La thèse est consacrée à l’étude de l’influence de l’aération sur le colmatage demembranes fibres creuses, en application aux bioréacteurs à membranes (BAMs)traitant les eaux usées. Un pilote expérimental permet des expériences de filtrationpar plusieurs faisceaux de fibres creuses immergées, en filtration externe-interne, lacompacité des fibres est proche de la configuration de modules membranairesindustriels. Les fibres ont une surface totale de 1,2 m. Les filtrations sont menéessur une suspension synthétique complexe dont les caractéristiques rhéologiquessont comparables à celles des boues activées de BAM. Les différents paramètresde l’aération testés sont le débit d’air, le lieu d’injection des bulles, et le type debulles injectées (grosses ou fines), pour un flux de filtration constant égalementparamètre d’étude. Pour des conditions d’aération montrant des performances defiltration contrastées, il est effectué la caractérisation locale de la phase gaz parbisonde optique, à l’intérieur des faisceaux de fibres. La rétention gazeuse et lesprofils de vitesse (tant la vitesse moyenne des bulles, que les fluctuations de vitesse)sont mesurés et analysés en fonction des paramètres d’aération. La synthèse des résultats met en évidence deux mécanismes hydrodynamiqueslocaux liés à l’aération, et permettant d’expliquer les performances de filtrationconsidérées. Les perspectives de l’étude proposent des emplacements pour lesaérateurs ce qui pourrait mener à une meilleure utilisation de l’air pour la réductiondu colmatage dans les bioréacteurs à membranes. / This thesis is dedicated to better understand the role of aeration to limit fouling onsubmerged hollow fibers membrane fouling, for wastewater treatment industry. Thisstudy uses an innovative experimental setup to perform outside-in filtrationexperiments thanks to several submerged loose hollow fibers organized in confinedbundles. The total membrane area is about 1.2 m2; the configuration of the bundlesis close to the one found in Membrane Bioreactors (MBRs). A complex synthetic fluidwith rheological characteristics close to MBRs sludge is used. Different aerationconditions such as the air flowrate, the location of the air injection, the type ofbubbles injected (whether they are coarse or fine bubbles injected in the reactor)were tested and membrane performances were analysed under a low or a ratherhigh flux of filtration. In specific aeration conditions showing a different behaviour interm of fouling, local characterization of the dispersed phase in an air and watersystem was undertaken by optical probes. Gas hold up and both mean and rootmean square bubble velocity profiles were determined and analysed regarding thelocation of air injection, the air flowrate and the type of bubbles. This study helps understanding the link between local hydrodynamics and foulingmechanisms and could lead to input for aeration device design and location in orderto decrease operating costs due to aeration in Membrane Bioreactors technology.

Le colmatage membranaire demeure l’un des verrous majeurs des bioréacteurs à membrane (BAM). Ces travaux visent à apporter une contribution à la compréhension de la dynamique de structuration de dépôts complexes formés lors de la filtration frontale de (bio)fluides et son impact sur les performances de filtration. Pour cela, différents outils permettant la mesure in-situ des propriétés structurelles locales des dépôts ont été utilisés de manière à pouvoir relier ces propriétés aux performances globales de filtration. Les propriétés électrocinétiques des dépôts ont également été étudiées. Deux méthodes, l’une optique et l’autre acoustique, ont été utilisées pour caractériser les propriétés structurelles locales des dépôts (épaisseur, cinétique de croissance). Dans un premier temps, les épaisseurs obtenues par les méthodes optiques et acoustiques ont été comparées. Il a été montré que, dans le cas de dépôts peu poreux, les deux méthodes conduisent aux mêmes épaisseurs de dépôts. Dans le cas de dépôts plus poreux, ces deux méthodes permettent l’obtention de données complémentaires à deux niveaux de profondeur différents au sein du dépôt. L’influence des conditions opératoires sur la structuration de dépôts de particules modèles a ensuite été étudiée. Grâce à la méthode optique il a été montré que, quelles que soient les conditions opératoires, il existe une variation temporelle des propriétés du dépôt. De plus, une répartition non homogène du dépôt