Fractionation of sugarcane bagasse using hydrothermal and advanced oxidative pretreatments for bioethanol and biogas production in lignocellulose biorefineries

The fractionation of sugarcane bagasse (SB) by hydrothermal pretreatment (HP, autohydrolysis) followed by alkaline extraction (AE) and advanced oxidative pretreatment (AOP) for production of second-generation ethanol and biogas was investigated. The AOP of SB was optimized using a Doehlert design, varying the applied H2O2 load, liquid-to-solid ratio (LSR), and time. The responses evaluated were yield (Y), residual cellulose (RC), delignification (DE), and enzymatic conversion (EC). The AE of SB pretreated by HP led to 61.8% DE (using 0.2 mol L-1 NaOH). This high lignin removal enabled substantial savings of H2O2 in the AOP. The optimized AOP conditions led to 78% Y, 82.2% RC, 42.7% DE, and 88.9% EC (overall glucose yield of 60.9%). Fermentation of the enzymatic hydrolysate with Saccharomyces cerevisiae yielded 190.8 L-ethanol ton(S)(B)(-1). Biogas production by anaerobic digestion of residual liquid streams of the pretreatment steps yielded 27.46 NLCH4 kgs(SB)(-1). An energy balance was estimated for the SB fractionation.