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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.
171

Photosynthetic Oxygenation and Nutrient Utilization by Chlorella vulgaris in a Hybrid Membrane Bioreactor and Algal Membrane Photobioreactor System

Najm, Yasmeen Hani Kamal 11 1900 (has links)
Aerobic activated sludge membrane bioreactors (AS-MBR) in municipal wastewater treatment are compact systems that can efficiently perform biological organic oxidation. However, aerobic processes require mechanical aeration accounting for over 40% of total expenditure of a wastewater facility. Additionally, a global urgency for nutrient (Nitrogen/Phosphorus) removal strategies due to surges of eutrophication events requires complex MBR configurations. An innovative and cost-effective process was developed with a dual income-stream: high-quality treated effluent and value-added microalgal biomass for several applications. The proposed process involved several integrated components; an ultrafiltration AS-MBR for organic oxidation followed by a microalgal membrane photobioreactor (MPBR) to remove nutrients (N/P) through assimilation while simultaneously photosynthetically generating dissolved oxygen effluent that was recirculated back into the AS-MBR, thereby reducing the need for mechanical aeration for oxidation. A lab-scale system was fed with a synthetic medium-strength municipal wastewater. The microalgal species C. vulgaris was initially tested in batch trials as a proof-of-concept study on its potential as a photosynthetic oxygenator for the AS-MBR and identify its nutrient utilization efficiencies. The MPBR and MBR were later constructed for continuous operation, with the aim to identify an optimal process configuration. The unit processes were subsequently isolated, where the AS-MBR was subjected to a modelled algal effluent to assesses the impact of varying influent characteristics and effluent recycle rates. A microbial community analysis was performed by high-throughput sequencing and a statistical data-driven modeling approach to assess treatment performances. The MPBR stage was then subjected to the effluent achieved by the AS-MBR stage under varying operating conditions to assess its treatment performance and the resulting algal biomass biochemical composition to identify its suitability for bioethanol, biodiesel, or animal feed production. The findings of this study ultimately confirmed the ability of C. vulgaris to support the AS-MBR for organic removal and fractional nutrient removal by supplying the oxygen demand, and further achieve an effluent polish stage for nutrient removal. The process configuration also demonstrated the ability to achieve a high microalgal biomass production with the potential of extracting valuable products as an added benefit of the wastewater treatment.
172

The effect of metformin-induced AMPK activation on adipogenesis and HIV replication

Alexandre, Kabamba Bankoledi 08 April 2008 (has links)
ABSTRACT Metformin is the most common drug used against type 2 diabetes mellitus. However, it was only recently shown, in human and rat hepatocytes, that metformin-like 5-aminoimidazole-4-carboximide ribonucleoside (AICAR), acts via activation of the AMP-activated protein kinase (AMPK), an enzyme that plays a central role in lipid metabolism. Although it is well known that metformin is used in the treatment of type 2 diabetes and results in significant fat loss, no study has investigated the effects of this drug on adipocytes. In this report I studied the effects of metformin on the formation of fat deposits in mouse 3T3-L1 preadipocytes, as well as its effects on the activation of AMPK in these cells. Our results suggested that metformin significantly inhibits the transformation of pre-adipocytes into adipocytes. This is achieved via the inhibition of intracellular lipid accumulation during adipogenesis. In addition to its inhibition of intracellular lipid accumulation, metformin induced a significant increase in the phosphorylation of AMPK. It has been shown that AMPK activation with AICAR results in the inhibition of the nuclear factor-κB (NF-κB) induced gene expression. Since NF-κB is the key nuclear factor used by HIV-1 during the initiation of its gene transcription, I investigated the possibility of inhibiting HIV-1 replication in U1 cells with metformin and AICAR. I observed that AICAR and metformin inhibit HIV-1 replication in U1 cells. This inhibition wasparalleled by the accumulation of NF-κB in the cytoplasm of AICAR and metformin treated cells, and at the same time by a significant decrease in the concentration of this nuclear factor in the nucleus of these cells. However, I failed to observe any phosphorylation of AMPK by metformin and AICAR in U1 cells. In conclusion, metformin inhibits adipogenesis in mouse adipocytes and this inhibition is likely to take place via the activation of AMPK. AICAR and metformin have inhibitory properties against HIV-1 replication. However, this inhibition does not seem to be by the activation of AMPK.
173

Identificação nebulosa da concentração de oxigênio dissolvido do tanque de aeração de uma estação de tratamento de esgotos por lodos ativados.

