xBoth the fouling mechanisms and the regeneration of two asymmetric microporous Al2O3 MF membranes for the recovery of fine TiO2 particles in acid wastestreams were investigated. The fouling was mainly caused by particle deposition, ion adsorption, and gel polarization. The foulants include TiO2 particles and sulfates. The effect of operation conditions including membrane pore size, transmembrane pressure, and cross-flow velocity (CFV) on the fouling were also investigated, and the appropriate conditions were obtained. Membrane regeneration was achieved by backpulsing and chemical cleaning. Backpulsing is an effective method for reducing fouling extent of 1.0 mum pore-size membrane. The optimum backpulsing conditions are also determined. The effective cleaning agent is 0.5 mol/l oxalic acid solution.