Abstract
The entrained fine fly ash particles carried into the post-combustion region and collected by air pollution control devices were capable of such surface-mediated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) formation. The secondary formation of PCDD/Fs in the flue gas and ash from the municipal solid waste incinerator (MSWI) systems has attracted considerable public concern. The objective of this study was to examine reactions in fly ash from an municipal solid waste incinerator (MSWI) operated with metal chlorides and chlorinated aromatic precursors. When 10 wt% FeCl2, ZnCl2 and CuCl2 were added onto the fly ash medium, the PCDD/Fs concentration is 8.8, 25.5 and 369.5 ng/g, respectively. This indicates that the formation of PCDD/Fs was significantly increased by CuCl2. In the case of CaCl2 addition, the results showed that it acts in a minor role as a catalyst to promote the formation of PCDD/Fs. In addition, the results of adding HgCl2 has no transformation effect on the formation of PCDD/Fs in the residue and gas phases. Moreover, in an experiment using chlorinated aromatic precursors, the formation of PCDD/Fs was significantly increased by pentachlorophenol (PCP). This study suggests that the filter cake ash treatment should be studied extensively to control dioxin yields on the fly ash matrix.
Highlights
The mixture of refuse, hazardous household waste, and discarded tires can be problematic when combined with poor combustion conditions, resulting in significant levels of trace pollutant formation (Hu et al, 2009; Wang et al, 2010; Lin et al, 2010)
The entrained fine fly ash particles carried into the post-combustion region and collected by air pollution control devices were capable of such surface-mediated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) formation
The results show that when the fly ash medium are mixed with FeCl2, ZnCl2 and CuCl2, the PCDD/Fs concentration is 8.8, 25.5 and 369.5 ng/g, respectively
Summary
The mixture of refuse, hazardous household waste (plastic bags, paints, solvents, metal-containing substances, discarded electronic waste), and discarded tires can be problematic when combined with poor combustion conditions, resulting in significant levels of trace pollutant formation (Hu et al, 2009; Wang et al, 2010; Lin et al, 2010). Exhaust fume emissions from the incineration process include heavy metals, suspended solids, SOx, NOx and organic contaminants such as dibenzop-dioxin and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), all of which can have serious effects on humans and. The degradation of carbon structures forms small molecule substances, and the interaction forms PCDD/Fs (Lundin and Marklund, 2007). Luijk and Kishi found that 2,4,6-trichlorophenol formed PCDD/Fs, with the main product based on PCDDs, and two forms of 2,4,6trichlorophenol with a similar structures release OH and Cl on chlorophenol and integrate as 1,3,6,8-TCDD or 1,3,7,9TCDD (Luijk et al, 1994; Kishi et al, 2009). Flue gas and ash from incinerators tend to contain unburned carbon, heavy metals, and organic toxic substances, including
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