à la surface de la membrane peut également exister, favorisée par de faibles répulsions entre particules. Enfin, l’applicabilité des différentes méthodes au cas des biofluides issus de BAM a été évaluée. La structure de dépôts complexes constitués lors de la filtration de ces biofluides a ensuite été étudiée. La compressibilité des dépôts, mise en évidence à l’échelle globale par suivi des performances de filtration, a également été observée à l’échelle locale : l’épaisseur du dépôt décroît avec une augmentation de la PTM. De plus, à l’échelle locale, une variabilité spatiale des propriétés du dépôt a été mise en évidence. Afin de contrôler la compressibilité des dépôts l’impact de l’ajout de particules au sein du biofluide a été évalué / Membrane fouling is one of the major drawbacks of membrane bioreactors. This study is thus a contribution to the understanding of the dynamic structuring of complex deposits build-up during dead-end filtration of complex biofluids. Several tools were used to perform in-situ characterization of cake layer structural properties at local scale and to link them to global filtration performances. The electrokinetics properties of the deposit were also investigated. An optical and an acoustic method were used to measure local cake thickness and growth kinetics. The thicknesses given by the two methods were first compared. It was shown that for compact deposits the two different methods lead to the same thickness of the deposit. For more porous deposits, these two methods allow to obtain complementary data at two different depths of the deposits. The influence of operating conditions on cake layer structuring during filtration of modelled particles was evaluated. Using the optical method it was shown that, whatever the operating conditions, the cake structure is not constant in time. Furthermore, a spatial variability of the cake layer thickness might exist especially in the case of weak particle-particle repulsion. Finally, it has been investigated whether the different methods could be applied or not to the case of biofluid filtration. The structural properties of the complex deposits built up during diluted activated sludge filtration were investigated. Cake compressibility was observed at global scale by a monitoring of process performances and was also observed at local scale: cake thickness decreases as TMP increases. Furthermore, at local scale, a spatial variability of deposit structure was found. Particle addition into the biofluid was assessed in order to mitigate compressibility effects

Made available in DSpace on 2016-06-02T19:56:59Z (GMT). No. of bitstreams: 1 6695.pdf: 5587762 bytes, checksum: 18422df241d7678995fda12c8a8bf70f (MD5) Previous issue date: 2015-01-23 / Universidade Federal de Sao Carlos / Human exposure to nanoparticles is increasingly becoming a concern, including in the workplace, due to urban and industrial development and the increasing use of motor vehicles. Filtration using fibrous filters is among the various options that can be used to provide efficient elimination of particles. It is known that there has been little research concerning the removal of nanoparticles using these filtration media. The aim of this study was to characterize, evaluate the efficiency and analyze the influence of filtration area on the efficiencies of the filter media HEPA (high efficiency particulate air), glass, micro-quartz, and polyester (300 g/m2) for the removal of nanoparticles. The filtration area was analyzed because is not possible in general to do the experimental testes in laboratory with large filtration area. The evaluation of the filter media depend on the structure of the filters (fiber diameter, thickness, and permeability), the operating conditions (superficial velocity and filtration area), and the characteristics of the filtered aerosols (density and size distribution). The characterization was used to evaluate the filter media and explain some results. Thickness, fiber diameter and permeability are examples of characterization parameters. The experimental setup was used in experimental tests of permeability and efficiency for the 5.3 and 40.7 cm2 filtration areas. A solution of 5 g/L sodium chloride (NaCl) was used to generate the nanoparticles in the filtration tests and a constant superficial velocity of 0.05 m/s. Particles were counted before and after passing through the filter media at the beginning of filtration using the electrical mobility