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Up-concentration of sugars in pretreated-rice straw by an osmotic pressure-driven method

Shibuya, Masafumi, Yasukawa, Masahiro, Sasaki, Kengo, Tanaka, Yasuhiro, Takahashi, Tomoki, Kondo, Akihiko, Matsuyama, Hideto
Biochemical engineering journal 2017 v.121 pp. 13-16
Saccharomyces cerevisiae, biomass, ethanol, ethanol production, fermentation, lignocellulose, nanofiltration, osmosis, osmotic pressure, rice straw, saccharification, sodium chloride, triethylamine, xylose
Forward osmosis (FO), driven by high osmotic pressure, was used for the first time for bioethanol production from lignocellulosic biomass. A commercial membrane, TFC-ES (Hydration Technology Innovation), was used and 3.6M triethylamine (TEA) was chosen as the draw solution because the concentration ratio against a model xylose solution was similar to that achieved with 2.5M NaCl. The liquid fraction of hot-water-pretreated rice straw was concentrated by using the FO membrane. The initial sugar concentration of 199mM increased to 825 and 1612mM after 48 and 72h of FO concentration, respectively, and these values were much higher than those obtained from nanofiltration. Simultaneous saccharification and fermentation of the liquid fraction after 48h of FO concentration by xylose-fermenting recombinant Saccharomyces cerevisiae produced 17.7g/L of ethanol after 24h fermentation. Thus, the FO process has tremendous potential to up-concentrate sugars obtained from lignocellulosic biomass.