This study evaluates the adsorption performance of a zeolite and iron scrap mixture (75:25%) in reducing cadmium and zinc in the Babol landfill using a fixed-bed column experiment. Results showed that the effluent zinc concentration at depths of 20 cm after 18 days and 40 cm after 23 days remained below the permissible limit, while cadmium at the same depths maintained safe performance for 10 and 18 days, respectively, indicating that cadmium is more critical in adsorbent design. Using the Thomas and Yoon–Nelson models, the specific adsorption capacity (q₀) for zinc was 4.23 and 14 mg/g at 20 and 40 cm depths, respectively, and for cadmium 0.6 and 0.44 mg/g. The Thomas rate constant (kTh) for zinc was 0.001 and 0.0009 L/day·mg, and for cadmium 0.43 and 0.3 L/day.mg. The breakthrough half-time (τ) was 68 and 72 days for zinc, and 37 and 52 days for cadmium. The decrease in q₀ with increasing depth is due to the lower allowable effluent concentration and early termination of the test, leaving part of the adsorbent unused; thus, the Thomas model does not reflect the true potential capacity of deeper columns. Additionally, the rate constant decreased with increasing depth because of longer contact time. Finally, the adsorbent thickness was designed to keep the effluent concentration below the standard limit.