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Strandberg, Anna, DrORCID iD iconorcid.org/0000-0003-0895-3474
Alternative names
Publications (10 of 24) Show all publications
Strandberg, A., Thyrel, M., Falk, J., Öhman, M. & Skoglund, N. (2024). Morphology and phosphate distribution in bottom ash particles from fixed-bed co-combustion of sewage sludge and two agricultural residues. Waste Management, 177, 56-65
Open this publication in new window or tab >>Morphology and phosphate distribution in bottom ash particles from fixed-bed co-combustion of sewage sludge and two agricultural residues
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2024 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 177, p. 56-65Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to provide detailed knowledge of the morphological properties of ash particles, including the volumetric fractions and 3D distributions of phosphates that lay within them. The ash particles came from digested sewage sludge co-combusted with K- and Si-rich wheat straw or K-rich sunflower husks. X-ray micro-tomography were combined with elemental composition and crystalline phase information to analyse the ash particles in 3D.

Analyses of differences in the X-ray attenuation enabled calculation of 3D phosphate distributions that showed high heterogeneity in the slag particles. This is underscored by a distinct absence of phosphates in iron-rich and silicon-rich parts. The slag from silicate-based wheat straw mixtures had lower average attenuation than that from sunflower husks mixtures, which contained more calcium. Calculated shares of phosphates between 7 and 17 vol% were obtained, where the highest value for a single assigned phosphate was observed in hard slag from wheat straw with 10 % sewage sludge. The porosity was notably higher for particles from pure wheat straw combustion (62 vol%), compared to the other samples (15–35 vol%). A high open pore volume fraction (60–97 vol%) indicates that a large part of the pores can be accessed by the surroundings. For all samples, more than 60 % of the discrete (closed) pores had an equivalent diameter < 30 μm, while the largest volume fraction consisted of pores with an equivalent diameter > 75 μm. Slag from sunflower husk mixtures had larger pore volumes and a greater relative number of discrete pores >75 µm compared to wheat straw mixtures.

Place, publisher, year, edition, pages
Elsevier, 2024
National Category
Agricultural Science
Identifiers
urn:nbn:se:umu:diva-221008 (URN)10.1016/j.wasman.2024.01.040 (DOI)38290348 (PubMedID)2-s2.0-85184148796 (Scopus ID)
Funder
The Royal Swedish Academy of Agriculture and Forestry (KSLA), GFS2018-0099Swedish Research Council, 2017-05331Bio4EnergySwedish Research Council Formas, 2018-00194Swedish Research Council Formas, 2017-01613
Available from: 2024-03-06 Created: 2024-03-06 Last updated: 2024-03-06Bibliographically approved
Skoglund, N., Thyrel, M., Perrin, J. & Strandberg, A. (2023). Characterisation of ash particles from co-combustion of bark and sludges from pulp and paper industry. Fuel, 340, Article ID 127597.
Open this publication in new window or tab >>Characterisation of ash particles from co-combustion of bark and sludges from pulp and paper industry
2023 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 340, article id 127597Article in journal (Refereed) Published
Abstract [en]

