TRACE-METAL ANALYSIS OF SIZE-FRACTIONED MUNICIPAL SOLID-WASTE INCINERATOR FLY-ASH AND ITS LEACHATES

Increased concern over the long-term fate of municipal solid waste (MSW) incinerator ash has motivated investigations to ascertain the potential toxicity of heavy metals which leach from ash disposal facilities. Municipal solid waste incinerator fly ash was separated into seven size fractions ranging from less than 20 mum to greater than 250 mum and analyzed for metal content using a series of neutron activation analysis (NAA) techniques. The regulatory TCLP extraction was then performed on each size fraction and the leachates were analyzed using inductively-coupled plasma (ICP). Neutron activation analysis and ICP are complimentary trace element analysis methods which achieve multielemental evaluation from parts-per-billion to parts-per-million levels. The elemental concentrations of the fractionated fly ash were compared to those of soil. The concentrations of metals in the leachates were compared to the metal content of the ash and the Toxicity Characteristic Leaching Procedure regulatory standards. The resulting pH of the extraction fluid and the buffering capacity of the ash seemed to have a greater effect on the metal levels in the leachate than did the actual metal concentration in the various sized ash particles.