Improving the fermentability of dilute acid hydrolysate and recovering low-concentration p-toluenesulfonic acid based on a fixed-bed column with hyper-cross-linked resin

Abstract

As the closest pretreatment to industrialization, dilute acid hydrolysis is effective in producing fermentable sugars from lignocellulose. However, the reuse of acid catalysts is a difficult problem that restricts the economy of the biorefining process. In addition, inhibitors generated during dilute acid pretreatment seriously affect the bioconversion of fermentable sugars. In this study, the dynamic adsorption and desorption of dilute acid hydrolysate on a fixed-bed column with hyper-cross-linked resin were investigated to improve the fermentability of hydrolysate by removing inhibitors and recover the low-concentration p-toluenesulfonic acid (p-TsOH) for cyclic pretreatment. The results showed that p-TsOH can be recovered by dynamic adsorption and desorption for cyclic pretreatment, which released similar concentration of xylose compared with the first pretreatment. Moreover, the total sugar loss rate was less than 2 % after adsorption. The fermentability of hydrolysate after adsorption by the fixed-bed column was greatly improved. The fermentation performance of Trichosporon cutaneum (T. cutaneum) was enhanced with a yeast biomass of 19.26 g/L, lipid content of 25.62 %, and lipid yield of 4.93 g/L. Compared with the fermentation results of hydrolysate without detoxification, the lipid content and lipid yield increased by 67.12 % and 94.10 %, respectively. In summary, this study provides a feasible technology for improving the fermentability of dilute acid hydrolysate and recovering acid catalysts.