Effects of Fe(II) concentration on the biosynthesis of schwertmannite by Acidithiobacillus ferrooxidans and the As(III) removal capacity of schwertmannite.

The effect of Fe(II) concentrations on schwertmannite bio-synthesis and the As(III) removal capacity of schwertmannite were investigated in this study. Acidithiobalillus ferrooxidans (A. ferrooxidans) were inoculated into five FeSO4 systems with initial concentrations of 50, 100, 200, 300, and 400 mmol/L, respectively, to bio-synthesize schwertmannite. The Fe(II) of the systems were almost completely oxidised at 48, 72, 120, 168, and 192 h, respectively, and the bio-schwertmannite yield was 1.99, 3.81, 9.36, 12.42, and 21.60 g/L. The results of this study indicate that all minerals harvested from the different systems are schwertmannite. As the initial Fe(II) concentration increases, the effect of the minerals removing As(III) decreases; moreover, the structure and extracellular polymeric substance (EPS) of schwertmannite may regulate the As(III) removal process. The EPS generated by the A. ferrooxidans can absorb As(III). The outcomes of this study provide fresh insights into the bio-synthetic regulation of schwertmannite and play a significant role in treating As-containing groundwater.