The N2O production and mechanism analysis of simultaneous nitrification and denitrification in biofilm reactor

Lab scale SBR (Sequencing Batch Reactor) filled with carbon fibre is used to investigate the N2O production of simultaneous nitrification and denitrification and the mechanism of the N2O production is also discussed. The results show that the efficiency of simultaneous nitrification and denitrification keeps above 79%. When Dissolved Oxygen (DO) is 0.2, 0.4, 1.0, 1.5 mg/L, the N2O production is 0.005, 0.025, 0.021, 0.025 g/g N-removed, respectively, which is lower than the production of short-cut nitrification. In one cycle, the N2O production increases with the oxidation of NH4+-N. When the oxidation of NH4+-N finished, the production of N2O decreases sharply. During aeration, the correlation between the N2O production rate and ρ(COD) concentration is found. After analysis, heterotrophic nitrification and aerobic denitrification are suggested to be the main source of N2O.