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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.
521

An evaluation of invertebrate dynamics in a drinking water distribution system: a South African perspective

Shaddock, Bridget 16 October 2008 (has links)
M.Sc. / The occurrence of invertebrates in drinking water supplies is a common consumer complaint with studies showing that very few drinking water distribution networks are totally free of organisms. A detailed investigation of different types of metazoan animals in the drinking water supply networks of South Africa has not been undertaken. In limited worldwide studies, invertebrates (mainly Amphipoda, Chironomidae, Cladocera, Copepoda and Ostracoda) have been detected in produced drinking water. In countries that have started monitoring these organisms, the quality of the produced water has improved due to the improved methods of filtering. The occurrence of “worms” (Nematodes and Diptera) and Crustaceans decreases the aesthetic value of the drinking water, and pathogenic organisms, which may also be associated with them, can affect human health. Limited reference works have been compiled during the conducted studies on drinking water distribution networks throughout the world. All fresh water invertebrates have the potential to be passed into the drinking water supply network (Rising mains, pipelines, reservoirs, and consumer taps). There are few complete reference works available for fresh water invertebrates occurring in the fresh water sources and those of Southern Africa. Therefore, there are no reference works regarding fresh water invertebrates that can be used to monitor drinking water supply networks in South Africa. / Prof. J.H.J. van Vuren
522

Hybrid ion exchanger supported metal hydroxides for the removal of phosphate from wastewater

De Kock, Luéta-Ann 12 November 2015 (has links)
Ph.D. (Chemistry) / Phosphorus in the form of phosphate needs to be removed from the aqueous environment as it is primarily responsible for eutrophication of water bodies. In an attempt to limit the discharged of phosphorus into the aqueous environment, the phosphate discharge limits for wastewater treatment plants have been decreased. These limits are not easily or economically met by current phosphorus removal technologies. In addition phosphorus is a non-renewable resource. To ensure the ongoing quality of water bodies and security of food production it is vital that phosphate in water be removed and recovered. In order to address these issues, novel hybrid metal oxide ion exchange resins based on Fe(III), Cu(II), Mn(IV and Ti(IV) oxides have been prepared and their phosphate adsorption characteristics determined.
523

Desinfecção da água por pasteurização solar (SOPAS) em comunidades rurais / Water disinfection by solar pasteurization (SOPAS) in rural communities

Rodrigues, Danielle Gonçalves, 1981- 18 August 2018 (has links)
Orientadores: José Euclides Stipp Paterniani, Franco Giusepe Dedini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-18T19:44:20Z (GMT). No. of bitstreams: 1 Rodrigues_DanielleGoncalves_M.pdf: 3768506 bytes, checksum: 1229ddc9f91b3c65c3898169d390236d (MD5) Previous issue date: 2011 / Resumo: A elevada incidência de doenças de veiculação hídrica, devido à ausência de um sistema de saneamento suficientemente eficaz, afeta principalmente as populações que vivem em localidades pobres e em zonas rurais. Dessa forma, busca-se desenvolver cada vez mais, meios alternativos e baratos para promover a melhoria da qualidade de vida dessa população. Neste estudo é apresentado um sistema de pasteurização solar da água (SOPAS) visando desinfecção de água para consumo humano, utilizando como insumo um equipamento de aquecedor solar comercial e dois de baixo custo. Realizou-se testes para verificação da inativação de bactérias do grupo coliformes e heterotróficas nos aquecedores utilizados, os quais ficavam expostos por 8 horas ao sol, durante o período de maio de 2009 a novembro de 2010. Para detecção do grupos coliformes, usou-se a técnica do substrato cromogênico e para a heterotróficas o plaqueamento com Plate Agar Conter. De todos os equipamentos estudados, somente o equipamento de aquecedor solar comercial atingiu a temperatura de 60 º C, necessária para promoção da SOPAS, inativando o grupo coliformes. As bactérias heterotróficas não foram inativadas por nenhum dos equipamentos estudados. Para o desenvolvimento desse estudo, utilizou-se ferramentas de metodologia de projeto como: QFD e benchmarking. Isso possibilitou a realizar entrevistas em zonas rurais de modo a se verificar as condições dessas populações e propor medidas para desenvolver um equipamento para promoção da SOPAS de fácil aceitação e de custo acessível baseado nas necessidades reais do público alvo / Abstract: The high incidence of diseases caused by contaminated water, due to lack of an effective sanitation system, affects people who live in undeveloped and rural areas. In this way, the development of alternative and capable solutions improving the people quality life is researched. This research work introduces the water solar pasteurization system (SOPAS), objectiving water disinfection destined to people consumption, analyzing performance between three equipments being commercial solar heater equipment and two low cost equipments. Tests have been carried on to verify the coliform and heterotrophic bacterial group inactivation on used heaters, which have been exposed for 8 hours under sun, though May, 2009 to November, 2010. Coliform group detection has been applied the chromogenic substrate technique and heterotrophic group detection has been applied the Agar Plate Conter plating technique. It is observed among every tested equipments that only commercial solar heater reached temperature of 60°C, which is necessary to promote the (SOPAS), inactivating the coliform groups. Heterotrophic bacteria groups have not been for any tested equipments. This research work has been applied methodological project tools as: QFD and benchmarking. It allowed carrying on interviews in rural areas, in way to verify conditions of these populations and possibility to purpose actions to develop an equipment to promotion the (SOPAS) as easy acceptance and accessible cost based on real necessities of target public / Mestrado / Agua e Solo / Mestre em Engenharia Agrícola
524

