Knowledge of the ultrastructural arrangement within wood fibres is important for understanding the mechanical properties of the fibres themselves, as well as for understanding and controlling the ultrastructural changes that occur during pulp processing. The object of this work was to explore the use of atomic force microscopy (AFM) in studies of the cell wall ultrastructure and to see how this structure is affected in the kraft pulp fibre line. This is done in order to eventually improve fibre properties for use in paper and other applications, such as composites. On the ultrastructural level of native spruce fibres (tracheids), it was found that cellulose fibril aggregates exist as agglomerates of individual cellulose microfibrils (with a width of 4 nm). Using AFM in combination with image processing, the average side length (assuming a square cross-section) for a cellulose fibril aggregate was found to be 15–16 nm although with a broad distribution. A concentric lamella structure (following the fibre curvature) within the secondary cell wall layer of native spruce fibres was confirmed. These concentric lamellae were formed of aligned cellulose fibril aggregates with a width of about 15 nm, i.e. of the order of a single cellulose fibril aggregate. It was further found that the cellulose fibril aggregates had a uniform size distribution across the fibre wall in the transverse direction. During the chemical processing of wood chips into kraft pulp fibres, a 25 % increase in cellulose fibril aggregate dimension was found, but no such cellulose fibril aggregate enlargement occurred during the low temperature delignification of wood into holocellulose fibres. The high temperature in the pulping process, over 100 ºC, was the most important factor for the cellulose fibril aggregate enlargement. Neither refining nor drying of kraft or holocellulose pulp changed the cellulose fibril aggregate dimensions. During kraft pulping, when lignin is removed, pores are formed in the fibre cell wall. These pores were uniformly distributed throughout the transverse direction of the wood cell wall. The lamellae consisting of both pores and matrix material (“pore and matrix lamella”) became wider and their numeral decreased after chemical pulping. In holocellulose pulp, no such changes were seen. Refining of kraft pulp increased the width of the pore and matrix lamellae in the outer parts of the fibre wall, but this was not seen in holocellulose. Upon drying of holocellulose, a small decrease in the width of the pore and matrix lamellae was seen, reflecting a probable hornification of the pulp. Refining of holocellulose pulp led to pore closure probably due to the enhanced mobility within the fibre wall. Enzymatic treatment using hemicellulases on xylan and glucomannan revealed that, during the hydrolysis of one type of hemicellulose, some of the other type was also dissolved, indicating that the two hemicelluloses were to some extent linked to each other in the structure. The enzymatic treatment also decreased the pore volume throughout the fibre wall in the transverse direction, indicating enzymatic accessibility to the entire fibre wall. The results presented in this thesis show that several changes in the fibre cell wall ultrastructure occur in the kraft pulp fibre line, although the effects of these ultrastructural changes on the fibre properties are not completely understood. / QC 20101012

The thesis is focussed on the performance of the fuel cell and the design of the cell for operation with natural gas and renewable fuels, e.g. biogas or gasified biomass. The performance is one of the important issues for the development and commercialisation of fuel cell stacks. In order to operate fuel cell on renewable fuels, without preceding reforming of the fuel, a high temperature fuel cell is needed, i.e. a solid oxide fuel cell (SOFC) or a molten carbonate fuel cell (MCFC). At present, the latter fuel cell type is much more mature when regarding the technical aspects than is the solid oxide fuel cell. The German company MTU has up to date installed about thirty MCFC plants, mainly in Europe and the USA but also in Japan. Moreover the European Commission has decided that the use of renewable fuels must increase at the expense of fossil fuels. This decision is one step towards a smaller dependence on fossil energy sources and limited emissions of greenhouse gases. The objective of this work is to better understand the factors that influence the cell performance: to determine the kinetic parameters of the hydrogen oxidation and the carbon monoxide oxidation and to get more information about the reaction mechanism, even when dealing with gases of low hydrogen content. The latter is of special importance when operating the cells on biogas or gasified biomass. These fuels also contain higher concentrations of carbon monoxide and carbon dioxide. It was found that the hydrogen mechanism proposed by Jewulski and Suski describes the anode performance even at lower concentrations of hydrogen, i.e. gases corresponding to gasified biomass. Furthermore, the carbon monoxide reaction will only slightly influence the anode performance but if the rate of the shift reaction is small the influence of direct oxidation of carbon monoxide will increase. Experimental investigations have shown that mass transfer limitations in the gas phase exist. By mathematical modelling it was found that the current collector has a larger affect on the concentration gradients than the porous electrode. The concentrations gradients in the current collector are caused by the shift reaction that mainly takes place at the electrode. However, if the gas corresponds to equilibrium at the current collector the profiles will become almost uniform. Furthermore the influence of wetting properties, the pore structure and pore size distribution have also been investigated in this thesis. The outcome of this thesis may be used for electrode development and design, as well as for input to reliable cell and stack models for system simulations. / QC 20101008

