A novel denitrifying phosphorus removal and partial nitrification, anammox (DPR-PNA) process for advanced nutrients...

This study developed a novel DPR-PNA (denitrifying phosphorus removal, partial nitrification and anammox) process for sustaining high-strength wastewater treatment in a modified continuous flow reactor without external carbon source. After 259-days operation, a synchronous highly-efficient total inorganic nitrogen, PO₄^3--P and COD_cr removal efficiencies of 88.5%, 89.5% and 90.1% were obtained, respectively even influent nitrogen loading rate up to 3.2 kg m^-3 d^-1. Batch tests revealed that denitrifying phosphorus accumulating organisms (DPAOs) using NO₃^--N as electron acceptors significantly enriched (74% in total PAOs), which emerged remarkable positive impacts on deep-level nutrient removal as the key limiting factor. Furthermore, the NO₂^--N inhibitory threshold value (∼20.0 mg L^-1) for DPAOs was identified, which demonstrated as an inhibitory component in excessive recycling NO_x^--N. From the molecular biology perspective, Dechloromonas-DPAOs group (18.59%) dominated the excellent dephosphatation performance, while Nitrosomonas-AOB (ammonia oxidizing bacteria) group (16.26%) and Candidatus_Brocadia-AnAOB (anammox bacteria) group (15.12%) were responsible for the desirable nitrogen loss process. Overall, the present work highlighted the novel DPR-PNA process for nutrients removal is a promising alternation for wastewater of high nitrogen but low carbon.