Revalorization of Agave Bagasse by Alkaline Organosolv Treatment and the Effect of Delignification on Enzymatic Saccharification and Methane Production

Agave bagasse (AB) is a lignocellulosic biomass with potential to obtain high value-added products such as lignin, microcrystalline cellulose, and polysaccharides that can be used for biofuel production. A Central Composite Design (CCD) was used to evaluate the effect of temperature, thermal treatment time, ethanol concentration, solid/liquid ratio, size particle, and sodium hydroxide concentration on delignification and lignin recovery from AB. In addition, the influence of delignification on the enzymatic hydrolysis using commercial enzymes was determined. This organosolv process allowed a delignification of 91.49% and 76% of the lignin recovery, at 150 degrees C, 10 min, 40% (v/v) ethanol, solid/liquid ratio of 1:10 g/mL, particle size of 0.5 mm - 1 mm, and 5.5% (w/v) sodium hydroxide. The maximum specific yield of enzymatic hydrolysis (SYEH), under the best conditions for delignification, was of 844.40 +/- 9.70 mg total sugars per g of bagasse pretreated with organosolv (BPO), which was 4.42 times higher than the yield obtained from bagasse without pretreatment (BWP). Additionally, the enzymatic hydrolysate of BPO produced 303.62 +/- 10.62 NmLCH4/g BPO. Furthermore, an energy recovery efficiency of 64.13 +/- 0.9% was obtained for BPO hydrolysate which is 2.60 times higher than that of BWP hydrolysate (24.88 +/- 0.92%). In a biorefinery concept, alkaline organosolv pretreatment of AB was highly efficient for lignin production, and improved the enzymatic hydrolysis of polysaccharides, which allowed a higher energy recovery.