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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.
61

Estudo da influência de argilas organofílicas no processo de biodegradação de nanocompósitos de PLA e seus efeitos genotóxicos e mutagênicos / Study of influence of organoclays on biodegradation process of PLA nanocomposites and its genotoxic and mutagenic effects

Souza, Patrícia Moraes Sinohara, 1988- 22 August 2018 (has links)
Orientadores: Ana Rita Morales, Maria Aparecida Marin-Morales / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T13:30:08Z (GMT). No. of bitstreams: 1 Souza_PatriciaMoraesSinohara_M.pdf: 5897831 bytes, checksum: ff702db4dd4540ec41606b5fd8a007e3 (MD5) Previous issue date: 2013 / Resumo: Neste estudo, foram preparados nanocompósitos de PLA e argilas organofílicas Cloisite 20A e Cloisite 30B, pelo método de intercalação do fundido. Os materiais foram caracterizados mediante Difração de Raios-X (DRX), Microscopia Eletrônica de Transmissão (MET), Análise Termogravimétrica (TGA) e Calorimetria Diferencial Exploratória (DSC). A influência das argilas organofílicas no processo de biodegradação do PLA foi avaliada pela quantificação da taxa de mineralização do PLA e dos nanocompósitos pela norma ISO 14855-2, em condições simuladas de compostagem. Também foi avaliada a influência das argilas no processo de degradação hidrolítica do PLA, pela análise visual e monitoramento de peso molecular após os períodos de 15 e 30 dias de degradação em composto. Diante da falta de informação relacionada à ecotoxicidade de polímeros biodegradáveis, a avaliação de efeitos citotóxicos, genotóxicos e mutagênicos do composto orgânico após a degradação dos materiais foi realizada empregando o bioensaio com o organismo teste Allium cepa. Os nanocompósitos preparados apresentaram estrutura intercalada, evidenciada pela análise de DRX. As micrografias obtidas por MET permitiram a observação de diferentes níveis de dispersão, incluindo regiões esfoliadas. Foram verificadas, após a incorporação das argilas organofílicas, a redução da estabilidade térmica e o aumento do grau de cristalinidade do PLA, pelas análises de TGA e DSC, respectivamente. Com relação às medidas de mineralização, notou-se que a argila Cloisite 20A não apresentou influência significativa na biodegradação do PLA. Por outro lado, a argila Cloisite 30B levou à redução dos valores de mineralização comparados com o polímero puro, o que pode estar relacionado à atividade antimicrobiana de seu agente modificador. Na avaliação da degradação hidrolítica, notou-se que a presença de argilas organofílicas pode diminuir a taxa de degradação, possivelmente pela atuação de suas camadas como barreira. Ainda assim, mesmo no caso dos nanocompósitos, a redução do peso molecular foi significativa indicando que o processo de compostagem é favorável para a cisão de cadeia do polímero nos materiais em estudo. Na análise realizada por meio do bioensaio com o organismo teste Allium cepa, foi verificado que, após a degradação do PLA e dos nanocompósitos, o composto orgânico apresentou redução do índice mitótico e aumento da indução das alterações cromossômicas, de forma estatisticamente significativa em relação ao controle negativo do ensaio (água destilada). Pela comparação dos resultados obtidos para os nanocompósitos em relação ao polímero puro, não foram verificadas diferenças estatisticamente significativas. Os tipos de aberrações cromossômicas observadas indicam um efeito genotóxico dos materiais, possivelmente relacionado a uma ação aneugênica dos produtos de degradação do PLA / Resumo: Neste estudo, foram preparados nanocompósitos de PLA e argilas organofílicas Cloisite 20A e Cloisite 30B, pelo método de intercalação do fundido. Os materiais foram caracterizados mediante Difração de Raios-X (DRX), Microscopia Eletrônica de Transmissão (MET), Análise Termogravimétrica (TGA) e Calorimetria Diferencial Exploratória (DSC). A influência das argilas organofílicas no processo de biodegradação do PLA foi avaliada pela quantificação da taxa de mineralização do PLA e dos nanocompósitos pela norma ISO 14855-2, em condições simuladas de compostagem. Também foi avaliada a influência das argilas no processo de degradação hidrolítica do PLA, pela análise visual e monitoramento de peso molecular após os períodos de 15 e 30 dias de degradação em composto. Diante da falta de informação relacionada à ecotoxicidade de polímeros biodegradáveis, a avaliação de efeitos citotóxicos, genotóxicos e mutagênicos do composto orgânico após a degradação dos materiais foi realizada empregando o bioensaio com o organismo teste Allium cepa. Os nanocompósitos preparados apresentaram estrutura intercalada, evidenciada pela análise de DRX. As micrografias obtidas por MET permitiram a observação de diferentes níveis de dispersão, incluindo regiões esfoliadas. Foram verificadas, após a incorporação das argilas organofílicas, a redução da estabilidade térmica e o aumento do grau de cristalinidade do PLA, pelas análises de TGA e DSC, respectivamente. Com relação às medidas de mineralização, notou-se que a argila Cloisite 20A não apresentou influência significativa na biodegradação do PLA. Por outro lado, a argila Cloisite 30B levou à redução dos valores de mineralização comparados com o polímero puro, o que pode estar relacionado à atividade antimicrobiana de seu agente modificador. Na avaliação da degradação hidrolítica, notou-se que a presença de argilas organofílicas pode diminuir a taxa de degradação, possivelmente pela atuação de suas camadas como barreira. Ainda assim, mesmo no caso dos nanocompósitos, a redução do peso molecular foi significativa indicando que o processo de compostagem é favorável para a cisão de cadeia do polímero nos materiais em estudo. Na análise realizada por meio do bioensaio com o organismo teste Allium cepa, foi verificado que, após a degradação do PLA e dos