technique. At the end of the filtration (one hour), the particles were again counted before and after the filters (in triplicate). The permeability constants of the HEPA, glass, and micro-quartz filters were the lower and they are influenced by the filtration area, while a much higher value was obtained for the polyester filter and showed no significant variation using different filtration area. Altogether, all the filter media were highly efficient in removing nanoparticles during approximately 2 hours of filtration, with the exception of the polyester filter, for which the efficiency decreased with increasing particle diameter. / Há uma grande preocupação com a exposição de pessoas às partículas nanométricas presentes no ar, até mesmo no ambiente de trabalho. Isto se deve ao desenvolvimento urbano, industrial e o crescente uso de veículos motorizados. Uma das soluções que vem sendo muito utilizadas ultimamente é o processo de filtração utilizando filtros fibrosos. Como há poucas pesquisas sobre o comportamento desses filtros na remoção de nanopartículas, o objetivo desse estudo foi caracterizar, avaliar a eficiência e verificar se o tamanho da área de filtração influencia no desempenho de meios filtrantes HEPA (High Efficiency Particulate Air Filter), de Vidro, de Micro Quartzo e de Poliéster na remoção de nanopartículas. A área de filtração foi avaliada uma vez que em testes laboratoriais nem sempre são possíveis grandes áreas de filtração para avaliação do desempenho de meios filtrantes. O desempenho de um meio filtrante depende da estrutura dos filtros (espessura, porosidade, diâmetro das fibras), das condições operacionais (velocidade de filtração e área de filtração) e das características do material particulado (densidade, tamanho da partícula e distribuição). A caracterização foi utilizada para avaliar os meios filtrantes e justificar possíveis resultados, entre ela está a espessura, o diâmetro das fibras e a permeabilidade. O sistema experimental foi utilizado tanto para a realização de experimentos de permeabilidade como para experimentos de eficiência com áreas de filtração iguais a 5,3cm2 e 40,7 cm2. Nos testes de eficiência foram utilizados uma solução de 5 g/L de cloreto de sódio para geração de partículas e velocidade constante de 5 cm/s. A contagem das partículas antes e após a passagem pelo meio filtrante era feita em triplicata no tempo zero e também depois de uma hora de filtração utilizando a técnica de mobilidade elétrica. Os meios filtrantes HEPA, de Vidro e de Quartzo apresentaram as menores constantes de permeabilidade e os valores foram ligeiramente influenciados pela área de filtração. Já o filtro de Poliéster foi o mais permeável e não apresentou variação significativa com a área de filtração. De uma forma geral, todos os meios filtrantes foram muito eficientes na remoção de nanopartículas durante duas horas de filtração aproximadamente, com exceção do filtro de Poliéster para o qual a eficiência decaiu com o aumento do tamanho das partículas.

La réutilisation des eaux usées traitées (REUT) constitue une ressource alternative pérenne et à fort potentiel notamment pour les régions soumises à un stress hydrique. L’objectif général de cette thèse est de définir les conditions nécessaires pour garantir la fiabilité d’une filière de traitement tertiaire pour la réutilisation. La première partie s’intéresse aux limites des méthodes de dénombrement des microorganismes indicateurs couramment employées, notamment en lien avec la contamination particulaire des effluents. Les résultats indiquent qu’il existe un risque de sous-estimation par ces méthodes pour de fortes charges en matières en suspension.La désinfection par rayonnement ultraviolet (UV) est souvent employée pour garantir la qualité sanitaire de l’eau distribuée. La deuxième partie de cette thèse vise à comprendre les mécanismes pouvant affecter l’efficacité des UV. Une corrélation linéaire a pu être mise en évidence entre la contamination particulaire des effluents à traiter et la baisse d’efficacité de la désinfection UV, caractérisée d’une part par la diminution de la constante d’inactivation des microorganismes exposés aux UV et d’autre part par le risque d’apparition d’un effet de traîne (fraction de microorganismes insensibles aux UV).La mise en place d’un prétraitement par filtration s’avère donc nécessaire en amont de la désinfection UV. La troisième partie de cette thèse a permis de définir les paramètres opératoires les plus