A high-rate sulfidogenic process based on elemental sulfur reduction: Cost-effectiveness evaluation and microbial community analysis

Abstract Biological sulfur reduction is an attractive technology for the treatment of metal-laden wastewater, but its efficiency and cost have been questioned due to the insolubility of sulfur. In this study, a laboratory-scale sulfur-reducing bioreactor was constructed to investigate the long-term feasibility of high-rate sulfur reduction. Our results show that 316 ± 46 mg S/L sulfide was produced within 3 h, corresponding to a high sulfide production rate of 32 ± 5 mg S/L-h, significantly higher than those reported in sulfate-reducing systems. Sulfur reduction processes can significantly reduce the total operational cost compared to sulfate reduction processes. Moreover, long-term sulfur feeding significantly shaped the microbial communities. The predominance of sulfate-reducing genera (24.1%) diminished continuously during the 110 days of operation, and sulfur reducers such as Geobacter and Clostridium became dominant at the end of experiment. All of these findings suggest that high-rate sulfur reduction processes driven by sulfur reducers can be a cost-effective alternative for metal-laden wastewater treatment.