The role of sulphate-reducing bacteria (SRB) in bioremediation of sulphate-rich wastewater: focus on the source of electron donors

The industrial activity has increased with the world’s population in urban and non-urban environments. Sulphate (SO42-) is commonly found in aquatic ecosystems and is generally non-toxic to aquatic life, unless present in very high concentrations in an environment affected by human activities. Nowadays, there has been growing interest in the bioremediation of SO42- wastewater as a sustainable and a viable method with the advantages of employing microorganism. This paper provides an overview of the sulfur biogeochemical cycle, microbiology of sulphate-reducing bacteria (SRB), their application in treating SO42- laden wastewater, the crucial factors influencing SO42- removal efficiency, and more importantly, explores the potential for sulfur and metal recovery from mining and industrial waste, along with the source of electron donors. Previous studies in this field have shown that the removal of SO42- and other pollutants is affected by the wastewater matrix chemistry, such as temperature, pH, SO42- and sulfide concentration, ionic strength, nutrients concentration, moisture, redox condition, and the bioavailability of toxic metal ions. Apart from these results, more than 90% of potentially toxic elements (PTEs) and SO42- can be removed by the desired bacteria. Although bioremediation has disadvantages, it remains a viable method for removing PTEs and anions such as SO42- from SO42--rich wastewater. In the future, the application of SRB in combination with other organic compounds as electron donors and adsorbents is suggested as an effective solution for SO42- bioremediation, and sulfur and metals recovery.