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  • 101.
    Botelho, Anneliese H.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. CNPq - Brazil.
    Zhang, Ping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effects of parallel fractures near a free surface on velocity amplification of S-wave2017In: Proceedings of the Ninth International Symposium on Rockbursts and Seismicity in Mines / [ed] Javier Vallejos, Santiago do Chile: University of Chile , 2017, , p. 337Conference paper (Refereed)
    Abstract [en]

    When rock support is designed in a seismically active underground mine, it is important tochoose the right ejection velocity and calculate corresponding kinetic energy. Field monitoringand back-analyses have shown that ejection velocity of the order of 10 m/s and higher can resultfrom seismic events of moderate magnitude. Such velocities are much higher than those predictedusing peak particle velocity (PPV) obtained from scaling laws. Many researches have reportedthe amplification of particle velocity near excavation surface. Velocity amplification of P-wavetravelling through fractured rock near a free surface was recently studied. The amplification ofseismic waves on the skin of excavation is of interest in case of large seismic events. Seismic eventswith large magnitude are often associated with slip along weaknesses or shear fracturing of intactrock, which according to observations radiate much stronger S-wave as compared to P-wave.In this paper, velocity amplification of S-wave was investigated by modelling the dynamicinteraction between fractured rock and a free surface using a 2D discontinuum-based numericalprogram, UDEC (Universal Distinct Element Code). A 1D model with a fractured zone wasused to represent the fractured rock in this investigation. It is found that the shear stress ratio,wave frequency, fracture stifness, fracture spacing and thickness of fractured zone afect thevelocity amplification, in which the shear stress ratio is the most crucial factor influencing wavetransmission. The results have proved that the interaction of the seismic wave and multiplefractures near the free surface strongly influences the ground motion.

  • 102.
    Brundin, Herman
    et al.
    SÖRAB.
    Kihl, Anders
    Rang-Sells Avfallsbehandling AB.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Rihm, Thomas
    RVF service AB.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tham, Gustav
    Telge Återvinning AB.
    Långtidsegenskaper hos tätskikt innehållande bentonit2001Report (Other academic)
    Abstract [sv]

    Bentonit är en starkt vattenupptagande och svällande naturlig lera med låg vattengenomsläpplighet. Huvudkomponenten är mineralet montmorillonit, som tillhör gruppen smektiter och som ger bentoniten dess unika egenskaper. Syftet med uppdraget är att söka identifiera vilka mekanismer och faktorer som kan vara begränsande för funktionen på kort och lång sikt hos tätskikt innehållande bentonitmattor samt blandningar av bentonit och andra material. I rapporten ges underlag för projektering, utformning och drift av deponier med tätskikt innehållande bentonit. Där redovisas också tre fallstudier från Högbytorp, Löt och Tveta.

  • 103.
    Brännvall, Evelina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Accelerate ageing of refuse-derived-fuel (RDF) fly ashes2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ashes have properties that can be exploited in various applications, e.g. some ashes can be used in the construction of barriers in a landfill final top cover. A landfill top cover is a multilayer construction that protects the environment in several ways, for instance hindering gas emissions from the landfill body and water infiltration into the waste.Impervious natural materials like clay, synthetic materials like geomembranes or bentonite carpets, geosynthetic clay liners or combinations of such materials are commonly used in landfill top cover constructions. Since differential settlement may occur and the lifetimes of the synthetic materials are uncertain, it is advantageous to use thick mineral constructions. There is a great need for these materials, and substantial savings of resources can be made if alternative waste materials, like ashes, are used. Currently, ashes are either landfilled or used as construction materials. They are subject to weathering processes, including physical, chemical and mineralogical changes caused (inter alia) by fluctuations of temperature and humidity, atmospheric gases or acid rain. Ashes contain various potentially hazardous and non-hazardous chemical compounds. Therefore, precautions must be taken to avoid leaching of substances such as heavy metals into the surrounding environment. Mineral phases that are initially present and/or that form during the ageing are primarily responsible for the immobilization or leaching of diverse metals and salts. Newly formed mineral phases like clay minerals are of main interest, because of their very high cation exchange capacity, swelling and expansion properties.The conditions found in a landfill environment are likely to favour clay mineral formation. This thesis is based on studies on the effects of accelerated ageing on refuse-derived-fuel (RDF) fly ashes, in experiments under controlled laboratory conditions, intended to derive models to predict the stability of RDF fly ashes used in a landfill liner and the mineralogical changes that occur in them. A reduced factorial design was applied, followed by multivariate data analysis, to evaluate the effects of five factors - carbon dioxide (CO2) levels, temperature, relative air humidity (RH), time and the quality of added water - on mineral transformations within the ashes, and their acid neutralization capacity (ANC) and leaching behaviour.Minerals (ettringite and hydrocalumite) promoting the immobilization of hazardous compounds were found in both fresh ash and ash aged under atmospheric conditions, but these minerals disappeared upon carbonation. The main phases in ash at 20% and 100% CO2 were calcite, gypsum/anhydrite and vaterite. The abundance of gypsum and anhydrite was directly related to the temperature at which ashes were aged. The major mineral phases detected in ashes aged under 20% CO2, 65% RH and 30°C (corresponding to conditions generally found in a landfill cover) were calcite and gypsum/bassanite. The pH values of these ash specimens ranged from 7.2 to 7.6, indicating advanced carbonation. Ageing decreased pH values from 12.4 to 7.2, consequently affecting the leaching behaviour of most chemicals measured in the leachates. Levels of Ba, Ca, Cl, Cr, Cu, Pb, K and Na decreased over the study period while those of Mg, Zn and SO4 increased. No clay minerals were detected by XRD and SEM analysis in either fresh or aged ashes. However, geochemical modelling indicated that such minerals may precipitate. The modelling also indicated that clay minerals like saponite, vermiculite, chrysotile and hydrotalcite were likely to precipitate in most leachates from ash aged for 3, 10 and 22 months. Smectite, montmorillonite and illite may precipitate in leachates of ash aged for 31 months. The formation of smectite, montmorillonite and vermiculite would be advantageous due to their very high cation exchange capacities, which would favour the stabilization/immobilization of heavy metals in the mineral phases.

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  • 104.
    Brännvall, Evelina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Suitability of fly ash for construction and land applications2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Municipal solid waste incineration fly ash is often landfilled or sent abroad for stabilization because it is considered a hazardous waste. These approaches to fly ash are both costly, and highlight the need for alternative and sustainable ash recycling. Both the needs of waste recycling and preservation of natural resources can be solved by using fly ashes as a secondary construction material and as soil fertilizer.Three types of fly ashes have been investigated in the laboratory experiments. Namely municipal solid waste incineration (MSWI), refuse-derived-fuel (RDF) and biofuel fly ashes. Factors influencing changes in chemical properties and mineralogical composition of RDF fly ash exposed to environmental conditions close to those that are found in a landfill top cover were evaluated in the accelerated ageing experiment. Element availability to leaching and plant uptake in soil amended with MSWI, biofuel fly ashes and biosolids was also evaluated.RDF fly ash exposed to the conditions found in a landfill top cover (20% CO2, 65% RH, 30°C T) lead to the chemical and mineralogical transformations that resulted in reduced leaching of most of the elements studied here. Only concentrations of Cl- in the leachates were an issue, because they still exceeded the leaching limit values; nevertheless the leaching of this element in aged ash decreased by 50% compared to fresh ash.Application of pelletized MSWI fly ash with biosolids on soil resulted in elevated total concentrations of As, Cd and Pb in soil (by 29%, 100% and 300%), but dissolved concentrations of these elements in soil pore water, except the As, were low as in the range of drinking water concentrations (98/83/EC). Furthermore, the concentrations of Cd and Pb in plant biomass were negligible regardless of the type of ash used.Based on the observations, RDF fly ash is considered as a suitable material to be used in a landfill liner. Whereas MSWI and biofuel fly ashes based on element availability for plants studies, could be considered suitable for land applications. But doses to be applied on soil should be adjusted to the type of ashes used to avoid accumulation of potentially toxic elements in soil over time.

