In some industrial processes there are wastes of valuable elements, so it could be very important for the efficiency of the process to recover these elements. Recovery by ion exchange frequently presents the problem of the posterior extraction of the valuable elements by elution from the resin. One interesting solution appears when the eluent may be the raw material of the process that takes with it the product recovered. An example is the recovery of potassium from a fertilizer industrial wastewater at high ionic solution concentration coming from a crystallization process. When this is to be carried out, not only the high efficiency of counter-ion retention is a key factor, but also an adequate evolution of the co-ion component, since both are feed material of the main process. Design and simulation of this process, with low Donnan exclusion, requires a reliable model for the evolution of both counter- and co-ions in column operation of industrial interest, using the basic information of hydrodynamics and ion exchange characteristics. The work presented here shows the good applicability of this recovery coupling process, and the simulation of the column elution operation; a key part of the process. The simulation of the loading step was carried out in previous works. Simulation of some breakthrough curves are presented as example in this article.