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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.
51

Per- and Polyfluoroalkyl Substance (PFAS) Emissions from Recycling Processes of Lithium-Ion Batteries

Rensmo, Amanda January 2022 (has links)
The lithium-ion battery (LIB) recycling industry is currently under development to improve the yields for critical metals. However, the organic components of LIBs must also be handled, which may result in harmful chemical emissions as by-products. Of particular concern are highly persistent and mobile per- and polyfluoroalkyl substances (PFAS) that could be released during LIB recycling since some of these compounds have been linked with adverse health effects. In this work, an extensive literature review was conducted to determine the presence of fluorinated materials in state-of-the-art LIBs and the recycling conditions which could lead to the release of problematic PFAS. This information was used to develop a new analytical approach to capture the broadest range of organic and inorganic fluorine species in samples taken in different stages of the recycling process. This new method is based on a sequential extraction procedure using different solvents, followed by combustion ion chromatography (CIC) to quantify the potential emission of fluorine-containing chemicals of different polarities. The results show that organofluorine compounds are formed during recycling, particularly for the cathodes, indicating that PFAS might be present. For other samples, such as the NiMnCo salt product of recycling, only low fluorine levels were detected which implies almost complete removal. Future work should further outline the emission paths of these processes. This study highlights the necessity to further investigate the emissions related to fluorinated materials during LIB recycling and indicates that post-treatments or changes in conditions might be necessary to avoid the formation and emission of PFAS.
52

Assessment of Environmental Issues And Biodegradation Aspects of Current MSW Practices of Developing Country Metropolises - A Case Study of Bangalore

Shwetmala, * January 2016 (has links) (PDF)
Municipal solid waste (MSW) production has significantly increased in the rapidly urbanizing developing world and also changed composition with increased decomposable organic fraction in MSW (OFMSW) and plastics content. This has stressed the environment in many ways while city managers and citizens have responded with various technological and management solutions leading to a need for scientific, environmental, technological and sustainability assessments of the emerging problems. This sets the research agenda and framework for this study wherein the MSW generation, composition, processing and treatment methods, open dumping practices, environmental liability, natural degradation, sustainability issues etc. have been studied for the city of Bangalore as a model for such an emerging problem. Results show that MSW generation ranged from 0.1-0.4 kg/person/day and the OFMSW content was >80% emerging predominantly from fruit, vegetable and food wastes. About 10-15% of daily MSW generated appeared to be haphazardly dumped around the city in ~700 small to large dumps ranging from 10-6,500 m2 with potential for large GHG emissions. Their spread and characteristics were assessed for 3 consecutive years using a novel rapid survey method developed at IISc involving motorcycle borne student volunteer teams, GPS enabled locating, physical measurements and satellite image interpretations. Results indicated that dump sites were of three types, ephemeral small sized in the core area (303) functioning as transfer stations, medium sized ones in outer areas that were closed rapidly with construction debris and very soon inhabited with dwellings and the larger and longer duration dumps (2-3 years, 393) in the peripheral regions within 10 km from the city administrative boundary. This method was compared with physical measurement and satellite imaging and gave very high level of accuracy and is hence suggested for other cities as well. A smaller fraction of MSW is also dumped in open drains that lead to choking and flooding of 3 locations and this was studied with some detail. The environmental footprint of such dumps were assessed by theoretical and experimental on-site and off-site approaches and experimental results show low GHG (CH4) emissions and emission factors that was largely attributable to the shallow depth of dumps (~0.7 m) and its low pH. The decomposition rates were experimentally determined for open dump sites and drivers for decomposition monitored. By providing differential access to macro-fauna, meso-micro organisms and only soil contact in field scale experiments it was determined that the greatest loss in weight occurred primarily due to the rapid drying process that brings down decomposition within 6 days. During the early stages of decomposition, mostly micro with meso organisms are responsible and after 6 days, the moisture content falls below 60% making microbiological decomposition difficult and enabling other foraging organisms to take over. The weight loss (decay) could be patterned both on exponential decay or a two component fit representing a rapid initial decay followed by a slower long term decay process similar to soil application of organic matter. Monitoring the decentralized MSWM practices in the city suggests that small scale composting and biomethanation is gaining acceptance and is the possible direction for OFMSW in growing cities.
53

Värdeskapande av koldioxid frånbiogasproduktion : En kartläggning över lämpliga CCU-tekniker för implementeringpå biogasanläggningar i Sverige / Value creation of carbon dioxide from biogas production : A survey of suitable CCU techniques for implementation at biogasplants in Sweden

