(564b) Simultaneous Enhancement of Solid-Liquid Clarification and Removal/Recovery of Fermentation Inhibitory Compounds From Biomass Slurries

Conversion of a lignocellulosic biomass feedstock into a fermentable sugars-rich stream requires pretreatment and enzymatic hydrolysis. During these steps a complex mixture of solids (lignin, along with residual cellulose and hemicellulose), sugars, and degradation compounds (i.e., furfural, hydroxymethyl furfural [HMF], and organic acids) is often produced. Solid-liquid clarification following enzymatic hydrolysis will help eliminate solids mixing problems in fermentation, allowing for higher initial solids concentrations and higher effective sugars loadings for fermentation. At the same time, removal of fermentation inhibitors (furfural, HMF, poly-phenols, acetic acid, etc.) would allow for improved ethanol production rates and yields. Here we report the use of polyelectrolyte flocculating agents to simultaneously enhance solid-liquid clarification and remove fermentation inhibitory compounds. With the addition of flocculant, the efficiency of the solid-liquid clarification operation can be improved by over 40-fold while also improving the clarity of the sugars-rich stream by over 10-times. Simultaneously, with the appropriate selection of polyelectrolyte chemistry, fermentation inhibitory compounds can be selectively removed without the loss of sugars. Finally, by altering solution conditions (pH and the presence of disrupting salts) furfural, HMF, and/or acetic acid can be recovered as a concentrated and purified by-product.