Characterization of Leachates from Landfills Containing MSW-I Residues

Abstract

The objective of this study was to characterize the leachate collected from landfills containing municipal solid waste incineration (MSW-I) ashes in the range of 20%–100% by weight. Results suggested that the conductivity and concentrations of major cations (Na+,K+,Ca2+) and anions (Cl− and Br−) increased with ash content, while alkalinity decreased with ash content. MSW-I ash contents had little effect on pH, TOC, NH4+, trace metals, and SO42−. Comparing the metal composition in the MSW-I ashes and associated ash monofill leachate, the leaching of metals, including Mg, Fe, Cu, Ni, and Al, were not as significant as expected. As, Cd, Pb, and Zn in ash monofill leachate were even below the quantification limit. The effect of MSW-I ash on landfill systems is further discussed. Leachate containing the MSW-I ash might increase the risk of leachate collection system (LCS) clogging. The risk of mineral precipitation in the LCS increased with the ash content mainly due to the increasing concentration of Ca. High ionic strength as well as the high anion ratio of the leachates might increase the hydraulic conductivity of geosynthetic clay liners (GCLs).