Stack Flue Gas Research Articles

Distribution of Polybrominated Diphenyl Ethers (PBDEs) in a Fly Ash Treatment Plant

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.

Pd–Pt bimetallic catalysts for combustion of SOFC stack flue gas

Pd–Pt bimetallic as well as monometallic Pd and Pt catalysts were evaluated to study the catalyst activity and stability for combustion of SOFC stack flue gas. The simulated reactant gases consisting of H2, CO, CH4, air and water vapor were tested at two different GHSV for obtaining the behavior of catalyst activity versus temperature and catalyst stability versus on-stream operation hours. As H2 and CO were readily combusted under 200°C and CH4 was combusted only above 300°C, catalyst activity was evaluated by measuring CH4 conversion as a function of temperature for all five catalysts. Catalyst stability was evaluated by monitoring CH4 conversion for 1:1 Pd–Pt and 1:3 Pd–Pt catalysts exhibiting relatively better activity at 427 and 627°C for 200h. 1:1 Pd–Pt catalyst was the most active one based on the lowest CH4 light-off temperature and the lowest temperature for complete CH4 conversion, and this catalyst was deactivated less than 1:3 Pd–Pt catalyst in the 200h-stability test. 1:1 Pd–Pt composition was attributed as the synergistic factor of active metal ingredients affecting the catalyst activity and stability. The presence of water vapor in the reactant gas inhibited catalyst activity and stability strongly by forming some less or inactive palladium species on catalyst surface via interaction between water molecules and catalyst active sites.

Polybrominated diphenyl ethers in various atmospheric environments of Taiwan: Their levels, source identification and influence of combustion sources

In this study, ambient air samples from different atmospheric environments were examined for both PBDE and PCDD/F characteristics to verify that combustion is a significant PBDE emission source. The mean±SD atmospheric PBDE concentrations were 165±65.0pgNm−3 in the heavy steel complex area and 93.9±24.5pgNm−3 in the metals complex areas, 4.7 and 2.7 times higher than that (35.3±15.5pgNm−3) in the urban areas, respectively. The statistically high correlation (r=0.871, p<0.001) found between the atmospheric PBDE and PCDD/F concentrations reveals that the combustion sources are the most likely PBDE emission sources. Correspondence analysis shows the atmospheric PBDEs of the heavy steel and metals complex areas are associated with BDE-209, -203, -207, -208, indicative of combustion source contributions. Furthermore, the PBDEs in urban ambient air experience the influence of the evaporative releases of the commercial penta- and octa-BDE mixtures, as well as combustion source emissions. By comparing the PBDE homologues of indoor air, urban ambient air, and stack flue gases of combustion sources, we found that the lighter brominated PBDEs in urban ambient air were contributed by the indoor air, while their highly brominated ones were from the combustion sources, such as vehicles. The developed source identification measure can be used to clarify possible PBDE sources not only for Taiwanese atmosphere but also for other environmental media in other countries associated with various emission sources in the future.

Distribution of Polybrominated Dibenzo-p-dioxins and Dibenzofurans and Polybrominated Diphenyl Ethers in a Coal-fired Power Plant and Two Municipal Solid Waste Incinerators

In this study, the distributions of polybrominated dibenzo-p-dioxins (PBDD/Fs) and dibenzofurans and polybrominated diphenyl ethers (PBDEs) in the bottom residues of the combustion chambers (BR), the fly ashes from superheaters (SH), economizers (EC), semi-dry scrubbers (SDA), fabric filters (BF), fly-ash pits (FAP) and stack flue gases (SFG) of two municipal solid waste incinerators (MSWIs) and the bottom residue (BR), electrostatic dust precipitators (ESD), and stack flue gases (SFG) of a coal-fired power plant (TPP) were investigated. BR of combustion chambers exhibited the highest content of PBDEs and PBDD/Fs among all the units. The amount of PBDE mass found in bottom residues constituted 99.7% at MWSI-A, and 92.6% at MSWI-B and 75.1% at TPP of the total PBDE discharges, respectively; while the second highest PBDE mass observed in MSWI-A and MSWI-B was from SFG (0.146%) and EC (5.54%), respectively. In TPP, the PBDE distribution was 75.1% in BR, 12.5% in ESD, and 12.4% in SFG. The mean concentrations of PBDEs emitted from SFG of MSWI-A, and MSWI-B were 9.32 ng/Nm3, and 7.62 ng/Nm3, respectively; however, that of PBDE discharged from SFG of TPP was only 5.43 ng/Nm3. The dominant congener found from MSWI-A,MSWI-B and TPP, was BDE-209, accounting for 65.9%, 77.7%, and 77.6% of total PBDE concentrations in SFG, respectively; whereas BDE-206 (6.01%–6.36%) was the second highest congener. Meanwhile, the PBDE emission factors from the stack flue gases were 35.6 ± 10.9 μg/ton-waste at MWSI-A, 47.6 ± 29.4 μg/ton-waste at MSWI-B and 62.9 ± 10.9 μg/ton-coal at TPP of the total PBDEs, respectively; showing the PBDE emission rates and contributions of TPP to the ambient air are actually much higher than those of MSWIs, while the PBDE concentrations in SFG of TPP were lower than MSWIs’. Further investigations on the safety of BR reutilization and the impact of SFG from TPP are strongly advised.

