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  • 1.
    Andersson, Jasmine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Investigation of carbon capture technologies for Sävenäs waste-to-energy plant2020Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
    Abstract [en]

    Carbon capture technologies have the potential to decarbonize the emissions to air from the heat and power sector and contribute to the necessary greenhouse gas emission mitigation in order to meet the Paris Agreement requirements. The energy requirement and ability to retrofit carbon capture units are crucial to convert existing power plants into more environmental benign processes to meet the Swedish national goal of greenhouse gas neutrality at 2045. This report investigates the viability of carbon capture technologies at waste-to-energy (WTE) plants with a techno-economic analysis of the Sävenäs WTE plant in Gothenburg. Flue gas characteristics at WTE plants, with a carbon dioxide (CO2) concentration of ~10%, facilitates absorption techniques for post-combustion capturing which offers a high level of readiness and large-scale operations compared to other capture technologies.  

    To assess the feasibility of the carbon capture options, multicriteria aspects were considered covering energy requirement, environmental impact as well as economic advantages and disadvantages associated with CO2 emission abatement and loss of income due to energy withdrawal. Mass and energy balance calculations were executed based on steady-state assumptions and conservation of mass and energy in order to develop process models for carbon capture and thus expose process integration possibilities and the energy recovery potential. The balance calculations were performed for Monoethanolamine (MEA) and Chilled Ammonia Process (CAP) as they were the most promising absorption technologies at the time of this master thesis project.

    The calculations show that the energy efficiency at Sävenäs WTE plant is reduced by 32% using MEA solution on a yearly average. However, extensive energy recovery would be achieved by integrating a heat-pump to the treatment process combined with district heating integration. With this integration the energy efficiency was reduce only by 12%. Energy penalty associated with CAP was found to reduce the efficiency by 21%. Energy recovery solutions are primarily derived from district heating integration which result in a net energy efficiency reduction by 10%.

    Due to its location in Sweden the demand of heat produced at Sävenäs WTE plant is at its highest between October and March. The CO2 emission abatement and cost analysis showed that a carbon capture facility is preferable operating during summertime when most of the about 1.5 TWh heat distributed per year from Sävenäs WTE plant won’t have to be replaced with other less environmental benign and energy efficient sources. If captured biogenic CO2 is considered a negative emission, then the WTE plant would achieve carbon neutrality even by operating only six months per year due to the high fraction of biogenic content in the fuel mixture.        

    The process model for CAP revealed extensive water utilization to avoid ammonia slip and thus additional energy requirements associated with cooling. The flue gas treatment characteristics at Sävenäs WTE plant corresponds well with the specifications for CAP but nonetheless the location of the WTE plant does not offer a natural source of cooling water with a preferable temperature of 5ºC. Hence, MEA was found to be the most viable option for Sävenäs WTE plant with a high technological readiness and seasonal operation already proven feasible at large pilot-scale plants.

  • 2.
    Chen, Xuanjing
    et al.
    College of Resources and Environment, Southwest University, Chongqing, PR China, Water Systems and Global Change Group, Wageningen University & Research, PB, Wageningen, the Netherlands.
    Strokal, Maryna
    Water Systems and Global Change Group, Wageningen University & Research, PB, Wageningen, the Netherlands.
    Kroeze, Carolien
    Water Systems and Global Change Group, Wageningen University & Research, Wageningen, the Netherlands.
    Ma, Lin
    Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, PR China.
    Shen, Zhenyao
    State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing, PR China.
    Wu, Jiechen
    Key Lab of Plant-Soil Interaction, MOE, Center for Resources, Environment and Food Security, College of Resources. Environmental Sciences, China Agricultural University, Beijing, PR China.
    Chen, Xinping
    College of Resources and Environment, Southwest University, Chongqing, PR China, Academy of Agricultural Sciences, Southwest University, Chongqing, PR China.
    Shi, Xiaojun
    College of Resources and Environment, Southwest University, Chongqing, PR China, Academy of Agricultural Sciences, Southwest University, Tiansheng Road 02, Chongqing 400715, PR China.
    Seasonality in river export of nitrogen: A modelling approach for the Yangtze River2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 671, p. 1282-1283Article in journal (Refereed)
    Abstract [en]

