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  • 1. Avagyan, Rozanna
    et al.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Westerholm, Roger
    Determination of hydroxylated polycyclic aromatic hydrocarbons by HPLC-photoionization tandem mass spectrometry in wood smoke particles and soil samples2015In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 407, no 16, p. 4523-4534Article in journal (Refereed)
    Abstract [en]

    A simple and fast method for analysis of hydroxylated polycyclic aromatic hydrocarbons using pressurized liquid extraction and high performance liquid chromatography utilizing photoionization tandem mass spectrometry was developed. Simultaneous separation and determination of nine hydroxylated polycyclic aromatic hydrocarbons and two hydroxy biphenyls could be performed in negative mode with a run time of 12 min, including equilibration in 5 min. The calibration curves were in two concentration ranges; 1-50 ng/mL and 0.01-50 mu g/mL, with coefficients of correlation R (2) > 0.997. The limits of detection and method quantification limits were in the range of 9-56 pg and 5-38 ng/g, respectively. A two-level full factorial experimental design was used for screening of conditions with the highest impact on the extraction. The extraction procedure was automated and suitable for a large number of samples. The extraction recoveries ranged from 70 to 102 % and the matrix effects were between 92 and 104 %. The overall method was demonstrated on wood smoke particles and soil samples with good analytical performance, and five OH-PAHs were determined in the concentration range of 0.19-210 mu g/g. As far as we know, hydroxylated polycyclic aromatic hydrocarbons were determined in wood smoke and soil samples using photoionization mass spectrometry for the first time in this present study. Accordingly, this study shows that high performance liquid chromatography photoionization tandem mass spectrometry can be a good option for the determination of hydroxylated polycyclic aromatic hydrocarbons in complex environmental samples.

  • 2. Avagyan, Rozanna
    et al.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Westerholm, Roger
    Particulate hydroxy-PAH emissions from a residential wood log stove using different fuels and burning conditions2016In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 140, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Hydroxylated polycyclic aromatic hydrocarbons are oxidation products of polycyclic aromatic hydrocarbons, but have not been studied as extensively as polycyclic aromatic hydrocarbons. Several studies have however shown that hydroxylated polycyclic aromatic hydrocarbons have toxic and carcinogenic properties. They have been detected in air samples in semi urban areas and combustion is assumed to be the primary source of those compounds. To better understand the formation and occurrence of particulate hydroxylated polycyclic aromatic hydrocarbons from residential wood log stove combustion, 9 hydroxylated polycyclic aromatic hydrocarbons and 2 hydroxy biphenyls were quantified in particles generated from four different types of wood logs (birch, spruce, pine, aspen) and two different combustion conditions (nominal and high burn rate). A previously developed method utilizing liquid chromatography photo ionization tandem mass spectrometry and pressurized liquid extraction was used. Polycyclic aromatic hydrocarbons were analyzed along with hydroxylated polycyclic aromatic hydrocarbons. The hydroxylated polycyclic aromatic hydrocarbon emissions varied significantly across different wood types and burning conditions; the highest emissions for nominal burn rate were from spruce and for high burn rate from pine burning. Emissions from nominal burn rate corresponded on average to 15% of the emissions from high burn rate, with average emissions of 218 mu g/MJ(fuel) and 32.5 mu g/MJ(fuel) for high burn rate and nominal burn rate, respectively. Emissions of the measured hydroxylated polycyclic aromatic hydrocarbons corresponded on average to 28% of polycyclic aromatic hydrocarbons emissions. This study shows that wood combustion is a large emission source of hydroxylated polycyclic aromatic hydrocarbons and that not only combustion conditions, but also wood type influences the emissions of hydroxylated polycyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons. There are few studies that have determined hydroxylated polycyclic aromatic hydrocarbons in emissions from wood combustion, and it is therefore necessary to further investigate the formation, occurrence and distribution of these compounds as they are present in significant amounts in wood smoke particles.

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  • 3.
    Barath, Stefan
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Mills, Nicholas L
    Lundbäck, Magnus
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Törnqvist, Håkan
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Lucking, Andrew J
    Langrish, Jeremy P
    Söderberg, Stefan
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Westerholm, Roger
    Löndahl, Jakob
    Donaldson, Ken
    Mudway, Ian S
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Newby, David E
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Impaired vascular function after exposure to diesel exhaust generated at urban transient running conditions2010In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 7, no 1, p. 19-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Traffic emissions including diesel engine exhaust are associated with increased respiratory and cardiovascular morbidity and mortality. Controlled human exposure studies have demonstrated impaired vascular function after inhalation of exhaust generated by a diesel engine under idling conditions.

    OBJECTIVES: To assess the vascular and fibrinolytic effects of exposure to diesel exhaust generated during urban-cycle running conditions that mimic ambient 'real-world' exposures.

    METHODS: In a randomised double-blind crossover study, eighteen healthy male volunteers were exposed to diesel exhaust (approximately 250 mug/m3) or filtered air for one hour during intermittent exercise. Diesel exhaust was generated during the urban part of the standardized European Transient Cycle. Six hours post-exposure, vascular vasomotor and fibrinolytic function was assessed during venous occlusion plethysmography with intra-arterial agonist infusions.

    MEASUREMENTS AND MAIN RESULTS: Forearm blood flow increased in a dose-dependent manner with both endothelial-dependent (acetylcholine and bradykinin) and endothelial-independent (sodium nitroprusside and verapamil) vasodilators. Diesel exhaust exposure attenuated the vasodilatation to acetylcholine (P < 0.001), bradykinin (P < 0.05), sodium nitroprusside (P < 0.05) and verapamil (P < 0.001). In addition, the net release of tissue plasminogen activator during bradykinin infusion was impaired following diesel exhaust exposure (P < 0.05).

    CONCLUSION: Exposure to diesel exhaust generated under transient running conditions, as a relevant model of urban air pollution, impairs vasomotor function and endogenous fibrinolysis in a similar way as exposure to diesel exhaust generated at idling. This indicates that adverse vascular effects of diesel exhaust inhalation occur over different running conditions with varying exhaust composition and concentrations as well as physicochemical particle properties. Importantly, exposure to diesel exhaust under ETC conditions was also associated with a novel finding of impaired of calcium channel-dependent vasomotor function. This implies that certain cardiovascular endpoints seem to be related to general diesel exhaust properties, whereas the novel calcium flux-related effect may be associated with exhaust properties more specific for the ETC condition, for example a higher content of diesel soot particles along with their adsorbed organic compounds.

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  • 4. Bolling, Anette Kocbach
    et al.
    Pagels, Joakim
    Yttri, Karl Espen
    Barregard, Lars
    Sallsten, Gerd
    Schwarze, Per E
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Health effects of residential wood smoke particles: the importance of combustion conditions and physicochemical particle properties2009In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 6, article id 29Article, review/survey (Refereed)
    Abstract [en]

    Background: Residential wood combustion is now recognized as a major particle source in many developed countries, and the number of studies investigating the negative health effects associated with wood smoke exposure is currently increasing. The combustion appliances in use today provide highly variable combustion conditions resulting in large variations in the physicochemical characteristics of the emitted particles. These differences in physicochemical properties are likely to influence the biological effects induced by the wood smoke particles.

    Outline: The focus of this review is to discuss the present knowledge on physicochemical properties of wood smoke particles from different combustion conditions in relation to wood smoke-induced health effects. In addition, the human wood smoke exposure in developed countries is explored in order to identify the particle characteristics that are relevant for experimental studies of wood smoke-induced health effects. Finally, recent experimental studies regarding wood smoke exposure are discussed with respect to the applied combustion conditions and particle properties.

    Conclusion: Overall, the reviewed literature regarding the physicochemical properties of wood smoke particles provides a relatively clear picture of how these properties vary with the combustion conditions, whereas particle emissions from specific classes of combustion appliances are less well characterised. The major gaps in knowledge concern; (i) characterisation of the atmospheric transformations of wood smoke particles, (ii) characterisation of the physicochemical properties of wood smoke particles in ambient and indoor environments, and (iii) identification of the physicochemical properties that influence the biological effects of wood smoke particles.

  • 5.
    Boman, Christoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Characterization of inorganic particulate matter from residential combustion of pelletized biomass fuels2004In: Energy and Fuels, ISSN 0887-0624, Vol. 18, no 2, p. 338-348Article in journal (Refereed)
    Abstract [en]

    The increased focus on potential adverse health effects associated with exposure to ambient particulate matter (PM) motivates a careful characterization of particle emissions from different sources. Combustion is a major anthropogenic source of fine PM, and, in urban areas, traditional residential wood combustion can be a major contributor. New and upgraded biomass fuels have become more common, and fuel pellets are especially well-suited for the residential market. The objective of the present work was to determine the mass size distributions, elemental distributions, and inorganic-phase distributions of PM from different residential combustion appliances and pelletized biomass fuels. In addition, chemical equilibrium model calculations of the combustion process were used to interpret the experimental findings. Six different typical pellet fuels were combusted in three different commercial pellet burners (10−15 kW). The experiments were performed in a newly designed experimental setup that enables constant-volume sampling. Total-PM mass concentrations were measured using conventional filters, and the fractions of products of incomplete combustion and inorganic material were thermally determined. Particle mass size distributions were determined using a 13-step low-pressure cascade impactor with a precyclone. The PM was analyzed for morphology (using environmental scanning electron microscopy, ESEM), elemental composition (using energy-dispersive spectroscopy, EDS), and crystalline phases (using X-ray diffractometry, XRD). For complementary chemical structural characterization, time-of-flight secondary ion mass spectrometry (TOF−SIMS), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy were also used. The emitted particles were mainly found in the fine (<1 μm) mode with mass median aerodynamic diameters of 0.20−0.39 μm and an average PM1 of 89.5% ± 7.4% of total PM. Minor coarse-mode fractions (>1 μm) were present primarily in the experiments with bark and logging residues. Relatively large and varying amounts (28%−92%) were determined to be products of incomplete combustion. The inorganic elemental compositions of the fine particles were dominated by potassium, chlorine, and sulfur, with minor amounts of sodium and zinc. The dominating alkali phase was KCl, with minor but varying amounts of K3Na(SO4)2 and, in some cases, also K2SO4. The results showed that zinc is almost fully volatilized, subsequently and presumably forming a more complex solid phase than that previously suggested (ZnO). However, the formation mechanism and exact phase identification remain to be elucidated. With some constrains, the results also showed that the amounts and speciation of the inorganic PM seemed to be quite similar to that predicted by chemical equilibrium calculations.

