Bioethanol production from dilute acid pretreated Indian bamboo variety (Dendrocalamus sp.) by separate hydrolysis and fermentation

Abstract

Bioethanol from lignocellulosic biomass can be utilized for clean and renewable energy production. Bamboo (BM) was used as a feed stock for the production of bioethanol after dilute acid pretreatment and enzymatic saccharification. In this study different mineral and organic acids were screened to select the best pretreatment agent. Dilute H2SO4 was selected and the effectiveness of pretreatment was evaluated by enzymatic saccharification. Parameters like acid concentration, biomass loading and incubation time were optimized by adopting a Taguchi design. Under optimized pretreatment conditions 0.319 g/g of reducing sugar was produced. The effect of various process parameters affecting enzymatic saccharification like solid loading, enzyme loading, incubation time and surfactant concentration on enzymatic hydrolysis was studied using a response surface method according to Box-Behnken design. Under optimized hydrolysis conditions - 11.25% (w/w) of biomass loading, 50 FPU of commercial cellulase, 0.125% (w/w) of Tween-80 as surfactant and 42 h of incubation, 0.651 g/g of reducing sugar was produced. Physicochemical characterizations of native and dilute acid pretreated BM were carried out by scanning electron microscopy (SEM) and there were morphological differences between the native and pretreated sample. Model validation showed a good agreement between experimental results and the predicted responses. Fermentation of the enzymatic hydrolysed liquid from the pretreated biomass using S. cerevisiae showed bioethanol yield of 1.76% (v/v) with an efficiency of 41.69%.