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- Herbert, Roger, 1966-, et al.
(författare)
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Using ash in a sustainable society, Swedish R&D programme 2002 - 2008
- 2009
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Ingår i: <em>Proceedings Sardinia 2009, Twelfth International Waste Management and Landfill Symposium</em>.
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Konferensbidrag (refereegranskat)abstract
- In Sweden, producers of combustion residues have since 2002 implemented acollaborative applied R&D programme aimed at the utilisation of combustion residues (ash). Thefuels are biomass, wastes, peat – any fuel but coal. In this contribution the main lines of theprogramme are described: ash a geotechnical material e.g. in roads, landfill construction andclosure and recycling nutrients in wood ash. Technical as well as environmental questions havebeen addressed, with a slight emphasis on environment as non-technical issues are important.Selected results from some of the ca 100 projects carried out since the inception of the AshProgramme are presented.
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- Kietlinska, Agnieszka, et al.
(författare)
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Nitrogen removal from landfill leachate using a compact constructed wetland and the effect of chemical pretreatment
- 2005
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Ingår i: Journal of Environmental Science and Health. Part A. - 1093-4529 .- 1532-4117. ; 40:07-jun, s. 1493-1506
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Tidskriftsartikel (refereegranskat)abstract
- Onsite treatment of leachate was implemented at the Tveta Landfill, adjacent to the city of Sodertalje, Sweden. The system consists of leachate collection in a pond, precipitation of metals with chemicals, a constructed wetland, and forest irrigation. This article describes the constructed wetland and its effectiveness at removing ammonia in the system. Pulsed-discharge hydrology and wetland ecology formed the basis for the development of a compact constructed wetland (CCW). The system presented here has most design similarities with vertical sub-surface flow wetlands, though this system is run in batch mode. Chemically purified leachate and untreated leachate were applied to separate sections of the CCW using a filling and emptying schedule. A leachate treatment cycle of about 14 days duration was used, involving a 7 day submerged phase followed by a 7 day drained period. The removal efficiency varied between 40 and 75% on a mass basis. A maximum mass removal rate of up to 5.1 g m(-1) d(-1) was achieved in wetlands receiving leachate after chemical pretreatment. In wetlands receiving non-treated leachate a net release of up to 18 g m(-2) N occurred in the form of nitrate. This indicated a considerable nitrification but limited denitrification in those systems. It was unclear whether the chemical treatment enhanced the nitrogen removal efficiency because of lower toxicity and/or content of fewer competing cations, or other mechanisms. Mechanisms responsible for the NH4-N removal in the CCW system have to be further investigated.
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- Tang, C A, et al.
(författare)
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Fracture spacing in layered materials and pattern transition from parallel to polygonal fractures
- 2006
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 73:5, s. 056120-28
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Tidskriftsartikel (refereegranskat)abstract
- We perform three-dimensional simulations of fracture growth in a three-layered plate model with an embedded heterogeneous layer under horizontal biaxial stretch (representing stretch from directional to isotropic) by the finite element approach. The fractures develop under a quasistatical, slowly increasing biaxial strain. The material inhomogeneities are accounted for by assigning each element a failure threshold that is defined by a given statistical distribution. A universal scale law of fracture spacing to biaxial strain in terms of principal stress ratio is well demonstrated in a three-dimensional fashion. The numerically obtained fracture patterns show a continuous pattern transition from parallel fractures, laddering fracture to polygonal fractures, which depends strongly on the far-field loading conditions in terms of principal stress ratio ......
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