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Query: UMLS:C0205700 (ash)
 15,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bottom and fly ash collected from automobile shredder residue (ASR) incinerator have been characterized in terms of particle size, compositions, and heavy metal leaching by the standard TCLP method. Two alternative methods were also examined for the treatment of heavy metals in ASR incinerator ash from the aspect of recycling into construction or lightweight aggregate material. It was remarkable that the concentration of Cu was very high compared to common MSWI bottom and fly ash, which was probably originated from copper wires contained in ASR. As a whole, the results of characterization of ASR fly ash were in good agreement with common MSWI fly ash in terms of particle size, pH, and water-soluble compounds. It was clearly found that heavy metals could be removed thoroughly or partly from ASR fly ash through acid washing with dilute HCl solution so that the remaining fly ash could be landfilled or used as construction material. It was also found that the amount of heavy metal leachability of lightweight aggregate pellet prepared with ASR incineration ash could be significantly decreased so that the application of it to lightweight aggregate would be possible without pre-treatment for the removal of heavy metals.
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PMID:Characteristics and heavy metal leaching of ash generated from incineration of automobile shredder residue. 1731 85

Waste printed circuit boards containing brominated flame retardants were pyrolyzed in a high-temperature melting system to observe the formation behaviors of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs). In this study, the results showed that the formation of PBDD/ Fs during pyrolysis can be destroyed under controlled primary combustion conditions. There were two significant factors that influenced the extent of PBDD/F formation. The first factor was temperature. The results showed that, both the total PBDD/F content in the bottom ash and the total PBDD/F emission factor from the flue gas decrease by approximately 50% with an increase of the pyrolysis temperature from 850 to 1200 degrees C. The second factor was the addition of CaO. The possible mechanism involves the reaction between CaO and HBr to form the solid-phase product CaBr2. Thus, the addition of CaO is effective in adsorbing HBr and results in the inhibition of PBDD/F synthesis by more than 90% and further prevents the acid gases (HCl and HBr) that corrode the equipment. In conclusion, due to the persistence and toxicity of PBDD/Fs, a combined regulation for controlling both PCDD/Fs and PBDD/Fs is of great importance for environmental protection issues.
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PMID:Inhibition of polybrominated dibenzo-p-dioxin and dibenzofuran formation from the pyrolysis of printed circuit boards. 1732 9

The combustion of wastes has very significant benefits in reducing the volume of waste materials and producing energy. However, combustion processes produce emissions, which must be below the Best Practical Means (BPM) specified legislative limits. Several wastes, such as tires and meat meal, have been successfully combusted in cement kilns, up to 20% w/w, while retaining emission standards well below legislative limits. In the case of municipal solid waste (MSW) the introduction of large amounts of MSW into cement kilns is not practical because the additional kiln volume required is too great, the large amounts of ash generated will affect the cement clinker quality, and it would be difficult to sustain the required very high clinkering temperature of 1500 degrees C with large quantities of low calorific value MSW. A completely novel process, termed the Co-Co process, has been developed, integrating MSW combustion in a synergistic fashion with the cement production. This process is based on combining the cement "front-end" calcination reaction and incorporating it with a high temperature, at 1200 degrees C, combustion process, providing a giant acid gas scrubber. A pilot plant was designed, constructed, and operated to demonstrate the benefits of the Co-Co process. The pilot plant achieved emissions minimization: dioxins were typically 0.5-1% of the European BPM limits, HCl, SOx, NOx, and particulates were 15, 10, 20, and 25% of BPM limits, respectively. Heavy metals were typically below 25% of BPM limit values.
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PMID:Minimizing dioxin emissions from integrated MSW thermal treatment. 1741 Jul 97

A novel process, termed the co-combustion process, has been developed and designed to utilise the thermal treatment of municipal solid waste (MSW) in cement clinker production and reduce PCDD/PCDF emissions. To test the conceptual design; detailed engineering design of the process and equipment was performed and a pilot plant was constructed to treat up to 40 tonnes MSW per day. The novel process features included several units external to the main traditional cement rotary kiln: an external calcinations unit in which the hot gas calcined the limestone thus making significant energy savings for this chemical reaction; the lime generated was used in a second chamber to act as a giant acid gas scrubber to remove SOx and particularly HCl (a source of chloride); an external rotary kiln and secondary combustion unit capable of producing a hot gas at 1200 degrees C; a gas cooler to simulate a boiler turbogenerator set for electricity generation; the incorporation of some of the bottom ash, calcined lime and dust collector solids into the cement clinker. A PCDD/PCDF inventory has been completed for the entire process and measured PCDD/PCDF emissions were 0.001 ng I-TEQ/Nm(3) on average which is 1% of the best practical means [Hong Kong Environmental Protection Department, 2001. A guidance note on the best practicable means for incinerators (municipal waste incineration), BPM12/1] MSW incineration emission limit values.
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PMID:PCDD/PCDF reduction by the co-combustion process. 1770 44

