| 1. |
- Arm, Maria
(författare)
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Self-cementing properties of crushed demolished concrete in unbound layers : results from triaxial tests and field tests
- 2001
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Ingår i: Waste Management. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0956-053X .- 1879-2456. ; 21:3, s. 235-239
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Tidskriftsartikel (refereegranskat)abstract
- A 2-year study is underway to evaluate the expected growth in stiffness in layers of crushed concrete from demolished structures. This growth is said to be a result of self-cementing properties. The study consists of repeated load triaxial tests on manufactured specimens after different storing time together with falling weight deflectometer, FWD, measurements on test sections. Results so far show a clear increase with time in resilient modulus and in back-calculated layer modulus for all concrete materials. The increase is the largest in the first months and then diminishes. The field measurements show a more considerable growth in stiffness than the laboratory tests, with a doubled value two years after construction. Comparative investigations on natural aggregates, mostly crushed granite do not show any growth in stiffness, neither in the laboratory nor in the field. Consequences for the choice of design modulus are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.
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| 2. |
- Ecke, Holger
(författare)
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Sequestration of metals in carbonated municipal solid waste incineration (MSWI) fly ash
- 2003
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 631-640
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Tidskriftsartikel (refereegranskat)abstract
- Waste management is in need of a reliable and economical treatment method for metals in fly ashes from municipal solid waste incineration (MSWI). However, no state-of-the-art technique has gained wide acceptance yet. This paper is a synthesis of five elsewhere published investigations covering a project which aimed to assess the possibilities and limitations of adding carbon dioxide (CO2) to fly ash as a stabilization method. Carbonation factors that were studied are the partial pressure of carbon dioxide (CO2), the addition of water, the temperature, and the reaction time. Laboratory experiments were performed applying methods such as factorial experimental design, thermal analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and leaching assays including pHstat titration and sequential extraction. Leaching data were verified and complemented using chemical equilibrium calculations. Data evaluation was performed by means of multivariate statistics such as multiple linear regression, principal component analysis (PCA), and partial least squares (PLS) modeling. It was found that carbonation is a good prospect for a stabilization technique especially with respect to the major pollutants lead (Pb) and zinc (Zn). Their mobility decreased with increasing factor levels. Dominating factors were the partial pressure of CO2 and the reaction time, while temperature and the addition of water were of minor influence. However, the treatment caused a mobilization of cadmium (Cd), requiring further research on possible countermeasures such as metal demobilization through enhanced silicate formation.
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| 3. |
- Jonsson, Susanne, 1965-, et al.
(författare)
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Transformation of phthalates in young landfill cells
- 2003
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 641-651
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Tidskriftsartikel (refereegranskat)abstract
- Phthalic acid diesters are additives in a variety of materials that can end up in landfills. Leachates from a series of full-scale young landfill cells were analysed over time for dimethyl, diethyl, dibutyl, butylbenzyl, and di(2-ethylhexyl) phthalate (respectively designated DMP, DEP, DBP, BBP, and DEHP), and their corresponding monoesters monomethyl, monoethyl, monobutyl, monobenzyl, and mono(2-ethylhexyl) phthalate (MMP, MEP, MbutP, MbenzP, and MEHP, respectively), as well as o-phthalic acid (PA). One landfill cell was created in each of three consecutive years by deposition of the same type of waste in July and August. The pH, volatile fatty acids (VFAs), and total organic carbon (TOC) were measured to characterise development of the degradation phases in three landfill cells, which revealed early acidogenic to initial methanogenic stages. Analysis of the phthalate compounds showed that observed concentrations of the degradation products were below the detection limit in the acidogenic leachates but exceeded concentrations of their corresponding diesters in leachates from cells in the initial methanogenic phase. Maximum and average concentrations of phthalic acid were 50 and 23 mg/l, respectively, and the corresponding values for the other phthalates were 430 and 27 ╡g/l. The concentrations of all phthalates decreased during the establishment of stable methanogenic conditions. ⌐ 2003 Elsevier Ltd. All rights reserved.
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| 4. |
- Kylefors, Katarina, et al.
