Dust Treatment Research Articles

Effects of in vitro exposure to hay dust on the gene expression of chemokines and cell-surface receptors in primary bronchial epithelial cell cultures established from horses with chronic recurrent airway obstruction

To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or beta-glucan on chemokine and cell-surface receptor (CSR) gene expression in primary bronchial epithelial cell cultures (BECCs) established from healthy horses and horses with recurrent airway obstruction (RAO). BECCs established from bronchial biopsy specimens of 6 RAO-affected horses and 6 healthy horses. 5-day-old BECCs were treated with PBS solution, hay dust solutions, LPS, or beta-glucan for 6 or 24 hours. Gene expression of interleukin (IL)-8, chemokine (C-X-C motif) ligand 2 (CXCL2), IL-1beta, toll-like receptor 2, toll-like receptor 4, IL-1 receptor 1, and glyceraldehyde 3-phosphate dehydrogenase was measured with a kinetic PCR assay. Treatment with PBS solution for 6 or 24 hours was not associated with a significant difference in chemokine or CSR expression between BECCs from either group of horses. In all BECCs, treatment with hay dust or LPS for 6 hours increased IL-8, CXCL2, and IL-1beta gene expression > 3-fold; at 24 hours, only IL-1beta expression was upregulated by > 3-fold. In all BECCs, CSR gene expression was not increased following any treatment. With the exception of a 3.7-fold upregulation of CXCL2 in BECCs from RAO-affected horses (following 6-hour hay dust treatment), no differences in chemokine or CSR gene expression were detected between the 2 groups. At 24 hours, CXCL2 gene expression in all BECCs was downregulated. Epithelial CXCL2 upregulation in response to hay dust particulates may incite early airway neutrophilia in horses with RAO.

Crashα: coupling continuum and line radiative transfer

The detection of lya lines from local and distant objects has always been of great importance in astrophysics. It has been extensively used as indicator of redshift, as a measurement of the star formation activity of galaxies and as a probe of their internal structure. In the last few years an increasing interest has been devoted to the search of lya emitters (LAEs) at high redshift, which are expected to be characterized by a strong lya emission, but significantly attenuated by dust absorption. Emission of lya photons from high redshift sources has also an impact on the detectability of 21~cm line from neutral hydrogen in the Intergalactic Medium (IGM). This work is focused on the study, analysis and implementation of a new radiative transfer scheme (CRLya) which, for the first time in the literature, follows simultaneously the propagation of lya and ionizing radiation self-consistently. This allows to investigate the effects of evolving ionization configurations on the propagation of lya radiation and on the shaping of the line emerging from single objects. The implementation introduces the time evolution for lya photons (a feature commonly neglected in line radiative transfer codes) and, to reduce the computational time needed to follow each scattering, adopts a statistical approach to the lya treatment by making extensive use of pre-compiled tables. I find that the emerging spectra keep memory of the ionization history which generates a given ionization configuration of the gas and, to properly account for this effect, a self-consistent joint evolution of line and ionizing continuum radiation as implemented in CRLya is necessary. As next step, I implemented new features in CRLya: a new emission system, diffuse lya photons from recombination and treatment of dust. With a new test performed on a simulated galaxy at redshift z~10, I show the ability of the code to determine the variations of the lya radiation field while the gas in which it propagates is affected by the ionizing radiation emitted by the stars within the galaxy. In this test, the lya radiation is generated by both stars and recombining ionized gas. Finally I tackle the impact of lya photon scattering on the IGM temperature. This is an important issue since lya photons could be able to heat the IGM temperature above the CMB temperature and render the 21 cm line visible in emission. In the last Chapter, I discuss the implementation of the lya heating in \CRLya and I analyze how the temperature is modified by changing the most relevant physical parameters in the simulation.

