Achieving mainstream nitrogen and phosphorus removal through Simultaneous partial Nitrification, Anammox,...

Simultaneous partial Nitrification, Anammox, and Denitrification (SNAD) is a promising and energy-efficient nitrogen removal process, which is powerless to eliminate phosphorus and confronted the problem of excessive effluent nitrate once applied in municipal sewage treatment characterized with high C/N ratio (≥2). Herein, by coupling SNAD with denitrifying phosphorus removal (DPR) process in a single-tank reactor, a novel integrative process (termed as SNADPR) was designed to treat municipal sewage. The removal efficiencies of TN, PO₄^3--P, and COD under the optimized conditions (T = 30 °C, HRT = 24 h, DO = 0.45 mg/L) were 89.15 ± 2.19%, 92.93 ± 0.60%, and 99.17 ± 1.58%, respectively. Distinctive microbial community distribution was harvested, where anammox bacteria (AnAOB, Candidatus_Kuenenia and Candidatus_Brocadia) were mainly located in biofilm, whereas denitrifying polyphosphate-accumulating organisms (DPAOs, Dechloromonas and Pseudomonas) and ammonium oxidizing bacteria (AOB, Nitrosomonas) basically lived in suspended floc. The SRT separation between biofilm and floc was reached by conserving AnAOB-rich biofilm and termly discharging phosphorus-rich floc.