Biofuels Production from Organosolv Treated Lignocellulose: Nondetoxified Fermentation and Microbial Community Analysis

Wastewater generation has been a universal problem during the detoxification process of pretreated residue. To break the recalcitrant structure of sugar cane bagasse and minimize wastewater generation, biocompatible triethylene glycol (TEG) solvent was used for pretreatment and enabled the bioethanol and/or biomethane production from nondetoxified sugar cane bagasse (NDSCB). The yield of ethanol from NDSCB was 62.45% (P-I). Compared to the methane production process (P-II), a fast start-up and 2946 mL of methane were obtained from ∼2.50 g of volatile solids NDSCB during the ethanol–methane coproduction process (P-III), while that of P-II is 2618 mL. The material flow indicates that nondetoxified fermentation is suitable for methane production. Moreover, the P-III process changed the distribution of the bacterial and methanogenic communities as Syntrophotalea and Methanobacterium were dominant. The possible reason for the longer lag phase in P-II might stem from the rivalry between Mestoga and acetoclastic methanogens in acetate usage. This study introduces environmentally friendly biofuel processes for the valorization of lignocellulose.