BACKGROUNDSingle-stage nitrogen removal using anammox and partial nitrification process (SNAP process) is a promising process to treat low C/N wastewater relying on ammonia-oxidizing bacteria (AOB) and anaerobic ammonium oxidation (anammox) bacteria. However, excess nitrate (NO3-) in effluent is a common problem for the SNAP process. The denitrifying phosphorus removal (DPAO) process using NO3- as electron acceptor was adopted to reduce nitrate in effluent from the SNAP process, while phosphorus removal was also achieved simultaneously. Thus, a novel combined process (DPAO-SNAP process) was established to achieve nitrogen and phosphorus removal simultaneously. RESULTSThe DPAO-SNAP process achieved average 95.7% chemical oxygen demand, 98.2% total nitrogen and 97.8% total phosphorus removal efficiencies during stable stages. Furthermore, Candidatus Kuenenia and Nitrosomonas were identified as the dominant genus for anammox bacteria and AOB, respectively. Defluviicoccus was enriched as the glycogen-accumulating microorganism (GAOs) for the DPAO process with acetate as the carbon source, while Rhodocyclales was the dominant genus in the DPAO process with mixed carbon source. CONCLUSIONThis DPAO-SNAP process could not only resolve the problem of effluent NO3- in the SNAP process but also simultaneously achieved high removal efficiency of COD, TN and TP with a low need for carbon sources (COD/N/P=25:15:1). (c) 2017 Society of Chemical Industry