Emissions of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from an Electric Arc Furnace, Secondary Aluminum Smelter, Crematory and Joss Paper Incinerators

Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from the stack flue gases, fly ashes and bottom ashes of various stationary sources were investigated. The mean total PCDD/F I-TEQ concentration of flue gas ranged from 0.00681 to 0.703 ng I-TEQ/Nm 3 . However, the emission factor of PCDD/F from various incinerators was 0.00827 to 3.50 µg I-TEQ/ton, whereas it was 5.36 µg I-TEQ/body for a crematory (CM). In addition, the mean total PCDD/F I-TEQ content in fly ash from an electric arc furnace (EAF) and a secondary aluminium smelter (secondary ALS) were 74.0, and 49.9 ng I-TEQ/kg, respectively, whereas they are 21.3 and 0.494 ng I-TEQ/kg for bottom ash. Meanwhile, the removal efficiency of PCDD/F by bag filters from EAF was –44.4% which is attributed to the “memory effect”. The indicatory PCDD/Fs of EAF, and secondary ALS have the same congeners (1,2,3,7,8,9-HxCDF, 2,3,7,8-TeCDF, and 1,2,3,7,8-PeCDF). In addition, CM, joss paper-A (JP-A) and joss paper-B (JP-B) incinerators have similar indicatory PCDD/F (2,3,4,6,7,8-HxCDF, OCDF, 1,2,3,4,6,7,8-HpCDD, and OCDD). The high contribution of total PCDD/F is from fly ash (61.1-95.3%) for metallurgical facilities (EAF, secondary ALS), whereas 99.9% contribution of stack flue gas is from JP-A and JP-B. In conclusion, continually monitoring various PCDD/F emission sources is necessary to understand current PCDD/F emission (flue gas, fly/bottom ash) and the related removal efficiency of existing air pollution control devices. Information about both emission factors of PCDD/Fs and indicatory PCDD/F congeners are useful for the establishment of control strategies and for use as fingerprints with regard to the dominant congeners from different emission sources.

Fate and Distribution of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in a Woodchip-fuelled Boiler

As yet, very little is known about the PCDD/F fate and distribution in the woodchip-fuelled boilers. In this study, the feeding woodchips, stack flue gases and the ashes in different units of a woodchip-fuelled boiler are sampled to investigate their PCDD/F characteristics. The PCDD/F contents in the bottom residues and fly ashes ranged from 18.9 to 66.3 ng I-TEQ/kg, which are below the Taiwanese PCDD/F regulation for reutilization of bottom residues, but still higher than PCDD/F limitations on soils for agricultural use (10 ng I-TEQ/kg), which are adopted by several countries. From the PCDD/F output/input ratios, we found that combustion of woodchips in the boiler system is more favourable for the formations of PCDFs by de novo syntheses, especially for lower chlorinated PCDF congeners. Although about half of the input PCDD/Fs mass are destroyed in the combustion, the output PCDD/Fs toxicity are 6.9 times higher than the inputs. Fly ashes exhibited the highest PCDD/F distributions among the woodchip-fuelled boiler. Still 21.4% of total PCDD/F mass and 18.0% of total PCDD/F toxicity were emitted from the stack flue gases due to the lack of control devices for gaseous phase PCDD/Fs. Decreasing de novo syntheses among the boiler systems, deploying control devices for gaseous phase PCDD/Fs, and proper management on the reutilization of fly ashes will ensure woodchip-fuelled boilers as a sustainable and renewable biomass energy.

