Improvement of bioethanol production from waste chestnut shells via evaluation of mass balance-based pretreatment and glucose recovery process

Abstract

Chestnut shells (CSs), an organic waste generated from food processing, have the potential to be useful feedstock for biorefinery. In this study, to improve the availability of bioresource, KOH pretreatment of CSs was statistically optimized by response surface methodology. Optimal conditions based on the model of biomass to glucose conversion (BtGC) were derived with a CSs loading of 92.7 g/L for 2.5 h at 38.6 °C. In the predictions and experiments, BtGC was 15.3% and 15.7%, respectively, about 2.5-fold improvement compared to the control group (6.3%). In addition, to achieve maximum enzymatic digestibility, effective enzyme loading was investigated. Finally, CSs hydrolysate was utilized as a medium for Saccharomyces cerevisiae K35 and had no inhibitory effect during fermentation. In conclusion, bioethanol production was estimated to be 150 g according to the mass balance based on 1,000 g CSs. This research provides a useful direction for the development of a sustainable society through the valorization of food waste as a resource for biofuel production. • Chestnut Shells (CSs), food processing residue, can be usefully applied as a resource for biorefinery. • The goal of maximizing CSs to glucose conversion (BtGC) was successfully achieved. • The CS pretreatment was performed at a relatively low temperature (38.6 °C). • BtGC was improved 4.7-fold by pretreatment optimization and saccharification profiling. • The bioethanol yield was estimated to be 150 g/kg-CS under the designed processes.