SEWAGE TREATMENT METHOD

PROBLEM TO BE SOLVED: To solve the problem that in dynamic filtration, sludge concentration equipment must be arranged before anaerobic treatment or dehydration treatment when the concentration of excess sludge is not more than 3,000 mg/L and, when the concentration of the activated sludge mixed liquid in a reaction tank becomes high, the filtering flow rate of the filter body must be set low and filter equipment is increased. SOLUTION: A dynamic filteration method is constituted so that filter cloths permitting the activated sludge to pass are provided in a biological reaction tank having an air diffusion pipe immersed and arranged therein and the filter body provided with a filtered water taking-out port is immersed and arranged in the falling flow of turning flow formed by the air diffusion of the air diffusion pipe to form activated layers on the surfaces of the filter cloths and the activated sludge mixed liquid is filtered to take out filtered water. In this method, a filter device divided into a filter part and a concentration part is used in the biological reaction tank to reduce the filtrate flow rate of a concentration part as compared with a filter part not only to make equipment compact but also to increase the concentration of the excess sludge drawn out of the reaction tank. COPYRIGHT: (C)2003,JPO