Optimization of dilute acid and alkaline peroxide pretreatment to enhance ethanol production from wheat straw

Abstract

Objective: The main purpose of this study was to determine the optimal pretreatment process conditions for wheat straw to maximize the overall ethanol yield. Methods: The effects of pretreatment conditions for dilute acid and alkaline peroxide pretreatment were investigated using Response Surface Methodology (RSM). Co-fermentation with S. cerevisiae and P. stipitis was employed to produce ethanol from pretreated solids. Cellulose and xylan composition of wheat straw, degradability of these compounds, as well as ethanol production, were monitored at different conditions. Results: 0.5% H2SO4 concentration, 15% solid loading, and particle size between 0.75-0.9 mm ( 20 mesh) was predicted to be optimal by RSM for dilute acid pretreatment and experiment performed at that condition resulted in overall ethanol yield of 12.95%. The maximum overall ethanol yield determined for alkaline peroxide pretreatment is 18.23% and can be achieved when the pretreatment were done with 0.875% H2O2 at 35 degrees C for 1 h. Experimental results agreed with the responses. Conclusion: Alkaline peroxide pretreatment of wheat straw was found to be more effective than dilute acid pretreatment for enhancing bioethanol production from wheat straw by co-fermentation.