A comparison of biological, enzymatic, chemical and hydrothermal pretreatments for producing biomethane from Agave bagasse

Agave bagasse is a lignocellulosic agroindustrial waste suitable for biofuel production. This study aimed to compare biological, enzymatic, chemical, and hydrothermal pretreatments applied to Agave bagasse in terms of solubilization of carbohydrates (CHO) and chemical oxygen demand (COD), as well as the biochemical methane potential (BMP) from hydrolyzates. Most pretreatments behave similarly, with an average yield of 0.16 +/- 0.02 g(COD)/g, only the chemical pretreatment overcame this yield by a factor of 2.6 with a CHO/COD ratio of 0.95. The concentrations of inhibitors - furfural, hydroxymethylfurfural, and phenols - were higher in the chemical hydrolyzates than in the biological and enzymatic hydrolyzates. BMP from most hydrolyzates was the same, on average 219 +/- 15 mL/g(CODin), hydrolyzates differentiate only in terms of lag phase and the methane production rates.