Rocha, Alexandre Magno Parente da 13 February 2003 (has links)
As estações de tratamento de esgotos por lodos ativados são caracterizadas por modelos cinéticos de comportamento não linear de difícil parametrização. A utilização de técnicas de identificação paramétricas para a modelagem de tais estações produz modelos com parâmetros sem significado operacional e variantes no tempo. Por outro lado, a lógica nebulosa permite ao usuário de modelos baseados em tal técnica uma parametrização mais próxima do raciocínio humano. A facilidade da parametrização nebulosa reside na atribuição de valores lingüísticos às variáveis de entrada do modelo. Esta dissertação utiliza técnicas de modelagem nebulosa, como ANFIS e regras limitadas, para identificar o comportamento da concentração de oxigênio dissolvido do tanque de aeração do benchmark de uma planta de tratamento de esgotos por lodos ativados com remoção de nitrogênio. / Activated sludge wastewater treatment plants are characterized by kinetic models of highly nonlinear behavior, whose time varying parameters are very difficult to calibrate. The use of parametric identification techniques to build models of such plants results in models with parameters without operational meaning. Alternatively, the fuzzy logic enables users of models, which are based on this technique, a parametrization similar to human reasoning. The simplicity of the fuzzy logic consists of the attribution of linguistic labels to the model input variables. This dissertation uses fuzzy logic techniques, such as ANFIS and limited rules, to identify the behavior of the dissolved oxigen in the aeration tank of a benchmark activated sludge wastewater treatment plant, with nitrogen removal.
174

Afsterwe van mikroorganismes teenwoordig in rioolwater in die mariene omgewing / Die-off of micro-organisms present in sewage in the marine environment

Engelbrecht, Johannes Frederik Pieter January 1990 (has links)
Thesis (M.Dip.)--Cape Technikon, 1990 / The die-off in the marine environment of micro-organisms that are present in sewage was investigated. A literature survey was carried out and studies were done in the laboratory, at an offshore outfall and at a surf-zone outfall. In the laboratory raw sewage was mixed with sea water at known dilutions and the die-off of faecal coliforms, faecal streptococci and coliphage was monitored. At the offshore sewage outfall a tracer, Rhodamine B.was released in the pump station and the distribution of the plume around the diffuser was determined by means of the Rhodamine B concentrations and faecal colifonns counts. At the factory surf-zone outlet the Rhodamine B was injected into the pipeline. Samples were taken at 50 and 100 meter distance from the outlet. Thedie-off of faecal colifonns, faecal streptococci and coliphage was monitored. The following results were obtained: Literature study: (i) Coliforms • Temperatures of 15 QC and lower are conducive to survival while nutrients, at a concentration as low as 2,5 mg/L organic carbon, stimulate growth. A rise in salinity has a negative effect on the organisms. • The T90 value in direct sunlight is <2 hours but vanes considerably in the dark (>35 days). Changes in weather• conditions, sunlight intensity, hours of sunlight, depth and turbidity of seawater and different seasons are the most important factors accounting for the variations in the T90 values. • It is, therefore, important for the initial dilution to be large enough. This will ensure that the bacterial counts conform to the water quality criteria, as the die-off rates in the marine environment are slow and not always adequate, except around mid day. • Faecal coliforms as a single parameter is not considered to be the best indicator of marine pollution. • The 1:4 ratio between faecal coliforms and faecal streptococci for human faeces and 1:0,7 ratio for animal waste are not applicable in the marine environment. The survival of faecal streptococci in seawater is better than that of faecal coliforms and the ratio therefore changes. (ii) Enterococci and pathogens • The T90 value for faecal streptococci is double that of coliforms and also varies in the dark. In direct sunlight any change in sunlight intensity, change the T90 values. • In general the numbers of faecal streptococci and pathogens occuring in sewage are smaller than those of coliforms, but their survival time is longer. This could lead to a situation where the water quality complies with the criteria according to the coliform counts, while a health risk may exist due to th survival of pathogens.
175

Remoção de compostos orgânicos causadores de gosto e odor em águas de abastecimento em sistemas pós-filtros adsorvedores de carvão ativado granular. / Removal of taste and odor producing organic substances in water supply in post-filter granular activated carbon adsorber systems.

