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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.
71

Development and characterisation of a WO3-based photoanode for application in a photoelectrocatalytic fuel cell

Todd, Malcolm John. January 2009 (has links)
Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on Oct. 8, 2009). Includes bibliographical references.
72

Ensaios de tratamento de efluentes de indústria de chapa dura de fibra de madeira /

Breda, Carlos César. January 1999 (has links)
Orientador: Paulo Rodolfo Leopoldo / Banca: Jorge de Lucas Junior / Banca: Maria de Lourdes Conte / Resumo: Os efluentes de indústrias de chapa dura de fibra de madeira originários da exploração de eucalipto, são caracterizados por altos valores em DQO e material sólido em suspensão, tornando-os altamente poluentes para o ambiente e, principalmente, para os recursos hídricos. As empresas que atuam nesse segmento fazem o tratamento de seus efluentes de diversas maneiras, sendo a disposição por irrigação em solos cultivados, uma das formas utilizadas. Essa prática tem como base a melhoria da qualidade da água pela sua infiltração e principalmente pela evapotranspiração das plantas. Porém o lançamento em solos tem consequências, às vezes, muito graves, principalmente no que se refere a colmatação do solo e também à possível contaminação do lençol freático. O presente trabalho teve como objetivo o desenvolvimento de um sistema de tratamento de tais efluentes através do processo de peneiramento, visando a remoção das fibras em suspensão. Para isso desenvolveu-se um equipamento composto por peneiras rotativas substituíveis, com base em modelo francês, recomendado para o tratamento de efluentes industriais. Optou-se por esse sistema após a verificação da presença de grande quantidade de material sólido presente no efluente. Foram realizados 5 ensaios combinando-se peneiras rotativas de diferentes malhas (0,25 ; 0,50 ; 0,75 ; 1,00 e 1,50 mm) com suas respectivas rotações (13 ; 20 ; 33 ; 41 e 53 rpm) e vazões de entrada do efluente no sistema, que também foram 5 para cada ensaio. Para se verificar a influência do sistema proposto na redução da carga poluidora do efluente foram coletadas amostras na entrada do sistema (efluente "in natura") e na saída (efluente após peneiramento) totalizando 150 amostras. Nessas amostras foram analisadas as seguintes variáveis: ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The wastewater from hardboard industries coming from the eucalyptus exploration are characterized by high values of COD and suspended solid matter. For this reason, the wastewater significantly pollute the environment, specially the water resources. The industries that act in this area treat their wastewater by different ways. The irrigation of cultivated lands is one of the options for treatment of the wastewater. By using this procedure, there should be an improvement in the water quality because of its infiltration into the soil and because of the plant's evapotranspiration. However, the wastewater irrigation of the soil sometimes brings severe consequences, which are mainly related to the development of crusts on the soil surface and the possible contamination of the ground water. The objective of the present research was based on the development of a system to treat such wastewater by using the screening process, in order to remove the fibers in suspension. To do so, it has been developed an equipment that contains rotating changeable screens based on a French model that is recommended for the treatment of industry's wastewater. Five trials have been performed combining rotating screens with different nets (0.25, 0.50, 0.75, 1.00, and 1.50 mm) with their respective rotations (13, 20, 33, 41, and 53 rpm) and also with 5 different flows of the wastewater incoming in the system. In order to verify the influence of the proposed system on the reduction of the pollutant capacity of the wastewater, 150 samples were collected at the inlet of the system ("in natura" wastewater) and at it's outlet (wastewater after screening). From these samples, the following variables have been analyzed: total solids, fixed total solids, volatile total solids, pH, turbidity, electrical conductivity, COD, BOD, and... (Complete abstract click electronic access below) / Mestre
73

Adsorption of N,N-dimethylamine from aqueous solutions by a metal organic framework, MOF – 235

Beltrán-Suito, Rodrigo, Pinedo-Flores, Angela, Bravo-Hualpa, Fabiola, Ramos-Muñoz, Jorge, Sun-Kou, María del Rosario January 2018 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Water-resistant MOF-235 was used to adsorb N,N-dimethylamine (DMA) from aqueous solutions. It was synthesized from terephthalic acid and FeCl3.6H2O under air-free conditions and characterized by its crystalline structure, functional groups and temperature resistance. The kinetic data results were best adjusted to the pseudo-second order model (R2>0.963). The best-fit isotherm, Langmuir model, suggested the adsorption of DMA is localized on homogenously distributed active sites on the surface. This fit was confirmed by the value of β = 1 on the Redlich-Peterson model. Our study suggests that the manipulation of novel materials such as MOF-235 promises new avenues for water treatment solutions. Schematic structure of MOF-235 and its application as adsorbent. / Revisión por pares
74

