Batch electrodialysis (ED) desalination, which relies on diluate recirculation to produce a desired product, is often conducted at constant voltage. I showed that constant-voltage operation under-utilizes membrane area because the applied current is much lower than the maximum current achievable early in a batch cycle. I hypothesized that designing a controlled to maximize the average ratio of applied to limiting current during a batch cycle can increase the rate of salt removal from a fixed membrane area. To demonstrate, I designed such a controller and used it to raise the production rate by up to 37%, relative to constant-voltage operation.

I additionally derived and validated an analytical prediction of the batch completion time under this type of operation. Supported by experiments, the prediction indicates that time-variant voltage-control can provide the greatest increase in production rate at high feed-to-product concentration ratios and low flow velocities. This work will assist designers and operators seeking to size, evaluate, and maximize the production performance of new and existing batch ED processes.