Effective hydrothermal-enzymatic sequential process of agave bagasse enhances saccharification and methane production

Abstract

The efficiency of enzymatic saccharification of lignocellulosic biomass is a key step for biofuels production in the biochemical biorefineries. A novel sequential process, hydrothermal pretreatment followed by enzymatic hydrolysis, of agave bagasse was investigated to improve the release of sugars and the methane production. After optimization of the hydrothermal pretreatment by surface response methodology, a hemicellulose removal of 93.6% was obtained at 180 °C/50 min. Hemicellulose removal enhanced cellulose depolymerization during the enzymatic hydrolysis of the pretreated bagasse by 2.3 times as compared to the untreated bagasse. The single-stage batch methane production of the hydrothermal and enzymatic hydrolysates were 0.223 ± 0.02 NL CH4/ g CODadd and 0.305 ± 0.03 NL CH4/g CODadd respectively, indicating a higher biodegradability of the enzymatic hydrolysate. The combined energy recovered from the hydrothermal and enzymatic hydrolysates was 3.4 times greater than that recovered from untreated agave bagasse hydrolysate. Also, the combined energy recovery was higher than the energy recovery reported in the literature for agave bagasse pretreated with other chemical and hydrothermal pretreatments. Overall, this study enhanced the saccharification efficiency and biodegradability of polysaccharides present in agave bagasse through efficient saccharification of cellulose and hemicellulose. This was reflected in a high value of combined energy recovery efficiency (54.1%) in the form of methane.