The destruction of the cyanobacterial toxin microcystin-LR by semiconductor photocatalysis

Cornish, Benjamin J. P. A. January 2000 (has links)
In fresh waters where cyanobacteria (blue-green algae) flourish, dense growths known as blooms occur. Such blooms present a threat to human and animal health as many of these cyanobacteria produce toxins. One such group of toxins are the microcystins which are hepatotoxic resulting in haemoraging and tumour promotion in the liver. There have been several reports of human poisonings resulting from the presence of cyanotoxins in potable waters, some of which have resulted in fatalities. The most frequently cited cyanotoxin in these poisonings has been microcystin-LR, which has prompted the World Health Organisation (WHO) to set a guideline for the recommended safe level of this toxin in drinking water of 1 mgl-1. Removal of microcystin-LR from potable waters has proven to be inefficient using conventional water treatment techniques such as coagualtion, filtration and chemical oxidation using chlorine. While activated carbon adsorption and membrane filtration have been shown to physically remove microcystin-LR from water the toxin is not destroyed. Recently the use of photocatalysis was shown to rapidly degrade microcystin-LR even at high concentrations. The process involves the illumination of a titanium dioxide catalyst with ultraviolet (UV) light to produce highly oxidising hydroxyl radicals in solution. While several researchers have demonstrated the process's effectiveness in degrading the toxin none have determined the fate of the compound, or if the toxicity related to microcystin-LR has been removed. This study was carried out to determine if photocatalytic oxidation of microcystin-LR was suitable as a treatment method for potable water supplies. Analysis of treated toxin samples by high performance liquid chromatography (HPLC) with photo-diode array detection (PDA) and mass spectroscopy established that the toxin was not completely degraded during photocatalysis. A simple toxicity assessment however indicated that by-products were non-toxic. Using the data from this work a proposed pathway for toxin destruction was produced giving the speculative identity of some of the by-products. The use of hydrogen peroxide to enhance UV mediated destruction of microcystin-LR has been previously reported. There have also been reports of the enhancement of photocatalytiC reaction in the presence of this oxidant. The work carried out in this study demonstrated that the destruction of microcystin-LR by photocatalysis was both more rapid and more efficient when hydrogen peroxide was present in the system. The use of a fixed film flow reactor was also investigated for microcystin-LR destruction. While degradation of the toxin occurred it was demonstrated that batch reactors were more efficient as a treatment method. The effectiveness of the photocatalytic process on microcystin-RR, -LW and -LF was also investigated. While destruction of a" the variants occurred during photocatalytic treatment each microcystin demonstrated different rates and efficiencies of photooxidation. It was concluded from this study that photocatalysis is a promising treatment method for the removal of microcystin-LR and other variants from potable waters. Further research however is required to assess if the tumour promoting effects of microcystin-LR are rendered inactive and to determine the behaviour of the toxins degradation in natural water supplies. The study also allowed for speculation as to how the degradation of the toxin occurred during the photocatalytic process.
75

Aplicação da técnica de eletrofloculação no tratamento de efluentes têxteis / Application of the technique of eletrofloculation in the treatment of effluent textile.

Alexandre Andrade Cerqueira 10 April 2006 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A poluição dos corpos dágua proveniente dos efluentes têxteis provoca alterações em ciclos biológicos afetando principalmente a fotossíntese. Além disso, algumas classes de corantes podem ser carcinogênicos e/ou mutagênicos. Devido à dificuldade em se tratar estes efluentes, novas tecnologias têm sido investigadas. Neste contexto, a eletrofloculação surge com uma técnica promissora, devido à sua eficiência e possibilidade de reuso da água. O presente trabalho tem como objetivo estudar a aplicação do processo de eletrofloculação no tratamento de efluentes de uma indústria têxtil. O processo de eletrofloculação foi realizado em um reator de batelada utilizando eletrodos de ferro e alumínio. A influência dos seguintes parâmetros foi avaliada: natureza e distância do eletrodo, variação de pH, potencial elétrico aplicado e tempo de operação. Os resultados obtidos indicaram que o processo de eletrofloculação nas condições operacionais estudadas é uma alternativa tecnicamente viável para a remoção de DQO, cor e turbidez, a qual foi, respectivamente, de 87%, 95% e 100%. / The pollution of the stream waters through textille effluents causes alterations in biological cycles affecting the photosynthesis mainly. Moreover, some class of dyes can be carcinogenic and/or mutagenic. Due to difficulty in treating these effluents new technologies have been investigated. In the present work, electrofloculation appears to be a very promising technique, due to relatively high efficiency and possibility of water reuse. The present work emend has objective to study the application of electrofloculation in the treatment of effluents of a textile industry. The process was carried out in a batch reactor using electrodes either iron or aluminum. The influence of the following parameters was evaluated: nature and distance between electrodes, pH, electric potential applied and operation time. The results indicated that the process of electrofloculation in these operational conditions is a technical viable alternative for the removal of COD, color and turbidity, which were, respectively, of 87%, 95% and 100%.
76

