| 1. |
- Spetea, Cornelia, 1968
(författare)
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Energy-efficient cultivation of marine microalgae for biomass production : Final rapport: Energimyndigheten P45907-1
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This project has demonstrated the principle of rotational cultivation of marine microalgae and that species adapted to cold climates can provide higher productivity during cold periods. By using marine species, and thus seawater instead of freshwater in cultivation, the environmental impact is reduced. Society faces major challenges to produce sufficient amounts of biomass for energy and material, and microalgae have a great potential to complement sources from forestry and agriculture. At Nordic latitudes year-round microalgae cultivation is debatable due to seasonal variations in productivity. Shall the same species be used throughout the year or shall seasonal-adapted species be used? The aims of the project were to identify suitable algal strains for a potential annual rotation model, where different strains are rotated during three cultivation seasons, and to further develop and optimize an energy-efficient cultivation process for the marine environment. To achieve these aims, a laboratory study was performed where two marine microalgal strains out of 167 were selected for intended cultivation at the west coast of Sweden. One strain belongs to the species Nannochloropsis granulata and the other to Skeletonema marinoi. The strains were cultivated in three simulated growth seasons: summer, winter and spring, and thereafter compared. We show that Nannochloropsis produced more biomass with more incorporated energy in lipids during summer and spring (25 MJ kg-1 compared to about 45 MJ kg-1 for diesel), whereas Skeletonema produced more biomass rich in carbohydrates and proteins during winter. Skeletonema was in general more efficient in taking up phosphate. Based on our results, biomass production as energy feedstock would be energy efficient only during the summer on the Swedish west coast. Nevertheless, species could be rotated for different purposes during the year. Biomass production could be combined with nutrient recycling of wastewater, for example, from fish industry. Our project faces a challenge in boosting the biomass produced in winter, but this could be solved, for example, by optimization of the cultivation medium and temperature increase with heat wastewater or other heat waste. The summer species Nannochloropsis proved to withstand winter by activating different lipid metabolic pathways than the cold-adapted species Skeletonema uses. Enhanced synthesis of proteins, such as enzymes, in Skeletonema during winter may compensate for their reduced activities, promoting growth and biomass production even at low temperatures. More species need to be studied to find those with higher productivity under winter conditions. In practice, the work-related consequences of a rotational cultivation should be weighed against its benefits, relative to a shorter cultivation season in each application. Potential applications mainly include cleaning of air and seawater, production of energy, biomass and biomaterials for the industry.
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| 2. |
- Gustafsson, Marcus, 1987-, et al.
(författare)
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Värdeskapande av koldioxid från biogasproduktion
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Koldioxid (CO₂) har en negativ påverkan på klimatet, men har även många praktiska användningsområden. Många industriella processer släpper ut CO₂ i höga koncentrationer som skulle kunna fångas in för att begränsa emissioner och samtidigt skapa värdefulla produkter. Ett exempel på en sådan process är biogasuppgradering – en separationsprocess av förnybara gaser, där metan tas till vara för användning som fordonsbränsle eller energibärare inom industri, medan CO₂ släpps ut i atmosfären. Syftet med detta projekt har varit att kartlägga möjligheter och tekniker för att tillvarata grön CO₂ från biogasproduktion, så kallad carbon capture and utilization (CCU), samt att utreda förutsättningar för att tillämpa dessa i en svensk kontext. Arbetet har vägletts av följande frågeställningar:Hur stor är den nuvarande och framtida potentialen för CCU från biogasproduktion?Vilka möjliga användningsområden finns det för CO₂ från biogasproduktion?Vilka faktorer påverkar valet av användningsområde för CO₂ från biogasproduktion?Hur stor är den miljömässiga nyttan av CCU från biogasproduktion?För att besvara dessa frågeställningar genomfördes potentialberäkningar, multikriterieanalys och livscykelanalys, med utgångspunkt i svensk biogasproduktion. En referensgrupp