Highly efficient and robust treatment of low C/N actual domestic sewage via integrated fermentation, partial-nitrification, partial-denitrification and anammox (IFPNDA).

For achieving efficient and robust treatment of domestic sewage with C/N around 2.8, this study innovatively developed an integrated fermentation, partial-nitrification, partial-denitrification and anammox (IFPNDA) process based on the Anaerobic Baffled Reactor and Continuous-flow Stirred Tank Reactor (ABR-CSTR) bioreactor. Desirable N-removal efficiency of 87.5 ± 2.1% was obtained without external organics, correspondingly effluent total nitrogen (TN) concentration reached 6.1 ± 0.7 mg/L. The N-removal stability was greatly facilitated by the effective linkage between partial nitrification (PN) process and partial denitrification (PD) process in emergency. Highly enriched hydrolytic bacteria (6.9%) and acidogenic bacteria (5.7%) in A1, especially Comamonas (2.8%) and Longilinea (3.5%), induced the significant increase of volatile fatty acids (VFAs) in domestic sewage. Thauera (6.1%) in A2 and Nitrosomonas (5.4%) in A3 acted as the dominant flora of nitrite supplies for anammox in IFPNDA process. Candidatus_Brocadia (2.4%) dominated the advanced nitrogen removal. The IFPNDA process exhibited much potential for achieving energy neutrality during wastewater treatment.