<p>Due to continuously stricter regulations regarding emissions from power generation processes, development of existing gas turbine combustors is essential. A promising alternative to conventional flame combustion in gas turbines is catalytic combustion, which can result in ultra low emission levels of NO_x, CO and unburned hydrocarbons. The work presented in this thesis concerns the development of methane oxidation catalysts for gas turbine combustors. The application of catalytic combustion to different combustor concepts is addressed in particular.</p><p>The first part of the thesis (Paper I) reports on catalyst development for fuel-lean methane combustion. The effect on catalytic activity of diluting the reaction mixture with water and carbon dioxide was studied in order to simulate a combustion process with exhaust gas recirculation. Palladium-based catalysts were found to exhibit the highest activity for methane oxidation under fuel-lean conditions. However, the catalytic activity was significantly decreased by adding water and CO₂, resulting in unacceptably high ignition temperatures of the fuel.</p><p>In the second part of this thesis (Paper II), the development of rhodium catalysts for fuel-rich methane combustion is addressed. The effect of water addition on the methane conversion and the product gas composition was studied. A significant influence of the support material and Rh loading on the catalytic behavior was found. The addition of water influenced both the low-temperature activity and the product gas composition.</p>

<p>The energy consumption is continuous to increase around the world and with that follows the demand for sustainable solutions for future energy systems. With growing energy consumption from fossil based fuels the threat of global warming through release of CO₂ to the atmosphere increases. The demand for cooling is also growing which would result in an increased consumption of electricity if the cooling demand was to be fulfilled by electrically driven cooling technology. A more sustainable solution can be to use heat-driven absorption cooling where waste heat may be used as driving energy instead of electricity.</p><p>This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO₂ emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield.</p><p>The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO₂ emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO₂ emissions can be lowered to 45 CO₂/MWhc by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study.</p><p>Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand.</p>

<p>This thesis encompasses CO₂ mitigation using three different processes: i) natural gas-fired combined cycle with chemical looping combustion (CLC), ii) trigeneration of electrical power, hydrogen and district heating with extended CLC, iii) steam-based gasification of biomass integrated in an advanced power cycle. </p><p>In CLC, a solid oxygen carrier circulates between two fluidised-bed reactors and transports oxygen from the combustion air to the fuel; thus, the fuel is not mixed with air and an inherent CO₂ separation occurs. In this thesis, CLC has been studied as an alternative process for CO₂ capture in a natural gas-fired combined cycle (NGCC). The potential efficiency of such a process using a turbine inlet temperature of 1200 °C and a pressure ratio of 13 is between 52 and 53 % when including the penalty for CO₂compression to 110 bar. It is shown that this efficiency cannot be further improved by including an additional CO₂ turbine. Two conceivable reactor designs for CLC in an NGCC are presented. Top-firing has been studied as an option to overcome a temperature limitation in the CLC reactor system. The degree of CO₂ capture is shown versus the temperature in the CLC reactor and its combustion efficiency. CLC has the potential to reach both a higher efficiency and a higher degree of CO₂capture than conventional post combustion CO₂ capture technique. However, further research is needed to solve technical problems as, for example, temperature limitations in the reactor to reach this potential. </p><p>Extended CLC (exCLC) is introduced, in which hydrogen is not only produced but also inherently purified. The potential efficiency of a novel tri-generation process for hydrogen, electricity and district heating using exCLC for CO₂capture is investigated. The results show that a thermal efficiency of about 54% might be achieved. </p><p>A novel power process named evaporative biomass air turbine (EvGT-BAT) for biomass feedstock is presented. This process contains a steam-based gasification of biomass, which is integrated in an externally fired gas turbine cycle with top-firing. In the EvGT-BAT process, the steam-based gasification is conducted in an entrained-flow tubular reactor that is installed in the SFC as a heat exchanger. The EvGT-BAT process has the potential to generate electrical power from biomass with an efficiency of 41 %.</p>