  • 6.
    Boman, Christoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Energy Technology Center, Piteå, Sweden.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Thanning, Lennart
    FOI.
    Effects of increased small-scale biomass pellet combustion on ambient air quality in residential areas: A parametric dispersion modeling study2003In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 24, no 6, p. 465-474Article in journal (Refereed)
    Abstract [en]

    Sweden's goals of contemporaneously reducing CO2 emissions and phasing out nuclear power will require a maximum utilization of biomass fuels. This would imply a significant shift from electricity and fuel oil to biomass generated heat, but must also be accomplished without a deterioration of the local air quality. The most suitable energy carrier seems to be pelletized biomass fuels with their associated low emissions and considerable residential conversion potential. Using an underlying statistical design, a parametric dispersion modeling study was performed to estimate and illustrate the combined effects of source-specific, meteorological and modeling variables on the ambient air quality in a typical residential area for different conversion scenarios. The work nicely illustrated the benefits of combining statistical designs with model calculations. It further showed that the concentration of combustion related ambient THC was strongly related to conditions affecting the source strength, but only weakly to the dispersion conditions and model variables. Time of year (summer or winter); specific emission performance; extent of conversion from electricity; conversion from wood log combustion; and specific efficiency of the pellet appliances showed significant effects in descending order. The effects of local settings and model variables were relatively small, making the results more generally applicable. To accomplish the desired conversion to renewable energy in an ecologically and sustainable way, the emissions would have to be reduced to a maximum advisable limit of (given as CH4). Further, the results showed the potential positive influence by conversion from wood log to low emission pellet combustion.

  • 7.
    Boman, Christoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Westerholm, Roger
    Pettersson, Esbjörn
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Evaluation of a constant volume sampling set-up for residential biomass fired appliances: influence of dilution conditions on particulate and PAH emissions2005In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 29, no 4, p. 258-268Article in journal (Refereed)
    Abstract [en]

    Increased concerns about particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) emissions from residentialbiomass combustion and their potential health effects, motivates detailed emission measurements under controlled conditions. Traditional sampling in raw flue gases can suffer from drawbacks mainly related to transient flows and the condensable nature of organic compounds. Whole flow dilution with constantvolumesampling (CVS) is an alternative method but different samplingconditions may, however, influence the emission characteristics. The objective was to design a CVS system for emission measurements in residentialbiomassfiredappliances and determine the influence of dilutionsamplingconditions on the characteristics and distributions of PM and PAH. Softwood pellets were combusted in a pellet stove with variations in; dilution ratio (3–7x), sampling temperature (45–75 °C), dilution tunnel residence time (2–4 s) and fuel load (2.3 and 4.8 kW) according to a statistical experimental design. The samplingconditions did not influence either the emission concentrations of PM, CO and NO or the particle size distribution. Variations in residence time had no significant effect on any studied emission parameter. However, increased concentrations of organic gaseous carbon (OGC) and PAH were observed with increased dilution ratio. The distribution between particulate and semivolatile phase was influenced for 12 of the 37 analyzed PAH compounds, mainly by increased fractions of semivolatile material at higher sampling temperature. No influence of sampling temperature was observed for the concentrations of PAHtot or the dominating PAH compounds, i.e. phenanthrene, fluoranthene and pyrene. The results together with practical considerations also suggest sampling at 50±5 °C and 3–4 times dilution as robust and applicable conditions in the presently designed setup.

  • 8.
    Boman, Christoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pettersson, Esbjörn
    Energy Technology Centre, Piteå, Sweden.
    Westerholm, Roger
    Department of Analytical Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Stove performance and emission characteristics in residential wood log and pellet combustion: Part 1: Pellet stoves2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 1, p. 307-314Article in journal (Refereed)
    Abstract [en]

    Stove performance, characteristics, and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter, and chimney draft. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions, and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PMtot and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene, and benzene and the emissions of VOC varied in the range 1.1−42 mg/MJfuel. PAH emissions (2−340 μg/MJfuel) were generally dominated by phenanthrene, fluoranthene and pyrene. The PMtot values (15−45 mg/MJfuel) were in all cases dominated by fine particles with mass median diameters in the range 100−200 nm, peak mobility diameters of 50−85 nm, and number concentrations in the range 4 × 1013 to 3 × 1014 particles/MJfuel. During high load conditions, the particulate matter was totally dominated by inorganic particles at 15−25 mg/MJfuel consisting of potassium, sodium, sulfur, and chlorine, in the form of K2SO4, K3Na(SO4)2, and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data.

  • 9.
    Boman, Christoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash transformation chemistry in biomass fixed beds with focus on slagging and aerosols: 20 years of research and new developments2017In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal (Other academic)
  • 10.
    Boman, Christoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Trace element enrichment and behavior in wood pellet production and combustion processes.Manuscript (Other academic)
  • 11.
    Borén, Eleonora
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft Institute for Water Education, Delft, The Netherlands.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Carlborg, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kaolin as fuel additive in grate combustion of biomass to mitigate ash related problems and particle emissions2022In: Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment / [ed] Markus Broström, Department of Applied Physics and Electronics, Umeå University , 2022Conference paper (Refereed)
    Abstract [en]

    Bioenergy is a fundamental part in sustainable development but use of novel fuel feedstocks potentiallymore sustainable may also bring associated ash-related challenges in practical operation that could bemitigated by co-conversion or additives. Kaolin, a clay mineral, is an additive known to be beneficialfor reduction of slagging tendencies and particulate matter formation in combustion of traditionalwoody-type biomass but its impact on thermal conversion of other biomasses still warrantsinvestigation. The aim of the present work is therefore to investigate how thermal conversion of atypical K-Ca-rich woody-type biomass, poplar, and a K-Si-rich annual crop, grass, is affected by kaolinaddition in fixed bed combustion. Additivation levels were calculated according to amount of alkaliintroduced with the two feedstocks, and incorporated by co-pelletization, in the case of poplar, anadditional blending d method was tested, by powder coating of pellets The results show that kaolinaddition improved the bottom ash characteristics, especially for grass, but the main differencesbetween feedstocks were found in particulate matter and flue gas composition. The particulate matterconcentrations were reduced with kaolin addition due to removal of gaseous K compounds which inturn caused higher SOx and HCl concentrations due to the lower amount of gaseous alkali for reaction.Further, initially high CO levels observed for both fuel feedstocks were reduced with the addition ofkaolin where co-pelletization with poplar proved more effective than powder coating the fuel particlesurfaces. This suggests that high concentrations of gaseous K-compounds may impact conversion ofthe carbonaceous matrix negatively.

  • 12.
    Boström, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Ash transformation chemistry during energy conversion of biomass2010In: Impacts of Fuel Quality on Power Production & Environment: 29/08/2010 - 03/09/2010, Impacts of Fuel Quality , 2010Conference paper (Refereed)
    Abstract [en]

    There is relatively extensive knowledge available concerning ash transformation reactions during energy conversion of woody biomass. Traditionally, these assortments have constituted the main resources for heating in Sweden. In recent decades the utilization of these energy carriers has increased, from a low technology residential small scale level to industrial scale (e.g. CHP plants). Along this evolution ash-chemical related phenomena for woody biomass has been observed and studied. So, presently the understanding for these are, if not complete, fairly good. Briefly, from a chemical point of view the ash from woody biomass could be characterized as a silicate dominated systems with varying content of basic oxides and with relatively high degree of volatilization of alkali sulfates and chlorides. Thus, the main ash transformation mechanisms in these systems have been outlined. Here, an attempt to give a general description of the ash transformation reactions of biomass fuels is presented, with the intention to provide guidance in the understanding of ash matter behavior in the utilization of any biomass fuel, primarily from knowledge of the concentrations of ash forming elements but also by considering the physical condition in the specific combustion appliance and the physical characteristic of the biomass fuel. Furthermore, since the demand for CO2-neutral energy resources has increased the last years and will continue to do so in the foreseeable future, other biomasses as for instance agricultural crops has become highly interesting. Globally, the availability of these shows large variation. In Sweden, for instance, which is a relatively spare populated country with large forests, these bio-masses will play a secondary role, although not insignificant. In other parts of the world, more densely populated and with a large agricultural sector, such bio-masses may constitute the main energy bio-mass resource in the future. However, the content of ash forming matter in agricultural bio-mass is rather different in comparison to woody biomass. Firstly, the content is much higher; from being about 0.3 – 0.5% (wt) in stem wood, it can amount to between 2 and 10 %(wt) in agricultural biomass. In addition, the composition of the ash forming matter is different. Shortly, the main difference is due to a much higher content of phosphorus (occasionally also silicon) which has major consequences on the ash-transformation reactions. In many crops, the concentration of phosphorus and silicon is equivalent, which (depending on the concentration levels of basic oxides) may result in a phosphate dominated ash. The properties of this ash are in several aspects different from the silicate dominated woody biomass ash and will consequently behave differently in various types of energy conversion systems. The knowledge about phosphate dominated ash systems has so far been scarce. We have been working with these systems, both with basic and applied research, for about a decade know. Some general experiences and conclusions as well as some specific examples of our research will be presented.

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  • 13.
    Boström, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Eriksson, Gunnar
    Division of Energy Engineering, Department of Applied Physics and Mechanical Engineering, Luleå Technical University.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Division of Energy Engineering, Department of Applied Physics and Mechanical Engineering, Luleå Technical University.
    Ash transformations in fluidized-bed combustion of rapeseed meal2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, no 5, p. 2700-2706Article in journal (Refereed)
    Abstract [en]

    The global production of rapeoil is increasing. A byproduct is rapeseed meal that is a result of the oil extraction process. Presently the rapeseed meal mainly is utilized as animal feed. An interesting alternative use is, however, energy conversion by combustion. This study was undertaken to determine the combustion properties of rapeseed meal and bark mixtures in a bubbling fluidized bed, with emphasis on gas emissions, ash formation, -fractionation and -interaction with the bed material. Due to the high content of phosphorus in rapeseed meal the fuel ash is dominated by phosphates, in contrast to most woody biomass where the ash is dominated by silicates. From a fluidized bed combustion (FBC) point of view, rapeseed meal could be a suitable fuel. Considering FBC agglomeration effects, pure rapeseed meal is in level with the most suitable fuels, as earlier tested by the methods utilized in the present investigation. The SO2 emission, however, is higher than most woody biomass fuels as a direct consequence of the high levels of sulfur in the fuel. Also the particulate matter emission, both submicron and coarser particles, is higher. Again this can be attributed the high ash content of rapeseed meal. The high abundance of SO2 is apparently effective for sulfatization of KCl in the flue gas. Practically no KCl was observed in the particulate matter of the flue gas. A striking difference in the mechanisms of bed agglomeration for rapeseed meal compared to woody biomass fuels was also observed. The ubiquitous continuous layers on the bed grains found in FBC combustion of woody biomass fuels was not observed in the present investigation. Instead very thin and discontinuous layers were observed together with isolated partly melted bed ash particles. The latter could occasionally be seen as adhered to the quartz bed grains. Apparently the bed agglomeration mechanism, that obviously demanded rather high temperatures, involved more of adhesion by partly melted ash derived potassium -calcium phosphate bed ash particles/droplets than direct attack of gaseous alkali on the quartz bed grains forming potassium -calcium silicate rich bed grain layers. Am explanation could be found in the considerable higher affinity for base cations of phosphorus than silicon. This will to a great extent withdraw the present basic oxides from attacking the quartz bed grains with agglomeration at low temperatures as a result.

