Application of tubular membranes for surface water treatment: effect of membrane properties and operation modes

Filtration characteristics in surface water treatment using tubular microfiltration and ultrafiltration membranes made of polypropylene or ceramic were investigated. A series of filtration experiments were performed to examine the flux behaviors and fouling propensity. When the initial flux was set to be same, the fouling rates were similar regardless of the membrane materials and pore size, suggesting that the hydrodynamic effect was dominant compared with physicochemical interactions between foulants and membranes. Based on theoretical analysis of critical flux, the major foulants were identified to be colloidal particles which size ranges from 0.01 to 0.1 mu m. To control the membrane fouling, three methods were compared including (1) periodic backwashing; (2) intermittent operation (periodic pump stop); and (3) the mixed operation of dead end and cross-flow modes. Considering the anti-fouling effect and energy consumption, the mixed operation of dead end and cross-flow modes was better than other operation methods.