Nanopartículas de prata produzidas por ablação à laser em água deionizada / Silver nanoparticles produced by laser ablation in deionized water

Villegas Borrero, Nelson Fabian, 1984- 29 August 2018 (has links)
Orientadores: Francisco das Chagas Marques, Carlos Lenz César / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-29T22:06:44Z (GMT). No. of bitstreams: 1 VillegasBorrero_NelsonFabian_M.pdf: 7427305 bytes, checksum: 95d120bd4cca81a54f7e8af57dfd2ab5 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho foram fabricadas nanopartículas metálicas de prata (NPsM de Ag) em soluções coloidais usando a técnica de ablação à laser. Parâmetros como o comprimento de onda do laser, energia do pulso e a taxa de repetição afetam a distribuição de tamanho das NPsM. Assim, neste trabalho estudamos a influência destes parâmetros sobre o tamanho das NPsM de Ag. Para isto foi feita uma montagem experimantal na qual um alvo de prata é imerso em um líquido e irradiado por um pulso de laser de Nd:YAG para criar soluções coloidais. Foi encontrada uma variação dos picos de absorção entre = 394nm e = 405nm. Segundo a previsão da teoria de Gustav Mie, as variações nos picos tem a ver com a variação na distribuição de tamanhos. Para comprovar estes resultados foi feita uma estimativa do tamanho médio das NPsM de Ag usando a análise de imagens tomadas com o Microscópio Eletrônico de Varredura (MEV) e a técnica de Espalhamento Dinâmico da Luz (DLS). O espectro experimental e a teoria de Gustav Mie (simulação feita usando o software mathematica) encontram-se em concordância. As NPsM produzidas foram usadas para medir o efeito de aumento no sinal Raman em superfícies (SERS) encontrando-se que o sinal do espalhamento Raman de corantes usados em diferentes pesquisas (Rodâmina B e N719) aumenta com o uso das NPsM / Abstract: In this work we fabricated silver nanoparticles (Ag NPs) in colloidal solutions with specific sizes. Parameters like laser wavelength, pulse energy and pulse repetition rate affect the distribution of NPs size. In this work we studied the influence of these parameters on the size of Ag NPs. For that purpose we mount a set-up in which a silver target was immersed in liquid and irradiated by Nd:YAG pulsed laser to create different colloids. We found that the absorption peak of these colloids lays between 394nm and 405nm. We estimated a mean size of Ag NPs from images taken by Scanning Electron Microscope (SEM) and Dynamic Ligth Scattering (DLS). The calculated absorption spectra and simulation through Gustav Mie theory (Simulated in Matthemathica software) were in good agreement. The produced NPs were used in Enhacement Raman Spectroscopy (SERS) measurements, finding that the signal of Rhodamina B and N719 Dyes increases using these NPsM / Mestrado / Física / Mestre em Física / 1247650/2013 / CAPES
525

Tratamento de efluentes da carcinicultura por flotação em coluna e flotação.