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  • 105. Brännvall, Evelina
    et al.
    Andreas, Lale
    Diener, Silvia
    Tham, Gustav
    Telge AB, Södertälje.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Influence of accelerated ageing on acid neutralization capacity and mineralogical transformations in refuse derived-fuel fly ashes2009In: SARDINIA 2009: Twelfth International Waste Management and Landfill Symposium ; [5 - 9 October 2009, S. Margherita di Pula, Cagliari, Sardinia, Italy] / [ed] Raffaello Cossu, Cagliari: CISA, Environmental Sanitary Engineering Centre , 2009, Vol. 1Conference paper (Refereed)
    Abstract [en]

    This study is a part of a long-term collaboration between Telge Återvinning AB at Södertälje in South Sweden and Lulea University of Technology (LTU) in the Northern part of Sweden. Ashes and other industrial wastes used for landfill cover construction have been studied for several years. However, there is a need for further investigations with regard to the long-term mechanical and chemical stability of ash liners in landfill cover constructions. Long-term changes of ashes are investigated by laboratory studies on accelerated weathering (ageing) using experimental design. With regard to weathering, several stages can be identified: hydration and carbonation are well known processes while the processes surrounding the conversion of ash to clay minerals are less well known. There are a number of studies showing that the process of mineral transformation during the ageing of coal or MSWI ashes is quite similar to that of volcanic ashes in nature. Yet, the time frames are quite different: while volcanic ashes need several thousands of years for clay mineral development, there are evidences as well that e.g. clay illite is formed from glass phases in MSWI bottom ash after only 12 y or that clay like amorphous material can be formed in micro-scale throughout the surfaces of coal ash particles after 8 y of natural weathering (Zevenbergen et al., 1999; Zevenbergen et al., 1998). There are a lot of studies performed on rapid fly ash conversion into zeolites by hydrothermal alkaline treatment, the success of which strongly depends on alkaline conditions and the silica-alumina composition of the fly ash source (Inada et al., 2005). These results provide further support to the hypothesis that the observed rapid clay like mineral formation arose as a result of the initially high pH of ash, which promotes rapid dissolution of certain components of aluminosilicate glasses. Furthermore, in a long term perspective these aluminosilicates can transform into zeolites, smectites or halloysites dependent on the solution pH and leaching rate. Based on these studies on volcanic, coal or MSWI ashes we presume that refuse derived fuel (RDF) ashes, like those that are used in the Tveta landfill cover, will be subject to analogical weathering and mineral transformation processes.In order to investigate the mineral transformation in RDF fly ashes, a designed laboratory experiment was performed. A reduced factorial experimental design for accelerated ageing has been applied to evaluate the influence of five factors: carbon dioxide (CO2), temperature, relative air humidity, time and, quality of added water (Table 1). Table 1 Factors and levels tested in the reduced multivariate factorial design for the study of accelerated ageing of RFD fly ashesFactorLowMiddleHighCarbon dioxide, CO2 (%)Atmosphere (0.038)20*100Temperature, ºC5 3060Relative air humidity, Rh (%)3065100Time, months31022Water qualityDistilled -LeachateThe influence of these factors on mineralogical composition, leaching behaviour and acid neutralization capacity (ANC) is analysed and evaluated with the aid of multivariate data analysis. The MVDA modelling was performed with SIMCA-P+ 11.5 version program developed by Umetrics AB (Eriksson and Umetrics Academy, 2006). Principle component analysis (PCA) technique was used and presented in this paper. PCA is an interdependence model where all variables are analysed simultaneously as a single set in a data matrix X. Triplicates were tested for each factor combination. Sampling was performed after 3, 10 and 22 months of accelerated ageing. Mineral composition was analysed by X-Ray Diffraction (XRD). Acid neutralisation capacity was performed at 8.3 and 4.5 pH with 0.1 M HCl solution. The experimental set-up of accelerated ageing of RDF fly ashes is showed in Fig. 1. Preliminary evaluation of the mineral transformations in aged RDF fly ashes revealed that the carbonation process was not yet completed in the some of the specimens (Fig.2). This still caused high pH (pH=12.7) in the solution even though a calcite phase was found in all aged fly ashes. Multivariate data analysis confirmed that carbon dioxide affects the pH and ANC of fly ashes during ageing of RDF fly ashes. The specimens prepared with leachate water had higher ANC than the specimens with distilled water. The ANC8.3 was most influenced by 30 ºC temperature and 65 % relative humidity (ANC8.3 = 0.05 mmol/g) and this well corresponds to the results found in the literature. The ageing time factor has the highest influence on ANC4.5. A more detailed analysis of other mineral phases including clay-like minerals in aged fly ashes will be performed later.The results of this study will contribute to the better understanding of ash formation processes and improved possibilities to make beneficial use of ashes as an alternative to landfilling.Figure 1. Experimental set-up for investigations of the long-term behaviour of the ashes under different environmental conditions. Figure 2. XRD patterns of RDF fly ashes at different ageing conditions. a) N33, b) N71, c) N15, d) N85, and e) N51. The peaks are labelled A (anhydrite), C (calcite), E (ettringite), F (Friedel's Salt), Ge (gehlenite), H (halite), He (hematite), P (portlandite), Q (quartz), S (sylvite), V (vaterite).

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  • 106. Brännvall, Evelina
    et al.
    Andreas, Lale
    Diener, Silvia
    Tham, Gustav
    Telge AB.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Formation of secondary mineral phases during the ageing of RDF fly ashes2010In: The 6th Intercontinental Landfill Research Symposium, 2010, p. 110-112Conference paper (Other academic)
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  • 107.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andreas, Lale
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Diener, Silvia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Factors influencing chemical and mineralogical changes in RDF fly ashes during aging2014In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 140, no 3, article id 4013014Article in journal (Refereed)
    Abstract [en]

    The effects of aging should be considered for reliable long-term assessments of the environmental risks of the use of refuse-derived-fuel (RDF) fly ash as landfill top cover liner material. Mineral transformations that occur in RDF fly ash, and the effects of selected factors on these transformations, were studied on compacted fly ash specimens in an accelerated aging experiment using a reduced factorial design. Carbon dioxide concentration, temperature, relative air humidity, time, and the quality of added water were varied in six factor combinations. Acid neutralization capacity and leaching behavior were analyzed after four different periods of time. The results were evaluated with multivariate data analysis. A significant change in the acid neutralization capacity, a decrease in leaching of Ba, Ca, Cl − , Cr, Cu, Pb, K, and Na, and an increase in solubility of Mg, Si, Zn, and SO 2− 4 could be attributed to different aging conditions

  • 108.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andreas, Lale
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Changes of fly ash properties during the ageing2015In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 141, no 5, article id 4014083Article in journal (Refereed)
    Abstract [en]

    Aging of refuse-derived fuel (RDF) fly ashes was investigated in a long-term laboratory experiment. Aging affected the chemical stability of RDF fly ash in terms of leaching behavior, ANC, and mineralogical transformations. The design of experiment model evaluation showed that the use of RDF ashes in a top cover liner construction has the following advantages: most of the investigated hazardous elements like Pb, Cl, Cr, Cu, etc., will not be released from the ashes, and their buffer capacity will increase with time. However, aging has the disadvantage that leaching of Zn and SO 4 is likely to increase. The multivariate data analysis of the coefficients of variation did not reveal any systematic errors in the performance of the experiment. However, batch leaching test not always reflect the real situation in the landfill top cover environment.

  • 109.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andreas, Lale
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Travar, Igor
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ageing of ashes in a landfill top cover2011In: SARDINIA 2011: Thirteenth International Waste Management and Landfill Symposium, S. Margherita di Pula, Cagliari, Italy; 3 - 7 October 2011 / [ed] Raffaello Cossu, Cagliari: CISA Publisher, Italy , 2011Conference paper (Refereed)
    Abstract [en]

    This paper is based on studies on the effects of accelerated ageing on refuse-derived-fuel (RDF) fly ashes, in experiments under controlled laboratory conditions, intended to derive models to predict the stability of RDF fly ashes used in a landfill liner and the mineralogi-cal changes that occur in them. A reduced factorial design was applied, followed by multivariate data analysis, to evaluate the effects of five factors — carbon dioxide (CO2) levels, temperature, relative air humidity (RH), time and the quality of added water — on mineral transformations within the ashes, and leaching behaviour. The pH values of these ash specimens ranged from 7.2 to 7.6, indicating advanced carbonation. Ageing decreased pH values from 12.4 to 7.2, conse-quently affecting the leaching behaviour of most chemicals measured in the leachates. Levels of Ba, Ca, Cl, Cr, Cu, Pb, K and Na decreased over the study period while those of Mg, Zn and SO4 increased. Clay minerals could not be detected neither in fresh nor in aged ashes. However, geo-chemical modelling indicated that such minerals may precipitate.

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  • 110.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Belmonte, Carles
    Luleå University of Technology.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Characterisation of waste material mixtures for landfill top cover application2012In: Abstract proceedings of 7th Intercontinental Landfill Research Symposium: Södra Sunderbyn, June 25th to 27th, 2012 / [ed] Anders Lagerkvist, Luleå: Luleå tekniska universitet, 2012, p. 54-Conference paper (Refereed)
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  • 111.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Changes in Element Solubility in Fly Ash and Biosolid Mixtures Used for Soil Fertilization2013In: 12th International Conference on the Biogeochemistry of Trace Elements, Athens, Georgia, USA, June 16-20, 2013, 2013Conference paper (Refereed)
  • 112.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Fly ash in landfill top covers: a review2016In: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 18, no 1, p. 11-21Article in journal (Refereed)
    Abstract [en]

    Increase of energy recovery from municipal solid waste by incineration results in the increased amounts of incineration residues, such as fly ash, that have to be taken care of. Material properties should define whether fly ash is a waste or a viable resource to be used for various applications. Here, two areas of potential fly ash application are reviewed: the use of fly ash in a landfill top cover either as a liner material or as a soil amendment in vegetation layer. Fly ashes from incineration of three types of fuel are considered: refuse derived fuel (RDF), municipal solid waste incineration (MSWI) and biofuel. Based on the observations, RDF and MSWI fly ash is considered as suitable materials to be used in a landfill top cover liner. Whereas MSWI and biofuel fly ashes based on element availability for plant studies, could be considered suitable for the vegetation layer of the top cover. Responsible application of MSWI ashes is, however, warranted in order to avoid element accumulation in soil and elevation of background values over time.