nanocompósitos, o composto orgânico apresentou redução do índice mitótico e aumento da indução das alterações cromossômicas, de forma estatisticamente significativa em relação ao controle negativo do ensaio (água destilada). Pela comparação dos resultados obtidos para os nanocompósitos em relação ao polímero puro, não foram verificadas diferenças estatisticamente significativas. Os tipos de aberrações cromossômicas observadas indicam um efeito genotóxico dos materiais, possivelmente relacionado a uma ação aneugênica dos produtos de degradação do PLA / Abstract: In this study, nanocomposites of PLA with organoclays Cloisite 20A and Cloisite 30B were prepared by the melt intercalation method. The materials were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). The influence of organoclays in the biodegradation process of PLA was assessed by quantifying the rate of mineralization according to ISO 14855-2, in simulated composting conditions. The influence of clays on the hydrolytic degradation process of PLA was also investigated by visual analysis and monitoring of molecular weight after periods of 15 and 30 days of degradation in organic compost. Given the lack of information related to ecotoxicity of biodegradable polymers, the assessment of citotoxic, genotoxic and mutagenic effects of the organic compost, after the materials degradation, was carried out using the bioassay with Allium cepa as test organism. The nanocomposites presented an intercalated structure, evidenced by XRD analysis. The TEM micrographs allowed the observation of different dispersion levels, including exfoliated regions. After incorporation of organoclays, a reduction of thermal stability and an increasing in the degree of crystallinity of the PLA were observed by TGA and DSC analysis, respectively. In respect to the mineralization, it was noted that the clay Cloisite 20A showed no significant influence on the biodegradation of PLA. On the other hand, the clay Cloisite 30B led to decreased levels of mineralization compared to the polymer, which may be related to an antimicrobial activity of its modifying agent. In the evaluation of hydrolytic degradation it was verified that the presence of organoclays can decrease the rate of degradation possibly by the action of its layers as a barrier. Nevertheless, even in the case of nanocomposites, the molecular weight reduction was significant, indicating that the composting process is favorable to the chain scission of the polymer in the studied materials. In the analysis performed by the bioassay using the test organism Allium cepa, it was verified that after degradation of PLA and the nanocomposites, the organic compost showed an reduction of the mitotic index and an increasing in the induction of chromosomal abnormalities. These results were statistically significant in relation to negative control (distilled water). By comparing the results obtained for the nanocomposites in relation to pure polymer, there were no statistically significant differences. The types of chromosomal aberrations observed indicate a possible genotoxic effect of materials, which may be related to an aneugenic action of the degradation products of PLA / Abstract: In this study, nanocomposites of PLA with organoclays Cloisite 20A and Cloisite 30B were prepared by the melt intercalation method. The materials were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). The influence of organoclays in the biodegradation process of PLA was assessed by quantifying the rate of mineralization according to ISO 14855-2, in simulated composting conditions. The influence of clays on the hydrolytic degradation process of PLA was also investigated by visual analysis and monitoring of molecular weight after periods of 15 and 30 days of degradation in organic compost. Given the lack of information related to ecotoxicity of biodegradable polymers, the assessment of citotoxic, genotoxic and mutagenic effects of the organic compost, after the materials degradation, was carried out using the bioassay with Allium cepa as test organism. The nanocomposites presented an intercalated structure, evidenced by XRD analysis. The TEM micrographs allowed the observation of different dispersion levels, including exfoliated regions. After incorporation of organoclays, a reduction of thermal stability and an increasing in the degree of crystallinity of the PLA were observed by TGA and DSC analysis, respectively. In respect to the mineralization, it was noted that the clay Cloisite 20A showed no significant influence on the biodegradation of PLA. On the other hand, the clay Cloisite 30B led to decreased levels of mineralization compared to the polymer, which may be related to an antimicrobial activity of its modifying agent. In the evaluation of hydrolytic degradation it was verified that the presence of organoclays can decrease the rate of degradation possibly by the action of its layers as a barrier. Nevertheless, even in the case of nanocomposites, the molecular weight reduction was significant, indicating that the composting process is favorable to the chain scission of the polymer in the studied materials. In the analysis performed by the bioassay using the test organism Allium cepa, it was verified that after degradation of PLA and the nanocomposites, the organic compost showed an reduction of the mitotic index and an increasing in the induction of chromosomal abnormalities. These results were statistically significant in relation to negative control (distilled water). By comparing the results obtained for the nanocomposites in relation to pure polymer, there were no statistically significant differences. The types of chromosomal aberrations observed indicate a possible genotoxic effect of materials, which may be related to an aneugenic action of the degradation products of PLA / Mestrado / Ciencia e Tecnologia de Materiais / Mestra em Engenharia Química
62