Petroleum Coke Particle Size Effects on the Treatment of EAF Dust through Microwave Heating

EAF dusts were mixed with petroleum coke and irradiated together under microwave for a pyrometallurgical treatment. It was found that particle size of the reducing agent played an important role in affecting the reduction degree. Both zinc removal and metallization degree increased with the decreasing of the coke particle size. By changing both microwave time and carbon addition, optimal zinc removal at 99.23 % and metallization at 100 % can be achieved with 15 minutes microwave irradiation and 20 wt% carbon addition.

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.

Modeling water emission from low-mass protostellar envelopes

Within low-mass star formation, water vapor plays a key role in the chemistry and energy balance of the circumstellar material. The Herschel Space Observatory will open up the possibility to observe water lines originating from a wide range of excitation energies.Our aim is to simulate the emission of rotational water lines from envelopes characteristic of embedded low-mass protostars. A large number of parameters that influence the water line emission are explored: luminosity, density,density slope and water abundances.Both dust and water emission are modelled using full radiative transfer in spherical symmetry. The temperature profile is calculated for a given density profile. The H2O level populations and emission profiles are in turn computed with a non-LTE line code. The results are analyzed to determine the diagnostic value of different lines, and are compared with existing observations. Lines can be categorized in: (i) optically thick lines, including ground-state lines, mostly sensitive to the cold outer part; (ii) highly excited (E_u>200-250 K) optically thin lines sensitive to the abundance in the hot inner part; and (iii) lines which vary from optically thick to thin depending on the abundances. Dust influences the emission of water significantly by becoming optically thick at the higher frequencies, and by pumping optically thin lines. A good physical model of a source, including a correct treatment of dust, is a prerequisite to infer the water abundance structure and possible jumps at the evaporation temperature from observations. The inner warm (T>100 K) envelope can be probed byhighly-excited lines, while a combination of excited and spectrally resolved ground state lines probes the outer envelope. Observations of H218O lines, although weak, provide even stronger constraints on abundances.

Comparative Absorption and Bioaccumulation of Polybrominated Diphenyl Ethers following Ingestion via Dust and Oil in Male Rats

Household dust has been implicated as a major source of polybrominated diphenyl ether (PBDE) exposure in humans. This finding has important implications for young children, who tend to ingest more dust than adults and may be more susceptible to some of the putative developmental effects of PBDEs. Absorption parameters of PBDEs from ingested dust are unknown; therefore, the objectives of this study were to determine and to compare the uptake of PBDEs from either household dust (NIST Standard Reference Material 2585) or a corn oil solution. Male rats were administered dust or corn oil doses at 1 or 6 microg of PBDEs kg(-1) body wt in the diet for 21 days (n = 4 rats per group). The concentrations of 15 PBDEs were measured in adipose tissue and liver from each treatment group and showed that bioconcentration was congener dependent, but for the majority of congeners, the concentrations did not differ with either dose level or dose vehicle. Hepatic Cyp2b1 and 2b2 mRNA expression increased in rats receiving the higher PBDE doses, suggesting potential effects on metabolic activity. Retention of PBDEs in tissues ranged from <5% of the dose for BDE-209 to 70% for BDEs-47, 100, and 153 but generally did not differ between the high dust and high oil treatment groups. Excretion via the feces was significantly lower in the high oil dosed rats suggesting differences in absorption, excretion, and/or metabolism. The present study shows that PBDEs in dust are readily bioavailable and are biologically active, as indicated by increased transcription of hepatic enzymes.

