Sulfate removal from the seawater using single-chamber bioelectrochemical system

The aim of this study was to investigate the feasibility of sulfate removal from seawater using the bioelectrochemical system (BES). A single-chamber BES was constructed with graphite felt as the anode and carbon brush as the cathode. The BES was inoculated with sea mud and tested with seawater containing 2200 ± 200 mg/L SO42− and 2 g/L sodium acetate as the substrate under an applied voltage of 0.8 V. Results showed that 98.5 ± 5.0 % of SO42− in the seawater was efficiently removed in the BES within 132 h. The maximum current density in the BES reached 3.4 ± 0.1 A/m3 with ~100 % acetate utilization. Most of SO42− was reduced to S2− and the final S2− concentration reached 498 ± 25 mg/L in the BES. Organic sulfur compounds were detected in the SO42− reduction. According to bacterial community and reconstruction of unobserved state analyses, the SO42− removal was mainly attributed to the reaction in the cathodic biofilm. The electricity consumption for the SO42− removal was much lower in the BES than in the membrane technology. Our results can provide a promising method to enhance the seawater utilization in the industry.