| 1. |
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| 2. |
- Brännvall, Evelina, et al.
(författare)
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Ageing of ashes in a landfill top cover
- 2011
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Ingår i: SARDINIA 2011. - Cagliari : CISA Publisher, Italy.
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Konferensbidrag (refereegranskat)abstract
- This paper is based on studies on the effects of accelerated ageing on refuse-derived-fuel (RDF) fly ashes, in experiments under controlled laboratory conditions, intended to derive models to predict the stability of RDF fly ashes used in a landfill liner and the mineralogi-cal changes that occur in them. A reduced factorial design was applied, followed by multivariate data analysis, to evaluate the effects of five factors — carbon dioxide (CO2) levels, temperature, relative air humidity (RH), time and the quality of added water — on mineral transformations within the ashes, and leaching behaviour. The pH values of these ash specimens ranged from 7.2 to 7.6, indicating advanced carbonation. Ageing decreased pH values from 12.4 to 7.2, conse-quently affecting the leaching behaviour of most chemicals measured in the leachates. Levels of Ba, Ca, Cl, Cr, Cu, Pb, K and Na decreased over the study period while those of Mg, Zn and SO4 increased. Clay minerals could not be detected neither in fresh nor in aged ashes. However, geo-chemical modelling indicated that such minerals may precipitate.
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| 3. |
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| 4. |
- Malovanyy, Andriy, et al.
(författare)
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Rening av PFAS-förorenat lakvatten med jonbytesprocessen: pilotförsök med regenerering
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med projektet var att studera rening av PFAS-förorenat lakvatten med jonbytare med fokus på avskiljning av substanser med kort och medellång kolkedja. Dessa substanser avskiljs dåligt med de flesta tekniker. Tidigare studier har visat att jonbytarfilter avskiljer substanserna initialt när filtret tas i drift men reduktionsgraden minskar snabbt. För att behålla bra avskiljning av dessa substanser behöver jonbytarmassan därför bytas ofta, vilket medför en hög reningskostnad. Några studier har visat att jonbytarmassa kan regenereras från PFAS och användas flera upprepade gånger, vilket har potential att minska reningskostnaden och behålla bra reduktion av de kortare PFAS.Regenerering av jonbytare har dock inte testats tidigare vid rening av lakvatten, bara vid rening av andra vattenströmmar. Dessutom behövde hantering av den förbrukade regenereringslösningen som innehåller höga PFAS halter studeras.I föreliggande studie gjordes litteraturgenomgång, försök i labb-, bänk-, och pilotskala samt processberäkningar och kostnadskalkyler för att studera hur regenerering av jonbytare och återvinning av regenereringslösningen kan tillämpas vid rening av PFAS-förorenat vatten. Försöken utfördes vid Ragn-Sells avfallsanläggning Högbytorp.Kortvariga labbförsök visade att det finns flera typer av jonbytare från de flesta stora leverantörer som fungerar bra vid rening av lakvatten från PFAS. De mest lovande av dessa testades avseende regenerering med två olika regenereringslösningar. En indikation från labbförsöken var att det är möjligt att regenerera jonbytarna och behålla liknande kapacitet i fler cykler av sorption-regenerering.Pilotförsöken genomfördes i en anläggning bestående av förbehandling av lakvatten genom fällning, sedimentering, och ultrafiltrering följt av två jonbytarfilter som kördes i serie eller parallellt. Förbehandlingen fungerade för det mesta bra och producerade ett partikelfritt vatten, dock med en hög dos av en fällningskemikalie. Jonbytarfiltren renade det förbehandlade vattnet tills genombrott av medellånga PFAS observerades. Sedan regenererades ett av jonbytarfiltren och filtret togs i drift igen för att undersöka hur regenereringen påverkade kapaciteten för PFAS-reduktion.Resultaten visade att det mesta av sorberade PFAS tvättades bort från massan och att den regenererade massan hade en kapacitet som liknande en ny.Den regenereringslösning som visade sig fungera bra i labb-, bänk-, och pilotskaleförsöken var 1% NH4Cl i 80%vol etanol. För regenerering av 1 m3 jonbytarmassa krävdes minst 13 m3 av lösningen. Att regenerera jonbytare och skicka lösningen på destruktion kostar mer än att köpa