Characterization of Flue Gas Residues from Municipal Solid Waste Combustors

Solid residues recovered from treatment of flue gas resulting from the combustion of municipal solid waste (MSW) are of particular concern because of ever-increasing worldwide production rates and their concentrations of potentially hazardous transition elements and heavy metals. Three main residue types have been studied in this study: electrostatic precipitator ashes, wet filter cakes, and semidry scrubber residues. Using a large number of residues from two French MSW combustion (MSWC) facilities, the aim of this work is to determine their chemistry and mineralogy in order to shed light on their potential toxicity. We find that pollutant concentrations are dependent not only on the composition of MSW but also on the size of particles and flue gas treatment process. Using a procedure based on leaching, grain-size, density, and magnetic separations, we present a detailed description of the mineralogy of MSWC solid residues. These residues consist of a very heterogeneous assemblage of glasses, metals, and other crystals in which polluting elements are distributed. The results of this characterization will therefore help to contribute to the development of adequate waste management strategies.