A novel sulfur-driven autotrophic denitrification coupled with bio-cathode system for bioelectricity generation and groundwater remediation

Abstract

This study explored the feasibility of treating wastewater using sulfur-driven autotrophic denitrification (SAD) coupled with the bio-cathode of microbial fuel cell (MFC), focusing on simultaneous bioelectricity generation, denitrification, and desulphurization. A maximum output voltage of 360 mV was obtained with a power generation cycle of 25 h when simulated wastewater with 100.0 mg/L of each NO–3 -N and S2–-S was employed as the influent in the SAD-BMFC. Compared with solo SAD or MFC, SAD-BMFC obtained a higher NO–3 -N removal rate (E12 h ¼ 87.7%, E24 h ¼ 100%), and less NO–2 -N accumulation. S2–-S of the influent was almost completely removed, oxidized to S0-S (88.6–90.2 mg/L) and SO24–-S (9.8–11.4 mg/L). The reaction system achieved self-balance of acidity-alkalinity (pH 7.05–7.35). The SAD process was the main pathway for NO–3 -N removal (80.2%) and a smaller proportion of electrons came from the bio-cathode. This study effectively combined SAD with a bio-cathode system for simultaneous energy harvest and bio-enhanced remediation of groundwater contaminated by both NO–3 -N and S2–-S.