Preventive control of ammonia and odor emissions during the active phase of poultry manure composting

Zhang, Wenxiu 05 1900 (has links)
Traditional measures used in the composting industry for ammonia and odor emissions control are those involving collection and treatment such as thermal oxidation, adsorption, wet scrubbing and biofiltration. However, these methods do not address the source of the odor generation problem. The primary objective of this thesis research was to develop preventive means to minimize ammonia and odor emissions, and maximize nitrogen conservation to increase the agronomic value of compost. Laboratory-scale experiments were performed to examine the effectiveness of various technologies to minimize these emissions during the active phase of composting. These techniques included precipitating ammonium into struvite in composting matrix before it release to outside environment; the use of chemical and biological additives in the form of yeast, zeolite and alum; and the manipulation of key operational parameters during the composting process. The fact that struvite crystals were formed in manure composting media, as verified by both XRD and SEM-EDS analyses, represents novel findings from this study. This technique was able to reduce ammonia emission by 40-84%, while nitrogen content in the finished compost was increased by 37-105%. The application of yeast and zeolite with dosages of 5-10% enhanced the thermal performance of composting and the degree of degradation, and ammonia emission was reduced by up to 50%. Alum was found to be the most effective additive for both ammonia and odor emission control; ammonia emission decreased by 45-90% depending on the dosage, and odor emission assessed via an dynamic dilution olfactometer was reduced by 44% with dosages above 2.5%. This study reaffirmed that aeration is the most influential factor to odor emission. An optimal airflow rate for odor control would be 0.6 L/min.kg dry matter with an intermittent aeration system. Quantitative relationships between odor emission and key operational parameters were determined, which would enable “best management practices” to be devised and implemented for composting. An empirical odor predictive model was developed to provide a simple and direct means for simulation of composting odor emissions. The effects of operating conditions were incorporated into the model with multiplicative algorithm and linearization approximation approach. The model was validated with experimental observations. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate
63