EVALUATION OF OPTIONS FOR METALS RECOVERY FROM ALTASTEEL EAF DUST

Several process options for the treatment of Altasteel electric arc furnace dust (9.4% Zn, 31.9% Fe) are discussed including hot acid leaching, Na2CO3 roasting, Waelz kiln processing and a modified Waelz kiln process using more oxidizing roasting conditions and acid leaching to recover zinc from the residue. Elemental deportments and their implications on possible process flowsheets are discussed and flowsheets are developed to allow comparisons among the various processes based on metal recoveries, residue stability, reagent consumption, operating temperatures and potential removal of deleterious minor elements.Of the processes discussed, the modified Waelz kiln process appears to be the best option in terms of process simplicity and the volume and stability of the residue produced. The trade-offs for this increase in residue stability are higher acid consumptions during leaching and possibly higher coal costs during roasting compared with the more traditional Waelz kiln processing.On discute de plusieurs options de procédé pour le traitement de la poussière du four électrique à arc d’Altasteel (9.4% Zn, 31.9% Fe), incluant la lixiviation à l’acide chaud, la calcination au Na2CO3, le traitement au séchoir de Waelz et un procédé au séchoir de Waelz modifié utilisant des conditions de calcination plus oxydantes ainsi que la lixiviation à l’acide, pour récupérer le zinc du résidu. On discute des points élémentaires et de leurs implications sur les schémas de procédés potentiels et l’on développe ces schémas afin de comparer les divers procédés en se basant sur la récupération de métal, sur la stabilité du résidu, sur la consommation de réactif, sur les températures de service et sur l’enlèvement potentiel des éléments mineurs nuisibles.Parmi les procédés discutés, le procédé du séchoir deWaelz modifié semble la meilleure option en ce qui a trait à la simplicité du procédé et au volume et à la stabilité du résidu produit. Les compromis de cette augmentation de la stabilité du résidu sont une consommation plus élevée d’acide lors de la lixiviation et possiblement des coûts plus élevés de charbon lors de la calcination par rapport au traitement plus traditionnel au séchoir de Waelz.

Insecticidal effect of spinosad dust, in combination with diatomaceous earth, against two stored-grain beetle species

Laboratory bioassays were carried out to determine the efficacy of spinosad applied alone or combined with the diatomaceous earth (DE) SilicoSec against adult rice weevils, Sitophilus oryzae and confused flour beetles, Tribolium confusum. Efficacy was assessed on wheat and maize at three dosages of spinosad dust formulation (corresponding to 0.0625, 0.1875 and 0.625 ppm of active ingredient [AI] for S. oryzae and to 0.1875, 0.625 and 1.25 ppm of AI for T. confusum), alone or combined with SilicoSec at 150 ppm for S. oryzae and 250 ppm for T. confusum. The mortality of S. oryzae exposed for 14 d on wheat treated with spinosad ranged between 83% and 100%. Conversely, the mortality of S. oryzae on maize treated with DE or on maize treated with lower doses of spinosad dust did not exceed 19% and was only 59% on maize with the highest spinosad dust treatment. Generally, the presence of SilicoSec combined with spinosad did not significantly increase S. oryzae mortality compared with spinosad alone. For T. confusum, mortality on both commodities was lower than for S. oryzae. After 14 d of exposure on wheat, mortality was 14% at the highest dose of spinosad, but increased to 33% in the presence of DE. Similar results were also obtained for T. confusum exposed on treated maize, which indicated a joint action between spinosad and DE. In the case of S. oryzae, the inclusion of DE reduced progeny production in comparison with spinosad alone. Progeny production of T. confusum was relatively low in all treatments, compared to progeny production of S. oryzae. The results of the study show the potential of combination treatments of spinosad dust and DE, but efficacy varies with the target insect species and commodity.

New EAF Dust Treatment Process with the Aid of Strong Magnetic Field

A new EAF dust treatment process named as “Lime Addition and Magnetic Separation Process (LAMS Process)” has been proposed to recover zinc oxide from the dust and to use solid residue as a flux for steel refining. The LAMS Process consists of the reaction of EAF dust with CaO followed by the adequate crushing and high gradient magnetic separation. The basic principle of this process has been established by revealing the phase equilibria in the CaO–Fe2O3–ZnO system where Ca2Fe2O5 can be in equilibrium with pure ZnO rather than ZnFe2O4, which is the major component of EAF dust, at higher CaO region. The conversion of zinc ferrite in EAF dust to ZnO and Ca2Fe2O5 has been experimentally demonstrated by heating the dust with double molar amount of CaO at 1173 and 1373 K. It has also been demonstrated that the formed ZnO and Ca2Fe2O5 can be separated by the strong magnetic field. Therefore, it may be possible to recover ZnO from EAF dust without the carbothermic reduction like Waelz process.

