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  • 1. Abafe, Ovokeroye A.
    et al.
    Späth, Jana
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Buckley, Chris
    Stark, Annegret
    Pietruschka, Bjoern
    Martincigh, Bice S.
    LC-MS/MS determination of antiretroviral drugs in influents and effluents from wastewater treatment plants in KwaZulu-Natal, South Africa2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 200, p. 660-670Article in journal (Refereed)
    Abstract [en]

    South Africa has the largest occurrence of the human immune deficiency virus (HIV) in the world but has also implemented the largest antiretroviral (ARV) treatment programme. It was therefore of interest to determine the presence and concentrations of commonly used antiretroviral drugs (ARVDs) and, also, to determine the capabilities of wastewater treatment plants (WWTPs) for removing ARVDs. To this end, a surrogate standard based LC-MS/MS method was optimized and applied for the detection of thirteen ARVDs used in the treatment and management of HIV/acquired immune deficiency syndrome (HIV/AIDS) in two major and one modular WWTP in the eThekwini Municipality in KwaZulu-Natal, South Africa. The method was validated and the detection limits fell within the range of 2–20 ng L−1. The analytical recoveries for the ARVDs were mainly greater than 50% with acceptable relative standard deviations. The concentration values ranged from <LOD – 53000 ng L−1 (influent), <LOD – 34000 ng L−1 (effluent) in a decentralized wastewater treatment facility (DEWATS); <LOD – 24000 ng L−1 (influent), <LOD – 33000 ng L−1 (effluent) in Northern WWTP and 61–34000 ng L−1 (influent), <LOD – 20000 ng L−1 (effluent) in Phoenix WWTP. Whilst abacavir, lamivudine and zidovudine were almost completely removed from the effluents, atazanavir, efavirenz, lopinavir and nevirapine persisted in the effluents from all three WWTPs. To estimate the ecotoxicological risks associated with the discharge of ARVDs, a countrywide survey focussing on the occurrence of ARVDs in WWTPs, surface and fresh water bodies, and aquatic organisms, is necessary.

  • 2.
    Allegrini, Elisa
    et al.
    Technical University of Denmark, Department of Environmental Engineering.
    Boldrin, Alessio
    Tech Univ Technical University of Denmark, Department of Environmental Engineering.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundtorp, Kasper
    Babcock & Wilcox Vølund A/S, Göteborg, Sweden.
    Fruergaard Astrup, Thomas
    Technical University of Denmark, Department of Environmental Engineering.
    Quality and generation rate of solid residues in the boiler of a waste-to-energy plant2014In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 270, p. 127-136Article in journal (Refereed)
    Abstract [en]

    The Danish waste management system relies significantly on waste-to-energy (WtE) plants. The ash produced at the energy recovery section (boiler ash) is classified as hazardous waste, and is commonly mixed with fly ash and air pollution control residues before disposal. In this study, a detailed characterization of boiler ash from a Danish grate-based mass burn type WtE was performed, to evaluate the potential for improving ash management. Samples were collected at 10 different points along the boiler's convective part, and analysed for grain size distribution, content of inorganic elements, polychlorinated dibenzo-. p-dioxins and dibenzofurans (PCDD and PCDF), and leaching of metals. For all samples, PCDD and PCDF levels were below regulatory limits, while high pH values and leaching of e.g. Cl were critical. No significant differences were found between boiler ash from individual sections of the boiler, in terms of total content and leaching, indicating that separate management of individual ash fractions may not provide significant benefits. 

  • 3. Altarawneh, Mohammednoor
    et al.
    Saeed, Anam
    Siddique, Kamal
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Dlugogorski, Bogdan Z.
    Formation of polybrominated dibenzofurans (PBDFs) and polybrominated diphenyl ethers (PBDEs) from oxidation of brominated flame retardants (BFRs)2020In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 400, article id 123166Article in journal (Refereed)
    Abstract [en]

    Brominated aromatic rings constitute main structural entities in virtually all commercially deployed brominated flame retardants (BFRs). Oxidative decomposition of BFRs liberates appreciable quantities of bromobenzenes (BBzs). This contribution reports experimental measurements for the generation of notorious polybrominated dibenzofurans (PBDFs) and polybrominated diphenyl ethers (PBDEs) from oxidation of monobromobenzene (MBBz). In the light of developed product profiles, we map out reaction pathways and report kinetic parameters for PBDFs and PBDEs formation from coupling reactions of MBBz molecule and its derived ortho-bromophenoxy (o-BPhxy) radical using quantum chemical calculations. The identification and quantitation of product species involve the use of gas chromatograph - triple quadrupole mass spectrometer (GC-QQQMS) operating in the multiple reaction monitoring (MRM) mode. Bimolecular reactions of MBBz and o-BPhxy result in the generation of twelve pre-PBDF intermediates, of which four can also serve as building blocks for the synthesis of PBDEs. These four intermediates are denoted as pre-PBDE/pre-PBDF, with the remaining eight symbolised as pre-PBDF. The resonance-stabilised structure of the o-BPhxy radical accumulates more spin density character on its phenoxy O atom (30.9 %) in reference to ortho-C and para-C sites. Thus, the formation of the pre-PBDE/pre-PBDF structures via O/o-C couplings advances faster as it requires lower activation enthalpies (79.2 – 84.9 kJ mol−1) than the pre-PBDF moieties, which arise via pairing reactions involving o-C(H or Br)/o-C(H or Br) sites (97.2 – 180.2 kJ mol−1). Kinetic analysis indicates that, the O/o-C pre-PBDE/pre-PBDF adducts self-eject the out-of-plane H atoms to produce PBDEs, rather than undergo a three-step mechanism forming PBDFs. However, experimental measurements demonstrate PBDEs appearing in lower yields as compared to those of PBDFs; presumably due to H- and Br-induced conversion of the PBDEs into PBDFs following a simple ring-closure reaction. High reaction temperatures facilitate loss of ortho Br atom from PBDEs, followed by cyclisation step to generate PBDFs. PBDFs are observed in a narrow temperature range of 700–850 °C, whereas PBDEs form between 550–850 °C. Since formation mechanisms of PBDFs and polybrominated dibenzo-p-dioxins (PBDDs) are typically only sensitive to the bromination at ortho positions, the results reported herein apply also to higher brominated isomers of BBzs.

  • 4.
    Aurell, Johanna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Effects of quench time profiles on PCDD/F formation in the postcombustion zone during municipal solid waste incineration2009In: Environmental Engineering Science, ISSN 1092-8758, E-ISSN 1557-9018, Vol. 26, no 3, p. 541-550Article in journal (Refereed)
    Abstract [en]

    Effects of postcombustion zone temperatures and flue gas residence times on monochlorinated to octachlorinated dibenzo-p-dioxins and -furans (PCDD/F) in a laboratory-scale reactor combusting municipal solid waste were investigated. Four different quench time profiles were investigated, falling from 400°C to 200°C, 300°C to 100°C, 450°C to 200°C and 460°C to 260°C, with corresponding residence times of 1.4 to 4.4sec, 1.4 to 5.4sec, 1.3 to 4.3sec, and 1.3 to 4.0sec, respectively. Flue gas samples were collected simultaneously at three fixed sampling points, with an additional sampling of flue gas entering the postcombustion zone (640°C). The quench time profiles resulted in different total PCDD/F yields, as well as differences in homologue profiles and congener patterns. Thus, the formation pathways seem to be dependent on sufficient residence time within a specific temperature region. Formation of PCDD/F was shown to be rapid and mainly located to the 640°C to 400°C temperature region, with non-detectable levels at 640°C and concentrations at 400°C that did not increase or decrease significantly downstream. Furthermore, a prolonged residence time at and above 450°C/ 460°C showed low yields even downstream the postcombustion zone compared to the 400°C to 200°C and 300°C to 100°C profiles. The 460°C to 260°C profile resulted in increased abundance at the last two sampling points of PCDD congeners known to correlate with 2,4,6-trichlorophenols, suggesting that chlorophenol condensation reactions were promoted by this quench time profile.

