Characterization of nitrous oxide emissions from a thermophilic denitrifying bacterium Chelatococcus daeguensis TAD1 in an aerated sequencing batch reactor

•N2O emission by the thermophilic aerobic bacterium TAD1 was investigated.•Both C/N ratio and pH had significantly influence N2O emission by strain TAD1.•C/N ratio and pH had interactions on N2O emission and nitrogen removal.•TAD1 emitted little N2O with high nitrogen removal under optimum conditions.

This study was conducted to investigate the nitrogen removal efficiency and N2O emission characteristics of a novel thermophilic aerobic denitrifying bacterium, Chelatococcus daeguensis TAD1, under different C/N ratios and pH values in a batch reactor. Nitrogen removal efficiency and N2O emissions were dramatically influenced by C/N ratio and pH. Moreover, multifactor analysis of variance suggested that these two factors also had significant interaction effects on N2O emissions. The optimum C/N ratio was determined to be 8 (where pH was set to 7), at which a very high nitrogen removal efficiency (>99%) was achieved. Under these conditions, N2O emissions were only 34.43 μg/L and the N2O emission factor was 0.046%, which could offer a promising new microbial resource for N removal and reduction of greenhouse gas emissions during wastewater treatment.