Characteristics and mechanism of simultaneous nitrate and phenol removal by a newly isolated Cupriavidus oxalaticus T2

Phenol and nitrate in wastewater are harmful to organisms and the environment due to their ecotoxicity. Biological treatment is considered as an environmentally friendly approach for their removal. At present, limited studies explored the capability of single bacterium with simultaneous phenol degradation and aerobic denitrification. In this work, a Cupriavidus oxalaticus T2 with the capability of simultaneous phenol degradation and denitrification under aerobic conditions was isolated from activated sludge. Single factor tests demonstrated that the denitrification optimal conditions of T2 were the carbon source of sodium succinate, C/N ratio of 10, 30 °C, shaking speed of 150 rpm, and pH of 6–7. Strain T2 could remove 100 mg/L NO3−-N within 12 h under optimal conditions without obvious accumulation of NO2−-N and NH4+-N. Moreover, it could simultaneously remove 69 mg/L of NO3−-N and 1000 mg/L of phenol. This study revealed that the strain degraded phenol via ortho-pathway and removed nitrate involved in two pathways: denitrification and dissimilatory nitrate reduction to ammonium. A new strain with the capability of simultaneous nitrate removal and phenol degradation was characterized, suggesting its potential application in further eco-friendly treatment of wastewater. •A novel aerobic denitrifying bacterium Cupriavidus oxalaticus T2 was isolated.•Strain T2 was capable of simultaneous removal of phenol nitrate under aerobic conditions.•Strain T2 could simultaneously remove 650 mg/L phenol and 50 mg/L nitrate within 36 h.•The genome of T2 revealed the pathways of phenol degradation and nitrate reduction.