Broman, Nils January 2020 (has links)
Carbon dioxide from biogas production is currently considered to be without value and isbecause of this released into the atmosphere in the biogas upgrading process. The residualgas is a potential carbon source and can create value in the biogas manufacturing process.By finding a suitable value-creating process that utilizes carbon dioxide, it can be possibleto provide both economic and environmental incentives for companies to develop theiroperations. This project explored the possibility to create value from this CO2. Through anevaluation of the technical maturity of CCU technologies, a recommendation could be givenat the end of the project. An analysis of technical barriers, such as pollutants in the gas, aswell as barriers in the form of competence and corporate culture were examined in orderto provide a reasoned recommendation. The project mapped which value-creating systemswould be suitable for biogas producers in a Swedish context. This included established methaneand carbon dioxide upgrading techniques currently in use and suitable CCU techniquesthat can interact with the selected upgrading processes and serve as value creators. Based onthis survey, it was then possible to identify common, critical variables for these systems. Thereafter,a recommendation of an appropriate CCU technology could be given depending onthe CO2 composition produced. One conclusion from the study was that carbon dioxide concentrationsfrom the residual gas was often high (approx. 97-98 %) and did not contain anycorrosive or toxic components, and that this largely depends on how the digestion reactor ishandled in the production process. Thus, questions were raised about what the actual limitationsof the CCU are, as they did not seem to be technical. CCU techniques that proved to beof particular interest were pH regulation of sewage plants, CO2 as a nutrient substrate for thecultivation of microalgae, and manufacturing of dry-ice for refrigerated transports. All of thesetechnologies currently have a sufficiently high degree of technical maturity to be installedalready today. Other CCU techniques, such as "’Power to gas”, require a high CO2 concentrationand were discarded as the literature review did not suggest the economic potential forthem as they require additional CO2 upgrading steps. Instead, CCU techniques were chosenthat could be implemented directly with the existing CO2 quality. Furthermore, it was concludedthat one reason why CCU technologies have not been widely implemented is internalbarriers between distributors and manufacturers (or users) of CCU technologies. Thus, theuse of carbon dioxide from biogas production and implementation of CCU technologies canbe promoted by eliminating barriers in companies, such as a lack of both knowledge andfinancial incentives. / Koldioxid från biogasproduktion betraktas i dagsläget som utan värde och släpps ut i atmosfärenvid uppgradering av biogas. Restgasen är en potentiell kolkälla och kan vara värdeskapandeför biogasprocessen. Genom att finna en lämplig värdeskapande process som utnyttjarkoldioxid går det att ge både ekonomiska och miljömässiga incitament till företag att utvecklasin verksamhet. I detta projekt undersöktes möjligheten att skapa värde av denna CO2.Genom en utvärdering av den tekniska mognadsgraden hos CCU-tekniker kunde en rekommendationges vid projektets slut. En analys av tekniska hinder, såsom föroreningar i gassammansättningen,såväl som hinder i form av kompetens och företagskultur undersöktes för attkunna ge en motiverad rekommendation. I projektet kartlades vilka värdeskapande systemsom skulle passa för biogasproducenter i en svensk kontext. Detta inkluderade etableradeuppgraderingstekniker för metan- och koldioxid som används i dagsläget. I projektet undersöktesäven lämpliga CCU-tekniker som kan samverka med de valda uppgraderingsprocessernaoch och agera värdeskapande. Utifrån denna kartläggning kunde det sedan anges vilkagemensamma, kritiska variabler som finns för dessa system. Därefter kunde en rekommendationav lämplig CCU-teknik ges beroende på den producerade CO2 sammansättningen. Enslutsats i projektet var att koldioxid från restgasen ofta var av hög koncentration (ca. 97-98 %)och ej innehöll några korrosiva eller toxiska komponenter, och att detta till stor del beror påhur rötkammaren är hanterad i produktionsprocessen. Således väcktes frågor kring vilka defaktiska begränsningarna för CCU är, då de inte torde vara tekniska. CCU-tekniker som visadesig vara av särskilt intresse var pH-reglering av avloppsverk, CO2 som näringssubstratför odling av mikroalger, samt tillverkning av kolsyreis för kyltransporter. Samtliga dessatekniker har tillräckligt hög teknisk mognadsgrad för att kunna installeras i dagsläget. AndraCCU-tekniker, såsom ”Power to gas”, kräver en hög CO2-koncentration och avfärdades dålitteraturstudien inte talade för den ekonomiska potentialen i dessa eftersom de kräver ytterligareuppgraderingssteg för CO2. Således valdes istället CCU-tekniker som skulle gå attimplementera direkt med den befintliga CO2 kvalitén. Vidare drogs slutsatsen att en anledningtill att CCU-tekniker inte har blivit vida implementerade till stor del är interna hindermellan distributörer och tillverkare (eller utnyttjare) av CCU-tekniker. Således kan användandetav koldioxid från biogasproduktion och implementering av CCU-tekniker främjasgenom att eliminera hinder hos företag. I projektet yttrade sig detta som bristande ekonomiskaincitament och okunskap. Ett ökat användande av CCU-tekniker kan också uppnås genomatt införa lagar och regler som begränsar användandet av föråldrade tekniker som drivs avfossila bränslen, och som kan ersättas av klimatvänliga CCU-tekniker.
54

Reptilförekomster och kopplingar till miljöfaktorer på Billingen : Inventering av reptilfauna med artificial cover objects på lokal nivå i Västsverige / Reptile occurences and connections to environmental factors on Billingen : Survey of reptile fauna with artificial cover objects on a local scale in Western Sweden

