Due to the problems of low nitrogen removal efficiency and unclear electron transfer during biological denitrification treatment of an oligotrophic drinking water reservoir, the nitrogen removal characteristics, environmental adaptability, and electron transfer during denitrification were systematically studied using the aerobic denitrifier Acinetobacter junii ZMF5, which has efficient nitrogen removal ability. The results showed that:① Strain ZMF5 exhibited efficient heterotrophic nitrification and aerobic denitrification ability, with an ammonia removal rate of 0.211 mg·(L·h)-1 and a nitrate removal rate of 0.236 mg·(L·h)-1, and the nitrification intermediates were not accumulated during the treatment process. ② According to analysis of the nitrogen removal efficiency and growth kinetics of strain ZMF5, the strain can effectively utilize different types of carbon source, and show efficient nitrogen removal efficiency under the conditions of low C/N, low pH, and low temperature. ③ Analysis of nitrogen balance showed that carboxylate compound, compared with carbohydrate, could promote the process of aerobic denitrification and change the nitrogen removal pathway of strain ZMF5, i.e., 38.81% of nitrogen was transformed into gas, higher than the 29.81% for assimilation. ④ Analysis of carbon balance indicated that most carbon sources were used as electron donors in the denitrification process, but fewer electrons were used for nitrate reduction, and with respect to different carbon sources, electron transfer to the nitrate respiratory chain was regulated by different reduction potentials, electron donor abundance, and molecular weight. Acinetobacter junii ZMF5 could be used to control nitrogen pollution in drinking water reservoirs.
Keywords: aerobic denitrification; carbon balance; nitrogen balance; nitrogen removal; oligotrophic drinking water reservoir.