Comparing Sugar Titers and Ethanol Yields from Fed Batch Fermentation of Celf and DA Pretreated Poplar Solids at High Glucan Loadings

Biological conversion of lignocellulosic biomass to liquid fuels reduces greenhouse gas emissions and addresses other economic and strategic challenges. However, costs are high due to high enzyme loadings and capital costs, particularly at glucan loadings over 10% needed to realize economically attractive ethanol concentrations. Because solids concentrations above about 10% cannot be readily mixed in batch fermentations, a fed-batch strategy was applied to establish maximum carbohydrate conversions from enzymatic hydrolysis of THF Co-Solvent Enhanced Lignocellulosic Fractionation (CELF) and dilute acid pretreated poplar wood. At 15, 18 and 20% glucan loadings, glucose concentrations of 63, 70, and 75g/l were achieved in only 2 days from CELF pretreated solids while concentrations from hydrolysis of dilute acid solids were only 45, 53, and 60g/l, respectively.