Leakage circuit characteristics of a bipolar membrane electrodialyzer with 5 BP-A-C units

Abstract

Leakage currents inevitably exist in all liquid channels of the plate-and-frame membrane stacks in bipolar membrane electrodialysis (BMED) systems. These leakage currents decrease the efficiency of the devices, and may even cause undesirable heat that can affect non-metallic components used in the membrane stack. In this study, a laboratory-scale BMED system was set up for treating high ammonium chloride organic wastewater. An electrical circuit model consisting of three hydraulic circuits in the membrane stack was established, and processed by using the simulation software Multisim. The leakage circuit characteristics of the BMED system with 5 BP-A-C units were monitored during the desalination process. The electrical resistances of the ducts/slots were shown to be influenced by solution conductivity and geometry. The voltages, currents, and thermal effects at the ducts/slots presented a symmetrical distribution in the membrane stack, and were affected by their electrical resistances during the desalination process. Measures were proposed to minimize any negative effects to improve the BMED design.