| 1. |
- Allard, Bert, 1945-, et al.
(author)
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Metal Exchangeability in the REE-Enriched Biogenic Mn Oxide Birnessite from Ytterby, Sweden
- 2023
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In: Minerals. - : MDPI. - 2075-163X. ; 13:8
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Journal article (peer-reviewed)abstract
- A black substance exuding from fractures was observed in 2012 in Ytterby mine, Sweden, and identified in 2017 as birnessite with the composition Mx[Mn(III,IV)](2)O-4 center dot(H2O)n. M is usually calcium and sodium, with x around 0.5. The Ytterby birnessite is unique, with M being calcium, magnesium, and also rare earth elements (REEs) constituting up to 2% of the total metal content. The biogenic origin of the birnessite was established in 2018. Analysis of the microbial processes leading to the birnessite formation and the REE enrichment has continued since then. The process is fast and dynamic, as indicated by the depletion of manganese and of REE and other metals in the fracture water during the passage over the precipitation zone in the mine tunnel. Studies of the exchangeability of metals in the structure are the main objective of the present program. Exposure to solutions of sodium, calcium, lanthanum, and iron led to exchanges and altered distribution of the metals in the birnessite, however, generating phases with almost identical structures after the exchanges, and no new mineral phases were detected. Exchangeability was more efficient for trivalent elements (REE) over divalent (calcium) and monovalent (sodium) elements of a similar size (ionic radii 90-100 pm).
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| 2. |
- Liem-Nguyen, Van, et al.
(author)
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Removal mechanism of arsenic (V) by stainless steel slags obtained from scrap metal recycling
- 2020
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In: Journal of Environmental Chemical Engineering. - : Elsevier. - 2213-3437. ; 8:4
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Journal article (peer-reviewed)abstract
- With this study, the removal mechanisms of arsenate by steel slag and its potential for treatment of contaminated water were elucidated. While original slag showed a poor fit to the Langmuir equation (R2 = 0.960), washed slag (the original slag is washed by low pH water solutions to remove readily soluble oxides) conformed better (R2 = 0.995). An initial pH of 2.0 give optimal adsorption, with a strong impact from the chemical speciation observed with highest efficiency for the fully protonated (OH)3AsO form. Adsorption capacity of the slag is 4.0 mg g−1, while together with precipitation the retention capacity reaches 13.7 mg g−1. However, removal by precipitation is a non-steady process due to re-dissolution of Ca3(AsO4)2(s). The washed slag shows a similar adsorption capacity to the original one but has not as strong alkaline properties. Batch experiment shows fast adsorption kinetics and column loading tests indicate an instant adsorption kinetics with 80 % As(V) removal for a 10 mg L−1 As(V) solution by 1.0 g of washed slag using a solution flowrate of 1 mL min−1. Common ions like sulfate, carbonate, chloride, iron(III), humic acid and fulvic acid do not significantly interfere with the removal efficiency. In combination with limited hazardous metals leaching, the slag is thus appropriate for use as a filter material for treatment of contaminated water and it has been successfully applied as filter material for treatment of arsenate spiked natural water sample with average removal efficiency of 84 % (solid to liquid ratio of 200).
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| 3. |
- Nilsson, Charlotte, 1985-
(author)
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Phosphorus recovery from sewage sludge : Implications of incineration and enrichment potential of produced ashes
- 2024
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Doctoral thesis (other academic/artistic)abstract
- Sewage sludge is a promising source for phosphorus recovery, but it also contains contaminants (organics, metals) which must be removed. The most commonly used practice is incineration, where organic contaminants are decomposed. This treatment entirely alters the chemical profile of the material, and information regarding this transformation is crucial for development of durable handling and recovery processes. The aims of this project were to; 1)study the chemical speciation of phosphorus and metals in sewage sludge and their ashes after incineration; 2)evaluate the impact of iron and aluminium on the phosphorus redistribution following incineration, and 3)investigate the potential for sewage sludge ashes to function as sorbents for phosphorus and metals. Sludge and ashes from 10 municipal wastewater treatment plants in Sweden were sampled and characterized for their elemental composition, mineral components, leachability and chemical speciation. Major elements were Fe and Al (added in the wastewater treatment process), Ca, Mg, Na and K. Phosphorus was predominantly associated with aluminium and iron in the sludge, but after incineration there was a shift to calcium associated species, which is preferred for phosphorus recovery. This alteration was hampered by high concentrations of aluminium, why its concentration should be kept at a minimum. The incineration caused changes in speciation, where more ordered mineral phases where created, hematite being the major component. The ashes were successfully used as sorbents for both metals and phosphorus. Adsorption isotherms and inter particle-diffusion modelling indicated that the sorption takes place in two stages, where the first is a rapid process on the surfaces, while the second is slower and includes interactions with the pores of the material.
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| 4. |
- Nilsson, Charlotte, 1985-, et al.
(author)
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Phosphorus speciation in sewage sludge and their ashes after incineration as a function of treatment processes
- 2024
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In: Waste Management & Research. - : Sage Publications. - 0734-242X .- 1096-3669.
