SEWAGE TREATING APPARATUS

摘要

PROBLEM TO BE SOLVED: To surely obtain treated water having high water quality by specifying the ratio of the plane arrangement area of an aerator and the plane arrangement area of a filter body to a prescribed value or below, thereby making it possible to carry out efficient filtration without increasing filtration resistance with the filter body immersed and arranged within a reaction layer. SOLUTION: This sewage treating apparatus is constituted by forming the front stage side of an aeration layer 2 as an anaerobic zone 2A and the rear stage side as an aerobic zone 2B, immersing and arranging the aerator 3 and the filtration unit 5 into the aerobic zone 2B and disposing a sludge return pipe 10 for returning part of the separated sewage of the settling layer improving aeration layer 4A to the anaerobic zone 2A of the aeration layer 2. Since the sewage treating apparatus is capable of prolonging a biological treatment time and forming anaerobic and aerobic flow patterns, the aperture is capable of dealing with nitrogen removal by the function of denitrification and nitrification of nitrogen. The ratio SB/SF of the plane arrangement area SB of the aerator 7 and the plane arrangement area SF of the filtration unit 8 in at least the settling layer improving aeration layer 4A is specified to <=1.