Applications of biological sulfate reduction for remediation of arsenic

The application of biological sulfate reduction technologies have an excellent potential for removing arsenic from groundwater, acid mine drainage, and sediments, among other matrices. Under sulfate reducing conditions, arsenic can be removed from waters by precipitating as an orpiment-like phase (As2S3), a realgar-like phase (AsS) or an arsenopyrite-like phase (FeAsS). Alternatively, it can be removed by adsorption onto a biogenic mackinawite-like phase (FeS), greigite-like phase (Fe3S4) and pyrite-like phase (FeS2) in the presence of iron. There has been a recent interest for studies exploring sulfate reducing conditions for arsenic removal given its numerous advantages over other technologies; however, we found that these studies have not been independently reviewed with emphasis on process fundamentals and their relationship to the performance in applications for arsenic removal. This review paper presents a summary of 32 research studies on the treatment of arsenic using sulfate reducing bacteria (SRB). Overall, these studies have generally focused on treatment of groundwater (13 in total), acid mine drainage (8 in total), and various other matrices (11 in total) with the majority of experimental work typically being conducted in laboratory-based bioreactors including batch reactors and continuous flow reactors. This paper presents an assessment of these study applications in various fields; a background on arsenic tolerant SRBs; discussion on carbon sources used to promote growth and metabolism of SRBs; fundamentals of SRB metabolism; factors impacting bioremediation including arsenic concentrations, heavy metals, hydrogen sulfide, pH, and volatilization; and challenges that remain for successful arsenic bioremediation in the future. (C) 2019 Elsevier Ltd. All rights reserved.