Melo, José Francisco de Araújo 01 June 2010 (has links)
Submitted by Biblioteca Central (biblioteca@unicap.br) on 2017-11-22T18:12:19Z No. of bitstreams: 1 dissertacao_jose_francisco_araujo_melo.pdf: 749901 bytes, checksum: e18014a99b9a2a95d319c1dba4ad0733 (MD5) / Made available in DSpace on 2017-11-22T18:12:19Z (GMT). No. of bitstreams: 1 dissertacao_jose_francisco_araujo_melo.pdf: 749901 bytes, checksum: e18014a99b9a2a95d319c1dba4ad0733 (MD5) Previous issue date: 2010-06-01 / The high productivity in the breeding of shrimp makes it necessary to approach some aspects to their sustainability, particularly the aquatic environment of the nursery. Thus, the treatment of effluents originating from the shrimp becomes of fundamental importance, considering the need to minimize the environmental impacts generated by this productive activity. This study investigates the uses of flotation types of column and dissolved air to the treatment of shrimp effluent. The effluent used was from the farm Tabatinga, located on the north coast of Pernambuco State. Was performed physical-chemical and microbiological characterization of effluent being obtained parameters consistent with those found in the literature. A column flotation bench was used in experimental trials, being employed an experimental design with two variables (pH and air flow) to evaluate the removal of turbidity of the effluent. The effect of adding a flocculant was also investigated. The FAD cell experiments were performed with pressure values of 3 and 6 bar, and a pH of 5.8 and 9.8, and additional experiments were performed using an anionic collector. The results of column flotation for the effluent from the beginning of culture showed that the turbidity decreases with increasing air flow and the decrease in pH after 40 minutes of the proceedings, was obtained as best fit a linear model with interaction. The presence of flocculant concentration of 0.1% (p / v) at pH 7.8 showed a removal of turbidity of only 25% for the condition of lower air flow. For the treatment of effluent from the end of cultivation, the turbidity removal also increased with increasing air flow and with decreasing pH, reaching a maximum removal of about 40% after 35 minutes of the proceedings, with an adjustment quadratic model. In dissolved air flotation effluent end of the cultivation, the highest percentage of turbidity removal were obtained at pH 5.8, reaching values of 52 and 47% for operating pressures of 3 and 6 bar, respectively. In the presence of an anionic collector, there was an increase in the removal of turbidity values between 56 and 65%. / A elevada produtividade nos criadouros de camarão torna necessária a abordagem de alguns aspectos para sua sustentabilidade, principalmente do ambiente aquático dos viveiros. Dessa forma, o tratamento de efluentes originados da carcinicultura torna-se de fundamental importância, considerando a necessidade de minimizar os impactos ambientais gerados por essa atividade produtiva. O presente trabalho investiga os usos das flotações dos tipos por coluna e ar dissolvido para o tratamento de efluentes da carcinicultura. O efluente utilizado foi proveniente da fazenda Tabatinga, localizada no litoral norte do Estado de Pernambuco. Foi realizada a caracterização físico-química e microbiológica dos efluentes, sendo obtidos parâmetros condizentes com os encontrados na literatura. Uma coluna de flotação de bancada foi utilizada nos ensaios experimentais, sendo empregado um planejamento experimental com duas variáveis (pH e vazão de ar) visando avaliar a remoção de turbidez do efluente. O efeito da adição de um floculante(Bozefloc CE 340 líquido) também foi investigado. Os experimentos em célula FAD foram realizados com valores de pressão de 3 e 6 bar, e pH de 5,8 e 9,8, e experimentos adicionais foram realizados utilizando um coletor aniônico. Os resultados de flotação em coluna para o efluente do início do cultivo demonstraram que a turbidez diminui com o aumento da vazão e com a diminuição do pH após 40 minutos de processo, sendo obtido como melhor ajuste um modelo linear com interação. A presença do floculante na concentração de 0,1% (p/v) a pH 7,8 demonstrou uma remoção de turbidez de apenas 25% para a condição de menor vazão de ar. Para o tratamento do efluente do fim do cultivo, a remoção de turbidez também aumentou com o aumento da vazão de ar e com a diminuição do pH, atingindo um valor máximo de remoção de cerca de 40% após 35 minutos de processo, com um ajuste quadrático do modelo. Na flotação por ar dissolvido do efluente do fim do cultivo, os maiores percentuais de remoção de turbidez foram obtidos a pH 5,8, atingindo valores de 52 e 47% para pressões de operação de 3 e 6 bar, respectivamente. Na presença de um coletor aniônico(Flomin-C-5435), observou-se um aumento na remoção da turbidez para valores entre 56 e 65%.
526