Characterization of Persistent Organic Pollutants Emitted from a Municipal Solid Waste Incinerator in Taiwan

No information is currently available on the emission of brominated flame retardant (BFR) compounds from stack flue gases of municipal solid waste incinerators (MSWIs) because of the limitations of standard methods of BFR sampling and analysis. This study presents sample cleanup procedures that are combined with a multiple column approach to determine the quantities of five persistent organic pollutants (polychlorinated dibenzo-p-dioxins/dibenzofurans [PCDD/Fs], polybrominated dibenzo-p-dioxins/dibenzofurans [PBDD/Fs], polybrominated diphenyl ethers [PBDEs], polychlorinated biphenyls [PCBs], and polybrominated biphenyls [PBBs]) simultaneously from single stack gas samples collected from a large-scale MSWI in Taiwan. Mean concentrations of PCDD/Fs, PBDD/Fs, PCBs, PBDEs, and PBBs in the flue gases of MSWI were 0.0719 ng WHO-TEQ/(N·m3), 0.00169 ng WHO-TEQ/(N·m3), 0.00546 ng WHO-TEQ/(N·m3), 20.7 ng/(N·m3), and 0.958 ng/(N·m3), respectively. Emission factors of PCDD/Fs, PBDD/Fs, PCBs, PBDEs, and PBBs were 0.300 μg WHO-TEQ/ton-waste, 0.00667 μg WHO-TEQ/ton-waste, 0.0207 μg WHO-TEQ/ton-waste, 84.5 μg/ton-waste, and 1.05 μg/ton-waste, respectively. Therefore, the emissions of not only PCDD/Fs but also BFRs from MSWIs should be of concern and further investigation is needed.

Influence of memory effect caused by aged bag filters on the stack PCDD/F emissions

To our best knowledge, this study is the first research which investigates whether the PCDD/F memory effect could also be caused by bag filters. In this study, the PCDD/F characteristics of the flue gases in front of and behind the bag filters of one municipal solid waste incinerator (MSWI) and two electric arc furnaces (EAFs) were investigated to clarify the memory effect of PCDD/Fs and their influence on emissions. After the bag filters were operated for over four years, the PCDD/F concentrations in the stack flue gases were all higher than those prior to the aged bag filter, rendering a negative PCDD/F removal. This memory effect is because gaseous phase PCDD/Fs are released from the contaminated filters of the aged bag filters. The release of 2,3,7,8-TeCDF, 1,2,3,7,8-PeCDF and 2,3,4,7,8-PeCDF from the contaminated filters of the EAFs increased the PCDD/F concentration and their fractions in the stack flue gases. In contrast, the MSWI exhibited increasing fractions of 1,2,3,4,6,7,8-HpCDD, OCDD after flue gases passed through its aged bag filter. The activated carbon of the MSWI adsorbed more lower chlorinated-substituted PCDD/Fs in the raw flue gases, and the remaining higher chlorinated congeners gradually accumulated on the aged filters, and were released in lower PCDD/F concentration conditions.

Emission estimation and congener-specific characterization of polybrominated diphenyl ethers from various stationary and mobile sources

Here we show that combustion sources, including waste incinerators, metallurgical processes, power-heating systems and so on, are also important emitters of polybrominated diphenyl ethers (PBDEs) to the atmosphere. Geometric mean PBDE concentrations in the stack flue gases of the combustion sources ranged from 8.07 to 469 ng/Nm 3. The sinter plants (24.7 mg/h), electric arc furnaces (EAFs) (11.3 mg/h) and power plants (50.8 mg/h) possessed the largest PBDE emission rates, which were several orders higher than those of the other reported sources. The occurrences of the PBDEs in the flue gases of the power plants and vehicles, as well as their PBDE concentrations statistically highly correlated with combustion-originated PCDD/Fs, revealing that PBDEs should be the products of combustion. The ranking of major PBDE emission sources in Taiwanese PBDE inventory for combustion sources was power plants (30.85 kg/year), vehicles (14.9 kg/year) and metallurgical processes (5.88 kg/year).

