METHOD OF EXHAUSTING DISSOLVED OXYGEN IN A NITROGEN REMOVAL WASTEWATER TREATMENT PROCESS

摘要

The present invention relates to a nitrogen removal wastewater treatment process and system that entails an anoxic treatment zone followed by an oxic treatment zone with internal recycle of mixed liquor from the oxic treatment zone to the preceding anoxic treatment zone. Prior to recycling the nitrified mixed liquor back into the anoxic zone, the mixed liquor is held within a dissolved oxygen exhauster tank for a selected period of time where the dissolved oxygen concentration of the nitrified mixed liquor is substantially reduced to preferably below 0.5 ppm.