Abstract: In this study, eight fly ash samples and three bottom ash samples from different areas are collected for analysis of their physicochemical properties and emission content of dioxin precursors and metals. Their surface characteristics, their effects on dioxin precursors, and important aspects of the compositions of residual ash (fly ash and bottom ash) are investigated. Poly-chlorobenzenes (PCBzs) in the fly ash of a fluidized bed incinerator (FBI) are 7.35 to 357.94 µg/kg, and in that of a fire grate incinerator (FGI) are 6.74 to 96.52 µg/kg. The concentrations in bottom ash are the same (i.e., 2.23 to 2.99 µg/kg) regardless of the furnace type. The concentrations of polycyclic aromatic hydrocarbons (PAHs) in FGI fly ash samples (0.293 to 1.783 mg/kg) are less than these in samples from FBIs (1.820 to 38.012 mg/kg). Low boiling point PAHs (mainly 2- and 3-ringed PAHs) and high boiling point PCBzs (mainly H_xCB and P_eCBz) are the major constituents of residual ash. Different distributions of PCBzs and PAHs are mainly dictated by the incineration characteristics of FBI and FGI. Al and Fe, as non-toxic “light metals” are the major constituents of the residual ash, and Ni and Zn as non-toxic heavy metals play important roles in the total heavy metal. Cu, Pb, and Cr are the three major toxic heavy metals. The correlation of the metals and the dioxin precursors is discussed and distinguished.

Key words: Residual ash, Poly-chlorobenzenes (PCBzs), Polycyclic aromatic hydrocarbons (PAHs), Heavy metal, Municipal solid waste incineration (MSWI)

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