The performance of nitrogen and phosphorus removal in a pilot-scale anoxic-anaerobic oxidation ditch (OD) process was investigated. In order to achieve a high removal efficiency of nitrogen and phosphorus, the aeration was optimized and an anoxic zone was formed in the front of OD reactor, thus the operation condition was changed to anoxic/anaerobic/anoxic/aerobic. Denitrification and DPR was occurred in the formed anoxic zone, while SND was occurred in the back of the OD reactor, and energy costs were reduced as DO in the OD reactor was relatively low.

No abstract