Bioelectrochemical system-aided sewer gas control: A feasibility study via semi-continuous operation

Bioelectrochemical systems (BES) show promise for controlling methane and sulfide in sewers without chemical additives, yet their performance under different sewer environments remains poorly understood. This study evaluated the effectiveness and underlying mechanisms of BES in newly constructed (NS) and existing (ES) sewer environments. In NS environments, applying an anode potential of −0.2 V (vs Ag/AgCl) decreased methane production by 38.5–44.6 % (mean 41.6 %) compared to open-circuit controls. Methane suppression was likely associated with stimulated electrogenesis, which intensified competition for acetate and/or induced pH reduction. Conversely, sulfide production increased by 57.9–175.8 % (mean 102.4 %), coinciding with the enrichment of electroactive sulfate-reducing bacteria such as Desulfovibrio (4.8–5.6 % vs. 1.8 % in open-circuit controls). Doubling the anode surface area and/or reducing the influent acetate concentration could prevent the undesirable increase in sulfide production and enabled sulfide control (about 73 % reduction) when the pH dropped below 5. In ES environments, the same anode potential induced substantially lower electroactive bacterial activity than in NS environments (∼0.2 mA vs. ∼3.3 mA), resulting in limited mitigation of both methane and sulfide. Further experiments using real domestic wastewater validated the feasibility of BES for methane suppression (32.2–65.3 %, mean 51.4 %) in NS environments, while the pH decrease induced by current generation was insufficient for sulfide control. This study demonstrates the potential of BES for methane mitigation in NS environments, while also revealing the challenges in sulfide control under conditions of limited biodegradable substrates.