ACID HEMICELLULOSE HYDROLYSATES - PHYSICAL TREATMENTS AND CONTINUOUS IMMOBILIZED-CELL FERMENTATIONS

Hardwood hemicellulose acid hydrolysates, enriched in pentoses through countercurrent operations, have been fermented by Pachysolen tannophi lus NRRL Y2460 in batch reactors. In order to evaluate the effects of pentose as well as inhibitor concentrations on the overall ethanol yie ld, several materials have been used for the physical treatment of thi s hydrolysate: Fly ash, a mixture of ion-exchange resins, a porous mat erial constituted by SiO2 and Al2O3 and a mixture of organic solvents. The best combination, consisting of an overliming pretreatment follow ed by a secondary treatment in a column filled with the Si-Al material , has assured an increase in ethanol concentration of 15%. Finally, th e data of continuous fermentations of these hydrolysates in an immobil ized-cell reactor are presented and discussed.