FOULING IN TANGENTIAL-FLOW ULTRAFILTRATION - THE EFFECT OF COLLOID SIZE AND COAGULATION PRETREATMENT

The fouling characteristics of dispersions of dissolved organic materials and colloids are investigated in a series of ultrafiltration experiments. Dispersions of tannic acid, humic acid and kaolin are filtered using a cross-flow hollow fiber module. In some cases these materials are modified through the addition of a polymeric aluminum coagulant. The flux characteristics of these dispersions, ranging in particle size from several nanometer to several hundred micrometer, are in qualitative agreement with theory; particles near 0.2μm in diameter produce rapid fouling, while particles greater than 3 μm in size have little effect on flux. Coagulation of the model dispersions is effective in maintaining membrane flux. However, coagulation pretreatment of Seine River water produced smaller improvements in membrane flux. © 1990.