| 1. |
- Arm, Maria, et al.
(författare)
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Pulp mill fly ash for stabilization of low-volume unpaved forest roads — field performance
- 2014
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Ingår i: Canadian journal of civil engineering (Print). - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 41:11, s. 955-963
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Tidskriftsartikel (refereegranskat)abstract
- Increased temperatures and rainfalls will give more settlements and less bearing capacity in gravel roads, which will have implications for the forestry. Pulp mill fly ash without additives was used for stabilizing the road base of a low-volume gravel road. A two-year monitoring of the road was conducted, including measurements of achieved ash content, density, water infiltration capacity, and load bearing capacity. The results showed that the ash-stabilized sections performed better than conventionally upgraded sections and also achieved increased bearing capacity over time. Hydration of the fly ash increased the stiffness and decreased the permeability of the road base. The differences were more pronounced during spring thaw. Best performance was achieved in the section with thicker ash stabilized layer.
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| 2. |
- Kumpiene, Jurate, et al.
(författare)
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Carbon speciation in ash, residual waste and contaminated soil by thermal and chemical analyses
- 2011
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 31:1, s. 18-25
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Tidskriftsartikel (refereegranskat)abstract
- Carbon in waste can occur as inorganic (IC), organic (OC) and elemental carbon (EC) each having distinct chemical properties and possible environmental effects. In this study, carbon speciation was performed using thermogravimetric analysis (TGA), chemical degradation tests and the standard total organic carbon (TOC) measurement procedures in three types of waste materials (bottom ash, residual waste and contaminated soil). Over 50% of the total carbon (TC) in all studied materials (72% in ash and residual waste, and 59% in soil) was biologically non-reactive or EC as determined by thermogravimetric analyses. The speciation of TOC by chemical degradation also showed a presence of a non-degradable C fraction in all materials (60% of TOC in ash, 30% in residual waste and 13% in soil), though in smaller amounts than those determined by TGA. In principle, chemical degradation method can give an indication of the presence of potentially inert C in various waste materials, while TGA is a more precise technique for C speciation, given that waste-specific method adjustments are made. The standard TOC measurement yields exaggerated estimates of organic carbon and may therefore overestimate the potential environmental impacts (e.g. landfill gas generation) of waste materials in a landfill environment.
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| 3. |
- Kumpiene, Jurate, et al.
(författare)
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Leaching of arsenic, copper and chromium from thermally treated soil
- 2016
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 183:3, s. 460-466
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Tidskriftsartikel (refereegranskat)abstract
- Thermal treatment, if properly performed, is an effective way of destroying organic compounds in contaminated soil, while impact on co-present inorganic contaminants varies depending on the element. Leaching of trace elements in thermally treated soil can be altered by co-combusting different types of materials. This study aimed at assessing changes in mobility of As, Cr and Cu in thermally treated soil as affected by addition of industrial by-products prior to soil combustion. Contaminated soil was mixed with either waste of gypsum boards, a steel processing residue (Fe3O4), fly ash from wood and coal combustion or a steel abrasive (96.5% Fe0). The mixes and unamended soil were thermally treated at 800 °C and divided into a fine fraction <0.125 mm and a coarse fraction >0.125 mm to simulate particle separation occurring in thermal treatment plants. The impact of the treatment on element behaviour was assessed by a batch leaching test, X-ray absorption spectroscopy and dispersive X-ray spectrometry. The results suggest that thermal treatment is highly unfavourable for As contaminated soils as it increased both the As leaching in the fine particle size fraction and the mass of the fines (up to 92%). Soil amendment with Fe-containing compounds prior to the thermal treatment reduced As leaching to the levels acceptable for hazardous waste landfills, but only in the coarse fraction, which does not justify the usefulness of such treatment. Among the amendments used, gypsum most effectively reduced leaching of Cr and Cu in thermally treated soil and could be recommended for soils that do not contain As. Fly ash was the least effective amendment as it increased leaching of both Cr and As in majority of samples.
