Combined process system for the production of bioethanol from sugarcane straw

This work evaluated the conversion of sugarcane straw into a glucose-rich hydrolysate using a combined process system (CPS) which consists of pretreatment, delignification and enzymatic hydrolysis. The sugarcane straw, with 38.1%, 29.2% and 24.2% of cellulose, hemicellulose and lignin respectively, was submitted to a hydrothermal pretreatment and a delignification process in order to increase the cellulose enzymatic hydrolysis. Straw is the residue to be obtained in sugarcane mills without burning the land previously to the harvesting The CPS, with pretreatment at 190 °C, 10 min, showed 95% of hemicellulose solubilization, 78% of lignin removal and 29% of cellulose degradation. The enzymatic hydrolysis of CPS-cellulignins achieved over 60% cellulose conversion. Considering the cellulose content present in the raw sugarcane straw, only 50% was converted into glucose, due to degradation during the CPS and the enzymatic inefficiency in the hydrolysis stage. In addition, the delignification step did not improve the overall cellulose conversion of the sugarcane straw.