Electro-microfiltration treatment of water containing natural organic matter and inorganic particles

Natural organic matter (NOM) and inorganic particles are ubiquitous in many natural surface waters that serve as sources of drinking water. In addition to reacting with chlorine to form chlorinated disinfection by-products (DBPs), NOM and NOM sorbed on inorganic particles cause serious membrane fouling problems. We evaluated the feasibility of using a novel laboratory-scale electro-microfiltration (EMF) system to remove NOM and inorganic particles from water. Synthetic water samples containing 5 mg/L humic acid (HA) only (Kao0), 5 mg/L HA and 5 mg/L kaolin (Kao1), and 5 mg/L HA and 50 mg/L kaolin (Kao2) were used in the EMF study. Kao2 demonstrated the largest flux decline in the absence of an electrical field. When an electrical field was applied, the filtration flux, NOM removal, and decrease in specific ultraviolet absorbance (SUVA) were enhanced because of electrophoretic and electroosmotic effects. When the applied electrical field strength was greater than a critical electrical field strength (Ecritical), system operations and efficiency did not increase further. These results suggest that the applied electrical field should be close to Ecritical for maximum efficiency and cost-effectiveness. This study demonstrates that an EMF system is a highly effective way to treat water containing NOM and inorganic particles.

Research Highlights
► EMF system is a highly effective way to treat NOM and inorganic particles in water.
► Filtration flux, NOM removal, and SUVA reduction were enhanced during EMF system.
► Electrophoresis and electroosmosis were the main mechanisms in EMF system.