Heavy metal dissolution from fly and bottom ashes, and the evaluation of performance for heavy metal sorption by clay barrier materials in land fill sites

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The major heavy metals in the leachate for fly and bottom ash collected from a incineration plant was Pb, Cu and Zn, and their concentration level was different according to the solution pH for leaching. The dominant salt in the leachate were Na K, and Ca, which amounted to 800 mg/L in Na and K at an initial leaching stage.The column leaching for bentonite (5%)-added soil indicated that sorption capability for Pb was greater in volcanic soil with allophone than basalt soil with halloysite. For Pb retention, carbonate and exchangeable phase was predominant for the volcanic soil and metal oxides were for the basalt soil. In a column test for marine clay, Pb in pore water accumulated in the top layer of the column soil for the pure water while distributed throughout depth for sea water and ash leachate.