Pretreatment of wheat straw using steam, steam/acetic acid and steam/ethanol and its enzymatic hydrolysis for sugar production

Wheat straw is a suitable raw material for ethanol production, since it has a high cellulose content. In the bioconversion of lignocellulosic materials to ethanol, pretreatment of the material prior to enzymatic hydrolysis is essential to obtain high overall yields of sugar and ethanol. The objective here is to find additives which increase the efficiency of the sugar production. The pretreatment of wheat straw by steam explosion soaked with acetic acid or ethanol prior to the pretreatment was investigated by varying the temperature (180–225) °C and the retention time (3–60 min). The results showed that the pretreatment of wheat straw by steam explosion with soaked with acetic acid or ethanol was more effective than that by steam explosion alone. Additionally, the pretreatment of wheat straw by steam explosion at 210 °C and 10 min, by steam/acetic acid at 220 °C and 8 min and by steam/ethanol at 220 °C and 5 min resulted in the best overall yield of reducing sugar which was found to be 177.3 g kg−1 on dry solids (DS) basis, 244.1 g kg−1 DS, and 264.3 g kg−1 DS, respectively.