    In China, many estuaries suffer from eutrophication problems such as green tides and hypoxia. This is often a result of human activities on land leading to increased nutrient exports by rivers. River pollution shows seasonal trends that are not well understood. Therefore, the main objective of this study is to improve our understanding of the seasonal variation in river export of dissolved inorganic nitrogen (DIN) by source and at the sub-basin scale. To this end, we modified the existing MARINA model 1.0 (Model to Assess River Input of Nutrient to seAs) to account for seasonality in river export of DIN, and applied it to the Yangtze River. The resulting MARINA model version 1.1 takes a mass-balance approach and accounts for seasonality in human activities (e.g., crop planting and fertilization) and meteorology. The model distinguishes four seasons: winter (December–February), spring (March–May), summer (June–August) and fall (September–November). Our results for Yangtze indicate that N inputs to land and river export of DIN to sea are higher in summer and lower in winter. In spring, summer and fall, diffuse sources from agriculture contribute 43–85% to DIN export. In spring and fall, use of synthetic N fertilizers in cropland is an important source of DIN. In summer, both atmospheric N deposition and synthetic N fertilizers dominate. Animal manure is typically applied on land in spring and fall, contributing then to DIN. In winter, point sources of animal manure are responsible for 34–74% of DIN river export. In general, more DIN is exported to the sea from activities in middlestream and downstream sub-basins. Our results can serve as an example for other large rivers worldwide, and support the formulation of effective strategies to reduce seasonal eutrophication.

  • 3.
    Crampelle, Cecilia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Återbruk av möbler och inredning i studentbostadsområden2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Every year bulky waste is stashed outside and around the waste rooms that could be reused if taken care of properly. The European Union has set the waste hierarchy to lead the society in a direction towards a more sustainable consumption and waste management. This master thesis is based on the wastefulness of natural resources and the possibilities to take care of them. The interest of reuse of furniture and furnishings within a community based on students from Luleå University of Technology has been researched. This has resulted in a guide for implementation of a reuse event, which was tried out in April 2017.

     

    It seems that students have potential to reuse more than they normally do, which has been confirmed through questioners and a case study. Fifty percent of the participating students have obtained furniture or furnishings during the last 12 months and just a small part of them has disposed of something through reuse facilities or websites during the same period. The majority showed interest for used goods and the main reason for this was economics.

     

    To sum up, there is potential for reuse methods that involve students of LTU which could save nature not only a lot of CO2 emissions but also i.e. eutrophication, acidification, water and chemicals. Which would have a positive impact on the environment.

     

    If the reuse event, tested for this thesis, is implemented it is recommended to invite a larger target group and arrange it in a more public space.

  • 4.
    Grundström Mörtzell, Beatrice
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Riskbedömning av petroleumkolväten i mark och grundvatten vid Uddebo Oljehamn.2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Uddebo Oljehamn är en av sex hamndelar inom Luleå Hamns område och har sedan 1940-talet bedrivit miljöfarlig verksamhet. Idag har Uddebo Oljehamn två kajer där det årligen lastas och lossas cirka 360 000 ton flytande produkter av petroleum, bensen och stenkolstjära. Inom industriområdet arrenderas mark ut till olika verksamhetsutövare, dessa är för närvarande:Circle K, Flogas, Kemira, LKAB, Preem, Ragnsells, Stena samt ST1. Under åren har ett flertal marktekniska undersökningar genomförts i uppdrag av enskilda verksamhetsutövare, dock har en sammanställd bild av föroreningssituationen över hela industriområdet saknats.