  • 14.
    Boström, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Grimm, Alejandro
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Björnbom, Emilia
    Chemical Engineering and Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Öhman, Marcus
    Division of Energy Engineering, Luleå University of Technology, SE- 971 87 Luleå, Sweden.
    Influence of kaolin and calcite additives on ash transformations in small-scale combustion of oat2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, no 10, p. 5184-5190Article in journal (Refereed)
    Abstract [en]

    A growing interest has been observed for the use of cereal grains in small- and medium-scale heating. Previous studies have been performed to determine the fuel quality of various cereal grains for combustion purposes. The present investigation was undertaken in order to elucidate the potential abatement of low-temperature corrosion and deposits formation by using fuel additives (calcite and kaolin) during combustion of oat. Special emphasis was put on understanding the role of slag and bottom ash composition on the volatilization of species responsible for fouling and emission of fine particles and acid gases. The ash fractions were analyzed with scanning electron micro scopy/energy dispersive spectroscopy (SEM/EDS), for elemental composition, and with X-ray diffraction (XRD) for identification of crystalline phases. The previously reported K and Si capturing effects of kaolin additive were observed also in the present study using P-rich biomass fuels. That is, the prerequisites for the formation of low melting K-rich silicates were reduced. The result of using kaolin additive on the bottom ash was that no slag was formed. The effect of the kaolin additive on the formation of submicrometer flue gas particles was an increased share of condensed K-phosphates at the expense of K-sulfate and KCl. The latter phase was almost completely absent in the particulate matter. Consequently, the levels of HCl and SO2 in the flue gases increased somewhat. The addition of both calcite assortments increased the amount of farmed slag, although to a considerably higher extent for the precipitated calcite. P was captured to a higher degree in the bottom ash, compared to the combustion of pure oat. The effect of the calcite additives on the fine particle emissions in the flue gases was that the share of K-phosphate decreased considerably, while the content of K-sulfate and KCl increased. Consequently, also the flue-gas levels of acidic HCl and SO2 decreased. This implies that the low-temperature corrosion observed in small-scale combustion of oat possibly can be abated by employing calcite additives. Alternatively, if problems with slagging and deposition of corrosive matter at heat convection surfaces are to be avoided, kaolin additive can be utilized, on the condition that the higher concentrations of acidic gases can be tolerated.

  • 15.
    Boström, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash transformation chemistry during combustion of biomass, theory and technical applications2017In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal (Other academic)
  • 16.
    Boström, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Grimm, Alejandro
    Luleå Univ Technol, Div Energy Sci, SE-97187 Luleå, Sweden.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå Univ Technol, Div Energy Sci, SE-97187 Luleå, Sweden.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash Transformation Chemistry during Combustion of Biomass2012In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 1, p. 85-93Article in journal (Refereed)
    Abstract [en]

    There is relatively extensive knowledge available concerning ash transformation reactions during combustion of woody biomass. In recent decades, the use of these energy carriers has increased, from a low-technology residential small-scale level to an industrial scale. Along this evolution, ash chemical-related phenomena for woody biomass have been observed and studied. Therefore, presently the understanding for these are, if not complete, fairly good. However, because the demand for CO2-neutral energy resources has increased recently and will continue to increase in the foreseeable future, other biomasses, such as, for instance, agricultural crops, have become highly interesting. The ash-forming matter in agricultural biomass is rather different in comparison to woody biomass, with a higher content of phosphorus as a distinctive feature. The knowledge about the ash transformation behavior in these systems is far from complete. Here, an attempt to give a schematic but general description of the ash transformation reactions of biomass fuels is presented in terms of a conceptual model, with the intention to provide guidance in the understanding of ash matter behavior in the use of any biomass fuel, primarily from the knowledge of the concentrations of ash-forming elements. The model was organized in primary and secondary reactions. Restrictions on the theoretical model in terms of reactivity limitations and physical conditions of the conversion process were discussed and exemplified, and some principal differences between biomass ashes dominated by Si and P, separately, were outlined and discussed.

  • 17.
    Carvalho, Ricardo L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Centre for Environmental and Marine Studies, Dept. of Environment and Planning, University of Aveiro, Aveiro, Portugal; Laboratory of Renewable Energy and Environmental Comfort, Institute of Education, Science and Technology of Ceará, Fortaleza, Brazil.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lopez, N.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyambane, Anne
    Nyberg, Gert
    Diaz-Chavez, Rocio
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Household air pollution mitigation with integrated biomass/cookstove strategies in Western Kenya2019In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 131, p. 168-186Article in journal (Refereed)
    Abstract [en]

    Traditional cooking is today's largest global environmental health risk. Over 640 million people in Africa are expected to rely on biomass for cooking by 2040. In Kenya, cooking inefficiently with wood and charcoal persists as a cause of deforestation and household air pollution. This research analyses the effects of four biomass cookstove strategies on reducing air pollutant emissions in Kisumu County between 2015 and 2035 using the Long-Range Energy Alternatives Planning system. The Business as Usual scenario (BAU) was developed considering the historical trends in household energy use. Energy transition scenarios to Improved Cookstoves (ICS), Pellet Gasifier Stoves (PGS) and Biogas Stoves (BGS) were applied to examine the impact of these systems on energy savings and air pollution mitigation. An integrated scenario (INT) was evaluated as a mix of the ICS, PGS and BGS. The highest energy savings, in relation to the BAU, are achieved in the BGS (30.9%), followed by the INT (23.5%), PGS (19.4%) and ICS (9.2%). The BGS offers the highest reduction in the GHG (37.6%), CH4 (94.3%), NMVOCs (85.0%), CO (97.4%), PM2.5 (64.7%) and BC (48.4%) emissions, and the PGS the highest reduction in the N2O (83.0%) and NOx (90.7%) emissions, in relation to the BAU.

  • 18.
    Carvalho, Ricardo L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Centre of Environment and Marine Studies, University of Aveiro, Aveiro, Portugal.
    Yadav, Pooja
    Dept. of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    García-López, Naxto
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyberg, Gert
    Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Diaz-Chavez, Rocio
    Stockholm Environment Institute, Africa Centre, c/o World Agroforestry Centre, P.O. Box 30677, Nairobi, Kenya.
    Upadhyayula, Venkata Krishna Kumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Athanassiadis, Dimitris
    Dept. of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Bioenergy strategies to address deforestation and household air pollution in western Kenya2019In: European Biomass Conference and Exhibition Proceedings, ETA-Florence Renewable Energies , 2019, p. 1536-1542Conference paper (Refereed)
    Abstract [en]

    Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden disease due to household air pollution. The Long-Range Energy Alternatives Planning (LEAP) system and the Life-Cycle Assessment tool Simapro 8.5 were applied for analyzing biomass strategies for the region. The calculation of the residential energy consumption and emissions was based on scientific reviews and original data from experimental studies. The research shows the effect of four biomass strategies on the reduction of wood fuel use and short-lived climate pollutant emissions. A Business As Usual scenario (BAU) considered the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) considered the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluated a mix of the ICS, PGS and BGS. The study shows that, energy use will increase by 8% (BGS), 20% (INT), 26% (PGS), 42% (ICS) and 56% (BAU). The BGS has the lowest impact on global warming, particle formation, terrestrial acidification, fossil resource scarcity, water consumption, as well as on eutrophication followed by the PGS and INT.

  • 19.
    Carvalho, Ricardo Luís
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Centre for Environmental and Marine Studies, Department of Environment and Planning, University of Aveiro, Aveiro, Portugal.
    Yadav, Pooja
    García-López, Naxto
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyberg, Gert
    Diaz-Chavez, Rocio
    Upadhyayula, Venkata Krishna Kumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Athanassiadis, Dimitris
    Environmental Sustainability of Bioenergy Strategies in Western Kenya to Address Household Air Pollution2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 3, article id 719Article in journal (Refereed)
    Abstract [en]

    Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden of disease due to household air pollution. Efficient biomass cooking is a local-based renewable energy solution to address this issue. The Life-Cycle Assessment tool Simapro 8.5 is applied for analyzing the environmental impact of four biomass cooking strategies for the Kisumu County, with analysis based on a previous energy modelling study, and literature and background data from the Ecoinvent and Agrifootprint databases applied to the region. A Business-As-Usual scenario (BAU) considers the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) consider the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluates a mix of the ICS, PGS and BGS. In the BGS, the available biomass waste is sufficient to be upcycled and fulfill cooking demands by 2035. This scenario has the lowest impact on all impact categories analyzed followed by the PGS and INT. Further work should address a detailed socio-economic analysis of the analyzed scenarios.

