Membrane-based processes for xylitol production from oil palm empty fruit bunches hydrolysate fermentation broth

Oil palm empty fruit bunch (OPEFB) is one of the wastes that has high hemicellulose composition and potentially processed into xylitol via biotransformation route. This study explores the effectiveness of ultrafiltration (UF) and nanofiltration (NF) in purifying and concentrating xylitol from OPEFB hydrolysate-fermentation broth. Various UF membranes, including UF1 (MWCO 150 kDa), UF2-Psf (MWCO 20 kDa), and UF2-PVDF (MWCO 50 kDa), were used, along with NF (MWCO 150 Da). Pre-treating the broth before UF was crucial to remove foulants such as microorganisms and macromolecules. While microfiltration (MF) achieved 100% microorganism rejection, its flux declined rapidly, necessitating feed centrifugation before MF. The choice of UF membrane MWCO significantly influenced xylitol retention, with UF2-PSf leading to substantial xylitol loss and UF2-PVDF showed promising results. NF has shown its applicability in concentrating xylitol in the UF permeate as much as 4 times higher, while permeating 90% of the acetic adic in the solution.