  • 113.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Potential mobility of trace elements in soil as affected by organic matter and redox conditions2011In: 11th International Conference on the Biogeochemistry of Trace Elements, Florence, Italy July 3-7, 2011, 2011Conference paper (Refereed)
  • 114.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Taraškevičius, Ricardas
    Institute of Geology and Geography.
    Zinkutė, Rimante
    Institute of Geology and Geography.
    Spatial variability of topsoil contamination by trace elements on the territories of kindergartens in Vilnius, Lithuania2009In: 10th International Conference on Biogeochemistry of Trace Elements: Frontiers in Trace Elements Research and Education, 2009Conference paper (Other academic)
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  • 115.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nilsson, Malin
    Luleå University of Technology.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Tekedo AB, Nyköping, Sweden.
    Skoglund, Nils
    Umeå University, Umeå, Sweden.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Effect of residue combinations on plant uptake of nutrients and potentially toxic elements2014In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 132, p. 287-295Article in journal (Refereed)
    Abstract [en]

    The aim of the plant pot experiment was to evaluate potential environmental impacts of combined industrial residues to be used as soil fertilisers by analysing i) element availability in fly ash and biosolids mixed with soil both individual and in combination, ii) changes in element phytoavailability in soil fertilised with these materials and iii) impact of the fertilisers on plant growth and element uptake.Plant pot experiments were carried out, using soil to which fresh residue mixtures had been added. The results showed that element availability did not correlate with plant growth in the fertilised soil with. The largest concentrations of K (3534mg/l), Mg (184mg/l), P (1.8mg/l), S (760mg/l), Cu (0.39mg/l) and Zn (0.58mg/l) in soil pore water were found in the soil mixture with biosolids and MSWI fly ashes; however plants did not grow at all in mixtures containing the latter, most likely due to the high concentration of chlorides (82g/kg in the leachate) in this ash. It is known that high salinity of soil can reduce germination by e.g. limiting water absorption by the seeds. The concentrations of As, Cd and Pb in grown plants were negligible in most of the soils and were below the instrument detection limit values.The proportions of biofuel fly ash and biosolids can be adjusted in order to balance the amount and availability of macronutrients, while the possible increase of potentially toxic elements in biomass is negligible seeing as the plant uptake of such elements was low. © 2013 Elsevier Ltd.

  • 116.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Wolters, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Tekedo AB, Spinnarvägen 10, 611 37 Nyköping, Sweden.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Elements availability in soil fertilized with pelletized fly ash and biosolids2015In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 159, p. 27-36Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to evaluate the impact of combined and pelletized industrial residues on availability and mobility of nutrients and potentially toxic elements in soil, plant growth and element uptake. Plant pot experiments were carried out using soil to which 2% of pelletized residue containing biosolids mixed with either municipal solid waste incineration fly ash (MFA) or biofuel fly ash (BFA) was added. The tests showed that the plant growth did not correspond to the content of available nutrients in fertilised soil. MFA application to soil resulted in elevated concentrations of P (506 mg/kg), As (2.7 mg/kg), Cd (0.8 mg/kg) and Pb (12.1 mg/kg) in soil, lower plant uptake of Al (25 mg/kg) and Ba (51 mg/kg), but higher accumulation of As (4.3 mg/kg) and Cd (0.3 mg/kg) in plants compared to the unamended soil and soil amended with BFA. On average, the biomass of the plants grown in the soil containing MFA was larger than in other soils.Considering the use of industrial residue mixtures as soil amendments or fertilizers, the amount of added elements should not exceed those taken up by plants, by this preventing the increase of soil background concentrations.

  • 117.
    Brännvall, Evelina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Zamora, Carles Belmonte
    LTU.
    Sjöblom, Rolf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Effect of industrial residue combinations on availability of elements2014In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 276, p. 171-181Article in journal (Refereed)
    Abstract [en]

    Industrial residues, such as fly ashes and biosolids, contain elements (e.g. N, P, K, S, Ca and Zn) that make them a viable alternative for synthetic fertilizers in forestry and agriculture. However, the use of these materials is often limited due to the presence of potentially toxic substances. It is therefore necessary to assess and, when warranted, modify the chemical and physical form of these and similar waste materials before any advantages are taken of their beneficial properties. Biofuel fly ash, municipal solid waste incineration (MSWI) fly ash, biosolids, peat, peat residues and gypsum board waste were combined in various proportions, and this resulted in increased leaching of N, P, S, Cu and Mn, but decreased leaching of Ca, K, Mg, Cr, Fe, Ni, Zn, Al, As and Pb. Chemical fractionation revealed that elements Ca, K, Mg, S and Mn were predominantly exchangeable, while the rest of the elements were less mobile. Cadmium was mostly exchangeable in MSWI fly ash, but less mobile in biofuel fly ash mixtures. Recycling of MSWI fly ash in the mixtures with fertilizers is considerably less attractive, due to the high levels of salts and exchangeable Cd.

  • 118.
    Brännvall, Rickard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Mattson, Louise
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Lundmark, Erik
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Vesterlund, Mattias
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Data Center Excess Heat Recovery: A Case Study of Apple Drying2020In: ECOS 2020: Proceedings of the 33rd International Conference on Efficiency, Cost, Optimization, Simulation and Enviromental Impact of Energy Systems / [ed] Ryohei Yokoyama, Yoshiharu Amano, ECOS 2020 Local Organizing Committee , 2020, p. 2165-2174Conference paper (Refereed)
    Abstract [en]

    Finding synergies between heat producing and heat consuming actors in an economy provides opportunity for more efficient energy utilization and reduction of overall power consumption. We propose to use low-grade heat recovered from data centers directly in food processing industries, for example for the drying of fruit and berries. This study analyses how the heat output of industrial IT-load on servers can dry apples in a small-scale experimental set up.To keep the temperatures of the server exhaust airflow near a desired set-point we use a model predictive controller (MPC) re-purposed to the drying experiment set-up from a previous work that used machine learning models for cluster thermal management. Thus, conditions with for example 37 C for 8 hours drying can be obtained with results very similar to conventional drying of apples.The proposed solution increases the value output of the electricity used in a data center by capturing and using the excess heat that would otherwise be exhausted. The results from our experiments show that drying foods with excess heat from data center is possible with potential of strengthening the food processing industry and contribute to food self-sufficiency in northern Sweden.

  • 119.
    Bu, Xiangning
    et al.
    School of Chemical Engineering and Technology, China University of Mining and Technology, Jiangsu, Xuzhou, 221116, China.
    Taghizadeh Vahed, Amir
    EPosture AB Luleå, Kvartsstigen 6, SE-977 53, Sweden.
    Ghassa, Sina
    School of Mining, College of Engineering, University of Tehran, Tehran, 16846-13114, Iran.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Modelling of coal flotation responses based on operational conditions by random forest2021In: International Journal of Oil, Gas and Coal Technology, ISSN 1753-3309, E-ISSN 1753-3317, Vol. 27, no 4, p. 457-468Article in journal (Refereed)
    Abstract [en]

    Coal consumption is one of the critical factors in the economy of China. Flotation separation of coal from its inorganic part (ash) can reduce environmental problems of coal consumption and improve its combustion. This investigation used random forest (RF) as an advanced machine learning method to rank flotation operations by variable importance measurement and predict flotation responses based on operational parameters. Fifty flotation experiments were designed, and performed based on various flotation conditions and by different variables (collector dosage, frother dosage, air flowrate, pulp density, and impeller speed). Statistical assessments indicated that there is a significant negative correlation between yield and ash content. Experiments indicated that in the optimum conditions, yield and ash content would be 80 and 9%, respectively. Variable importance measurement by RF showed that frother has the highest effectiveness on yield. Outcomes of modelling released that RF can accurately be used for ranking flotation parameters, and generating models within complex systems in mineral processing.

  • 120.
    Bu, Xiangning
    et al.
    Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
    Zhou, Shaoqi
    Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
    Sun, Meng
    Fengxian Power Supply Co., Ltd., State Grid Jiangsu Electric Power Co., Ltd., Fengxian, Jiangsu 221700, China.
    Alheshibri, Muidh
    Department of Basic Science, Deanship of Preparatory Year and Supporting Studies, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia; Basic & Applied Scientific Research Center, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia.
    Shakhaoath Khan, Md.
    ARC Research Hub for Computational Particle Technology, Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.
    Xie, Guangyuan
    Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Exploring the Relationships between Gas Dispersion Parameters and Differential Pressure Fluctuations in a Column Flotation2021In: ACS Omega, E-ISSN 2470-1343, Vol. 6, no 34, p. 21900-21908Article in journal (Refereed)
    Abstract [en]

    Flotation separation, which is the most important mineral beneficiation technique, is dependent on gas dispersion (hydrodynamic conditions). Thus, many investigations have focused on the precise determination of hydrodynamic conditions such as Reynolds number of the bubbles, bubble velocity, and bubble diameter. However, few studies have examined their relationships with pressure fluctuations in a column flotation. This study introduced the differential pressure fluctuations as an actual variable that could be considered to determine the collection zone’s hydrodynamic conditions in a cyclonic microbubble flotation column. In general, the outcomes indicated that superficial gas velocity had the most substantial relationship with the differential pressure fluctuations among other flotation factors (such as pump speed, superficial gas velocity, superficial water velocity, and frother dosage). Furthermore, a high coefficient of determination (R2 > 0.77) for the equation generated to assess the relationships demonstrated that differential pressure fluctuations could be used as a promising tool to determine the hydrodynamic parameters’ characteristics in the flotation columns. 

