Sugarcane Vinasse and Glycerol as Potential Carbon Sources for Sulfate-Rich Wastewater Treatment: Mitigating the Impacts of Acid Mine Drainage

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High Resolution Image Download MS PowerPoint Slide This study investigated the anaerobic co-digestion of sugarcane vinasse (SV) and glycerol (GOH) as potential carbon sources for treating a sulfate-rich and acidic wastewater (pH 4.0–5.4). The sulfidogenic bioreactor operation was divided into six phases, varying carbon sources and COD/SO 4 2 – (chemical oxygen demand/sulfate) ratios. In Phases I–III, SV was the sole carbon source (COD/SO 4 2 – = 1.6–1.2). Phase IV employed co-digestion of SV and GOH, while Phases V and VI used GOH alone, with metals added in Phase VI to simulate acid mine drainage. The highest sulfate reduction (99%) was achieved under co-digestion of SV and GOH for a COD/SO 4 2 – ratio of 1.4, demonstrating that co-substrate addition can markedly enhance sulfidogenesis. Sulfate reduction was coupled with significant bicarbonate alkalinity generation (>900 mg of CaCO 3 L –1 ) which stabilized the effluent pH near neutrality (5.3–7.4). In contrast, metal toxicity in Phase VI reduced the biomass performance, highlighting the importance of gradual microbial acclimation under inhibitory conditions. Desulfovibrio (5.3%) dominated among sulfate-reducing bacteria, while fermentative genera such as Zymophilus (24.8%), Clostridium (13.0%), and Bacteroides (11.5%) played key syntrophic roles in sustaining sulfidogenesis. Acetate accumulation was associated with pH shifts and incomplete microbial oxidation during later operational stages. Overall, the results demonstrate that co-digestion of SV and GOH is a sustainable and efficient strategy for simultaneous sulfate removal, alkalinity generation, and metal immobilization, providing a promising alternative for the treatment of acid mine drainage and sulfate-rich wastewaters.

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