Hybrid water treatment process of tubular carbon fiber ultrafiltration and photocatalyst-coated PP beads: treatment mechanisms and effects of water back-flushing time

Abstract

The effect of water back-flushing time (BT) on membrane fouling and treatment efficiency was investigated in a hybrid process of tubular carbon fiber ultrafiltration (UF) and titanium dioxide photocatalyst-coated polypropylene beads for advanced water treatment, and compared with the previous study utilizing alumina or carbon UF membranes. The resistances of membrane fouling (Rf) were highly affected by BT, and Rf decreased significantly as increasing BT. The water back-flushing prohibited membrane fouling more efficiently for the carbon fiber UF than the alumina UF. The BT did not affect the turbidity treatment in this hybrid process; however, the turbidity treatment efficiency was maximal at no back-flushing, and increased dramatically as increasing BT in the hybrid process utilizing alumina UF. The treatment efficiency of dissolved organic matters (DOM) was maximal at BT of 30 s, and increased dramatically as increasing BT. The adsorption and photo-oxidation by the PP beads and UV could not play important roles in turbid matters treatment of the hybrid process utilizing the carbon fiber or carbon UF membranes; however, the role of adsorption was significantly dominant in the hybrid process utilizing the alumina UF. Additionally, the adsorption and photo-oxidation could play more dominant roles in the DOM treatment of the hybrid process utilizing the alumina UF than those utilizing the carbon fiber or carbon UF.