abstract
Concentrating sugars using membrane separation, followed by ethanol fermentation by recombinant
xylose-assimilating Saccharomyces cerevisiae, is an attractive technology. Three nanofiltration membranes
(NTR-729HF, NTR-7250, and ESNA3) were effective in concentrating glucose, fructose, and sucrose
from dilute molasses solution and no permeation of sucrose. The separation factors of acetate, formate,
furfural, and 5-hydroxymethyl furfural, which were produced by dilute acid pretreatment of rice straw,
over glucose after passage through these three membranes were 3.37–11.22, 4.71–20.27, 4.32–16.45, and
4.05–16.84, respectively, at pH 5.0, an applied pressure of 1.5 or 2.0 MPa, and 25 C. The separation factors
of these fermentation inhibitors over xylose were infinite, as there was no permeation of xylose. Ethanol
production from approximately two-times concentrated liquid hydrolysate using recombinant
S. cerevisiae was double (5.34–6.44 g L–1) that compared with fermentation of liquid hydrolysate before
membrane separation (2.75 g L–1).