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  • 20.
    Diaz-Ramirez, Maryori
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sebastian, Fernando
    Royo, Javier
    Xiong, Shaojun
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash Characterization and Transformation Behavior of the Fixed-Bed Combustion of Novel Crops: Poplar, Brassica, and Cassava Fuels2012In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 6, p. 3218-3229Article in journal (Refereed)
    Abstract [en]

    New biofuel raw materials for energy pellet production are now being studied as potential energy sources for the heating market. Because of the complexity of the chemical and physical properties of novel fuels, such as some agricultural residues and energy crops, the study of their ash-related aspects is crucial for the sustainable development of this potential energy sector. Ash fractions formed during fixed-bed combustion of different pelletized novel crops; i.e., two Mediterranean crops (one herbaceous, brassica, and one woody species, poplar) and three Chinese cassava stems (cassava species from three different Chinese regions), and three Chinese cassava stems (cassava species from three different Chinese regions), were characterized, and their formation paths assessed in this study. Special emphasis was placed on elucidating the role of major ash-forming elements in the fractionation and transformation behavior, leading to the formation of bottom ash, deposits, and particulate emissions (fine and coarse ash particle fractions) on the basis of experimental data. In the Mediterranean fuels, the predominant ash fraction obtained was bottom ash, mainly characterized by silicates. Phosphates were found to be the main crystalline phases in the Chinese fuels. The slagging tendency was low for all of the fuels, although more significant for the cassava species under the studied conditions. Further, combustion of the studied Chinese energy crops resulted in a considerably finer particle fraction compared to the Mediterranean fuels. Deposits and particulate matter were dominated by K-sulfates as well as K-chloride in all fuels (except poplar), with the occurrence of K-phosphates for cassava pellets. Overall, this study showed fundamental differences in ash transformation behavior during combustion of P-rich fuels (i.e., cassava mixtures) compared to Si-rich fuels (i.e., poplar and brassica mixtures). Of major importance is the experimental verification of the higher thermodynamic stability of phosphates in relation to silicates. Furthermore, in P-rich fuels at high (K + Na)/(Ca + Mg) ratios, a significant degree of alkali metal volatilization occurs, which forms larger amounts of particulate matter, whereas this ratio has no/low effect in Si-rich fuels at high alkali metal ratios.

  • 21.
    Díaz-Ramírez, Maryori
    et al.
    Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain; Centre of Research for Energy Resources and Consumption, CIRCE Foundation, Zaragoza, Spain.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sebastián, Fernando
    Centre of Research for Energy Resources and Consumption, CIRCE Foundation, Zaragoza, Spain.
    Royo, Javier
    Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain.
    Xiong, Shaojun
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Environmental performance of three novel opportunity biofuels: poplar, brassica and cassava during fixed bed combustion2013In: Herbaceous plants: cultivation methods, grazing and environmental impacts / [ed] Florian Wallner, Nova Science Publishers, Inc., 2013, p. 133-147Chapter in book (Refereed)
    Abstract [en]

    In the last few decades several types of solid biofuels have been proposed as possible sources for heat generation because of growing concerns about environmental pollution, and future fossil fuel supply uncertainties. Among other biomass assortments, short rotation coppice and herbaceous species have been considered. An important aspect to be evaluated to enable a sustainable introduction of such novel fuels is related to their environmental performance during combustion. In this work, three fuel types; one herbaceous energy crop and one short rotation coppice (both cultivated and pelletized in Spain), together with one agricultural residue (cultivated in China) have been assessed in terms of their emission levels of gases (CO and NOX) and particulate matter. The experiments showed that combustion of the fuels was attained under an acceptable level of CO emissions. However, concentration of NOX was rather high, but perhaps more important, a considerably high formation of fine particle emissions was observed. Consequently, the incorporation of primary or secondary particle precipitating reduction measures might be needed. In addition, the high ash content in these fuels can severely deteriorate the combustion performance and reliability. Thus, specially designed burners/grate units are therefore needed if a utilization of these fuels in small and medium scale combustion systems seeks to be feasible. Although the applicability of introducing this kind of biofuels to the residential heating sector perhaps seems to be rather limited, it should not always be rejected. Nevertheless, technology improvements would have to be considered to manage the current limitations. 

  • 22.
    Enestam, Sonja
    et al.
    Åbo Akademi.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Niemi, Jere
    Metso Power.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Mäkele, Kari
    Metso Power.
    Hupa, Mikko
    Åbo Akademi.
    Occurrence of zinc and lead in aerosols and deposits in the fluidized bed combustion of recovered waste wood:  Part 1: Samples from boilers2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 4, p. 1396-1404Article in journal (Refereed)
    Abstract [en]

    Combustion of recovered waste wood (RWW) has led to increased fouling and corrosion of furnace walls, superheaters, and economizers. These problems have been associated mainly with chlorine, zinc, and lead in the deposits but also with sodium and titanium. The presence of lead and zinc compounds, especially lead and zinc chlorides, has been shown to increase the corrosivity of the deposits even at relatively low metal temperatures (230−450 °C). The present work determined experimentally the distribution and speciation of zinc and lead compounds in aerosol particles and deposits in the fluidized-bed combustion of RWW. Measurements were conducted in both a full-scale (20 MWth) plant with as-received RWW and in a pilot-scale (2 MWth) setup with as-received RWW and RWW doped with zinc and lead. The results show that the amount and speciation of zinc and lead in the deposits vary depending upon the fuel composition, flue gas temperature, and metal temperature. Both lead and zinc chlorides are found in temperature ranges typical for the primary superheater area. A caracolite-type compound [Na3Pb2(SO4)3Cl] was identified in deposits from the economizer area and K2ZnCl4 in the sub-micrometer aerosol particle fraction.

  • 23. Eriksson, A. C.
    et al.
    Nordin, E. Z.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pettersson, E.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Swietlicki, E.
    Bergvall, C.
    Westerholm, R.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pagels, J. H.
    Particulate PAH Emissions from Residential Biomass Combustion: Time-Resolved Analysis with Aerosol Mass Spectrometry2014In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 12, p. 7143-7150Article in journal (Refereed)
    Abstract [en]

    Time-resolved emissions of particulate polycyclic aromatic hydrocarbons (PAHs) and total organic particulate matter (OA) from a wood log stove and an adjusted pellet stove were investigated with high-resolution time-of-flight aerosol mass spectrometry (ANIS). The highest OA emissions were found during the addition of log wood on glowing embers, that is, slow burning pyrolysis conditions. These emissions contained about 1% PAHs (of OA). The highest PAH emissions were found during fast burning under hot air starved combustion conditions, in both stoves. In the latter case, PAHs contributed up to 40% of OA, likely due to thermal degradation of other condensable species. The distribution of PAHs was also shifted toward larger molecules in these emissions. ANIS signals attributed to PAHs were found at molecular weights up to 600 Da. The vacuum aerodynamic size distribution was found to be bimodal with a smaller mode (D-va similar to 200 nm) dominating under hot air starved combustion and a larger sized mode dominating under slow burning pyrolysis (D-va similar to 600 nm). Simultaneous reduction of PAHs, OA and total particulate matter from residential biomass combustion may prove to be a challenge for environmental legislation efforts as these classes of emissions are elevated at different combustion conditions.

  • 24.
    Eriksson, Gunnar
    et al.
    Forest Resource Management, Swedish University of Agricultural Science, Umeå, Sweden.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Bergsten, Urban
    Forest Ecology and Management, Swedish University of Agricultural Science, Umeå, Sweden.
    Bergström, Dan
    Forest Planning and Operations Management, Forest Resource Management, Swedish University of Agricultural Science, Umeå, Sweden.
    Fuel characterization of pellet chips2011In: Forest products journal, ISSN 0015-7473, Vol. 61, no 2, p. 143-148Article in journal (Refereed)
    Abstract [en]

    Small hardwood chips, known as pellet chips, were characterized and combusted in two different pellet burners, installed in a residential boiler specially designed for pellet combustion. The average particle mass was about 10 percent of the mass of an 8-mm pellet, with a similar surface-to-volume ratio. The bulk density of pellet chips was 160 to 170 kg m<sup>-3</sup> at 10 percent moisture content (about 25% to 35% of 8-mm pellet bulk densities). The combustion performance was good, with average O<sub>2</sub> and CO values (by volume) at 17.6 percent (SD, 0.6%) and 200 ppm (SD, 210 ppm), respectively, for the bottom-fed burner and 14.2 percent (SD, 1.1%) and 330 ppm (SD, 93 ppm), respectively, for the top-fed burner. Thus the study indicates that pellet chips produced with commercially available equipment can be used in ordinary pellet combustors, provided that the fuel feeding rates are increased and the moisture content well below 20 percent. More accurate market assessments will require the investigation of the performance of different types of combustion equipment with fuels of different qualities.

  • 25. Erlandsson, Lena
    et al.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nääv, Åsa
    Krais, Annette M.
    Strandberg, Bo
    Lundh, Thomas
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Isaxon, Christina
    Hansson, Stefan R.
    Malmqvist, Ebba
    Exposure to wood smoke particles leads to inflammation, disrupted proliferation and damage to cellular structures in a human first trimester trophoblast cell line2020In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 264, article id 114790Article in journal (Refereed)
    Abstract [en]

    The ongoing transition to renewable fuel sources has led to increased use of wood and other biomass fuels. The physiochemical characteristics of biomass combustion derived aerosols depends on appliances, fuel and operation procedures, and particles generated during incomplete combustion are linked to toxicity. Frequent indoor wood burning is related to severe health problems such as negative effects on airways and inflammation, as well as chronic hypoxia and pathological changes in placentas, adverse pregnancy outcome, preterm delivery and increased risk of preeclampsia. The presence of combustion-derived black carbon particles at both the maternal and fetal side of placentas suggests that particles can reach the fetus. Air pollution particles have also been shown to inhibit trophoblast migration and invasion, which are vital functions for the development of the placenta during the first trimester. In this study we exposed a placental first trimester trophoblast cell line to wood smoke particles emitted under Nominal Burn rate (NB) or High Burn rate (HB). The particles were visible inside exposed cells and localized to the mitochondria, causing ultrastructural changes in mitochondria and endoplasmic reticulum. Exposed cells showed decreased secretion of the pregnancy marker human chorionic gonadotropin, increased secretion of IL-6, disrupted membrane integrity, disrupted proliferation and contained specific polycyclic aromatic hydrocarbons (PAHs) from the particles. Taken together, these results suggest that wood smoke particles can enter trophoblasts and have detrimental effects early in pregnancy by disrupting critical trophoblast functions needed for normal placenta development and function. This could contribute to the underlying mechanisms leading to pregnancy complications such as miscarriage, premature birth, preeclampsia and/or fetal growth restriction. This study support the general recommendation that more efficient combustion technologies and burning practices should be adopted to reduce some of the toxicity generated during wood burning. 