Photocatalytic degradation of atrazine

Allen, David Peter January 1995 (has links)
No description available.
77

Disinfection of swimming pool water

Bullock, Gillian January 2003 (has links)
Results from this study, which has investigated the impact of the treatment technologies of chlorination, ozonation and UV irradiation on pool water quality are reported. The aim of the study was to evaluate the effect of these technologies in an unbiased way using a unique protocol, and to calculate a mass balance across the pool system. Data refer to a protocol based on operation of a 2.2m (cubed) capacity pilot swimming pool, which allows the comparison of technologies applied with reference to the propensity to generate the chlorinated disinfection by-products (DBPs) of chloramines and trihalomethanes (THMs). The protocol makes use of a specially developed body fluid analogue (BFA), containing simulant endogenous organic matter, with a soiling analogue consisting of commercial humic acid (HA). Using this analogue, levels of organic carbon (OC) and chloramines similar to those recorded in real pools have been obtained, along with somewhat lower levels of THMs. Results revealed conventional chlorination leads to steady-state TOC and DBP levels following an equilibrium period of 200-600 hours, with concentration values which are dependent on BFA loading rate. Following equilibration nitrate is the only DBP accumulating in the pool water, accounting for between 4% and 28% of the ammoniacal nitrogen loaded into the pool depending upon the operating conditions (primarily the Cl:N ratio). Both UV irradiation and ozonation, the latter combined with downstream adsorption, provide a similar efficacy in reducing chloramine levels, with their effect on THM and nitrate formation being highly dependent on the pH level and chlorine dose rate. This study builds on previous experimentation by including a more rigorous analysis of ozone-GAC with respect to DBP formation, a unique analysis of UV irradiation and a more comprehensive mass balance calculation of C, Cl and N across the pool. The study has established that no accumulation of carbon takes place in the pool, contrary to postulations made in previous published studies, and that the balance between the chloramines and THM DBPs is significantly affected by the HA loading.
78

Process options for the treatment of humic rich waters

Fearing, David Andrew January 2004 (has links)
Seasonal periods of high rainfall have led to difficulties in removing sufficient natural organic matter (NOM) to meet trihalomethane (THM) standards, and hence better or alternative treatments are required. Typically bulk water parameters such as dissolved organic carbon (DOC) and UV absorbance at 254nm (UV254) are used to optimise treatment processes. Here the isolated fraction character and molecular weight (MW) distribution was used in conjunction with bulk water parameters to tailor process options for the treatment of humic rich waters. Three options for the removal of NOM were proposed. A staged coagulation based on the optimisation of isolated fractions. The results showed that although no significant reduction in DOC or UV254 was observed filter breakthrough was significantly reduced. Secondly a novel magnetic ion exchange process (MIEX®) for the removal of NOM was evaluated. The results showed that a combination of MIEX® and ferric reduced the THM formation potential (THMFP) by more than 50% and lower MW compounds that are known to be untreated by conventional coagulation were reduced. This option was also shown to be the most robust option for the treatment of waters with differing quality caused by seasonal changes and different catchments. Finally the addition of a range of adsorbents including carbons, hydroxides and clays to both the raw water and the isolated low MW fractions showed that an increase in DOC and UV254 removal was achievable. This was proposed as a post coagulation option during times of high organic loading. All processes provide viable options for the treatment of humic rich waters during times when current processes are being challenged and having difficulty meeting THM standards.
79

Uppströmsarbete i Bergaindustriområde, Kalmar : Spårning av utsläppskällor av koppar, zink, silver ochkadmium via avloppsanalys i ett industriområde

