Rivers in northern Chile are enriched in arsenic (As) derived from natural and anthropogenic sources. Mining activity in the area, enhances the generation of Acid Mine Drainage (AMD),promoting the mobilization of As from the solid phase. AMD poses a threat to waterways due to low pH, high contents of toxic metals and dissolved salts. Sulfate Reducing Bacteria (SRB) can be used for biological treatment of the contaminated waters, because SRB allow the reduction of sulfate that precipitate metals and metalloids (i.e. As) as insoluble sulfides. Therefore, bioremediation systems based on SRB could be used to remove As from acidic waters indirectly. This study was conducted to determine the presence of sulfate reduction processes under acidic conditions and their potential for As removal from AMD waters. Batch reactors were inoculated with SRB enriched from anaerobic acid sediments. Our results show that As concentrations in aqueous phase were attenuated (> 70%) due to stabilization processes in Fe-rich sediments. In addition, microbiological analysis confirmed the presence of SRB. Thus, processes of sulfate reduction mediated by acid-tolerant SRB can achieve neutralization of pH and a significant As removal from AMD waters, and would be useful in the development of more effective AMD remediation systems.
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