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.