Influence of ligands on metals leachability from landfilling bottom ashes

After municipal solid waste is incinerated, its bottom ash used to be disposed by landfill. Although the leachate quality is less polluted, some heavy metals in the bottom ashes are affected by ligands, which raise their release potential. Concerned by the bottom ashes landfilling, this research explored the influence strengths of ligands in leaching heavy metals, by rotary extraction and lysimeter leaching test. The results from extraction proved that with the rising concentration of extraction solutions of HCO3-, CO32- and NH3, the released amount of Cu was most likely to exceed the local effluent standard in Taiwan. The lysimeter leaching test achieved the same results as those of extraction and it proved that the results of extractive process could be applied to the landfill site. The results from these experiments confirmed that the extraction could simulate the release of Cu and predict the accumulation of released amounts of Cu in the leachate from landfill of bottom ashes. The statistic regression formulas obtained from this research were feasible, since they could highlight the release trend of Cu concentration, although they were unable to predict the trend precisely. (C) 1998 Elsevier Science B.V.