The forward-osmosis (FO) processes have received much attention in past years as an energy saving desalination process. A typical FO process should inclu de a draw solute recovery step which contributes to the main operation costs of the process. Therefore, investigating the energy consumption is very important for the development and employment of the forward osmosis process. In this work, NH3-CO2, Na2SO4, propylene glycol mono-butyl ether, and dipropylamine were selected as draw solutes. The FO processes of different draw solute recovery approaches were simulated by Aspen PlusTM with a customized FO unit model. The electrolyte Non-Random Two-Liquid (Electrolyte-NRTL) and Universal Quasi Chemical (UNIQUAC) models were employed to calculate the thermodynamic properties of the feed and draw solutions. The simulation results indicated that the FO performance decreased under high feed concentration, while the energy consumption was improved at high draw solution concentration. The FO process using Na2SO4 showed the lowest energy consumption, followed by NH3-CO2, and dipropylamine. The propylene glycol mono-butyl ether process exhibited the highest energy consumption due to its low solubility in water. Finally, in order to compare the equivalent work of the FO processes, the thermal energy requirements were converted to electrical work.
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