Emissions of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) from both of point and area sources of an electric-arc furnace-dust treatment plant and their impacts to the vicinity environments

This study was set out to investigate emissions of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) from both the stack (i.e., point source) and plant fugitives (i.e., area source) of an electric-arc furnace-dust treatment plant (EAFDTP) and their impact to the vicinity environments. The emission rate of the point source (2360 ng I-TEQ h −1) was determined directly by measuring PCDD/F concentrations of the stack flue gas. The emission rate of the area source (1080 ng I-TEQ m −2 h −1) was estimated by using the Industrial Sources Complex Short-Term (ISCST3) model based on concentrations measured at the downwind side of the plant. The mean emission factors of 785 and 893 ng I-TEQ ton −1 ZnO were found for the point and area source, respectively. The above results suggest that the area source accounted for more than 50% of total PCDD/F emissions for the selected EAFDTP. The contribution of the point source to the atmospheric PCDD/F concentrations of the upwind site and downwind site of the EAFDTP were 0 and 0.27 fg I-TEQ Nm −3, respectively. The contributions of the area source were 0.020 and 3.3 fg I-TEQ Nm −3, respectively. The total contribution of the selected EAFDTP (including both the point and area sources) to the concentrations in both upwind and downwind side vicinities were all less than 10%. Finally, the impact of PCDD/F emissions from the selected EAFDTP to the vicinity atmospheric environments was discussed in the present study.

Characterizing the Emissions of Polybrominated Diphenyl Ethers (PBDEs) and Polybrominated Dibenzo-p-dioxins and Dibenzofurans (PBDD/Fs) from Metallurgical Processes

This study investigated the characteristics of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in the stack flue gases of the metallurgical processes. An examination of the PBDEs existing in the stack flue gases of sinter plants revealed that PBDEs can form during the combustion processes through the similar formation conditions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The PBDD/F and PBDE emission rates of the metallurgical facilities were 0.446-3.19 microg TEQ/h and 4470-27000 microg/h, correspondingly. Both emission rates could reach several orders higher than those of the reported sources, revealing that the metallurgical facilities are not only important PCDD/F but also significant PBDD/F and PBDE emission sources to the environment. BDE-209 is the most abundant PBDE congener in the emissions of metallurgical facilities and is found to be dominant in the atmosphere and soils. However, few studies have considered metallurgical facilities as potential PBDE contributors to the environment. Because PBDEs could form or not be completely destroyed in the feeding materials in the combustion system, PBDE contributions from combustion emission sources to the atmosphere should not be ignored and need further investigation.

Distribution of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo- p-dioxins and dibenzofurans (PBDD/Fs) in municipal solid waste incinerators

The stack flue gases and the ashes in different units of two municipal solid waste incinerators (MSWIs) are sampled to investigate the characteristics of polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo- p-dioxins and dibenzofurans (PBDD/Fs), and polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs). Bottom ashes (BA) exhibited much higher PBDD/F (8.11–52.2 pg TEQ/g) and PBDE contents (20.4–186 ng/g) than those of fly ashes (0.0932–2.02 pg TEQ/g and 0.332–25.5 ng/g), revealing that the PBDD/Fs and PBDEs in the feeding waste may not be completely destroyed. The PBDE concentrations/contents in the stack flue gases (26.1–109 ng/Nm 3) and in the BA (20.4–186 ng/g) of the MSWIs could reach three orders higher than those in the atmosphere and reference soils. PBDE contributions to the environment from the stack flue gases or the reutilization of BA of MSWIs should not be ignored from the developing PBDE inventory.

The Emission and Distribution of PCDD/Fs in Municipal Solid Waste Incinerators and Coal-fired Power Plant

The emission and distribution of polychlorinated debenzo-p-dioxins/dibenzofurans (PCDD/Fs) was investigated in two municipal solid waste incinerators (MSWIs) and one coal-fired power plant (PP) in southern Taiwan. Samples were collected from stack flue gases (SFG), bottom residues (BR), super heater (SH), economizer (EC), semi-dry absorber (SDA), bag filter (BF), and fly ash pit (FAP) in MSWIs. Stack flue gases, bottom residues and electrostatic dust collectors (ESD) in PP were also collected. In order to compare the difference between the results of MSWIs and PP, samples from SFG, BS, and FAP in a PP were also determined. Seventeen congeners of PCDD/Fs were analyzed by utilizing a high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS). Distributions of total PCDD/F-I-TEQ in each unit of MSWI-A and MSWI-B were SFG (0.3%, 0.07%), BR (3.9%, 0.62%), SH (0.17%, 0.24%), EC (4.2%, 0.05%), SDA (1.29%, 7.06%), and BF (90.14%, 91.97%), respectively. However, those in SFG, BS, and FAP of PP were 99.58%, 0.17%, and 0.25%, respectively. The above results indicated 99.5% PCDD/Fs were trapped in the fly ash of MWSI. On the other hand, 99.7% PCDD/Fs was emitted to the atmosphere from PP. The results of this study provide useful information for controlling PCDD/Fs in MSWIs and PP.

