ABSTRACT
As in every membrane process, electrodialysis (ED) basically results from the interaction of three scientific domains: membranes, energy, and medium; it is characterized by two main parameters, permeability and selectivity. The concentration polarization, as in every membrane process in an electrodialysis unit, also imposes a reduction in the production rate which is directly related to the current density. But, as in the case of any membrane process, the existence of a concentration polarization phenomenon may give rise to some favorable effect. Throughout the diluting and concentrating cells of an electrodialysis stack and in the membranes, electrical conduction is due to ionic transport. Under the forced flow conditions imposed in conventional electrodialysis, relative mixing of the main flowing streams and concentration polarization layers gives an average effect. When the objective of the electrodialysis process is production of potable water or demineralized solution of specified salinity, the most common method of quality and process control is by means of electric sensing equipment.
