Electrodialysis Simulation to Achieve Optimum Current Density

Electrodialysis is used to remove salts from waste or other water streams, to yield a concentrated brine and a substantially deionized product water. During the electrodialysis process, the boundary layer adjacent to the ion selective membrane can become depleted of ions, resulting in severe pH changes sometimes accompanied by precipitation, and power losses, by a process known as “water-splitting.” In order to optimize the applied electric current density, to achieve maximum deionization without exceeding the limiting current at any point along the path, a simulation program has been created to plot ion concentrations and fluxes, and cell current densities and voltages, along the electrodialysis path. A means for tapering the current density along the path is recommended.