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| 4. |
- Kumpiene, Jurate, et al.
(författare)
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Minskad mängd organiskt avfall på deponi : Effekt på redox-förhållanden, nedbrytning av organiskt material och utlakning av redox-känsliga ämnen
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I den nya EU-lagstiftningen angående deponering av avfall (2003/33/EC) finns krav på att den totala organiska halten kol (TOC) i avfall inte bör överstiga 3% för inert avfall, 5% för icke farligt avfall, 6% för farligt avfall och 18% för restprodukter från avfallsförbränning, vilket innebär en sänkning av tidigare gränsvärden. Förändringen kan få konsekvenser för bland annat mobiliteten hos redox-känsliga ämnen. Vid analys av TOC enligt europeisk och svensk standard (EN 13 137) går det inte att särskilja mellan organiskt kol och elementärt kol vilket är ett problem eftersom elementärt kol är inert i deponeringssammanhang. Genom biologiska, kemiska och termogravimetriska analyser har det här projektet försökt ge svar på hur stor andel av TOC som motsvaras av organiskt, lätt nedbrytbart kol och hur stor effekt halten organiskt material har på utlakningen av redox-känsliga ämnen från avfall. Tre olika avfall har ingått i undersökningen och som representerar aktuella avfallsströmmar till svenska upplag: en CCAförorenad jord, en bottenaska från biobränsleförbränning och ett restavfall. Nedbrytningen av organiskt material i avfallen och dess inverkan på utlakningen av redoxkänsliga ämnen har studerats i laboratorieförsök med metoder som BMP-försök (metanbildningspotential vid nedbrytning av organiskt material) och olika laktest i oxiderad och reducerad miljö, med och utan tillsats av organiskt material. Kolspeciering har gjorts dels med standardiserade analysmetoder för TOC men också med termogravimetrisk (TG) analys kopplad till differentiell termisk analys (DTA) och quadrupole masspektrometri (QMS). Resultaten från kolspecieringen med TG-analys visar på att den dominerade andelen kol i samtliga avfall var elementärt kol (ca 60%) medan standardiserad TOC-analys visar på att allt kol i askan och jorden var organiskt. Kolinnehållet i restfraktionen varierade stort och gav inga signifikanta skillnader mellan totalt och organiskt kol. Bestämningen av TOC, med standardiserad metod, i jorden och askan gav signifikant högre värden än analys med TG. Restfaktionen uppvisade ingen signifikant skillnad mellan de båda metoderna. Restfraktionen uppvisade den högsta gasbildningspotentialen medan nedbrytningen av organiskt material i askor kan vara svår att bedöma med biologiska metoder på grund av karbonatiseringsreaktioner i materialet. Utlakningen av redox-känsliga ämnen påverkades av mängden reaktivt organiskt material. En hög halt organiskt material sänkte redoxpotentialen i avfallen och krom och koppa visade på en minskad utlakning i reducerade miljö i samtliga avfall, zink även i jorden och restfaktionen. Utlakningen av arsenik och bly ökade i reducerande miljö från samtliga avfall. Från askan ökade också utlakningen av zink. Generellt ökar utlakningen av ämnen som till största delen är bundna till reducerbart material (t.ex. Fe-Mn-oxider) vid en högre halt organiskt material, medan det omvända gäller för ämnen som till största delen är bundna till oxiderbart material (organiskt material och sulfider). Andra faktorer som inverkar på mobiliteten hos kritiska ämnen är faktorer som pH och närvaron av ligander. Även materialens fysiska egenskaper som porositet och permeabilitet måste vägas in vid en bedömning av ändrad avfallssammansättnings effekt på utlakningen från deponier.
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| 5. |
- Kumpiene, Jurate, et al.
