Abstract: The design of a liquid membrane system for the liquid surfactant membrane seperation and concentration of K+ for use in practice is presented. First, a suitable method of design is selected, the form of the apparatus used in this method being changed in a proper way. Then, the facilitated and the active transports of K+ are investigated. We predict:(1)the presence of NaCl in KCl will cause an increase in the flow of K+;(2) this Cl- present may be one source of energy necessary for the active transport of K+;(3)the flow of K+ will be further increased if the Cl- present is replaced by Br- or I-. The experimental results are consistent with the predictions. Finally, a concrete design is suggested.