  • 5.
    Aurell, Johanna
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Formation of Dioxins in a Modified Laboratory-Scale Fluidize-Bed Reactor During a Long-Term MSW Combustion Experiment2006In: Organohalogen Compounds, Vol. 68, p. 1205-8Article in journal (Refereed)
  • 6.
    Benavente, Veronica
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lage, Sandra
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden; Department of Environmental Science, Stockholm University, Stockholm, Sweden.
    Gentili, Francesco G.
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Influence of lipid extraction and processing conditions on hydrothermal conversion of microalgae feedstocks – Effect on hydrochar composition, secondary char formation and phytotoxicity2022In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 428, article id 129559Article in journal (Refereed)
    Abstract [en]

    This study investigated the effect of lipid extraction of microalgae feedstocks subjected to hydrothermal carbonization (HTC) with regard to the carbonization degree, chemical composition and phytotoxicity of hydrochars produced under different reaction temperatures and residence times. Special attention was given to the formation and composition of secondary char, as this part of the hydrochar may be of particular importance for environmental and technical applications. A microalgae polyculture grown in municipal wastewater was extracted to retrieve lipids, and both unextracted (MA) and extracted microalgae (EMA) were used to produce hydrochars at 180–240 °C for 1–4 h. The composition of the hydrochars was thoroughly characterized by elemental analysis, thermogravimetric analysis and pyrolysis–gas chromatography/mass spectrometry analysis. MA exhibited a greater carbonization degree than EMA and contained higher amounts of secondary char under the same processing conditions. During the carbonization of EMA, more decomposition products remained in the liquid phase and less polymerization occurred than for MA, which explained the lower solid yield of EMA-derived hydrochars in comparison to MA hydrochars. Consequently, although they contained potentially toxic substances (i.e., carboxylic acids, aldehydes and ketones), the EMA-derived hydrochars exhibited a lower phytotoxic potential. This indicates that low-temperature hydrochars containing less than 10% of extractives might be suitable as soil amendments, whereas extractive-rich hydrochars would be more appropriate for other long-term applications, such as adsorbents for contaminant removal, energy storage and composite materials. Detailed characterization of microalgae-derived hydrochars is required to enable the most suitable application areas to be identified for these materials, and thereby make full use of their function as carbon sinks.

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  • 7.
    Benavente, Veronica
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. RISE Processum AB, Hörneborgsvägen 10, Örnsköldsvik, Sweden.
    Pérez, Carla
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Doctoral School, Umeå University, Umeå, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Co-hydrothermal carbonization of microalgae and digested sewage sludge: Assessing the impact of mixing ratios on the composition of primary and secondary char2024In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 174, p. 429-438Article in journal (Refereed)
    Abstract [en]

    The role of microalgae cultivation in wastewater treatment and reclamation has been studied extensively, as has the potential utility of the resulting algal biomass. Most methods for processing such biomass generate solid residues that must be properly managed to comply with current sustainable resource utilization requirements. Hydrothermal carbonization (HTC) can be used to process both individual wet feedstocks and mixed feedstocks (i.e., co-HTC). Here, we investigate co-HTC using microalgae and digested sewage sludge as feedstocks. The objectives were to (i) study the material's partitioning into solid and liquid products, and (ii) characterize the products’ physicochemical properties. Co-HTC experiments were conducted at 180–250°C using mixed microalgae/sewage sludge feedstocks with the proportion of sewage sludge ranging from 0 to 100 %. Analyses of the hydrochar composition and the formation and composition of secondary char revealed that the content of carbonized material in the product decreased as the proportion of sewage sludge in the feedstock increased under fixed carbonization conditions. The properties of the hydrochars and the partitioning of material between the liquid phase and the hydrochar correlated linearly with the proportion of microalgae in mixed feedstocks, indicating that adding sewage sludge to microalgae had weak or non-existent synergistic effects on co-HTC outcomes. However, the proportion of sewage sludge in the feedstock did affect the secondary char. For example, adding sewage sludge reduced the abundance of carboxylic acids and ketones as well as the concentrations of higher molecular weight cholesterols. Such changes may alter the viable applications of the hydrochar.

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  • 8.
    Bergknut, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Laudon, Hjalmar
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, Anna
    Gocht, Tilman
    Wiberg, Karin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Atmospheric deposition, retention, and stream export of dioxins and PCBs in a pristine boreal catchment2011In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 159, no 6, p. 1592-1598Article in journal (Refereed)
    Abstract [en]

    The mass-balance between diffuse atmospheric deposition of organic pollutants, amount of pollutants retained by the terrestrial environment, and levels of pollutants released to surface stream waters was studied in a pristine northern boreal catchment. This was done by comparing the input of atmospheric deposition of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs with the amounts exported to surface waters. Two types of deposition samplers were used, equipped with a glass fibre thimble and an Amberlite sampler respectively. The measured fluxes showed clear seasonality, with most of the input and export occurring during winter and spring flood, respectively. The mass balance calculations indicates that the boreal landscape is an effective sink for PCDD/Fs and PCBs, as 96.0-99.9 % of received bulk deposition was retained, suggesting that organic pollutants will continue to impact stream water in the region for an extended period of time.

  • 9.
    Björklund, Sofie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weidemann, Eva
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Emission of per- and polyfluoroalkyl substances from a waste-to-energy plant-occurrence in ashes, treated process water, and first observation in flue gas2023In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 57, no 27, p. 10089-10095Article in journal (Refereed)
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are a large group of compounds commonly used as industrial chemicals and constituents of consumer products, e.g., as surfactants and surface protectors. When products containing PFASs reach their end of life, some end up in waste streams sent to waste-to-energy (WtE) plants. However, the fate of PFASs in WtE processes is largely unknown, as is their potential to enter the environment via ash, gypsum, treated process water, and flue gas. This study forms part of a comprehensive investigation of the occurrence and distribution of PFASs in WtE residues. Sampling was performed during incineration of two different waste mixes: normal municipal solid waste incineration (MSWI) and incineration of a waste mix with 5-8 wt % sewage sludge added to the MSWI (referred to as Sludge:MSWI). PFASs were identified in all examined residues, with short-chain (C4-C7) perfluorocarboxylic acids being the most abundant. Total levels of extractable PFASs were higher during Sludge:MSWI than during MSWI, with the total annual release estimated to be 47 and 13 g, respectively. Furthermore, PFASs were detected in flue gas for the first time (4.0-5.6 ng m-3). Our results demonstrate that some PFASs are not fully degraded by the high temperatures during WtE conversion and can be emitted from the plant via ash, gypsum, treated process water, and flue gas.

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  • 10.
    Björklund, Sofie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weidemann, Eva
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå Energi AB, Umeå, Sweden.
    Yeung, Leo W.
    Man-Technology-Environment Research Centre (MTM), School of Science and Technology, Örebro University, Örebro, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Occurrence of per- and polyfluoroalkyl substances and unidentified organofluorine in leachate from waste-to-energy stockpile: a case study2021In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 278, article id 130380Article in journal (Refereed)
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are a diverse group of chemicals used in consumer products, which will inevitably end up in waste streams. Landfills are widely recognized secondary point sources of PFASs, but other types of waste management sites have received less attention. Therefore, in a case study presented here we investigated releases of PFASs from temporarily stored waste by determining quantities of 34 PFASs in leachate from a Waste-to-Energy stockpile (45 000 ± 2000 tonnes) during five months in 2019. We also measured extractable organofluorine (EOF) to account for PFASs not included in the target list. The mean total concentration of the 34 PFAS (Σ34PFAS) was 211 ± 31 ng/L, and short-chain (C4–C7) perfluorocarboxylic acids (PFCAs) accounted for 56–60% of the total. Moreover, we found that Σ34PFAS only accounted for 12% ± 4% of EOF detected in the leachate. Our results demonstrate that waste stockpiles are previously unexplored sources of PFASs in the environment, and the dominance of short-chain PFCAs is consistent with observed profiles of contaminants in landfill leachates.

  • 11. Buss, Wolfram
    et al.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mašek, Ondřej
    Unexplored potential of novel biochar-ash composites for use as organo-mineral fertilizers2019In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 208, p. 960-967Article in journal (Refereed)
    Abstract [en]

    Application of wood ash on forest and agricultural soils can provide nutrients and increase soil pH, however, it changes the soil chemistry rapidly and temporarily, often resulting in reduced plant growth and potassium leaching. Biochar from woody materials are nutrient poor and need nutrient enhancement prior to soil application. In this study, spruce residues were mixed with spruce/pine ash in different ratios (0–50%) to produce biochar-ash composites at 450 °C. The biochar yield (ash-free basis) increased by 80–90% with the addition of 50% ash due to catalytic biochar formation. Consequently, nearly half the amount of wood is needed to produce the same amount of (ash-free) biochar. Mineral release was moderated in the composites compared to pure ash, demonstrated by a lower electric conductivity and % available K content (a factor of 2.5–4.4 lower than in wood ash). Furthermore, the % available chromium content, which is a key potentially toxic element in wood ash, decreased by a factor of 50–160. Soil application of biochar-ash composites decreases the risk of Cr toxicity, salinity stress and leaching of K in soil substantially compared to ash application. Biochar-ash composites are a novel product with vast unexplored potential for use in forestry and agriculture.

