Anaerobic reductive bio-dissolution of jarosites by Acidithiobacillus ferrooxidans using hydrogen as electron donor.

Jarosites are secondary iron-hydroxyl-sulfate minerals and widely occur in bioleaching, acid mine drainage, and acid sulfate soil environments. Anaerobic reductive dissolution of jarosites is yet to be methodically examined. In this study, we explored the bio-dissolution of jarosites by Acidithiobacillus ferrooxidans (At. ferrooxidans) by using hydrogen in batch experiments. After bio-dissolution by At. ferrooxidans for 22 d, ferrous ion concentrations reached 10.07 mM (biologically produced jarosites), 7.68 mM (potassium jarosite), and 1.45 mM (lead jarosite). Strengthening the dissolved jarosites by decreasing the initial pH (pH < 2.0) or by adding citric acid (1, 5, and 10 mM) was inefficient for bio-dissolution owing to restricted cellular activity. The pathways of bio-dissolution should include direct contact bio-dissolution and indirect bio-dissolution and relate to the solubility of jarosites in a bio-dissolution system. The results demonstrate that anaerobic reductive bio-dissolution of jarosites by At. ferrooxidans using hydrogen shows potential. This study also provides opportunities to contribute to the development of the bioleaching field via the aerobic/anaerobic cycle using a single strain to control and reuse jarosites in situ.