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  • 26.
    Fagerström, Jonathan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Dan, Boström
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Fuel conversion of large samples in a thermogravimetric analyzer set-up: method description and applications2011Conference paper (Refereed)
  • 27.
    Fagerström, Jonathan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Näzelius, Ida-Linn
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Gilbe, Carl
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Influence of Peat Ash Composition on Particle Emissions and Slag Formation in Biomass Grate Co-combustion2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 5, p. 3403-3411Article in journal (Refereed)
    Abstract [en]

    Co-combustion by fuel blending of peat and biomass has shown positive effects on operational problems. However, peat ash compositions vary considerably, and this has been shown to affect the potential for operational problems in different fuel-blending situations. The present work used three different peat types with the objective to elucidate how the variation in peat ash composition influences both particle emissions and slag formation during co-combustion with three different biomasses in a small-scale pellet boiler. Estimations of potassium release and slag formation were performed and discussed in relation to fuel composition in the (K2O + Na2O) (CaO + MgO) (SiO2) system. All tested peat types reduced the fine particle emissions by capturing potassium into the bottom ash as one or several of the following forms: slag, sulfates, chlorides, and alumina silicates. However, there were considerable differences between the peat types, presumably depending upon both their content and mineral composition of silicon, calcium, aluminum, and sulfur. Some general important and beneficial properties of peat type in co-combustion situations with biomass are defined here, but the specific blending proportion of peat should be decided on an individual basis for each scenario based on the relative contents in the fuel mixture of the most relevant ash-forming elements.

  • 28.
    Fagerström, Jonathan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Steinvall, Erik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Alkali transformation during single pellet combustion of soft wood and wheat straw2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 143, p. 204-212Article in journal (Refereed)
    Abstract [en]

    Controlling slag and deposit formation during thermochemical fuel conversion requires a fundamental understanding about ash transformation. In this work, a macro-TGA reactor was used to determine the release of ash forming elements during devolatilization and char combustion of single pellets. Soft wood and wheat straw were combusted at two temperatures (700 °C and 1000 °C) and the residual ashes were collected and analyzed for morphology, elemental and phase composition. The results showed that the single pellet combustion exhibit similar release character as in grate boilers. The temporal release was found to be both temperature and fuel dependent. For wood, the release of potassium occurred mostly during char combustion regardless of furnace temperature. Similar results were found for straw at 700 °C, but the temperature increase to 1000 °C implied that the release occurred already during devolatilization. The differences are presumably explained by different fuel phase compositions. The residual ash were composed of three different categories of phases; crystalline compounds, molten ash (glass) and char, and the work concludes that K was captured by crystalline K/Ca-carbonates as well as in amorphous glassy silicates for wood, and by almost fully molten ash of glassy silicates for straw. The fuel conversion processes occurring on a grate influence the fuel combustibility in terms of e.g. burnout, slag formation and release of fine particle and deposit forming matter, and the present work has given novel insights into the specific alkali behavior during biomass fuel conversion.

  • 29.
    Grimm, Alejandro
    et al.
    Lulea Univ Technol, Dept Engn Sci & Math, SE-97187 Lulea, Sweden.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Lulea Univ Technol, Dept Engn Sci & Math, SE-97187 Lulea, Sweden.
    Influence of phosphorus on alkali distribution during combustion of logging residues and wheat straw in a bench-scale fluidized bed2012In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 5, p. 3012-3023Article in journal (Refereed)
    Abstract [en]

    The influence of phosphorus on the alkali distribution in fluidized (quartz) bed combustion using two different typical biomasses (logging residues and wheat straw) was studied. Phosphoric acid (H3PO4) was used as an additive. The produced ash fractions were analyzed for morphology and elemental composition by scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), and crystalline phases by powder X-ray diffraction (P-XRD). For both fuel assortments tested, a reduction of volatilized deposit and fine particle-forming matter, containing mainly KCl, was achieved by adding phosphorus. For the wheat straw, this effect was considerable at medium and high phosphorus addition. As a consequence, an increased amount of potassium was found in the coarse ash particle fractions, principally as CaKPO4, KMgPO4, and CaK2P2O7, at the same time that the levels of HCl and SO2 in the flue gases increased. Generally, the addition of phosphorus to the studied biomasses changed the alkali distribution from being dominated by amorphous K-silicate coarse ash fractions and fine particulate KCl, to a system dominated by crystalline coarse ash of K-Ca/Mg-phosphates and fine particulate K2SO4. This implies that the fouling and high-temperature corrosion observed in industrial-scale combustion of problematic biofuels can possibly be reduced by employing additives rich in reactive phosphorus, on the condition that the higher concentrations of acidic gases can be tolerated. In order to achieve these effects, the relationship between alkali and alkaline-earth metals (i.e., (K + Na)/(Ca + Mg)) in the overall fuel ash must be considered. With respect to this, the formation of low-temperature-melting alkali-rich phosphates should not be promoted, to avoid potential increases in bed agglomeration tendencies and phosphorus release from the bed.

  • 30.
    Grimm, Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Diaz, Maryori
    Eriksson, Gunnar
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Effects of phosphorus addition by additives or co-firing on the ash transformation processes such as bed agglomerations and deposit formation during combustion of ash-rich biomass fuels2009In: 17th European Biomass Conference & Exhibition - Proceedings: From Research to Industry and Markets, 2009Conference paper (Refereed)
  • 31.
    Grimm, Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Eriksson, Gunnar
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Effekter av fosfortillsats vid förbränning av biomassa2010Report (Other academic)
    Abstract [sv]

    Resultaten från försöken visar att fosforrika additiv kan vara intressanta för att reducera beläggningsbildning och högtemperaturkorrosion utan att i någon större omfattning öka slaggnings- och bäddagglomereringstendensen hos typiska biobränslen. För att erhålla en märkbar positiv effekt av kaliumbindning till fosfater krävs att mängden kalcium och magnesium i den slutgiltiga bränslemixen inte är alltför hög relativt mängden fosfor, då framför allt Ca men till viss del även Mg reagerar med P innan K binds in effektivt. Generellt behövs troligen inblandningsgrader motsvarande en molkvot P/(K+Na+2/3Mg+2/3Ca) i bränslemixen som närmar sig 1. För att erhålla en molkvot på 1 i ett typiskt halm-, salix- eller grotbränsle innebär det i praktiken en fosfortillsats motsvarande 12, 4.7 respektive 3.7 gram rent P per kg torrt bränsle.

  • 32.
    Hansson, Alva
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Rankin, Gregory
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Uski, O.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Sehlstedt, Maria
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    García-López, Naxto
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Behndig, Annelie F.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Muala, Ala
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Reduced bronchoalveolar macrophage phagocytosis and cytotoxic effects after controlled short-term exposure to wood smoke in healthy humans2023In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 20, no 1, article id 30Article in journal (Refereed)
    Abstract [en]

    Background: Exposure to wood smoke has been shown to contribute to adverse respiratory health effects including airway infections, but the underlying mechanisms are unclear. A preceding study failed to confirm any acute inflammation or cell influx in bronchial wash (BW) or bronchoalveolar lavage (BAL) 24 h after wood smoke exposure but showed unexpected reductions in leukocyte numbers. The present study was performed to investigate responses at an earlier phase, regarding potential development of acute inflammation, as well as indications of cytotoxicity.

    Methods: In a double-blind, randomised crossover study, 14 healthy participants were exposed for 2 h to filtered air and diluted wood smoke from incomplete wood log combustion in a common wood stove with a mean particulate matter concentration of 409 µg/m3. Bronchoscopy with BW and BAL was performed 6 h after exposure. Differential cell counts, assessment of DNA-damage and ex vivo analysis of phagocytic function of phagocytosing BAL cells were performed. Wood smoke particles were also collected for in vitro toxicological analyses using bronchial epithelial cells (BEAS-2B) and alveolar type II-like cells (A549).

    Results: Exposure to wood smoke increased BAL lactate dehydrogenase (LDH) (p = 0.04) and reduced the ex vivo alveolar macrophage phagocytic capacity (p = 0.03) and viability (p = 0.02) vs. filtered air. BAL eosinophil numbers were increased after wood smoke (p = 0.02), while other cell types were unaffected in BW and BAL. In vitro exposure to wood smoke particles confirmed increased DNA-damage, decreased metabolic activity and cell cycle disturbances.

    Conclusions: Exposure to wood smoke from incomplete combustion did not induce any acute airway inflammatory cell influx at 6 h, apart from eosinophils. However, there were indications of a cytotoxic reaction with increased LDH, reduced cell viability and impaired alveolar macrophage phagocytic capacity. These findings are in accordance with earlier bronchoscopy findings at 24 h and may provide evidence for the increased susceptibility to infections by biomass smoke exposure, reported in population-based studies.

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  • 33.
    Hansson, Alva
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Rankin, Gregory
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Uski, Oskari
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sehlstedt, Maria
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Bosson, Jenny A.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Lopez, Naxto Garcia
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Behndig, Annelie F.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Muala, Ala
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Wood smoke effects on epithelial cell lines and human airway cells2019In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 54Article in journal (Other academic)
  • 34.
    Hedayati, Ali
    et al.
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Falk, Joel
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Boren, Eleonora
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Ash Transformation during Fixed-Bed Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus2022In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 36, no 7, p. 3640-3653Article in journal (Refereed)
    Abstract [en]

    In this study, ash transformation during fixed-bed combustion of different agricultural opportunity fuels was investigated with a special focus on potassium (K) and phosphorus (P). The fuel pellets were combusted in an underfed fixed-bed pellet burner. Residual ashes (bottom ash and slag) and particulate matter were collected and characterized by scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography. The interpretation of the results was supported by thermodynamic equilibrium calculations. For all fuels, almost all P (>97%) was found in residual-/coarse ash fractions, while K showed different degrees of volatilization, depending on fuel composition. During combustion of poplar, which represents Ca-K-rich fuels, a carbonate melt rich in K and Ca decomposed into CaO, CO2, and gaseous K species at sufficiently high temperatures. Ca5(PO4)3OH was the main P-containing crystalline phase in the bottom ash. For wheat straw and grass, representing Si-K-rich fuels, a lower degree of K volatilization was observed than for poplar. P was found here in amorphous phosphosilicates and CaKPO4. For wheat grain residues, representing P-K-rich fuels, a high degree of both K and P retention was observed due to the interaction of K and P with the fuel-bed constituents, i.e., char, ash, and slag. The residual ash was almost completely melted and rich in P, K, and Mg. P was found in amorphous phosphates and different crystalline phases such as KMgPO4, K2CaP2O7, K2MgP2O7, and K4Mg4(P2O7)3. In general, the results therefore imply that an interaction between ash-forming elements in a single burning fuel particle and the surrounding bed ash or slag is important for the overall retention of P and K during fuel conversion in fixed-bed combustion of agricultural biomass fuels.

