STEAM PRETREATMENT CONDITIONS FOR EFFECTIVE ENZYMATIC-HYDROLYSIS AND RECOVERY YIELDS OF EUCALYPTUS-VIMINALIS WOOD CHIPS

Wood chips from Eucalyptus viminalis were steam treated over a range of temperatures and residence times in the absence or presence of SO2. When the substrate was steam treated without explosion, the initial moisture content of the chips had a significant influence on the recovery yield and the degree of enzymatic hydrolysis. Pretreatment by steam explosion showed no variation resulting from differences in the initial moisture content of the chips. SO2 catalysis was shown to be particularly beneficial for the steam treatment of green chips. More than 95% of the original cellulose could be hydrolysed to glucose with more than 80% of the original pentosan recovered as xylose in the water soluble fraction. This indicated a need for chips with a high enough moisture content necessary to generate enough sulphurous acid from SO2 to act as an effective catalyst.