15-22: Biofuel production from an ethanol waste stream released from pretreatment of bagasse of sweet sorghum

Cellulose solvent-and organic solvent-based lignocellulose fractionation (COSLIF) is a promising pretreatment technique. This strategy uses concentrated phosphoric acid as a cellulose solvent to disrupt the recalcitrant lignocellulosic structures.  Ethanol is used to dissolve lignin and precipitate the dissolved cellulose and hemicellulose. Ethanol is also utilized to wash off the phosphoric acid, acetic acid and lignin from the pretreated material. This wash generates a waste stream. While ethanol can be distilled at 173^oF for reuse, we aim to produce higher energy density biofuels from this waste at room temperature. To accomplish this goal, pH of the waste stream was raised to 7.0, which resulted in the precipitation of lignin. The liquid part which mainly contained ethanol was used to cultivate an oleaginous yeast strain. The lignin was gasified to produce syngas. In this presentation, we will present our results on: 1) biomass and lipid productivities from the fermentation process; 2) ethanol utilization by this yeast species; and 3) the yield of syngas from lignin through gasification.