Design and optimization of electrodialysis process parameters for brackish water treatment

Effect of flow velocity and cell-pair thickness in electrodialysis (ED) is studied. The production cost includes pump energy, while the size of the system is considered as an output variable. The performance of ED system depends on three categories of process parameters namely water quality data, stack configuration and flow characteristic inside the stack. The design of ED system is complex due to interrelation among the system variables so the design calculation chronology steps are developed with flow-chart for the fix feed salinity of groundwater and salt removal rate. The effect of recovery ratio on capital and energy cost is studied and found unidirectional. Sparingly soluble salt present in feed decides the upper limit and obtained 70–75% recovery rate based on the feedwater quality. The optimum value of the linear flow velocity and cell-pair thickness can be obtained by the trade-off among capital cost, stack energy cost and pumping energy cost. Simultaneous effect of both the variable on minimizing the total cost gives the narrow working range of flow velocity 15–17 cm/s and 0.4–0.8 mm thickness. The minimum production cost of 0.08 USD/m3 is obtained at 16 cm/s velocity and 0.5 mm thickness.