Evaluation de la robustesse d'un système de biofiltration de gaz de compostage : approche structurelle et fonctionnelle / Evaluation of the robustness of a biofiltration system for composting gas : structural and functional approach

Cabrol, Léa 20 May 2010 (has links)
Dans un contexte interdisciplinaire, l'étude a consisté à évaluer le niveau de robustesse de procédés pilotes de biofiltration appliqués au traitement d'un effluent caractéristique des émissions de compostage de boues d'épuration, soumis à des fluctuations de charge transitoires, répétées, et d'intensité croissante. L'impact de ces perturbations a été examiné à deux niveaux, par la mesure de la résultante fonctionnelle de dégradation d'une part, et par la caractérisation de la structure génétique de la communauté bactérienne totale d'autre part. La mise en relation de ces deux composantes a fait l'objet d'une attention particulière. / The study aimed to evaluate the robustness capacity of pilot-scale biofilters applied to the treatment of sludge-composting emissions. The biofilters were submitted to repeated periodic fluctuations (shock loads) of increasing intensity. Their response was evaluated at two levels: functional resistance and resilience in terms of removal efficiency, and molecular characterization of the bacterial community structure. The objective was to establish the potential links between these two components.
64

Management nakládání s komunálními odpady v Jindřichově Hradci / Management of Municipal Waste Management in Jindřichův Hradec

Růžička, Jan January 2014 (has links)
This thesis is focused on the analysis of the current system of municipal waste management in Jindřichův Hradec. The aim was to evaluate the development of waste in a further evaluate the development of revenue and expenditure of city waste management. Another objective was to determine whether residents of housing estate Hvězdárna and Vajgar in Jindřichův Hradec sort waste and whether the class also biological waste. Also investigated were the reasons why the inhabitants of settlements not sorted waste and organic waste. Furthermore, we were determined according to sorting waste and by age, gender and educational attainment of respondents. This survey was conducted by personal interview in the streets of housing estate Hvězdárna and Vajgar in Jindřichův Hradec. The results of this survey were fundamental for the subsequent third objective, which was to propose appropriate measures that will lead to more efficient collection of sorted waste, and thereby reduce the amount of waste deposited in landfills.
65

Countering the porcelain dream: key findings from an evaluation of the global nitrogen cycle, a fundamental characterization of fresh faeces, and a campus composting toilet

