Evaluation of Steam Explosion Pretreatment and Enzymatic Hydrolysis Conditions for Agave Bagasse in Biomethane Production

Abstract

The production of biofuels from lignocellulosic biomass includes a pretreatment step to alter the biomass structure and facilitate the enzymatic degradation of the polymers to obtain assimilable compounds. In this study, agave bagasse (AB) was used as a feedstock for obtaining methane, for which AB was pretreated with steam explosion and enzymatically hydrolyzed. The pretreatment conditions corresponded to severity factors (SFs) within a range from 1.65 to 2.89, while enzymatic hydrolysis was performed with enzyme loads of Cellic CTec2 within a range from 0.12 to 3.6 mgprotein g−1AB. The best global yields (including pretreatment and enzymatic hydrolysis) of total carbohydrates (TCs), glucose (GLU), xylose (XYL), and chemical oxygen demand (COD) were 0.7 g TC g−1AB, 0.12 g GLU g−1AB, 0.03 g XYL g−1AB, and 0.20 g O2 g−1AB obtained using 2.4 mgprotein g−1AB of Cellic CTec2 with agave bagasse pretreated with an SF of 2.41. The contribution of pretreatment to the global TC yield ranged from 13 to 34% for the different systems evaluated. The biochemical potential of methane (BMP) of hydrolysates (pretreatment at SF 2.41 and 2.4 mgprotein g−1AB of Cellic CTec2) was 0.284 ± 0.02 in NL CH4 g−1 COD with a COD removal of 78.4 ± 1.3. This BMP value was 40% higher than the BMP obtained in the system without enzymatic hydrolysis, indicating the impact of this step on conversion to biomethane. The results at the BMP level indicated the potential of this residue for biofuel production.