TREATING PROCESS OF WASTE WATER

摘要

PURPOSE:To remove phosphorus contained in waste water by a biological treatment efficiently by treating overflow water from an excess sludge concentration tank and/or P-contg. org. waste water from a sludge dehydration stage further with a physicochemical dephosphorization means. CONSTITUTION:Suspended solid in the feed water is removed in the first stage in a settling basin 1, then fed to a aeration tank 2 where it is mixed and allowed to contact with returned sludge. The activated sludge adsorbs org. substances in the fed water and liberates phosphorus compds. The liquid mixture is transferred to an aerobic tank 3 where oxidation of the org. substances and accumulation of phosphorus compds. in the activated sludge are taken place. The solid and liquid in the sludge accumulating a large amt. of phosphorus compds. are separated in a final settling basin 4; a part of the separated solid is transferred to an anaerobic tank 2 as returned sludge and the rest is transferred to a sludge concentrating tank 5 as excess sludge. The overflow water from the concentration tank and the waste water from a dehydrator 6 are treated in an adjusting tank 7 to adjust their pH, then dephosphorized in a physicochemical dephosphorization tank 10, and returned to the initial settling basin 1.