Effect of Torrefaction Prior to Biomass Size Reduction on Ethanol Production

Biomass size reduction is a key operation in the process of ethanol production from lignocellulosic materials, since enzymatic saccharification of carbohydrate polymers occurs at the molecular level. Torrefaction technique has been used widely in increasing energy density, hydrophobicity, grindability, enhancing pore structure and reducing the cost of transportation. The aim of this study was to employ torrefaction prior to size reduction of sugarcane bagasse (SB) and waste jute caddies (WJC) and also to investigate its effect on biomass structure, glucose and ethanol yields. The torrefaction experiments of SB and WJC were performed at temperatures of 160, 180, 200 and 220 degrees C and residence times of 20, 40, and 60 min. The crystallinity and chemical nature of biomass materials were analyzed by XRD and FTIR. The pore structure was also examined for pretreated and untreated samples. The sugarcane bagasse pretreated at 200 degrees C for 20 min and waste jute caddies pretreated at 180 degrees C for 40 min were observed to produce highest glucose yields of 199.62 and 234.77 mg g(-1), respectively after saccharification. Furthermore, these pretreated SB and WJC under anaerobic fermentation with supplementation of cysteine hydrochloride were noticed to produce ethanol yields of 81.85 and 95.08 mg g(-1), respectively. Also, these ethanol yields represent 19.34% increase for SB and 20.28% increase for WJC when compared with ethanol yields of untreated biomass fermented under anaerobic conditions with cysteine hydrochloride supplement. The study demonstrates the possibility of incorporating torrefaction before size reduction in bioethanol production process. In addition, cysteine hydrochloride supplementation enhances ethanol yields through anaerobic fermentation.