Shifts of bacterial community and predictive functional profiling of denitrifying phosphorus removal - Partial nitrification - Anammox three-stage nitrogen and phosphorus removal before and after coupling for treating simulated wastewater with low C/N

The feasibility of simultaneous denitrification phosphorus removal (DPR) partial nitrification (PN) and anammox (AMX) process were investigated in a coupling three-stage sequencing batch reactors (SBR) system for treating municipal sewage. Functional bacteria were pre-cultured and then coupled for low matrix simulated municipal wastewater treatment (50 mgN.L-1, 10 mgP.L-1 and 200 mgCOD.L-1). The total nitrogen (TN) removal efficiency of 79.94%, a phosphorus removal efficiency of 93.62%, and a chemical oxygen demand (COD) removal efficiency of 92.34% were achieved during coupling operation. The periodic experiment results showed that the contributions of anoxic and aerobic phosphorus uptake were 65.52% and 34.48%, respectively. The simultaneous nitrification and denitrification occurred in the PN reactor. Further microbial community illustrated that the coupling operation changed the structure of bacteria in three SBRs. The main functional groups were AOB Nitrosomonas, anammox bacteria Candidatus Brocadia, DPAO Acinetobacter and PAO norank_f_Caldilineaceae in coupling progress. Network-based analyses and functional genes forecast based on KEGG database revealed that the microbial community in each reactor adopted different regulation pathways to improve resistance to system coupling operation. The results of this study provide the basis for understanding the process variations from the pre-culture to coupling operation for three-sludge DPR-PN-AMX municipal wastewater treatment process, which is important to quick start-up and efficient operation of coupling process.

Automated summary

This study investigated the feasibility of simultaneous denitrification phosphorus removal (DPR) partial nitrification (PN) and anammox (AMX) process in a coupling three-stage sequencing batch reactors (SBR) system for treating municipal sewage. The results showed high removal efficiencies for total nitrogen (TN), phosphorus, and chemical oxygen demand (COD). The periodic experiment results revealed the contributions of anoxic and aerobic phosphorus uptake. The microbial community and functional groups were also analyzed during the coupling operation.