The main purpose of this study was to investigate the adsorption characteristics of cobalt, nickel and copper ions, which are harmful heavy metals released from various industries, in single, binary and ternary systems. The results showed that the adsorption extent decreased as the system changed from a single to a ternary system but adsorption percentages were not below 79%. The adsorption percentage of cobalt ion was superior to that of the other ions regardless of the type of system. In this study, the Langmuir isotherm was adapted for every adsorption result, and an extended version of the Langmuir isotherm was employed for the binary and ternary systems. The q_max value became smaller and K_L value increased in the binary and ternary systems compared with that of the single system. The equilibrium parameter (R_L) was between 0 and 1 under every condition, which indicated that adsorption was favorable. Finally, an adsorption experiment for real wastewater was performed, and the results were compared with those obtained for artificial wastewater.