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  • 35.
    Hedayati, Ali
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Ash transformation during single-pellet combustion of agricultural biomass fuels – focus on K and P2018Conference paper (Other academic)
  • 36.
    Hedayati, Ali
    et al.
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kienzl, Norbert
    BEST - Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria.
    Öhman, Marcus
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Ash Transformation during Single-Pellet Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus2021In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 35, no 2, p. 1449-1464Article in journal (Refereed)
    Abstract [en]

    In this study, ash transformation and release of critical ash-forming elements during single-pellet combustion of different types of agricultural opportunity fuels were investigated. The work focused on potassium (K) and phosphorus (P). Single pellets of poplar, wheat straw, grass, and wheat grain residues were combusted in a macro-thermogravimetric analysis reactor at three different furnace temperatures (600, 800, and 950 °C). In order to study the transformation of inorganic matters at different stages of the thermal conversion process, the residues were collected before and after full devolatilization, as well as after complete char conversion. The residual char/ash was characterized by scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography, and the interpretation of results was supported by thermodynamic equilibrium calculations. During combustion of poplar, representing a Ca-K-rich woody energy crop, the main fraction of K remained in the residual ash primarily in the form of K2Ca(CO3)2 at lower temperatures and in a K-Ca-rich carbonate melt at higher temperatures. Almost all P retained in the ash and was mainly present in the form of hydroxyapatite. For the Si-K-rich agricultural biomass fuels with a minor (wheat straw) or moderate (grass) P content, the main fraction of K remained in the residual ash mostly in K-Ca-rich silicates. In general, almost all P was retained in the residual ash both in K-Ca-P-Si-rich amorphous structures, possibly in phosphosilicate-rich melts, and in crystalline forms as hydroxyapatite, CaKPO4, and calcium phosphate silicate. For the wheat grain, representing a K-P-rich fuel, the main fraction of K and P remained in the residual ash in the form of K-Mg-rich phosphates. The results showed that in general for all studied fuels, the main release of P occurred during the devolatilization stage, while the main release of K occurred during char combustion. Furthermore, less than 20% of P and 35% of K was released at the highest furnace temperature for all fuels.

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  • 37.
    Hedayati, Ali
    et al.
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Sefidari, Hamid
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden; RISE ETC (Energy Technology Centre) AB, Box 726, Piteå, Sweden.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kienzl, Norbert
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria.
    Öhman, Marcus
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Ash transformation during single-pellet gasification of agricultural biomass with focus on potassium and phosphorus2021In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 217, article id 106805Article in journal (Refereed)
    Abstract [en]

    Agricultural biomasses and residues can play an important role in the global bioenergy system but their potential is limited by the risk of several ash-related problems such as deposit formation, slagging, and particle emissions during their thermal conversion. Therefore, a thorough understanding of the ash transformation reactions is required for this type of fuels. The present work investigates ash transformation reactions and the release of critical ash-forming elements with a special focus on K and P during the single-pellet gasification of different types of agricultural biomass fuels, namely, poplar, grass, and wheat grain residues. Each fuel was gasified as a single pellet at three different temperatures (600, 800, and 950 °C) in a Macro-TGA reactor. The residues from different stages of fuel conversion were collected to study the gradual ash transformation. Characterization of the residual char and ash was performed employing SEM-EDS, XRD, and ICP with the support of thermodynamic equilibrium calculations (TECs). The results showed that the K and P present in the fuels were primarily found in the residual char and ash in all cases for all studied fuels. While the main part of the K release occurred during the char conversion stage, the main part of the P release occurred during the devolatilization stage. The highest releases – less than 18% of P and 35% of K – were observed at the highest studied temperature for all fuels. These elements were present in the residual ashes as K2Ca(CO3)2 and Ca5(PO4)3OH for poplar; K-Ca-rich silicates and phosphosilicates in mainly amorphous ash for grass; and an amorphous phase rich in K-Mg-phosphates for wheat grain residues.

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  • 38.
    Hunter, Amanda
    et al.
    University of Edinburgh.
    Unosson, Jon
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Bosson, Jenny A
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Langrish, Jeremy P
    University of Edinburgh.
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Raftis, Jennifer B
    University of Edinburgh.
    Miller, Mark R
    University of Edinburgh.
    Lucking, Andrew J
    University of Edinburgh.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Donaldson, Kenneth
    University of Edinburgh.
    Flapan, Andrew D
    University of Edinburgh.
    Pung, Louis
    University of Edinburgh.
    Sadiktsis, Ioannis
    Stockholm University.
    Masala, Silvia
    Stockholm University.
    Westerholm, Roger
    Stockholm University.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Newby, David E
    University of Edinburgh.
    Mills, Nicholas L
    University of Edinburgh.
    Effect of wood smoke exposure on vascular function and thrombus formation in healthy fire fighters2014In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 11, article id 62Article in journal (Refereed)
    Abstract [en]

    Background: Myocardial infarction is the leading cause of death in fire fighters and has been linked with exposure to air pollution and fire suppression duties. We therefore investigated the effects of wood smoke exposure on vascular vasomotor and fibrinolytic function, and thrombus formation in healthy fire fighters. Methods: In a double-blind randomized cross-over study, 16 healthy male fire fighters were exposed to wood smoke (~1 mg/m3 particulate matter concentration) or filtered air for one hour during intermittent exercise. Arterial pressure and stiffness were measured before and immediately after exposure, and forearm blood flow was measured during intra-brachial infusion of endothelium-dependent and -independent vasodilators 4–6 hours after exposure. Thrombus formation was assessed using the ex vivo Badimon chamber at 2 hours, and platelet activation was measured using flow cytometry for up to 24 hours after the exposure. Results: Compared to filtered air, exposure to wood smoke increased blood carboxyhaemoglobin concentrations (1.3% versus 0.8%; P < 0.001), but had no effect on arterial pressure, augmentation index or pulse wave velocity (P > 0.05 for all). Whilst there was a dose-dependent increase in forearm blood flow with each vasodilator (P < 0.01 for all), there were no differences in blood flow responses to acetylcholine, sodium nitroprusside or verapamil between exposures (P > 0.05 for all). Following exposure to wood smoke, vasodilatation to bradykinin increased (P = 0.003), but there was no effect on bradykinin-induced tissue-plasminogen activator release, thrombus area or markers of platelet activation (P > 0.05 for all). Conclusions: Wood smoke exposure does not impair vascular vasomotor or fibrinolytic function, or increase thrombus formation in fire fighters. Acute cardiovascular events following fire suppression may be precipitated by exposure to other air pollutants or through other mechanisms, such as strenuous physical exertion and dehydration.

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  • 39. Korhonen, Kimmo
    et al.
    Kristensen, Thomas Bjerring
    Falk, John
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersen, Christina
    Carvalho, Ricardo L.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Department of Environment and Planning, Centre for Environmental and Marine Studies, University of Aveiro, 3810-193, Aveiro, Portugal.
    Malmborg, Vilhelm
    Eriksson, Axel
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pagels, Joakim
    Svenningsson, Birgitta
    Komppula, Mika
    Lehtinen, Kari E. J.
    Virtanen, Annele
    Ice-nucleating ability of particulate emissions from solid-biomass-fired cookstoves: an experimental study2020In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 20, no 8, p. 4951-4968Article in journal (Refereed)
    Abstract [en]

    This research was part of the Salutary Umea Study of Aerosols in Biomass Cookstove Emissions (SUSTAINE) laboratory experiment campaign. We studied ice-nucleating abilities of particulate emissions from solid-fuel-burning cookstoves, using a portable ice nuclei counter, Spectrometer Ice Nuclei (SPIN). These emissions were generated from two traditional cookstove types commonly used for household cooking in sub-Saharan Africa and two advanced gasifier stoves under research to promote sustainable development alternatives. The solid fuels studied included biomass from two different African tree species, Swedish softwood and agricultural residue products relevant to the region. Measurements were performed with a modified version of the standard water boiling test on polydisperse samples from flue gas during burning and size-selected accumulation mode soot particles from a 15 m(3) aerosol-storage chamber. The studied soot particle sizes in nanometers were 250, 260, 300, 350, 400, 450 and 500. From this chamber, the particles were introduced to water-supersaturated freezing conditions (-32 to -43 degrees) in the SPIN. Accumulation mode soot particles generally produced an ice-activated fraction of 10 3 in temperatures 1-1.5 degrees C higher than that required for homogeneous freezing at fixed RHw = 115 %. In five special experiments, the combustion performance of one cookstove was intentionally modified. Two of these exhibited a significant increase in the ice-nucleating ability of the particles, resulting in a 10(3) ice activation at temperatures up to 5.9 degrees C higher than homogeneous freezing and the observed increased ice-nucleating ability. We investigated six different physico-chemical properties of the emission particles but found no clear correlation between them and increasing ice-nucleating ability. We conclude that the freshly emitted combustion aerosols form ice via immersion and condensation freezing at temperatures only moderately above homogeneous freezing conditions.

  • 40. Lucking, Andrew J
    et al.
    Lundbäck, Magnus
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Barath, Stefan L
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Mills, Nicholas L
    Sidhu, Manjit K
    Langrish, Jeremy P
    Boon, Nicholas A
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Badimon, Juan J
    Gerlofs-Nijland, Miriam E
    Cassee, Flemming R
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Donaldson, Kenneth
    Sandstrom, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Newby, David E
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Particle traps prevent adverse vascular and prothrombotic effects of diesel engine exhaust inhalation in men2011In: Circulation, ISSN 0009-7322, E-ISSN 1524-4539, Vol. 123, no 16, p. 1721-1728Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: In controlled human exposure studies, diesel engine exhaust inhalation impairs vascular function and enhances thrombus formation. The aim of the present study was to establish whether an exhaust particle trap could prevent these adverse cardiovascular effects in men.

