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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.
271

Rural community privy sanitation program a dissertation submitted in partial fulfillment ... Master of Science in Public Health ... /

Cushman, Edwin Delmont. January 1934 (has links)
Thesis (M.S.P.H.)--University of Michigan, 1934.
272

Rural sewage disposal a thesis submitted in partial fulfillment ... Master of Science in Public Health ... /

Carr, Carl W. January 1939 (has links)
Thesis (M.S.P.H.)--University of Michigan, 1939.
273

Sewage disposal and water supply in rural areas a major term report submitted in partial fulfillment ... Master of Public Health ... /

Simpson, E. W., January 1947 (has links)
Thesis (M.P.H.)--University of Michigan, 1947.
274

Rural community privy sanitation program a dissertation submitted in partial fulfillment ... Master of Science in Public Health ... /

Cushman, Edwin Delmont. January 1934 (has links)
Thesis (M.S.P.H.)--University of Michigan, 1934.
275

A review of the use of salt water for flushing in Hong Kong : project report /

Ip, Chi-kuen. January 1900 (has links)
Thesis (M. Sc.)--University of Hong Kong, 1993.
276

Hydraulics of duckbill valve jet diffusers /

Karandikar, Jaydeep Sharad. January 1997 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 115-120).
277

Phosphorus and iron loading to Lake Ontario from waste water treatment plants in Hamilton and Toronto /

Medeiros, Andrew. January 2005 (has links)
Thesis (M.A.)--York University, 2005. Graduate Programme in Environmental Studies. / Typescript. Includes bibliographical references (leaves 96-100). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11861
278

Enhancement of membrane surface characteristics to improve membrane performance and durability in the treatment of municipal MBR effluent

Kasongo Wa Kasongo, Godwill January 2018 (has links)
Thesis (Master of Engineering in Chemical Engineering))--Cape Peninsula University of Technology, 2018. / Fresh, clean water has always been critical for the world's social development. Supply of water can be reinforced through recycling and reuse; and secondary treatment of municipal wastewater effluent with a membrane bioreactor (MBR) followed by a reverse osmosis (RO) process, has emerged as a crucial treatment process for water reuse. However, fouling of RO membranes in such process is unavoidable. This leads to poor performance, increase in operational cost and degradation of the membrane material, which reduces the membrane life span. Various researches have been conducted to provide an understanding of the mechanism of fouling, and methods have been developed to minimize it. In this research, the effect of surface modification to minimise fouling on a thin film composite polyamide RO membrane was investigated. This study was divided into three parts, namely: membrane modification, biofouling and filtration using RO. Two modifying agents, PVA and DMAEMA, were used as grafting solutions. Escherichia coli (E. coli) were used as the biofoulant to study the ant-biofouling properties of the membranes. A make-up synthetic MBR secondary effluent feed was used in a bench scale RO process. During the membrane modification process, the membrane was treated using two different approaches. Firstly, the covalent attachment of polyvinyl alcohol (PVA) through Glutaraldehyde (GA) onto the surface and secondly the redox initiated grafting of dimethyl amino ethyl methacrylate (DMAEMA PVA and DMAEMA grafting solutions were applied at four different concentrations). The PVA and DMAEMA modifying agents were successfully grafted onto the membrane top layers and were confirmed by the functional groups, present, using the Attenuated Total Reflectance–Fourier Transform Infrared spectroscopy (ATR-FTIR) spectra. The morphology of the membrane surfaces was investigated using Scanning Electron Microscopy (SEM), before and after treatment. SEM analysis showed better membrane structures with PVA grafting compared to DMAEMA.
279

Utilização da flotação em coluna para o tratamento de efluente da indústria láctea / Use of column flotation for the treatment of effluent from the dairy industry