  • 12. Buss, Wolfram
    et al.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wurzer, Christian
    Masek, Ondrej
    Synergies between BECCS and Biochar-Maximizing Carbon Sequestration Potential by Recycling Wood Ash2019In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 7, no 4, p. 4204-4209Article in journal (Refereed)
    Abstract [en]

    Bioenergy carbon capture and storage (BECCS) and biochar are key carbon-negative technologies. In this study, synergies between these technologies were explored by using ash from wood combustion, a byproduct from BECCS, as an additive (0, 5, 10, 20, and 50 wt %) in biochar production (wood pyrolysis at 450 degrees C). The addition of wood ash catalyzed biochar formation and increased the yield of fixed carbon (FC) (per dry, ash-free feedstock), i.e., the sequestrable carbon per spruce wood input. At the highest ash addition (50%), 45% less wood was needed to yield the same amount of FC. Since the land area available for growing biomass is becoming scarcer, our approach significantly increases biochar's potential to sequester carbon. However, increasing the feedstock ash content results in less feedstock carbon available for conversion into FC. Consequently, the yield of FC per pyrolysis run (based on dry feedstock) in the 50% ash-amended material was lower than in the control. An economic analysis showed that the 20% ash-amended biochar brings the biggest cost savings over the control with a 15% decrease in CO2-abatement costs. Biochar-ash composites increase the carbon sequestration potential of biochar significantly, reduce the CO2-abatement costs, and recycle nutrients which can result in increased plant growth in turn and more biomass for BECCS, bringing synergies for BECCS and biochar deployment.

  • 13.
    Duong Phan, Ngoc Chau
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weidemann, Eva
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundin, Lisa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Swedish University of Agricultural Sciences.
    Accurate sampling of PCDD/F in high temperature flue-gas using cooled sampling probes2012In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 88, no 7, p. 832-836Article in journal (Refereed)
    Abstract [en]

    In a laboratory-scale combustion reactor, flue-gas samples were collected at two temperatures in the post-combustion zone, 700 °C and 400 °C, using two different water-cooled sampling probes. The probes were the cooled probe described in the European Standard method EN-1948:1, referred to as the original probe, and a modified probe that contained a salt/ice mixture to assist the cooling, referred to as the sub-zero probe. To determine the efficiency of the cooling probes, internal temperature measurements were recorded at 5 cm intervals inside the probes. Flue-gas samples were analyzed for polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). Samples collected at 700 °C using the original cooling probe showed higher concentrations of PCDD/Fs compared to samples collected using the sub-zero probe. No significant differences were observed between samples collected at 400 °C. The results indicated that artifact formation of PCDD/Fs readily occurs during flue-gas sampling at high temperatures if the cooling within the probe is insufficient, as found for the original probe at 700 °C. It was also shown that this problem could be alleviated by using probes with an enhanced cooling capacity, such as the sub-zero probe.

    Although this may not affect samples collected for regulatory purposes in exit gases, it is of great importance for research conducted in the high-temperature region of the post-combustion zone. 

  • 14.
    Edo Gimenez, Mar
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Energy Engineering, Department of Engineering Sciences & Mathematics, Luleå University of Technology, Luleå, Sweden.
    Gao, Qiuju
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Persson, Per-Erik
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fate of metals and emissions of organic pollutants from torrefaction of waste wood, MSW, and RDF2017In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 68, p. 646-652Article in journal (Refereed)
    Abstract [en]

    Torrefaction of municipal solid waste (MSW), refuse-derived fuel (RDF), and demolition and construction wood (DC) was performed at 220°C and a residence time of 90 min in a bench-scale reactor. The levels of toxic polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) contained in emission from the torrefaction process were evaluated. In addition, main ash-forming elements and trace metals in the raw feedstock and char were determined. The use of MSW in fuel blends with DC resulted in lower PCDD and PCDF emissions after torrefaction, compared with the RDF blends. The migration of chlorine from the feedstock to the gas phase reduces the chlorine content of the char which may reduce the risk of alkali chloride-corrosion in char combustion. However, trace metals catalytically active in the formation of PCDD and PCDF remain in the char, thereby may promote PCDD and PCDF formation during subsequent char combustion for energy recovery; this formation is less extensive than when the feedstock is used.

  • 15.
    Edo, Mar
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Persson, Per-Erik
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Assessment of chemical and material contamination in waste wood fuels: a case study ranging over nine years2016In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 49, p. 311-319Article in journal (Refereed)
    Abstract [en]

    The increased demand for waste wood (WW) as fuel in Swedish co-combustion facilities during the last years has increased the import of this material. Each country has different laws governing the use of chemicals and therefore the composition of the fuel will likely change when combining WW from different origins. To cope with this, enhanced knowledge is needed on WW composition and the performance of pre-treatment techniques for reduction of its contaminants. In this study, the chemical and physical characteristics of 500 WW samples collected at a co-combustion facility in Sweden between 2004 and 2013 were investigated to determine the variation of contaminant content over time. Multivariate data analysis was used for the interpretation of the data. The concentrations of all the studied contaminants varied widely between sampling occasions, demonstrating the highly variable composition of WW fuels. The efficiency of sieving as a pre-treatment measure to reduce the levels of contaminants was not sufficient, revealing that sieving should be used in combination with other pre-treatment methods. The results from this case study provide knowledge on waste wood composition that may benefit its management. This knowledge can be applied for selection of the most suitable pre-treatments to obtain high quality sustainable WW fuels.

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  • 16.
    Edo, Mar
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Budarin, Vitaliy
    Aracil, Ignacio
    Persson, Per-Erik
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The combined effect of plastics and food waste accelerates the thermal decomposition of refuse-derived fuels and fuel blends2016In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 180, p. 424-432Article in journal (Refereed)
    Abstract [en]

    Mechanical treatments such as shredding or extrusion are applied to municipal solid wastes (MSW) to produce refuse-derived fuels (RDF). In this way, a waste fraction (mainly composed by food waste) is removed and the quality of the fuel is improved. In this research, simultaneous thermal analysis (STA) was used to investigate how different mechanical treatments applied to MSW influence the composition and combustion behaviour of fuel blends produced by combining MSW or RDF with wood in different ratios. Shredding and screening resulted in a more efficient mechanical treatment than extrusion to reduce the chlorine content in a fuel, which would improve its quality. This study revealed that when plastics and food waste are combined in the fuel matrix, the thermal decomposition of the fuels are accelerated. The combination of MSW or RDF and woody materials in a fuel blend has a positive impact on its decomposition.

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  • 17.
    Edo, Mar
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ortuño, Núria
    Persson, Per-Erik
    Conesa, Juan A.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Emissions of toxic pollutants from co-combustion of demolition and construction wood and household waste fuel blends2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 203, p. 506-513Article in journal (Refereed)
    Abstract [en]

    Four different types of fuel blends containing demolition and construction wood and household waste were combusted in a small-scale experimental set-up to study the effect of fuel composition on the emissions of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), chlorobenzenes (PCBzs), chlorophenols (PCPhs) and polycyclic aromatic hydrocarbons (PAHs). Two woody materials, commercial stemwood (ST) and demolition and construction wood (DC) were selected because of the differences in their persistent organic pollutants (POPs), ash and metals content. For household waste, we used a municipal solid waste (MSW) and a refuse-derived fuel (RDF) from MSW with 5-20 wt% and up to 5 wt% food waste content respectively. No clear effect on the formation of pollutants was observed with different food waste content in the fuel blends tested. Combustion of ST-based fuels was very inefficient which led to high PAH emissions (32 +/- 3.8 mg/kg(fuel)). The use of DC clearly increased the total PCDD and PCDF emissions (71 +/- 26 mu g/kg(fuel)) and had a clear effect on the formation of toxic congeners (210 +/- 87 ng WHO2005-TEQ/kg(fuel)). The high PCDD and PCDF emissions from DC-based fuels can be attributed to the presence of material contaminants such as small pieces of metals or plastics as well as timber treated with chromated copper arsenate preservatives and pentachlorophenol in the DC source. 

  • 18.
    Egan Sjölander, Annika
    et al.
    Umeå University, Faculty of Arts, Department of culture and media studies.
    Nordlund, Annika
    Umeå University, Faculty of Social Sciences, Department of Psychology. Umeå University, Faculty of Social Sciences, Department of Geography and Economic History, Economic and social geography, Transportation Research Unit (TRUM).
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The multiple meanings of water: wastewater treatment and reuse seen from a communication perspective2018Conference paper (Other academic)
  • 19.
    Gao, Qiuju
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Budarin, Vitaliy L.
    Cieplik, Mariusz
    Gronnow, Mark
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    PCDDs, PCDFs and PCNs in products of microwave-assisted pyrolysis of woody biomass: Distribution among solid, liquid and gaseous phases and effects of material composition2016In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 145, p. 193-199Article in journal (Refereed)
    Abstract [en]

    Microwave-assisted pyrolysis (MAP) of lignocellulosic biomass is a technique that could potentially be used to produce and upgrade renewable energy carriers. However, there is no available information about the formation of dioxins and other organic pollutants in MAP treatment of woody biomass. In this study, MAP experiments were conducted in lab-scale using virgin softwood, bark, and impregnated wood as feedstocks. The non-condensable gas, liquid (fractionated into aqueous and oil phases), and char fractions generated during pyrolysis were collected and analysed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs). The concentrations of PCDDs, PCDFs and PCNs in the pyrolysis products ranged from 0.52 to 43.7 ng kg(-1). All investigated compound groups were most abundant in the oil fraction, accounting for up to 68% (w/w) of the total concentrations. The highest PCDD, PCDF and PCN concentrations were found from the pyrolysis of bark, which has relatively high contents of chlorine and mineral matter, followed by impregnated wood, which contains organic and metal-based preservatives. The homologue profiles of all three compound groups were dominated by the less chlorinated homologues. The homologue abundance decreased as the degree of chlorination increased. This trend was observed for all three feedstocks.

