Forward osmosis system analysis for optimum design and operating conditions

Abstract

Low energy consumption and less fouling propensity of forward osmosis (FO) processes have been attractive as a promising water filtration technology. The performance of this process is however significantly influenced by its operating conditions. Moreover, these operating parameters have both favourable and adverse effects on its performance. Therefore, it is very important to optimize its performance for efficient and economic operation. This study aims to develop a software to analyze a full-scale FO system for optimum performance. A comprehensive theoretical framework was developed to estimate the performance of FO system. Analysis results were compared with the experimental results to validate the models. About 5% deviation of simulation results and the experimental findings shows a very good agreement between them. A novel optimization algorithm was then developed to estimate the minimum required draw solution (DS) inlet flowrate and the number of elements in a pressure vessel to attain the design objectives (i.e. desired final DS concentration and recovery rate at a specific feed solution (FS) flowrate). A detailed parametric study was also conducted to determine the optimum operating conditions for different objectives. It showed that for a specific design objective, higher recovery rate can be achieved by increasing the DS flowrate and number of elements in a pressure vessel. In contrast, lower final concentration can be obtained by lowering the DS flowrate and increasing the number of elements. Finally, a MATLAB based software with graphical user interface was developed to make the analysis process easier and efficient.