[First sequencing then connecting cultivation of the organisms and fast start-up of A2N two-sludge system].

Using domestic sewage, the cultivation of denitrifying phosphorus removing bacteria (DPB) and start-up of A2N two-sludge system were investigated in a laboratory. The A2N system started up fast by using the method that first bringing up DPB and nitrification biofilm separately then connecting them in the A2N system. The enrichment of DPB used activated sludge from the sedimentation tank of a wastewater treatment plant that working about phosphorus removal. In a sequencing batch reactor (SBR), the sludge mixture was operated under anaerobic-aerobic (A/O) condition firstly. Then, the activated sludge was conducted under anaerobic-anoxic (A/A) condition. During the experiment period of 32 d, DPB was successfully enriched. At the same time, utilizing the activated sludge that enriched of nitrifying bacteria, nitrification biofilm was grown up in another SBR. After 30 d, the average ammonia removal efficiency steadily stayed above 99%. Later, using the nitrification biofilm and the activated sludge that enriched of DPB, the A2 N system was connected for dealing with domestic sewage. After 11 d, the treatment effect of A2 N system attained steady. The total nitrogen and phosphorus concentration of effluent are 0, the nitrate concentration is 10.26 mg/L, and COD is 19.56 mg/L. The removal efficiency of COD, ammonia, total nitrogen and phosphorus are 91%, 100%, 77% and 100%, respectively. Each result shows that the A2N system is started up successfully.