Optimisation of simultaneous saccharification and fermentation of wheat straw for ethanol production

With the goal of obtaining a high ethanol yield, wheat straw (WS) was pretreated with a 1.0% (w/w) NaOH solution. Further parameters, including temperature, enzyme loading, yeast concentration and pH that would affect the ethanol yield through simultaneous saccharification and fermentation (SSF), were optimised by means of Box-Behnken design (BBD), a response surface methodology (RSM). All of the experiments were carried out with an initial solid content of 16.0% (w/v) and fermentation time of 120 h. A well fitted regression equation with an R2 value of 0.9603 was obtained. The predicted maximum response value (ethanol yield) was 69.49% under the optimised conditions for SSF: temperature of 37.5 °C, enzyme loading of 30 FPU/g substrate, yeast concentration of 10 g/L and pH of 4.6. The validation experimental result showed that the maximum ethanol yield was 70.76%, which was in accordance with the predicted value.