    Huvudsyftet med denna studie var att, för Uddebo Oljehamn, utföra en förenklad riskklassning inom Naturvårdsverkets ramar, av jord och grundvatten. Metoden bestod främst av en litteraturstudie samt statistiska beräkningar av representativ halt. Materialet till litteraturstudien tillhandahölls från Luleå Hamn och aktiva verksamhetsutövare på området. Information har även samlats från Luleå kommuns stadsarkiv och miljö- och byggförvaltningens arkiv.

    I riskbedömningen delades området in i 13 delområden och halten petroleumkolväten bedömdes för respektive område utifrån generella riktvärden från Naturvårdsverket och Svenska Petroleum Institutet. Resultatet blev att hela området bedöms tillhöra riskklass 2. På området har mark och grundvatten ställvis kraftigt förorenats till den grad som innebär stor risk för människor och miljö. Med den genomsläppliga jordarten i området finns stor risk att föroreningarna sprids från källan via grundvattnet.

    En mindre del av studien var att undersöka riskminimerande materials förmåga att separera kolföreningar genom sorption. Vid Uddebo Oljehamn finns ett reningsverk som behandlar oljeförorenat avloppsvatten genom en filteranläggning med en filterbädd av sand och antracit. I laboratorium utfördes enstegs skaktest enligt den svenska standarden SS-EN 12457-2 med L/S kvot 10. Inkommande vatten till filteranläggningen skaktestades med materialen: antracit, sand, FloatAbsorb och järnbelagt torvpulver. Resultatet visade att halten kolföreningar i blankprovet var lågt. Blandningen av sand och antracit hade mest framgång i att reducera halten organiskt kol i vattnet. Torvmaterialen adderade halten organiskt kol och lämpade sig inte till denna typ av rening.

  • 5.
    Hou, Yong
    et al.
    College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China.
    Wei, Sha
    College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China.
    Ma, Wenqi
    College of Resources and Environmental Science, Hebei Agricultural University, Baoding 071001, PR China.
    Roelcke, Marco
    Institute of Geoecology, Technische Universität Braunschweig, Braunschweig 38106, Germany.
    Nieder, Rolf
    Institute of Geoecology, Technische Universität Braunschweig, Braunschweig 38106, Germany.
    Shi, Shengli
    College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China.
    Wu, Jiechen
    College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China.
    Zhang, Fusuo
    College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China.
    Changes in nitrogen and phosphorus flows and losses in agricultural systems of three megacities of China, 1990–20142018In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 139, p. 64-75Article in journal (Refereed)
    Abstract [en]

    Urban expansion is a crucial process altering nutrient cycles in agro-ecosystems, often accompanied by negative impacts on the environment. Quantitative analysis of nutrient flows in agricultural systems of megacities and their interactions with urbanization is still lacking. This study reports on changing patterns in inputs, outputs, losses and cycling of nitrogen (N) and phosphorus (P) in agricultural systems in three of China’s megacities–Beijing, Shanghai and Chongqing during 1990–2014, using the substance flow analysis method. Results show that changing patterns of nutrient flows varied among cities. With rising urbanization rate in Chongqing, nutrients were increasingly imported to agricultural systems to sustain food demand, which led to increased nutrient losses. An opposite trend occurred in Beijing and Shanghai with high urbanization levels (over 80%) since the early 2000s, resulting from a decline in cropland and livestock numbers, and stricter enforcement of environmental laws. Mineral fertilizers and livestock husbandry both contributed largely to ammonia emissions from agriculture. Losses of nutrients to water bodies in Beijing were sourced mainly from the livestock sector, while derived from overuse of mineral fertilizers in Chongqing, suggesting that priority management practices need to be designed differently among regions. Increased intensity of nutrient losses from agriculture was significantly correlated with increased mineral fertilizer input, livestock density and feed import and with reduced recycling ratio of manure. Integrated management for better use of nutrients in fertilizers, feed and manure are urgently required at regional scales. Our findings can serve as basis for policy decisions for sustainable agricultural systems in megacities.

