SEWAGE TREATMENT METHOD

PROBLEM TO BE SOLVED: To solve the problem that in dynamic filtration, particles of activated sludge become small to be dispersed when a water temperature lowers to 15°C or lower or the load of sludge becomes high or low and, therefore, a favorable dynamic filter bed is not formed and a filtrate flow rate is lowered by the deterioration of the quality of treated water or the clogging of filter cloth. SOLUTION: A dynamic filtering method is constituted so that filter cloths for permitting the activated sludge to pass are provided in a biological reaction tank having an air diffusion pipe arranged therein in a dipped state and a filter body provided with a filtered water taking-out port is immersed in the falling flow of turning flow formed by the air diffusion of the air diffusion pipe to be arranged therein to form activated sludge layers on the surfaces of the filter cloths, and the activated sludge mixed liquid is filtered to take out filtered water. In this method, polymeric flocculant is added to raw water to be treated and/or the reaction tank. COPYRIGHT: (C)2003,JPO