Substance Flow Analysis of Zinc Associated with Iron and Steel Cycle in Japan, and Environmental Assessment of EAF Dust Recycling Process

Japanese zinc production in 2005 was 6.75×105 t, and domestic demand of zinc was 4.82×105 t. The main use of metallic zinc is in the surface coating of steel and the metal accounts for 62.8% of the domestic demand. The purposes of this study are as follows: (1) to identify the material flow of zinc associated with steel production, and (2) to estimate the environmental effects (energy consumption and CO2 emission reduction) of some intermediate dust treatment processes.The major conclusions are (a) in Japan, 6.16×106 t of blast furnace/converter dust was generated in 2000, and this product contained 2.20×104 t-Zn. 0.433×106 t of EAF dust was generated and this dust contained 8.86×104 t-Zn, and (b) 9.57 MJ of energy is required for producing 1 kg of zinc oxide by the Waelz process using EAF dust, and the estimated amount of CO2 emission in this process is 1.49 kg-CO2. On the other hand, if the LAMS process proposed by the authors is employed, it is estimated that there will be a reduction of 1.70 MJ in energy consumption and a reduction of 0.14 kg-CO2 in CO2 emissions.

Basic Consideration on EAF Dust Treatment Using Hydrometallurgical Processes

Electric Arc Furnace (EAF) dust, defined as special industrial waste in Japan, is treated through pyrometallurgical processes in which crude ZnO powder is recovered. An on-site type process, however, is desired to reduce treatment cost and cost of transportation of the dust. A hydrometallurgical process is considered to be suitable for such an on-site treatment. Although many EAF dust treatment processes by hydrometallurgical method have been proposed, most of them have not been commercialized in Japan. A short review of hydrometallurgical processes for EAF dust was done and a new hydrometallurgical process for EAF dust was proposed in this study. Nitric acid solution is used for the extraction of ZnO from the dust. Some characteristics of the process are as follows: (1) Recovery of Zn from zinc ferrite in EAF dust is the target, while the dissolution of Fe is limited by controlling the pH of the solution. (2) Zn is recovered as metallic Zn by electrowinning from the solution and nitric acid is regenerated in the anode.

The effect of salting with magnesium chloride on the concentration of particular matter in a road tunnel

This work presents an analysis of the effect of dust treatment with a magnesium chloride solution on the concentration of airborne particulate matter inside a road tunnel. During the winter 2004/2005, the road inside the tunnel of Strømsås was salted 43 times with magnesium chloride solution, of which 27 times with the amount 20 g m - 2 and 16 with 40 g m - 2 . In addition, the road was swept 11 times and washed twice. Simultaneously, one recorded the concentration of PM 10 and PM 2.5 hourly. The model used in the analysis is a generalised additive model (GAM) on log-scale, having traffic counts, diverse meteorological conditions and the pollution reducing actions as predictor variables. The analysis revealed no clear effect from sweeping and washing. The impact of the dust binding medium on the concentrations of particulate matter is, however, clearly propitious. As one would expect, it is largest immediately after applying the magnesium chloride, and diminishes steadily afterwards. The duration of the effect is estimated to 10 days, but with a rather large uncertainty (95% confidence intervals between 3 and 16 days). We estimated an effect (reduced pollution level) of 70 % on the concentration of the coarse particles PM 10 – PM 2.5 and 56 % on the concentration of PM 10 . The estimated effect on the fine particles PM 2.5 is a modest 17 % , and barely significant.