  • 6.
    Krook-Riekkola, Anna
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Modelling ambitious climate targets and long-term strategies for Sweden – Describing the main the challenges: Presentation at The 5th Asian Energy Modelling Workshop Achieving a Sustainable 2050: Insights from Energy System Modelling2018Conference paper (Other academic)
    Abstract [en]

    The aim is to share insights from modeling net zero CO2-emission pathways for Sweden from an energy system analysis approach, both with respect to results (how to get to net zero) and to modeling needs (what to include and how to link models). Sweden is a European country rich in biomass and energy intensive industries, thus rich in energy resources but also with challenging freight transports and industries to decarbonize. The model results shows that an increased use of biomass residues and waste heat significantly increase the possibility to meet the targets. TIMES-Sweden, an energy system optimization model of the comprehensive Swedish energy system, was used to explore different low carbon and net zero emission pathways until 2030 and 2045. In order to do so, the model has (and currently is) being updated to include fossil free alternatives to all energy conversion and production processes within the model. When doing so we take a process-oriented approach, thus describe important energy intensive industries (e.g. pulp & paper, iron & steel and cement) in detail. The model is driven by the demand of energy intensive products and services (e.g. heating of single-houses, production of ton steel and person-km in cars). The demand projections were determined by soft-linking TIMES-Sweden with a national CGE model, in which we relied on multiple direction-specific connection points.

  • 7.
    Kumar, Rajesh
    et al.
    Department of Environmental Science, Sharda University, Greater Noida, India. Department of Environmental Science, School of Earth Science, Central University of Rajsthan, Ajmer, India.
    Kumar, Ramesh
    Department of Environmental Science, School of Earth Science, Central University of Rajsthan, Ajmer, India.
    Singh, Shaktiman
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Singh, Atar
    Department of Environmental Science, Sharda University, Greater Noida, India.
    Bhardwaj, Anshuman
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Chaudhary, Himanshu
    Department of Environmental Science, Sharda University, Greater Noida, India.
    Hydro-geochemical characteristics of glacial meltwater from Naradu Glacier catchment, Western Himalaya2019In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 78, no 24, article id 683Article in journal (Refereed)
    Abstract [en]

    The pattern of changing hydro-geochemical characteristics of water in Himalayan rivers is primarily controlled by sediment load from natural sources in higher altitudes and anthropogenic sources such as the burning of fossil fuels for domestic use, vehicular emissions, and wind transported industrial pollutants in the downstream region. The assessment of water quality is critical for the comparison of natural and anthropogenic sources in the downstream areas due to the dependence of the population on the glacial meltwater for freshwater supply. In the present study, we investigate the physical and ionic characteristics of glacial meltwater from Naradu Glacier catchment concerning the dominant weathering process. The freshwater samples were collected during the ablation period of 2016 and 2017 from specified locations. The physical parameters (pH, electrical conductivity, and temperature) were measured in the field while the analyses for concentrations of major cations (Ca2+, Mg2+, K+, Na+) and major anions (Cl−, SO42−, HCO3−, NO3−) were done in the laboratory. The anions (HCO3− > SO42− > Cl− > NO3−) and cations (Ca2+ > Mg2+ > Na+ > K+) concentrations were observed to have similar trends for both of the ablation period. The statistical analysis shows the predominance of geological weathering processes in the catchment as the controlling factor for the variation in concentration of different ionic species. The catchment was found to be rich in rocks with carbonate mineral making the Ca2+ and HCO3− the most dominant ions in the glacial meltwater.

  • 8.
    Mathanlal, Thasshwin
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Bhardwaj, Anshuman
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, María-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Self-Sustainable Monitoring Station for Extreme Environments (S3ME2): Design and validation2019In: 2018 Second International Conference on Green Computing and Internet of Things (ICGCIoT), IEEE, 2019, p. 240-245Conference paper (Refereed)
    Abstract [en]

