Volume 12, No. 6, December 2012, Pages 1345-1354 PDF(258 KB)
Distribution of Polybrominated Diphenyl Ethers (PBDEs) in a Fly Ash Treatment Plant
Wei-Tung Liao1, John Kennedy Mwangi2, Hsiao-Hsuan Mi3, Lin-Chi Wang4,5, Li-Kai Tu2, Guo-Ping Chang-Chien5,6
1 Department of Chemical and Materials Engineering, Southern Taiwan University of Science and Technology, No. 1, Nan-Tai Street, Yungkang Dist., Tainan 71005, Taiwan
2 Department of Environmental Engineering, National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan
3 Department of Environmental Engineering and Science, Chia-Nan University of Pharmacy and Science, No. 60, Sec. 1, Erren Rd., Rende Dist., Tainan 71710, Taiwan
4 Department of Civil Engineering and Engineering Informatics, Cheng Shiu University, 840, Chengching Road, Kaohsiung 833, Taiwan
5 Super Micro Mass Research and Technology Center, Cheng Shiu University, 840, Chengching Road, Kaohsiung 833, Taiwan
6 Department of Chemical and Materials Engineering, Cheng Shiu University, 840, Chengching Road, Kaohsiung 833, Taiwan
PBDES are used as the flame retardants and have adverse effects on human health. Electric arc furnaces (EAF) are one of major emission source of PBDEs. The PBDE contents in the fly ashes of an EAF (29.3 ng/g) examined in this study were one to three orders higher than those in environmental soils. EAF fly ash treatment plants are established to resolve the disposal of this material, and also to recover the remaining iron or zinc from it. However, very little is known about the fate of PBDEs in EAF fly ash treatment plants. The EAF fly ash treatment plant investigated in this work can be divided into three sub-systems, including a pelletizer, reducing furnace and submerged arc furnace (SAF). The fly ash generated from the pelletizer process exhibited the highest PBDE content (7.69 ng/g), and contributed about 91% of the total PBDE inputs (4.40 g/day). The total PBDE concentrations in the stack flue gases of the pelletizer, reducing furnace and SAF were 24.5, 2.88 and 4.71 ng/Nm3, respectively. The high PBDE concentrations of the pelletizer resulted from not only the thermal desorption of lighter brominated congeners, but also fugitive particles of EAF fly ashes. Together, the three stacks accounted for 40.8% of the total PBDE outputs, revealing that the air pollution control devices deployed in the current study were not very effective with regard to removing PBDEs from the flue gas. The PBDE output/input ratio of the EAF fly ash treatment plant was 0.0378, and thus most PBDEs introduced into the system were decomposed. The EAF fly ash treatment plant examined in this work is thus a reliable facility with regard to the disposal of this material.
Fly ash treatment plant; PBDEs; Mass distribution; Stack flue gas.