[Leaching characteristics of heavy metals in MSW fly ash under different condition]

The leaching characteristic of heavy metals in MSW fly ash was studied under acidic and alkaline condition. The result showed the leaching characteristic of Pb, Zn, Ni, Cr and Hg had similar law, which was these heavy metals could leach out under acidic condition and alkaline condition (pH > 12), and the leaching amount increased with the leachate density or L/S increasing. For example, under acidic and alkaline condition, the leaching amount of Pb increased from 0.457 mg/kg, 51.142 mg/kg to 104.576 mg/kg, 59.692 mg/kg respectively when L/S increased from 20 to 40. Cd and Cu could leaching out only under acidic condition. Under acidic condition the leaching rate of Cd, Pb and Zn were higher then the others.