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  • 20.
    Gao, Qiuju
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cieplik, Mariusz K
    Budarin, Vitaliy L
    Gronnow, Mark
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mechanistic evaluation of polychlorinated dibenzo-p-dioxin, dibenzofuran and naphthalene isomer fingerprints in microwave pyrolysis of biomass2016In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 150, p. 168-175Article in journal (Refereed)
    Abstract [en]

    Isomer distribution patterns of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) were investigated in microwave-assisted pyrolysis (MAP) products of woody biomass. The feedstocks included bark and impregnated wood. The results indicated that isomer distributions in MAP are more selective compared to those reported from wood burning and waste incineration. Favored formation of 4-MoCDF and highly selective chlorine substitution at the 2,4-position observed during MAP suggested a preferred formation pathway of PCDFs involving (chloro)phenol precursors followed by subsequent chlorination. The PCDD distribution was dominated by isomers typically formed from chlorophenol condensation at relatively low temperature. The PCN isomer distributions showed a tendency for sequential chlorination from non-substituted naphthalene at successive positions. The presence of isomers such as 1-MoCDD, 4-MoCDF, 1,2,3-TriCN with low thermodynamic stability indicates that kinetic factors may be important in the MAP process.

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  • 21.
    Gao, Qiuju
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edo, M
    Larsson, S. H.
    Collina, E
    Rudolfsson, M
    Gallina, M
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Physical transformation and formation of PCDDs and PCDFs in torrefaction of biomass with different chemical compositionManuscript (preprint) (Other academic)
  • 22.
    Gao, Qiuju
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edo, Mar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, Sylvia H.
    Collina, Elena
    Rudolfsson, Magnus
    Gallina, Marta
    Oluwoye, Ibukun
    Altarawneh, Mohammednoor
    Dlugogorski, Bogdan Z.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formation of PCDDs and PCDFs in the torrefaction of biomass with different chemical composition2017In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 123, p. 126-133Article in journal (Refereed)
    Abstract [en]

    Torrefaction is a thermal pre-treatment technology used to refine biomass, mainly for energy production purposes. However, there is currently a lack of information on the potential formation of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in the torrefaction process. In this study, torrefaction was conducted using five different types of feedstock: stemwood, bark, wood from a discarded telephone pole, cassava stems and particle board. The feedstock as well as the torrefied biomass (chars) and the volatiles (non-condensable and condensable) generated during torrefaction were analyzed for PCDDs and PCDFs. PCDD concentrations in the torrefaction products were about 2-5 fold of those in the feedstocks. Torrefaction of particle board resulted in extensive formation of PCDDs (7200 ng kg(-1)) compared to the other four feedstocks (13-27 ng kg(-1)). Examination of the homologue profiles suggested that the observed PCDDs in the torrefaction products partly originated from new formation and partly physical transformation from volatilization and re-condensation of PCDDs present in the feedstock. Dechlorination of highly chlorinated compounds (HpCDD and OCDD) in the feedstock to form less chlorinated PCDDs was also observed. Compared to PCDDs, the net formation of PCDFs in the torrefaction process was low, except for the telephone pole sample, for which a dramatic increase (44-fold) of PCDFs was observed. PCDDs and PCDFs were mainly retained in the chars, accounting for 76-96% and 39-74% of the total concentration, respectively. It was also found that the highly chlorinated congeners tended to be retained in the chars, whereas the less chlorinated ones were predominantly volatilized into the gas phase.

  • 23.
    Gao, Qiuju
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pommer, Linda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Evaluation of solvent for pressurized liquid extraction of PCDD, PCDF, PCN, PCBz, PCPh and PAH in torrefied woody biomass2015In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 154, p. 52-58Article in journal (Refereed)
    Abstract [en]

    Biomass torrefaction for sustainable energy production has gained an increasing interest. However, there is a lack of information on the thermal formation of persistent organic pollutants such as dioxins in the torrefied solid product. In this paper, we investigated the applicability of pressurized liquid extraction (PLE) for simultaneous extraction of a number of polychlorinated planar aromatic compounds from torrefied wood. The targeted compounds included polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), benzenes (PCBz), phenols (PCPhs) and PAHs. PLE tests were conducted on torrefied and non-torrefied (i.e. raw) eucalyptus wood chips using 5 single solvents (n-hexane, toluene, dichloromethane, acetone and methanol) and a mixture of n-hexane/toluene (1:1, v/v). The performance of each solvent was evaluated in terms of recoveries of spiked internal standards and the amount of co-extracted sample matrix. High polarity solvents such as methanol and acetone resulted in poor recoveries from torrefied wood for most of the target compounds, probably due to the high co-extraction of thermally degraded lignocellulosic compounds. Raw wood was less solvent-dependent and comparable results were obtained for polar and non-polar solvents. Toluene showed the best performance of the investigated solvents, with average recoveries of 79 +/- 14% and 66 +/- 9% for raw and torrefied wood, respectively. The method was validated using pentachlorophenol-tainted spruce wood chips. The proposed PLE method was compared to the traditional Soxhlet method. Results show that PLE gave equivalent or better extraction for all target compounds.

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  • 24. Hou, Song
    et al.
    Dlugogorski, Bogdan Z.
    Mackie, John C.
    Kennedy, Eric M.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Altarawneh, Mohammednoor
    Oxidation of 4-bromo-4'-chlorobiphenyl, model species for forming mixed halogenated aromatic compounds2017In: International Journal of Environment and Pollution, ISSN 0957-4352, E-ISSN 1741-5101, Vol. 61, no 3-4, p. 243-260Article in journal (Refereed)
    Abstract [en]

    This contribution reports results from the gas-phase oxidation of 4-bromo-4'-chlorobiphenyl (4,4'-BCB) in order to fathom the formation of toxic species produced during the combustion of mixed halogenated aromatics. In their own right, mixed polybrominated/polychlorinated biphenyls (PXBs) represent a new class of environmental contaminants, recently detected in food and human tissues. Gas chromatography-quadrupole mass spectrometry (GC-QMS), gas chromatography-quadrupole time of flight mass spectrometry (GC-QTOFMS), Fourier transform infrared spectroscopy (FTIR) and ion chromatography (IC) served to analyse the volatile and semi-volatile organic compounds (V/SVOCs), including mixed halogenated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs), and gaseous products including HBr/HCl. The selection of non-ortho substituted PXB as a model species yields a large number of halogenated compounds, including monochloro- and monobromobenzene and higher halogenated benzenes and naphthalenes and derivatives of halogenated benzenes (such as 1-chloro-4-ethynylbenzene). We also detect small amounts of chlorinated and mixed halogenated dibenzofurans. The present study provides insights into the formation of several classes of halogenated and mixed-halogenated pollutants in combustion processes involving both bromine and chlorine sources, such as those of brominated flame retardants and PVC plastics.

  • 25.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formation of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and naphthalenes (PCN) in a laboratory-scale waste combustion reactor2011In: Heterogeneous combustion / [ed] George I. Stoev, Nova Science Publishers, Inc., 2011, p. 77-110Chapter in book (Refereed)
    Abstract [en]

    The research presented in this chapter contributes to knowledge about the combustion-based formation of dioxins and dioxin-like compounds. Dioxins are among the most toxic substances known to man, and are formed as by-products of industrial processes, including waste incineration. Although the emissions of dioxins from waste incineration facilities have been greatly reduced by the improved efficiency of pollution abatement technologies, the materials that remain (ashes and filters) are highly contaminated and are thus classified as hazardous waste. The principal objective of this research was to elucidate the pathways by which dioxins and dioxin-like compounds are formed in flue gas in the post-combustion zone of a laboratory-scale reactor during well-controlled combustion of waste. The potential benefits of this improved understanding include the detoxification of waste incineration residues and further reduction of harmful emissions to air, which could reduce or even eliminate the need for costly and potentially hazardous treatment.

    Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) were formed rapidly in the post-combustion zone of the laboratory-scale reactor, mainly as the temperature declined from 650°C to 400°C, with a high dependency on sufficient residence time within a specific temperature interval. Prolonged residence at temperatures above 450°C led to a reduction in the concentrations of PCDDs formed. The isomer distribution patterns of the PCDDs, PCDFs and polychlorinated naphthalenes (PCNs) in the flue gas indicated that the formation of PCDDs was largely influenced by condensation of chlorophenols and, to a lower extent, by chlorination reactions. The abundance of 1,9-substituted PCDFs was low, suggesting that chlorine substitution reactions were not favoured at positions adjacent to the oxygen bridges.The effects of injection of aromatic compounds into the flue gas were compound-dependent. Injection of naphthalene caused an increase in the formation of monochlorinated naphthalene but not in other chloronaphthalene homologues, probably because of insufficient residence time at temperatures conducive to further chlorination. Injection of dibenzo-p-dioxin appeared to result in its decomposition, chlorination and re-condensation to form PCDDs and PCDFs, whereas the introduction of dibenzofuran and fluorene led to a reduction in the concentrations of PCDDs in the flue gas. 

  • 26.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Chemistry.
    Thermal formation and chlorination of dioxins and dioxin-like compounds2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis contributes to an increased understanding of the formation of dioxins and dioxin-like compounds in combustion processes. Although emissions to air from waste incineration facilities have been greatly reduced by the use of efficient air pollution control measures, the resulting residues (ashes and filters) are highly toxic and are classified as hazardous waste. The main objective of the work underlying this thesis was to elucidate the formation and chlorination pathways of dioxins and dioxin-like compounds in waste combustion flue gases in the temperature range 640-200°C in a representative, well-controlled laboratory-scale reactor using artificial municipal solid waste. This could contribute to the reduction of harmful emissions to air and also reduce the toxicity of waste incineration residues, thus reducing or even eliminating the need for costly and potentially hazardous after-treatment.

    A comparison of four different quenching profiles showed that the formation of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) was rapid and mainly occurred in the 640-400°C temperature region, with high dependency on sufficient residence time within a specific temperature region. Prolonged residence time at high temperatures (450/460°C) reduced the PCDD yields, even at lower temperatures along the post-combustion zone. PCDD, PCDF and PCN (polychlorinated naphthalene) isomer distribution patterns indicated contributions from chlorophenol condensation as well as chlorination reactions for all three classes of compounds. The formation of PCDDs was largely influenced by chlorophenol condensation and to some extent by chlorination reactions. For the PCDFs, chlorine substitution adjacent to the oxygen bridges was unfavoured, as demonstrated by the notably lower abundance of 1,9-substituted congeners. This was supported by bidirectional orthogonal partial least squares (O2PLS) modelling. The variable with the greatest influence on the distribution of PCDD congeners was the relative free energy (RΔGf). The O2PLS models displayed distinct clusters, dividing most of the homologues into two or three sub-groups of congeners which seemed to correspond to the probability of origination from chlorophenol condensation.

    The effects of injection of aromatic structures into the flue gas differed for each class of compounds. Injection of naphthalene increased the formation of monochlorinated naphthalene but the remaining homologues appeared to be unaffected. This was probably due to insufficient residence time at temperatures necessary for further chlorination. Injected dibenzo-p-dioxin was decomposed, chlorinated and re-condensated into PCDDs and PCDFs, whereas injection of dibenzofuran and fluorene reduced the PCDD levels in the flue gas.

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  • 27.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Patrik L
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Relationships between congener distribution patterns of PCDDs, PCDFs, PCNs, PCBs, PCBzs and PCPhs formed during flue gas cooling2012In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 416, p. 269-275Article in journal (Refereed)
    Abstract [en]

    The congener patterns of mono- to octa-chlorinated dibenzo-p-dioxins (PC(1-8)DD), dibenzofurans (PC(1-8)DF), naphthalenes (PC(1-8)N), mono- to deca-chlorinated biphenyls (PC(1-10)B), di- to hexa-chlorinated benzenes (PC(2-6)Bz) and mono- to penta-chlorinated phenols (PC(1-5)Ph) in flue gas samples collected simultaneously at 450°C, 300°C and 200°C in the post-combustion zone during waste incineration in a laboratory-scale reactor in a previous study, were in this study evaluated using principal component analysis (PCA). To our knowledge this is the most comprehensive chemical and multivariate analysis to date of the thermal formation of dioxins. The PCA indicated that different formation pathways occur in the temperature regions 450-300°C and 300-200°C, and reflected a chlorination effect of PCDF and PCDD between 450°C and 200°C which could not be discerned or was less pronounced for the other compound groups. Toxic equivalents (TEQs) of PCDDs, PCDFs and PCBs, as well as total TEQ values (TEQ(Total)) were also calculated, and correlations between changes in levels of specific congeners and the TEQs were explored in the PCA. Levels of four HxCDF congeners and 1,2,3,4,8-, 1,2,3,7,8-PeCDF and 2,3,4,7,8-PeCDF showed the strongest correlations with TEQ(Total) (R(2)≥0.9). In addition, levels of 1,2,4-TriCBz correlated strongly with TEQ(Total) (R(2)>0.7), supporting previous reports that it may be a potential indicator of the TEQ.

  • 28.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Antti, Henrik
    Umeå University, Faculty of Science and Technology, Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Chemistry.
    Correlations of PCDD/F isomer distribution patterns from MSW combustion with physicochemical variables and chlorine substitution descriptorsManuscript (preprint) (Other (popular science, discussion, etc.))
  • 29.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Antti, Henrik
    Umeå University, Faculty of Science and Technology, Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Chemistry.
    Multivariate Relationships between Molecular Descriptors and Isomer Distribution Patterns of PCDD/Fs Formed during MSW Combustion2009In: Environmental Science & Technology, Vol. 43, no 18, p. 7032-8Article in journal (Refereed)
    Abstract [en]

    The isomer distribution patterns of mono- to hepta-chlorinated dibenzo-p-dioxins (PC1−7DD) and dibenzofurans (PC1−7DF) in postcombustion zone flue gas during incineration of an artificial municipal solid waste in a laboratory-scale fluidized-bed reactor were evaluated. Bidirectional orthogonal projections to latent structures (O2PLS) was used to correlate a set of physicochemical properties and chlorine substitution descriptors with the objective to identify parameters correlated with postcombustion zone PCDD and PCDF formation. The most influential variable for the distribution of PCDD congeners was chlorine substitution in positions 1 and 3 (Cl1 + 3), and overall the chlorine substitution descriptors exerted a larger impact on PCDDs than on PCDFs. For the PCDF, chlorination of the 9-position was the most influential X-variable. Distinct clustering was observed and was most pronounced for PCDFs, dividing most of the homologues into two or three subgroups of congeners. These subgroups seemed to correspond to the probability of formation by chlorophenol condensation. The sterically crowded dibenzofuran bay-sites (1- and 9-positions) were found to negatively influence PCDF formation, with chlorination of the 9-position having the greatest impact. Since PCDD/F toxicity is related to the lateral positions, elucidating the factors governing chlorination may be of great importance for detoxification of incineration byproducts.

  • 30.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Aurell, Johanna
    Umeå University, Faculty of Science and Technology, Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Formation of Non-to Octachlorinated PCDD/F During MSW Combustion in a Laboratory-Scale Fluidized-Bed Reactor2006In: Organohalogen Compounds, Vol. 68, p. 165-8Article in journal (Refereed)
  • 31.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formation and chlorination of polychlorinated naphthalenes (PCNs) in the post-combustion zone during MSW combustion2008In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 72, no 8, p. 1138-1144Article in journal (Refereed)
    Abstract [en]

    Non- to octa-chlorinated naphthalenes (PCNs) were analyzed in flue gas samples collected simultaneously at three different temperatures (450 °C, 300 °C and 200 °C, respectively) in the post-combustion zone during waste combustion experiments using a laboratory-scale fluidized-bed reactor. PCN homologue profiles in all samples were dominated by the lower chlorinated homologues (mono- to triCN), with successive reductions in abundance with each additional degree of chlorination. The isomer distribution patterns reflected ortho-directionality behavior of the first chlorine substituent, and the β-positions, i.e. the 2,3,6,7-substitution sites, seemed to be favored for chlorination. Injection of naphthalene into the post-combustion zone resulted in increased PCN levels at 200 °C, demonstrating the occurrence of chlorination reactions in the post-combustion zone. However, the increases were restricted to the least-chlorinated homologue (monoCN), probably because there was insufficient residence time for further chlorination. In addition, an episode of poor combustion (manifested by high CO levels) was accompanied by extensive formation of 1,8-diCN, 1,2,3- and 1,2,8-triCN; congeners with substitution patterns that are not thermodynamically favorable. These are believed to be products of PAH breakdown reactions and/or chlorophenol condensation. Overall, PCN formation is likely to occur via more than one pathway, including chlorination of naphthalene that is already present, de novo synthesis from PAHs and, possibly, chlorophenol condensation.