bestående av representanter för stora svenska företag inom biogasproduktion och teknik för biogasuppgradering användes för att möjliggöra samproduktion och nätverkande mellan forskargruppen och branschen.Produktionen av CO₂ från biogas uppskattades till 160 000 ton/år 2020, med potential att öka till 540 000 – 840 000 ton/år på medellång sikt och 790 000 – 1 230 000 ton/år på lång sikt, som en följd av en förmodad ökning av biogasproduktionen i Sverige. En stor del av koldioxiden produceras dock vid relativt små uppgraderingsanläggningar, vilket kan begränsa möjligheten att tillämpa CCU på grund av höga investerings- och driftskostnader. Att tillföra vätgas för att omvandla all CO₂ till metan skulle potentiellt kunna öka metanproduktionen från biogas från 2 till 3 TWh/år på kort sikt och från 11 till 17 TWh/år på lång sikt, förutsatt tillräckligt stor tillgång på vätgas.Andra sätt att använda CO₂ från biogas innefattar bland annat produktion av biomassa eller kemikalier, härdning av betong, pH-reglering av processvatten och användning som köldmedium. Valet av CCU- alternativ kan påverkas av miljömässiga, tekniska, ekonomiska och policyrelaterade aspekter. Ur biogasproducenternas perspektiv är metanisering det som är mest kompatibelt med det befintliga produktionssystemet och affärsmodellen, medan andra lösningar oftast innebär att en annan aktör tar hand om koldioxiden. Vätgas behövs för såväl metanisering som produktion av kemikalier. En annan begränsande faktor är höga renhetskrav på all CO₂ som distribueras och säljs på marknaden. Den geografiska spridningen på anläggningarna kan också vara en utmaning.Många CCU-alternativ kan förbättra biogasens miljöprestanda genom att ersätta fossilbaserade produkter. Klimatpåverkan blir lägst om koldioxiden metaniseras med förnybar vätgas eller mineraliseras i betong, men även andra former av miljöpåverkan kan minskas genom att tillämpa dessa eller andra CCU-alternativ. Som jämförelse kan permanent lagring av CO₂ i geologiska formationer (carbon capture and storage, CCS) endast minska klimatpåverkan, medan det ökar övriga typer av miljöpåverkan. Samtidigt kan permanent lagring av biogen CO₂ göra det svårare att minska användningen av fossil CO₂ och ställa om till ett mer hållbart samhälle. Behovet av kol i många viktiga processer och produkter talar för att biogen CO₂ bör användas och inte lagras.
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| 3. |
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| 4. |
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| 5. |
- Hermansson, Malte, 1954, et al.
(författare)
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Nitrifierande biofilmer för biologisk kväverening i avloppsreningsverk
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Biological nitrogen removal is implemented in Swedish wastewater treatment plants, often using biofilm processes for nitrification. Using DNA based methods we analyzed population dynamics and activity of nitrifying biofilms, and have tested different running strategies in a pilot plant with controlled ammonium concentrations.
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| 6. |
- Plaza, Elzbieta, et al.
(författare)
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Användning av Anammox för en förbättrad kväveavskiljning vid avloppsverk
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Man kan få stor energibesparing och minskad klimatpåverkan om deammonifikation kan användas för att avskilja kväve ur huvudströmmen vid kommunala avloppsreningsverk. Processen sker utan oxidation av organiskt material vilket ger möjlighet till ökad biogasproduktion.Deammonifikation består av biokemiska reaktioner i två steg: 1) partiell nitritation (då hälften av inkommande ammoniummängd oxideras till nitrit med hjälp av aeroba ammoniakoxiderande bakterier, AOB) och 2) anammox (då resten av ammonium och den bildade nitriten övergår till kvävgas med hjälp av anammoxbakterier). Syre behövs bara till steg 1, och ingen extern kolkälla behöver tillföras.I dag används deammonifikation för rening av varmt och kväverikt rejektvatten från slamavvattning, där det går att hålla hög hastighet på processen och undvika oxidation av nitrit till nitrat av nitritoxiderande bakterier (NOB). I reningsverkets huvudström med relativt kallt och kvävefattigt vatten är utmaningarna dels att behålla tillräcklig biomassa eftersom AOB och anammoxbakterier tillväxer långsamt, dels att undvika nitritoxidation av NOB som konkurrerar med AOB om syre.Forskare vid kth och chalmers har gjort pilotförsök vid Hammarby Sjöstadsverket i en reaktor på 200 l med biofilmsbärare (MBBR). Försöken drevs som en enstegsprocess med partiell nitritation och anammox i samma reaktor. Först studerades effekten av en gradvis sänkning av temperaturen från 19 till 10 °C, och därefter effekten av sänkt ammoniumhalt i inkommande avloppsvatten från 500 till 45 mg/l vid konstant låg temperatur (13 °C). Kväveföreningarnas koncentration mättes i inflöde och utflöde. Aktiviteten hos bakteriegrupperna mättes med tester av deras syreupptagning och kväveupptagning samt förmåga att bilda kvävgas. Den mikrobiella sammansättningen studerades.Resultaten visade att mellan 19 och 16 °C var kväveavskiljningen hög (> 70 procent). Vid 13 °C var kväveavskiljningen lägre (55 %) och vid 10 °C blev processen instabil med mycket låg avskiljningsgrad (
