Characterization and anaerobic digestion of highly concentrated Mexican wine by-products and effluents

Wine production has increased in recent years, especially in developing countries such as Mexico. This increase is followed by an increase of winery effluents that must be treated to avoid environmental risks. However, little information is available about the characteristics of these effluents and the possible treatments. This paper aimed to characterize the effluents and by-products generated by the Mexican winery industry and to evaluate the performance and stability of the anaerobic treatment using a single-stage and a two-stage process. Results showed that the winery effluents had a high content of biodegradable organic matter, with chemical oxygen demand (COD) values ranging from 221 to 436 g COD/L. The single-stage anaerobic process was able to treat an organic loading rate of 9.6 kg COD/(m³ d); however, it was unstable and highly dependent on the addition of bicarbonate alkalinity (0.31 g NaHCO₃/g COD removed). The two-stage process was more stable working at a higher organic load (12.1 kg COD/(m³ d)) and was less dependent on the addition of bicarbonate (0.17 g NaHCO₃/g COD removed). The results highlight the potential of the winery effluents to produce methane through anaerobic digestion in a two-stage process, making wine production more sustainable.