Mine tailings remediation via sulfate-reducing bacteria and iron-reducing bacteria: heavy metals immobilization and biological sealing

Abstract

ABSTRACT Recent years have witnessed a steep rise in the use of SRB and IRB for the remediation of heavy metal contamination. This study investigated the effects of SRB and IRB on the physical and chemical properties of copper tailings. Besides, altered microbial community structure during the remediation process and the remediation mechanism were also explored. The results showed that bioremediation using SRB and IRB increased the pH of copper tailing and permeation time, and reduced ORP and the concentration of heavy metals, resulting in a friendly environment. The biological sealing was created from insoluble precipitates secreted by microbes in blocked seepage channels. This biological sealing prevented the infiltration of rain and oxygen and prevented the leaching of heavy metals. These findings have never been reported previously. In the exudates, the bioremediation resulted in the change of the dominant microorganisms from oxidised bacteria to SRB and IRB. In the copper mine tailings, the effect of bioremediation on microbial community varied with the depths of tailings. In addition, the species of microorganisms were also significantly different at different depths of tailings, and the key SRB, including Desulfosporosinus, Desulfotomaculum and Desulfovibrio, mainly existed in the middle and low part of mine tailings.