    We describe the development of a robust, self-sustainable, versatile environmental monitoring station, the S3ME2, with a multitude of sensors capable of operating in extreme environments (from cold arid sub-arctic regions to hot deserts and high-altitude mountain terrains), providing realtime quality data of critical climate and geophysical parameters for a wide field of research such as pressure, surface and subsurface temperature and humidity, magnetic field and seismic activity. The dedicated communication modem utilizes IoT technology and can deliver this data from remote regions. The S3ME2 has been designed as a low-cost instrument to facilitate the production of multiple units. During the pilot phase, it has demonstrated continuous operability for up to 6 months, including survival during extremely cold, snowy, and low insolation, and low wind periods in the Sub-Arctic region. With its robust design, S3ME2 exploits the use of renewable sources of energy such as solar and wind power to power the system. The S3ME2 has also been designed from a modular point of view with commercial off the shelf components (COTS) and open source hardware, considering long term operability of the station. The sensor modules can be easily added, replaced, or upgraded such that a stable functioning of the system is guaranteed.

  • 9.
    Nigéus, Susanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Green liquor dregs-amended till to cover sulfidic mine waste2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The mining industry produces massive amounts of waste that without treatment and in contact with oxygen can result in acid rock drainage (ARD) and increased leaching of metals. In Sweden, the common way to manage the mine waste after closure is to apply a dry coverage on top of the waste deposition. The access to a suitable cover-material is however limited and can lead to extensive costs for the mining company. This creates a great driving force for alternative solutions, e.g. bentonite amendment to till. However, bentonite production is costly both economically and environmentally due to time- and resource- consuming production. Recycling of industrial residues as a cover material is another option. The recycling is beneficial for many parts, i.e. the industry producing the residue, the mining industry that will use the residue and the society in its strive for zero waste. An industrial residue that has potential to improve the sealing layer qualities of a local till is Green Liquor Dregs (GLD), a residue from pulp production in a paper mill. In this study 5 to 20 wt. % of GLD from two different paper mills, with varying total solid content (TSC) and particle size distributions (PSD), were mixed with three tills also with varying PSD and TSC. The objectives of the study were to investigate if GLD addition can improve a till so it can be used in a sealing layer, how the fines- and clay content in the tills affects the hydraulic conductivity (HC) and the water retention capacity (WRC) of the till-GLD mixtures, and how the initial water content will affect the HC in the different mixtures. The HC of the mixtures based most of the tills studied improved, but not enough to reach the required 10-8 m/s. Only the material based on a more clayey silty till had an HC below 10-8 m/s, even if it increased with the addition of GLD. The WRC, on the other hand, shows promising results, especially for 15 wt. % GLD addition. An increase in WRC is seen the more GLD is added. However, due to compaction difficulties more than 20 wt. % addition is not recommended. There is a difference in both HC and WRC between the mixtures based on the different tills, and a characterization of the till as a bulk material and its mixture with GLD is suggested before using it in mine remediation purposes. The HC of the till is affected by the content of fines and especially clay. The results from the WRC is more complicated and a mineralogical study on the GLD and the clay fraction of the tills is recommended. This study also shows that the initial water content of the materials rather than dry density has an impact on the HC of the mixtures. The initial water content determines the degree wet of optimum that in this and previous studies has shown to greatly affect the HC. A drier till and GLD leads to that more GLD should be added to the mixture when reaching for optimal HC. Even if the study did not result in low enough HC in most of the cases, the WRC shows promising results and is the most important parameter minimizing the oxygen diffusion to the mine waste. The greatest challenge when working with GLD is, however, its heterogeneity which makes it difficult to predict how it will behave in a sealing layer. Even though, the recycling of GLD in mine waste remediation should be strived for as it is beneficial for both the industry that provides the residue and the mining company. It is also a great profit for the environment as it minimizes the waste disposed and reduce use of natural resources.

