Xylitol, a natural sugar alcohol with many commercial applications in the food and pharmaceutical industries, has been recognized by the U.S. Department of Energy as a key platform molecule for sustainable production from lignocellulosic biomass. Although current industrial production relies primarily on thermochemical methods, developing a novel biological pathway could offer a more cost-effective and environmentally sustainable alternative. The objective of this work is to use the open-source software BioSTEAM to model the scale-up of an experimentally-developed biological production pathway for xylitol. To model the fermentation of xylose to xylitol, the NREL ethanol fermentation method from Oliveira et al. (1999) was adapted using xylitol-based kinetic models from Mohamad et al. (2016). Using an initial xylose concentration of 10 g/L and a working volume of 200 mL, simulated concentration profiles were created using a WLS regression in order to fit the respective kinetic constants based on experimental data. Separation of xylitol using ion-exchange chromatography was modeled with an adsorption column unit that was modified to include multi-wash regeneration logic and Langmuir isotherm kinetics. Furthermore, the batch crystallizer unit was modified to facilitate crystallization with the initial seed of xylitol crystals. In addition to these adapted processes, units for solids centrifugation, mixing, and evaporating were also incorporated into the process design. BioSTEAM was used to determine the minimum product selling price of xylitol produced using this novel pathway, and was compared to current xylitol market values.
