Liquid hydrolysate of dilute acid-pretreated rice straw was
applied to NTR-729HF, NTR-7250, and ESNA3 (Table 3). The pH
(4.9) of the liquid hydrolysate remained essentially unchanged
after membrane-concentration and was optimal for subsequent
fermentation by S. cerevisiae. A pressure of
1.5 MPa was sufficient to concentrate the sugars through NTR-
7250 and ESNA3; however, 2.0 MPa was required for NTR-729HF.
The permeation rates of the rice straw liquid hydrolysate were
similar (16.6–29.0 kg m–2 h–1) for all three membranes (Table 3).
The liquid hydrolysate was concentrated about twofold (2.07,2.05, and 2.06 times for NTR-729HF, NTR-7250, and ESNA3, respectively)
with glucose and xylose concentrations of 1.99 and 2.25
times, 1.71 and 1.83 times, and 1.85 and 2.09 times after passage
through NTR-729HF, NTR-7250, and ESNA3 membranes, respectively.
These results showed that these three membranes can
separate water and concentrate sugars from liquid hydrolysate.