(479b) Fractionation of Pre-Treatment Hydrolysis Products from Lignocellulosic Biomass

The commercial attractiveness of the enzymatic lignocellulosic based biorefinery for making transportation fuels relies on many factors, including the production of valuable byproducts; minimizing chemical consummables; and efficient water recovery and reuse. If the pre-treatment hydrolysis of woody or herbaceous feedstocks is done with acid and base in a novel sequential reactor design, one of the two final liquid effluents contains a variety of lignin species, alkalinity, and dissolved cellulose?similar to the black liquor produced in the pulp and paper industry. We will describe results from a two-step fractionation approach, pressure-driven ultrafiltration (UF) followed by electrodialysis (ED), with a focus on the ED step and the projected energy efficiency and material balance. The combined processes were run as batch separations. The overall process configuration indicates that >95% of the Klason lignin is recovered in the two streams (UF and ED retentate) and > 78% of the alkalinity can be recovered as NaOH for recycle back to the pre-treatment hydrolysis operation. The remaining Na+ is likely bound to the lignin recovered in the UF retentate. The presentation will focus on the influence of current density and ion exchange membranes' chemistry (all commercially available) on the overall mass fractionation balance and energy efficiency of the ED process.