Remington, Claire M. 06 January 2020 (has links)
When we consider global sanitation from within the framework of sustainable development, we are both failing to meet the needs of the present and are jeopardizing the capacity of future generations to do so. The primary function of sanitation and waste treatment is the protection of public health, but it is urgent that we also consider the long-term sustainability of sanitation and waste treatment systems. Our choice of sanitation and waste treatment systems is intimately connected to the greatest equity and sustainability challenges of our time, and we need something better than the Porcelain Dream (i.e. flush toilets, sewerage, and centralized conventional wastewater treatment). This thesis explores the design of sustainable sanitation systems from three different but complementary perspectives: 1. In a material flow analysis (MFA), I evaluate the positive impact of ecological sanitation (or the reuse of nutrients in excreta for agriculture) as an intervention to mitigate nitrogen pollution and improve stewardship of the global nitrogen cycle. I find that ecological sanitation can substitute 51% of nitrogenous fertilizer use, reduce discharge of nitrogen to waterways by 71%, decrease nitrous oxide (N2O) emissions by 34%, and improve the circularity of the agricultural-sanitation nitrogen cycle by 22%. 2. Through environmental engineering research, I derive fundamental drying characteristics of fresh faeces to support the development of ecological and sustainable sanitation. Based on this characterization, I propose the use of the Guggenheim, Anderson, and de Boer (GAB) model for predicting the relationship between water activity (aw) and equilibrium moisture content, calculating the heat of sorption, and estimating the corresponding energy requirements for drying of fresh faeces. Given an anticipated range of initial moisture contents of 63 to 86%, I estimate an energy requirement of 0.05 to 0.4 kJ/mol to inactivate pathogens in fresh faeces. 3. Via an evaluation of the composting toilet project at the University of Victoria (UVic), I explore factors critical to promoting a paradigm shift from the conventional to more ecological and sustainable systems. I identify the following as factors that facilitated implementation in the Exploration and Adoption/Preparation phases: supportive and self-reinforcing research and outcomes, favorable adopter characteristics, and the technology’s beneficial features. The overall objective of the research is to communicate that the design of sustainable sanitation systems is urgent, with implications both locally and globally, and to provide information to support a shift towards more sustainable sanitation systems. / Graduate / 2020-12-11
66

Composting in the Urban Environment Utilizing Yard Waste and Food Waste in Fairfax County, Virginia

Argandona, Walter Solio 21 February 2020 (has links)
Urbanization alters the natural soil structure of landscapes. This has a negative impact on the environment. This degradation of the soil in the urban environment needs management practices that protect and restore the nutrient value in the soil. Soil is one of the most essential elements of landscapes. High quality soils make a major contribution to cleaning water, acting as a filtration system that purifies the water it absorbs. Soil also sustains microorganisms that promote vegetation growth and consequently food production, one of the most important human activities that allows us to thrive as a society. The poor soil conditions in the urban environment make it very difficult to sustain healthy trees and vegetation. Urban soil is "modified through the regrading, compaction, cutting and filling, and, sometimes, contamination that comes with creating buildings, roads and associated land uses", changing the physical, chemical and biological structure of soil. (Trowbridge and Bassuk 3) In general, urban areas require better waste management methods that could use an abundant resource of food and yard waste to make compost. This thesis focuses on composting organic waste in the McNair neighborhood of Fairfax County in order to produce a resource to improve the soil conditions. This improvement would support the vegetation in this urban environment, and, in addition, sequester carbon and divert materials that otherwise would go to landfills. This thesis demonstrates a sustainable method for composting food and yard waste in a mixed-use community in northern Virginia turning waste material into a resource. / Master of Landscape Architecture / The growth of cities has a negative impact on the native soil and vegetation. The expansion of urban areas weakens the microorganisms that live in the soils through soil compaction for the construction of roads and buildings, runoff pollution and the use of chemicals in lawns and gardens. These urban conditions challenge the growth of trees and vegetation in general. Using sustainable waste management practices in cities we can turn organic waste material and turn it into an organic fertilizer to sustain the microorganisms in the soil and promote the growth of vegetation in urban areas. This thesis focuses in composting food waste and yard waste in the McNair neighborhood in Fairfax in order to turn a waste material into a local resource that benefits the community by sustaining green areas and diverting organic waste from going to landfills.
67