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| 7. |
- Wik, Torsten, 1968
(författare)
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Nitrifikation i biobädd - Adsorption av ammonium i pilotanläggningarna på Sjölundaverket
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For model based control and optimization of plants using nitrifying trickling filters, the fast dynamics of the filters have to be modeled. Experiments have been carried out on a pilot-scale trickling filter at Sjölunda WWTP in Malmö, and a model has been developed to analyze the dynamics. The experiments were: (i) a pulse response experiment for calibration of the model to the plant, (ii) an experiment with a step increase in influent ammonium concentration, (iii) a step decrease in influent ammonium concentration, and (iv) an experiment where dissolved potassium chloride was added to the influent during half an hour. The flow and the influent total concentration of dissolved nitrogen were constant during the experiments. Transient changes in the difference between influent and effluent total concentration of nitrogen, in all of the experiments, indicate adsorption of ammonium when the ammonium bulk concentration increases and desorption when it decreases. These phenomena affect the dynamics such that the transients in the effluent ammonium concentration are slower than they would be otherwise. Simulations of the model, where the amount of ammonium adsorbed is assumed proportional to the ammonium concentration in the biofilm, agree with measured effluent concentrations of ammonium, nitrite, nitrate and alkalinity. However, at high ammonium loads the model overestimates the effluent nitrate concentration and underestimates the effluent alkalinity. This can be explained by denitrification in anoxic regions of the biofilm, which is not considered in the present model. A comparison between the response to the increase and the response to the decrease in ammonium concentration show that the transients were significantly slower when the influent ammonium concentration was increased. In the experiment where potassium chloride was added, the effluent ammonium concentration increased during a period after the addition started and decreased during a period after the addition was terminated. This indicates that there is an ion-exchange between ammonium and potassium ions. However, the changes in effluent concentration were too small in comparison to the variations in the measurements to estimate the amount of ammonium adsorbed.
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| 8. |
- Alhelfi, Ali Kadhim Hadi, et al.
(författare)
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Assessing Learning in Higher Education
- 2012
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Rapport (populärvet., debatt m.m.)abstract
- Assessment is a key activity within the higher education system. From the student´s perspective, assessment shapes what is to be learned; from the perspective of the educator it gives clear inputs about the quality of learning. Thus, as defined by the term, ‘Constructive alignment’, by careful planning of the assessment strategy and wise selection of the assessment methods, the teaching-learning experience can be designed in an aligned manner towards the achievement of the learning outcomes. Although, defined in different ways, the basic purpose of assessment is to work as a feedback tool to both, students and teachers, to improve the student learning. In this work, we review and comment on theoretical aspects of assessment including its significance and characteristics. Moreover, some important considerations regarding the design of the assessment activities are presented, together with the description of some methods for assessing learning. With this work we would like to invite the reader to reevaluate the significance of assessment within the learning experience, and by this, hopefully the educator is “inspired” to improve the assessment activities in the classroom or another less conventional learning space.
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| 9. |
- Alvors, Per, et al.
