SEWAGE BIOLOGICAL PURIFICATION METHOD Russian patent published in 1996 - IPC

FIELD: purification of municipal and industrial sewage by sewage purification works, that has aerotanks and secondary settlers. SUBSTANCE: method of sewage biological purification provides for sewage with active sludge aeration in aerotank with following its separation or settling out in first stage of secondary settler for 40 - 45 minutes and circulating active sludge return from it into aerotank; clarification of purified water from suspension by settling it out in second stage of secondary settler for 75 - 8 minutes with removal from it excessive active sludge for treatment and elimination. Method allows to increase aerotank operational productivity due to decrease of sludge presence in secondary settlers duration, that is to be returned into aerotank, to increase metabolic activity of sludge and to decrease required volume of aerotank for 15 - 20 %. EFFECT: increased productivity of aerotanks, decreased duration of purification and required volume of aerotanks. 2 cl, 1 dwg, 1 tbl