This handbook emphasizes the use of synthetic membranes for separations involving industrial or municipal process streams. Little will be said concerning the use of membranes in medical applications as in artificial kidneys or for controlled drug release. Most of the membrane processes are pressure driven. The notable exception to this is electrodialysis (ED) by which ions are separated under the influence of an electric field. In addition, the chapter on coupled transport covers processes which are driven under the influence of a concentration gradient