  • 10.
    Qureshi, Asif
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Co-disposal of lignite fly ash and coal mine waste rock for neutralisation of AMDManuscript (preprint) (Other academic)
    Abstract [en]

    The WRs from a lignite producing coal field and FA produced from a power plant incinerating lignite from this field have been investigated in this study with objectives including the effect of WR particle size, co-disposal of FA (cover and mixture) and WRs on AMD and leachate quality and potential for secondary mineralisation using PHREEQC. The effect of particle size has been clearly observed where smaller particle sizes (2mm) produced low pH (~2) leachates with elevated concentrations of the sulphide related elements (such as Fe, SO42-, Al, Zn, Co, Cr, Cu, Mn and Ni) compared to 5mm (pH~3) and 10mm (pH~3.7) particles, indicating that sulphide oxidation has been pronounced in smaller particles. Co-disposal of FA as mixture readily provides acid buffering minerals, resulting in better pH (~3–6) and leachate quality from the beginning, except initial flush-out on the first rinse. However, acidity produced by secondary mineralisation contributes towards the acidification of the system, causing stabilisation of pH at around 4.5−5. In contrast, the pH of the leachates from the FA cover scenario gradually increases from strongly acidic (pH~2) to mildly acidic (WR1: pH~5 and WR2: pH~4) and circumneutral (WR3: pH~7) along with decrease in EC and elemental leaching. Gradually increasing pH can be attributed to the cover effect, which reduces oxygen ingress, thus sulphide oxidation, causing pH to elevate. Since pH~4–5 is sufficient for the secondary Fe- and Al-mineral precipitation, the FA cover performs very well to achieve that until the conclusion of the column leaching experiment. However, due to slower reactivity of the system, leaching in the beginning cannot restricted. The co-disposal of FA as cover and/or mixture possess potential for neutralisation of AMD and improving leachate quality significantly. However, both systems need to be up-scaled and investigated for AMD neutralisation, leachate quality, kinetic modelling and geotechnical properties.

  • 11.
    Qureshi, Asif
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Effects of the co-disposal of lignite fly ash and coal mine waste rocks on AMD and leachate qualityManuscript (preprint) (Other academic)
    Abstract [en]

    Lignite fly ash (FA) and waste rocks (WRs) were mixed in three different ratios (1:1, 1:3 and 1:5) and studied to compare the effects of adding FA on AMD generation from coal mining WRs, leachability of elements and the potential occurrence of secondary minerals. FA mixed with WRs showed significant differences in pH levels compared to previous research. The 1:1 mixture performed best of all the three mixtures in terms of pH and leachability of elements, mainly due to the higher proportion of FA in the mixture. The pH in the 1:1 mixtures varied between 3.3 – 5.1 compared to other mixtures (2.3­ – 3.5). Iron and SO42- leached considerably less from the 1:1 mixture compared to the others, indicating that the oxidation of sulphides was weaker in this mixture. Aluminium leached to a high degree from all mixtures, with concentrations varying from mg L-1–g L-1. The reason behind this increase is probably the addition of FA which, due to acidic conditions and the composition of the FA, increases the availability of Al. For the same reason, high concentrations of Mn and Zn were also measured. Geochemical modelling indicates that the 1:1 mixture performs better in terms of precipitation of Al3+ minerals, whereas Fe3+ minerals precipitated more in mixtures containing less FA. These results suggest that, with time, the pores could possibly be filled with these secondary minerals and sulphate salts (followed by a decrease in sulphide oxidation), improving the pore water pH and decreasing the leachability of elements. Since grain size plays a crucial role in the reactivity of sulphides, there is a risk that the results from the leaching tests may have been influenced by crushing and milling of the WR samples.

  • 12.
    Qureshi, Asif
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Quaid-e-Awam University of Engineering, Science and Technology, Nawabshah, Pakistan.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Effects of the co-disposal of lignite fly ash and coal mine waste rocks on AMD and leachate quality2019In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 26, no 4, p. 4104-4115Article in journal (Refereed)
    Abstract [en]