  • 121.
    Burnett, Mark
    et al.
    AMC Consultants Limited, UK.
    Zhang, Steven E.
    PG Techno Wox (SmartMin).
    Ghorbani, Yousef
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Bourdeau, Julie E.
    PG Techno Wox (SmartMin).
    Steiner, Benedikt M.
    Has 11 years of global experience in project generation. He has an MSc from the Royal School of Mines, London, and a PhD from the University of Exeter. He is currently Director of the Master's Programme in Exploration and Mining Geology at the, Camborne School of Mines, UK.
    Barnet, James S. K.
    St Andrews, Scotland.
    Nwaila, Glen T.
    University of the Witwatersrand.
    Development of mineral supply and demand from 1950 to 2020: Cold War and consumerism2022In: Routledge Handbook of the Extractive Industries and Sustainable Development / [ed] Natalia Yakovleva; Edmund Nickless, Taylor & Francis Group, 2022, p. 34-60Chapter in book (Other academic)
    Abstract [en]

    The supply and demand of minerals from 1950 to 2020 is examined by focusing on known causal relationships and historical drivers such as the Cold War, and how these have impacted the supply and demand of minerals. The complex, and often fascinating, events that have influenced supply and demand in the minerals market, including geopolitics, environmental policy, high-tech modernization, and the COVID-19 pandemic are reviewed. The examples we provide, focus on the primary consumers in the minerals market, including America, the European Union (EU), and the BRICS (Brazil, Russia, India, China, and South Africa) nations. Fundamental drivers such as sustainability, national defence, and technology are also discussed. This chapter begins with an integrated highlight of the major developments from 1950 to 2020 and then expands on the subject matter in a decadal fashion, providing additional context and detail on the forces and events which have influenced mineral supply and consumption trends.

  • 122.
    Bäck, Oskar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Analysis and optimization of a dissolved air flotation process for separation of suspended solids in wastewater2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Margretelund wastewater treatment plant (WWTP) operated by the water utility Roslagsvatten AB, wasbuilt in 1956 and is located in Åkersberga town, Stockholm County, Sweden. Margretelund WWTP waslast renovated in 1999, and has been operated with the same physical, chemical, and biological processessince then. Due to issues with increased phosphorus emissions connected to increased concentration ofeffluent total suspended solids (TSS), Roslagsvatten would like to optimize the operation of their dissolvedair flotation (DAF) process and the author was tasked to conduct a study about the subject. The specificaim of the study was to propose one method for optimization with available means to reduce effluentTSS concentration during high flow rates for the present DAF process at Margretelund WWTP.Achieving the aim required an historical analysis of Margretelund WWTP’s DAF process and aninvestigation of the effect influent flow rate and effluent recycle rate (ERR) had on effluent TSSconcentration. The increase of effluent TSS was believed to be caused by increased flow rates frominfiltration and inflow (recorded to 32% of total volume the year 2020) affecting the dissolved air flotation(DAF) process.The literature study design parameters for a dissolved air flotation process, specifically the recycle flowpressurization configuration, generated information about which parameters to take into considerationwhen optimizing a DAF unit. Analysis of historic effluent measurements at Margretelund showed that42% of all samples analysed between January 2015 – January 2021 were below 10 mg/l TSS. Eachhistorical increase of surface load has brought a decreased effluent recycle rate (ERR) and consequentlyan increasing percentage of samples exceeding 10 mg/l. A Pearson correlation presented a negativecorrelation with both ERR and surface load in relation to effluent TSS concentration. This resulted inthe selection of the experimental factors ERR and surface load to be investigated in this study.Margretelunds WWTP’s DAF design of ERR being 10-15% and the design surface load of 4 m/h wasthe base values for the experimental runs. Increases of ERR percentage was done during the experimentfor four different surface loads (2.5, 4, 5 and 6 m/h), with five steps between 15% up to 35% ERR inone of the three parallel DAF units in Margretelund WWTP. TSS in the effluent was constantlymonitored using a TSS sensor. Influent TSS was measured at Roslagsvatten’s accredited laboratory in a24h composite sample with 1 hour for each sub-sample.The results showed that both the highest and the lowest ERR settings tested provided the lowest averageeffluent TSS concentrations. However, a decreased surface load was found to lower effluent TSSconcentration and ERR providing only minor differences within each surface load. Largest surface loadpossible was found to be 5 m/h, for an ERR of 15 or 35%. Surface load less than 5 m/h provided aconcentration under 10 mg/l for all ERR setting.

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  • 123.
    Båve, Eric
    Luleå University of Technology.
    Kretslopp och framtidshopp på Tuna: kompostering och växthusodling i kv. Kristallen i Luleå1996Report (Other academic)
  • 124.
    Böckin, Daniel
    et al.
    Divison of Environmental Systems Analysis, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Goffetti, Giulia
    Ecodynamics Group, Department of Earth, Environmental and Physical Sciences, University of Siena, 53100 Siena, Italy.
    Baumann, Henrikke
    Divison of Environmental Systems Analysis, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Tillman, Anne-Marie
    Divison of Environmental Systems Analysis, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Zobel, Thomas
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Business Administration and Industrial Engineering.
    Business model life cycle assessment: A method for analysing the environmental performance of business2022In: Sustainable Production and Consumption, ISSN 2352-5509, Vol. 32, p. 112-124Article in journal (Refereed)
    Abstract [en]

    This paper introduces business model life cycle assessment (BM-LCA), a new method for quantifying the environmental impacts of business models. Such a method is needed to guide business decisions towards decoupling economic activity from environmental impact. BM-LCA takes the business model itself as the unit of analysis and its economic performance as the basis of comparison. It can be applied to any type of business model involving material or resource use. In BM-LCA, monetary flows are coupled to material and energy flows. The methodology expands on conventional life cycle assessment (LCA) by elaborating the goal and scope definition and dividing it into two phases. The first descriptive phase details the business models to be compared. It includes a mapping of product chain actors and identifying business operations and transactions related to the product. The second coupling phase defines a profit-based functional unit and sets up the coupling equations expressing the economic relations to the product. Thereafter, conventional LCA procedures are followed to assess environmental impacts. The key innovation on LCA methodology is the development of a functional unit that captures the economic performance of a business model and links it to a product system. BM-LCA provides thus an important link between LCA and business competitive advantage.

  • 125.
    Cacciarelli, Davide
    et al.
    Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kgs. Lyngby, Denmark; Department of Mathematical Sciences, Norwegian University of Science and Technology, Trondheim, Norway.
    Kulahci, Murat
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Business Administration and Industrial Engineering. Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kgs. Lyngby, Denmark.
    A novel fault detection and diagnosis approach based on orthogonal autoencoders2022In: Computers and Chemical Engineering, ISSN 0098-1354, E-ISSN 1873-4375, Vol. 163, article id 107853Article in journal (Refereed)
    Abstract [en]

    In recent years, there have been studies focusing on the use of different types of autoencoders (AEs) for monitoring complex nonlinear data coming from industrial and chemical processes. However, in many cases the focus was placed on detection. As a result, practitioners are encountering problems in trying to interpret such complex models and obtaining candidate variables for root cause analysis once an alarm is raised. This paper proposes a novel statistical process control (SPC) framework based on orthogonal autoencoders (OAEs). OAEs regularize the loss function to ensure no correlation among the features of the latent variables. This is extremely beneficial in SPC tasks, as it allows for the invertibility of the covariance matrix when computing the Hotelling T2 statistic, significantly improving detection and diagnosis performance when the process variables are highly correlated. To support the fault diagnosis and identification analysis, we propose an adaptation of the integrated gradients (IG) method. Numerical simulations and the benchmark Tennessee Eastman Process are used to evaluate the performance of the proposed approach by comparing it to traditional approaches as principal component analysis (PCA) and kernel PCA (KPCA). In the analysis, we explore how the information useful for fault detection and diagnosis is stored in the intermediate layers of the encoder network. We also investigate how the correlation structure of the data affects the detection and diagnosis of faulty variables. The results show how the combination of OAEs and IG represents a compelling and ready-to-use solution, offering improved detection and diagnosis performances over the traditional methods.

  • 126.
    Carabante, Ivan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Adsorption of As (V) on iron oxide nanoparticle films studied by in situ ATR-FTIR spectroscopy2009In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 346, no 1-3, p. 106-113Article in journal (Refereed)
    Abstract [en]

    Stabilization of arsenic contaminated soils by iron oxides has been proposed as a remediation technique to prevent leaching of arsenate into the environment. Fundamental studies are needed to establish under which conditions the complexes formed are stable. In the present work, a powerful technique, viz. ATR-FTIR spectroscopy, is adapted to studies of adsorption of arsenate species on iron oxides. This technique facilitates acquisition of both quantitative and qualitative in situ adsorption data.In the present work, about 800 nm thick films of 6-lineferrihydrite were deposited on ZnSe ATR crystals. Arsenate adsorption on the ferrihydrite film was studied at pD values ranging from 4 to 12 and at an arsenate concentration of 0.03 mM in D2O solution. The amount of adsorbed arsenate decreased with increasing pD as a result of the more negatively charged iron oxide surface at higher pD values. The adsorption and desorption kinetics were also studied. Arsenate showed a higher adsorption rate within the first 70 minutes and a much lower adsorption rate from 70 up to 300 minutes. The low adsorption rate at longer reaction times was partly due to a low desorption rate of already adsorbed carbonate species adsorbed at the surface. The desorption of carbonate species was evidenced by the appearance of negative absorption bands. The desorption of adsorbed arsenate complexes was examined by flushing with D2O at pD 4 and 8.5 and it was found that the complexes were very stable at pD 4 suggesting formation of mostly inner-sphere complexes whereas a fraction of the complexes at pD 8.5 were less stable than at pD 4, possibly due to the formation of outer-sphere complexes.In summary, the ATR technique was shown to provide in situ information about the adsorption rate, desorption rate and the speciation of the complexes formed within a single experiment, which is very difficult to obtain using other techniques.

