Following the control experiment fermentation was conducted

The concentration of sugars obtained by pre-hydrolysis of wood chips is low and it is not economically feasible to use this medium for microbial fermentation to produce high value products (Qi et al., 2011). A second method combining concentration and detoxification by nanofiltration was added to the procedure to increase the sugar concentration. The LY2409881 hydrolysate thus produced was further detoxified by flocculation. As shown in Table 2, when the NF270 membrane was used in the nanofiltration step, phenols were the only inhibitors affected and their concentration ratio was increased by a factor of 2.97, while it remained practically unchanged for acetic acid, furfural and HMF. Qi et al. (2011) have also observed a negative retention of furfural when using NF270 to concentrate a model solution of xylose, glucose and furfural. After flocculation, the amount of acetic acid decreased by 77.7%, whereas the concentration of HMF and furfural remained high. The detoxification strategy combining pre-hydrolysate concentration and hydrolysate flocculation was effective in concentrating the sugars, but not in removing the inhibitors.