METHOD OF BIOLOGICALLY TREATING WASTE WATERS Russian patent published in 1998 - IPC

FIELD: waste water treatment. SUBSTANCE: waste water is continuously treated by activated sludge in air tanks, water-sludge mixture is settled in secondary settlers where purified water is separated from activated sludge and sludge biomass is returned to air tank inlets. Activated sludge or a part of it is additionally subjected to aerobic treatment ensuring endogenous metabolism conditions either on functioning activated sludge or under its starvation conditions. This treatment is effected with activated sludge/running water mixture as continuation of biological treatment process. Treatment time is determined from condition that biochemical oxidation of waste water impurities is completed and activated sludge starvation occurs because of lack of nutrients contained in initial waste water. Starvation conditions are created by varying hydraulics of continuous flow of water-sludge mixture in air tank. EFFECT: provided stability of activated sludge makeup and improved its selection quality. 11 cl, 4 tbl, 4 ex