Effect of operating conditions and input variations on the partitioning of metals in a municipal solid waste incinerator

The partitioning of copper, zinc, cadmium and lead between bottom ash and combustion flue gas was investigated in a municipal solid waste (MSW) incinerator. Material balances were established and transfer coefficients were determined for seven 2-h periods. Statistical analysis of the data allowed assessment of the uncertainty and investigation of the effect of waste input variations as well as process conditions. As a result, 6% of Cu, 54% of both Zn and Pb and 90% of Cd in the waste feed were transferred into the combustion flue gas, the rest was found in the bottom ash. The uncertainty of the partitioning in terms of relative width of 95% confidence intervals was estimated as 33% for Cu, 7% for Zn, 7% for Cd and 21% for Pb. Multiple linear regression indicates that, for the incinerator investigated, changes in combustion parameters have a negligible effect on the transfer coefficients of the selected metals; and the partitioning of Cd and Pb does not correlate significantly with changes in the waste composition. A significant positive regression between the transfer of Cu and the chlorine content of the waste feed was observed. The results of this study are instrumental to determine the waste composition by analysing a single combustion product only.