METHOD AND DEVICE FOR DENITRIFYING AND DEPHOSPHORIZING SEWAGE BIOLOGICALLY

摘要

PURPOSE:To remove a BOD component, nitrogen component and phosphrous component simultaneously, by subjecting mixed liquid of sewage contg. the respective components of BOD, nitrogen and phosphrous and return sludge to an anaerobic treatment then to a denitrification treatment and a nitrification treatment having a fixing means for living things. CONSTITUTION:Raw water and return sludge are mixed and are introduced into an anaerobic tank 1 where microorganism take in a BOD component and releases phosphorus in return. The outflow liquid from the tank 1 flows together with part of the mixed liquid flowing out from a nitrification tank 3 into a denitrification tnak 2. The mixed liquid in the tank 2 is kept stirred, and the microorganisms therein convert the BOD component to an org. carbon source and reduce nitric acid ions and nitrous acid ions to gaseous nitrogen. The mixed liquid flowing out from the tank 2 is conducted into the tank 3 where a rotary disc device 7 as a fixing means for living things with part of the discs held dipped in the water is provided. Ammonia is converted to nitric acid in an aerobic atmosphere in said tank.