Considerations for Informed Pursuit of Zero Waste: Lessons from Two Case Studies

Thangavelu, Jennifer Anne 14 November 2013 (has links)
Starting in the early 2000s, a number of U.S. communities have adopted "zero waste" commitments to reduce waste as much as possible through recycling, composting, and other means. Little in-depth information exists about the impetus for or efficacy of these efforts. The author sought to build knowledge on the topic by conducting case studies of two communities: the zero waste efforts of Boulder, Colorado, and the Zero Waste Zones established in Atlanta. The two cases presented an interesting contrast, in terms of sector driving zero waste: public in Boulder, and private in Atlanta. The study aimed to use the experiences of these two communities, supplemented with background research on materials management and application of relevant theory, to develop a set of considerations for more informed pursuit of zero waste. The author gathered qualitative data by conducting unstructured interviews of the actors involved with the zero waste efforts in Boulder and Atlanta. Interview questions concerned, e.g., zero waste goals and plans, the impacts of zero waste on the business or organization, and influential individuals or organizations. The study produced the following set of considerations: Definition of waste determines priorities and impacts of zero waste efforts; responsibility for waste arbitrarily resides with consumers and local government instead of producers; the private, public, and nonprofit sectors each play important roles in waste reduction; local government should not bear the full burden of materials management; and state and federal government can offer useful policy tools to advance zero waste. / Master of Urban and Regional Planning
68

Feasibility study of biological treatment of organic waste in Tsumeb Municipality, Namibia.

Diebels, Jesper January 2014 (has links)
This study is part of a larger project in which the Tsumeb municipality, Falun municipality and Falu Energi & Vatten AB work together to change the currently used controlled waste dumping site in Tsumeb into a sanitary landfill. This study aims to recommend a MSWM solution that will divert the organic waste from going to the landfill. The study consist out of a literature study in order to establish a theoretical background for the MSWM solution; a field study in which the current waste flows of Tsumeb were quantified, by using current data, and characterized, by performing a hand-picking analyses according to the UNEP methodology; and an analyses section in which an appropriate MWSM solution was proposed. The current waste consist out of 70% sand and stones, 17% grass and leaves, 6% prunings and trimmings, 4% sewage sludge, 3% branches and stumps, and 1% of other waste. This paper concludes that 99% of the organic waste in Tsumeb can be recycled, by using it as covering material, as biofuel and turning it into compost. This paper also shows that there is a potential for Tsumeb to start economically sound composting facility.
69

Niche applications of in-vessel composting

von Fahnestock, Frank Michael 10 October 2005 (has links)
No description available.
70

Composting in the Urban Environment Utilizing Yard Waste and Food Waste in Fairfax County, Virginia

Argandona, Walter Solio 21 February 2020 (has links)
Urbanization alters the natural soil structure of landscapes. This has a negative impact on the environment. This degradation of the soil in the urban environment needs management practices that protect and restore the nutrient value in the soil. Soil is one of the most essential elements of landscapes. High quality soils make a major contribution to cleaning water, acting as a filtration system that purifies the water it absorbs. Soil also sustains microorganisms that promote vegetation growth and consequently food production, one of the most important human activities that allows us to thrive as a society. The poor soil conditions in the urban environment make it very difficult to sustain healthy trees and vegetation. Urban soil is "modified through the regrading, compaction, cutting and filling, and, sometimes, contamination that comes with creating buildings, roads and associated land uses", changing the physical, chemical and biological structure of soil. (Trowbridge and Bassuk 3) In general, urban areas require better waste management methods that could use an abundant resource of food and yard waste to make compost. This thesis focuses on composting organic waste in the McNair neighborhood of Fairfax County in order to produce a resource to improve the soil conditions. This improvement would support the vegetation in this urban environment, and, in addition, sequester carbon and divert materials that otherwise would go to landfills. This thesis demonstrates a sustainable method for composting food and yard waste in a mixed-use community in northern Virginia turning waste material into a resource. / Master of Landscape Architecture / The growth of cities has a negative impact on the native soil and vegetation. The expansion of urban areas weakens the microorganisms that live in the soils through soil compaction for the construction of roads and buildings, runoff pollution and the use of chemicals in lawns and gardens. These urban conditions challenge the growth of trees and vegetation in general. Using sustainable waste management practices in cities we can turn organic waste material and turn it into an organic fertilizer to sustain the microorganisms in the soil and promote the growth of vegetation in urban areas. This thesis focuses in composting food waste and yard waste in the McNair neighborhood in Fairfax in order to turn a waste material into a local resource that benefits the community by sustaining green areas and diverting organic waste from going to landfills.

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