Recycling phosphorus from waste streams for fertilization purposes could contribute to a sustainable society. The production in the pulp and paper industry results in several waste streams, among others nutrient-rich sludges in different forms. This study presents a detailed chemical and 3D characterization of ash from co-combustion of bark and two types of sludges from a paper mill; mixed sludge and biosludge. The combustion performance was investigated for these experiments and advanced analysis methods were used to characterise the ashes to correlate chemical and physical properties relevant for nutrient recycling. The elemental composition was determined by energy-dispersive X-ray spectroscopy; dominating crystalline phases by X-ray diffraction; and morphology, porosity, pore size distribution and active surface area of the slag were analysed with synchrotron-based X-ray micro-tomography and image analysis. Slag was formed in all combustion experiments to a large extent with increasing amounts with a higher proportion of sludge. Nutrient amounts indicate that slag particles from co-combustion of both biosludge and mixed sludge can be useful either as a soil improvement directly or for recovery processes. Slag from combustion of 30 wt% biosludge and 70 wt% bark contained the highest amount of phosphorus, 9 at% on a C and O free basis. Evaluation of tomography data showed that discrete and open pores could be distinguished on a micrometre scale. The porosity of the slag varied between the replicates and fuel mixtures, on average between 17 and 23 vol% for the bark and sludge mixtures. Open pore volume displayed large variations, on average 39–56 vol% of the pores were open pores connected to the surrounding volume. For all samples, 90 % of the pores were small, with an equivalent diameter under 30 μm, but the largest pore volume (80–90 %) consists of pores with an equivalent diameter over 75 μm. In soils, pores with a minimum equivalent diameter over 30 μm generally transmit water and the smaller pores store water. The slag particles have relatively thick walls, with few pore openings to the surroundings, indicating that the slag needs to be pre-treated by milling or crushing before application in the soil.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Ash particle, Biosludge combustion, Micro-CT, Nutrient recycling, Synchrotron-based analysis, X-ray micro-tomography
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-204511 (URN)10.1016/j.fuel.2023.127597 (DOI)000926426100001 ()2-s2.0-85146730790 (Scopus ID)
Funder
EU, Horizon 2020, 637020–MOBILE FLIPBio4EnergySwedish Research Council, 2017-05331Swedish Research Council Formas, 2017- 01613
Available from: 2023-02-07 Created: 2023-02-07 Last updated: 2023-09-05Bibliographically approved
Strandberg, A., Steinvall, E., Morari, A. & Boman, C. (2023). Time-resolved understanding of the conversion of biochar and its properties during gasification. In: : . Paper presented at Nordic Flame Days 2023, Trondheim, Norway, 29-30 November, 2023.
Open this publication in new window or tab >>Time-resolved understanding of the conversion of biochar and its properties during gasification
2023 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Chemical Process Engineering Energy Engineering Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-219273 (URN)
Conference
Nordic Flame Days 2023, Trondheim, Norway, 29-30 November, 2023
Funder
ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 22-331J. Gust. Richert stiftelse, 2022-00816Bio4Energy, B4E3-FM-2-08
Available from: 2024-01-10 Created: 2024-01-10 Last updated: 2024-01-10Bibliographically approved
Strandberg, A., Skoglund, N. & Thyrel, M. (2021). Morphological characterisation of ash particles from co-combustion of sewage sludge and wheat straw with X-ray microtomography. Waste Management, 135, 30-39
Open this publication in new window or tab >>Morphological characterisation of ash particles from co-combustion of sewage sludge and wheat straw with X-ray microtomography
2021 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 135, p. 30-39Article in journal (Refereed) Published
Abstract [en]

Combustion of phosphorus-rich residual streams can produce nutrient-rich ashes and these can be used either in further processing or as materials for direct nutrient recycling. The latter requires knowledge on morphological parameters of such ash particles that may impact plant growth, nutrient availability, and soil physical properties. The present work aims to determine the porosity, pore size, and specific surface area of ash particles, and discuss these properties in light of literature concerning interaction with soil water and plant roots. Bottom ash particles from combustion of sewage sludge and wheat straw and their co-combustion were analysed with X-ray microtomography. Image analysis provided information on morphology, specific surface area, porosity, and pore structure on a micrometre scale resolution. Co-combusting sewage sludge with wheat straw resulted in differences in ash particles' porosity and pore structure compared to combustion of pure fuels. Pure wheat straw ash displayed 62 vol% porosity while there was no apparent difference between 10 wt% or 30 wt% mixtures of sewage sludge, with a porosity of 29–31 vol%. Open pore volume comprise the largest part of the porosity (72–99 vol%) enabling interaction between surrounding pore water and nutrients.

Overall, the ash particles display large open volume fractions and thin particle walls which may lead to rapid weathering and extensive interaction with soil water. The particles generally contained pore openings over 200 µm towards the surroundings, which provide opportunities for interaction with microbes and roots from a variety of plant species in addition to nutrient transport by soil water.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Ash particle, Micro-CT, Nutrient recycling, Porosity, Specific surface area
National Category
Soil Science Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-187222 (URN)10.1016/j.wasman.2021.08.019 (DOI)000700578500002 ()34461488 (PubMedID)2-s2.0-85113429007 (Scopus ID)
Funder
The Royal Swedish Academy of Agriculture and Forestry (KSLA), GFS2018-0099Swedish Research Council, 2017-05331Bio4EnergyThe Royal Swedish Academy of Sciences
Available from: 2021-09-07 Created: 2021-09-07 Last updated: 2022-12-07Bibliographically approved
Nordin, A., Strandberg, A., Elbashir, S., Åmand, L.-E., Skoglund, N. & Pettersson, A. (2020). Co-Combustion of Municipal Sewage Sludge and Biomass in a Grate Fired Boiler for Phosphorus Recovery in Bottom Ash. Energies, 13(7), Article ID 1708.
Open this publication in new window or tab >>Co-Combustion of Municipal Sewage Sludge and Biomass in a Grate Fired Boiler for Phosphorus Recovery in Bottom Ash
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2020 (English)In: Energies, E-ISSN 1996-1073, Vol. 13, no 7, article id 1708Article in journal (Refereed) Published
Abstract [en]

