Ultrafiltration membrane have been studied of its application to activated sludge process, regarding the filtration rates as functions of membrane pore size, pressure difference, liquid velocity of direction along membrane surface, mixed liquor viscosity, and MLSS concentration. The membrane module investigated was of plate type.
Under high MLSS concentration, the activated sludge accumulates on the membrane surface and depressed the filtration rate, because of the increase in mixed liquor viscosity. The behavior of viscosity of the mixed liquor was found to be formulated similarly to the high polymer solution.
The Ruth equation can be applied to the filtration rate for the membrane pore size of 50000 molecular weight and under, while for pore size of 10, 000 and more it needs modification in term of pore clogging. The optimum pore size for the activated sludge system was found to be of 50, 000.
