Wastewater are presenting a major problem for the environment. Therefore, it is necessary to remove certain contaminats in order to release the water from the system or to reuse it as a process water or potable water, depending on the quality of the feed. It is presented in this work one of the ways to eliminate certain contaminants, membrane operation elctrodialysis. To get a broader picture, other membrane operations of separation such as microfiltration, ultrafiltration, nanofiltration and reverse osmosis are explained in this thesis, as well as basic concepts of wastewater and membranes. Since the reverce osmosis is the major competitor to the electrodialysis, this thesis also talks about advantages and disadvantages of electrodialysis in reference to the reverse osmosis. Process of electrodialysis is explained in detail, starting from the historical background, general description, operating regimes, stack configuration, and continuing with membranes, electrodes, types of electrodialysis regarding to the operating regime and applications of electrodialysis. It is shown how the electrodialysis developed within last 50 years and became competitive to the other methods of separation, not just the ones that use membranes. More research is still necessary in order to optimize the process and also to find other potential applications of electrodialysis.