The hydrolysis and equilibrium of an iminodiacetic ion exchange resin has been successfully applied to an industrial-waste water with significant quantities of iron and base metals, including copper and cobalt.1,2 Equations based on the mass action law can be used to adequately meet global and individual retentions. When compared with batch tests, the results in fixed-bed load experiments show that kinetic and flow controls must be studied and considered in practice. Experiments of elution in column have also been performed with homogeneous or stratified distribution of the loaded resin as well as with constant and increasing concentrations of eluants. Elution results are highly dependent on the load method, and the results could be improved by employing a fluidized bed or mixing tank contactor during the load step.