The aim of this project was to study and characterize the metabolitesof LGD-4033 in equine urine, with the final aim of using the results indoping controls in equestrian sports. Urine samples had been taken atdifferent points in time from three horses that had received thesubstance intravenously. The samples were both directly analysed usinga so called dilute-and-shoot approach and were also prepared with amixed mode anion exchange solid phase extraction. All analysis weredone with UHPLC-ESI-MS(/MS) in negative mode. A total of eightmetabolites were found, which were all combinations of phase Ihydroxylation and/or phase II glucuronidation. Of these a total of four(one that is both monohydroxylated and glucuronidated, one that isdihydroxylated, as well as two glucuronidated metabolites) would besuitable for doping control.

Due to continuously stricter regulations regarding emissions from power generation processes, development of existing gas turbine combustors is essential. A promising alternative to conventional flame combustion in gas turbines is catalytic combustion, which can result in ultra low emission levels of NOx, CO and unburned hydrocarbons. The work presented in this thesis concerns the development of methane oxidation catalysts for gas turbine combustors. The application of catalytic combustion to different combustor concepts is addressed in particular. The first part of the thesis (Paper I) reports on catalyst development for fuel-lean methane combustion. The effect on catalytic activity of diluting the reaction mixture with water and carbon dioxide was studied in order to simulate a combustion process with exhaust gas recirculation. Palladium-based catalysts were found to exhibit the highest activity for methane oxidation under fuel-lean conditions. However, the catalytic activity was significantly decreased by adding water and CO2, resulting in unacceptably high ignition temperatures of the fuel. In the second part of this thesis (Paper II), the development of rhodium catalysts for fuel-rich methane combustion is addressed. The effect of water addition on the methane conversion and the product gas composition was studied. A significant influence of the support material and Rh loading on the catalytic behavior was found. The addition of water influenced both the low-temperature activity and the product gas composition. / QC 20101126

The energy consumption is continuous to increase around the world and with that follows the demand for sustainable solutions for future energy systems. With growing energy consumption from fossil based fuels the threat of global warming through release of CO2 to the atmosphere increases. The demand for cooling is also growing which would result in an increased consumption of electricity if the cooling demand was to be fulfilled by electrically driven cooling technology. A more sustainable solution can be to use heat-driven absorption cooling where waste heat may be used as driving energy instead of electricity. This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO2 emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield. The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO2 emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO2 emissions can be lowered to 45 CO2/MWhc by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study. Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand. / QC 20101209

