Biogas Production from Mesophilic Anaerobic Digestion to Treat Lignocellulosic Wastes in Mezcal Production

Abstract

Vinasse and bagasse are residues from the production of mezcal, an alcoholic beverage. Treating these wastes is very important to avoid the contamination of water bodies and soils by their discharge into the environment. One of the processes to treat this type of waste is anaerobic digestion. In this study, mesophilic anaerobic digestions were carried out with different organic loads and a retention time of 30 days, where bagasse was thermally pretreated to decrease cellulose crystallization and reduce lignin content, which is highly resistant to chemical, biological, and enzymatic degradation, constituting a barrier for cellulose utilization during the process such as enzymatic hydrolysis and subsequent fermentation. The process carried out with a lower bagasse proportion of 5% resulted in a more significant reduction of COD, SSV, and a methane percentage of 70%, 49%, and 63%, respectively, while maintaining a pH between 6 and 7.5 and an alkalinity of 2,000 mg/L. These results indicate that the process was not inhibited when the content of bagasse was low, reaching the methanogenesis stage in the anaerobic digestion.