Ferreira, Carolina Alves de Souza 13 November 2009 (has links)
O objetivo desta pesquisa foi o de estudar o desempenho de pós-filtros adsorvedores de carvão ativado granular de origem mineral e de origem vegetal, com relação a, principalmente, remoção de 2-metilisoborneol e trans-1,10-dimetiltrans- 9-decalol. Os ensaios experimentais foram conduzidos na estação de tratamento de água Alto da Boa Vista, empregando-se quatro filtros piloto em acrílico com diâmetro interno de 14,2 cm e 1,5 m de profundidade de meio filtrante cada, sendo dois deles preenchidos com o carvão ativado granular Filtrasorb 300 da CALGON (filtros 1 e 3) e os outros dois, com o carvão ativado granular 119 12x25 da CARBOMAFRA (filtros 2 e 4). Os filtros operaram em paralelo, 24 h por dia, 7 dias por semana, sendo o 3 e 4 abastecidos com água filtrada da estação; e o 1 e 2, com água filtrada ozonizada. A taxa média de aplicação nos filtros durante os ensaios foi de 143 m3m2.d, o que gerou um tempo de contato no leito vazio médio de 15 min. O tempo médio total de detenção nas colunas de ozonização ficou em 21 min e a dosagem média total de ozônio aplicada na água filtrada da estação em 1,11 mgL. Os valores de 2-metilisoborneol na água filtrada da estação de tratamento foram superiores aos da água ozonizada, indicando que a ozonização contribuiu para a redução (média de 53,4 %) deste composto. O filtro que apresentou os menores valores de 2-metilisoborneol foi o do carvão betuminoso, alimentado com água ozonizada (filtro 1), com uma remoção média de 50,6 %. Além disso, foi o único filtro que apresentou valores médios de 2-metilisoborneol abaixo da concentração limiar de odor ( 9,0 ngL). O filtro que apresentou os maiores valores de 2-metilisoborneol foi o 4 (carvão vegetal alimentado com água filtrada da estação). / The main purpose of this research was to study the performance of granular activated carbon post filter adsorbers made of bituminous coal and vegetal coal (coconut), regarding, mainly, removal of 2-methylisoborneol and trans-1,10-dimethyltrans- 9-decalol. The experimental researches were conducted in the water treatment plant Alto da Boa Vista, using four pilot filters, made in acrylic, with an internal diameter of 14.2 cm and a filter media depth of 1.5 m, each. Two of them (named 1 and 3) were filled with the carbon Filtrasorb 300 (CALGON) and the other two (named 2 and 4), with the carbon 119 12x25 (CARBOMAFRA). The filters operated in parallel, 24 h per day, 7 days per week. The filters 3 and 4 were fed with filtered water from the plant and the filters 1 and 2, with filtered plus ozonated water. The average hydraulic loading rate in the filters was 143 m3m2.d and the empty bed contact time, 15 min. The average detention time in the ozone contact columns was 21 min and the average ozone dosage, 1.11 mgL. The 2-methylisoborneol values in the filtered water of the plant were higher than in the ozonated water, which indicates that the ozonation reduced (average of 53.4 %) this substance. The filter that showed the lower values of 2-methylisoborneol was the bituminous one, fed with ozonated water (filter 1), with an average removal of 50.6 %. Moreover, was the only one that presented average values of 2-methylisoborneol lower than the odor threshold concentration ( 9,0 ngL). The filter that presented the higher values of 2- methylisoborneol was the vegetal one, fed with filtered water (filter 4).
176

Investigação da adição de dosfolat em sistemas de lodos ativados para controle e redução de lodo gerado. / Research of dosfolat addition in activated sludge systems for control and decrease the quantity of produced sludge.

Bertacchi, Marcelo de Castro 15 April 2005 (has links)
Com o objetivo de estudar a redução na geração de resíduos sólidos no processo por lodo ativado por meio de adição química, foi montada uma Estação de Tratamento Piloto na área do Centro Tecnológico de Hidráulica, situado dentro do Campus da Universidade de São Paulo, na cidade de São Paulo. A ETE Piloto é composta de dois sistemas em paralelo, e idênticos, de tratamento por lodo ativado convencional em mistura completa. A pesquisa foi realizada em três fases distintas e consecutivas. Em todas as três etapas, o primeiro sistema de tratamento da ETE Piloto (Sistema I) recebeu a adição do produto Dosfolat XS, com a intenção de verificar se esse provocaria realmente, a redução do lodo gerado, em comparação com o segundo sistema (Sistema II) que não recebeu Dosfolat XS. As três fases da pesquisa consistiram, respectivamente, na operação dos dois sistemas, em paralelo, durante 94, 79 e 133 dias efetivos, com alimentação de esgoto decantado na vazão de 5 m3/dia nas duas primeiras etapas e com esgoto bruto na vazão de 2m3/dia na fase final. Ao longo das três fases do experimento, foram verificadas as condições de sedimentabilidade, as concentrações de sólidos em suspensão totais e voláteis do lodo dos reatores biológicos, e as eficiências de remoção de DBO, DQO, Nitrogênio Total e Fósforo dos dois sistemas paralelos. Os resultados obtidos nessa pesquisa somente indicaram eficiência do produto Dosfolat XS na redução da geração de lodo no tratamento de esgoto por lodo ativado, em relação ao tratamento por lodo ativado sem a adição de Dosfolat XS. / Aiming to study the reduction in waste production in the activated sludge process, a Treatment Pilot Plant was built at Centro Tecnológico de Hidráulica, situated at the campus of Universidade de São Paulo, in São Paulo. The Pilot Plant was composed of two parallel and identical systems, that were operated in the conventional activated sludge process with complete mixing. This study was conducted in three different and successive phases. In each phase, the first system received addition of Dosfolat XS, in order to verify if this product would decrease the quantity of produced sludge, in comparison with the second system, which did not receive any addition. The three phases above mentioned were consisted in the operation of those two systems during 94, 79 and 133 effective days respectively. There was, in the first and second phases, primary effluent feeding at 5m3/day flow and, in the third phase, raw wastewater feeding at 2m3/day. During this three phase experiment, its several parameters were monitored: settleability parameters, total and volatile suspended solids concentration of the sludge in the biologic reactors, and the removal efficiency of BOD, COD, TKN and Phosphorus for those two parallel systems. The results of this study indicated only the efficiency of Dosfolat XS to decrease the quantity of produced sludge in wastewater treated by activated sludge process, in comparison with the activated sludge process without Dosfolat XS addition.
177