Egilsson, Snorri Jökull, Cornelia, Magnås January 2018 (has links)
Avloppsreningsverket Kalmar vatten AB arbetar med att minska halter av kadmium, silver, koppar och zink som kommer in till verket. Berga industriområde i Kalmar uppskattas som en möjlig källa för metallutsläpp. I det här projektet undersöks avloppsvattnet i delar av Berga för att se om det finns utsläpp av förhöjda metallkoncentrationer. Provtagning utfördes i utvalda avloppsbrunnar under två veckor. Proverna analyserade både internt inom Linnéuniversitetet med ICP-OES samt externt hos Eurofins med ICP-MS.  Undersökningen visade att tre av fyra provpunkter hade förhöjda koncentrationer av minst en metall. Detta kräver vidare arbete av reningsverket för att identifiera enstaka företag som släpper ut förhöjda halter av metallerna.
80

Estudo hidrodinâmico de floculadores mecanizados aplicados ao tratamento de água

Cestari, Jesus Leonardo [UNESP] 08 April 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:29:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-04-08Bitstream added on 2014-06-13T19:59:02Z : No. of bitstreams: 1 cestari_jl_me_ilha.pdf: 749272 bytes, checksum: 806535e7789d2b8561b9f26df18476ef (MD5) / Utilizando-se um floculador mecanizado com quatro câmaras foram realizados ensaios hidrodinâmicos com o traçador cloreto de sódio obtendo-se curvas de distribuição dos tempos de residência (DTR) e os tempos de residência médios para os tempos de residência teórico de 29,54 min, 22,15 min e 14,77 min respectivamente para o floculador operando com 04, 03 e 02 câmaras. Entre as câmaras de floculação havia quatro diferentes posições de passagens, sendo duas em cima “D” e “E” (respectivamente Direita superior e Esquerda superior) e duas embaixo “d” e “e” (respectivamente direita inferior e esquerda inferior). Levando-se em consideração que a entrada de água era realizada na passagem “e”, foram combinadas quatro configurações de passagem para floculador de 04 câmaras (eEeEe , eDeDe , edede e eeeee) e uma quinta empregando-se anteparos (e/e/e/e/e). As mesmas configurações foram estendidas ao floculador operando com 03 e 02 câmaras. Procurou-se avaliar nos floculadores, operando sob as diferentes configurações de passagem apresentadas acima, a magnitude dos efeitos dos curtos-circuitos de acordo com os estudos pré- definidos. Tais estudos combinaram o sentido de rotação dos agitadores (sentido alternado e mesmo sentido de rotação ao longo das câmaras) com a constância ou a variação do gradiente de floculação, além de um estudo com os agitadores desligados. Observou-se, após a análise das curvas DTR, que as configurações edede e e/e/e/e/e para floculador de 04 câmaras, estendidas aos floculadores de 03 e 02 câmaras, apresentaram menor incidência de curtos-circuitos que a configuração eEeEe. A colocação do anteparo que gerou a configuração e/e/e/e/e para floculador de 04 câmaras, estendida aos floculadores de 03 e 02 câmaras, mostrou-se uma alternativa... / Using a mechanical flocculator with four flocculation chambers, hydrodynamic tests were conducted using sodium chloride as a tracer resulting in curves of the residence time distribution (RTD) and the mean residence times for the theoretical residence time of 29.54 min, 22.15 min and 14.77 minutes, respectively for the flocculator with 04, 03 and 02 chambers. Between the flocculation chambers had four different positions of passages, two on top D and E (respectively upper right and upper left) and two down d and e (respectively lower right and lower left). Taking into account that the entry of water has always been held in the lower left passage “e” for the flocculator with 04 chambers, four different configurations were combined (eEeEe, eDeDe, edede and eeeee) and a fifth employing shields (e/e/e/e/e). The same settings were extended to the flocculator operating with three and two chambers. Was evaluated in flocculation unit, operating under the different configurations of passage, the magnitude of the effects of short circuits according to the studies previously defined. These studies combined the direction of rotation of the agitator with the velocity gradient and a study of the rioters off. Was observed after analysis of the curves RTD, that the settings edede and e/e/e/e/e to flocculators of 04, 03 and 02 chambers, showed a lower incidence of short-circuits that configuration eEeEe. The placement of the bulkhead, which generated the configuration e/e/e/e/e, showcases itself as an efficient alternative only in the absence of agitation, promoted by agitators. Flocculator with 04 chambers, one does not notice the influence of parameters direction of the agitator and the constancy or variation of velocity gradient on the RTD

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