Substrates removal and growth kinetic characteristics of a heterotrophic nitrifying-aerobic denitrifying bacterium, Acinetobacter harbinensis HITLi7T at 2 °C

In order to investigate the heterotrophic nitrification and aerobic denitrification ability of Acinetobacter harbinensis HITLi7T at 2 °C, both the growth parameters and substrates utilization characteristics were tested and appropriated kinetic models were obtained in this study. Under the initial concentration of 5 mg/L, the maximum NH4+-N and NO3−-N degradation rates were 0.076 mg NH4+-N/L/h and 0.029 mg NO3−-N/L/h, respectively. At the simultaneous presence of 2.5 mg/L NH4+-N and NO3−-N, the maximum nitrate removal rate increased to 0.054 mg NO3−-N/L/h (1.86 folds), while a slight decrease was observed in NH4+-N removal. Two double-substrate models, Contois-Contois (1) for NH4+-N and TOC, Monod-Contois (2) for NO3−-N and TOC matched well with the experimental data. The kinetic parameters were determined as μmax1 = 0.095 h−1, BA1 = 0.012 mg/L, BT1 = 0.784 g TOC/g biomass (R12 = 0.9997), and μmax2 = 0.032 h−1, KN2 = 0.375 mg/L, BT2 = 1.108 g TOC/g biomass (R22 = 0.9731) by multiple regression equation.