(författare)
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A comparison of small scale pilot-scale and large-scale tests for predicting leaching behaviour of landfilled wastes
- 2003
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:1, s. 45-59
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Tidskriftsartikel (refereegranskat)abstract
- Landfills generate emissions over long periods, often longer than a lifetime. The longest lasting emission is leachate. In order to estimate the future requirements for leachate treatment, different kinds of leaching tests may be applied. In this paper, shaking leaching tests (SLT), landfill-simulator leaching tests and a field-cell leaching test performed with ash, municipal solid waste (MSW) and MSW+ash are evaluated. The tests are compared and the factors influencing leaching are identified and discussed. The factors are: liquid to solid (L/S) ratio, water withdrawal, recirculation rate, presence or absence of biological processes, size of particles, duration of experiment, temperature and pre-treatment of the waste. The presence of biological processes has the greatest impact on leaching and is the main reason why SLT is less useful for long-term predictions. The landfill simulator tests were found to be useful for several different kinds of predictions. However, they are not reliable for predicting the L/S required for reaching a certain concentration. The possibilities for reliable long-term predictions would be facilitated by a better knowledge of the influence of various factors on leaching. Such an increased knowledge would make it possible to enhance waste stabilisation in leaching tests as well as in full-scale landfills.
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| 5. |
- Lind, B.B., et al.
(författare)
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Environmental impact of ferrochrome slag in road construction
- 2001
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 21:3, s. 255-264
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analysed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials. Copyright (C) 2001 Elsevier Science Ltd.Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analyzed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials.
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| 6. |
- Menad, Nourreddine, et al.
(författare)
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Study of the presence of fluorine in the recycled fractions during carbothermal treatment of EAF dust
- 2003
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:6, s. 483-491
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Tidskriftsartikel (refereegranskat)abstract
- Carbothermal treatment tests of electric arc furnace dusts (EAFD) using the Waelz kiln process were carried out in pilot-scale for the production of zinc oxide. The association of halides in the EAFD, and the recycled products, such as zinc oxide fumes and high-grade iron contents fractions were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. XRD reveals the presence of chlorine and fluorine in the dusts in the form of KCl, NaCl and CaF2. An ultra-pure fraction of zinc was obtained after the Double Leaching Waelz Oxide (DLWO) process was performed on the zinc oxide fumes. The halide contents were reduced to approximately 100 ppm Cl and 700 ppm F. The rest of these elements are in the form of CaF2. About 65% F is volatilised as lead and zinc fluorides, 15% is expected in the magnetic fractions and 20% in non-magnetic fractions as CaF2 and MnF2, respectively.
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| 7. |
- Shen, Huiting, et al.
(författare)
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An overview of recovery of metals from slags
- 2003
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:10, s. 933-949
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Tidskriftsartikel (refereegranskat)abstract
- Various slags are produced as by-products in metallurgical processes or as residues in incineration processes. According to the origins and the characteristics, the main slags can be classified into three categories, namely ferrous slag, non-ferrous slag and incineration slag. This paper analysed and summarised the generation, characteristics and application of various slags, and discussed the potential effects of the slags on the environment. On this basis, a review of a number of methods for recovery of metals from the slags was made. It can be seen that a large amount of slags is produced each year. They usually contain a quantity of valuable metals except for blast furnace slag and they are actually a secondary resource of metals. By applying mineral processing technologies, such as crushing, grinding, magnetic separation, eddy current separation, flotation and so on, leaching or roasting, it is possible to recover metals such as Fe, Cr, Cu, Al, Pb, Zn, Co, Ni, Nb, Ta, Au, and Ag etc. from the slags. Recovery of metals from the slags and utilisation of the slags are important not only for saving metal resources, but also for protecting the environment.
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| 8. |
- Todorovic, Jelena, et al.
(författare)
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Solidification with water as a treatment method for air pollution control residues
- 2003
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 621-629
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Tidskriftsartikel (refereegranskat)abstract
- The process of solidification with water was studied on air pollution control (APC) residues from incineration of refuse-derived fuel (RDF) regarding mechanical strength and leaching behaviour of solidified material. Factorial design in two levels was applied to investigate the impact of water addition, time, and temperature to mechanical strength of solidified material. Factors time and temperature, as well as the interaction between the addition of water and time significantly (α=0.05) influenced the mechanical strength of solidified material. The diffusion-leaching test NEN 7345 was performed to investigate if the leaching behaviour of elements from solidified material was determined by diffusion. Since it was found that leaching is not diffusion controlled, the long-term leaching behaviour was not assessed. However, the investigation showed that some of the studied components (Al, Hg, Mn, Pb, Si, and Zn) could be considerably demobilised by solidification with water. Concentrations of As, Cd, Co, Cu, Fe, and Ni were either below or not quite above the detection limits to be included in the analysis of leaching behaviour. The elements least demobilised by solidification were Cl, Cr, K, and Na.
