Ca(II) and Mg(II) significantly enhanced the nitrogen removal capacity of Arthrobacter arilaitensis relative to Zn(II) and Ni(II)

Abstract

This study investigated the impacts of alkaline-earth metals [Ca(II), Mg(II)] and heavy metals [Zn(II), Ni(II)] on the nitrogen removal capacity of Arthrobacter arilaitensis Y-10. StrainY-10 was able to tolerate 20 mg/L Ca(II) and its ammonium removal efficiency was 100%. 0.5 mg/L Ca(II) effectively promoted total nitrogen removal from wastewater containing nitrite. Mg(II) supplementation substantially enhanced the bacterial growth and nitrogen reduction. As Mg(II) concentrations increased from 0 to 2 mg/L, the ammonium, nitrate and nitrite removal efficiencies increased by 40.62%, 69.91% and 64.68%, respectively. Although the nitrogen removal ability of strain Y-10 was sharply hindered by Zn(II) and Ni(II), it occurred continuously even when the Zn(II) concentration reached 30 mg/L. However, the ammonium and total nitrogen removal almost stopped at 8 mg/L Ni(II), and the denitrification capacity was lost when the Ni(II) concentration exceeded 1 mg/L. The results demonstrate that Ca(II) and especially Mg(II) could significantly enhance the nitrogen removal capacity of Arthrobacter arilaitensis relative to Zn(II) and Ni(II).

Keywords: Alkaline-earth metals; Arthrobacter arilaitensis; Heavy metals; Nitrogen bioremediation.