  • 127.
    Carabante, Ivan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Influence of Zn(II) on the adsorption of arsenate onto ferrihydrite2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 24, p. 13152-13159Article in journal (Refereed)
    Abstract [en]

    Addition of iron oxide to arsenic-contaminated soil has been proposed as a means of reducing the mobility of arsenic in the soil. Arsenic and zinc are common coexisting contaminants in soils. The presence of zinc therefore may affect the adsorption properties of arsenic on iron oxide, and may thus affect its mobility in the soil. The influence of Zn(II) on the adsorption of arsenate ions on iron oxide was studied. Batch adsorption experiments indicated that Zn(II) increased the arsenate removal from a solution by ferrihydrite at pH 8. However, ATR-FTIR spectroscopy showed that no adsorption of arsenate on a ferrihydrite film occurred at pD 8 in the presence of Zn(II). Precipitation of zinc hydroxide carbonate followed by arsenate adorption onto the precipitate was found to be a plausible mechanism explaining the arsenate removal from a solution in the presence of Zn(II) at pH/pD 8. The previously suggested mechanisms attributing the enhanced removal of arsenate from solution in the presence of Zn(II) to additional adsorption on iron oxides could not be verified under the experimental conditions studied. It was also shown that at pH/pD 4, the presence of Zn(II) in the system did not significantly affect the adsorption of arsenate on ferrihydrite.

  • 128.
    Carabante, Ivan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    A powerful method for studying the adsorption of As(V) on iron oxides in situ2008In: Arsenic in the environment - Arsenic from nature to humans: Book of Abstracts, 2008Conference paper (Other academic)
  • 129.
    Carabante, Ivan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Fredriksson, Andreas
    Mining Technology R and D, LKAB Kiruna Mine.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Reutilization of porous sintered hematite bodies as effective adsorbents for arsenic(V) removal from water2014In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, no 32, p. 12689-12696Article in journal (Refereed)
    Abstract [en]

    A method was developed to enhance the arsenic adsorption capacity of porous bodies of sintered hematite. The method comprised the formation of a coating of 1 wt % iron oxide nanoparticles on the raw material. The nanoparticles showed two distinct habits: spherical habit, likely ferrihydrite, and acicular habit, likely goethite and/or akaganéite. The specific surface area of the hematite raw material increased from 0.5 to 3.75 m2/g, and the adsorption capacity increased from negligible to 0.65 mg of [As]/g as calculated from equilibrium and breakthrough adsorption data. Equilibrium adsorption data of arsenate on the adsorbent from a solution at pH 5 followed the Langmuir model, while breakthrough adsorption data for a 500 μg/L arsenate solution at pH 5 followed the Thomas model. The adsorbed arsenic could be desorbed using distilled water at pH 12. These results show the potential for the reutilization of waste products comprising coarse hematite bodies as adsorbents.

  • 130.
    Carlsson, Isak
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kartläggning och energieffektivisering: KV61, Gärstadverket Linköping2019Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
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  • 131.
    Carlsson, My
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pre-treatment of substrates for anaerobic digestion: potential and development needs2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Substrate pre-treatment has been gaining interest in anaerobic digestion (AD) as a means to increase biogas yields with nowadays more diversified substrate sources. The objective of this thesis is to identify improvement potentials and development needs within applications of substrate pretreatment in anaerobic digestion (AD) based on literature and specific examples, with special focus on the impact assessment and exemplified by the case of electroporation(EP) pre-treatment.The substrate inherent limitations to conversion of organic material to methane include content of non-biodegradable organic compounds, incorporation of biodegradable matter into recalcitrant structures and large particle size. WAS and lignocellulosic material are specific substrates that express significant substrate inherent limitations, especially WAS from WWTPs with long sludge age and lignocellulosic material with high lignin content.Improved AD performance relies on increasing operational methane yield as to approximate as much as possible the actual potential methane yield of the substrate at the highest possible digestion rate. This could potentially be achieved by the application of a pre-treatment, via the mechanisms of particle size reduction/solubilisation of biodegradable/bioavailable matter and/or conversion/exposure of non-biodegradable/non-bioavailable matter as to make it available or degradable. Pre-treatment mechanisms that could potentially counteract these effects are the removal of organic matter and/or the formation of refractory compounds. Pre-treatment by electroporation has the potential to affect substrates and, in some cases improve AD process performance. However, the effect of a specific pre-treatment may differ depending on the type of substrate upon which it is applied. The assessment of pre-treatment effects may be performed on different levels, representing impacts from micro to macro scale. On a substrate level, COD solubilisation is commonly measured, but the interpretation is aggravated by the application of different measurement approaches. In addition, solubilisation of COD as a result of pre-treatment does not necessarily translate into increased operational methane yield, and vice versa, the increased operational yield is not necessarily caused by increased COD solubilisation. On an AD process performance level, BMP tests have been used to assess both increased biodegradability and increased rate of degradation. Both applications rely on appropriate set-up as well as understanding of the limitations of the test. Substrate pre-treatment affects the quality of the outputs as well as the downstream processes of an AD process. A systematic approach is therefore necessary to understand how the introduction of a pre-treatment process as well as the changes in process performance with respect to qualities and quantities of outputs affect the balances of the system with respect to assessment bases such as energy, CO2 or economics.Several areas that would gain from further development can be identified within the area of substrate pre-treatment. These include improved understanding of substrate characteristics with improved descriptors, such as improved understanding of COD composition, and of BMP applicability and limitations. In addition, improved understanding of the relationship between substrate composition and process performance would be helpful to improve the understanding of different pre-treatment effects.Improved understanding of system effects where case-specific conditions can be considered is necessary for the full-scale implementation of pre-treatments to a larger extent. The application of tools for systems analysis to systems including pre-treatment should be further evaluated and a sensitivity analysis with respect to which specific conditions may render pre-treatments beneficial or non-beneficial should be performed.The practical applicability of electroporation pre-treatment for different substrates needs further development and the energy efficiency of the pre-treatment should be evaluated considering upscaling effects.

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  • 132.
    Carlsson, My
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    When and why is pre-treatment of substrates for anaerobic digestion useful?2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Anaerobic digestion (AD) plays a key role in the recovery of renewable energy, in the form of biogas, and nutrients from waste materials. Pre-treatment of AD substrates has the potential to improve process performance in terms of increased methane yield and solids reduction, but pretreatments are not yet widely implemented into full-scale AD systems. The aims of this thesis were to identify conditions that determine when pre-treatment has a positive impact on an AD system and ways to improve the practical utility of pre-treatment impact assessment. Key steps towards meeting these aims were to determine and critically analyse effects of pre-treatments on AD, and current evaluation schemes at three levels: AD substrate level – Direct effects on the substrate’s chemical and physical characteristics and its biodegradability/bioavailability; Local AD system level – Effects of pre-treatment on the AD process and its outputs, required inputs and (local) upstream and downstream processes. System boundaries are “at the gate” of the AD plant and the system analysis may consider energy and/or financial parameters; Expanded AD System level – Includes indirect effects of pre-treatment, with system boundaries including external processes. The system analysis may address environmental and/or economic effects. Different substrate traits represent different types and degrees of limitations to optimal AD performance that can be met by different pre-treatment mechanisms. Most importantly, potential mechanical problems must be handled by dilution and/or homogenisation and unwanted components, as generally found in source-sorted food waste from households (FW), must be separated. These traits may hinder the actual operation of AD and the potential for recovery of nutrients, which is often the motivation for biological waste treatment. When these practical barriers are overcome, pre-treatment focus may be directed towards maximizing the conversion of organic material to biogas, which is potentially limited by the rate and/or extent of hydrolysis. Lignocellulosic structures and aerobically stabilised biological sludge represent significant barriers to hydrolysis, which can be overcome by pre-treatment-induced solubilisation. Other particulates are merely hydrolysis-limited by their size, which can be reduced by specific pre-treatments. Finally, substrates may contain non-biodegradable organic compounds, which need to be chemically transformed in order to be converted to biogas. The substrates considered for AD incorporate these traits in varying degrees and even among substrates of the same category, such as plant material and excess sludge from wastewater treatment (WWT), the potential effect of pretreatments may vary considerably. Overcoming the substrate barriers via pre-treatment may potentially improve the AD system by enhancing operational stability, increasing methane yields and solids reduction under similar operating conditions to those without pre-treatment or by increasing methane productivity by allowing reductions in hydraulic retention time without changing the methane yield. However, the required inputs as well as the associated effects on related sub-processes must also be considered. The ultimate usefulness of a pre-treatment in a specific system is determined by the mass- and energy balance and the associated financial or environmental costs/values of inputs and outputs. The accuracy and applicability of pre-treatment impact assessment is challenged by method limitations and lack of transparency. A common measure of the pre-treatment effects is COD solubilisation, but the interpretation is complicated by the application of different measurementapproaches. In addition, solubilisation of COD as a result of pre-treatment does not necessarily translate into increases in operational methane yields. This is due to potential formation of refractory compounds and the fact that hydrolysis is not necessarily rate limiting for all particulates. Pre-treatments’ effects on biodegradability and degradation rates can be better assessed by BMP tests (biochemical methane potential), provided that the test conditions are appropriate and the tests’ limitations are properly considered. However, extrapolation of BMP results to continuous processes is complicated by the batch mode of the tests. On the other hand, results from continuous trials allow assessments of methane yields in practical systems and the digestate’s physico-chemical properties, but are inevitably tied to the specific process conditions tested. Thus, results from multiple experimental conditions, possibly strengthened by computer simulations, are necessary for generalisations of pre-treatment effects on AD process performance. Pre-treatments have the potential to considerably improve AD systems, but their implementation must to be guided by the actual improvement potential of the specific substrate and valued in theirspecific context with respect to process design and framework conditions.