Chemical fingerprint techniques are frequently applied to airborne volcanic eruption products, so-called tephra, such as ash and pumice for archeological and geoscientific purposes. However, in some cases, a meaningful interpretation of the results is complicated by superficial contaminations. Therefore, this situation was simulated by the use of powdered rhyolitic pumice to investigate its capability to adsorb several ions from aqueous solutions. Using neutron activation analysis, adsorption could be proven for Cr(3+), Cr(2)O(7)(2-) (dichromate), Fe(3+), Co(2+), HAsO(4)(2-) (hydrogen arsenate), Rb(+), Sr(2+), Cs(+), Ba(2+), La(3+), Ce(3+), Ce(4+), Sm(3+), Th(4+) and UO(2)(2+), which is a clear evidence for the interaction of those ions with the volcanic glass. In our experiments, pumice powder showed the ability to adsorb ions in the range from 1.8 mg kg(-1) (in case of HAsO(4)(2-)) to 5.8 wt% (in case of Fe(3+)). Adsorption is probably due to ion-exchange reactions. It could also be shown that a few ions are not adsorbed in detectable quantities: Na(+), K(+), Fe(2+), Zn(2+) and Nd(3+). The knowledge about adsorption of ions enables us not only to examine the possible influence of contaminations where chemical fingerprinting methods are applied to volcanic material for archaeometry, but it also suggests the technical application of pumiceous materials for technical purposes, like water purification or as an adsorbent in the final storage of nuclear waste. In another series of INAA supported experiments, the influence of chemicals like ascorbic acid, acetic acid, HCl, HF, HNO(3), H(2)O, H(2)O(2), H(3)PO(4), H(2)SO(4), NaOH and NH(3) on the bulk composition of pumice powder was investigated-resulting in no detectable change. We conclude that superficially contaminated tephra can be washed in diluted HF to remove contaminations without influencing the chemical fingerprint.
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PMID:Adsorption of ions onto high silica volcanic glass. 1771 93

Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) analysis has been applied to the determination of tin in a fly ash sample supplied by the EC Joint Research Centre (Ispra, Italy). The proposed procedure includes the silica gel/phosphoric acid technique for tin thermal ionisation activation and a strict heating protocol for isotope ratio measurements. Instrumental mass discrimination factor has been previously determined measuring a natural tin standard solution. Spike solution has been prepared from 112Sn-enriched metal and quantified by reverse isotope dilution analysis. Two sample aliquots were spiked and tin was extracted with 4.5M HCl during 25 min ultrasound exposure time. Due to the complex matrix of this fly ash material, a two-step purification stage using ion-exchange chromatography was required prior TIMS analysis. Obtained results for the two sample-spike blends (10.11+/-0.55 and 10.50+/-0.64 micromol g(-1)) are comparable, both value and uncertainty. Also a good reproducibility is observed between measurements. The proposed ID-TIMS procedure, as a primary method and due to the lack of fly ash reference materials certified for tin content, can be used to validate more routine methodologies applied to tin determination in this kind of samples.
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PMID:Isotope dilution-thermal ionisation mass spectrometric analysis for tin in a fly ash material. 1772 49

