Evaluation on suitability of osmotic dewatering through forward osmosis (FO) for xylose concentration

Abstract

Forward osmosis (FO) has great potential for sustainable osmotic dewatering, which can attain several goals including low energy use, high water recovery, and low membrane fouling. However, this technology still involves critical issues that should be explored to achieve successful functioning of osmotic dehydration process, such as feed characteristics, FO membrane performance, and draw solution selection. In this study, the effectiveness of FO for osmotic dehydration was demonstrated by adopting xylose solution as model feed. Aside from current energy intensive evaporation methods, this widely used sweetener needs an advanced and energy-efficient concentration method such as FO. The stable performance showed xylose can be sustainably concentrated with a consistently high dewatering rate, whereas the recovery rate using a pressure-driven membrane system was constrained by the bursting pressure of nanofiltration membrane. Lastly, high-quality of concentrated product can be obtained by selecting a suitable draw solution of which its reversely diffused salts barely affect the xylose solution or are used to enhance the xylose quality. Employing Poly (aspartic acid) sodium salt or sugar-based solutes as draw help to preserve the purity of enriched xylose. These results suggest that FO can provide a feasible solution for food processing which requires product concentration through dewatering while preserving and improving its quality.