Toxicity Analysis of Municipal Solid Waste Incineration (MSWI) Fly Ash

MSWI fly ash requires safe handling due to existence of heavy metals which pose potential threat to people´s health and the environment. In this work, its toxicity was studied by means of leaching toxicity, specification analysis and volatilization analysis of heavy metals in fly ash. It is found that leaching toxicity of Hg, Cd, Zn and Pb exceeds the limit in accordance with the HVEP and ALT standards. Acid soluble forms of Cd, Cu, Ni, Pb and Zn all exceed 20%, and consequently they pose potential threat to the environment where acids exist. In addition, volatility of heavy metals decreases as: Hg>Pb>Cd, As>Zn>Cr, Ni, Cu. It is easy for Hg, Pb, As and Cd to volatilize, which fly away almost entirely at 1150degC. It is relatively difficult for Zn to volatilize, 40%~50% of which flies away at 1150degC, and it is difficult for Cr, Ni and Cu to volatilize, volatilization rates of which are less than 10%.