ny jonbytarmassa. För att regenereringen ska vara ekonomiskt motiverad behöver den förbrukade regenereringslösningen återanvändas och/eller kemikalier från den behöver återvinnas. I projektet studerades två alternativ för återvinning av lösningen – destillering och nanofiltrering. Båda metoderna fungerade bra och separerade >98% av PFAS från regenereringslösningen. Koncentratet, som innehåller PFAS i halter 1 000 – 1 700 gånger högre än i inkommande lakvatten, kan då skickas på destruktion medan den renade regenereringslösningen återanvändas.En grov kostnadsanalys visade att för de flöden och halter som förekommer i lakvatten på Högbytorp skulle regenerering och återvinning av regenereringslösningen med nanofiltrering vara ekonomiskt motiverad om en bra reduktion av medellånga PFAS eller väldigt höga reduktionsgrader (>95%) av de längre PFAS skulle krävas. Däremot, om 90% reduktionsgrad eller lägre bedöms vara tillräckligt för ΣPFAS4 eller ΣPFOAekv så bedöms regenerering och återvinning av regenereringslösningen i en egen anläggning att inte vara ekonomiskt motiverat. Däremot finns en stor potential för en gemensam anläggning för regenerering av jonbytare från flera avfallsanläggningar eller andra verksamheter, liknande som det görs idag med reaktivering av aktivt kol.
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| 5. |
- Travar, Igor, et al.
(författare)
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Assessing the environmental impact of ashes used in a landfill cover construction
- 2009
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 29:4, s. 1336-1346
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Tidskriftsartikel (refereegranskat)abstract
- Large amounts of construction materials will be needed in Europe in anticipation for capping landfills that will be closed due to the tightening up of landfill legislation. This study was conducted to assess the potential environmental impacts of using refuse derived fuel (RDF) and municipal solid waste incineration (MSWI) ashes as substitutes for natural materials in landfill cover designs. The leaching of substances from a full-scale landfill cover test area built with different fly and bottom ashes was evaluated based on laboratory tests and field monitoring. The water that drained off above the liner (drainage) and the water that percolated through the liner into the landfill (leachate) were contaminated with Cl-, nitrogen and several trace elements (e.g., As, Cu, Mo, Ni and Se). The drainage from layers containing ash will probably require pre-treatment before discharge. The leachate quality from the ash cover is expected to have a minor influence on overall landfill leachate quality because the amounts generated from the ash covers were low, <3-30 l (m2 yr)-1. Geochemical modelling indicated that precipitation of clay minerals and other secondary compounds in the ash liner was possible within 3 years after construction, which could contribute to the retention of trace elements in the liner in the long term. Hence, from an environmental view point, the placement of ashes in layers above the liner is more critical than within the liner.
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| 6. |
- Travar, Igor, et al.
(författare)
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Challenges in the PFAS Remediation of Soil and Landfill Leachate: A Review
- 2021
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Ingår i: Advances in Environmental and Engineering Research. - : Lidsen publishing. - 2766-6190. ; 2:2
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Forskningsöversikt (refereegranskat)abstract
- The use of per-and poly-fluoroalkyl substances (PFAS) has resulted in the contamination of different environmental matrices. In EU countries, the sites contaminated with PFAS are usually remediated by excavating the soil and disposing of it in a landfill, as no in-situ or on-site techniques capable of treating large quantities of soil cost-effectively have been developed. Landfilling of PFAS-contaminated soil is one of the sources of PFAS in landfill leachate. In this paper, the physical and chemical treatment methods to remove PFAS from soils and landfill leachates are described. Among the challenges that may limit the remediation of contaminated sites, we highlight the lack of strict regulation of PFAS in soils, the cost, the ineffectiveness of some methods for the remediation of certain PFAS compounds, and the limitation of the environmental matrices.
