Simultaneous Removal of Ammonium and Cr(VI) by the Newly Isolated Marine Bacterium Sulfitobacter dubius PT04 in Tannery Wastewater.

Biological ammonium nitrogen removal in tannery wastewater is significantly hindered by hexavalent chromium (Cr(VI)) and high salinity. In this study, Sulfitobacter dubius PT04, a newly isolated, salt-tolerant marine bacterium from deep-sea hydrothermal vent sediment in the South Atlantic Ocean, was characterized for its ability to simultaneously remove total ammonia nitrogen (TAN) and Cr(VI). This strain demonstrated effective removal across a pH range of 6-8, temperatures of 25-35 °C, and salinity levels of 0-6%.Optimal conditions identified using Response Surface Methodology (RSM) were pH 6.92, 27.69 °C, and 3.78% salinity. Most TAN was assimilated into biological nitrogen, effectively reducing inorganic nitrogen pollutants. Additionally, Cr(VI) removal was facilitated by enzymatic reactions with reduction activity predominantly in the cell membrane, followed by extracellular release of Cr(III) with minimal surface adsorption. After 7 days of treatment, strain PT04 achieved removal rates of 90.66% for TAN and 74.81% for Cr(VI), highlighting its bioremediation potential for TAN and Cr(VI) in tannery wastewater.