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Journal article (peer-reviewed)abstract
- Phosphorus (P) is a key component in agricultural fertilizers, but it is also a scarce resource, why its recycling has been thoroughly investigated and one promising resources is sewage sludge. Because of stricter regulations in terms of sludge disposal, thermal treatment (e.g. incineration) has become an attractive option. The incineration process alters the chemical speciation of P in favour to calcium-associated (apatite, apatite phosphorus (AP)) species, which is preferred for P recovery. In order to achieve qualitatively transformation, it is important to identify limiting or promoting factors. This study reports on the impact of iron, aluminium and calcium on the transformation of iron- and aluminium-phosphate (NAIP) to AP species, assessed by studying sludge and ash from 10 municipal wastewater treatment plants in Sweden. The effect of iron and aluminium added in the treatment processes was also evaluated. The obtained results show that high calcium concentration favours formation of AP species in both sludge and ashes, whereas high concentration of iron and aluminium favours formation of NAIP species in the sludge. The transformation from NAIP to AP species is hampered by aluminium, irrespectively of its origin, whereas no such correlations could be seen for iron. Therefore, in order to enable efficient P recovery from sewage sludge ash, the amount of aluminium added in the treatment process, as well as its concentration in influent streams to the treatment plants, must be limited.
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| 5. |
- Nilsson, Charlotte, 1985-, et al.
(author)
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Phosphorus speciation in sewage sludge from three municipal wastewater treatment plants in Sweden and their ashes after incineration
- 2022
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In: Waste Management & Research. - : Sage Publications. - 0734-242X .- 1096-3669. ; 40:8, s. 1267-1276
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Journal article (peer-reviewed)abstract
- Given the high efficiency in phosphorus removal at municipal wastewater treatment plants (MMWWTP), sewage sludge constitutes a promising resource for phosphorus (P) recovery. Sewage sludge is, however, a complex matrix and its direct use as fertiliser is limited by its content of metals/metalloids and organic pollutants. In order to increase its usability as a potential resource of P, there is a need for increased knowledge on phosphorus speciation in these matrices. The sludge composition is highly influenced by local conditions (i.e. wastewater composition and treatment method), and it is therefore important to study sludge from several MMWWTPs. In this study, three different protocols for sequential extraction were utilised to investigate the chemical speciation of phosphorus in sludge from three different MMWWTP sludges in Sweden, as well as in corresponding ashes following incineration. The results showed that the total amounts of phosphorus ranged from 26 to 32 mg g-1 sludge (dry weight), of which 79-94% was inorganically bound (IP). In the sludge, 21-30% of the IP was associated with calcium (Ca-P), which is the preferred species for fertiliser production. Following incineration, this fraction increased to 54-56%, mainly due to transformation of iron-associated phosphorus (Fe-P), while aluminium-associated species of phosphorus (Al-P) remained unaltered. The results from this study confirm that incineration is a suitable treatment for sewage sludge in terms of potential phosphorus recovery.
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| 6. |
- Peters, Anne-Kathrin, et al.
(author)
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Care ethics to develop computing and engineering education for sustainability
- 2020
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In: 2020 IEEE Frontiers in Education Conference (FIE). - : IEEE. - 9781728189611 - 9781728189628
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Conference paper (peer-reviewed)abstract
- The aim of this special session is to connect researchers interested in computing and engineering education for sustainability. We will explore the use of care and care ethics as a theoretical perspective to develop sustainability education. Theoretical discussions in environmental and sustainability education (ESE) research and feminist research will be introduced to develop an understanding of care for education. Those theories will be illustrated and motivated based on concrete examples in computing and computing education. The participants get to choose among four different topics of discussion in the session, 1) the role of education to prepare for care, 2) theoretical discussions of care as a concept to develop education and education research, 3) pedagogical methods to foster care, 4) care and responsibility in the curriculum. The outcome of this session is two-fold: The participants will gain new ways of conceiving education for human and planetary well-being and they will get to know researchers and educational developers with an interest in and experiences with sustainability education.
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| 7. |
- Åhlgren, Kristina, 1976-
(author)
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Environmental impact of alum shale mining in Kvarntorp, Närke, Sweden
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Due to scarcity of imported liquid fuel during World War II, alum shale was mined for oil production in the Kvarntorp area 1942-1966. The shale contains both organic matter (kerogen) and elevated concentrations of trace elements such as molybdenum, nickel, uranium and vanadium. Today there are several pit lakes in the area and a 100-meter-high waste deposit, Kvarntorpshögen, consisting mostly of crushed and burned shale but also some unburned crushed shale and lime waste.The aim of this study was to get a better understanding of the environmental impact of alum shale mining with focus on trace metal release. During the production era, the surroundings were highly affected by both sulphur rich flue gas emissions and bad water quality in downstream waters. The former mining activities show impact also today, with higher concentrations in downstream water than upstream the area. Analyses and leaching tests of solid samples have shown pyrite weathering in shale and unburned shale waste with release of for example nickel and uranium.Analyses of groundwater in eleven wells around the deposit show ongoing leaching of both shale waste generating a circumneutral leachate and unprocessed shale leading to acidic leachates.All pit lakes in contact with alum shale waste or the shale horizon show elevated sulphate concentrations indicating pyrite weathering, although only one is still acidic today. Also Norrtorpssjön was acidic until a pH rise due to adjacent dumping of alkaline waste. The pH increase was followed by a decrease in aluminium, cobalt, magnesium and nickel.Surface water analysis show that the waste deposit is estimated to contribute with less than a fifth of the mass transport whereas the western pit lakes contribute with the largest part.
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