Permethrin for Mosquito Control: Drinking Water Impacts and Treatment

Eckert, Lesley 16 December 2013 (has links)
"The goals of this study were (1) to evaluate the impacts of pesticides used for mosquito control on drinking water and (2) to investigate the removal of permethrin from water using activated carbon. A review of current literature on pesticide usage, toxicity, occurrence in the environment, and treatment techniques to remove pesticides from drinking water was conducted. The focus of the literature review was on pesticides used for mosquito control. Permethrin is a synthetic pyrethroid insecticide used extensively in the United States (US) for mosquito control and in agriculture, with approximately 2 million pounds applied each year. Permethrin was selected for investigation based on its widespread use in the US, its inclusion on the Contaminant Candidate List 3 (CCL3), its health hazards, and the lack of previous research on the removal of permethrin from drinking water. The removal of permethrin from water using powdered activated carbon (PAC) was investigated. Equilibrium adsorption experiments to assess removal of cis-, trans-, and total permethrin were conducted using two types of PAC (WPH 650 and WPH 1000). Initial total permethrin concentrations ranged from 2.0 to 4.6 ug/L. PAC doses ranged from 0.0 to 10 mg/L. Results showed that PAC addition is an effective method for removing permethrin from water. Total permethrin concentrations were reduced by 38% with 0.05 mg/L of PAC WPH 650, and reduced to below the detection limit with 3 mg/L of PAC WPH 650. Total permethrin concentrations were reduced by 35% with 0.05 mg/L of PAC WPH 1000 and by 83% with 5 mg/L of PAC WPH 1000. Results for cis- and trans- permethrin were similar. The Freundlich isotherm model provided appropriate fits to the data with an R-squared value of 0.91 for both WPH 650 and WPH 1000."
178

Low Temperature Calorimetry and Alkali-Activated Slags

Freeman, Gregory Edward 29 April 2014 (has links)
The American Society of Civil Engineers’ (ASCE’s) “2013 Report Card for America’s Infrastructure” estimated that “32% of America’s major roads are in poor or mediocre condition.” An estimated $100 billion dollars are needed to maintain that condition, and an additional $79 billion is needed to improve the quality of American roadways to an acceptable level. In many regions around the US, the service lives of concrete pavements are limited by the damage caused by freezing and thawing of pore solution inside the pavements. Alkali-activated slags (AAS) are produced from ground granulated blast furnace slag (GGBFS), a byproduct of iron production, and exhibit cementitious properties. AAS concretes have been shown to have improved corrosion and freeze/thaw resistance compared to traditional cementbased concretes. A Guarded Longitudinal Comparative Calorimeter (GLCC) was used to determine when the freezing and thawing of internal water occurs in three AAS mortars using solutions of NaOH, Na2CO3, or waterglass compared to a control Ordinary Portland Cement (OPC) mortar. AAS mortars using NaOH and Na2CO3 showed comparable thermal properties to the OPC mortar using the GLCC, and the AAS mortar using waterglass was shown to have higher heat capacity compared to the other AAS mixes. The compressive strengths varied by the alkaline solution used, with AAS with Na2CO3 showing inferior compressive strength to OPC, AAS with NaOH showing similar compressive strength to OPC, and AAS with waterglass showing superior compressive strength to OPC, but poor workability. A computer model of the GLCC testing procedure was created and showed good agreement with the experimental data. The GLCC model can be modified to approximate the results of the GLCC using a wider range of materials and internal solutions, like PCMs.
179

Development of a model of the contact stabilization process

Jatko, Joyce Ann January 2010 (has links)
Typescript, etc. / Digitized by Kansas Correctional Industries
180

Performance improvement of an extended aeration treatment plant

Waldo, David F January 2011 (has links)
Digitized by Kansas Correctional Industries

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