Patent ID: 7510655
Filing Date: 2009-03-31
Classification: C02F,Y02W,Y10S

Abstract:
1. A process for treating BOD, nitrogen, and phosphorus containing wastewater, the process comprising: providing wastewater influent into an anoxic zone having activated sludge; mixing the wastewater influent with the activated sludge in the anoxic zone to form a first mixed liquor; providing the first mixed liquor into a first of a plurality of further treatment zones; mixing the first mixed liquor with activated sludge in the first of the plurality of further treatment zones to form a second mixed liquor; providing the second mixed liquor into a second of the plurality of further treatment zones; mixing the second mixed liquor with activated sludge in the second of the plurality of further treatment zones to form a third mixed liquor; providing the third mixed liquor into a third of the plurality of further treatment zones; mixing the third mixed liquor with activated sludge in the third of the plurality of further treatment zones to form a fourth mixed liquor; transferring a portion of the fourth mixed liquor from the third of the plurality of further treatment zones to a membrane bioreactor; filtering the fourth mixed liquor to form a filtrate and an activated sludge; and selectively recycling at least a portion of the activated sludge from the membrane bioreactor to at least one of the anoxic zone, the first of the plurality of further treatment zones, and the second of the plurality of further treatment zones.