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  • 133.
    Carlsson, My
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Holmström, David
    Profu AB, Mölndal.
    Bohn, Irene
    NSR, North Western Scania Waste Management Company, Helsingborg.
    Bisaillon, Mattias
    Profu AB, Mölndal.
    Morgan-Sagastume, Fernando
    AnoxKaldnes AB, Klosterängsvägen 11A, 226 47 Lund.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Impact of physical pre-treatment of source-sorted organic fraction of municipal solid waste on greenhouse-gas emissions and the economy in a Swedish anaerobic digestion system2015In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 38, p. 117-125Article in journal (Refereed)
    Abstract [en]

    Several methods for physical pre-treatments of source sorted organic fraction of municipal solid waste (SSOFMSW) before for anaerobic digestion (AD) are available, with the common feature that they generate a homogeneous slurry for AD and a dry refuse fraction for incineration. The selection of efficient methods relies on improved understanding of how the pre-treatment impacts on the separation and on the slurry’s AD. The aim of this study was to evaluate the impact of the performance of physical pre-treatment of SSOFMSW on greenhouse-gas (GHG) emissions and on the economy of an AD system including a biogas plant with supplementary systems for heat and power production in Sweden. Based on the performance of selected Swedish facilities, as well as chemical analyses and BMP tests of slurry and refuse, the computer-based evaluation tool ORWARE was improved as to accurately describe mass flows through the physical pre-treatment and anaerobic degradation. The environmental and economic performance of the evaluated system was influenced by the TS concentration in the slurry, as well as the distribution of incoming solids between slurry and refuse. The focus to improve the efficiency of these systems should primarily be directed towards minimising the water addition in the pre-treatment provided that this slurry can still be efficiently digested. Second, the amount of refuse should be minimised, while keeping a good quality of the slurry. Electricity use/generation has high impact on GHG emissions and the results of the study are sensitive to assumptions of marginal electricity and of electricity use in the pre-treatment.

  • 134. Carlsson, My
    et al.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ecke, Holger
    Electroporation for enhanced methane yield from municipal solid waste2008Conference paper (Refereed)
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  • 135.
    Carlsson, My
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Veolia Water Technologies AB (AnoxKaldnes), Lund, Sweden.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Morgan-Sagastume, Fernando
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Veolia Water Technologies AB (AnoxKaldnes), Lund, Sweden.
    Energy balance performance of municipal wastewater treatment systems considering sludge anaerobic biodegradability and biogas utilisation routes2016In: Journal of Environmental Chemical Engineering, E-ISSN 2213-3437, Vol. 4, no 4, p. 4680-4689Article in journal (Refereed)
    Abstract [en]

    The energy balance of a municipal wastewater treatment (WWT) system was evaluated considering the influence of excess biological sludge anaerobic biodegradability (BDAn) and of biogas utilisation as either fuel for co-generation of heat and power (CHP) or for vehicle transport. Sludge thermal pre-treatment prior to anaerobic digestion and high-rate carbon removal were considered as modifications of a reference municipal WWT system to impact the sludge BDAn. Both thermal pre-treatment and a high-rate process with a short sludge retention time (SRT = 1-3d) led to ∼30% higher sludge BDAn than that of untreated sludge from a low-rate WWT system with long SRT ( > 8d), which enhanced methane yields and energy production correspondingly. An efficient separation (40% of CODin) of primary solids promoted biogas production by capturing a significant part of the incoming COD, and lowered aeration energy demands for carbon oxidation due to lower loads of particulate organics into the biological treatment. Thermal pre-treatment can most effectively increase the biodegradability of sludge originating from a low-rate WWT system with a long SRT. Sludge solubilization alone as an indicator of increase biodegradability by a pre-treatment is inadequate for sludge types with inherently high biodegradability. A WWT system with primary separation, sludge pre-treatment, and CHP from biogas can be a net electricity producer and self-sufficient in thermal energy, provided the thermal energy from CHP is available for the pre-treatment. With other types of energy carriers as inputs and outputs, the WWT performance also needs evaluation with respect to the energy economic and environmental value. 

  • 136.
    Carlsson, My
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Morgan-Sagastume, Fernando
    AnoxKaldnes AB.
    The effects of substrate pre-treatment on anaerobic digestion systems: a review2012In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 32, no 9, p. 1634-1650Article in journal (Refereed)
    Abstract [en]

    Focus is placed on substrate pre-treatment in anaerobic digestion (AD) as a means of increasing biogas yields using today’s diversified substrate sources. Current pre-treatment methods to improve AD are being examined with regard to their effects on different substrate types, highlighting approaches and associated challenges in evaluating substrate pre-treatment in AD systems and its influence on the overall system of evaluation. WWTP residues represent the substrate type that is most frequently assessed in pre-treatment studies, followed by energy crops/harvesting residues, organic fraction of municipal solid waste, organic waste from food industry and manure. The pre-treatment effects are complex and generally linked to substrate characteristics and pre-treatment mechanisms. Overall, substrates containing lignin or bacterial cells appear to be the most amendable to pre-treatment for enhancing AD. Approaches used to evaluate AD enhancement in different systems is further reviewed and challenges and opportunities for improved evaluations are identified.

  • 137.
    Carlsson, My
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Naroznova, Irina
    Department of Environmental Engineering (DTU Environment), Technical University of Denmark.
    Möller, Jacob Steen
    Department of Environmental Engineering (DTU Environment), Technical University of Denmark.
    Scheutz, Charlotte
    Department of Environmental Science and Engineering, Technical University of Denmark.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Importance of food waste pre-treatment efficiency for global warming potential in life cycle assessment of anaerobic digestion systems2015In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 102, p. 58-66Article in journal (Refereed)
    Abstract [en]

    A need for improvement of food waste (FW) pre-treatment methods has been recognized, but few life cycle assessments (LCA) of FW management systems have considered the pre-treatment with respect to input energy, loss of organic material and nutrients for anaerobic digestion (AD) and/or further treatment of the refuse. The objective of this study was to investigate how FW pre-treatment efficiency impacts the environmental performance of waste management, with respect to global warming potential (GWP). The modeling tool EASETECH was used to perform consequential LCA focusing on the impact of changes in mass distribution within framework conditions that were varied with respect to biogas utilization and energy system, representing different geographical regions and/or different time-frames. The variations of the GWP due to changes in pre-treatment efficiency were generally small, especially when biogas and refuse were substituting the same energy carriers, when energy conversion efficiencies were high and slurry quality good enough to enable digestate use on land. In these cases other environmental aspects, economy and practicality could be guiding when selecting pre-treatment system without large risk of sub-optimization with regards to GWP. However, the methane potential of the slurry is important for the net LCA results and must be included in the sensitivity analysis. Furthermore, when biogas is used as vehicle fuel the importance of pre-treatment is sensitive to assumptions and approach of modelling marginal energy which must be decided based on the focus and timeframe of the study in question

  • 138.
    Carvalho, Lara
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Opportunities to broaden biomass feedstocks in thermochemical conversion technologies2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Global environmental concerns are motivating a growing interest in broadening the biomass feedstock base in several energy sectors, including (i) the domestic heating sector, presently dominated by stem wood combustion, and (ii) biofuel production, presently dominated by edible crops. The objective of this thesis is to investigate new opportunities to broaden the biomass feedstock in thermochemical conversion technologies. The performance of different feedstocks was therefore investigated for (i) heat production in small-scale combustion systems and (ii) biofuel production in large-scale gasification-based plants. The selected feedstocks were agricultural residues, forest wood, pyrolysis liquid and industrial by-products, such as lignin, black liquor, crude glycerol and fermentation residues.

    The alkali metals content in biomass has an important role in combustion and gasification. Alkali metals can cause ash-related problems in small-scale combustion systems, while they can catalyse gasification reactions thus increasing conversion efficiency. Keeping this effect in mind, the present investigation was based on combustion tests with pelletised agricultural residues (non-woody feedstocks with ash contents of 3-8 wt% on a dry basis) to evaluate their combustion feasibility in several small-scale appliances. Moreover, the potential techno-economic benefits of alkali addition in gasification-based biofuel plants were investigated in two different systems: (i) stand-alone biofuel plant operated with wet-alkali-impregnated forest residues and alkali-rich lignin as well as (ii) biofuel plant integrated with a Kraft pulp mill operated with black liquor (an inherently alkali-rich feedstock) mixed with different blend ratios of pyrolysis liquid, crude glycerol or fermentation residues (co-gasification concept). The techno-economic analysis in large-scale entrained-flow-gasification-based biofuel plants was made with the help of simulation tools.

    The combustion tests have shown that high alkali feedstocks lead to problems with ash accumulation and slag formation in small-scale appliances. The results indicated that non-woody feedstocks can only be burned in appliances adapted to manage high ash content feedstocks. Effective ash cleaning and enhanced combustion controlling mechanisms are relevant characteristics to have in appliances when using these feedstocks. It has been shown that four out of the seven selected feedstocks can be burned in small-scale appliances, while fulfilling the legal European requirements (EN 303-5:2012) in terms of combustion efficiency and emissions. The nitrogen content and ash composition were shown to be important parameters to evaluate whether a feedstock can be utilised in small-scale combustion appliances.