(författare)
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Research and development challenges for Swedish biofuel actors – three illustrative examples : Improvement potential discussed in the context of Well-to-Tank analyses
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Currently biofuels have strong political support, both in the EU and Sweden. The EU has, for example, set a target for the use of renewable fuels in the transportation sector stating that all EU member states should use 10% renewable fuels for transport by 2020. Fulfilling this ambition will lead to an enormous market for biofuels during the coming decade. To avoid increasing production of biofuels based on agriculture crops that require considerable use of arable area, focus is now to move towards more advanced second generation (2G) biofuels that can be produced from biomass feedstocks associated with a more efficient land use.Climate benefits and greenhouse gas (GHG) balances are aspects often discussed in conjunction with sustainability and biofuels. The total GHG emissions associated with production and usage of biofuels depend on the entire fuel production chain, mainly the agriculture or forestry feedstock systems and the manufacturing process. To compare different biofuel production pathways it is essential to conduct an environmental assessment using the well-to-tank (WTT) analysis methodology.In Sweden the conditions for biomass production are favourable and we have promising second generation biofuels technologies that are currently in the demonstration phase. In this study we have chosen to focus on cellulose based ethanol, methane from gasification of solid wood as well as DME from gasification of black liquor, with the purpose of identifying research and development potentials that may result in improvements in the WTT emission values. The main objective of this study is thus to identify research and development challenges for Swedish biofuel actors based on literature studies as well as discussions with the the researchers themselves. We have also discussed improvement potentials for the agriculture and forestry part of the WTT chain. The aim of this study is to, in the context of WTT analyses, (i) increase knowledge about the complexity of biofuel production, (ii) identify and discuss improvement potentials, regarding energy efficiency and GHG emissions, for three biofuel production cases, as well as (iii) identify and discuss improvement potentials regarding biomass supply, including agriculture/forestry. The scope of the study is limited to discussing the technologies, system aspects and climate impacts associated with the production stage. Aspects such as the influence on biodiversity and other environmental and social parameters fall beyond the scope of this study.We find that improvement potentials for emissions reductions within the agriculture/forestry part of the WTT chain include changing the use of diesel to low-CO2-emitting fuels, changing to more fuel-efficient tractors, more efficient cultivation and manufacture of fertilizers (commercial nitrogen fertilizer can be produced in plants which have nitrous oxide gas cleaning) as well as improved fertilization strategies (more precise nitrogen application during the cropping season). Furthermore, the cultivation of annual feedstock crops could be avoided on land rich in carbon, such as peat soils and new agriculture systems could be introduced that lower the demand for ploughing and harrowing. Other options for improving the WTT emission values includes introducing new types of crops, such as wheat with higher content of starch or willow with a higher content of cellulose.From the case study on lignocellulosic ethanol we find that 2G ethanol, with co-production of biogas, electricity, heat and/or wood pellet, has a promising role to play in the development of sustainable biofuel production systems. Depending on available raw materials, heat sinks, demand for biogas as vehicle fuel and existing 1G ethanol plants suitable for integration, 2G ethanol production systems may be designed differently to optimize the economic conditions and maximize profitability. However, the complexity connected to the development of the most optimal production systems require improved knowledge and involvement of several actors from different competence areas, such as chemical and biochemical engineering, process design and integration and energy and environmental systems analysis, which may be a potential barrier.Three important results from the lignocellulosic ethanol study are: (i) the production systems could be far more complex and intelligently designed than previous studies show, (ii) the potential improvements consist of a large number of combinations of process integration options wich partly depends on specific local conditions, (iii) the environmental performance of individual systems may vary significantly due to systems design and local conditons.From the case study on gasification of solid biomass for the production of biomethane we find that one of the main advantages of this technology is its high efficiency in respect to converting biomass into fuels for transport. For future research we see a need for improvements within the gas up-grading section, including gas cleaning and gas conditioning, to obtain a more efficient process. A major challenge is to remove the tar before the methanation reaction.Three important results from the biomethane study are: (i) it is important not to crack the methane already produced in the syngas, which indicates a need for improved catalysts for selective tar