    METHODS AND RESULTS: Nineteen healthy volunteers (mean age, 25±3 years) were exposed to filtered air and diesel exhaust in the presence or absence of a particle trap for 1 hour in a randomized, double-blind, 3-way crossover trial. Bilateral forearm blood flow and plasma fibrinolytic factors were assessed with venous occlusion plethysmography and blood sampling during intra-arterial infusion of acetylcholine, bradykinin, sodium nitroprusside, and verapamil. Ex vivo thrombus formation was determined with the use of the Badimon chamber. Compared with filtered air, diesel exhaust inhalation was associated with reduced vasodilatation and increased ex vivo thrombus formation under both low- and high-shear conditions. The particle trap markedly reduced diesel exhaust particulate number (from 150 000 to 300 000/cm(3) to 30 to 300/cm(3); P<0.001) and mass (320±10 to 7.2±2.0 μg/m(3); P<0.001), and was associated with increased vasodilatation, reduced thrombus formation, and an increase in tissue-type plasminogen activator release.

    CONCLUSIONS: Exhaust particle traps are a highly efficient method of reducing particle emissions from diesel engines. With a range of surrogate measures, the use of a particle trap prevents several adverse cardiovascular effects of exhaust inhalation in men. Given these beneficial effects on biomarkers of cardiovascular health, the widespread use of particle traps on diesel-powered vehicles may have substantial public health benefits and reduce the burden of cardiovascular disease.

  • 41.
    Löndahl, Jakob
    et al.
    Department of Physics, Division of Nuclear Physics, Lund University, Lund, Sweden.
    Swietlicki, Erik
    Department of Physics, Division of Nuclear Physics, Lund University, Lund, Sweden.
    Rissler, Jenny
    Department of Design Sciences, Division of Ergonomics and Aerosol Technology (EAT), Lund University, Lund, Sweden.
    Bengtsson, Agneta
    Department of Physics, Division of Nuclear Physics, Lund University, Lund, Sweden.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Experimental determination of the respiratory tract deposition of diesel combustion particles in patients with chronic obstructive pulmonary disease2012In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 9, p. 30-Article in journal (Refereed)
    Abstract [en]

    Background: Air pollution, mainly from combustion, is one of the leading global health risk factors. A susceptible group is the more than 200 million people worldwide suffering from chronic obstructive pulmonary disease (COPD). There are few data on lung deposition of airborne particles in patients with COPD and none for combustion particles. Objectives: To determine respiratory tract deposition of diesel combustion particles in patients with COPD during spontaneous breathing. Methods: Ten COPD patients and seven healthy subjects inhaled diesel exhaust particles generated during idling and transient driving in an exposure chamber. The respiratory tract deposition of the particles was measured in the size range 10-500 nm during spontaneous breathing. Results: The deposited dose rate increased with increasing severity of the disease. However, the deposition probability of the ultrafine combustion particles (< 100 nm) was decreased in COPD patients. The deposition probability was associated with both breathing parameters and lung function, but could be predicted only based on lung function. Conclusions: The higher deposited dose rate of inhaled air pollution particles in COPD patients may be one of the factors contributing to their increased vulnerability. The strong correlations between lung function and particle deposition, especially in the size range of 20-30 nm, suggest that altered particle deposition could be used as an indicator respiratory disease.

  • 42. Martinsson, J
    et al.
    Eriksson, A C
    Nielsen, I Elbaek
    Berg Malmborg, V
    Ahlberg, E
    Andersen, C
    Lindgren, R
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordin, E Z
    Brune, W H
    Svenningsson, B
    Swietlicki, E
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pagels, J H
    Impacts of Combustion Conditions and Photochemical Processing on the Light Absorption of Biomass Combustion Aerosol2015In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, no 24, p. 14663-14671Article in journal (Refereed)
    Abstract [en]

    The aim was to identify relationships between combustion conditions, particle characteristics, and optical properties of fresh and photochemically processed emissions from biomass combustion. The combustion conditions included nominal and high burn rate operation and individual combustion phases from a conventional wood stove. Low temperature pyrolysis upon fuel addition resulted in "tar-ball" type particles dominated by organic aerosol with an absorption Angstrom exponent (AAE) of 2.5-2.7 and estimated Brown Carbon contributions of 50-70% to absorption at the climate relevant aethalometer-wavelength (520 nm). High temperature combustion during the intermediate (flaming) phase was dominated by soot agglomerates with AAE 1.0-1.2 and 85-100% of absorption at 520 nm attributed to Black Carbon. Intense photochemical processing of high burn rate flaming combustion emissions in an oxidation flow reactor led to strong formation of Secondary Organic Aerosol, with no or weak absorption. PM1 mass emission factors (mg/kg) of fresh emissions were about an order of magnitude higher for low temperature pyrolysis compared to high temperature combustion. However, emission factors describing the absorption cross section emitted per kg of fuel consumed (m(2)/kg) were of similar magnitude at 520 nm for the diverse combustion conditions investigated in this study. These results provide a link between biomass combustion conditions, emitted particle types, and their optical properties in fresh and processed plumes which can be of value for source apportionment and balanced mitigation of biomass combustion emissions from a climate and health perspective.

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  • 43.
    Muala, Ala
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Nicklasson, Hanna
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Swietlicki, Erik
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pettersson, Esbjörn
    Bosson, Jenny
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Rissler, Jenny
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Löndahl, Jakob
    Respiratory Tract Deposition of Inhaled Wood Smoke Particles in Healthy Volunteers2015In: Journal of Aerosol Medicine, ISSN 1941-2711, E-ISSN 1941-2703, Vol. 28, no 4, p. 237-246Article in journal (Refereed)
    Abstract [en]

    Background: Respiratory tract deposition of air pollution particles is a key to their adverse health effects. This study was aimed to determine the size-resolved deposition fraction (DF) of sooty wood smoke particles in the lungs of healthy subjects. The type of wood smoke investigated is typical for household air pollution from solid fuels, which is among the largest environmental health problems globally.

    Methods: Twelve healthy volunteers inhaled diluted wood smoke from incomplete soot-rich combustion in a common wood stove. The DF of smoke particles (10–500 nm) was measured during three 15-min exposures in each subject during spontaneous breathing. Lung function was measured using standard spirometry.

    Results: The total DFs by particle number concentration were 0.34±0.08. This can be compared with DFs of 0.21–0.23 in healthy subjects during previous experiments with wood pellet combustion. For particle mass, the total DFs found in this study were 0.22±0.06. DF and breathing frequency were negatively correlated as expected from model calculations (p<0.01).

    Conclusions: The DF of the investigated sooty wood smoke particles was higher than for previously investigated particles generated during more efficient combustion of biomass. Together with toxicological studies, which have indicated that incomplete biomass combustion particles rich in soot and polycyclic aromatic hydrocarbons (PAHs) are especially harmful, these data highlight the health risks of inadequate wood combustion.

  • 44.
    Muala, Ala
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Rankin, Gregory
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sehlstedt, Maria
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Unosson, Jon
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Bosson, Jenny A.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Behndig, Annelie
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pettersson, Esbjörn
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Bergvall, Christoffer
    Westerholm, Roger
    Jalava, Pasi I.
    Happo, Mikko S.
    Uski, Oskari
    Hirvonen, Maija-Riitta
    Kelly, Frank J.
    Mudway, Ian S.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Acute exposure to wood smoke from incomplete combustion - indications of cytotoxicity2015In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 12, article id 33Article in journal (Refereed)
    Abstract [en]

    Background: Smoke from combustion of biomass fuels is a major risk factor for respiratory disease, but the underlying mechanisms are poorly understood. The aim of this study was to determine whether exposure to wood smoke from incomplete combustion would elicit airway inflammation in humans. Methods: Fourteen healthy subjects underwent controlled exposures on two separate occasions to filtered air and wood smoke from incomplete combustion with PM1 concentration at 314 mu g/m(3) for 3 h in a chamber. Bronchoscopy with bronchial wash (BW), bronchoalveolar lavage (BAL) and endobronchial mucosal biopsies was performed after 24 h. Differential cell counts and soluble components were analyzed, with biopsies stained for inflammatory markers using immunohistochemistry. In parallel experiments, the toxicity of the particulate matter (PM) generated during the chamber exposures was investigated in vitro using the RAW264.7 macrophage cell line. Results: Significant reductions in macrophage, neutrophil and lymphocyte numbers were observed in BW (p < 0.01, < 0.05, < 0.05, respectively) following the wood smoke exposure, with a reduction in lymphocytes numbers in BAL fluid (< 0.01. This unexpected cellular response was accompanied by decreased levels of sICAM-1, MPO and MMP-9 (p < 0.05, < 0.05 and < 0.01). In contrast, significant increases in submucosal and epithelial CD3+ cells, epithelial CD8+ cells and submucosal mast cells (p < 0.01, < 0.05, < 0.05 and < 0.05, respectively), were observed after wood smoke exposure. The in vitro data demonstrated that wood smoke particles generated under these incomplete combustion conditions induced cell death and DNA damage, with only minor inflammatory responses. Conclusions: Short-term exposure to sooty PAH rich wood smoke did not induce an acute neutrophilic inflammation, a classic hallmark of air pollution exposure in humans. While minor proinflammatory lymphocytic and mast cells effects were observed in the bronchial biopsies, significant reductions in BW and BAL cells and soluble components were noted. This unexpected observation, combined with the in vitro data, suggests that wood smoke particles from incomplete combustion could be potentially cytotoxic. Additional research is required to establish the mechanism of this dramatic reduction in airway leukocytes and to clarify how this acute response contributes to the adverse health effects attributed to wood smoke exposure.

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  • 45.
    Muala, Ala
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Rankin, Gregory
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sehlstedt, Maria
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Unosson, Jon
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Bosson, Jenny
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Behndig, Annelie
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pettersson, Esbjörn
    Bergvall, Christoffer
    Westerholm, Roger
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Kelly, Frank
    Mudway, Ian
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Bronchial mucosal inflammation in healthy subjects after exposure to wood smoke from incomplete combustionManuscript (preprint) (Other academic)
    Abstract [en]

    Indoor smoke from combustion of solid biomass fuel is a major risk factor for respiratory disease worldwide. The mechanisms by which wood smoke exhibits its effects on human health are not well understood. The aim of this study was to determine whether exposure to wood smoke produced from incomplete combustion would elicit an airway inflammatory response.

    Methods Fourteen healthy subjects underwent controlled chamber exposure on two occasions to filtered air and to sooty wood smoke (PM1 ~ 314 μg/m3), generated by a common Nordic wood stove firing birch logs. The study was performed with a double-blind randomized cross-over design and the subjects alternated between exercise (VE=20 L/min/m2) and rest at 15-minute intervals for 3 hours. Bronchoscopies were performed 24 hours after each exposure where bronchial wash (BW), bronchoalveolar lavage (BAL) and endobronchial biopsies were taken. Differential cell counts and soluble components were analyzed in BW and BAL. Bronchial mucosal biopsies were analyzed using immunohistochemistry. Blood tests for inflammatory markers were sampled pre-exposure as well as at 24 and 44-hour time points post-exposure. Spirometry and Fraction of exhaled nitric oxide (FENO) were performed before, immediately after and 24 hours after each exposure.

