Cultivation and start-up of A2N denitrifying phosphorus and nitrogen removal system

As A₂N is two-sludge system, by using the method that first bringing up the cultivation of denitrifying phosphorus removing bacteria (DPB) and nitrification biofilm separately then connecting them, which can start up A₂N system successfully, nitrification biofilm was cultivated in a sequencing batch reactor (SBR), the activated sludge used is from the sedimentation tank, after 30 days, NH₄⁺-N effluent concentration steadily stayed below 0.5 mg·L^-1. In another SBR the activated sludge for The enrichment of DPB is from the anaerobic tank, the sludge was firstly operated under anaerobic/aerobic (A/O) condition after 20 days, PAOs was successfully enriched. Then , the activated sludge was conducted under anaerobic/anoxic/aerobic (A/A/O) condition, maintaining the anaerobic time, gradually increased anoxic time and induced aerobic time ,after 30 days DPB was successfully enriched, two phases totally take 50 days. The treatment effect of A₂N system was gradually steady after a period of 30days .The removal efficiency of total nitrogen and phosphorus are above 85% and 95%, so A₂N system is started up successfully.