Cluster Analysis for Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans Concentrations in Southern Taiwan

This study investigates the characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the ambient air of two municipal solid waste incinerators (MSWIs: GS and RW) and a coal-fired power plant (PW) in the Kaohsiung County (KC) area in Taiwan. The results show that the toxic equivalency (TEQ) concentration in the flue gas of GS and RW averaged 0.090 and 0.044 ng international toxic equivalents (I-TEQ)/N·m3, respectively. The TEQ concentration in the flue gas of PW averaged 0.050 ng I-TEQ/N·m3. All PCDD/Fs concentrations from the stack flue gas are lower than the Taiwan Environmental Protection Administration emission standard. Furthermore, the mean I-TEQ concentration in the ambient atmosphere ranged from approximately 0.019 to 0.165 pg I-TEQ/N·m3, much lower than the environmental quality standards for dioxins in Japan (0.6 pg TEQ/N·m3). This work classified all sampling sites into three clusters according to k-means cluster analysis. The result shows a probable direct correlation between the GS incinerator and site C. Although the concentration from the PW plant did not exceed the emission standard, it was much higher than that in Fernández-Martínez’s study. For proper environmental management of dioxins, establishing a complete emission inventory of PCDD/Fs is necessary. The government of Taiwan should particularly pay more attention to power plants to address the information shortage.

Characterization of PCDD/Fs, PAHs, and heavy metals in a secondary aluminum smelter

This study characterizes polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), and heavy metal concentrations in stack flue gas, workplace air, fly ash, bottom ash, and ambient air of a secondary aluminum smelter. The total PAH concentration in workplace air was dominated by 2- and 3-ring PAHs, accounting for 86.2% of the gas phase in the total PAHs. The PCDD/F concentrations in workplace air are 1–7 fold higher than that in ambient air. The mass distribution ratio for total PCDD/Fs was soil > ash > workplace air > ambient air > flue gas. Aluminum and Zn had the highest concentrations. A positive correlation existed between PCDD/Fs and PAHs concentrations (r2 = 0.920). The operation of secondary aluminum smelter affects the pollutant concentrations and surrounding air quality. Experimental results suggest that besides the terminal control technologies for stack flue gases, engineering control technologies in the workplace need further improvement.

Emissions of polycyclic aromatic hydrocarbons from fluidized and fixed bed incinerators disposing petrochemical industrial biological sludge

This study investigated the emissions of polycyclic aromatic hydrocarbons (PAHs) from two fluidized bed incinerators (FLBI_A and FLBI_B) and one fixed bed incinerator (FIBI) disposing biological sludge generated from the petrochemical industries in Taiwan. The results of 21 individual PAHs (including low (LM-PAHs), middle (MM-PAHs) and high molecular weight PAHs (HM-PAHs)) were reported. The LM-PAHs mainly dominated the total-PAHs in the stack flue gases, whereas the LM- and HM-PAHs dominated the total-PAHs in the bottom fly, fly ash and WSB effluent. Due to high carcinogenic potencies (= total-BaP eq concentrations) in the bottom ash (195 ng g −1) and WSB effluent (20,600 ng L −1) of the FIBI, cautious should be taken in treating them to avoid second contamination. Lower combustion efficiency and elevated fuel/feedstock ( F/ W) ratio for the FIBI led to the highest total emission factor of total-PAHs (38,400 μg kg −1). Lower total-PAH removal efficiencies of wet scrubber (WSB) (0.837–5.89%), cyclone (0.109–0.255%) and electrostatic precipitator (ESP) (0.032%) than those reported elsewhere resulted in high fraction in PAH contributions from the stack flue gases. Lower total-PAH emission factor was found for FLBI_A (2380 μg kg −1 biological sludge) with higher combustion efficiency compared to those for FLBI_B (11,500 μg kg −1) and FIBI (38,400 μg kg −1 biological sludge), implying that combustion efficiency plays a vital role in PAH emissions.

