抄録
Effects of the ratio of molecular weight (MW)/molecular weight cut-off (MWCO) on the flux of organic substance and clay in ultrafiltration were evaluated by fouling model materials and clay. Fouling model materials selected were protein (BSA, α-lactalbumin, γ-Globulin), polysaccharide (MW9,300, 70,000, 250,000, 515,000), fulvic acid (NW8,000) and humic acid (MW8,000-200,000, 8,000-50,000, 8,000-10,000, c.a200,000), and kaolin was selected as a clay material. The polysulfone membrane (MWCO10,000, 50,000 and 200,000) were used as an ultrafiltration membrane.
The flux of protein and polysaccharide with coexistence of kaolin increased in the case of the ratio of MW/MWCO being greater than one, but ded not increase in the case of the MW/MWCO ratio being below one. In contrast, the flux of fulvic acid and humic acid with coextence of kaolin decreased regardless of the ratio of MW/MWCO.
The addition of dispersion agent and coagulant in the organic substances and kaolin mixture solution changed the size distribution of kaolin, and resulted in the change of the flux. When the transmembrane pressure was changed from 100kPa to 200kPa, the flux of BSA and humic acid decreased with coextence of kaolin.
It was suggested that the decline of the flux with coexistence of kaolin was due to the change of the resistance of kaolin cake layer corresponding the change of kaolin size distribution with charge and filtration pressure.
