Characterization of a halophilic heterotrophic nitrification–aerobic denitrification bacterium and its application on treatment of saline wastewater

• Halophilic Vibrio diabolicus SF16 was isolated from marine sediment.
• It had good heterotrophic nitrifying–aerobic denitrifying ability at high salinity.
• It could utilize ammonium to generate primarily inert N2 rather than N2O.
• Strain SF16 improved nitrogen removal efficiency in the biological reactor system.

A novel halophilic bacterium capable of heterotrophic nitrification–aerobic denitrification was isolated from marine sediments and identified as Vibrio diabolicus SF16. It had ability to remove 91.82% of NH4+-N (119.77 mg/L) and 99.71% of NO3−-N (136.43 mg/L). The nitrogen balance showed that 35.83% of initial NH4+-N (119.77 mg/L) was changed to intracellular nitrogen, and 53.98% of the initial NH4+-N was converted to gaseous denitrification products. The existence of napA gene further proved the aerobic denitrification ability of strain SF16. The optimum culture conditions were salinity 1–5%, sodium acetate as carbon source, C/N 10, and pH 7.5–9.5. When an aerated biological filter system inoculated with strain SF16 was employed to treat saline wastewater, the average removal efficiency of NH4+-N and TN reached 97.14% and 73.92%, respectively, indicating great potential of strain SF16 for future full-scale applications.