Patent ID: 7713413
Filing Date: 2010-05-11
Classification: C02F,Y02W,Y10S

Abstract:
1. A process for treating BOD, nitrogen, and phosphorus containing wastewater, the process comprising: providing wastewater influent to an oxygen-deficit aeration zone having activated sludge; maintaining an oxygen deficit throughout the oxygen-deficit aeration zone by controlling a rate of oxygen supplied to the oxygen-deficit aeration zone to less than a rate of oxygen consumption by micro-organisms in the oxygen-deficit aeration zone; mixing the wastewater influent with the activated sludge in the oxygen-deficit aeration zone to form a first mixed liquor; transferring the first mixed liquor from the oxygen-deficit aeration zone to an oxygen-surplus aeration zone; mixing the first mixed liquor with activated sludge in the oxygen-surplus aeration zone to form a second mixed liquor; recycling a portion of the second mixed liquor to the oxygen-deficit aeration zone; transferring a second portion of the second mixed liquor from the oxygen-surplus aeration zone to an anoxic reactor tank; mixing the second portion of the second mixed liquor with activated sludge in the anoxic reactor tank to form a third mixed liquor; transferring a portion of the third mixed liquor from the anoxic reactor tank to a membrane filter; filtering the third mixed liquor to form a filtrate and an activated sludge; and recycling at least a portion of the activated sludge from the membrane filter to the oxygen-deficit aeration zone.