Hydrodynamic Cavitation-Assisted Oxidative Pretreatment and Sequential Production of Ethanol and Xylitol as Innovative Approaches for Sugarcane Bagasse Biorefineries

In the present work, a new alternative of hydrodynamic cavitation-assisted pretreatment associated with an advanced oxidative process was proposed, together with a new approach to obtain bioproducts in sequential fermentations. Enzymatic hydrolysate of sugarcane bagasse (SCB) was fermented to ethanol by Saccharomyces cerevisiae. After distillation of this alcohol, the obtained vinasse was used to produce xylitol by Candida tropicalis. Influent variables in pretreatment were evaluated by performing experiments according to a statistical design, and, at optimum conditions (ozone flowrate of 10 mg/min, and H2O2 concentration of 0.61%), about 84% and 78% of glucan and xylan hydrolysis yields were obtained in enzymatic hydrolysis, respectively. In the sequential fermentations for ethanol and xylitol production, yield values of 0.41 g/g and 0.55 g/g, respectively, were obtained, with corresponding volumetric productivities of 8.33 g/Lh and 0.64 g/Lh, respectively. The proposed strategy was shown as a promising approach for biorefineries, considering the mild conditions of pretreatment and the possibility of high ethanol production using S. cerevisiae in a fermentation process similar to that one already available in sucro-alcoholic sector, followed by xylitol production in vinasse-based medium.