The effect of influential factors on separation of monovalent (Na+), divalent (Cu2+, Zn2+, Pb2+) and trivalent (Cr3+) ions from wastewater was investigated using AMV and CMV ion-exchange membranes. Taguchi experimental design was used to plan a minimum number of experiments. A L-9 orthogonal array (four factors in three levels) was employed to evaluate effect of concentration (100, 500, 1000 ppm), temperature (25, 40, 60 degrees C), flow rate (0.07, 0.7, 1.2 mL/s) and voltage (10, 20, 30 V) on separation percent of the individual ions in the solution. The results show that increasing concentration, voltage and temperature improves cell performance; however, the separation percent decreases with increasing flow rate. At concentrations of more than 500 ppm, dependence of separation percent on concentration diminishes. The optimum levels of influential factors, determined for all ions are: concentration 1000 ppm, temperature 60 degrees C, flow rate 0.07 mL/s and voltage 30 V. It was found that performance of an electrodialysis cell is almost independent of the type of ions but strongly depends on the operating conditions and cell structure. It was also found that separation percent of monovalent ions is larger than divalent and trivalent ions (S-Cr < S-Cu, S-Zn, S-Pb < S-Na). For ions of similar valence, separation percent was indicated to be restricted by molecular weight and electrochemical activation energy of the ions (S-Pb < S-Cu < S-Zn).