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| 7. |
- Travar, Igor, et al.
(författare)
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Development of drainage water quality from a landfill cover built with secondary construction materials
- 2015
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 35, s. 148-158
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the drainage water quality from a landfill cover built with secondary construction materials (SCM), fly ash (FA), bottom ash (BA) sewage sludge, compost and its changes over time. Column tests, physical simulation models and a full scale field test were conducted. While the laboratory tests showed a clear trend for all studied constituents towards reduced concentrations over time, the concentrations in the field fluctuated considerably. The primary contaminants in the drainage water were Cl−, N, dissolved organic matter and Cd, Cu, Ni, Zn with initial concentrations one to three orders of magnitude above the discharge values to the local recipient. Using a sludge/FA mixture in the protection layer resulted in less contaminated drainage water compared to a sludge/BA mixture. If the leaching conditions in the landfill cover change from reduced to oxidized, the release of trace elements from ashes is expected to last about one decade longer while the release of N and organic matter from the sludge can be shortened with about two–three decades. The observed concentration levels and their expected development over time require drainage water treatment for at least three to four decades before the water can be discharged directly to the recipient.
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| 8. |
- Travar, Igor, et al.
(författare)
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Development of drainage water quality from landfill covers built with ashes and sewage sludge
- 2009
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Ingår i: SARDINIA 2009. - Cagliari : CISA, Environmental Sanitary Engineering Centre. - 9788862650076
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Konferensbidrag (refereegranskat)abstract
- An alternative to virgin and artificial materials in landfill cover can be various types of waste materials like ashes and sewage sludge. From the environmental point of view, the most interesting question to study is the quality of the drainage water generated above the liner in landfill cover built with waste materials. Thus, the main aim of this paper is the evaluation of drainage water quality and time required for its treatment. Results from a full scale test, physical models and a column test were used in the evaluation of the drainage water quality development. The main contaminants identified in drainage water were N-tot, As, Cu, Cd, Pb, Zn and Ni. The laboratory tests showed higher concentrations of N-tot, NH4-N, TOC, As and Pb, but lower values of Cl, Zn, Ba and Ni in comparison with drainage water from the field. It was probably a result of different factors that may have influence on leaching but interactions of the protection layer with the vegetation layer and the liner surface are expected to influence the results from the field. According to results from the laboratory experiments, drainage water will probably need treatment for at least two-three decades after covering.
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| 9. |
- Travar, Igor, et al.
(författare)
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Environmental impact of ashes used in a landfill cover construction
- 2007
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Ingår i: SARDINIA 2007. - Cagliari : CISA, Environmental Sanitary Engineering Centre. - 9788862650038
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Konferensbidrag (refereegranskat)abstract
- Large amounts of construction materials will be needed both in Sweden and other European countries for capping landfills that will be closed in the near future. In order to reduce exploitation of virgin materials and to save natural resources, an option can be utilization of various types of secondary construction materials (SCM) e.g. ash, slag, sand from fluid bed incineration and compost. However, at the same time this may represent potential risks due to the release of trace elements and other pollutants into environment. The main aim of this work is to evaluate the environmental impact of water that discharges from different parts of a landfill cover built with ashes and other SCM.From 2003 to 2005, a four hectares large test area was established at Tveta landfill, southwest of Stockholm, Sweden. Test area is divided into six sub areas with regard to different recycled materials used in different layers of the cover construction (Figure 1).Figure 1. Design of the landfill cover test area at the Tveta landfill. BA = Bottom ash; FA = Fly ash; FC = Friedland clay Infiltrating water through the landfill cover either drains off in the drainage layer