Andréa Cavalcante Vilar 13 February 2009 (has links)
Os principais impactos ambientais causados pelas indústrias de laticínios estão relacionados ao lançamento dos efluentes líquidos, geralmente sem nenhum tipo de controle ou tratamento. O efluente lácteo é caracterizado pelo elevado teor de matéria orgânica, sendo de fundamental importância a implementação de técnicas de tratamento eficazes e de baixo custo. O presente trabalho tem como objetivo avaliar o desempenho de uma coluna de flotação operando em batelada para o pré-tratamento de um efluente lácteo. A primeira etapa consistiu em investigar os processos de floculação/sedimentação e flotação de um efluente lácteo sintético em seu ponto isoelétrico. Este foi preparado pela adição de leite em pó à água, sob agitação mecânica, de maneira a obter-se uma suspensão homogênea. Foi utilizada uma concentração de leite de 6,5% (p/v), visando simular as características de um efluente real. A condição ótima de floculação foi determinada através do teste de jarro pela adição de uma solução aquosa de HCl na proporção de 1:10 (v/v). Testes de sedimentação da suspensão na condição ótima de floculação foram realizados em duplicata por meio da observação do deslocamento da altura de flocos em função do tempo. A densidade dos flocos foi avaliada por meio da técnica de centrifugação e o diâmetro dos flocos foi determinado de acordo com equações que descrevem a fluidodinâmica de sistemas floculentos. O ensaio de flotação foi realizado em uma coluna operando em batelada. A condição ótima de floculação foi observada a pH 4,0, sendo obtida uma eficiência de recuperação dos flocos de 88% no teste de jarro. Os ensaios de sedimentação demonstraram que após cerca de 15 minutos os flocos já atingiam a região de compactação, sendo observada uma estabilização da altura do sedimento. A velocidade máxima de sedimentação observada foi semelhante para ambos os experimentos, com valores de 0,97 cm/min e 0,84 cm/min. A densidade e o diâmetro médio dos flocos foram de 1,0160,012 g/cm3 e 275 mm, respectivamente, e o percentual de recuperação dos sólidos foi de 93%, demonstrando a eficiência do processo de floculação/sedimentação para o tratamento primário de efluente lácteo sintético floculado. Por outro lado, a flotação não foi satisfatória, sendo observada a sedimentação dos flocos na coluna de flotação. Na segunda etapa do trabalho foi utilizado um efluente lácteo industrial (soro de queijo), obtido de uma pequena indústria localizada no Agreste pernambucano. A caracterização físico-química do efluente foi realizada em termos do teor de proteínas, cinzas, lipídios, carboidratos e pH. O efluente apresentou aproximadamente 5 g/100mL de carboidratos, 0,8 g/100mL de proteínas e 0,6 g/100mL de lipídios e um pH igual a 5,0. Não foi possível a observação visual de formação de flocos variando-se o pH da suspensão entre 2,5 e 5,5. Um Vilar, A.C. Utilização da flotação em coluna para o tratamento de efluente da indústria Láctea planejamento fatorial foi empregado para avaliar a eficiência da coluna de flotação na remoção da DQO do efluente, tendo como variáveis o pH e a vazão de ar do sistema. A máxima remoção de DQO (70%) foi atingida para uma vazão de ar de 1.362 mL/min, enquanto que o pH não apresentou-se como uma variável significativa. A eficiência de flotação atinge 76% na presença de um floculante catiônico a uma concentração de 0,1%. O efluente apresentou baixa hidrofobicidade, ponto isoelétrico a pH 4,0 e diâmetro médio de partícula de 0,43 mm. Os dados experimentais foram ajustados de maneira satisfatória a um modelo cinético de primeira ordem / The main environmental impacts caused by the dairy industries are related to discharge of liquid effluents, usually without any kind of control or treatment. The dairy effluent is characterized by high content of organic matter, being important the implementation of techniques for its effective treatment and low cost. This study aims to evaluate the performance of a flotation column operating in batch for the pre-treatment of a dairy effluent. The first step was to investigate the processes of flocculation / sedimentation and flotation of a synthetic dairy effluent in the isoelectric point. This was prepared by the addition of milk powder to water under mechanical stirring, to obtain a homogeneous suspension. It was used a milk concentration of 6.5% (w/v), aiming simulate the characteristics of a real effluent. The optimal condition of flocculation was determined using a jar test by the addition of an aqueous solution of HCl 1:10 (v/v). Settling tests using the flocculated suspension were performed in duplicate through the observation of the displacement of flocs along the time. Flocs density was evaluated through centrifugal technique and the flocs diameter was determined according equations that describe the flocculent systems fluidodynamic. Flotation test was carried out in a column operating in batch. The optimal condition of flocculation was observed at pH 4.0, with a flocs recovery efficiency of 88% in the jar test. Settling tests showed that after 15 minutes flocs had already reached the compactation region, being observed a stabilization of the sediment height. Settling maximum velocity was similar for both experiments, with values of 0.97 cm/min and 0.84 cm/min. Density and flocs diameter were 1,0160,012 g/cm3 and 275 mm, respectively, and the solids recovery efficiency was 93%, demonstrating the efficiency of the flocculation/sedimentation process for primary treatment of a flocculated synthetic dairy effluent. Moreover, flotation was not satisfactory, with a effluent sedimentation in the flotation column. In the second stage of work was used an industrial dairy effluent (obtained from cheese processing) from a small industry located in the agreste region of Pernambuco State. Physical-chemical characterization of effluent was made to determine the contents of protein, ash, lipids, carbohydrates and pH. The effluent had approximately 5 g/100mL carbohydrates, 0.8 g/100mL of proteins and lipids of 0.6 g/100mL and pH 5.0. The visual observation of flocs formation in the range pH 2,5 to pH 5,5 was not possible. A factorial design was used to evaluate the efficiency of the flotation column to remove the COD content, and the variables investigated were pH and air flow. The maximum removal of COD (70%) was achieved for an air flow of 1.362 mL/min, while pH was not statistically significant. Flotation efficiency reaches 76% in the presence of a flocculating agent in a concentration of 0.1%. The effluent showed low hydrophobicity, isoelectric point at pH 4.0 and mean particle diameter of 0.43mm. Experimental data were fitted satisfactorily to a first-order kinetic model
280