  • 32.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Swedish University of Agricultural Sciences, Unit of Biomass Technology and Chemistry, SE-901 83 Umeå, Sweden.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Effect of injection of di- and tricyclic aromatic compounds on post-combustion formation of polychlorinated dibenzo-p-dioxins and dibenzofurans2011In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 409, no 18, p. 3386-3393Article in journal (Refereed)
    Abstract [en]

    The formation of mono- to octachlorinated dibenzo-p-dioxins (PC(1-8)DD) and dibenzofurans (PC(1-8)DF) was studied using a model waste in a laboratory-scale combustion reactor with simultaneous collection of flue gas at three different temperatures (450°C, 300°C, and 200°C) in the post-combustion zone. To investigate the influence of chlorination reactions and the effects of carbon backbone-containing compounds present in the flue gases, five aromatic compounds were injected into the flue gas, namely dibenzofuran (DF), biphenyl (BP), naphthalene, phenanthrene and fluorene. The injection of DF induced a reduction in the concentration of PC(3-5)DD, but did not significantly influence the concentration of PCDF. A reduction in the concentration of PC(3-5)DD was also observed during the injection of fluorene, which is structurally very similar to DF. The injection of biphenyl, naphthalene and phenanthrene had less pronounced effects on the formation of PCDD and PCDF. A possible explanation of the observed changes during injection of DF and fluorene, based on homologue profiles and affected congeners, involves formation of radical species from fluorene and/or dibenzofuran. The fluorene radical is stabilized by the delocalization of electrons across the aromatic ring structure and has the propensity to react with highly abundant hydrogen chloride, whereas the molecular species would require reaction with Cl(2) or chlorine radicals.

  • 33.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Post-combustion formation of PCDD, PCDF, PCBz, and PCPh in a laboratory-scale reactor: Influence of dibenzo-p-dioxin injection2009In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 76, no 6, p. 818-25Article in journal (Refereed)
    Abstract [en]

    Formation of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF), benzenes (PCBz), and phenols (PCPh) was studied during combustion of an artificial municipal solid waste (MSW) in a laboratory-scale fluidized-bed reactor with simultaneous collection of flue gas samples at three different temperatures in the post-combustion zone (450 degrees C, 300 degrees C, and 200 degrees C). PCDF, PCBz, and PCPh were predominantly formed at or above the first sampling point (450 degrees C) with a dominance of the lower chlorinated homologues. PCDDs, on the other hand, were dominated by the intermediately chlorinated homologues with concentrations peaking at 300 degrees C. The dominating PCPh congeners clearly displayed the ortho-para directionality, which is indicative of electrophilic aromatic substitution, as did the PCBz isomer distribution patterns to some extent. Comparison of the observed PCBz isomer distribution patterns to prior work may indicate coupling of aliphatic species in chlorobenzene formation. The PCDDs seemed to be largely influenced by chlorophenol condensation reactions and to some extent chlorination reactions, while the PCDFs displayed a chlorination-oriented pattern for the mono- to tri-chlorinated homologues and a PCPh condensation pattern for the higher chlorinated homologues. Injection of non-chlorinated dibenzo-p-dioxin at 650 degrees C resulted in increased formation of Tri-HxCDD and a decrease in the dibenzofuran levels. The affected PCDD and PCDF congeners were not products expected to form from chlorine substitution, but instead are well known chlorophenol condensation products.

  • 34.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Grabic, Roman
    Multivariate relationships between molecular descriptors and isomer distribution patterns of PCBs formed during household waste incineration2014In: Environmental Science and Pollution Research, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 21, no 4, p. 3082-3090Article in journal (Refereed)
    Abstract [en]

    The congener-specific concentrations of mono- to deca-chlorinated biphenyls (PC1-10B) in post-combustion zone flue gases from a laboratory-scale fluidized bed reactor were evaluated and correlated with a set of physicochemical properties and chlorine substitution descriptors. The objective was to identify parameters that affect post-combustion zone polychlorinated biphenyl (PCB) formation and interpreting observed correlations by using principal component analysis (PCA), and bidirectional orthogonal projections to latent structures (O2PLS). Both physicochemical variables and chlorine substitution descriptors were shown to have significant effects on the PCB congener distribution; however, the physicochemical descriptors were more influential in all-homologue models, whereas the chlorine substitution descriptors had a greater impact in single-homologue models, which suggests that PCB formation in general may be under thermodynamic control, whereas the distribution of isomers within homologues is more sensitive to chlorine substitution parameters. The EHOMO and ELUMO variables notably influenced both the PCA and the O2PLS models, which indicate that reactivity and polarization in the molecular structures of the PCBs is of importance.

  • 35.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundin, Lisa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Grabic, Roman
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Characterisation and fingerprinting of PCBs in flue gas and ash from waste incineration and in technical mixtures2011In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 85, no 3, p. 509-515Article in journal (Refereed)
    Abstract [en]

    Congener patterns of mono- to deca-chlorinated biphenyls (PC(1-10)B) were evaluated in (a) waste incineration flue gases collected in the post-combustion zone of a laboratory-scale fluidized-bed reactor, (b) ashes from two different MSW incineration plants, and (c) published data of eight Aroclor formulations. The congener patterns of the flue gases, ashes, and Aroclor mixtures clearly differed from each other, likely reflecting differences in formation pathways. The flue gas congener patterns were largely dominated by the least chlorinated congeners, whereas the ashes displayed more evenly distributed patterns. The most abundant congeners indicated a preference for 3,3',4,4'-oriented substitution, which may be related to de novo-type formation involving perylene. Principal component analysis confirmed that congener patterns differed among the three matrices and also distinguished flue gases collected at 200°C from those collected at 300°C and 450°C. This distinction could be partly explained by the degree of chlorination, although the substitution status of the ortho-position, and substitution in the 3,3',4,4'-positions also seemed to be influential. Injecting biphenyl into the post-combustion zone of the reactor did not alter the patterns, indicating that availability of the backbone structure is not a limiting factor for PCB formation.

  • 36.
    Jansson, Stina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Söderström, Hanna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Patrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nording, Malin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Implementation of Problem-Based Learning in Environmental Chemistry2015In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 92, no 12, p. 2080-2086Article in journal (Refereed)
    Abstract [en]

    Environmental Chemistry covers a range of topics within the discipline of chemistry, from toxicology to legislation, which warrants interdisciplinary study. Consequently, problem-based learning (PBL), a style of student-centered learning which facilitates the integration of multiple subjects, was investigated to determine if it would be a more appropriate instructional method for teaching Environmental Chemistry than the traditional teacher-centered education model. This article describes the practical aspects of course development and implementation of PBL in a master’s level course in Environmental Chemistry. Overall, the results, which were collected from the initial two years of the course, indicated that the students were pleased and found PBL to be an efficient methodology for not only learning, but also acquiring an in-depth understanding of Environmental Chemistry. This is intended as a case-study with the target audience consisting primarily of high school and undergraduate chemistry teachers, but may also be useful for teachers in other subject areas with an interest in student-centered education.

  • 37. Josefsson, Sarah
    et al.
    Bergknut, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Futter, Martyn N.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Laudon, Hjalmar
    Lundin, Lisa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wiberg, Karin
    Persistent Organic Pollutants in Streamwater: Influence of Hydrological Conditions and Landscape Type2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 14, p. 7416-7424Article in journal (Refereed)
    Abstract [en]

    Concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and hexachlorobenzene (HCB) in streamwater were measured in a remote catchment in northern Sweden and downstream to the Baltic Sea. Sampling took place at seven sites during two years and under different hydrological conditions: during the snow-free, snow-covered, and spring-flood seasons. Concentrations varied substantially between seasons and were up to 20 times higher during the spring flood compared to the preceding snow-covered period. The increase in concentrations with runoff was due to higher levels of particle-associated contaminants, while the dissolved concentrations remained stable. Particulate-contaminant concentrations were positively correlated primarily to suspended particulate matter (SPM) at sites in areas with a high land-cover fraction of sorted sediment. When upstream sampling locations were compared, a mire-dominated stream had higher concentrations and a lower retention of atmospherically deposited contaminants than a forest stream of the same catchment size. Contaminant concentrations (normalized to volume) did not increase consistently downstream despite the presence of several point sources. However, when normalized to the amount of SPM, concentrations were on average >20 times higher at the outlet in the Baltic Sea compared to the outlet from the remote catchment without point sources.