Polycyclic Aromatic Hydrocarbon Emission Profiles and Removal Efficiency by Electrostatic Precipitator and Wetfine Scrubber in an Iron Ore Sintering Plant

A monitoring campaign of polychlorinated dibenzo-p-dioxins and dibenzofurans, polyaromatic hydrocarbons (PAHs), and polychlorinated biphenyl was carried out in an Italian iron ore sintering plant by sampling the combustion gases at the electrostatic precipitator (ESP) outlet, at the Wetfine scrubber (WS) outlet, and by collecting the ESP dust. Few data are available on these micropollutants produced in iron ore sintering plants, particularly from Italian plants. This study investigates the PAH emission profiles and the removal efficiency of ESPs and WS. PAHs were determined at the stack, ESP outlet flue gases, and in ESP dust to characterize the emission profiles and the performance of the ESP and the WS for reducing PAH emission. The 11 PAHs monitored are listed in the Italian legislative decree 152/2006. The mean total PAH sum concentration in the stack flue gases is 3.96 μg/N · m3, in ESP outlet flue gases is 9.73 μg/N · m3, and in ESP dust is 0.53 μg/g. Regarding the emission profiles, the most abundant compound is benzo(b)fluoranthene, which has a relative low BaP toxic equivalency factors (TEF) value, followed by dibenzo(a,l)pyrene, which has a very high BaP(TEF) value. The emission profiles in ESP dust and in the flue gases after the ESP show some changes, whereas the fingerprint in ESP and stack flue gases is very similar. The removal efficiency of the ESP and of WS on the total PAH concentration is 5.2 and 59.5%, respectively.

Effective pollutant emission heights for atmospheric transport modelling based on real-world information

Emission data needed as input for the operation of atmospheric models should not only be spatially and temporally resolved. Another important feature is the effective emission height which significantly influences modelled concentration values. Unfortunately this information, which is especially relevant for large point sources, is usually not available and simple assumptions are often used in atmospheric models. As a contribution to improve knowledge on emission heights this paper provides typical default values for the driving parameters stack height and flue gas temperature, velocity and flow rate for different industrial sources. The results were derived from an analysis of the probably most comprehensive database of real-world stack information existing in Europe based on German industrial data. A bottom-up calculation of effective emission heights applying equations used for Gaussian dispersion models shows significant differences depending on source and air pollutant and compared to approaches currently used for atmospheric transport modelling.

Assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans contribution from different media to surrounding duck farms

Since the "Toxic Egg Event" broke out in central Taiwan, the possible sources of the high content of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in eggs have been a serious concern. In this study, the PCDD/F contents in different media (feed, soil and ambient air) were measured. Evaluation of the impact from electric arc furnace dust treatment plant (abbreviated as EAFDT plant), which is site-specific to the "Toxic Egg Event", on the duck total-PCDD/F daily intake was conducted by both Industrial Source Complex Short Term model (ISCST) and dry and wet deposition models. After different scenario simulations, the worst case was at farm A and at 200 g feed and 5 g soil for duck intake, and the highest PCDD/F contributions from the feed, original soil and stack flue gas were 44.92, 47.81, and 6.58%, respectively. Considering different uncertainty factors, such as the flow rate variation of stack flue gas and errors from modelling and measurement, the PCDD/F contribution fraction from the stack flue gas of EAFDT plant may increase up to twice as that for the worst case (6.58%) and become 13.2%, which was still much lower than that from the total contribution fraction (86.8%) of both feed and original soil. Fly ashes contained purposely in duck feed by the farmers was a potential major source for the duck daily intake. While the impact from EAFDT plant has been proven very minor, the PCDD/F content in the feed and soil, which was contaminated by illegal fly ash landfills, requires more attention.

Polychlorinated dibenzo- p-dioxin and dibenzofuran emissions from an industrial park clustered with metallurgical industries

Emissions of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) from an industrial park operated as Taiwan's center of metallurgical industries were investigated. The characteristics of mean PCDD/F I-TEQ concentrations, congener profiles and emission factors of each source were studied over samples of stack flue gases of individual sources. Different characteristics of congener profiles and large variations of emission factors of secondary aluminum smelters (ALSs) were observed. The mean emission factors of electric arc furnaces were comparable to those for ALSs and much greater than those of municipal solid waste incinerators and sinter plants, but still less than that of clinical waste incinerators. Annual PCDD/F emission contribution of each source was estimated, raising critical concerns over the overall PCDD/F emissions from metallurgical processes. The metallurgical industries altogether contributed ∼98.1% of the total annual emissions, while waste incinerators only 1.9%. The contributions by sinter plants and metallurgical industries to the total annual emissions of the Park were much higher than the corresponding national averages of Taiwan. The combined dioxin emissions from the entire metallurgical processes and their controls should be seriously envisaged by industrial parks devoted to metal productions.