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⁻¹h⁻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 °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. Copyright © 2020 Elsevier Ltd. All rights reserved.