Avfallsminimering innebär att man genom olika typer av åtgärder minskar mängden avfall och halten av farliga ämnen i avfallet. Olika faktorer bidrar till uppkomsten av avfall men viktigast av alla är sambandet med den ekonomiska utvecklingen. Inom EU och i det svenska miljömålsarbetet har mål satts upp för att minska eller åtminstone inte öka avfallsmängderna. EU: s strategi för hållbar utveckling har målet att bryta sambandet mellan avfallsproduktion och ekonomisk tillväxt (s.k. frikoppling), och att kraftigt minska de totala mängder som genereras genom ökade insatser för att förebygga uppkomsten av avfall, effektivare användning av resurser och en övergång till mer hållbara konsumtionsmönster.    För att åstadkomma en frikoppling utgör avfallsminimering en av fem huvudsakliga prioriteringar inom EU:s s.k. avfallshierarki, som ligger till grund för EU:s avfallspolitik. Den innebär att avfall i idealfallet ska undvikas och det som inte kan undvikas skall återanvändas, eller återvinnas så långt som möjligt. Deponering ska undvikas så långt som möjligt då den är det sämsta lösningen enligt avfallsstrategin. Insatser mot avfallsminimering görs också för att undvika de negativa miljökonsekvenserna och spara på naturresurserna och bidra till en mer hållbar utveckling inför framtiden   Enligt strategin ska åtgärder och styrmedel bidra till en förskjutning uppåt i avfallshierarkin.  I EU:s ramdirektiv 2008/98/EG där avfallsminimering prioriteras, ska medlemsländerna ta fram ett nationellt program senast den 12 december 2013, för att förebygga avfall, där mål och möjliga åtgärder presenteras. Inom varje medlemsland har kommissionen utsett en nationell koordinator. Avfall Sverige är nationell koordinator och projektet samordnas även av Naturvårdsverket. I Sverige har regeringen formulerat 16 miljökvalitetsmål som närmare specificeras i 72 delmål. Avfall ryms under miljökvalitetsmålet ”En god bebyggd miljö” där det framgår att den totala mängden genererat avfall inte ska öka.   Förutom EU är de andra stora aktörerna som rapporten tar upp inom avfallsminimering Avfall Sverige, Naturvårdsverket, Håll Sverige Rent, Kommuner samt konsumenter. Olika åtgärder som bidrar till avfallsminimering är bl.a. effektivt utnyttjande av resurs för en förändring av våra konsumtionsmönster. Detta kan göras genom återanvändning, minskad kassation och spill av mat, forskning, ekonomiska styrmedel, miljöanpassad offentlig upphandling, och åtgärder för minskad reklam. Åtgärder riktade mot konsumenter idag summeras till informationsåtgärder, kampanjer m.m. som är ett långsiktigt mål mot avfallsminimering, genom bidrag till mer medvetna val och ändrade beteenden.   I Sverige strävar idag för ett ökat samarbete inom avfallsminimering genom t.ex. olika projekt och kampanjer som Sverige Minskar Avfallet. Återanvändning verkar vara huvudåtgärden för att tillmötesgå avfallsminimering inom landet.   Ett koordinerat samarbete mellan samtliga aktörer krävs för ett effektivare arbete mot avfallsminimering. Framgång kan nås genom ett genomtänkt val och kombination av styrmedel, ändrade beteende, samt ekonomiska syrmedel i form av skatter och moms som skapar incitament för konsumtion av miljövänligare produkter.   Många länder idag följer olika trender med avseende på avfallsminimering: att bryta sambandet mellan ökade avfallsmängder och BNP och involvering av andra aktörer utanför avfallssektorn med konsumenter och specifikt matavfall i fokus. Dock har endast Tyskland kunnat minska sin avfallsmängd gentemot BNP och problemet med avfall fortsätter att vara ett ouppklarat dilemma i andra länder.Sverige kan fortfarande göra mer insatser inom avfallsminimering. Enligt statstiken visar det sig att konsumenter inte gör tillräckligt med att minska avfallet. En jämförelse med andra länder visar även att kommuner kan erbjuda fler tjänster för att bidra till avfallsminimering och de utvalda relevanta forskningsbaserade styrmedlen kan tillämpas nationellt, istället för lokalt.   Många problemområden hindrar uppfyllandet av avfallsminimering såsom avfallsförbränning, Åtgärder för att minska energiförbrukning som olika isoleringstekniker och produktion av fordon som är energisnåla. Slutligen är konsumenters attityd och livsstil för att köpa nytt och slöseri en svår utmaning inom arbetet för avfallsminimering.   Om arbetet inom avfallsminimering blir mer fördjupat och samordnat mellan olika aktörer kan mycket mer göras inom området. För att minska avfallsmängderna och flytta fokus uppåt i avfallshierarkin, behövs andra starkare drivkrafter och styrmedel som kan utvecklas med hjälp av forskning. Tidsramen för styrmedlen är också viktig för att effekten kan lättare studeras och utvärderas.  Om dessa förändringar sker kommer Sverige att vara på god väg att uppfylla direktivet.