The cycle of interstellar dust in galaxies of different morphological types

Aims. We used chemical evolution models for galaxies of different morphological type to perform a detailed study of the evolution of the cosmic dust properties in different environments: the solar neighbourhood, elliptical galaxies and dwarf irregular galaxies. Thanks to the uptodate observations available in the solar vicinity, we intend to study the effects of dust in the chemical evolution of different types of galaxies and, at the same time, to refine investigation of the parameter space to satisfactorily fine-tune the parameters in our study. Methods. We have considered dust production from low and intermediate mass stars, supernovae Ia, supernovae II, and both dust destruction and dust accretion processes in a detailed model of chemical evolution for the solar vicinity. Then, by means of the same dust prescriptions, but adopting different galactic models (different star formation histories and the presence of galactic winds), we extended our study to ellipticals and dwarf irregular galaxies. In all these systems, dust evolution was calculated by means of chemical evolution models that relax the instantaneous recycling approximation and already reproduce the main features of the various galaxies. Results. We have investigated how the assumption of different star formation histories affects the dust production rates, dust depletion, the dust accretion, and destruction rates. We predict dust-to-gas and dust-to-metal ratios in very good agreement with those observed in the solar vicinity. We show how the inclusion of the dust treatment is helpful in solving the so-called Fe discrepancy, as observed in the hot gaseous halos of local ellipticals, and in reproducing the chemical abundances observed in the Lyman Break Galaxies. Finally, our new models can be very useful in future detailed spectro-photometric studies of galaxies.

Investigation of stabilization/solidification for treatment of electric arc furnace dust: Dynamic leaching of monolithic specimens

Diffusion-controlled leaching of heavy metals (Cr, Ni, Pb and Zn) from electric arc furnace dust treated with ground granulated blast furnace slag (GGBFS) and with ordinary Portland cement (OPC) was evaluated. Monolithic specimens were evaluated under dynamic leaching conditions for 84 days with periodic leachant renewal. The influence of leaching time, nature of the leachant, binder type and the water/solid ratio of the monoliths were investigated. Results obtained showed both binders can immobilize heavy metals in the monoliths under dynamic leaching conditions, with cumulative quantity of leached metal under 0.138 mg (Cr). Alkaline leachant increased metal release from specimens and reducing the water/solid ratio of the monolith allowed for a decrease in the cumulative mass of metals leached. Chemical and mineralogical characterizations indicated that the metals were evenly distributed throughout the specimens for both binders. Decalcification was observed on the OPC monolith border following leaching. This decrease in Ca corresponded to an altered zone (20 μm), identified by scanning electron microscopy. The GGBFS sample did not show an altered zone.

Assessing the Predictive Power of Galaxy Formation Models: A Comparison of Predicted and Observed Rest-Frame Optical Luminosity Functions at [FORMULA][F]2.0≤z≤3.3[/F][/FORMULA

Recent galaxy formation models successfully reproduce the local luminosity function (LF) of galaxies by invoking mechanisms to suppress star formation in low- and high-mass galaxies. As these models are optimized to fit the LF at low redshift, a crucial question is how well they predict the LF at earlier times. Here we compare recently measured rest-frame V-band LFs of galaxies at redshifts 2.0<z<3.3 to predictions of semianalytic models by De Lucia & Blaizot and Bower et al. and hydrodynamic simulations by Dave et al.. The models succeed for some luminosity and redshift ranges and fail for others. A notable success is that the Bower et al. model provides a good match to the observed LF at z~3. However, all models predict an increase with time of the rest-frame V-band luminosity density, whereas the observations show a decrease. The models also have difficulty matching the observed rest-frame colors of galaxies. In all models the luminosity density of red galaxies increases sharply from z~3 to z~2.2, whereas it is approximately constant in the observations. Conversely, in the models the luminosity density of blue galaxies is approximately constant, whereas it decreases in the observations. These discrepancies cannot be entirely remedied by changing the treatment of dust and suggest that current models do not yet provide a complete description of galaxy formation and evolution since z~3.

