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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Validation of mercury free methods for analysis of Chemical Oxygen Demand in municipial wastewater / Validering av kvicksilverfria analysmetoder för bestämning av kemiskt syreförbrukande ämnen (COD) i kommunalt avloppsvatten

Jonsson, Sandra January 2015 (has links)
Water is used every day in society and to be able to recycle this water we depend upon efficient wastewater treatment. It is vital to test the wastewater based on different parameters. One parameter is the Chemical Oxygen Demand (COD), which defines the amount of organic substances that can be chemically oxidized within the water. The Swedish standardized analytical method for COD (SS-028142), COD(Cr) is dependent on mercury, a substance which was banned according to Swedish regulations in year 2009 but is still used due to time limited dispensations. This report is a part of a pre-procurement innovative project initiated by the Swedish Water and Wastewater Association (SWWA) in order to bring forward and evaluate mercury free analytical methods for COD for municipal wastewater. The aim was to validate three analytical methods for COD: Chloride Determination, Chloride Elimination and PeCOD and compare the analytical results to the standardized COD(Cr). Three laboratories, Käppala (Stockholm), Gryaab (Gothenburg) and Komlab (Örnsköldsvik) were included in the validation process by providing analytical data. The validation was conducted using the data as input for the statistical methods regression, correlation and analysis of variance to investigate the performance of the individual methods. As a complement to the statistical results, comments regarding the methods brought up by the laboratory staff were compiled in order to reflect on the usability and robustness of the methods.  The results indicated that the method Chloride Determination was the method most similar to the COD(Cr) method, when investigating obtained COD concentrations, required analytical time and implementation steps needed to obtain a final COD value. This result was evident by high coefficient of determination values for influent wastewater samples. The PeCOD method, which was submitted in two versions, one manual and one automatic was only able to analyze soluble COD. It was found that the PeCOD methods obtained lower COD concentrations compared to the standardized method when analyzing filtered samples. Due to highly variable correlation coefficients between the PeCOD and COD(Cr) for various types of samples indicated that no uniform linear relation between the methods was present. Analysis with the Chloride Elimination method was halted early in the validation process, but was found to receive approximately 50 percent lower COD values than the reference method  COD(Cr). Finally it can be said that the input data for conducting the statistical test were limited and further analysis should be recommended in order to validate the results with a higher certainty. / Varje dag produceras avloppsvatten i samhället och för att kunna återanvända detta vatten krävs en tillförlitlig reningsprocess. För att rena avloppsvatten effektivt är det betydelsefullt att kontinuerligt testa avloppsvattnet utifrån ett antal viktiga parametrar. En av dessa är kemisk syreförbrukning, COD, som definieras av den mängd syre som förbrukas genom fullständig kemisk oxidation av organiskt material. Den svenska standardiserade analysmetoden för COD (SS-028142) , COD(Cr) är beroende av kvicksilver för att erhålla ett korrekt analysresultat utan påverkan av kloridjoner. Kvicksilver är enligt Svensk lag förbjudet sedan år 2009, men analysmetoden är dock vanligt använd på svenska avloppsreningsverk tack vare årliga dispenser. Detta examensarbete är en del av en förkommersiell innovationsupphandling som initierats av Svenskt Vatten med mål att undersöka och validera kvicksilverfria analysmetoder för COD tillgängliga på den internationella marknaden. Projektets syfte var att utföra en validering av tre analysmetoder: Klorid Determination, Klorid Elimination och PeCOD och jämföra dess resultat med referens metoden COD(Cr). Tre olika laboratorier, Käppala (Stockholm), Gryaab (Göteborg) och Komlab (Örnsköldsvik) medverkade i projektet. Valideringen genomfördes med de statistiska metoderna regression, korrelation och variansanalys, utifrån insamlade mätdata i syfte att undersöka de givna metodernas prestanda. Som ett komplement till det statistiska testerna sammanställdes synpunkter som framkommit under analysarbetet av laboratoriepersonal, för bedömning av metodernas användarvänlighet och robusthet.  Utifrån valideringen var det tydligt att metoden Klorid Determination hade störst likhet med COD(Cr) metoden utifrån givna analysresultat, analystid samt utförda analyssteg. Detta resultat styrktes av höga värden för determinationskoefficients för inkommande avloppsvatten mellan innovatios metoden och referense metoden COD(Cr). Analysmetoden PeCOD bestod av två olika versioner, skildrade den lösliga COD innehållet i provet istället för den total COD koncentrationen som hos COD(Cr). Oavsett vilken version av PeCOD som används erhålls ett lägre COD resultat jämfört med referens metoden COD(Cr) då filtrerade prover analyserades. De framtagna varierande korrelations koefficienter mellan PeCOD och COD(Cr) indikerade att ingen enhetlig korrelation gick att finna mellan metoderna hos de olika laboratorierna. Analysmetoden COD Elimination pausades tidigt i processen men de tidiga testerna visade på halverade COD koncentrationer jämfört med referens metoden.  Slutligen kan det nämnas att mätdata som användes som indata till de beskrivna statistiska testerna var begränsade och att vidare analyser rekommenderas för att kunna bevisa givna resultat med ökad sannolikhet.
2

Public procurement of cellulose-based and locally produced textiles - incentives and barriers for sustainable purchasing in the Swedish healthcare sector

JOHANNESSON, STINA January 2016 (has links)
Background: This study describes the incentives and barriers of public procurement ofcellulose-based and locally produced textiles in the Swedish healthcaresector governed by the county councils and regions. The size of the publicprocurement market is substantial which makes it imperative to analyse theprocurement decisions taken by this large customer from asustainability perspective. To understand these decisions better the publicprocurement is also analysed from an organisational perspective discussingpressures from global, regional and local stakeholders and governingauthorities.Methods: Empirical and primary data was collected from three semi-structuredinterviews with procurement officers, strategic buyers and heads ofprocurement departments in three county councils and regions in Sweden.The qualitative data was supplemented with quantitative data from a surveytargeting the additional 18 county councils and regions in Sweden. All 21county councils and regions in Sweden participated in or responded to theinterview and survey study. Six (33 %) complete responses were submitted,while five (28 %) surveys were partially responded to. Seven (39 %) countycouncils and regions did not participate in the study. The quantitative surveydata was analysed through the Fisher’s exact test and a thematic analysis wasapplied jointly on the interview and survey data due to the identicalinterview and survey questions.Results: The four themes found in the empirical data were concluded to be thedecision-making in these procurement processes being affected by manystakeholders, a high trust on suppliers for information updates andsustainable responsibility, an existing knowledge gap on cellulose-based andlocally produced textiles and the challenges and opportunities surroundingthe regulation of sustainability in the contract terms in the publicprocurement of textiles. The procurement officials being in a leading or nonleadingposition did not show any statistically significant effect on theperception of the clarity in the relevant political directives and how thisinfluences the possibility to take sustainable action in the procurementprocess, nor on whether the short-term (lowest) price has a higher prioritythan the long-term (e.g. long-term societal and environmental costs) in theprocurement of textiles.Conclusion: The sustainable public procurement of textiles within the Swedish healthcaresector governed by the county councils and regions is characterized by ahigh level of organisational complexity including many global, regional andlocal stakeholders. The governing authorities as well as the procuringorganizations and suppliers show interest in implementing sustainableprocurement processes which is however aggravated by static contract terms,limited knowledge on novel textile materials and the perceived costs relatedto the procurement.

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