Self-assembled Block Copolymer Membranes with Bioinspired Artificial Channels

Sutisna, Burhannudin 04 1900 (has links)
Nature is an excellent design that inspires scientists to develop smart systems. In the realm of separation technology, biological membranes have been an ideal model for synthetic membranes due to their ultrahigh permeability, sharp selectivity, and stimuliresponse. In this research, fabrications of bioinspired membranes from block copolymers were studied. Membranes with isoporous morphology were mainly prepared using selfassembly and non-solvent induced phase separation (SNIPS). An effective method that can dramatically shorten the path for designing new isoporous membranes from block copolymers via SNIPS was first proposed by predetermining a trend line computed from the solvent properties, interactions and copolymer block sizes of previously-obtained successful systems. Application of the method to new copolymer systems and fundamental studies on the block copolymer self-assembly were performed. Furthermore, the manufacture of bioinspired membranes was explored using (1) poly(styrene-b-4-hydroxystyrene-b-styrene) (PS-b-PHS-b-PS), (2) poly(styrene-bbutadiene- b-styrene) (PS-b-PB-b-PS) and (3) poly(styrene-b-γ-benzyl-L-glutamate) (PSb- PBLG) copolymers via SNIPS. The structure formation was investigated using smallangle X-ray scattering (SAXS) and time-resolved grazing-Incidence SAXS. The PS-b- PHS-b-PS membranes showed preferential transport for proteins, presumably due to the hydrogen bond interactions within the channels, electrostatic attraction, and suitable pore dimension. Well-defined nanochannels with pore sizes of around 4 nm based on PS-b- PB-b-PS copolymers could serve as an excellent platform to fabricate bioinspired channels due to the modifiable butadiene blocks. Photolytic addition of thioglycolic acid was demonstrated without sacrificing the self-assembled morphology, which led to a five-fold increase in water permeance compared to that of the unmodified. Membranes with a unique feather-like structure and a lamellar morphology for dialysis and nanofiltration applications were obtained from PS-b-PBLG copolymers, which exhibited a hierarchical self-assembled morphology with confined α-helical polypeptide domains. Our results suggest that bioinspired nanochannels can be designed via block copolymer self-assembly using classical methods of membrane preparation. Investigation of the membrane formation mechanism leads us to a better understanding of the design strategies for the development of self-assembled nanochannels from block copolymers. In further outlook, our research could give a contribution to the discovery of future generation materials for water purification and desalination, as well as biological separation.
527