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| 9. |
- Yan, J. Y., et al.
(författare)
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The long-term acid neutralizing capacity of steel slag
- 2000
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 20:03-feb, s. 217-223
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Tidskriftsartikel (refereegranskat)abstract
- The long-term acid neutralizing capacity (ANC) of the electric are furnace slag investigated by batch pH titration, and the neutralizing processes of the slag were evaluated by reaction path modeling. Reaction time plays an important role for the determination of the ANC for the steel slag. The relatively slow reactions may give large contributions to the ANC for a long-term leaching process, pH-dependent reactivities of the steel slag were found in the high pH range. The neutralizing rates at high pH were much slower than that at relatively low pH. Below pH 9, the reaction rates became less pH-dependent and usually fast. The features of neutralizing reactions of the slag may be explained by its mineralogical composition and dissolution kinetics in the neutralizing processes.
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| 10. |
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| 11. |
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| 12. |
- Fallman, AM
(författare)
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Leaching of chromium and barium from steel slag in laboratory and field tests - a solubility controlled process?
- 2000
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 20:2-3, s. 149-154
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Tidskriftsartikel (refereegranskat)abstract
- Differences in concentrations in leachates and leaching conditions were found in laboratory and field tests on electric are furnace steel slag. Solid phases were assumed to control the leachate concentrations of chromium and barium. Geochemical modelling was used to indicate solubility controlling solid phases. The mineral BaSO4(c) and solid solutions of Ba(S,Cr)O-4 were predicted to control the concentrations of barium and chromium in the leachates, respectively. These solids were not expected to be present as primary minerals in the steel slag but were rapidly formed, within 6 h. (C) 2000 Elsevier Science Ltd. All rights reserved.
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| 13. |
- Hansen, TL, et al.
(författare)
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Method for determination of methane potentials of solid organic waste
- 2004
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Ingår i: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 24:4, s. 393-400
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Tidskriftsartikel (refereegranskat)abstract
- A laboratory procedure is described for measuring methane potentials of organic solid waste. Triplicate reactors with 10 grams of volatile solids were incubated at 55 degreesC with 400 ml of inoculum from a thermophilic biogas plant and the methane production was followed over a 50-day period by regular measurements of methane on a gas chromatograph. The procedure involves blanks as well as cellulose controls. Methane potentials have been measured for source-separated organic household waste and for individual waste materials. The procedure has been evaluated regarding practicality, workload, detection limit, repeatability and reproducibility as well as quality control procedures. For the source-separated organic household waste a methane potential of 495 ml CH4/g VS was found. For fat and oil a lag-phase of several days was seen. The protein sample was clearly inhibited and the maximal methane potential was therefore not achieved. For paper bags, starch and glucose 63, 84 and 94% of the theoretical methane potential was achieved respectively. A detection limit of 72.5 ml CH4/g VS was calculated from the results. This is acceptable, since the methane potential of the tested waste materials was in the range of 200-500 ml CH4/g VS. The determination of methane potentials is a biological method subject to relatively large variation due to the use of non-standardized inoculum and waste heterogeneity. Therefore, procedures for addressing repeatability and reproducibility are suggested.
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| 14. |
- la Cour Jansen, Jes, et al.
