Abstract: A heterotrophic nitrification-aerobic denitrification strain ZH7 was isolated from aquaculture pond sediment. The strain ZH7 was identified asAcinetobactersp. by morphological observations, physiological and biochemical assays and 16S rDNA sequencing. The impact of various factors (carbon source, C/N ratio, temperature, pH, shaking speed, NaCl concentration) on the strain’s growth and denitrification performance was investigated. And the heterotrophic nitrification and aerobic denitrification performance of the strain in single nitrogen source and mixed nitrogen source under the optimal conditions was also investigated. The results showed that the strain ZH7 could use sodium acetate as a carbon source, and achieved removal rates of ammonium nitrogen (NH+4-N) and nitrate nitrogen (NO－3-N) exceeding 95% under conditions of C/N of 12－16, temperature of 30 ℃, shaking speed of 180 r/min and pH value of 7－9. In mixed nitrogen source conditions (ammonium and nitrate nitrogen), the strain preferentially utilized ammonium nitrogen. The nitrogen removal process followed the Compertz model, with the maximum removal rate for ammonia nitrogen significantly higher than that for nitrate nitrogen and nitrite nitrogen, withRmof 12.61, 7.17 and 7.23 mg/(L·h), respectively. The strain ZH7 demonstrated the efficient denitrification capabilities and can be considered a potential candidate for biological denitrification.

Key words: Acinetbacter, heterotrophic nitrification, aerobic denitrification, biological nitrogen removal, nitrogenous wastewater