Utilization of industrial waste for cadmium removal from water and immobilization in cement

The present study investigates the adsorption potential of metal sludge (a waste product of the electroplating industry) for the removal of cadmium from water. The adsorption capacity of the waste sludge for cadmium was ca. 40 mg g−1 at 25 °C. The adsorption was studied as a function of contact time, concentration and temperature by batch experiments. The adsorption has been found to be endothermic and data conform to the Langmuir model. The analysis of kinetic data indicates that the present adsorption system followed pseudo-first-order kinetics. After the adsorption studies, the metal-laden sludge adsorbent was immobilized in cement for its ultimate disposal. Physical properties such as initial and final setting time and the compressive strength of cement-stabilized wastes were tested to investigate the effect of the metal-laden sludge. The results of the present study clearly reveal that waste metal sludge can be used beneficially in treating industrial effluents containing cadmium and safely disposed of by immobilizing into cement. The proposed technology provides a two-fold advantage of wastewater treatment and solid waste management.