In this paper, ultrasonic treatment, electrocoagulation and the combinations of these treatments were compared for the removal of manganese, nickel, cobalt, cadmium and chromium from a synthetic solution. Experiments were conducted using aluminium electrodes in a modified ultrasonic bath. The experimental design approach (DOE) and multi-level categoric design were used to design the experiments and optimize the results. The results show that ultrasound largely affects the EC heavy metals removal process and leads to higher efficiencies than EC alone.
