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  • 1.
    Dabrowski, Patrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Rening av rökgaskondensat i ett fjärrvärmeverk: Återanvändning av rökgaskondensat som spädvatten2017Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Arvika Fjärrvärme AB is manufacturing and distributing district heating to around 300 customers in Arvika. Heat production consists of a BFB boiler fed with GROT fuel (branches and peaks) and delivers a maximum power of 30 MW. In order to operate the plant, an average of 60 m3 of water per day is consumed from the urban water network. The water consumption is divided between water treatment, sooting and process cooling.

    In the processes, sulfur is dosed to obtain a more complete combustion of the hazardous flue gases that can occur. This is a result of previous thesis made for Arvika fjärrvärme. GROT is a fuel that contains high levels of moisture, which means that a high amount of condensate is formed during combustion, averaging 100 m3 per day. At present, condensate is sufficient to meet the condensate limit values ​​to be flushed into the drain. This is achieved by sand filtration and pH neutralization.

    Today, Arvika heat production is equipped with a purification stage for the feed water consisting of a softening filter and membrane filtration. This creates good conditions for cleaning the condensate and recirculating it in the process. Questions for this study are which hazardous substances the condensate can contain and how the condensate composition affected due to sulfur dosage. In addition, Arvika fjärrvärme wants to find out whether the purified condensate can replace the use of the urban water and, finally, if the condensate can be purified and used as feed water in the process.

    The execution of the work was based on a full-scale attempt in two operating cases of 9 and 18 MW. The tank collecting all condensate after purification in the sand filter and pH neutralization was coupled to the feed water purification stage. Thus, the condensate was pumped and purified in the softening filter and membrane filter. Assay substrates were collected before and after purification of the condensate.

    In addition to the topics that Arvika investigates, high levels of alkalinity were found in the condensate. The sulfur dosage that Arvika technology works with can be the cause of the high concentrations of sulphate. However, it appears that both the sulfate and alkalinity were purified in the membrane filter.

    The amount of condensate formed cannot completely replace the entire water requirement, but definitely large parts. The condensate can be used as feed water based on the retention rate for all substances. However, it appears that two substances, chloride and sulphate can create problems for the membrane filter. To investigate this, the condensate should be tested over a longer period of time to see the affect the chloride as well as the sulphate in the long run.

  • 2.
    Eros, Tibor
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology. Balaton Limnological Institute of the Hungarian Academy of Sciences, Hungary.
    Gustafsson, Pär
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Greenberg, Larry
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bergman, Eva
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Forest-Stream linkages: Effects of Terrestrial Invertebrate Input and Light on Diet and Growth of Brown Trout (Salmo trutta) in a Boreal Forest Stream2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 5, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Subsidies of energy and material from the riparian zone have large impacts on recipient stream habitats. Human-induced changes, such as deforestation, may profoundly affect these pathways. However, the strength of individual factors on stream ecosystems is poorly understood since the factors involved often interact in complex ways. We isolated two of these factors, manipulating the flux of terrestrial input and the intensity of light in a 2 x 2 factorial design, where we followed the growth and diet of two size-classes of brown trout (Salmo trutta) and the development of periphyton, grazer macroinvertebrates, terrestrial invertebrate inputs, and drift in twelve 20 m long enclosed stream reaches in a five-monthlong experiment in a boreal coniferous forest stream. We found that light intensity, which was artificially increased 2.5 times above ambient levels, had an effect on grazer density, but no detectable effect on chlorophyll a biomass. We also found a seasonal effect on the amount of drift and that the reduction of terrestrial prey input, accomplished by covering enclosures with transparent plastic, had a negative impact on the amount of terrestrial invertebrates in the drift. Further, trout growth was strongly seasonal and followed the same pattern as drift biomass, and the reduction of terrestrial prey input had a negative effect on trout growth. Diet analysis was consistent with growth differences, showing that trout in open enclosures consumed relatively more terrestrial prey in summer than trout living in covered enclosures. We also predicted ontogenetic differences in the diet and growth of old and young trout, where we expected old fish to be more affected by the terrestrial prey reduction, but we found little evidence of ontogenetic differences. Overall, our results showed that reduced terrestrial prey inputs, as would be expected from forest harvesting, shaped differences in the growth and diet of the top predator, brown trout.

  • 3.
    Harring, Niklas
    et al.
    Götebrogs universitet.
    Torbjörnsson, Tomas
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Educational Studies (from 2013).
    Lundholm, Cecilia
    Stockholms universitet.
    Solving Environmental Problems Together?: The Roles of Value Orientations and Trust in the State in Environmental Policy Support among Swedish Undergraduate Students2018In: Education Sciences, E-ISSN 2227-7102, Vol. 8, no 3, article id 124Article in journal (Refereed)
    Abstract [en]

    This paper explores whether value orientation (VO) and trust in the state (TIS) are linked to support for environmental intervention and steering among Swedish students in economics, law, and political science. Furthermore, we considered whether environmental personal norms mediate the link between VO and support for environmental policy instruments and finally, whether TIS moderates the link between environmental personal norms and support for environmental policy instruments, testing this on a sample of over 800 Swedish students. We found a positive link between both a self-transcendence VO and TIS on environmental policy support; however, we cannot confirm a moderating effect of TIS on the relation between environmental personal norms and policy support. Furthermore, left-wing students displayed stronger support for environmental intervention. We conclude that more knowledge on programme-specific characteristics regarding environmental values, beliefs, and attitudes among freshman students can enhance sustainability teaching intended to develop the students' critical and reflective capabilities.

  • 4.
    Hedelin, Beatrice
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Complexity is no excuse: Introduction of a research model for turning sustainable development from theory into practice2019In: Sustainability Science, ISSN 1862-4065, E-ISSN 1862-4057, Vol. 14, no 3, p. 733-749Article in journal (Refereed)
    Abstract [en]

    An overarching research model is introduced here that can support research for turning sustainable development (SD) from theory into practice. The model describes how existing and future theories, and empirical knowledge related to SD can be utilised to establish explicit linkages—steps—between fundamental SD principles and specific studied practices. The research model is intended to support planning, design and communication of a range of research endeavours such as individual studies, larger projects and research programmes. It internalises a number of insights from the current stock of SD literature such as explicitly linking local solutions to general SD principles, the need to embrace complexity and to use theory, the need for interdisciplinarity, and acknowledging SD as both substance and process. The model and its utilisation are explained and illustrated here by reference to a research example from river basin planning. The model is a critical and constructive attempt to establish structure and strategy in relation to the overwhelming complexity of the sustainability challenge—a challenge which urgently calls for reflective and effective research approaches.

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