Heavy metals partitioning in waste incineration

Over the past years, many efforts have been made towards improving the efficiency of flue gases treatment in waste incineration in order to meet the more and more stringent limits prescribed for emissions of acid gases and toxic organic compounds. Conversely, less attention has been devoted to the investigation of heavy metals behavior during combustion. Heavy metals can deserve special attention, due to the enrichment phenomena usually observed onto small solid particles. Heavy metals release due to waste incineration depends not only on the concentrations in the waste itself, but mostly on the physical mechanisms and chemical transformations acting during combustion, which can greatly affect heavy metals partitioning among the different residues. Some highly volatile metals, in spite of their relatively low concentrations ill the untreated waste can therefore be present at very high concentrations (thus showing very high enrichment factors) in fly ash or in flue gas dust. In the present paper a number of data concerning partitioning of some typical lithophilic and volatile metals as detected in full-scale Hospital Solid Waste (HSW) incineration plant are presented.