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| 2. |
- Öberg, Tomas, 1956-, et al.
(författare)
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Different catalytic effects by copper and chromium on the formation and degradation of chlorinated aromatic compounds in fly ash.
- 2007
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Ingår i: Environmental Science and Technology. - Washington : American Chemical Society. - 0013-936X .- 1520-5851. ; 41:10, s. 3741-3746
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Tidskriftsartikel (refereegranskat)abstract
- Fly ash from municipal solid waste incineration may catalytically enhance the formation and degradation of chlorinated aromatic compounds. The activities of three Deacon catalysts in this process were investigated in a statistically designed experiment. Chlorides of copper, chromium, and nickel were added to fly ash samples and the resulting samples heated at 300 degrees C for 2 h in an air atmosphere. The addition of copper increases the formation of all chlorinated aromatic compounds except the low chlorinated congeners of polychlorinated dibenzo-p-dioxins and dibenzofurans. The addition of chromium decreased the formation of most chlorinated aromatic compounds except the highest chlorinated species, where it was without effect. The addition of nickel did not show any significant effect. The outcome of the experiment can be interpreted as two competing processes: the chlorination of aromatic rings and the oxidation of carbon-carbon and carbon-oxygen bonds. The delicate balance between chlorination and oxidation could probably be further exploited to minimize both the emissions and the net production of chlorinated aromatic compounds from combustion.
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| 3. |
- Öberg, Tomas, 1956-, et al.
(författare)
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Metal catalyzed formation of chlorinated aromatic compounds : a study of the correlation pattern in incinerator fly ash.
- 2007
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Ingår i: Chemosphere. - Oxford : Pergamon Press. - 0045-6535 .- 1879-1298. ; 67:9, s. S185-S190
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Tidskriftsartikel (refereegranskat)abstract
- Chlorinated aromatics are unintentionally formed and released from combustion and other thermal processes involving organic matter and chlorine. The catalytic activity of incinerator fly ash in the low-temperature formation of chlorinated aromatics has been demonstrated in both laboratory experiments and full-scale trials. Copper has been shown to be an effective catalyst, but several other transition metals possess a similar activity. Here results are reported from a series of full-scale combustion trials with different fractions of household and industrial wastes, with waste from forestry as a reference fuel. The composition of elements and chlorinated aromatics in the fly ash was evaluated with principal component analysis and partial least squares regression. The observed correlation pattern indicates that metals other than copper are of equal importance for the catalytic activity. Chromium and nickel are two of these metals, which may contribute to the de novo formation of chlorinated benzenes, phenols, PCDD and PCDF.
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| 4. |
- Öberg, Tomas, 1956-, et al.
(författare)
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The correlation pattern of fly ash components : Chromium as a potential catalyst in the thermal formation of chlorinated aromatic compounds
- 2004
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Ingår i: Environmental Chemistry. - 1448-2517 .- 1449-8979. ; 1:1, s. 18-21
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Tidskriftsartikel (refereegranskat)abstract
- Chlorinated aromatic compounds are unintentionally released from combustion sources into the environment. This thermal formation is catalyzed by fly ash components and much interest has been focussed on the role of copper. This study report results from a series of 16 full-scale trials with different fuel compositions. The correlation pattern of fly ash components seem to suggest that the catalytic effect may be due also to other metal oxychlorination catalysts. Chromium shows particularly strong and statistically significant correlations with many of the chlorinated phenols, benzenes, dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs).
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| 6. |
- Alriksson, Stina, et al.
(författare)
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Conjoint analysis for environmental evaluation : a review of methods and applications.
- 2008
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Ingår i: Environmental Science and Pollution Research. - : Springer Berlin. - 0944-1344 .- 1614-7499. ; 15:3, s. 244-257
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND, AIM AND SCOPE: Conjoint analysis and the related choice-modelling methods have been used for many years in marketing research to evaluate consumer behaviour and preferences for different kinds of product attributes. Recently, the number of applications in environmental science and management has started to grow. Conjoint analysis is found in many different forms, and the environmental studies evaluated in this review display the same range of methods as in other fields. The key characteristic of all these methods is that trade-offs are evaluated by jointly considering a number of important attributes. MAIN FEATURES: This paper is a review of the literature on environmental applications of conjoint analysis and assesses in which environmental area conjoint analysis has been most successful. The method and the design of the studies are reviewed as well. RESULTS: A total of 84 studies were found, dealing with environmental issues that were evaluated by conjoint analysis. The studies concern agriculture, ecosystem management, energy, environmental evaluation, forestry, land management, pollution, products, recreation, environmental risk analysis and waste management. DISCUSSION: Choice experiments seem to have a comparatively stronger position in environmental studies than elsewhere. Most of the environmental applications are related to natural resource management. This is somewhat surprising, but a number of reports have appeared also on product evaluation, which could be a key application area in the future. CONCLUSIONS: Compared to marketing and transportation, the number of environmental conjoint studies is rather small but increasing, and the method has proven to work effectively in eliciting preferences on environmental issues. In environmental issues, experimenters often use choice experiments, especially concerning ecosystem management and environmental evaluations. When it comes to evaluating preferences concerning agriculture, forestry, energy and products, a more traditional approach of conjoint analysis is favoured. RECOMMENDATIONS AND PERSPECTIVES: Two new areas of application are identified in this review--environmental communication and expert elicitation. Conjoint analysis can thus be developed into a useful instrument for environmental risk analysis and communication, both of which are necessary for an efficient approach to risk governance.
