| Traditional nitrogen and phosphorus removal processes can't get perfect removal effect because of the conflict on sludge ages, and competition for organic substrate, nitrate among organisms in the processes. Continuous flow anaerobic/anoxic/nitrifying biofilm (A2N) process makes nitrifying bacteria grow in biofilm and denitrifying bacteria and phosphorus accumulating bacteria in activated sludge and achieves denitrifying phosphorus removal with the same organic carbon resource to overcome the problems faced by the traditional nitrogen and phosphorus removal processes. It was expected that it could be a new way for municipal wastewater treatment for nitrogen and phosphorus removal with low C/N rate.The start-up and performance of continuous flow A2N process was investigated in this paper and the effects of influent characteristics on the A2N process were studied. Moreover, batch test was carried out. The comparation between the effects of phosphorus removal of Anaerobic/aerobic SBR and Anaerobic/anoxic/aerobic SBR with the A2N was also discussed. The results show:1. The effects of phosphorus release in the anaerobic stage and its uptake in the anoxic stage in the system were not good when the activated sludge got from Dengjiacun sewage plant with A2/O process applied was directly innoculated in the continuous anaerobic/anoxic way. It indicated that denitrifying phosphate-accumulating bacteria could not be cultivated in this way.2. With low loads, good COD, TN and PO43--P removal were achieved. Removal efficiencies of COD, TN and PO43--P were 96%, 80% and 99% while COD loads, NH4+-N loads and PO43--P loads were 0.857-0.943kg/(m3·d), 0.016-0.018kg/(m3·d) and 0.121-0.170kg/(m3·d), respectively. When COD loads, NH4+-N loads and PO43--P loads were 1.817-1.971kg/(m3·d), 0.032-0.034kg/(m3·d) and 0.251-0.299kg/(m3·d), COD, TN and PO43--P removal efficiencies were 90%, 72% and 70%, respectively. When COD loads, NH4+-N loads and PO43--P loads were 0.840-1.366kg/(m3·d), 0.025-0.029kg/(m3·d) and 0.161-0.190kg/(m3 ·d), COD, TN and PO43--P removal efficiencies reached 92%, 77% and 80%, respectively.3. It cost about 10 days for the activated sludge from the Dengjiacun WWTP to achieve phosphorus removal rate of 99% under A/O performance in a SBR. Excellent phosphorus removal efficiency could not be obtained when Anaerobic/aerobic SBR was directly operated in the way of Anaerobic/anoxic/aerobic SBR and nitrate was added at one time at the beginning of the anoxic stage.4. The sludge with denitrifying phosphorus removal in the system had good settle ability. Its SVI was between 59.83 and 97.13mL/g; Bacteria in the activated sludge contained more phosphorus than ordinary activated sludge; PHB and poly-phosphate granules could be observed.
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