cracking, (ii) there is a need for new gas separation techniques to facilitate the use of air oxidation agent instead of oxygen in the gasifier, and (iii) there is a need for testing the integrated process under realistic conditions, both at atmospheric and pressurized conditions.From the case study on black liquor gasification for the production of DME we find that the process has many advantages compared to other biofuel production options, such as the fact that black liquor is already partially processed and exists in a pumpable, liquid form, and that the process is pressurised and tightly integrated with the pulp mill, which enhances fuel production efficiency. However, to achieve commercial status, some challenges still remain, such as demonstrating that materials and plant equipment meet the high availability required when scaling up to industrial size in the pulp mill, and also proving that the plant can operate according to calculated heat and material balances. Three important results from the DME study are: (i) that modern chemical pulp mills, having a potential surplus of energy, could become important suppliers of renewable fuels for transport, (ii) there is a need to demonstrate that renewable DME/methanol will be proven to function in large scale, and (iii) there is still potential for technology improvements and enhanced energy integration.Although quantitative improvement potentials are given in the three biofuel production cases, it is not obvious how these potentials would affect WTT values, since the biofuel production processes are complex and changing one parameter impacts other parameters. The improvement potentials are therefore discussed qualitatively. From the entire study we have come to agree on the following common conclusions: (i) research and development in Sweden within the three studied 2G biofuel production technologies is extensive, (ii) in general, the processes, within the three cases, work well at pilot and demonstration scale and are now in a phase to be proven in large scale, (iii) there is still room for improvement although some processes have been known for decades, (iv) the biofuel production processes are complex and site specific and process improvements need to be seen and judged from a broad systems perspective (both within the production plant as well as in the entire well-to-tank perspective), and (v) the three studied biofuel production systems are complementary technologies. Futher, the process of conducting this study is worth mentioning as a result itself, i.e. that many different actors within the field have proven their ability and willingness to contribute to a common report, and that the cooperation climate was very positive and bodes well for possible future collaboration within the framework of the f3 center.Finally, judging from the political ambitions it is clear that the demand for renewable fuels will significantly increase during the coming decade. This will most likely result in opportunities for a range of biofuel options. The studied biofuel options all represent 2G biofuels and they can all be part of the solution to meet the increased renewable fuel demand.
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| 10. |
- Bergentall, Martina
(författare)
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Solid-state fermentation of side streams from Saccharina latissima
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The cultivation of brown macroalgae, such as Laminaria ssp. and Saccharina latissima, has increased extensively during the last decades; according to a report by Food and Agriculture Organisation of the United Nations1 , the cultivation of brown seaweeds exceeded 16 M tons worldwide as per 2019. At the Swedish West coast, the most cultivated brown alga is S. latissima – Sugar kelp – and it is mainly produced for food purposes. The S. latissima body consists of a blade, a stipe and a holdfast. The holdfast and stipe are stiff and tough and not useful for food in its raw state; instead, they become a side stream in the production. Fermentation of the stipes and holdfasts could be a way of improving their food properties, but the traditionally used and food-safe microorganisms employed for fermentation of soybeans, cereals, and other plant-based substrates are adapted to grow on plant carbohydrates such as starch and cellulose. This could be an obstacle when attempting to use algae as a substrate, since they are mainly constituted of other carbohydrates, such as alginate, laminarin, fucoidan and mannitol. For fungi to grow on algal biomass there should be a need for enzymes that can degrade the algal carbohydrates to release sugar units to be taken up by the fungal cells, but we did not find any reports on known food-safe fungi specialized on algae. Therefore, we wanted to test different pre-treatments, with the aim to make the algal carbohydrates accessible for established and safe fungi, traditionally used for fermentation of plant material, so that they would be able to ferment the algal biomass. Our project aimed at assessing the feasibility of using side streams (stipes and holdfasts) from S. latissima as a substrate for solid-state fermentation and to make initial total protein analyses of the product. The goal was to present a proof-of-concept – a model product – for future studies of e.g. amino acid composition, nutritional value, bioavailability, sensorics and environmental impact. The long-term impact target was to enable sustainable and profitable valorization of a presently unused side stream.
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