| 1. |
- Kumpiene, Jurate, et al.
(författare)
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Phosphorus and cadmium availability in soil fertilized with biosolids and ashes
- 2016
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 151, s. 124-132
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Tidskriftsartikel (refereegranskat)abstract
- The recycling of hygienized municipal sewage sludge (biosolids) to soil as the source of phosphorus (P) is generally encouraged. The use of biosolids, however, has some concerns, such as the presence of elevated concentrations of potentially toxic trace elements, and the possible presence of pathogens, hormones and antibiotics. Organic substances are destroyed during combustion whereas trace elements could partly be separated from P in different ash fractions. Biomass combustion waste (ash) can instead be considered as an alternative P source. This study evaluates and compares the impact of biosolids and their combustion residues (ashes), when used as fertilizers, on P and Cd solubility in soil, plant growth and plant uptake of these elements. Biosolids were also amended with K and Ca to improve the composition and properties of P in ashes, and incinerated at either 800 °C or 950 °C. Combustion of biosolids improved the Cd/P ratio in ashes by 2–5 times, compared with the initial biosolids. The low Cd content in ashes (4–9 mg Cd (kg P)−1) makes this material a particularly attractive alternative to mineral fertilizers. Significantly higher pore water P (as well as total N) was measured in soils containing biosolids, but plants produced a higher biomass in soil fertilized with ashes. The K and Ca amendments prior to biosolids combustion generally decreased the total Cd in ash, but had little effect on P and Cd uptake and biomass growth. Similarly, the combustion temperature had negligible effect on these factors as well.
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| 2. |
- Brännvall, Evelina
(författare)
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Accelerate ageing of refuse-derived-fuel (RDF) fly ashes
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ashes have properties that can be exploited in various applications, e.g. some ashes can be used in the construction of barriers in a landfill final top cover. A landfill top cover is a multilayer construction that protects the environment in several ways, for instance hindering gas emissions from the landfill body and water infiltration into the waste.Impervious natural materials like clay, synthetic materials like geomembranes or bentonite carpets, geosynthetic clay liners or combinations of such materials are commonly used in landfill top cover constructions. Since differential settlement may occur and the lifetimes of the synthetic materials are uncertain, it is advantageous to use thick mineral constructions. There is a great need for these materials, and substantial savings of resources can be made if alternative waste materials, like ashes, are used. Currently, ashes are either landfilled or used as construction materials. They are subject to weathering processes, including physical, chemical and mineralogical changes caused (inter alia) by fluctuations of temperature and humidity, atmospheric gases or acid rain. Ashes contain various potentially hazardous and non-hazardous chemical compounds. Therefore, precautions must be taken to avoid leaching of substances such as heavy metals into the surrounding environment. Mineral phases that are initially present and/or that form during the ageing are primarily responsible for the immobilization or leaching of diverse metals and salts. Newly formed mineral phases like clay minerals are of main interest, because of their very high cation exchange capacity, swelling and expansion properties.The conditions found in a landfill environment are likely to favour clay mineral formation. This thesis 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 mineralogical 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 their acid neutralization capacity (ANC) and leaching behaviour.Minerals (ettringite and hydrocalumite) promoting the immobilization of hazardous compounds were found in both fresh ash and ash aged under atmospheric conditions, but these minerals disappeared upon carbonation. The main phases in ash at 20% and 100% CO2 were calcite, gypsum/anhydrite and vaterite. The abundance of gypsum and anhydrite was directly related to the temperature at which ashes were aged. The major mineral phases detected in ashes aged under 20% CO2, 65% RH and 30°C (corresponding to conditions generally found in a landfill cover) were calcite and gypsum/bassanite. 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, consequently 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. No clay minerals were detected by XRD and SEM analysis in either fresh or aged ashes. However, geochemical modelling indicated that such minerals may precipitate. The modelling also indicated that clay minerals like saponite, vermiculite, chrysotile and hydrotalcite were likely to precipitate in most leachates from ash aged for 3, 10 and 22 months. Smectite, montmorillonite and illite may precipitate in leachates of ash aged for 31 months. The formation of smectite, montmorillonite and vermiculite would be advantageous due to their very high cation exchange capacities, which would favour the stabilization/immobilization of heavy metals in the mineral phases.
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| 3. |
- 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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| 4. |
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| 5. |
- Brännvall, Evelina, et al.
(författare)
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Changes of fly ash properties during the ageing
- 2015
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Ingår i: Journal of environmental engineering. - 0733-9372 .- 1943-7870. ; 141:5
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Tidskriftsartikel (refereegranskat)abstract
- Aging of refuse-derived fuel (RDF) fly ashes was investigated in a long-term laboratory experiment. Aging affected the chemical stability of RDF fly ash in terms of leaching behavior, ANC, and mineralogical transformations. The design of experiment model evaluation showed that the use of RDF ashes in a top cover liner construction has the following advantages: most of the investigated hazardous elements like Pb, Cl, Cr, Cu, etc., will not be released from the ashes, and their buffer capacity will increase with time. However, aging has the disadvantage that leaching of Zn and SO 4 is likely to increase. The multivariate data analysis of the coefficients of variation did not reveal any systematic errors in the performance of the experiment. However, batch leaching test not always reflect the real situation in the landfill top cover environment.
