Characterization of biogas and effluent produced during the anaerobic digestion of mezcal vinasse

The production of mezcal generates vinasse, a liquid waste with high concentrations of organic matter and acidic pH, which represents a potential source of pollution. The use of anaerobic biodigesters has emerged as an alternative for the treatment of this waste stream. This study characterizes the anaerobic digestion (AD) of mezcal vinasse in a 10 m³ tubular (bag-type) anaerobic biodigester. To this end, daily biogas production was measured and normalized to standard conditions. The methane content in the produced biogas was determined through carbon dioxide (CO₂) removal, and the thermal efficiency of a biogas stove was evaluated. The physicochemical properties of the liquid effluent resulting from the AD process were also assessed. The results demonstrated that the AD treatment of vinasse with an initial Chemical Oxygen Demand (COD) concentration of 44.93 g L⁻¹ yielded 15.61 L of biogas per liter of vinasse, with a methane concentration of 68.48%. Furthermore, the thermal efficiency of the biogas stove was 35.45%. The effluent obtained had a pH of 7.5 and a COD concentration of 17.00 g L⁻¹, which represents a 62.16% COD removal relative to the influent. Additionally, its organic carbon content reached 17%, while total nitrogen accounted for 19%. These results indicate a high potential for the proposed approach to be implemented as a strategy for waste valorization method, pollution mitigation, local clean energy production, and agroecological applications.