COMPREHENSIVE APPROACH TOWARD UNDERSTANDING ELEMENT SPECIATION AND LEACHING BEHAVIOR IN MUNICIPAL SOLID-WASTE INCINERATION ELECTROSTATIC PRECIPITATOR ASH

A comprehensive approach was used to characterize speciation and leach ing behavior of major, minor, and trace elements in electrostatic prec ipitator (ESP) ash from a Canadian MSW incinerator. Neutron activation analysis (NAA), X-ray powder diffraction (XRPD), scanning electron mi croscopy/X-ray microanalysis (SEM/XRM), Auger electron spectroscopy (A ES), secondary ion mass spectrometry (SIMS), and X-ray photoelectron s pectroscopy (XPS) were used to quantify elements, describe particles a nd phase associations, identify bulk and surface mineral phases, and i dentify the speciation of elements. SEM/XRM showed a complex polycryst alline material covering aluminosilicate spheres. XPS, as a surface te chnique, provided information on speciation at the particle surface wh ere leaching first occurs. SIMS showed molecular fragments indicative of speciation and enrichment of volatile species (K, Zn, Cl, S, Pb) in the fine polycrystalline material. Many of these phases readily disso lve during leaching. Dissolution behavior and pH-dependent leaching co uld be modeled with the geochemical thermodynamic equilibrium model MI NTEQA2. The ability to model leaching behavior provides an opportunity to examine possible disposal or treatment behavior.