Bioethanol Production from Hydrothermally Pretreated and Delignified Corn Stover by Fed-Batch Simultaneous Saccharification and Fermentation

Bioethanol was manufactured from corn stover after consecutive stages of hydrothermal pretreatment (to solubilize hemicelluloses) and delignification. Hydrothermal pretreatment was carried out by heating aqueous suspensions of corn stover up to reach 180-200 degrees C, and the resulting solids were delignified with ethanol-water solutions (containing 30-70 wt % of ethanol) at 180-200 degrees C. The chemical processing was optimized using the Response Surface Methodology. Delignified solids were employed as substrates for fed-batch Simultaneous Saccharification and Fermentation (SSF) under selected conditions (liquid to solid ratio = 4 g/g, enzyme to substrate ratio = 10 FPU/g substrate). The maximum ethanol concentration (67.5 g ethanol/L, corresponding to 89.1% glucan conversion into ethanol) was obtained using samples pretreated hydrothermally at 180 degrees C and delignified at 200 degrees C in a medium containing 30 wt % ethanol.