  • 38. Khaled, Amina
    et al.
    Richard, Claire
    Redin, Lisa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Niinipuu, Mirva
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Janson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jaber, Farouk
    Sleiman, Mohamad
    Characterization and Photodegradation of Polybrominated Diphenyl Ethers in Car Seat Fabrics from End-of-Life Vehicles2018In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, no 3, p. 1216-1224Article in journal (Refereed)
    Abstract [en]

    In this study, we examined the photodegradation of decabromodiphenyl ether (BDE-209) on the surface of car seat covers from end-of-life vehicles (ELVs). Samples were collected at two car dismantling facilities in Sweden and cover car models from 1989 to 1998. The content of polybrominated diphenyl ethers (PBDEs) in nine real samples (fabric and polyurethane foam) was first characterized. Fabric samples that did not contain BDE-209 were then spiked with BDE-209 and irradiated in the laboratory and under sunlight. Photoproducts were identified using high performance liquid chromatography coupled to electrospray ionization mass spectrometer (HPLC-ESI-Orbitrap-MS), whereas volatile products were analyzed by gas chromatography mass spectrometry (GC-MS). Similar photodegradation rates and oxidation products were observed in fabric samples irradiated in the laboratory and those collected from ELVs. Estimated half-life of BDE-209 on fabric inside vehicles ranged from 3 to 6 years. Thirteen major photoproducts were identified as lower brominated products, hydroxylated BDEs, brominated and hydroxylated dibenzofurans (PBDFs) and dioxins (PBDDs). Furthermore, several photoproducts were found to be transferable into water, particularly bromophenols and hydroxylated BDEs, and others into gas phase, such as bromomethanol and 1,2-dibromoethane. This should be taken into consideration for better estimating exposure to PBDEs and to develop strategies for ELV recycling.

  • 39.
    Kozyatnyk, Ivan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Benavente, Veronica
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weidemann, Eva
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gentili, Francesco G.
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Influence of hydrothermal carbonization conditions on the porosity, functionality, and sorption properties of microalgae hydrochars2023In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, no 1, article id 8562Article in journal (Refereed)
    Abstract [en]

    Green microalgae is a possible feedstock for the production of biofuels, chemicals, food/feed, and medical products. Large-scale microalgae production requires large quantities of water and nutrients, directing the attention to wastewater as a cultivation medium. Wastewater-cultivated microalgae could via wet thermochemical conversion be valorised into products for e.g., water treatment. In this study, hydrothermal carbonization was used to process microalgae polycultures grown in municipal wastewater. The objective was to perform a systematic examination of how carbonization temperature, residence time, and initial pH affected solid yield, composition, and properties. Carbonization temperature, time and initial pH all had statistically significant effects on hydrochar properties, with temperature having the most pronounced effect; the surface area increased from 8.5 to 43.6 m2 g−1 as temperature was increased from 180 to 260 °C. However, hydrochars produced at low temperature and initially neutral pH generally had the highest capacity for methylene blue adsorption. DRIFTS analysis of the hydrochar revealed that the pH conditions changed the functional group composition, implying that adsorption was electrostatic interactions driven. This study concludes that un-activated hydrochars from wastewater grown microalgae produced at relatively low hydrothermal carbonization temperatures adsorb methylene blue, despite having low surface area.

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  • 40.
    Kozyatnyk, Ivan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Latham, Kenneth G.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Valorization of Humic Acids by Hydrothermal Conversion into Carbonaceous Materials: Physical and Functional Properties2019In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 7, no 2, p. 2585-2592Article in journal (Refereed)
    Abstract [en]

    Humic acids (HAs) represent an economic and environmental challenge in water treatment, as they have the propensity to foul membranes and create toxic byproducts when interacting with chlorine. To overcome this, HAs were submitted to hydrothermal carbonization to convert them into an easy to remove, valuable carbon material. The result was a carbonaceous material which was easy to filter/dewater compared to HAs with a char yield of 49 +/- 1.8 wt %, and with 46.6 1.4 wt % ending up in the water phase, 2.2 +/- 0.2 wt % in the tar, and the rest in the gaseous fraction. The molecular weight distribution of the organic matter in the water pre-and post-HTC indicated that the structure was broken into several different fragments with a lower molecular weight than that initially present. Physicochemical analysis of the material via elemental analysis, X-ray photoelectron spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, and solid-state nuclear magnetic resonance indicated that under hydrothermal carbonization, the aromatic structure of HAs condensed. Carboxylic acids groups were also lost from the surface of HAs, with ether and alcohols increasing because of their loss. The morphology of the obtained material had an amorphous macrostructure consisting of many smaller light lamellar carbon fragments. Finally, the hydrothermal treatment increased the surface area from 0.4 to 103.0 m(2) g(-1).The porosity is located in the mesoporous range of 10-80 nm with a maximum peak at 50 nm.

  • 41.
    Kozyatnyk, Ivan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Oesterle, Pierre
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wurzer, Christian
    UK Biochar Research Centre, School of GeoSciences, University of Edinburgh, UK, Edinburgh, United Kingdom.
    Mašek, Ondřej
    UK Biochar Research Centre, School of GeoSciences, University of Edinburgh, UK, Edinburgh, United Kingdom.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Removal of contaminants of emerging concern from multicomponent systems using carbon dioxide activated biochar from lignocellulosic feedstocks2021In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 340, article id 125561Article in journal (Refereed)
    Abstract [en]

    Adsorption of six contaminants of emerging concern (CECs) – caffeine, chloramphenicol, carbamazepine, bisphenol A, diclofenac, and triclosan – from a multicomponent solution was studied using activated biochars obtained from three lignocellulosic feedstocks: wheat straw, softwood, and peach stones. Structural parameters related to the porosity and ash content of activated biochar and the hydrophobic properties of the CECs were found to influence the adsorption efficiency. For straw and softwood biochar, activation resulted in a more developed mesoporosity, whereas activation of peach stone biochar increased only the microporosity. The most hydrophilic CECs studied, caffeine and chloramphenicol, displayed the highest adsorption (22.8 and 11.3 mg g−1) onto activated wheat straw biochar which had the highest ash content of the studied adsorbents (20 wt%). Adsorption of bisphenol A and triclosan, both relatively hydrophobic substances, was highest (31.6 and 30.2 mg g−1) onto activated biochar from softwood, which displayed a well-developed mesoporosity and low ash content.

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  • 42.
    Kozyatnyk, Ivan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Yacout, Dalia M. M.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Van Caneghem, Jo
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparative environmental assessment of end-of-life carbonaceous water treatment adsorbents2020In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 302, article id 122866Article in journal (Refereed)
    Abstract [en]

    This study evaluates and compares the environmental impacts arising from the disposal of different carbonaceous sorbents used for wastewater treatment. Three different adsorption materials were considered, i.e. activated carbon, biochar and hydrochar, and three end-of-life management approaches, i.e. incineration, regeneration and landfilling. The highest overall environmental impact was of Carcinogenic effects and Freshwater Ecotoxicity due to emissions of heavy metals during production of all types of sorbents. The use of materials with higher adsorption capacities and regeneration of carbonaceous materials were considered and shown to be an efficient way for reducing the overall environmental impacts of the different adsorbents. The compensation of fossil fuel incineration by using recovered heat led to negative impacts in all categories. Recirculation of HTC process water reduced the impact on Freshwater Ecotoxicity and Eutrophication.

  • 43.
    Latham, Kenneth G.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Discipline of Chemistry, University of Newcastle, NSW, Callaghan, Australia.
    Kozyatnyk, Ivan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Figueira, Joao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Carlborg, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Rosenbaum, Erik
    MTC-Miljötekniskt Center AB, Dåva Energiväg 8, Umeå, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Self-generation of low ash carbon microspheres from the hydrothermal supernatant of anaerobic digestate: Formation insights and supercapacitor performance2021In: Chemical Engineering Journal Advances, E-ISSN 2666-8211, Vol. 6, article id 100097Article in journal (Refereed)
    Abstract [en]

    This work provides the first observations of and insights into the self-generation of carbon microspheres from the supernatant after hydrothermal carbonization of anaerobic digestate has been completed and the hydrochar removed. Solid State NMR and XPS revealed that the carbon microspheres were comprised of decomposed fragments of proteins, carbohydrates and lignin. The carbon microspheres were significantly lower in ash content (3.1%), compared to the hydrothermal solid (41.2%) and precursor (25.2%) and their formation reduced the total organic carbon load of the supernatant. The low ash content allowed them to be easily activated, achieving a surface area of 1711.0 m2 g−1, compared to 51.4 m2 g−1 for the activated hydrothermal solid and 12.8 m2 g−1 for the activated precursor. The microcarbon spheres achieved a specific capacitance from cyclic voltammetry of 86 F g−1 at 100 mV s−1 to 176 F g−1 at 1 mV s−1, while the gravimetric capacitance was 42 F g−1 at 25 A g−1 and 140 F g−1 at 0.5 A g−1 in 0.5 M Li2SO4 and a 1.8V potential window. Overall, this study highlights the importance of exploring this new product and its valorisation potential for the hydrothermal carbonization of ash-rich precursors.

