Implementation of a Sulfide–Air Fuel Cell Coupled to a Sulfate-Reducing Biocathode for Elemental Sulfur Recovery

Bio-electrochemical systems (BES) are a flexible biotechnological platform that can be employed to treat several types of wastewaters and recover valuable products concomitantly. Sulfate-rich wastewaters usually lack an electron donor; for this reason, implementing BES to treat the sulfate and the possibility of recovering the elemental sulfur (S(0)) offers a solution to this kind of wastewater. This study proposes a novel BES configuration that combines bio-electrochemical sulfate reduction in a biocathode with a sulfide–air fuel cell (FC) to recover S(0). The proposed system achieved high elemental sulfur production rates (up to 386 mg S(0)-S L(−1) d(−1)) with 65% of the sulfate removed recovered as S(0) and a 12% lower energy consumption per kg of S(0) produced (16.50 ± 0.19 kWh kg(−1) S(0)-S) than a conventional electrochemical S(0) recovery system.