A novel method to enhance polychlorinated dibenzo- p-dioxins and dibenzofurans removal by adding bio-solution in EAF dust treatment plant

In order to understand the effect of different amounts of powder-activated carbon (PAC) injection and bio-solution (NOE-7F) addition on the removal efficiencies of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) in a fly ash treatment plant with Waelz rotary kiln process, the PCDD/F concentrations in the stack flue gasses were measured and discussed. In the amount of 20, 40 and 50 kg/h PAC injection, the removal efficiencies of PCDD/Fs in the stack flue gas were 86, 96 and 97%, respectively. While adding more amounts of PAC did enhance the removal efficiencies, the reduction fractions of low chlorinated PCDD/F congeners were much higher than those of highly chlorinated PCDD/F congeners. Particularly, a lower amount of PAC injection (20 kg/h), not only cannot remove highly chlorinated PCDD/Fs, but also the carbon surface of the PAC can act as a precursor for the formation promotion of highly chlorinated PCDD/F congeners. The addition of NOE-7F in the raw materials had the dechlorination effect on the PCDD/F removal and mainly inhibited highly chlorinated PCDD/F formation. The combination of both PAC injection and NOE-7F addition has a high potential for practical application.

Direct observations of the atmospheric processing of Asian mineral dust

Abstract. The accumulation of secondary acids and ammonium on individual mineral dust particles during ACE-Asia has been measured with an online single-particle mass spectrometer, the ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles correlate with air masses from different source regions. The uptake of secondary acids depended on the individual dust particle mineralogy; high amounts of nitrate accumulated on calcium-rich dust while high amounts of sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate dust is a possible explanation for this enrichment of sulphate, which has important consequences for the fertilization of remote oceans by soluble iron. This study shows the segregation of sulphate from nitrate and chloride in individual aged dust particles for the first time. A transport and aging timeline provides an explanation for the observed segregation. Our data suggests that sulphate became mixed with the dust first. This implies that the transport pathway is more important than the reaction kinetics in determining which species accumulate on mineral dust. Early in the study, dust particles in volcanically influenced air masses were mixed predominately with sulphate. Dust mixed with chloride then dominated over sulphate and nitrate when a major dust front reached the R. V. Ronald Brown. We hypothesize that the rapid increase in chloride on dust was due to mixing with HCl(g) released from acidified sea salt particles induced by heterogeneous reaction with volcanic SO2(g), prior to the arrival of the dust front. The amount of ammonium mixed with dust correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent reports that they exist as external mixtures. The size distribution of the mixing state of dust with these secondary species validates previous mechanisms of the atmospheric processing of dust and generally agrees with simulated aerosol chemistry from the STEM-2K3 model. This series of novel results has important implications for improving the treatment of dust in global chemistry models and highlights a number of key processes that merit further investigation through laboratory and field studies.

リサイクリング・プロセスと操業 曹鉄メタル（株）における製鋼煙灰処理

Sotetsu Metal Co., Ltd. was established in 1974 and started operation of Waelz kiln plant for treatment of EAF dust. In 1996, Sotetsu plant installed two Waelz kilns in series. At present, Sotetsu plant treats 70,000 tons of dust and produces 24,000 tons of crude zinc oxide and then 18,000 tons of high grade zinc oxide per annum. The chemical composition of the high grade zinc oxide is 78wt%Zn, 1.1wt%Fe, 0.02wt%Pd,

リサイクリング・プロセスと操業 四阪工場における製鋼煙灰処理

リサイクリング・プロセスと操業 四阪工場における製鋼煙灰処理

Integrated environmental assessment and pollution prevention in Vietnam: the case of anthracite production

Using the concept of life cycle analysis, the whole life cycle of anthracite production in Vietnam was assessed and the environmental “hot-spots” were identified. These include (i) dust pollution at coal transfer points or piles in storage; (ii) noise pollution resulting from the usage of heavy equipment, and (iii) high volume of acid and turbid mine water discharged into the environment. Pollution prevention and treatment options were identified and discussed in this study which consists of wet treatment of dust, planning, collection and treatment of mine water, planting of trees for dust and noise reduction as well as minimization of erosion. Some recommendations are made for pollution abatement from coal production and improvement of anthracite production in the region.