METHOD AND PLANT FOR BIOCHEMICAL PURIFICATION OF WASTE WATER CONTAINING FERROUS AND ALUMINIUM IONS Russian patent published in 1997 - IPC

FIELD: waste water purification. SUBSTANCE: method involves stages of water preaeration, clarification, and treatment with activated sludge followed by separation of cleaned water. The first two stages are combined with additionally introduced stage of chemical purification of water from ferrous and aluminium ions using addition of alkali reagent to pH 7.0-7.5 in presence of ferrous ion oxidation catalyst and treatment with coagulant. As oxidation catalyst, salts of higher oxygen acids of nonmetals or VI and VII group metals are used in quantity 0.01-0.02% based on oxidized ions weight. As coagulant, activated sludge in quantity 3-5 g/l is utilized. After clarification stage, stream of clarified waste water under continuous aeration is passed through integrated biofilter-air tank containing activated sludge in immobilized and suspended state. Treatment plant includes preaerator in assembly with primary thin-layer settler and integrated biofilter-air tank in assembly with secondary thin-layer settler, and additional preaerator and pressure container with control valve on bottom discharge. Case of biofilter-air tank additionally encloses screening funnel with outer diameter of bell equal to inner diameter of air tank case. EFFECT: enlarged purification range. 4 cl, 1 dwg, 2 tbl