Prediction of the influent wastewater variables using neural network theory

Kriger, Carl January 2007 (has links)
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2007 / In order to develop an effective control strategy for the activated sludge process of a wastewater treatment plant, an understanding of the nature of the influent load disturbances to the wastewater treatment plant is necessary. Biological systems are among the most difficult to control and predict. Due to the complex biological reaction mechanisms, the highly time-varying, and multivariable aspects of the wastewater treatment plant ('MNTP), the diagnosis of the 'MNTP are still difficult in practice. The application of intelligent techniques, which can analyse the multi-dimensional nonlinear process data using a visualisation technique, can be useful for analysing and diagnosing the activated-sludge process in the VVVVTP. This complex capability for nonlinearity representation combined with the fact that no model exists for the WVVTP influent dynamics to a WVVTP, makes neural networks an ideal choice for a solution. Forecasting the behaviour of complex systems has been a broad application area for neural networks. Applications such as economic forecasting, electricity load I demand forecasting, and forecasting natural and physical phenomena have been extensively studied, hence the numerous papers presented at annual conferences in this focus area. The cognitive ability of artificial neural networks to map' nonlinear complex input-output relationships, which would allow for better prediction and corrective control of processes, make them particularly attractive. The values of the influent disturbances are usually measured off-line in ~ laboratory, as there are still no reliable on-line sensors available. This work presents the development of a neural network model for prediction of the values of the influent disturbances based on historical plant and weather data, which ultimately affect the activated sludge process. Three different neural networks including the multilayer perceptron, recurrent and radial basis functions neural network are developed for the prediction of the influent disturbances of Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN) and influent flow rate respectively. The application area is the prediction of the influent variables at a local municipal wastewater treatment plant. The forecast result is used for the determination of the setpoint to a controller, in order to• optimize plant performance. The results are first applied to a pilot wastewater treatment plant. Much hype exists surrounding the subject of neural networks, and they are sometimes described as 'computers that think'. This sort of definition creates unrealistic expectations and is one of the reasons why it is discredited. The results obtained will hopefully present helpful insights as to the scope and possibilities as to the application for neural networks, but also present the practical challenges which neural network practitioners and designers of intelligent systems face. The solution of the problem for development of the mathematical model for dynamic behaviour of the influent disturbances according to the influence of the weather conditions and the season of the year is the first attempt in the scientific and research literature so far.

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