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| 7. |
- Alriksson, Stina, 1971-, et al.
(författare)
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Towards a closed steel eco-cycle - cojoint analysis as a decision tool
- 2005
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Ingår i: Proceedings Kalmar ECO-TECH´ 05. - Kalmar : Högskolan i Kalmar. ; , s. 27-36
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Konferensbidrag (refereegranskat)abstract
- The Swedish steel industry has over the past 20 years made substantial efforts to promote energy efficiency and environment protection. However, the dominant part of these investments has been directed to the individual production sites, most of which today have 'solved' their own acute environmental problems. The focus has therefore switched to the properties and performance of the steel products where the evaluation of environmental performance is a complex task that often requires simultaneous consideration of many different attributes. Conjoint analysis is commonly used in marketing research, to evaluate how consumers appreciate specific attributes in products. It has also been widely used in health care, traffic planning and quality management. Conjoint analysis has also been applied to environmental issues such as energy, recreation, environmental valuation, ecosystem management, consumer preferences to products, public preferences to industrial projects, waste management, and environmental policy development. This previous research has shown that the method is well suited for evaluating environmental issues. Here we briefly present the methodology and review some papers on environmental applications. It is our intention to use this approach as a tool to integrate environmental considerations into both process and product development within the steel industry.
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| 8. |
- Bergius, Kristine, et al.
(författare)
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Initial screening of contaminated land : a comparison of US and Swedish methods.
- 2007
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Ingår i: Environmental Management. - : Springer Science and Business Media LLC. - 0364-152X .- 1432-1009. ; 39:2, s. 226-34
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Tidskriftsartikel (refereegranskat)abstract
- Preliminary surveys are used to prioritize between contaminated sites to select those to be investigated more thoroughly. The data-gathering steps are almost identical between countries; however, the assessment procedures differ significantly. In this study, we have investigated 21 contaminated sites assessed as belonging to the high-risk or the very high-risk class using the Swedish Methods for Inventories of Contaminated Sites (MICS). We then applied the US Preliminary Assessment (PA) method to the same sites and compared the results and conclusions from the two screening procedures. In both cases, all sites were recommended for further investigation and the two approaches seem to corroborate one another; however, the PA assessment scores and the preliminary MICS classifications did not correlate. The results obtained with the PA method were easier to explain than the final MICS classification. The PA method also seems more transparent and easier to standardize, although objections could be made regarding the weighting scheme, because the outcome in this study was entirely dependent on the surface exposure pathway. However, to examine this in greater detail, it is necessary to include sites with less contamination: The importance of preliminary surveys in the overall risk management process gives a strong motivation for such an evaluation. Generally, the lack of research and scientific support for the various assessment procedures in use suggests that there is a need for method development, standardization, and validation.
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| 9. |
- Cederqvist, Lars, et al.
(författare)
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Improved process stability during friction stir welding of 5 cm thick copper canisters through shoulder geometry and parameter studies
- 2009
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Ingår i: Science and technology of welding and joining. - London : Institute of Materials. - 1362-1718 .- 1743-2936. ; 14:2, s. 178-184
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Tidskriftsartikel (refereegranskat)abstract
- The spent nuclear fuel from Swedish power plants will be placed in copper canisters that are sealed with friction stir welding and the stability and robustness of this process is now being optimised in three steps: first, the shoulder geometry was identified that produced the most stable weld cycle, then the welding parameters were optimised for that geometry with regards to stability, and finally, the chosen geometry and welding parameters were verified and evaluated during multiple weld cycles. The shoulder study showed that stable welds could be produced repeatedly with a convex scroll geometry which proved more stable than various concave and flat scroll geometries. In the subsequent parameter study, not only were the most stable values for the welding parameters derived, but a clear relationship was shown between power input and tool temperature. This relationship can be used to more accurately control the process within the parameter windows, not only for this application but for other applications where the welding temperature needs to be kept within a specified range. Similarly, the potential of the convex scroll shoulder geometry for use in applications with other metals and thicknesses is evident.
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| 10. |
- Cederqvist, Lars, et al.
(författare)
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Reliability study of friction stir welded copper canisters containing Sweden's nuclear waste
- 2008
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Ingår i: Reliability Engineering & System Safety. - : Elsevier. - 0951-8320 .- 1879-0836. ; 93:10, s. 1491-1499
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Tidskriftsartikel (refereegranskat)abstract
- The plan for the final disposal of spent fuel from Swedish nuclear power plants is to place it in copper canisters that are sealed and stored in a deep repository. The canisters will be sealed by friction stir welding (FSW) and the reliability of this process has now been evaluated. The reliability study was performed in three steps: first an optimization experiment to identify optimal process settings and establish the process window; then a demonstration experiment with welding under production-like conditions; and finally a post-demonstration series to evaluate an adjustment in the welding equipment. A process window was defined around the optimal process setting, i.e., the limits within which the welding variables must lie in order for the process to produce the desired result. In the demonstration experiment, a series of 20 sealing welds was carried out under production-like conditions. The maximum discontinuity in each weld — detected by non-destructive testing — was fitted to a generalized extreme value distribution. The 95% confidence interval for the maximum discontinuity in a production series of 4500 canisters was estimated at 4.5–7.7 mm. The best estimate from the post-demonstration series suggests that the maximum size of a discontinuity will not exceed 2.3 mm. A main conclusion is that the FSW process produces reliable results, fulfilling the predetermined requirements for minimum copper thickness by a very good margin.
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