Flow analysis of heavy metals in MSW incinerators for investigating contamination of hazardous components.

The contribution of hazardous components in municipal solid waste (MSW) to environmental risks has seldom been quantified due to their heterogeneous streams and irregular disposal patterns. A material flow analysis, in which the input metals in major MSW compositions (excluding discriminable hazardous components) were subtracted from the total output metals in the treatment products, was proposed to estimate the heavy metal contamination in MSW due to hazardous components. The statistical data from 1-year field measurements for two large-scale incinerators in Shanghai city were used as an illustrative example. The results indicated that the amount of Cr and Ni in the incineration products were similar to those found in the major MSW compositions, while the amounts of Cd, Cu, Pb, and Zn in the incineration products were 2.27-4.00 times, 1.90-3.77 times, 2.25-3.51 times, and 2.98-4.06 times greater than that in the MSW. According to evaluation, more than 56-75% of Cd, 47-74% of Cu, 56-72% of Pb, and 66-75% of Zn in the MSW were contributed by the minor hazardous components, indicating the need for source separation. The methodology provides a cost-effective procedure for quantification of the hazardous waste contamination in MSW.