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- Andreas, Lale, et al.
(författare)
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Hydraulic performance of a land-fill top cover based on steel slag
- 2014
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Ingår i: Sardinia 2013. - Cagliari : CISA, Environmental Sanitary Engineering Centre.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The steel industry is expanding and following the amount of produced steel, more and more by-products and residuals are generated. About 17.6 million tonnes of steel slags arise in Europe every year. In Sweden about 18 % of the iron- and steelmaking slags are landfilled (Jernkontoret, 2012). One application for steel slags are landfill covers where large amounts of virgin materials are needed. The legal requirement in Sweden is directed towards the maxi¬mum amount of lea¬chate generated at the bottom of the landfill: < 5 and < 50 l (m2*a)-1 for landfill class 1 and 2, respec¬ti¬vely. To secure these demands, a layer of low permeability is needed to reduce water infiltration. The hydraulic load of this layer ought to be controlled by a protective water balance layer and an effective drainage layer.Previous investigations indicate that steel slags can be used as construction material for both liner and drainage layer (Herrmann et al., 2010). In order to verify this in full scale, five tests areas (A1-5) were constructed at a municipal landfill in Sweden between 2005 and 2011. The areas were designed using different mixtures of steel slags from the local steel company in the liner. The purpose of this study was to evaluate the hydraulic performance of the cover during the first years after installation.The design of the cover construction was varied like this: a mixture of 50 % electric arc furnace slag (EAFS) and 50 % ladle slag (LS) was tested as liner material in the first test area (A1). A2 and A3 were built using less LS and coarser fractions of EAFS since laboratory tests had given satisfactory results also for these recipes. High infiltration rates in A2 and 3 led to a return to the original weight proportions in A4 and 5, yet another EAF slag was introduced in these areas. The mixing and construction techniques were refined during the first years of the project time: while A1 was built with rather poorly conceived technique, as of A3 the method can be considered as technically mature and approved.The liner performance was evaluated by lysimetry: 10 lysimeters were installed below each test area. The infiltration below the liner corresponded to 44, 74, 71, 19 and 0.4 l/m2*year for A1 to A5. Compared to the legal limit of 50 l/m2*year, the covers of A2 and A3 allowed about 50 % more water to enter the landfill than stipulated.An initial increase of the infiltration was observed, which most likely is related to increasing water saturation of the liner material in the first period after construction. The saturation occurred fastest in A2, where basically no initial increase was observed, probably due to the long time that elapsed between construction and the first sampling event (260 days). In contrast, the saturation in A1 and A4 was quite slow which can be related to the smaller particle size of the slags in these areas and, hence, a less porous liner material. The decrease in A2 and A3 might be explained by mineral transformations within the slag matrix such as carbonation of calcium and magnesium leading to the precipitation of carbonates in the pores of the liner material. Future observations will show if the decreasing trend in A2 and A3 remains such that the infiltration eventually reaches a level falling below the legal limit.The results show that the infiltration criteria can be fulfilled under the condition that at least 50 % of the liner mix consists of ladle slag, a fine-grained slag with cementitious properties. With few adaptations the steel slag can be used with standard construction processes.
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- Bauer, Torben, et al.
(författare)
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Finding new sewage sludge treatment solutions for the arctic city of Kiruna
- 2020
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Ingår i: VENICE2020 – 8th International Symposium on Energy from Biomass and Waste. - : CISA Publisher.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- As Sweden’s northernmost city, Kiruna has very particular demands for its sewage sludge treatment. This study tests hydrothermal carbonisation (HTC) as a treatment option for Kiruna to stabilize the sewage sludge, facilitate its transport by volume reduction and prepare the sludge for recovery of resources. The study consists out of an experimental part and a lifecycle assessment (LCA) development, which also gives options to use the results in other LCA scenarios incorporating HTC. Preliminary results show that HTC is a treatment that can fulfil Kiruna’s demands and that an optimization of the treatment’s settings can greatly increase the efficiency and effectiveness of the HTC treatment.
