Partial denitrification in domestic sewage and nitrate wastewater: study of the initiation, influencing factors and operational performance

BACKGROUND: Practical application of the anaerobic ammonium oxidation (anammox) process has been limited by the difficulty of obtaining a stable supply of NO2--N. In this study, partial denitrification was utilized as a novel approach to obtain nitrite for anammox, investigating the initiation, influencing factors and performance of partial denitrification in the simultaneous treatment of domestic sewage and nitrate wastewater. RESULTS: When the influent concentration of NO3--N was 40 mg L-1 and the chemical oxygen demand to nitrate (COD/NO3- -N) ratio was 2.7, the NO2--N accumulation rate exceeded 80%, with an effluent NO2--N concentration of 35.64 mg L-1. Furthermore, the partial denitrification performance was good. When the volume ratio of domestic sewage and nitrate wastewater was adjusted to 2:3 and sodium acetate was added to form a COD/NO3--N ratio of 3.6, the effluent NO2--N/NH4+-N ratio was 1.24 and the effluent NO2--N concentration and average NO2--N accumulation rate reached > 31.24 mg L-1 and 83.38%, respectively, effectively ensuring influent requirements for anammox. CONCLUSION: The NO3--N reduction rate, NO3--N removal rate and NO2--N accumulation rate were positively correlated with the influent nitrate concentration when ranging between 15 and 40 mg L-1. An appropriate increase in the influent COD/NO3-N ratio was conducive to a reduction in the time required for maximum levels of NO2--N accumulation to occur, with an influent NO3--N concentration of 40 mg L-1. The partial denitrification system could simultaneously treat domestic sewage and nitrate wastewater, effectively ensuring that the generated effluent met the influent requirements for subsequent anammox. (c) 2023 Society of Chemical Industry.