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  • 44.
    Latham, Kenneth G.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Discipline of Chemistry, University of Newcastle, NSW, Callaghan, Australia.
    Matsakas, Leonidas
    Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
    Figueira, Joao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kozyatnyk, Ivan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Occupational and Environmental Medicine Center, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
    Rova, Ulrika
    Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
    Christakopoulos, Paul
    Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Impact of temperature and residence time on the hydrothermal carbonization of organosolv lignin2022In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 166, article id 105623Article in journal (Refereed)
    Abstract [en]

    Herein, we have investigated how pure lignin extracted from birch and spruce via a hybrid organosolv/steam explosion method reacts under hydrothermal carbonization (HTC) to produce hydrochar, a product that has found applications in environmental remediation, energy storage and catalysis. We subjected thirteen lignin samples obtained from birch and spruce under different extraction conditions to HTC at 260 ℃ for four hours. The yield of hydrochar varied between the different extraction conditions and source, although no clear correlation between extraction conditions and yield could be observed. For instance, lignin from birch pretreated in 60%v/v ethanol for 15 min resulted in a hydrochar yield of 39 wt%. Increasing the time to 30 and 60 resulted in a hydrochar yield of 27 wt% and 23 wt%, respectively. This suggested that small changes in the organosolv reaction conditions might produce highly structurally different lignin, resulting in the difference in HTC yield. Thus, we chose a subset of four lignin samples to investigate in-depth, subjecting these samples to a range of hydrothermal reaction temperatures and residence times. Solid State NMR and FTIR analysis indicated that the most significant structural changes occurred below 230 ℃ resulting in the breaking of C-O- linkages. Increasing the temperature or time had minimal impact, with no further C-O- linkages broken and no changes to the ring structure of C-C groups. Size exclusion chromatography indicated that the degree of micro and macromolecules in the liquid product varied significantly with lignin source and HTC reaction conditions. Overall, this study demonstrated that lignin has a large reaction range where it produces a very chemically similar solid product, with the only major difference being the yield of material. This is important for industry, as it indicates that a similar solid product can be easily achieved independently of extraction conditions allowing the HTC reaction to be tuned towards extracting the maximum benefit from products contained in the liquid.

  • 45.
    Latham, Kenneth G.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Discipline of Chemistry, University of Newcastle, Callaghan, NSW, Australia.
    Matsakas, Leonidas
    Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
    Figueira, João
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rova, Ulrika
    Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
    Christakopoulos, Paul
    Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Examination of how variations in lignin properties from Kraft and organosolv extraction influence the physicochemical characteristics of hydrothermal carbon2021In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 155, article id 105095Article in journal (Refereed)
    Abstract [en]

    Seven different lignin samples, three from Kraft extraction and four from organosolv extraction, were subjected to hydrothermal treatment at 260℃ for four hours to assess the impact of lignin type on the physicochemical properties of the hydrothermal material. The 13C Solid state NMR, XPS, FTIR and SEM analysis revealed that the different sources of lignin and the extraction conditions created variations in the degree of syringyl and guaiacyl subunits, inter-unit bonding arrangements, morphology and surface composition. Hydrothermal carbonization appeared to “normalize” the differences between each of the lignin samples, via breaking β-O-4 or α-O-4 linkages, removal of methoxy and syringyl subunits, and creation of C–C and 4-O-5 linkages to polymerization into large 100−200 μm amorphous carbon particles. Overall, this study indicates that the source and extraction type have minimal influence on the physicochemical structure and morphology of the final hydrothermal product.

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  • 46.
    Lundin, Lisa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gomez-Rico, Maria Francisca
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Forsberg, Christer
    Vattenfall AB Heat, Älvkarlebylaboratoriet, S-814 26 Älvkarleby, Sweden.
    Nordenskjöld, Carl
    Vattenfall AB Heat, Älvkarlebylaboratoriet, S-814 26 Älvkarleby, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Vattenfall AB Heat, Älvkarlebylaboratoriet, S-814 26 Älvkarleby, Sweden.
    Reduction of PCDD, PCDF and PCB during co-combustion of biomass with waste products from pulp and paper industry2013In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 91, no 6, p. 797-801Article in journal (Refereed)
    Abstract [en]

    The use of waste wood as an energy carrier has increased during the last decade. However, elevated levels of alkali metals and chlorine in waste wood compared to virgin biomass can cause increased deposit formation and higher concentrations of organic pollutants. In this study, we investigated the effect of the ChlorOut technique on concentrations of organic pollutants. Ammonium sulfate was injected into the combustion system to inhibit formation of KCl (which causes deposits) and persistent organic pollutants, namely polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs). The results showed that concentrations of the toxic congeners of PCDD, PCDF and PCB decreased in the presence of ammonium sulfate.

  • 47.
    Lundin, Lisa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A desktop study on destruction of persistent organic compounds in combustion systems2017Report (Other academic)
    Abstract [en]

    On behalf of the Swedish Environmental Protection Agency, Dr. Lisa Lundin and Dr. Stina Jansson at the Department of Chemistry, Umeå University, has conducted this desktop study. The main aim of this desktop study was to provide a compilation of the current state of knowledge of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF), polybrominated diphenylethers (PBDE), hexabromocyclodecane (HBCD), and perfluoroctanesulphonate (PFOS) with regard to their degradation efficiency in advanced solid waste incinerators (ASWI). The objective was also to assess if more support is needed to determinethe degradation efficiency of these compounds in ASWIs.

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  • 48.
    Lundin, Lisa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The effects of fuel composition and ammonium sulfate addition on PCDD, PCDF, PCN and PCB concentrations during the combustion of biomass and paper production residuals2014In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 94, p. 20-26Article in journal (Refereed)
    Abstract [en]

    The use of waste wood as an energy carrier has increased during the last decade. However, the higher levels of alkali metals and chlorine in waste wood compared to virgin biomass can promote the formation of deposits and organic pollutants. Here, the effect of fuel composition and the inhibitory effects of ammonium sulfate, (NH4)2SO4, on the concentrations of persistent organic pollutants (POPs) in the flue gas of a lab-scale combustor was investigated. Ammonium sulfate is often used as a corrosion-preventing additive and may also inhibit formation of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). In addition to PCDDs and PCDFs, polychlorinated naphthalenes (PCN) and biphenyls (PCB) were also analyzed. It was found that the flue gas composition changed dramatically when (NH4)2SO4 was added: CO, SO2, and NH3 levels increased, while those of HCl decreased to almost zero. However, the additive's effects on POP formation were less pronounced. When (NH4)2SO4 was added to give an S:Cl ratio of 3, only the PCDF concentration was reduced, indicating that this ratio was not sufficient to achieve a general reduction in POP emissions. Conversely, at an S:Cl ratio of 6, significant reductions in the WHO-TEQ value and the PCDD and PCDF contents of the flue gas were observed. The effect on the PCDF concentration was especially pronounced. PCN formation seemed to be promoted by the elevated CO concentrations caused by adding (NH4)2SO4.

  • 49. Matsakas, Leonidas
    et al.
    Gao, Qiuju
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rova, Ulrika
    Christakopoulos, Paul
    Green conversion of municipal solid wastes into fuels and chemicals2017In: Electronic Journal of Biotechnology, E-ISSN 0717-3458, Vol. 26, article id 4Article, review/survey (Refereed)
    Abstract [en]

    Presently, the society is facing a serious challenge for the effective management of the increasing amount of produced municipal solid wastes. The accumulated waste has caused a series of environmental problems such as uncontrolled release of greenhouse gases. Moreover, the increasing amount of wastes has resulted in a shortage of areas available for waste disposal, resulting in a nonsustainable waste management. These problems led to serious public concerns, which in turn resulted in political actions aiming to reduce the amount of wastes reaching the environment. These actions aim to promote sustainable waste management solutions. The main objective of these policies is to promote the recycling of municipal solid waste and the conversion of waste to energy and valuable chemicals. These conversions can be performed using either biological (e.g., anaerobic digestion) or thermochemical processes (e.g., pyrolysis). Research efforts during the last years have been fruitful, and many publications demonstrated the effective conversation of municipal solid waste to energy and chemicals. These processes are discussed in the current review article together with the change of the waste policy that was implemented in the EU during the last years. 

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  • 50. Matsakas, Leonidas
    et al.
    Sarkar, Omprakash
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rova, Ulrika
    Christakopoulos, Paul
    A novel hybrid organosolv-steam explosion pretreatment and fractionation method delivers solids with superior thermophilic digestibility to methane2020In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 316, article id 123973Article in journal (Refereed)
    Abstract [en]

    Rising environmental concerns and the imminent depletion of fossil resources have sparked a strong interest towards the production of renewable energy such as biomethane. Inclusion of alternative feedstock’s such as lignocellulosic biomass could further expand the production of biomethane. The present study evaluated the potential of a novel hybrid organosolv-steam explosion fractionation for delivering highly digestible pretreated solids from birch and spruce woodchips. The highest methane production yield was 176.5 mLCH4 gVS−1 for spruce and 327.2 mL CH4 gVS−1 for birch. High methane production rates of 1.0–6.3 mL min−1 (spruce) and 6.0–35.5 mL min−1 (birch) were obtained, leading to a rapid digestion, with 92% of total methane from spruce being generated in 80 h and 95% of that from birch in 120 h. These results demonstrate the elevated potential of the novel method to fractionate spruce and birch biomass and deliver cellulose-rich pretreated solids with superior digestibility.

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