| dc.description.abstract | Electric arc furnaces (EAFs) and industrial waste incinerators (IWIs) are major emission sources of dioxins in Taiwan. For EAFs, the flue gases were sampled after CO converter, prior to baghouse and stack to measure dioxin concentrations and to investigate the characteristics of PCDD/F congener distribution. Dioxin emissions at stages of oxidation and reduction at an EAF were also characterized. Besides, slag, BF ash, and cyclone ash were sampled and analyzed. In EAF, the PCDD/F concentration emitted at oxidation stage is higher than that during reduction stage for all sampling points, including the points of CO converter outlet, prior to baghouse and stack. The removal efficiency (86.2 %) of particulate-phase PCDD/Fs was higher than that in gas phase (35.6 %) with fabric filtration. BF ash has the highest PCDD/F concentration (31.2 ng/g) of all ashes sampled. As for IWI, WET-EP applied achieves a higher removal efficiency for particulate-phase PCDD/Fs (90.5 %) than that in gas-phase. The removal efficiency (84.5 %) of gas-phase PCDD/Fs was significantly higher than that in particulate-phase with fixed carbon bed. PCDD/F concentration of EP washing sludge is the highest (5,313 ng/g) in IWI. It is important to note that the washing water is circulated for reuse, therefore, PCDD/Fs accumulate in that, resulting in its high PCDD/F concentration. Major contributors to the dioxin concentrations at each sampling point of EAF and IWI include 1,2,3,4,6,7,8-HpCDF, OCDD and OCDF. 2,3,4,7,8-PeCDF contributes about 50 % Toxic Equivalent Quantity (TEQ) concentrations at each sampling point. | en_US |