An Investigation into Bromate Formation in Ozone Disinfection Systems

Storlie, Leslee January 2013 (has links)
Ozonation is used as an alternative disinfection process to chlorination but unfortunately has a potential of oxidizing bromide, a natural component of water sources, to bromate. Bromate is a possible carcinogen with a maximum contaminant level of 10 ppb. To understand bromate formation in full-scale systems, a comprehensive study was conducted at the Moorhead Water Treatment Plant (WTP). Bromide concentrations in source waters were monitored. Water samples from locations in the ozonation chambers were collected and analyzed for bromate and other parameters. Results showed that bromate formation was increased through increases in pH, bromide, and ozone dose during high temperatures and was decreased by increases in organics. The impact of the bromate influential parameters was minimized at low temperatures. To assist Moorhead WTP on developing bromate control strategies, a modeling approach was adopted to predict bromate formation at various operational conditions using temperature, pH, ozone dose, bromide, and TOC. / MWH Global, AWWA Scholarship / American Water Works Association (AWWA), Minnesota and North Dakota sections / North Dakota Water Resources Research Institute / Department of Civil Engineering, North Dakota State University
528

Development of Operational Strategies to Minimize Bromate Formation in the Moorhead Water Treatment Plant

Young, Kevin Bradley January 2014 (has links)
A recent study at the Moorhead water treatment plant (MWTP) determined that bromate formed during ozone disinfection and, at times, exceeded the maximum contaminant level (MCL) of 10 parts per billion (ppb) in the summer months. Operational data showed that bromate formation was directly related to raw water bromide concentration and control of the ozone system. This study was conducted with the purpose of developing and implementing operational strategies to minimize bromate formation in the MWTP. Several operational changes, including selection of source water based on bromide concentration and controlling ozone addition in a manner that reduces the ozone dose used to achieve disinfection, were implemented and were effective at minimizing bromate formation in the ozone chambers. The bromate concentration in the finished drinking water was significantly reduced and only a few samples contained greater than 10 ppb bromate. / Moorhead Public Service / American Water Works Association
529

Design and Modelling of a Container for Optimal Flow Rate and Wastewater Purification

Stenlund, Olle January 2021 (has links)
Industries are becoming more aware of how they use water in their production process. In many cases, they release wastewater back into the water supply untreated, which can cause adverse side effects to the ecosystem. A sustainable environment requires efficient water purification. One approach to purify wastewater uses rotating bed reactors. An impeller filled with catalyst pellets that absorb the pollutants spins in the contaminated fluid. The inertial forces from the spinning impeller propel the contaminated water through the packed bed and purify it. In this study, we used one of these rotating bed reactors. However, the motors that drive these impellers can be bulky and may not be compatible with some tanks or environments. To solve this problem, we designed, constructed, and tested a container around the impeller that provides maximal outflow, using only the impellers pumping capability. We also developed a CFD simulation of the container to analyze the internal flows and forces. Because the flow generated by the rotating impeller displaces the fluid in a radial direction, the design works as a custom-made centrifugal pump. We constructed the container using plastic and wood with an outlet nozzle made of metal. The container's pump capability was around 2.5 liters per second when the impeller spun at 300 RPM. The developed CFD simulations gave a higher flow rate at 3.1 liters/second but overall helped shed light on the internal forces happening inside the container during high RPM testing. The design could generate a sufficient outflow of fluids, converting kinetic fluid energy to fluid pressure energy at the outlet, causing a pump effect. Overall, the design proved sturdy and could handle the forces occurring inside the container. The implementation of this design could allow industries to more efficiently and ergonomically utilize the purifying capabilities of the RBR in otherwise complex scenarios. By purifying wastewater before releasing it back into the water supply, we can take immediate action in achieving a sustainable environment.
530

Electrochemical analysis of selected polychlorinated biphenyls and contaminated water remediation using polyaniline coated sawdust

Okumu, Fredrick Oluoch January 2012 (has links)
Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2012. / Polychlorinated biphenyls (PCBs) are known harmful chemicals which require urgent remediation, monitoring and assessment in the environment. The predominant current methods used to analyze PCBs involve expertise and are cost intensive. Most of these methods are chromatographic based techniques which are difficult to sustain in Africa due to the expensive nature of the instrument, costly running expenses and skilled labour required. These limitations face Africans, who are the most affected by the presence of PCBs in their environment as a result of improper disposal and usage of these compounds.

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