    Results There was a significant increase in submucosal and epithelial CD3+ lymphocytes (p<0.01 and <0.05 respectively), together with CD8+ cells in the epithelium (p<0.05) after exposure to wood smoke compared to filtered air. Mast cells were also significantly increased in the submucosa (p<0.01) after wood smoke exposure.

    There were significant reductions in macrophages, neutrophils and lymphocytes in BW after exposure to wood smoke compared to filtered air, accompanied by decreased levels of soluble Intercellular Adhesion Molecule-1 (sICAM-1), myeloperoxidase (MPO) and matrix metalloproteinase-9 (MMP-9). No significant effects on cell numbers or acute inflammatory markers were demonstrated in BAL fluid or peripheral blood. Lung function and FENO were not affected by exposure to wood smoke.

    Conclusions Wood smoke exposure caused a significant increase in bronchial epithelial and submucosal CD3+ lymphocytes together with an increase in mucosal mast cells. Further examination revealed a significant increase in CD8+ lymphocytes within the epithelium. Unexpectedly there were no indications of any neutrophilic airway response or recruitment of alveolar macrophages. BW cell numbers, MPO and MMP-9 levels were also significantly reduced after wood smoke exposure. Further research is needed to determine the precise role of these events in relationship to the adverse health effects attributed to wood smoke exposure.

  • 46.
    Muala, Ala
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sehlstedt, Maria
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Bion, Anne
    Renault Technocentre, Guyancourt, France.
    Österlund, Camilla
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Swedish Defence Research Agency, FOI, Umeå, Sweden.
    Bosson, Jenny A.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Behndig, Annelie F.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Bucht, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Swedish Defence Research Agency, FOI, Umeå, Sweden.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Mudway, Ian S.
    MRC-PHE Centre for Environment and Health, School of Biomedical Sciences, King’s College London, London, UK.
    Langrish, Jeremy P.
    BHF/University Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK .
    Couderc, Stephane
    Renault Technocentre, Guyancourt, France.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Assessment of the capacity of vehicle cabin air inlet filters to reduce diesel exhaust-induced symptoms in human volunteers2014In: Environmental Health, E-ISSN 1476-069X, Vol. 13, no 1, article id 16Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Exposure to particulate matter (PM) air pollution especially derived from traffic is associated with increases in cardiorespiratory morbidity and mortality. In this study, we evaluated the ability of novel vehicle cabin air inlet filters to reduce diesel exhaust (DE)-induced symptoms and markers of inflammation in human subjects.

    METHODS: Thirty healthy subjects participated in a randomized double-blind controlled crossover study where they were exposed to filtered air, unfiltered DE and DE filtered through two selected particle filters, one with and one without active charcoal. Exposures lasted for one hour. Symptoms were assessed before and during exposures and lung function was measured before and after each exposure, with inflammation assessed in peripheral blood five hours after exposures. In parallel, PM were collected from unfiltered and filtered DE and assessed for their capacity to drive damaging oxidation reactions in a cell-free model, or promote inflammation in A549 cells.

    RESULTS: The standard particle filter employed in this study reduced PM10 mass concentrations within the exposure chamber by 46%, further reduced to 74% by the inclusion of an active charcoal component. In addition use of the active charcoal filter was associated by a 75% and 50% reduction in NO2 and hydrocarbon concentrations, respectively. As expected, subjects reported more subjective symptoms after exposure to unfiltered DE compared to filtered air, which was significantly reduced by the filter with an active charcoal component. There were no significant changes in lung function after exposures. Similarly diesel exhaust did not elicit significant increases in any of the inflammatory markers examined in the peripheral blood samples 5 hour post-exposure. Whilst the filters reduced chamber particle concentrations, the oxidative activity of the particles themselves, did not change following filtration with either filter. In contrast, diesel exhaust PM passed through the active charcoal combination filter appeared less inflammatory to A549 cells.

    CONCLUSIONS: A cabin air inlet particle filter including an active charcoal component was highly effective in reducing both DE particulate and gaseous components, with reduced exhaust-induced symptoms in healthy volunteers. These data demonstrate the effectiveness of cabin filters to protect subjects travelling in vehicles from diesel exhaust emissions.

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  • 47.
    Muala, Ala
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Österdahl, Rebecka
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sehlstedt, Maria
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Rankin, Gregory
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Pourazar, Jamshid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Bosson, Jenny A.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Lopez, Natxo Garcia
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Thermochemical Energy Conversion Laboratory, Umeå University, Umeå, Sweden.
    Behndig, Annelie F.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Sandström, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Small airways effects of exposure to wood smoke2019In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 54Article in journal (Other academic)
  • 48.
    Mukarunyana, Brigitte
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, College of Science and Technology, University of Rwanda, P.O. Box 3900, Kigali, Rwanda.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kabera, Telesphore
    School of Engineering, College of Science and Technology, University of Rwanda, P.O. Box 3900, Kigali, Rwanda.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The ability of biochars from cookstoves to remove pharmaceuticals and personal care products from hospital wastewater2023In: Environmental Technology & Innovation, ISSN 2352-1864, Vol. 32, article id 103391Article in journal (Refereed)
    Abstract [en]

    Adequate treatment of wastewater to remove micropollutants constitutes a major concern globally. Despite this, large volumes of untreated wastewater are released into the environment, mainly due to the cost involved. Biochars have been suggested to have the potential to remove pharmaceuticals and personal care products (PPCP) from wastewater, but, adsorption potential needs to be investigated further. Production of biochars should also preferably be sustainable and based on low-cost materials. This study investigated the ability of nine biochars produced in three cookstoves and from three feedstocks. All biochars were characterized and then applied in adsorption experiments, based on authentic hospital effluent. Our analytical method included 32 pharmaceuticals and personal care products, and 28 of these were detected and quantified in hospital wastewater effluent samples. Some PPCP were present in relatively high concentrations (more than 24 µg/L). Adsorption experiments showed that the biochars used in the investigation had average removal rates (RR) ranging from 14.2% to 65.5%. Removal rates also varied between and within cookstoves and feedstock. Although cookstove biochars with a low surface area in this study generally showed lower removal rates, results from surface characterization were not detailed enough to correlate the physicochemical properties of the pollutants with the adsorption. Further characterizations are therefore needed to point out the most important parameters involved in PPCP adsorption on cookstove biochars.

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  • 49. Nazelius, Ida-Linn
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Hedman, Henry
    Samuelsson, Robert
    Ohman, Marcus
    Influence of Peat Addition to Woody Biomass Pellets on Slagging Characteristics during Combustion2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 7, p. 3997-4006Article in journal (Refereed)
    Abstract [en]

    Upgraded biofuels such as pellets, briquettes, and powder are today commonly used in small as well as large scale appliances. In order to cover an increasing fuel demand new materials such as bark, whole tree assortments, and peat are introduced. These materials have higher ash content which is why they are potentially more problematic compared with stem wood. In general, few studies can be found regarding cocombustion of peat and biomass and in particular where the slagging tendencies are discussed. The overall objective of this study was therefore to determine the influence of peat addition to woody biomass pellets on slagging characteristics. Two different peat assortments (peat A and B) were copelletized separately in four different dry matter levels (0-5-15-30 wt %) into stem wood and energy wood, respectively. Peat A was a traditional Scandinavian fuel peat, with a high ash and Si content (carex), and peat B had a low ash content and relatively high Ca/Si ratio (sphagnum) chosen for its special characteristics. The produced pellets were combusted in a commercial underfed pellet burner (15 kW) installed in a reference boiler. The collected deposits (bottom ash and slag) from the combustion experiments were chemically characterized by scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) and X-ray diffraction (XRD) regarding the elemental distribution and morphology and phase composition, respectively. In addition, the bottom ashes were characterized according to inductively coupled plasma atomic emission spectroscopy (ICP-AES). To interpret the experimental findings chemical equilibrium model calculations were performed. The slagging tendency increased when adding peat into the woody biomasses. Especially sawdust with its relatively low ash and Ca content was generally more sensitive for the different peat assortments. Cofiring with the relatively Si and ash rich peat A resulted in the most severe slagging tendency. A significant increment of the Si, Al, and Fe content and a significant decrement of the Ca content in the slag could be seen when increasing the content of peat A in both woody biomasses. The slagging tendency increased when adding peat A because high temperature melting Ca-Mg oxides react to form more low temperature melting Ca/Mg-Al-K silicates. The slagging tendency was significantly lower when adding the more ash poor peat B, with relatively high Ca/Si ratio, into the woody biomass fuels compared with the peat A mixtures. The slag from the peat B mixings had a slightly higher Ca content compared with the Si content and a clearly higher content of Ca compared with the peat A mixtures. There were still Ca-Mg oxides left in the bottom ash i.e. a less amount of sticky low temperature melting K-silicate rich melt was formed when peat B was added to the woody biomasses.

  • 50. Nazelius, Ida-Linn
    et al.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Rebbling, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Fuel indices for estimation of slagging of phosphorus-poor biomass in fixed bed combustion2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 1, p. 904-915Article in journal (Refereed)
    Abstract [en]

    The market for solid biofuels will grow rapidly during the coming years, and there will be a great demand for raw materials. This will force the existing fuel base to also cover wooden materials of lower qualities as well as agricultural raw materials and residues, which often show unfavorable ash-melting temperatures. This may lead to combustion-related problems. Thus, for the utilization of lower quality fuels, it is important to be able to predict potential fuel ash-related problems such as slagging. In light of this, the first objective of the present paper was to evaluate the applicability of previously defined indices for slagging of biomass fuels (phosphorus-poor) in fixed bed combustion. The evaluation showed that none of the previously suggested indices in the literature are suitable for qualitative (nor quantitative) prediction of slagging during fixed bed combustion of P-poor biomass fuels. Hence, a second objective was to develop improved novel fuel indices that can be applied to estimate the slagging of phosphorus-poor biomass in fixed bed combustion. The novel fuel indices give a qualitative prediction of the slagging tendency in biomass fixed bed combustion but still needs additional work to further extend the compositional range as well as to fine tune the indices' boundaries.

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