Synergistic partial denitrification, anammox and in-situ fermentation (SPDAF) process for treating domestic and nitrate wastewater: Response of nitrogen removal performance to decreasing temperature

A synergistic partial denitrification, anaerobic ammonium oxidation (Anammox), and in-situ fermentation (SPDAF) system was established to solve problems of wastewater treatment plants (WWTPs) in combined treatment of domestic sewage, and nitrate wastewater discharged from industrial areas. The SPDAF system was started up at decreasing temperatures (26.8-18.9 celcius), and remained robust at abrupt temperature drop and drastic temperature fluctuations (20.7-14.1 celcius). The influent and effluent total inorganic nitrogen (TIN) were 97.0 +/- 3.7 mg/L and 10.3 +/- 4.0 mg/L, respectively. In-situ fermentation supplemented electron donors for NO3-N reduction. A high TIN removal efficiency, of 89.5 +/- 3.9% was obtained. Specifically, Anammox contributed 90.9 +/- 5.2% to TIN removal. Furthermore, the abundances of hydrolysis and acidogenesis bacteria were 14.02% and 29.47% in the low and high zones, respectively, which promoted fermentation and the use of complex organics. This study provided novel insights for actual operation of WWTPs.

Automated summary

The study successfully established a SPDAF system for combined treatment of domestic sewage and nitrate wastewater from industrial areas, achieving a high TIN removal efficiency of 89.5%. Anammox played a crucial role in TIN removal, while in-situ fermentation provided electron donors to promote the utilization of complex organics.