Phosphorus has been identified as a critical element by the European Union and recycling efforts are increasingly common. An important phosphorus-containing waste stream for recycling is municipal sewage sludge (MSS), which is used directly as fertilizer to farmland. However, it contains pollutants such as heavy metals, pharmaceutical residues, polychlorinated bi-phenyls (PCBs) and nano-plastics. The interest in combustion of MSS is continuously growing, as it both reduces the volume as well as destroys the organic materials and could separate certain heavy metals from the produced ashes. This results in ashes with a potential for either direct use as fertilizer or as a suitable feedstock for upgrading processes. The aim of this study was to investigate co-combustion of MSS and biomass to create a phosphorus-rich bottom ash with a low heavy metal content. A laboratory-scale fixed-bed reactor in addition to an 8 MWth grate-boiler was used for the experimental work. The concentration of phosphorus and selected heavy metals in the bottom ashes were compared to European Union regulation on fertilizers, ash application to Swedish forests and Swedish regulations on sewage sludge application to farmland. Element concentrations were determined by ICP-AES complemented by analysis of spatial distribution with SEM-EDS and XRD analysis to determine crystalline compounds. The results show that most of the phosphorus was retained in the bottom ash, corresponding to 9-16 wt.% P2O5, while the concentration of cadmium, mercury, lead and zinc was below the limits of the regulations. However, copper, chromium and nickel concentrations exceeded these standards.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
sewage sludge, grate boiler, heavy metals, phosphorus recovery, co-combustion
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-172844 (URN)10.3390/en13071708 (DOI)000537688400177 ()2-s2.0-85082858906 (Scopus ID)
Available from: 2020-06-26 Created: 2020-06-26 Last updated: 2023-08-28Bibliographically approved
Backman, M. B., Strandberg, A., Thyrel, M., Bergstrom, D. & Larsson, S. H. (2020). Does Mechanical Screening of Contaminated Forest Fuels Improve Ash Chemistry for Thermal Conversion?. Energy & Fuels, 34(12), 16294-16301
Open this publication in new window or tab >>Does Mechanical Screening of Contaminated Forest Fuels Improve Ash Chemistry for Thermal Conversion?
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2020 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 34, no 12, p. 16294-16301Article in journal (Refereed) Published
Abstract [en]

The effect of mechanical screening of severely contaminated forest fuel chips was investigated, focusing on main ash-forming elements and slagging tendency and other properties with relevance for thermal conversion. In this study, screening operations were performed according to practice on an industrial scale by combining a star screen and a supplementary windshifter in six different settings and combinations. Mechanical screening reduced the amount of ash and fine particles in the accept fraction. However, the mass losses for the different screening operations were substantial (20-50 wt %). Fuel analyses of the non-screened and the screened fuels showed that the most significant screening effect was a reduction of Si and Al, indicating an effective removal of sand and soil contaminations. However, the tested fuel's main ash-forming element's relative concentration did not indicate any improved combustion characteristics and ash-melting behavior. Samples of the accept fractions and non-screened material were combusted in a single-pellet thermogravimetric reactor, and the resulting ashes' morphology and elemental composition were analyzed by scanning electron microscopy-energy dispersive X-ray spectrometry and the crystalline phases by powder X-ray diffraction. Results from both these analyses confirmed that screening operations had no, or minor, effects on the fuels' ash chemistry and slagging tendencies, i.e., the fuels' proneness to ash melting was not improved. However, the reduction of ash and fine particles can reduce slagging and other operational problems in smaller and more sensitive combustion units.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2020
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-178552 (URN)10.1021/acs.energyfuels.0c03196 (DOI)000600407600092 ()2-s2.0-85096564275 (Scopus ID)
Available from: 2021-01-14 Created: 2021-01-14 Last updated: 2023-03-24Bibliographically approved
Strandberg, A., Carlborg, M., Boman, C. & Broström, M. (2019). Ash Transformation During Single-Pellet Combustion of a Silicon-Poor Woody Biomass. Energy & Fuels, 33(8), 7770-7777
Open this publication in new window or tab >>Ash Transformation During Single-Pellet Combustion of a Silicon-Poor Woody Biomass
2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 8, p. 7770-7777Article in journal (Refereed) Published
Abstract [en]