<p>Denna rapport är en del av examensarbetet i utbildningen Kemiteknik med inriktning mot miljökemi och bioteknik. Uppdraget har varit att dels utreda orsakerna bakom problematiken med att svavelväte uppstår vid neutralisering av sköljvatten hos Sapa Profiler AB samt vid lagring av slam på Eka Chemicals AB och att hitta förslag till åtgärder. Detta har främst gjorts genom experiment. Det som undersökts är om det är bakterier som orsakar problematiken i slammet, deras förmåga till anaerob och aerob tillväxt, möjlighet till nitratreduktion, hur vattenhalten påverkar deras förmåga att överleva i slammet, hur Enzym Clean påverkar dem, hur bakterierna reagerar på olika temperaturer, deras morfologi och gramegenskaper samt hur deras kolonier ser ut. Vattenhalt, sulfathalt samt glukonathalt i slammet har också undersökts. Undersökningarna har gjorts främst på slam från Brogårdsfabriken (Bro. 26/1) men även på slam från Vetlandafabriken (Vet. 26/1)</p><p>Under neutraliseringsprocessen är det en kemisk process som påverkas av pH och redoxpotential. Genom odling i SIM-agar har slutsatsen dragits att det är bakterier som orsakar problematiken med svavelväte i slammet. Bakterierna har förmågan att växa både aerobt och anaerobt, i det senare fallet reducerar de först nitrat innan de reducerar sulfat. Det har även kunnat visas att det är minst tre stammar bakterier med lite skiftande egenskaper vad gäller bland annat nitratreduktion som växer i slammen.</p><p>Slammet har en vattenhalt på cirka 75 %, sulfathalten som undersöktes genom spektrofotometrisk grumlighetsmätnig visade att sulfathalten i Brogårdsfabrikens slam 26/1 ligger på cirka 15 w% och i Vetlandafabrikens slam 26/1 var cirka 9 w/w%. Glukonathalten i Vetlandafabrikens slam 26/1 har bestämts till cirka 3 w/w%. En ökad mängd glukonat har visat sig leda till större bakteriell aktivitet. Då slammet hetats upp till 50°C eller över så har bakteriernas förmåga till överlevnad och tillväxt kraftigt begränsats. Det har dock inte kunnat visas på hur vattenhalten påverkar bakteriernas förmåga att överleva i slammet då detta försök inte gav några tillförlitliga resultat. Inte heller kunde några direkta slutsatser dras om hur Enzym Clean påverkar.</p><p>Slutsatsen är alltså att det är bakterier som orsakar problemen med uppkomsten av svavelväte i slammet efter en tids förvaring. Dessa lever både aerobt och anaerobt och det är när förhållandena blir anaeroba som de orsakar problem. Åtgärderna att sätta in är då att förhindra att slammet får stora anaeroba delar genom återkommande mekanisk bearbetning.</p><p> </p> / <p>This paper is a part of my education in Chemical engineering at School of Engineering, Jonkoping University. The tasks were to examine the reasons behind the origin of hydrogen sulphide at the neutralisation of process water at Sapa Profiler AB and during storage of the aluminium sludge at Eka Chemicals AB, and to find out the actions to take to prevent these problems. This has mainly been done by experiments. The things that have been examined is whether it is bacteria that cause the problems, their ability to grow aerobically and anaerobically, ability to nitrate reduction, how the water content affect their ability to survive in the sludge, how Enzym Clean affect them, how they react on different temperatures, their morphology, if they are gram positive or negative and what their colonies look like. Water, sulphur and gluconate content in the sludge have also been examined. The experiments are mainly performed on sludge from Brogårdsfabriken (Bro. 26/1) but also on sludge from Vetlandafabriken (Vet. 26/1).</p><p>The problem in the neutralisation process is caused by a chemical process affected by redoxpotential and pH. Through use of SIM-agar is the conclusion drawn that the problems with H₂S in the sludge are caused by bacteria. The bacteria have the ability to grow both aerobically and anaerobically and in the later case they use first nitrate and then sulphate as electron acceptor. It has also been shown that there are at least three strains of bacteria living in the sludge with a bit different features like their ability to reduce nitrate.</p><p>The sludge got water content of about 75 %. The sulphate content, which were examined spectrophotometerically, showed that the content in Bro. 26/1 is 15 w/w% and in Vet 26/1 is 9 w/w%. The gluconate content in Vet. 26/1 were determined by addition of Ce(IV) and titration with Fe(II) to about 3 w/w%. A higher gluconate content have been shown to increase the bacterial activity. It has been shown that when the sludge is heated to 50°C or higher the ability of the bacteria to survive in the sludge is dramatically lowered. But it haven't been able to determine how the water content affect the ability of the bacteria to survive in the sludge, the results were to unreliable. No conclusion could be drawn from the experiment with addition of Enzym Clean.</p><p>The conclusion is that it is bacteria that cause the problem of H₂S in the sludge. They grow both aerobically and anaerobically and the problems arise in the later case. The action to be taken is to hinder big areas of the sludge to become anaerobe, for example by turning the sludge mechanically.</p><p> </p>