Leachability of pollutants from solid residues of a hazardous waste incinerator

Leachability of pollutants including heavy metals, total organic carbon (TOC) and halogens from solid residues of a hazardous waste incinerator was evaluated. Leaching tests were applied to the solid residue samples (bottom ash, fly ash, filter cake and gypsum) taken in nine trial burns at different times, and results were evaluated in relation to the waste composition and from the toxicity point of view. Origins of the pollutants and their distribution between the types of wastes were also studied. The results showed that the bottom ash contains soluble organics at high levels due to cold points and pyrolytic conditions that could occur locally in the kiln causing formation of products of incomplete combustion. The fly ashes were characterized by high metal concentrations in leachates, while those of the filter cake and the gypsum wastes had high sulfate concentrations. More than half of the Cd input was detected in the leachates, especially in the fly ash, showing its affinity to form soluble compounds.