Enhanced performance and kinetics of marine anammox bacteria (MAB) treating nitrogen-rich saline wastewater with Mn(II) and Ni(II) addition

A sequencing batch reactor (SBR) was used to study nitrogen removal performance of marine anammox bacteria (MAB) with Mn(II) and Ni(II) addition. The reactor was operated at 25 +/- 0.5 degrees C with influent pH of 7.5 +/- 0.1. Optimal ammonium removal efficiencies (AREs) were 93.95% and 93.18% with 0.05 mM Mn(II) and 0.025 mM Ni(II), respectively. Both Mn(II) and Ni(II) played key roles in treating nitrogen-rich saline wastewater. However, the effect resulting from Ni(II) was far stronger than Mn(II). With optimal Ni(II) addition (0.025 mM), maximal nitrogen removal rate (NRR) and specific anammox activity (SAA) increased by 14.64% and 57.88%, respectively. Modified Boltzmann model was appropriate to describe nitrogen removal at low Mn(II) and Ni(II) concentrations while remodified Logistic model could be used at high Mn(II) and Ni(II) concentrations. Mn(II) and Ni(II) dosage should be controlled within 0.075 mM to achieve good nitrogen removal in nitrogen-rich saline wastewater treatment.