Fate of polychlorinated dibenzo-p-dioxins and dibenzofurans in a fly ash treatment plant
- National Cheng Kung University, Tainan (Taiwan). Department of Environmental Engineering and Sustainable Environment Research Center
To understand the fate of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in a fly ash treatment plant that used the Waelz rotary kiln process (hereafter the Waelz process), the samples of input and output media were collected and analyzed. The most important PCDD/F source in input mass was electric arc furnace (EAF) fly ash, which had a mean PCDD/F content of 18.51 ng/g and contributed more than 99% of PCDD/F input mass, whereas the PCDD/F input mass fractions contributed by the coke, sand, and ambient air were only 0.04%, 0.02%, and 0.000002%, respectively. For the PCDD/F output mass in the Waelz process, the major total PCDD/F contents of 43.73 and 10.78 ng/g were in bag-filter and cyclone ashes, which accounted for approximately 69% and 17%, respectively, whereas those of stack flue gas and slag were 14% and 0.423%, respectively. The Waelz process has a dechlorination mechanism for higher chlorinated congeners, but it is difficult to decompose the aromatic rings of PCDD/Fs. Therefore, this resulted in the accumulation of lower chlorinated congeners. The output/input ratio of total PCDD/F mass and total PCDD/F international toxicity equivalence (I-TEQ) was 0.62 and 1.19, respectively. Thus, the Waelz process for the depletion effect of total PCDD/F mass was positive but minor, whereas the effect for total PCDD/F I-TEQ was adverse overall. 20 refs., 3 figs., 6 tabs.
- OSTI ID:
- 20978235
- Journal Information:
- Journal of the Air and Waste Management Association, Vol. 57, Issue 9; Other Information: ylwu@mail.ncku.edu.tw; ISSN 1047-3289
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
DIOXIN
BENZOFURANS
FLY ASH
WASTE PROCESSING
WASTE PROCESSING PLANTS
CHLORINATED AROMATIC HYDROCARBONS
CYCLONE SEPARATORS
COKE
SAND
AIR
ELECTRIC ARCS
ARC FURNACES
FLUE GAS
SMELTERS
TOXICITY
KILNS
HAZARDOUS MATERIALS
FABRIC FILTERS
SLAGS
DECHLORINATION
METAL INDUSTRY