PROCESS FOR REDUCING NITROUS OXIDE EMISSION FROM WASTE WATER TREATMENT

摘要

An activated sludge process for reducing the amount of N2O released to the atmosphere during biological oxidation of NH3, includes the steps of: mixing wastewater influent (18) containing NH3 and BOD with activated sludge (20) to provide a mixed liquor in a first enclosed aerobic treatment zone (ZONE A) wherein an oxygen containing gas (8) is introduced, the first enclosed aerobic treatment zone having two or more stages (28) in which oxygen is transferred to the liquid phase and BOD is metabolized and NH3 is oxidized to NOx and N2O, transferring the mixed liquor and gas to a second enclosed treatment zone (ZONE B) having two or more stages (26) wherein NOx and N2O are reduced to N2 and an effluent gas (29) is released to the atmosphere; transferring the mixed liquor to a settling zone (14) wherein the activated sludge (15) is separated from the mixed liquor to form a dense sludge and a clear supernatant (22); and returning a portion of the dense sludge to the enclosed first aerobic treatment zone.