Heavy Metal Leachability From Solid Waste Incinerator Ashes

Abstract

The leachability of heavy metals in municipal solid waste (MSW) incinerator residues was evaluated using equilibrium leach tests and the sequential chemical extraction procedure. Incinerator bottom ash, boiler and economizer fly ashes were sampled from a full-scale two-stage combustion facility without pollution-control devices. Fly ashes were also collected from a pilot-plant scale, lime-based flue-gas scrubber system, connected to a mass burning incinerator facility. Generally, bottom ashes contained low to moderate concentrations of cadmium, copper, lead and zinc which are relatively insoluble under normal landfill leaching conditions. Fly ashes contained relatively moderate concentrations of cadmium and copper and much higher concentrations of lead and zinc which are readily available for leaching under normal landfill conditions. Metal leachability appears to be dependent upon metal speciation, the pH of the leaching medium and ash particle size.