A study on the nitrogen removal efficacy of bacterium Acinetobacter tandoii MZ-5 from a contaminated river of Shenzhen, Guangdong Province, China

Heterotrophic nitrification-aerobic denitrification (HN-AD) has advantages over the traditional nitrogen removal process when removing multiple types of nitrogen in wastewater treatment. Acinetobacter tandoii MZ-5, which is capable of HN-AD, was isolated from the sediment of a polluted river for the first time. It used NH4--N, NO2--N and NO3--N as sole nitrogen sources with maximum removal rates of 2.28, 1.18 and 1.04 mg L(-1)h(-1), respectively. Simultaneous nitrification and denitrification were observed when using mixed N sources and NH4+-N was preferentially utilized. High nitrogen removal efficiencies (> 90%) were achieved under the following conditions: C/N ratio 11-18, pH 6-8, 25-30 degrees C and dissolved oxygen 7.35-7.66 mg L-1. Strain MZ-5 was effective at treating wastewater from landfill leachate treatment plants, with NH4+-N, NO3--N and total nitrogen (TN) removal efficiencies of 99.28%, 44.85% and 45.31%, respectively. Thus, strain MZ-5 may be a good candidate for wastewater treatment.