Patent ID: 6592762
Filing Date: 2003-07-15
Classification: C02F,Y02W,Y10S

Abstract:
A process for treating BOD, nitrogen and phosphorus containing wastewater, the process comprising:introducing wastewater influent into an anaerobic zone having activated sludge; mixing the wastewater influent with the activated sludge in the anaerobic zone to form a mixed liquor; introducing the mixed liquor into an oxygen-deficit aeration zone; recycling denitrified mixed liquor from the oxygen-deficit aeration zone to the anaerobic zone for mixing therein with wastewater; transferring the mixed liquor from the oxygen-deficit aeration zone to an oxygen-surplus aeration zone; transferring a portion of the mixed liquor from the oxygen-surplus aeration zone to a settling zone wherein a supernatant is separated from settled sludge; and recycling at least a portion of the settled sludge to the oxygen-deficit aeration zone as recycled activated sludge.