The Leaching toxicity in the MSWI Fly Ash treated by Enhanced Electrokinetic Removal Technology

The municipal solid waste incineration fly ash is the secondary contamination in municipal solid waste incineration. Fly ash from municipal solid waste incineration (MSWI) contains high concentrations of heavy metal and other toxic components. The main environmental impact from utilization and disposal of waste incineration residues arise from the release of contaminants to the surrounding environment by leaching. Due to the potential leaching toxicity of these components when the ash is land filled, the MSWI fly ash is regulated as hazardous waste in many countries. Electrokinetic removal was first applied to solid remediation, has gradually shown its ability for removing heavy metal from MSW fly ash. Before the enhanced electrokinetic removal experiment, the average leach quantity in the original fly ash of Zn, Cd and Pb were 122.15 mg/l, 4.35 mg/l and 8.02 mg/l, respectively. All of those three elements (Zn, Cd, Pb) exceeded the standard value of the Standard for Pollution Control on the Landfill Site of Municipal Waste Solid (GB16889-2008), especially cadmium and lead. After the MSWI fly ash was treated by enhanced electrokinetic removal experiment for 5 days and 10 days, it is easy to see that enhanced electrokinetic experiment makes positive contribution to the removal of the heavy metal, especially lead element. The range of removal efficiency of lead element was even from 51.62% to 76.31%. That of zinc element was from 20.04% to 40.86%. And the range of removal efficiency of cadmium was from 17.70% to 29.88%. However, only leach quantity of zinc element in those three kinds of heavy metal was less than the standard value of the Standard for Pollution Control on the Landfill Site of Municipal Waste Solid.