Optimizing of operation parameters in EDI process by orthogonal test method

In recent years, electrode ionization technology has been widely used for ultrapure water production. The effects of major operational parameters such as feed hardness, dilute flux and stack voltage on dilute product resistivity and scaling extend were investigated through an orthogonal experiment(L₉(3)⁴). The factorial results of Design-Expert software revealed that the interaction of dilute flux and stack voltage influenced the dilute product resistivity most significantly, while the single factor of stack voltage was the main influencing factor on the scaling index (SI), which was proposed to quantify the scaling extend. It was found that dilute product resistivity maximization (16.38 MΩ·cm) and scaling index minimization can be achieved when feed hardness, dilute flux and stack voltage were 3.9 mg/L (as CaCO₃), 21 L/h and 14V, respectively, which can be used for designing and operating a large scale process.