De Novo Formation of Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzofurans during the Gas Cooling Process in a Solid Waste Incinerator

The de novo formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) caused by the interaction between fly ash and flue gas was investigated. In these experiments, flue gas from the laboratory-scale fluidized-bed incinerator was passed through an electrically heated flow reactor in which fly ash obtained at the same laboratory-scale incinerator has been filled. The results show that PCDD/Fs formed in where large amount of fly ash has been deposited by the internal force and thermo-phoresis. In the case of the de novo formation, PCDDs/DFs concentration is proportional to the HCl concentration in the flue gas. It is also noted that PCDDs/DFs are not formed at the temperatures around 200°C but significant PCDDs/DFs formation was observed at around 300°C and also that Cu content in the fly ash at the level of 10wt% strongly promote PCDDs/DFs formation at not only 300°C but also 200°C.