Simultaneous saccharification and fermentation of microwave/alkali pre-treated rice straw to ethanol.

The simultaneous saccharification and fermentation (SSF) of two different pre-treated rice straws to ethanol were optimised using cellulase from Trichoderma reesei and Saccharomyces cerevisiae YC-097 cells, respectively. The SSF optima for microwave/alkali pre-treated rice straw were 100 g  l −1 substrate, 40 °C, 15 mg [cellulase] g −1 [substrate], initial pH 5·3 and 72 h. Under the above optimum conditions ethanol concentration reached 25·8 g  l −1 and ethanol yield was 57·5%. The SSF optima for rice straw pre-treated by alkali alone were 100 g  l −1 substrate, 40 °C, 20 mg [cellulase] g −1 [substrate], initial pH 5·3 and 96 h. Under these optimum conditions ethanol concentration and ethanol yield were 23·7 g  l −1 and 52·8%, respectively. It was obvious that production of ethanol from microwave/alkali pre-treated rice straw had lower enzyme loading, shorter reaction time, and could achieve higher ethanol concentration and yield than rice straw pre-treated by alkali alone. The microwave/alkali pre-treatment was an efficient pre-treatment method of rice straw for its ethanol production.