    Lignite fly ash (FA) and waste rocks (WRs) were mixed in three different ratios (1:1, 1:3 and 1:5) and studied to compare the effects of adding FA on acid mine drainage generation from coal mining WRs, leachability of elements and the potential occurrence of the secondary minerals. FA mixed with WRs showed significant differences in pH levels compared to previous research. The 1:1 mixture performed best of all the three mixtures in terms of pH and leachability of elements, mainly due to the higher proportion of FA in the mixture. The pH in the 1:1 mixtures varied between 3.3 and 5.1 compared to other mixtures (2.3–3.5). Iron and SO42− leached considerably less from the 1:1 mixture compared to the others, indicating that the oxidation of sulphides was weaker in this mixture. Aluminium leached to a high degree from all mixtures, with concentrations varying from mg L−1 to g L−1. The reason behind this increase is probably the addition of FA which, due to acidic conditions and the composition of the FA, increases the availability of Al. For the same reason, high concentrations of Mn and Zn were also measured. Geochemical modelling indicates that the 1:1 mixture performs better in terms of precipitation of Al3+ minerals, whereas Fe3+ minerals precipitated more in mixtures containing less FA. These results suggest that, with time, the pores could possibly be filled with these secondary minerals and sulphate salts (followed by a decrease in sulphide oxidation), improving the pore water pH and decreasing the leachability of elements. Since grain size plays a crucial role in the reactivity of sulphides, there is a risk that the results from the leaching tests may have been influenced by crushing and milling of the WR samples.

  • 13.
    Wu, Jiechen
    et al.
    KTH, Industriell ekologi.
    Brandt, Nils
    KTH, Industriell ekologi.
    Malmström, Maria E.
    KTH, Industriell ekologi.
    Climate change effects on nitrogen loading to urban lakes: The case of Råcksta Träsk, Stockholm, Sweden2013In: Proceedings of the 6th International Perspectives on Water Resources & the Environment, 2013Conference paper (Refereed)
    Abstract [en]

    Nutrient loads to aquatic recipients can be expected to change due to climate change. In this work, we focus on nitrogen loads to the lake Råcksta Träsk in Stockholm, Sweden as an example of an urban ecosystem. A substance flow model is developed to describe the sources and pathways of nitrogen at present. A feed-back table approach is applied to indicate potential climate change effects on nitrogen source strengths and processes in pathways, using existing regional climate change scenarios. The tentative results indicate that biological, hydrological, meteorological and biogeochemical effects and change in human behavior as response to climate change may lead to altered nitrogen flows through an urban catchment.

  • 14.
    Wu, Jiechen
    et al.
    KTH, Industriell ekologi.
    Franzén, Daniel
    KTH, Industriell ekologi.
    Malmström, Maria E.
    KTH, Industriell ekologi.
    Anthropogenic phosphorus flows under different scenarios for the city of Stockholm, Sweden2016In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 542, p. 1094-1105Article in journal (Refereed)
    Abstract [en]

    Today, concerns prevail about the unsustainable use of phosphorus and worldwide eutrophication, thus requiring efficient management of phosphorus flows. With increasing population and associated urban growth, urban management of phosphorus flows in the perspectives of recycling, eutrophication and total budget becomes increasingly important. This study mapped phosphorus flows for a reference year (2013) and a future year (2030) using different scenarios for the city of Stockholm, Sweden. The results indicated that the Swedish goal of recycling phosphorus from wastewater would cover the majority of the total phosphorus budget for Stockholm. However, in 2013, only 10% of phosphorus was recycled for agricultural use, around half of which was from sewage sludge and the other half from food waste. Almost 50% of total phosphorus was sent to landfill/mining waste capping with sewage sludge, for economic reasons and lack of market. Among the scenarios of upstream and downstream urban management options studied in combination with population growth, recovery of phosphorus from sewage sludge had the greatest potential to increase the fraction recycled to agriculture. However, only upstream measures, e.g. changed diet, were able to reduce the total phosphorus budget. Urban management of phosphorus flows based on the different perspectives of recycling, eutrophication or total budget was shown to potentially result in different preferred management actions and both upstream and downstream measures need to be considered. Moreover, management needs to pay attention to small but environmentally sensitive flows, particularly when setting city goals on phosphorus recycling by percentage in a large budget.

