Ultrafiltration for the removal of cadmium in waste streams from industrial waste incineration

To remove Cd in waste streams from industrial waste incineration plants, a process of tangential ultrafiltration preceded by complexation was used. It was shown that the optimal pH for precipitation of metallic hydroxides was between 10 and 11, which is greater than the value (8.5) stipulated by the national standard for waste streams. A dozen products were tested in order to choose a suitable complexing agent, including Metalsorb ZT (Na-dimethyldithiocarbamate) which seemed to be the most efficient for reducing the Cd content. For additions of Metalsorb ZT from 0.25 to 2.5% in volume and in the pH 7-9 range, the Cd content was reduced by approximately 75%. The process did not seem particularly sensitive to fluctuating operating conditions.