Enrichment denitrifying phosphorus-accumulating organisms in alternating anoxic-anaerobic/aerobic biofilter for advanced nitrogen and phosphorus removal from municipal wastewater

Eutrophication and the degradation of natural water can result from excessive nitrogen and phosphorus in aquatic ecosystems. The denitrifying phosphorus removal (DPR) process shows promise for simultaneous nitrogen and phosphorus removal from municipal wastewater. However, enriching denitrifying phosphorus-accumulating organisms (DPAOs) always in conventional wastewater treatment is a challenging. To enhance the synchronous nitrogen and phosphorus removal efficiency from domestic wastewater, this study employed the alternating anoxic-anaerobic/aerobic biofilter (alternating A-A/O BF) system for DPAOs enrichment. Results showed that DPAOs were successfully enriched after 60 days of operation, where DPAOs contributed 84 % to the overall phosphorus removal. The optimal removal of COD, NH4+-N, TN and PO43−-P was stable at 83.14 %, 99.02 %, 69.75 % and 85.19 %, respectively, when the influent NH4+-N, NO3−-N, PO43−-P and anaerobic COD concentration was in the range of 40 ± 2 mg/L, 15 ± 1 mg/L, 12 ± 1 mg/L and 300 ± 50 mg/L. Microbial community analysis showed that the relative abundance of major DPAOs such as Aeromonas (4.47 %), Hyphomicrobium (0.42 %), Pseudomonas (0.21 %), and Pseudofulvimonas (0.18 %) in the optimum conditions stage increased significantly compared with that in the start-up stage. The results in this study contributes to the understanding of the critical role of DPAOs in the biological nutrient removal (BNR) technology.