Effects of clay on the fouling by organic substances in potable water treatment by ultrafiltration

In water treatment by ultrafiltration, effects of clay on the fouling due to organic matter in cross-flow ultrafiltration were evaluated by fouling model materials and clay. Fouling model materials selected were BSA (Bovine serum albumin, MW68,000), Dextran (MW70,000), and humic acid (MW8,000-200,000) at a size larger than molecular weight cut-off (MWCO 50,000, polysulfone) and alpha-lactalbumin, Dextran (MW9,300), fulvic acid (MW8,000) for smaller size than and that kaolin was selected as a clay material. The flux of BSA, Dextran (MW70,000) increased with an increase in the amount of kaolin, and the flux of alphalactalbumin, Dextran (MW9,300), fulvic acid did not increase with kaolin. In contrast, the flux of humic acid decreased with an increase in the quantity of kaolin. It was found that in the direct ultrafiltration of river water clay materials did not affect the flux decline, and could contribute to the prevention of fouling due to organic matter. It seemed that the pore size of membrane plays an important role in the effect of clay on the fouling due to organic matter.