Release of heavy metals from waste into leachate in active solid waste landfill

Mass balance of selected heavy metals (Cu, Cr, Pb, Hg, Zn, Cd) released from waste into leachate during 8 years of landfill exploitation has been calculated. The average release of all analyzed heavy metals did not exceed 1.7%. Heavy metals released in the largest quantities were Cr (0.025 –1.685%), Hg (0.033–1.540%) and Cd (0.082–0.701%). Release of Pb, Cu, Zn was 0.008–0.152%; 0.012–0.085% and 0.007–0.152%, respectively. Cr and Hg do not form an insoluble sulfide precipitate and that is why they are released in a larger amount. Cd and Pb concentrations are positively correlated with the amount of the atmospheric precipitation and the amount of leachates, which means that infiltrating rainfall can leach out these metals from waste. Favorable conditions for leaching of these metals are probably a result of their precipitation as carbonates. A strong correlation between Cu, Zn, and Cr indicates they do not precipitate as carbonates and further they can be subject to desorption processes. In the case of Cu, Zn, Cr and Hg, a positive correlation with the amount of deposited waste was also observed.