(författare)
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Remediation of soil contaminated with organic and inorganic wood impregnation chemicals by soil washing
- 2017
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 184, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the efficiency of a large scale washing/wet sieving technique for a soil contaminated with wood impregnation chemicals by 1) defining the final distribution of trace elements (As, Cu, Cr, Zn) and polycyclic aromatic hydrocarbons (PAH) in separated soil particle size fractions; and 2) defining the leaching behavior of the contaminants in these soil fractions. A soil washing experiment was implemented at waste management facility in Sweden using a full scale soil sorting and washing equipment. Five tons of soil was loaded to the equipment and wet-sieved into the following fractions: >16 mm, 8–16 mm, 2–8 mm, 0.2–2 mm, <0.2 mm and a fraction that floated on top of the slurry before the final separation phase, composed of organic matter (OM). Analysis of total concentrations of contaminants in all soil fractions indicated that wet sieving/soil washing was not efficient to reduce the total volume of soil that needs further treatment. Even the coarsest soil fractions (>8 mm) contained elevated concentrations of total As and PAH. Leaching of As from all washed soil fractions was so high, that none of the particle size fractions could be disposed of without additional treatment.
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| 6. |
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| 7. |
- Nordmark, Désirée
(författare)
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Assessment of thermal treatment of trace element contaminated soil
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many contaminated sites in Sweden are characterised by a complex contamination situation with a mixture of organic and inorganic contaminants. For example, wood preservation with creosote, pentachlorophenol and chromated copper arsenate (CCA) has caused this kind of co-contaminated sites. Generally, stepwise remediation has to be used for remediation of these sites with separation and destruction of the organic contaminants and concentration, separation and stabilization of the inorganic contaminants during separate treatment steps. Thermal treatment methods are suitable for the destruction of organics but can increase the mobility of some inorganic contaminants due to phase transitions in the soil minerals. These changes have to be considered during further handling of the soil. In this work, the effects of thermal treatment on the mobility of CCA and critical factors affecting the mobility were studied. Also, different types of thermal treatment methods suitable for remediation of wood preservatives are discussed. The study included laboratory tests and a literature study. A CCA- contaminated soil was separated in four particle size fractions and thermally treated at 800 °C. Batch leaching tests showed that the thermal treatment increased the leaching of As and Cr while the leaching of Cu decreased. A chemical sequential extraction test indicated that the enhanced As leaching probably depended on the reduction of available adsorption sites for trace elements in the soil, due to crystallisation of Fe oxides. The enhanced leaching of Cr could be explained by a minor increase of easily soluble Cr(VI), an increase of the pH, and the competition for sorption sites with other oxyanions. However, the amount of stable Cr species increased during the thermal treatment. The reduced leaching of Cu could be explained by the formation of stable Cu species. The volatility of trace elements is positively correlated to treatment time and temperature. Arsenic is relatively volatile while Cr and Cu are not, although chlorides in the soil enhance Cu volatility. Thermal treatment in a reducing atmosphere enhances the volatility of As. Thermal treatment techniques are divided in extraction/desorption techniques (100-800 °C) and incineration techniques (800-1400 °C). Because of the high energy demand, incineration is most beneficial for smaller quantities of soil. Thermal desorption techniques imply an after treatment of the volatilized organic contaminants: they are combusted in an afterburner, condensed, or collected in a filter. An effective air pollution control (APC) system is necessary in order to control the volatile emissions. In rotary dryer/kiln facilities particles < 0.075 mm are transferred to cyclones and bag filters causing pressure drops and build-up problems. For the treatment of trace element contaminated soil this fact could be beneficial, because the highly contaminated fine fraction of the soil can be handled separately subsequently. Although a low temperature is beneficial to control the volatility of trace elements, it is not always the best choice concerning the leaching, because some trace elements have their leaching maxima after thermal treatment at 200-400 °C. The concentration and mobility of trace elements in the treated soil is controlled by factors such as chemical speciation of the trace elements, interactions between trace elements and soil constituents and process parameters such as fuel, atmosphere, treatment temperature and time. Stabilizing amendments mixed in the soil before thermal treatment could probably reduce the mobility of trace elements and should be investigated further.
