Effect of NO2--N/NH4+-N and COD/NH4+-N on anaerobic ammonia oxidation coupled denitrification nitrogen and carbon removal

The Sequencing Batch Reactor-Anaerobic Sequencing Batch Reactor (SBR-ASBR) combined process was used to treat actual domestic sewage with low C/N ratio at normal temperature, the partial nitritation was achieved by regulating SBR hypoxia: aerobic time was 80min: 60min, 120min: 60min and 150min: 60min respectively. Then the effluent was pumped into the ASBR reactor, investigate the effect of different influent NO2--N/NH4+-N and COD/ NH4+-N on removal of nitrogen and carbon by anaerobic ammonia oxidation coupled denitrification, and response surface methodology was used to design orthogonal batch test. The results showed that: NO2--N/NH4+-N was 1.55 and COD/NH4+-N was 4.22, the effluent concentrations of NH4+-N, NO2--N and COD were 2.79, 0.47 and 38.37mg/L respectively, and their removal rates were as high as 87.56%, 98.45% and 62.69% respectively. ΔNO2--N/ΔNH4+-N was 2.23, the quantity of generated NO3--N was smaller than the theoretical value by 2.47mg/L, nitrogen was removed by the joint action of anammox and denitrifying, the nitrogen and carbon removal performance of the system was best. When NO2--N/NH4+-N and COD/NH4+-N increased from 0.84 to 1.55 and 3.24 to 4.22, respectively, the contribution of anammox and heterotrophic denitrification to nitrogen removal decreased from 80.40% to 53.33% and 19.60% increased to 46.67%. NO2--N/NH4+-N and COD/NH4+-N had significant interactive effects on the removal of TN and COD, and both showed a positive correlation, R2 were 0.9243 and 0.9700 respectively. © 2021, Editorial Board of China Environmental Science. All right reserved.