In the report "Mutagenicity of fly ash particles in Paramecium" by J. Smith-Sonneborn et al. (9 Jan., p. 180), Tables 1 and 2 are printed incorrectly. Significance lines are missing from both tables and "uninduced" should read "induced" in the sixth, eighth, and ninth entries of the first column in Table 1. The tables are reprinted below as they should have appeared. Table 1. Mutagenic effect of fly ash and heat-treated fly ash in Paramecium. Values not connected by the same line are significantly different from each other (Wilcoxon matched-pairs signed-ranks test, alpha = .05). The data from six experiments were pooled since the control values for autogamous progeny were not significantly different. Cerophyl is the ryegrass extract used for cultivation of Paramecium. Induced S-9 is the Ames liver microsome fraction from rats receiving Arochlor 1254 (polychlorinated biphenyl) to activate the enzymes for conversion of promutagens to mutagenic form; uninduced S-9 is from rats receiving corn oil only (the vehicle for the Arochlor). Glass beads (1 to 3 ,microm) suspended in either induced or uninduced S-9 were used as a negative control for nonnutritive particles. Kaolinite was also used in one experiment, and the results were the same as those for the glass beads. Benzo[a]pyrene was the positive control for mutagenicity requiring induced S-9. The initial concentration of suspended fly ash was 535 ,microg/ml. The average number of affected progeny from treated parent cells was 20 percent higher than the average number of affected control progeny. Since one mutation would theoretically yield only 4 affected progeny in 16 autogamous progeny from a treated parent cell (6), the percentages, though low, reflect significant damage. [See table in the PDF file] Table 2. Mutagenicity of heat-treated fly ash extracted with HCl or DMSO. Values not connected by the same line are significantly different from each other (pairwise comparisons of proportions, P < .05). The concentration of fly ash particles suspended in uninduced S-9 was 1068 ,ug/ml. The higher than usual value for mutagenicity in the controls can be attributed to the considerable age of the clone used here [micronuclear damage increases with age (12)]. [See table in the PDF file].
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PMID:Erratum. 1777 34

Carbon-enriched fractions have been obtained from two coal fly ash (FA) samples. The FA came from two pulverized-coal fired power stations (Lada and Escucha, Spain) and were collected from baghouse filters. Sieving was used to obtain carbon-enriched fractions, which were further subjected to two beneficiation processes: acid demineralization using HCl and HF, and oil agglomeration using soya oil-water. Yield in weight after sieving, unburned carbon content, and several physicochemical characteristics of the obtained fractions were used to compare the performance of the beneficiation methods. Low carbon concentration was obtained by sieving, particularly in the case of Escucha FA. However, after acid demineralization or oil agglomeration, fractions containing unburned carbon in a range of 63% to 68% were obtained. These fractions showed differences in mineral phase composition and distribution depending on the FA and on the beneficiation method used. The textural properties of the obtained fractions varied as a function of their carbon content and the beneficiation method used. However, no significant differences in morphology of the carbonaceous particles were found.
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PMID:Preparation and characterization of carbon-enriched coal fly ash. 1782 88

Earlier estimates of the chlorine emission from volcanoes, based upon evaluations of the preeruption magmatic chlorine content, are too low for some explosive volcanoes by a factor of 20 to 40 or more. Degassing of ash erupted during 1976 by Augustine Volcano in Alaska released 525 x 10(6) kilograms of chlorine (+/- 40 percent), of which 82 x 10(6) to 175 x 10(6) kilograms may have been ejected into the stratosphere as hydrogen chloride. This stratospheric contribution is equivalent to 17 to 36 percent of the 1975 world industrial production of chlorine in fluorocarbons.
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PMID:Volcanic contribution of chlorine to the stratosphere: more significant to ozone than previously estimated? 1783 67

This study investigates the adsorption behavior of Reactive Black 5 (RB) and Reactive Yellow 176 (RY) from aqueous solution on coal fly ash (FA-CO), HCl-treated coal fly ash (TFA-HCl), and biomass fly ash (FA-BM). In preliminary study, the FA-BM showed the greatest dye adsorption capacity of both dyes, compared to FA-CO and TFA-HCl. Hence only for the FA-BM, the effects of various experiment parameters (e.g. solution pH, ionic strength, initial dye concentration, contact time) were spectrophotometrically determined. At the final pH of 8.1-8.5, the adsorption capacity of both dyes on the FA-BM was maximum and decreased above or below this pH. A positive effect of salt addition on the dye adsorption capacity was observed. The adsorption capacity of dye on the FA-BM increased with increasing C0. The equilibrium data of both dyes on the FA-BM were fitted to both Langmuir and Freundlich isotherms, but the experimental data of the RB was found to be little better fitted by the Langmuir model. The sorption data was good fit with the pseudo-second-order kinetic model. These results indicate that biomass fly ash is an interesting alternative for dye removal from the wastewater.
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PMID:Sorption of reactive dye from aqueous solution on biomass fly ash. 1798 94


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