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| 8. |
- Nordmark, Desiree, et al.
(författare)
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Changes in leaching and chemical fractionation of arsenic, chromium and copper in soil after thermal treatment
- 2009
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Ingår i: SARDINIA 2009. - Cagliari : CISA, Environmental Sanitary Engineering Centre. - 9788862650076
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Konferensbidrag (refereegranskat)abstract
- Thermal treatment is used for remediation of soils contaminated with both organic and inorganic contaminants. The target is destruction of organic contaminants while the residue containing the inorganic contaminants has to be further treated. The effects of thermal treatment on As, Cr and Cu in contaminated soil are evaluated in laboratory and field tests, using leaching test, As speciation and sequential extraction test. In laboratory tests on four particle size fractions, the leaching of As and Cr increased by factors of 18-40 and 2-23, respectively, while the mobility of Cu decreased 12-4 fold after thermal treatment. The concentration of As(V) in the finest soil fraction increased 19 fold, while As(III) remained constant. Arsenic, Cr and Cu associated to the reducible soil fraction decreased, possibly due to enhanced crystallisation of Fe oxides and reduction of available adsorption sites. In the field test, the concentration of As, Cr and Cu was 1-4 times higher in the filter fraction compared to the treated soil.
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| 9. |
- Nordmark, Désirée, et al.
(författare)
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Controlling the mobility of chromium and molybdenum in MSWI fly ash in a washing process
- 2018
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 76, s. 727-733
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Tidskriftsartikel (refereegranskat)abstract
- Fly ash from a cogeneration plant near Sundsvall in Sweden was treated in an ash-washing facility. The leaching of chromium (Cr) and molybdenum (Mo) from the ash residue exceeded the limit values for non-hazardous landfills. In this study factors that influence the leaching of Cr and Mo were identified and methods that can reduce the leaching were evaluated. The results revealed that the mobility of Cr and Mo are mainly controlled by pH and redox reactions and sequential extraction tests also showed that the fraction of highly soluble species of Cr and Mo increased after washing due to pH reactions in the ash during the process. Stabilization of the pH at ∼8 through carbonation of the washed ash and a lowering of the redox potential by adding ferrous iron to the process resulted in decreased leaching. Treatment with carbon dioxide yielded a decrease (from 10.7 to 8.2) in the pH and, hence, the leaching of Cr and Mo by 93 and 91%, respectively. And the addition of ferrous iron reduced the leaching of Cr by 50%. Carbonation of the ash can be achieved via treatment with flue gases from the power plant or treatment with landfill gas at the disposal site.
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| 10. |
- Nordmark, Desiree, et al.
(författare)
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Environmental and mechanical assessment of wood fly ash used for stabilisation of gravel roads
- 2011
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Ingår i: SARDINIA 2011. - Cagliari : CISA Publisher, Italy.
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Konferensbidrag (refereegranskat)abstract
- Due to climate change, there is a growing demand for mechanically stabilising forestry roads in Sweden. One way to do this is by addition of cement to the bearing layer of the road. In this study, cement was replaced by a forestry industry fly ash. Mechanical testing showed that a good stabilising effect could be achieved and at a 30% ash addition, it could resist more than 12 freeze-thaw cycles. The environmental impact of the ash addition was assessed using a standard leaching test at a liquid to solid ration of ten. The results indicated that most constituents of the ash remained fairly stable, but that notably chloride, potassium, calcium and sodium was mobilised in the grams per kg of TS range, adding up to about 1 % of the total mass. This may cause an elevated salinity in the emediate vicinity of a road, e g in the ditches, under a short time period, but is not considered to be a major problem for recipients. The results also indicate that the total content is a poor estimate for the leachability of various elements.
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