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Water Treatment Capacity of Forward-Osmosis Systems Utilizing Power-Plant Waste Heat
- Zhou, Xingshi, Gingerich, Daniel
B., Mauter, Meagan S.
- Industrial & Engineering Chemistry Research 2015 v.54 no.24 pp. 6378-6389
- air, distillation, electric power, energy efficiency, engineering, heat recovery, hydrodynamics, mathematical models, osmosis, power generation, reaction kinetics, steam, wastewater, water treatment, United States
- Forward osmosis (FO) has the potential to improve the energy efficiency of membrane-based water treatment by leveraging waste heat from steam electric power generation as the primary driving force for separation. In this study, we develop a comprehensive FO process model, consisting of membrane separation, heat recovery, and draw-solute regeneration (DSR) models. We quantitatively characterize three alternative processes for DSR: distillation, steam stripping, and air stripping. We then construct a mathematical model of the distillation process for DSR that incorporates hydrodynamics, mass- and heat-transport resistances, and reaction kinetics, and we integrate this into a model for the full FO process. Finally, we utilize this FO process model to derive a first-order approximation of the water production capacity given the rejected-heat quantity and quality available at U.S. electric power facilities. We find that the upper bound of FO water treatment capacity using low-grade heat sources at electric power facilities exceeds process water treatment demand for boiler water makeup and flue-gas-desulfurization wastewater systems.