Hydraulic effects on sludge accumulation on membrane surface in crossflow filtration

Membrane filtration technology for application of wastewater treatment has been developing recently. In the application to wastewater treatment, it is major concern to remove cake layer on membrane surface effectively with crossflow shear stress. Hydraulic effect of sludge accumulation process on membrane surface in bubble and non-bubble driven crossflow filtration was studied. Maximum sludge accumulation, sludge accumulation rate, and lag phase were introduced to describe sludge accumulation process, and the effects of hydraulic conditions were clarified experimentally. Maximum sludge accumulation and sludge accumulation rate were dependent on aeration intensity, and were less depend on flow channel width and MLSS concentration. Their tendencies were explained by shear stress. Shear stress was thought to be the major hydraulic factor that influences them. Lag phase was dependent on aeration intensity, flow channel width, and MLSS concentration. A non-dimensional equation was proposed to explain dependencies of flow channel width based on consideration of hydraulic behavior of MLSS particles and shear stress. (C) 2001 Elsevier Science Ltd. All rights reserved.