Electrically driven membrane processes, and electrodialysis in particular, are important unit operations, especially within the field of desalination - making tab water from sea water. Electrically driven membrane processes will be introduced. Important terms such as critical current density, desalination degree, and current efficiency will be described through illustrations and a large amount of examples. Thus, you will be familiar with the basic principles and theory within this important field on a bachelor or master of science level.