Ethanol Production from Microwave-Assisted FeCl3 Pretreated Rice Straw Using Free and Immobilized Cells of <i>Trichoderma viride</i> and <i>Sacharomyces cerevisiae</i>

Abstract

Microwave-assisted ferric chloride (FeCl3) pretreated rice straw was utilized for reducing sugars production and ethanol production with free and immobilized cells of Trichoderma viride and Sacharomyces cerevisiae. The maximum reducing sugars concentration (3.46 g/L) and YR/r (reducing sugars yield/rice straw consumption; 0.17 g/g) from pretreated rice straw with free cells of Trichoderma viride at 84&nbsp;h were much higher than those from untreated rice straw (1.24 g/L, 0.06 g/g). Untreated and pretreated rice straw was converted to ethanol by free cells of Trichoderma viride and Sacharomyces cerevisiae. The maximum ethanol concentration from pretreated rice straw was 2.14 g/L representing the YE/r (ethanol yield/rice straw consumption) of 0.11 g/g, which was higher than those from untreated rice straw (1.13 g/L, 0.06 g/g). Pretreated rice straw was used to produce ethanol by free cells of Trichoderma viride and immobilized Sacharomyces cerevisiae, and by co-immobilized cells of Trichoderma viride and Sacharomyces cerevisiae. The maximum ethanol concentration obtained by co-immobilized Trichoderma viride and Sacharomyces cerevisiae was 2.75 g/L with the YE/r of 0.14 g/g at 84&nbsp;h, which was higher than those achieved by free cells of Trichoderma viride and immobilized Sacharomyces cerevisiae (2.36 g/L, 0.12 g/g). Co-immobilized Trichoderma viride and Sacharomyces cerevisiae were reused five times in repeated batch experiments. The ethanol concentration and the YE/r in each batch were above 2.75 g/L and 0.14 g/g after 84&nbsp;h, respectively. This proved the vitality and stability of co-immobilized Trichoderma viride and Sacharomyces cerevisiae.