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| 6. |
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| 7. |
- Brännvall, Evelina, et al.
(författare)
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Effect of industrial residue combinations on availability of elements
- 2014
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 276, s. 171-181
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Tidskriftsartikel (refereegranskat)abstract
- Industrial residues, such as fly ashes and biosolids, contain elements (e.g. N, P, K, S, Ca and Zn) that make them a viable alternative for synthetic fertilizers in forestry and agriculture. However, the use of these materials is often limited due to the presence of potentially toxic substances. It is therefore necessary to assess and, when warranted, modify the chemical and physical form of these and similar waste materials before any advantages are taken of their beneficial properties. Biofuel fly ash, municipal solid waste incineration (MSWI) fly ash, biosolids, peat, peat residues and gypsum board waste were combined in various proportions, and this resulted in increased leaching of N, P, S, Cu and Mn, but decreased leaching of Ca, K, Mg, Cr, Fe, Ni, Zn, Al, As and Pb. Chemical fractionation revealed that elements Ca, K, Mg, S and Mn were predominantly exchangeable, while the rest of the elements were less mobile. Cadmium was mostly exchangeable in MSWI fly ash, but less mobile in biofuel fly ash mixtures. Recycling of MSWI fly ash in the mixtures with fertilizers is considerably less attractive, due to the high levels of salts and exchangeable Cd.
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| 8. |
- Brännvall, Evelina, et al.
(författare)
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Effect of residue combinations on plant uptake of nutrients and potentially toxic elements
- 2014
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 132, s. 287-295
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the plant pot experiment was to evaluate potential environmental impacts of combined industrial residues to be used as soil fertilisers by analysing i) element availability in fly ash and biosolids mixed with soil both individual and in combination, ii) changes in element phytoavailability in soil fertilised with these materials and iii) impact of the fertilisers on plant growth and element uptake.Plant pot experiments were carried out, using soil to which fresh residue mixtures had been added. The results showed that element availability did not correlate with plant growth in the fertilised soil with. The largest concentrations of K (3534mg/l), Mg (184mg/l), P (1.8mg/l), S (760mg/l), Cu (0.39mg/l) and Zn (0.58mg/l) in soil pore water were found in the soil mixture with biosolids and MSWI fly ashes; however plants did not grow at all in mixtures containing the latter, most likely due to the high concentration of chlorides (82g/kg in the leachate) in this ash. It is known that high salinity of soil can reduce germination by e.g. limiting water absorption by the seeds. The concentrations of As, Cd and Pb in grown plants were negligible in most of the soils and were below the instrument detection limit values.The proportions of biofuel fly ash and biosolids can be adjusted in order to balance the amount and availability of macronutrients, while the possible increase of potentially toxic elements in biomass is negligible seeing as the plant uptake of such elements was low. © 2013 Elsevier Ltd.
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| 9. |
- Brännvall, Evelina, et al.
(författare)
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Elements availability in soil fertilized with pelletized fly ash and biosolids
- 2015
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 159, s. 27-36
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to evaluate the impact of combined and pelletized industrial residues on availability and mobility of nutrients and potentially toxic elements in soil, plant growth and element uptake. Plant pot experiments were carried out using soil to which 2% of pelletized residue containing biosolids mixed with either municipal solid waste incineration fly ash (MFA) or biofuel fly ash (BFA) was added. The tests showed that the plant growth did not correspond to the content of available nutrients in fertilised soil. MFA application to soil resulted in elevated concentrations of P (506 mg/kg), As (2.7 mg/kg), Cd (0.8 mg/kg) and Pb (12.1 mg/kg) in soil, lower plant uptake of Al (25 mg/kg) and Ba (51 mg/kg), but higher accumulation of As (4.3 mg/kg) and Cd (0.3 mg/kg) in plants compared to the unamended soil and soil amended with BFA. On average, the biomass of the plants grown in the soil containing MFA was larger than in other soils.Considering the use of industrial residue mixtures as soil amendments or fertilizers, the amount of added elements should not exceed those taken up by plants, by this preventing the increase of soil background concentrations.
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| 10. |
- Brännvall, Evelina, et al.
(författare)
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Factors influencing chemical and mineralogical changes in RDF fly ashes during aging
- 2014
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Ingår i: Journal of environmental engineering. - 0733-9372 .- 1943-7870. ; 140:3
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Tidskriftsartikel (refereegranskat)abstract
- The effects of aging should be considered for reliable long-term assessments of the environmental risks of the use of refuse-derived-fuel (RDF) fly ash as landfill top cover liner material. Mineral transformations that occur in RDF fly ash, and the effects of selected factors on these transformations, were studied on compacted fly ash specimens in an accelerated aging experiment using a reduced factorial design. Carbon dioxide concentration, temperature, relative air humidity, time, and the quality of added water were varied in six factor combinations. Acid neutralization capacity and leaching behavior were analyzed after four different periods of time. The results were evaluated with multivariate data analysis. A significant change in the acid neutralization capacity, a decrease in leaching of Ba, Ca, Cl − , Cr, Cu, Pb, K, and Na, and an increase in solubility of Mg, Si, Zn, and SO 2− 4 could be attributed to different aging conditions
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