Characterisation of Agricultural and Agro-Industrial Residues as Raw Materials for Ethanol Production

Sugarcane bagasse, rice hulls, peanut shells, and cassava stalks are abundant lignocellulosic residues that could be considered as raw materials for ethanol production in tropical countries. The knowledge on the composition of lignocellulosic materials is important for their effective utilisation. In this work, a systematic comparison of the chemical composition of sugarcane bagasse, peanut shells and two sorts of rice hulls and cassava stalks, was performed using analytical acid hydrolysis and HPLC analysis. The highest carbohydrate fraction, w = 641 g kg–1 of the dry matter was detected in bagasse, which also contained the highest amount of xylan (w = 221 g kg–1). Rice hulls obtained from an artisan mill had the highest glucan fraction, w = 497 g kg–1, whereas peanut shells displayed the highest lignin fraction (w = 365 g kg–1). The highest ethanol potential, around 163 L t–1, was estimated for rice hulls and bagasse. However, the potential of bagasse would be higher than that of rice hulls if conversion of xylan fraction to ethanol would be considered.