Cadmium Stabilization by Sewage Sludge Incineration Ash

Abstract Cadmium (Cd), as a common ingredient in the production process of nickel cadmium batteries, can lead to functional disorder in kidneys, liver, lungs, cardiovascular, immune and reproductive systems. Previous studies have shown that cadmium can be stabilized in ceramic systems using clay as precursor, but the excessive exploitation of nonrenewable clay resources has caused great concerns. Hence, it is essential to find alternatives to substitute nonrenewable clay minerals. Sewage sludge incineration residues, with oxides of aluminum and silicon as major component, have attracted much attention because of the potential resource utilization. In this study, CdO and CdNO 3 was used to simulate cadmium-bearing industrial waste, and the stabilization of cadmium was achieved in ceramic matrix provided by the residues of sewage sludge incineration. Through a 2-hour sintering procedure at temperatures ranging from 800°C to 1000°C, cadmium was found to be incorporated into CdAl 2 Si 2 O 8 . The leachability of cadmium significantly declined in sintered samples when extracted in acidic environment. Meanwhile, samples that were pressed into pellets showed better cadmium stabilization efficiency, compared with powder samples. Therefore, this study suggests a promising technique to stabilize cadmium by the utilization of sewage sludge incineration residues as ceramic precursors. The success implementation of current study will further reduce the environmental burden caused by the release of heavy metals from industrial waste. Moreover, the recycling of sewage sludge incineration residues can be realized, and a waste-to-resource strategy is expected.