Enhanced anaerobic treatment of sulfate-rich wastewater by electrical voltage application.

Treatment of sulfate-rich wastewater with high methane recovery is a major concern due to sulfide inhibition. Here, an electrical voltage (EV) aims to enhance methanogenesis and sulfidogenesis to treat sulfate-rich wastewater. Two (control and EV-applied) reactors were operated with a gradual decrease in chemical oxygen demand (COD)/SO42- ratios (CSR). EV-applied reactor (EVR) demonstrated an increase of ∼30% in methane production and ∼40% in sulfate removal, compared to the control till CSR of 2.0. At CSR 1.0, the control failed, while EVR still exhibited a stable performance of 50% COD-methane recovery. Microbial community results showed that the relative abundance of sulfate-reducing bacteria in EVR was 1.5 times higher than the control. Furthermore, higher relative abundance of dissimilatory sulfate reductase (>50%) and Ni/Fe hydrogenase (x15) genes demonstrated an improved tolerance against H2S toxicity. This study highlights the importance of EV application by minimizing the byproduct inhibition in sulfate-rich wastewater.