(författare)
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Assessment of sampling and chemical analysis of source--separated organic household waste
- 2004
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Ingår i: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 24:6, s. 541-549
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Tidskriftsartikel (refereegranskat)abstract
- The quality of the waste sampling procedure and chemical analysis was evaluated in a research program on characterization of organic waste obtained after disc screening of source-separated organic household waste. The sampling procedures focused on a truckload of waste and involved several steps of subsampling including shredding, mixing, blending, high-speed-blending, drying and milling prior to analysis of the organic waste with respect to ash content, crude fibers, crude fat, crude protein, sugar, starch, enzyme-digestible organic matter, P, N, C, H, S and calorific value. The statistical evaluation of the procedures involved 10 samples of the same truckload of waste obtained by splitting the sample at each level in the procedure according to a staggered, incomplete nested statistical design. Furthermore, one sample was analysed six times over a period of approximately one year. The statistical evaluation showed that no single step in the sampling procedure contributed with excessive variance and that the variance caused by the sampling procedure was approximately the same as the variance in the chemical analysis observed over a year. The variance varied with the analytical parameter but for most parameters the uncertainty was satisfactorily low (of the order of 3-10% expressed as the relative standard deviation, which is considered to be satisfactory for waste characterization). (C) 2004 Elsevier Ltd. All rights reserved.
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| 15. |
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| 16. |
- Nammari, Diauddin R., et al.
(författare)
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Emissions from a controlled fire in municipal solid waste bales
- 2004
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 24:1, s. 9-18
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Tidskriftsartikel (refereegranskat)abstract
- Environmental and safety aspects of seasonal storage of baled municipal solid waste to be used as fuel for energy production (waste fuel), was investigated and experiments were carried out on burning of bales. The flammability, combustion processes and emissions were studied by simulating, in small-scale, potential effects of a possible fire in full-scale bale storage area. Despite the high water content and the high density of the bales, after setting fire, the bales burned well, even though no risk for self-ignition exists. The following parameters of the combustion product were measured continuously: O2, CO2, CO, SO2, NO, NO2, NOx,THC, smoke gas rate and the temperature of the smoke. Soot particles in the smoke were collected and analysed for Hg, Pb, Cd, As,Ni, Cr, Mn, Cu, Co, Sb and V concentrations. The analysis of the moisture content, concentrations of Hg, Cd, HCl, HF, HBr, NH3, polyaromatic hydrocarbons (PAH), chlorinated and brominated dioxins (PCDD/F and PBrDD/F, respectively) were carried out. It was found that the PCDD/F levels (TEQs) varied according to the system used: 12.53 ng (I-TEF-88)/Nm3; 14.09 ng (I-TEF-99)/Nm3;13.86 ng (Eadons)/Nm3. The PAH concentration was 3.04 mg/Nm3. The contents of the metals in the smoke (with the exceptions of Pb and Cd with mean values of 1.74 and 0.36 mg/m3, respectively) were below the limit values established by the Swedish Ministry ofEnvironment for emissions from incineration plants [Swedish Ministry of Environment, (2002:1060), Förordning 2002:1060 omavfallsförbränning. Available from http://www.notisum.se/rnp/SLS/LAG/20021060.HTM]/EU-directive [(2000/76/EC), Directive 2000/76/EC, of the European Parliament and of the Council of 4 December 2000 on the Incineration of Waste. http://www.Scotland.gov.uk/library5/environment/iecda.pdf]. The HCl concentration was 10 times higher than the limit value (mean value of 99 mg/m3).
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| 17. |
- Roth, Liselott, et al.
(författare)
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Environmental evaluation of reuse of by-products as road construction materials in Sweden
- 2003
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Ingår i: Waste Management. - 0956-053X. ; 23:2, s. 107-116
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Tidskriftsartikel (refereegranskat)abstract
- Reuse of by-products in road construction is most often environmentally evaluated from the narrow perspective of the material itself, i.e. the material level. In this article, we argue that the current mainstream environmental evaluation of reuse of by-products in road construction should use wider system boundaries. In order to illustrate the importance of system boundaries to the final result, three additional levels that complement the material level, are applied to the environmental evaluation of reuse of by-products. In total these four levels of evaluation are, firstly, the material itself, mainly studied by leaching tests, secondly, the road environment studied by substance flow analysis, furthermore, a narrow life-cycle perspective and, finally, the industrial system level that addresses the reuse of by-products in a broader sense. Methods and tools applied to different levels emphasise different environmental aspects and consequently they are appropriate for addressing different questions. However, especially for the evaluation of environmental aspects on the industrial system level, there is a need to develop the methods. To apply these four levels to the evaluation would broaden the knowledge about the environmental impacts of the reuse of by-products. We argue that current leaching tests have to be complemented by the broader system boundaries used in substance flow studies and in life-cycle assessments in order to discuss the use of resources and environmental impacts from a wider perspective.
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