  • 15.
    Wu, Jiechen
    et al.
    KTH, Industriell ekologi.
    Franzén, Daniel
    KTH, Industriell ekologi.
    Malmström, Maria E.
    KTH, Industriell ekologi.
    Nutrient flows following changes in source strengths, land use and climate in an urban catchment, Råcksta Träsk in Stockholm, Sweden2016In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 338, p. 69-77Article in journal (Refereed)
    Abstract [en]

    Managing nutrient flows to urban lakes is one of the main challenges to environmental sustainability in cities. Considering that future urban and climate changes may increase the challenge of handling future eutrophication, prediction of future nutrient loadings to aquatic environments in urban catchments has become increasingly important. Based on a new, innovative, structured Substance Flow Analysis (SFA) approach, where a source model was coupled to a Generalised Watershed Loading Functions (GWLF) model, this study investigated nutrient (nitrogen and phosphorus) delivery from sources to a water recipient for an urban catchment, using the case of Racksta Trask in Stockholm, Sweden, as an example. Potential effects from future changes in atmospheric deposition, vehicle volume and land use and from climate change (temperature and precipitation) were examined by comparing model scenarios in two periods (2000-2009 and 2050-2059). Model results suggested that climate change may have a greater impact on nitrogen loading to Racksta Trask lake than increasing vehicle volume and land use change. In addition, the results suggested that nitrogen loading to the lake may increase taking into account all changes examined, despite the expected decrease in background atmospheric deposition of nitrogen. In contrast, a marginal impact was found for phosphorus loading to the lake under all scenarios examined, resulting in only a slight increase in the combined scenario. From a nutrient pathways perspective, the results suggested that major pathways of nutrient loadings to the lake may not be much affected under most future scenarios examined, although groundwater was found to be a potentially sensitive pathway of nitrogen transport in the climate scenario. The model results provided important information for managers who need to plan for future nutrient handling in urban catchments, and the coupled SFA-GWLF model was suggested to be worthy of further testing at other sites and conditions.

  • 16.
    Wu, Jiechen
    et al.
    KTH, Industriell ekologi.
    Malmström, Maria E.
    KTH, Industriell ekologi.
    Nutrient loadings from urban catchments under climate change scenarios: Case studies in Stockholm, Sweden2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 518-519, p. 393-406Article in journal (Refereed)
    Abstract [en]

    Anthropogenic nutrient emissions and associated eutrophication of urban lakes are a global problem. Future changes in temperature and precipitation may influence nutrient loadings in lake catchments. A coupling method, where the Generalized Watershed Loading Functions method was tested in combination with source quantification in a Substance Flow Analysis structure, was suggested to investigate diffuse nutrient sources and pathways and climate change effects on the loadings to streamflow in urban catchments. This method may, with an acceptable level of uncertainty, be applied to urban catchments for first-hand estimations of nutrient loadings in the projected future and to highlight the need for further study and monitoring. Five lake catchments in Stockholm, Sweden (Råcksta Träsk, Judarn, Trekanten, Långsjön and Laduviken) were employed as case studies and potential climate change effects were explored by comparing loading scenarios in two periods (2000-2009 and 2021-2030). For the selected cases, the dominant diffuse sources of nutrients to urban streamflow were found to be background atmospheric concentration and vehicular traffic. The major pathways of the nitrogen loading were suggested to be from both developed areas and natural areas in the control period, while phosphorus was indicated to be largely transported through surface runoff from natural areas. Furthermore, for nitrogen, a modest redistribution of loadings from surface runoff and stormwater between seasons and an increase in the annual loading were suggested for the projected future climate scenarios as compared to the control period. The model was, due to poor monitoring data availability, only able to set an upper limit to nutrient transport by groundwater both in the control period and the future scenarios. However, for nitrogen, groundwater appeared to be the pathway most sensitive to climate change, with a considerable increase and seasonal redistribution of loadings. For phosphorus, loadings by different pathways were apparently less sensitive to climate change.

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