for DOC and over 50% for UV260 at the highest coating weight, whereas uncoated membranes showed negligible DOM removal. The resulting PAC layer on the membrane increased filtration resistance. Fluorescence EEM and Mw distribution results showed that aromatic and high molecular weight DOM was preferentially adsorbed by PAC before reaching the membrane surface; therefore, their contribution to membrane fouling could be reduced. SEM observations showed differences in the images of deposits formed on the PAC layer. These results indicate that the PAC layer acted as a protective interception zone that reduced direct contact between DOM and the membrane surface, thereby contributing to improved flux stability. The coating effect varied with the weight, type and size range of PAC, highlighting the importance of PAC selection. The findings of this study could contribute to more efficient and sustainable urban water supply system operation and management through water quality improvement and process configuration.