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| 5. |
- Bauer, Torben
(författare)
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Sustainable Sewage Sludge Management : Addressing Multidisciplinary Challenges
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This PhD thesis focuses on multidisciplinary challenges in sewage sludge management and how they can be addressed to increase sustainability. Sewage sludge is the residual from wastewater treatment. It contains both resources and contaminants making its management challenging. In the past sewage sludge was often used as a fertilizer in agriculture, a practice that is still used in several countries. Today, this practice gets questioned in Europe and especially in Sweden due to the presence of contaminants in the sludge. At the same time, the resources in the sludge get into a stronger focus as society moves towards a circular economy and food production should get more resilient in a world with geopolitical challenges. In sustainable sewage sludge management, the two goals of immobilising/destroying the contaminants and utilizing the resources in the sludge are combined. This thesis identifies challenges in various disciplines and provides potential solutions to make sewage sludge management more sustainable. The discussed challenges cover the following areas: legislation (EU and Sweden), perception of sewage sludge (Sweden), research on sewage sludge management (international), and combinations of treatment methods. Results show that outdated legislation in Sweden creates insecurities, while the negative perception of sewage sludge in Swedish society further aggravates these insecurities. Although technical solutions are available or under development, e.g., treatment combinations that can separate resources and contaminants, actors in Sweden remain hesitant due to the aforementioned insecurities. This thesis emphasizes that interdisciplinary approaches, and dialogues between different actor groups and society are essential. The multitude of challenges requires solutions that combine technical and non-technical approaches. Therefore, this thesis provides recommendations for more sustainable sewage sludge management practices, including updating legislation.
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- Bogner, Jean E., et al.
(författare)
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Early diagenesis of garbage : landfills as engineered anoxic basins
- 1996
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Ingår i: Geological Society of America, 28th annual meeting, Denver, CO, United States, Oct. 28-31, 1996. - : Geological Society of America. ; , s. 257-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Early diagenesis of buried organic carbon in anoxic basins is dominated by microbial decomposition processes at temperatures and pressure slightly above ambient. Such conditions also describe decomposition of refuse in sanitary landfills and provide a reasonable model for systematic studies of their long-term geochemistry. For shorter time frame (decades), controlled high-solids anaerobic digestion systems provide a second model for investigation of optimized landfill systems. In this paper, we introduce both models through a series of preliminary mass-balances to develop a realistic overview of landfill processes, especially emphasizing carbon cycling in field settings over various time-frames. The terminal product of short-term anaerobic decomposition is methane--produced by methanogenic bacteria from some fraction of organic carbon landfilled. Laboratory studies of optimized landfill systems (ours and from the literature) indicate that, at best, 25-45% of organic carbon is converted to biogas carbon (methane and carbon dioxide); such percentages are rarely attained in field settings. Most of the methane is produced from cellulosic substrates while lignin substrates are recalcitrant, with lignin carbon entering sedimentary storage for time frames longer than the four decades of widespread landfilling experience in the U.S. and western Europe. Over time frames in excess of centuries, further transformations via kerogen pathways are possible but highly speculative. Certainly, exhumation of old refuse at archeologic sites indicates that organic carbon preservation can be documented for at least one or two millenia. From controlled incubation of unamended field samples and from field studies of net methane emissions, it is clear that rates of methane production and consumption both vary of several orders of magnitude in field settings; their dynamic are rapid and complex spatially and temporally. Unraveling these dynamics is necessary to suggest the overall relevance of these engineered anoxic basins to issues of atmospheric methane increases and terrestrial carbon storage.
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| 9. |
- Dahlén, Lisa, et al.
(författare)
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Trends in municipal solid waste composition
- 2004
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Ingår i: The 3rd Intercontinental Landfill Research Symposium November 29th - December 2nd, 2004 in Toya, Hokkaido Japan. - Hokkaido : Center for Applied Ethics and Philosophy, Hokkaido University. ; , s. 157-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 10. |
- De Windt, L., et al.
(författare)
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Reactive transport modeling of leachate evolution of MSWI bottom ash used as road basement : Hérouville (France) and Dåva (Sweden) sites
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The recycling of municipal solid waste of incineration (MSWI) bottom ash as aggregates for road basement requires a better characterization of the evolution of leachate chemistry over a timescale of many decades. In this paper, a common reactive transport model is applied to the Hérouville (France) and Dåva (Sweden) pilot roads whose leachate emissions have been sampled during 10 and 6 years, respectively. The model considers simultaneously the hydrodynamic processes (rain water infiltration, advective and diffusive transport), pH-buffering and solubility-controlled processes by secondary minerals, ageing by atmospheric carbonation, and the leachate chemistry (major elements and trace metals such as Al, Cu, Pb). The evolution of pH is fairly well simulated with the following pH-buffering sequence: portlandite, calcium silicate hydrate (CSH), ettringite and, finally, calcite. The quantity of CO2 dissolved in the percolating rain water is generally not sufficient to explain the pH evolution and carbonation processes, requiring atmospheric gaseous inputs. The relation between pH evolution and element release is discussed for both sites. Calculated Pb release is overestimated when based on solubility-controlled mechanisms only. Edge effects are shown to be important at both sites with an emphasis of carbonation and release of non reactive elements. Temperature has no significant effect on the calculated leachate chemistry in the range of 5 - 30° C, except at high pH.
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