Study on the Effectiveness of Sulfate Reducing Bacteria to Remove Heavy Metals (Fe, Mn, Cu, Cr) in Acid Mine Drainage

Abstract

Aiming at the problem of environmental pollution caused by heavy metals such as Fe, Mn, Cu, and Cr, Sulfate Reducing Bacteria (SRB) were enriched in mining soil. SRB was added to AMD containing different concentrations of Fe, Mn, Cu, and Cr by batch experiments to explore the potential of SRB for treating heavy metals in AMD. Testing combining Scanning Electron Microscopy–Energy Dispersive Spectroscopy (SEM-EDS), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) revealed the mechanism by which heavy metal ions were removed by SRB. The results showed that SRB had a strong ability to remove total Fe in the concentration range of 0–300 mg/L, and the removal percentage of total Fe reached to 92.16–93.17%. SRB had a good removal effect on total Cu, in the concentration range of 0–20 mg/L, and the removal percentage of total Cu reached to 79.79–81.80%. SRB had a good removal effect on total Cr as well; SRB activity would probably not be inhibited for total Cr concentrations below 500 mg/L. The ability to solidify different heavy metal ions using SRB was as follows: total Cr > total Fe > total Mn > total Cu. When SRB removed Fe2+ there was precipitation at the same time, appearing as black granules. This precipitation consisted mainly of FeS, and contained small amounts of Fe3(PO4)2-8H2O, FeCO3, Fe(OH)2, Fe(OH)3, and Fe2S as well.