Carlquist Segell, Maja January 2021 (has links)
Förlust av biologisk mångfald är den planetära gräns som överskrids mest, och medför bland de största hoten mot biosfärens integritet. Reptiler är funktionella delar i ekosystem, men habitatförlust, förändrad markanvändning och klimatförändringar orsakar globala populationsminskningar. Ekologisk övervakning möjliggör förståelse för arters tillstånd, och utveckling av bevarandeåtgärder. Denna förekomststudie syftar till att undersöka lokal reptilfauna, som inventerades med artificial cover objects (ACO) i två naturområden på Billingen, ett av de västsvenska platåbergen, i Skövde kommun 2021. Data från miljöbeskrivning och inventering samt över väderförhållanden samlades in, och samband mellan observationer och miljöfaktorer testades med statistiskt t-test för positiva skillnader mellan datagrupper. Skogsödla (Zootoca vivipara), kopparödla (Anguis fragilis), snok (Natrix natrix) och huggorm (Vipera berus),alla allmänna reptilarter i regionen, observerades i undersökningsområdet. Nio observationer gjordes under 20 regnfria dagar i juni och juli, med temperaturer över 18°C. Biotopkvaliteterna brynmiljöer och nektarresurser, solexponering och de öppna biotoperna beteshage och elledningsgata, förekom i signifikant högre utsträckning där observationer gjordes, än på platser utan observationer. Markfuktighet, mänsklig närvaro, naturvärden och områdesskydd uppvisade ingen signifikans. Resultaten överensstämmer med andra studier om reptilarternas habitat, och kan ses gälla på lokal nivå trots ett relativt litet dataunderlag. Effektiva reptilbevarande åtgärder i närområdet kan innebära upprätthållande och skapande av ytor med hög solinstrålning och strukturell komplexitet, fortsatt men inte utökat lågintensivt naturbete, samt ökad halt avträdslagsblandning och brynmiljöer i produktionsskog. Kunskapen kring reptilers ekologi, samtövervakningen av populationer, behöver utökas. Det rekommenderas vidare studier om reptiler, deras habitat och bevarande av biologisk mångfald på lokala nivåer. / Biodiversity loss is the most exceeded planetary boundary, and entails some of the largest threats against biosphere integrity. Reptiles are functional parts of ecosystems, but habitat loss and changes in land use and climate are causing global population declines. Ecological monitoring enables understanding of species’ conditions, and development of conservation measures. This occurrence study aims to investigate local reptile fauna, surveyed using artificial cover objects (ACOs), in two areas on Billingen, one of Western Sweden’s table mountains, in Skövde municipality 2021. Environmental, survey and weather data were collected, and relations between observations and environmental factors were tested with statistical t-test for positive differences between data groups. Zootoca vivipara, Anguis fragilis, Natrix natrix and Vipera berus, all regionally common reptile species, were observed in the investigated area. Nine observationswere made during 20 rain-free days in June and July, with temperatures above 18°C. Solarexposure, biotope qualities Forest edges and Nectar resources, and the open biotopes Pasture and Powerline corridor, occurred in significantly higher extent where observations were made, than on sites without observations. Soil moisture, Human presence, Natural values and Environmental protection did not exhibit any significance. The results correspond to other studies on the reptilespecies’ habitat, and may apply on a local scale despite a relatively small data amount. Effective conservation measures for local reptiles can imply maintaining and creating spaces with high solar radiation and structural complexity, continued but not extended low-intensity grazing, and increasing tree species mixture and edge zones in production forests. Knowledge on reptile ecology and population monitoring needs to increase. Further studies on reptiles and biodiversity conservation on local scales are recommended.
55

The Biowall Field Test Analysis and Optimization

Jacob J. Torres (5930906) 14 May 2019 (has links)
<div> <p>A residential botanical air filtration system (Biowall) to investigate the potential for using phytoremediation to remove contaminants from indoor air was developed. A full scale and functioning prototype was installed in a residence located in West Lafayette, Indiana. The prototype was integrated into the central Heating, Ventilating, and Air Conditioning (HVAC) system of the home. This research evaluated the Biowall operation to further its potential as an energy efficient and sustainable residential air filtration system.<br></p> <p> </p> <p>The main research effort began after the Biowall was installed in the residence. A field evaluation, which involved a series of measurements and data analysis, was conducted to identify treatments to improve Biowall performance. The study was conducted for approximately one year (Spring 2017-Spring 2018). Based on the initial data set, prioritization of systems in need of improvement was identified and changes were imposed. Following a post-treatment testing period, a comparison between the initial and final performances was completed with conclusions based on this comparison. </p> <p> </p> <p>The engineering and analysis reported in this document focus on the air flow path through the Biowall, plant growth, and the irrigation system. The conclusions provide an extensive evaluation of the design, operation, and function of the Biowall subsystems under review.</p> </div> <br>

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