    The techno-economic investigations of the gasification-based biofuel plants have shown that alkali impregnation is an attractive option to increase energy performance and downstream biofuel production. The economic assessment has indicated that alkali impregnation does not significantly increase biofuel production costs, while it allows the application of a new syngas cleaning system that can significantly reduce biofuel production costs. The present study has shown that the vi co-gasification concept has also techno-economic benefits as a result of the (i) alkali content in black liquor and (ii) economy-of-scale effects. These benefits can be enhanced by choosing energy-rich and low-cost blend-in feedstocks. The gasification-based biofuel production routes hereby investigated exhibit a good economic performance since biofuel required selling prices were economically competitive with other biofuel production routes as well as with taxed gasoline.

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  • 139.
    Carvalho, Lara
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. IVL – Swedish Environmental Institute, Stockholm, Sweden.
    Ma, Chunyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Öhrman, Olov G. W.
    IVL – Swedish Environmental Institute, Stockholm, Sweden;RISE Energy Technology Center AB, Piteå, Sweden.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Alkali enhanced biomass gasification with in situ S capture and a novel syngas cleaning: Part 2: Techno-economic analysis2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 165, no Part B, p. 471-482Article in journal (Refereed)
    Abstract [en]

    Previous research has shown that alkali addition has operational advantages in entrained flow biomass gasification and allows for capture of up to 90% of the biomass sulfur in the slag phase. The resultant low-sulfur content syngas can create new possibilities for syngas cleaning processes. The aim was to assess the techno-economic performance of biofuel production via gasification of alkali impregnated biomass using a novel gas cleaning systemcomprised of (i) entrained flow catalytic gasification with in situ sulfur removal, (ii) further sulfur removal using a zinc bed, (iii) tar removal using a carbon filter, and (iv) CO2 reductionwith zeolite membranes, in comparison to the expensive acid gas removal system (Rectisol technology). The results show that alkali impregnation increases methanol productionallowing for selling prices similar to biofuel production from non-impregnated biomass. It was concluded that the methanol production using the novel cleaning system is comparable to the Rectisol technology in terms of energy efficiency, while showing an economic advantagederived from a methanol selling price reduction of 2–6 €/MWh. The results showed a high level of robustness to changes related to prices and operation. Methanol selling prices could be further reduced by choosing low sulfur content feedstocks.

  • 140.
    Carvalho, Lara
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wolf, Jens
    RISE Bioeconomy.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Methanol production via black liquor co-gasification with expanded raw material base: Techno-economic assessment2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 225, p. 570-584Article in journal (Refereed)
    Abstract [en]

    Entrained flow gasification of black liquor combined with downstream-gas-derived synthesis of biofuels in Kraft pulp mills has shown advantages regarding energy efficiency and economic performance when compared to combustion in a recovery boiler. To further increase the operation flexibility and the profitability of the biofuel plant while at the same time increase biofuel production, black liquor can be co-gasified with a secondary feedstock (blend-in feedstock). This work has evaluated the prospects of producing biofuels via co-gasification of black liquor and different blend-in feedstocks (crude glycerol, fermentation residues, pyrolysis liquids) at different blend ratios. Process modelling tools were used, in combination with techno-economic assessment methods. Two methanol grades, crude and grade AA methanol, were investigated. The results showed that the co-gasification concepts resulted in significant increases in methanol production volumes, as well as in improved conversion efficiencies, when compared with black liquor gasification; 5-11 and 4-10 percentage point in terms of cold gas efficiency and methanol conversion efficiency, respectively. The economic analysis showed that required methanol selling prices ranging from 55-101 €/MWh for crude methanol and 58-104 €/MWh for grade AA methanol were obtained for an IRR of 15%. Blend-in led to positive economies-of-scale effects and subsequently decreased required methanol selling prices, in particular for low cost blend-in feedstocks (prices below approximately 20 €/MWh). The co-gasification concepts showed economic competitiveness to other biofuel production routes. When compared with fossil fuels, the resulting crude methanol selling prices were above maritime gas oil prices. Nonetheless, for fossil derived methanol prices higher than 80 €/MWh, crude methanol from co-gasification could be an economically competitive option. Grade AA methanol could also compete with taxed gasoline. Crude glycerol turned out as the most attractive blend-in feedstock, from an economic perspective. When mixed with black liquor in a ratio of 50/50, grade AA methanol could even be cost competitive with untaxed gasoline.

  • 141.
    Chamkhorami, Khosro Soleimani
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Faculty of Computer Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran.
    Kasraei, Ahmad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Garmabaki, Amir Soleimani
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Implications of Climate Change in Life Cycle Cost Analysis of Railway Infrastructure2023In: Proceedings of the 33rd European Safety and Reliability Conference (ESREL 2023) / [ed] Mário P. Brito; Terje Aven, Piero Baraldi; Marko Čepin; Enrico Zio, Research Publishing , 2023, p. 2089-2096, article id P093Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Extreme weather conditions from climate change, including high or low temperatures, snow and ice, flooding,storms, sea level rise, low visibility, etc., can damage railway infrastructure. These incidents severely affect the reliability of the railway infrastructure and the acceptable service level. Due to the inherent complexity of the railway system, quantifying the impacts of climate change on railway infrastructure and associated expenses has been challenging. To address these challenges, railway infrastructure managers must adopt a climate-resilient approach that considers all cost components related to the life cycle of railway assets. This approach involves implementing climate adaptation measures to reduce the life cycle costs (LCC) of railway infrastructure while maintaining the reliability and safety of the network. Therefore, it is critical for infrastructure managers to predict, "How will maintenance costs be affected due to climate change in different RCP's scenarios?"The proposed model integrates operation and maintenance costs with reliability and availability parameters such as mean time to failure (MTTF) and mean time to repair (MTTR). The proportional hazard model (PHM) is used to reflect the dynamic effect of climate change by capturing the trend variation in MTTF and MTTR. A use case from a railway in North Sweden is studied and analyzed to validate the process. Data collected over a 20-year period is analyzed for the chosen use case. As a main result, this study has revealed that climate change may significantly influence the LCC of switch and crossing (S&C) and can help managers predict the required budget.

  • 142.
    Chehreh Chelgani, Saeed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Wallenberg Initiative Materials Science for Sustainability, Department of Civil, Environmental and Natural Resources Engineering, Swedish School of Mines, Luleå University of Technology, Luleå, Sweden.
    Homafar, Arman
    Electrical and Computer Engineering Department, Semnan University, Semnan, Iran.
    Nasiri, Hamid
    Department of Computer Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.
    Rezaei laksar, Mojtaba
    Delijan Copper Flotation Company, Delijan, Iran.
    CatBoost-SHAP for modeling industrial operational flotation variables – A “conscious lab” approach2024In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 213, article id 108754Article in journal (Refereed)
    Abstract [en]

    Flotation separation is the most important upgrading critical raw material technique. Measuring interactions within flotation variables and modeling their metallurgical responses (grade and recovery) is quite challenging on the industrial scale. These challenges are because flotation separation includes several sub-micron processes, and their monitoring won't be possible for the processing plants. Since many flotation plants are still manually operating and maintaining, understanding interactions within operational variables and their effect on the metallurgical responses would be crucial. As a unique approach, this study used the “Conscious Lab” concept for modeling flotation responses of an industrial copper upgrading plant when Potassium Amyl Xanthate substituted the secondary collector (Sodium Ethyl Xanthate) in the process. The main aim is to understand and compare interactions before and after the collector substitution. For the first time, the conscious lab was constructed based on the most advanced explainable artificial intelligence model, Shapley Additive Explanations, and Catboost. Catboost- Shapley Additive Explanations could accurately model flotation responses (less than 2% error between actual and predicted values) and illustrate variations of complex interactions through the substitution. Through a comparative study, Catboost could generate more precise outcomes than other known artificial intelligence models (Random Forest, Support Vector Regression, Extreme Gradient Boosting, and Convolutional Neural Network). In general, substituting Sodium Ethyl Xanthate by Potassium Amyl Xanthate reduced process predictability, although Potassium Amyl Xanthate could slightly increase the copper recovery.

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  • 143.
    Chelgani, S. Chehreh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Nasiri, H.
    Department of Computer Engineering, Amirkabir University of Technology, Tehran, Iran.
    Alidokht, M.
    Tabas Parvardeh Coal Company (TPCCO), Birjand, Iran.
    Interpretable modeling of metallurgical responses for an industrial coal column flotation circuit by XGBoost and SHAP-A “conscious-lab” development2021In: International Journal of Mining Science and Technology, ISSN 2095-2686, Vol. 31, no 6, p. 1135-1144Article in journal (Refereed)
    Abstract [en]

    Surprisingly, no investigation has been explored relationships between operating variables and metallurgical responses of coal column flotation (CF) circuits based on industrial databases for under operation plants. As a novel approach, this study implemented a conscious-lab “CL” for filling this gap. In this approach, for developing the CL dedicated to an industrial CF circuit, SHapley Additive exPlanations (SHAP) and extreme gradient boosting (XGBoost) were powerful unique machine learning systems for the first time considered. These explainable artificial intelligence models could effectively convert the dataset to a basis that improves human capabilities for better understanding, reasoning, and planning the unit. SHAP could provide precise multivariable correlation assessments between the CF dataset by using the Tabas Parvadeh coal plant (Kerman, Iran), and showed the importance of solid percentage and washing water on the metallurgical responses of the coal CF circuit. XGBoost could predict metallurgical responses (R-square > 0.88) based on operating variables that showed quite higher accuracy than typical modeling methods (Random Forest and support vector regression).

