Combined ultrafiltration and electrodeionization techniques for microbial xylitol purification

Abstract

Oil palm empty fruit bunch (OPEFB) is biomass waste from crude palm oil industry that can be utilized for xylitol production. In recent years, xylitol production is dominated by a microbial fermentation method where the fermentation product contains many impurities, thus requires further purification and separation processes. In this work, ultrafiltration (UF) and electrodeionization (EDI) membranes were used for purification of xylitol from either model solution or OPEFB hydrolysate that has been fermented by Debaromyces hansenii. First, the optimum conditions for purification of xylitol from xylose, acetic acid, and salts in model solution using EDI were evaluated. The results showed that the optimum current density, concentrate flow rate, and diluate flow rate was found to be 22.5A/m2, 0.4m/s, and 0.5m/s, respectively. Meanwhile, validation experiment using the OPEFB hydrolysate fermentation broth showed that UF-EDI membrane configuration was able to remove 99% of microorganism and biomass, 99% pigment, >46% of xylose, and >99% ionic impurities including >90% acetic acid with a loss of xylitol about 30–50%.