Water Treatment Capacity of Forward-Osmosis SystemsUtilizing Power-Plant WasteHeat.

Forwardosmosis (FO) has the potential to improve the energy efficiencyof membrane-based water treatment by leveraging waste heat from steamelectric power generation as the primary driving force for separation.In this study, we develop a comprehensive FO process model, consistingof membrane separation, heat recovery, and draw-solute regeneration(DSR) models. We quantitatively characterize three alternative processesfor DSR: distillation, steam stripping, and air stripping. We thenconstruct a mathematical model of the distillation process for DSRthat incorporates hydrodynamics, mass- and heat-transport resistances,and reaction kinetics, and we integrate this into a model for thefull FO process. Finally, we utilize this FO process model to derivea first-order approximation of the water production capacity giventhe rejected-heat quantity and quality available at U.S. electricpower facilities. We find that the upper bound of FO water treatmentcapacity using low-grade heat sources at electric power facilitiesexceeds process water treatment demand for boiler water makeup andflue-gas-desulfurization wastewater systems. [ABSTRACT FROM AUTHOR]