  • 144.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Estimation of gross calorific value based on coal analysis using an explainable artificial intelligence2021In: Machine Learning with Applications, ISSN 2666-8270, Vol. 6, article id 100116Article in journal (Refereed)
    Abstract [en]

    Developing fuel resources is strategically crucial for Armenia. Far more than any other fossil fuel resource, coal roughly generates half the nation’s electricity. Although coal could play a critical role, no vast data is available about Armenia coal properties. Using robust modeling of energy indexes such as coal gross calorific value (GCV) by considering trivial existing datasets could be an essential clue for ensuring sustainable development. For the first time, this investigation is going to model GCV for Armenia coal samples. For this purpose, SHAP (SHapley Additive exPlanations) as a novel explainable artificial intelligence will be introduced. SHAP enables understanding the magnitude of relationships between each individual input record and its representative output and ranks input variables based on their effectiveness. SHAP was coupled by extreme gradient boosting (xgboost) as the most recently generated powerful predictive machine learning tool (SHAP-Xgboost). SHAP-Xgboost could accurately (R2=0.99) model GCV based on proximate and ultimate variables of Armenia coal samples. These significant outcomes open a new window for developing high interpretability models to assess coal properties and pinpoint the influential parameters.

  • 145.
    Chelgani, Saeed Chehreh
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Dehghan, F.
    Department of Computer engineering, Jajarm Branch, Islamic Azad University, Iran.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Estimation of some coal parameters depending on petrographic and inorganic analyses by using Genetic algorithm and adaptive neuro-fuzzy inference systems2011In: Energy Exploration and Exploitation, ISSN 01445987, Vol. 29, no 4, p. 479-494Article in journal (Refereed)
    Abstract [en]

    Adaptive neuro-fuzzy inference systems (ANFIS) in combination with genetic algorithm (GA); provide valuable modeling approaches of complex systems for a wide range of coal samples. Evaluation of this combination (GA-ANFIS) showed that the GA-ANFIS approach can be utilized as an efficient tool for describing and estimating some of coal variables such as Hardgrove grindability index, gross calorific value, free swelling index, and maximum vitrinite reflectance with various coal analyses (proximate, ultimate, elemental, and petrographic analysis). Statistical factors (correlation coefficient, mean square error, and variance accounted for) and differences between actual and predicted values demonstrated that the GA-ANFIS can be applied successfully, and provide high accuracy for prediction of those coal variables.

  • 146.
    Chelgani, Saeed Chehreh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Hadavandi, Esmaeil
    Department of Industrial Engineering, Birjand University of Technology, Birjand, Iran.
    Hower, James C.
    Center for Applied Energy Research, University of Kentucky, Lexington, KY, USA.
    Estimation of heavy and light rare earth elements of coal by intelligent methods2021In: Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, ISSN 1556-7036, E-ISSN 1556-7230, Vol. 43, no 1, p. 70-79Article in journal (Refereed)
    Abstract [en]

    Since last two decades, several investigations in various countries have been started to discover new rare earth element (REE) resources. It was reported that coal can be considered as a possible source of them. REE of coal occur in low concentrations, and their detection is a complicated process; therefore, their predictions based on conventional coal properties (proximate, ultimate and major elements (ME)) may have several advantages. However, few studies have been conducted in this area. This study examined relationships between coal properties and REE (HREE and LREE) for a wide range of coal samples (708 samples). Variable importance measure (VIM) by Mutual information (MI) as a new feature selection method was applied to consider the heterogeneous structure of coal and assess the individual relation between coal parameters and REE to select the compact subsets as input variables for modeling and improve the performance of prediction. VIM by MI showed that Si-Carbon, and Al-Hydrogen are the best subsets for the prediction of HREE and LREE concentrations, respectively. A boosted neural network (BNN) model as a new predictive tool was used for REE prediction. BNN can significantly reduce generalization of error. Results of BNN models showed that the HREE and LREE concentrations can satisfactory estimate (R 2 : 0.83 and 0.89, respectively). Results of this investigation were approved that MI-BNN can be used as a potential tool for prediction of other complex problems in energy and fuel areas.

  • 147.
    Chelgani, Saeed Chehreh
    et al.
    University of Michigan, Ann Arbor, USA.
    Hart, B.
    University of Western Ontario, Ontario N6G0J3, Canada.
    Explaining surface interactions for common associated gangues of rare earth minerals in response to the oxalic acid2018In: International Journal of Mining Science and Technology, ISSN 2095-2686, Vol. 28, no 2, p. 343-346Article in journal (Refereed)
    Abstract [en]

    In the flotation of rare earth minerals (REMs), oxalic acid is reportedly acting both as a depressant and pH modifier. Although results of testing have established the significance of oxalic acid in the flotation process, its specific role in either the recovery or selectivity of REMs over their common gangue minerals is not well understood. Pulp pH reduction trials with alternative acids have not shown the same effect on the REMs recovery or the depression of gangue phases. This work studies the effect of oxalic acid on the surface of common REMs gangue minerals (quartz and carbonates (dolomite and calcite)) in a series of conditioning tests. Gangue surface analyses by time of flight secondary ion mass spectroscopy (TOF-SIMS) indicate that oxalic acid inhibits the transfer of secondary ions generated during the conditioning process from one mineral to another. In this regard, the oxalate anion acts to fix ions in solution through chelation, limiting their participation in surface adsorption.

  • 148.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, Research Park, University of Western Ontario, Canada.
    Hart, B.
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Marois, J.
    Niobec Inc., Canada.
    Ourriban, M.
    Niobec Inc., Canada.
    Study of pyrochlore matrix composition effects on froth flotation by SEM-EDX2012In: Minerals Engineering, ISSN 0892-6875, Vol. 30, p. 62-66Article in journal (Refereed)
    Abstract [en]

    Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM–EDX) was used to analyse pyrochlore grains from Niobec froth flotation plant. Approximately 200 pyrochlore gains from the mill feed, pyrochlore rougher feed, pyrochlore rougher concentrate, and tail were analysed in order to identify a potential relationship between pyrochlore matrix composition and selective separation. Analyses indicate that pyrochlore grains with high Fe content appear to be less recoverable than those with a lower Fe content. Furthermore, analysis indicates that the flotation response is related to matrix Fe rather than Fe occurring as inclusions within the pyrochlore. These mineralogical investigation results are from a much larger program where pyrochlore matrix composition will be examined in relation to surface chemistry and flotation selectivity.

  • 149.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, Research Park, University of Western Ontario, Canada.
    Hart, B.
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Marois, J.
    Niobec Inc., Canada.
    Ourriban, M.
    Niobec Inc., Canada.
    Study of pyrochlore surface chemistry effects on collector adsorption by TOF-SIMS2012In: Minerals Engineering, ISSN 0892-6875, Vol. 39, p. 71-76Article in journal (Refereed)
    Abstract [en]

    Time of flight secondary ion mass spectrometry (TOF-SIMS) was used to analyse the surface of two different types of pyrochlore, high Fe pyrochlore and low Fe pyrochlore, from Niobec Saint-Honore mine deposit. Pyrochlore grains were analysed in order to identify a potential relationship between pyrochlore matrix composition, the corresponding surface expression and the related effect on cationic collector adsorption. TOF-SIMS analyses of pyrochlore surfaces from a conditioning test show that the species indicative of the cationic collector, favour the surface of Fe poor pyrochlore relative to the Fe rich variety. Lower collector signals on the surface of the Fe-pyrochlore are matched by higher relative intensities of Fe, OH, O and FeOH. The TOF-SIMS results illustrate a negative relationship between a cationic collector adsorption and the presence of Fe and Fe oxidation species on the surface of pyrochlore grains, and supports previous work which identified a negative correlation between matrix Fe content and pyrochlore floatability. The surface analysis illustrates the link between pyrochlore matrix chemistry, the expression of surface species and their effect on collector adsorption.

  • 150.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, Research Park, University of Western Ontario, Canada.
    Hart, B.
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Marois, J.
    Niobec Inc., Canada.
    Ourriban, M.
    Niobec Inc., Canada.
    Study the relationship between the compositional zoning of high iron content pyrochlore and adsorption of cationic collector2013In: Minerals Engineering, ISSN 0892-6875, Vol. 46-47, p. 34-37Article in journal (Refereed)
    Abstract [en]

    The matrix composition and surface chemistry of high iron pyrochlore (Fe pyrochlore) grains from Niobec (St-Horone carbonatite deposit) were analyzed, in order to identify a potential relationship between Fe pyrochlore matrix composition and the related effect on cationic collector adsorption (tallow diamine). SEM–EDX analyses indicate compositional zoning in the structure Fe pyrochlores. TOF-SIMS was used to analyse the surface of different compositional zones of Fe pyrochlore, in order to identify their related effects on tallow diamine adsorption. Surface analyses of high and low iron zones of treated Fe pyrochlore show that species indicative of the collector favour the regions of low iron content The low iron areas also show a lower relative proportion of species indicative of oxidation. This study identifies the link between Fe pyrochlore compositional zoning, surface oxidation and, area selective collector loading.

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