as drainage water or percolates through the liner into landfill body as leachate. At Tveta landfill, leachate amounts between 1 l (m2 yr)-1 and 30 l (m2 yr)-1 have been observed below highly compacted ash liner. Results show that leachate samples have higher pH, salt forming elements (e.g. K, Na, Ca and Cl) and concentrations of Cd, Ba As, Al, and Mo, and lower concentrations of Mn, Zn, Mg, Fe, Ni, and Pb compared to drainage water. The concentrations of Cr and total N are in the same range in leachate and drainage water while NH4-N is higher in leachate. Leachate of areas 1 and 4 shows higher content of organic matter than drainage water in these areas. A strong correlation is observed between EC, K, Na and Cl as well as between Cu and TOC. The comparison of the leachate and drainage water quality with different limit values showed that the leachate had elevated concentrations of As, Mo, Cl and nitrogen while the drainage water was mainly contaminated by Ni, Zn, Cl and nitrogen with the addition of As, Cu, Mo, and Pb in areas 2 and 4.Following conclusions can be drawn by now:The hydraulic properties of the landfill cover satisfy legislative requirements for non hazardous waste landfills; in some cases/areas also for hazardous waste landfills.Most of the infiltrating water through the landfill cover is discharged as drainage water. Thus, the design of layers above the liner is most important with regard to the environmental impact of the construction. Both leachate and drainage water need treatment before discharge into the local recipient. Organic matter in the protection layer is likely to contribute to the mobilization of Cu and Ni in short term.The sea might be a suitable recipient in cases where ashes are used in landfill covers because both leachate and drainage contain salt forming elements in elevated concentrations which may harm groundwater or freshwater but do not pose a risk to salt-water.The leaching of most pollutants did not show any clear tendencies during first three years. Thus, assessing the time period for treatment needs is difficult. However, it is expected that the contaminants in the drainage water will be depleted within few decades.Leachate might be contaminated by salt forming and trace elements for one hundred years. However, generated leachate amounts are low and it is expected that leachate from landfill cover will not influence overall landfill leachate with full extent.The ageing of the ashes in connection with mineral transformations is an important process that is expected to reduce the release of pollutants. Further research is needed with regard to long term changes of the material properties and the treatment needs for water.
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| 10. |
- Travar, Igor
(författare)
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Environmental impact of ashes used in a landfill cover construction
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The landfilling ban for combustible waste in EU countries and the extended use of bio fuels in heat and electricity production will result in an increasing generation of incineration residues, such as fly ash and bottom ash. Instead of landfilling, ashes used as a construction material in, e.g., roads or landfill covers can result in saving natural resources and economical advantages. The main aim of this work is to assess how ashes used in landfill cover construction affect the environment and how the potential environmental impact can be assessed. The main pollution pathway of using ashes in landfill cover construction is leaching. Laboratory leaching tests can be used as a tool to assess the possible environmental impact of ashes before their use in a landfill cover. Solubility leaching tests, e.g. batch leaching test, pH-stat test and percolation test, can be useful tools to predict contaminants that can be released from ashes used in a protection and drainage layer. The diffusion leaching test together with the availability test are suitable to assess the release from ash used as liner material. However, predicting contaminant release in the field is difficult due to the complexity of the processes occurring in the field. Leachate and drainage water are two types of water generated in landfill cover. Leachate samples were mainly contaminated by As, Mo, Cl and N. Drainage water contained high concentrations of Ni, Cl and N with the addition of As, Cu, Mo, Pb and Zn in the areas where bottom ash is in the protection layer. Since leaching of most pollutants showed no clear tendency to decline over time, assessing how long leachate and drainage water need treatment is difficult. However, it is expected that salt forming elements will be depleted from ashes within some decades. A lower release of other trace elements, such as Cu, Pb and Zn, to ash leachate is expected due to immobilization by Al/Fe hydr(oxides) and clay minerals.
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