Biomass fuels with calcium and potassium as the main ash-forming elements are expected to form ash consisting mainly of carbonates and oxides. These carbonates are stable in a rather narrow temperature range, which in turn depends on the Ca/K ratio, as well as on the surrounding atmosphere. The objective of the present study was to perform a detailed characterization of ash formation and transformation at a single-pellet level during combustion of silicon-poor woody biomass fuel. Combustion tests were performed with poplar in a single-pellet isothermal thermogravimetric analyzer operated at different temperatures and atmospheres and quenched at different stages of fuel conversion. The char and residual ashes were characterized for morphology and chemical composition. The focus of the experimental work in this study was on the time (conversion) resolved ash formation and transformations at the late part of the char combustion phase. Thermodynamic equilibrium calculations were used both to design the experiments and to support the interpretation of experimental results. It was concluded that carbonates were, in general, stable at low temperatures (here, 600–800 °C), identified as CaCO3, K2Ca2(CO3)3, and K2Ca(CO3)2, and decomposed at higher temperatures. In addition, a combined carbonate and phosphate phase in the form of carbonate apatite, Ca9.9(PO4)6(CO3)0.9, was also found, mainly at lower temperatures. However, for char/ash samples quenched before full conversion, CaCO3 was still found at temperatures higher than expected, possibly explained by the stabilizing effect of locally higher CO2 partial pressure within the burning fuel particles. Thus, the results of the present study provide new insights into conversion-based ash formation and transformation in a burning fuel particle with relevance for combustion of Si-poor woody biomass fuels.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Bioenergy
Identifiers
urn:nbn:se:umu:diva-163274 (URN)10.1021/acs.energyfuels.9b00937 (DOI)000481569100090 ()2-s2.0-85070870382 (Scopus ID)
Projects
Bio4Energy
Funder
Bio4Energy
Available from: 2019-09-12 Created: 2019-09-12 Last updated: 2023-03-24Bibliographically approved
Strandberg, A., Skoglund, N. & Thyrel, M. (2019). Characterization of porosity and microstructure of phosphorus-rich ash particles with X-ray micro-tomography. In: : . Paper presented at Nordic Flame Days, Turku, Finland, 28-29 August, 2019.
Open this publication in new window or tab >>Characterization of porosity and microstructure of phosphorus-rich ash particles with X-ray micro-tomography
2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

A large proportion of the nutrients supplied from forest and agricultural sector are lost today, both through leaching and removing of produced biomass. Sustainable and efficient recycling of macro- and micro nutrients can be done by combustion / co-combustion of residual streams, which makes it possible to utilize for example the phosphorus-bound fraction in the produced ash for further processing and recycling. The porosity of the ash is important for, among other things, leaching and water-retaining ability when returning to the soil. The purpose of the project is to provide detailed knowledge of porosity and internal microstructure of ash particles from combustion of residual biomass streams, by using X-ray based micro-tomography and image analysis. The results provide new insights into how ash porosity and micro structure differs between different ashes, depending on fuel and the choice of conversion process.

National Category
Chemical Sciences Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-163277 (URN)
Conference
Nordic Flame Days, Turku, Finland, 28-29 August, 2019
Available from: 2019-09-12 Created: 2019-09-12 Last updated: 2019-10-23Bibliographically approved
Bozaghian Bäckman, M., Strandberg, A., De La Fuente, T., Karjalainen, M., Skoglund, N., Thyrel, M., . . . Larsson, S. H. (2019). Does mechanical screening improve fuel properties?: Effects of mechanical screening of stored logging residue chips on ash chemistry and other parameters relevant for combustion. In: : . Paper presented at EUBCE 2019: 27th European Biomass Conference and Exhibition, Lisbon, Portugal, May 27-30, 2019.
Open this publication in new window or tab >>Does mechanical screening improve fuel properties?: Effects of mechanical screening of stored logging residue chips on ash chemistry and other parameters relevant for combustion
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2019 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Bioenergy
Identifiers
urn:nbn:se:umu:diva-198464 (URN)
Conference
EUBCE 2019: 27th European Biomass Conference and Exhibition, Lisbon, Portugal, May 27-30, 2019
Available from: 2022-08-05 Created: 2022-08-05 Last updated: 2023-03-01Bibliographically approved
Skoglund, N., Strandberg, A., Öhman, M. & Boström, D. (2019). Elemental approaches to additives: mechanisms and dosage. In: : . Paper presented at World Sustainable Energy Days, REFAWOOD workshop session, 28 February, 2019, Wels, Austria.
Open this publication in new window or tab >>Elemental approaches to additives: mechanisms and dosage
2019 (English)Conference paper, Oral presentation only (Other academic)
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-157287 (URN)
Conference
World Sustainable Energy Days, REFAWOOD workshop session, 28 February, 2019, Wels, Austria
Note

Funded by the ERA-NET project REFAWOOD

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2020-02-24Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0895-3474

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