adaptés à l’effluent. Enfin, le contrôle de la qualité sur l’ensemble de la filière est envisagé, avec notamment la démonstration de faisabilité d’un système de surveillance en continu basé sur la spectrométrie UV/Visible. / Wastewater reclamation is an ongoing and promising alternative resource in a context of water stress. In particular, this is a major issue in the Mediterranean region, and its effects tend to be intensified by global warming. The main objective of this PhD thesis is to define the conditions for ensuring the reliability of a tertiary treatment chain for wastewater reclamation. The first part deals with the limits of the methods used in routine for the enumeration of indicator microorganisms, in relation with particulate contamination. The results indicate that there is a risk of underestimation by these methods for high loads of suspended matter.Ultraviolet (UV) disinfection has been used for years to ensure the biological safety of reclaimed water. The second part of this work aims to understand the mechanisms which may affect the efficiency of UV disinfection. A linear relationship has been observed between the particulate contamination of the effluents to be treated and the disinfection efficiency loss, featured on one hand by the decrease of the inactivation constant of the microorganisms and on the other hand by the risk of tailing (UV-resistant fraction among the microorganisms).The implementation of a pre-filtration is thus necessary before UV disinfection. The third part of this work enabled to identify the filtration parameters suited for the effluents to be treated. Finally, quality control on the whole chain is considered, in particular with the demonstration of feasibility of a continuous control system based on UV/Visible spectrometry.

Made available in DSpace on 2014-06-11T19:29:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-08Bitstream added on 2014-06-13T20:59:25Z : No. of bitstreams: 1 tavares_mb_me_ilha.pdf: 4164688 bytes, checksum: eafcc37fd64f73e597d28a376ba04de1 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A Filtração Lenta é um processo de tratamento de água que tem como principal característica a eficiente remoção de patógenos, algas e cianobactérias, as quais nos últimos anos têm-se desenvolvido muito nos reservatórios de abastecimento de água devido à eutrofização causada principalmente pelas atividades antrópicas. As cianobactérias produzem substâncias tóxicas conhecidas como cianotoxinas, que causam problemas gástricos, dermatológicos e toxicológicos nos humanos, além de problemas nas estações de tratamento de água. Apesar da eficiência da Filtração Lenta na remoção destes organismos, ela possui restrições quanto à área necessária aos filtros lentos, quanto ao processo de limpeza destes e dos pré-filtros de pedregulho quando utilizados no tratamento. Esta pesquisa teve então como objetivo desenvolver uma pré-filtração ao filtro lento, através das Colunas Verticais de Pré-Filtração, que fosse eficiente na remoção de parâmetros físico-químicos e bacteriológicos e também no procedimento de limpeza, tornando-o mais rápido e menos dispendioso. Este trabalho foi vinculado ao Programa de Pesquisa em Saneamento Básico (PROSAB) de número 5 do ano de 2007. Para tanto, foi utilizada uma instalação piloto de tratamento de água existente na cidade de Ilha Solteira/SP na qual o processo de tratamento foi o de Filtração em Múltiplas Etapas. Nela foram introduzidas quatro colunas verticais de pré-filtração com taxas diferentes entre si. Foram analisados parâmetros de qualidade de água, o período de desenvolvimento da camada biológica e o tempo de colmatação das unidades filtrantes. Como alguns resultados da pesquisa, foram notificados: a rapidez e facilidade no procedimento de limpeza das colunas, além de necessitarem de limpezas menos freqüentes que os pré-filtros de pedregulho; remoção de cerca de 95% de algas... / Slow filtration is a water treatment process that provides an efficient removal of pathogens, algae and cyanobacteria, which in recent years have been developed in a large amount in water reservoirs due to eutrophication, caused by human habits. The cyanobacteria produces toxic substances known as cyanotoxins, which cause gastric, skin and toxic disorders in humans, as well as problems in water treatment plants. Despite the efficiency of slow sand filtration in removing these bodies, it has restrictions on the required area for slow filters, on their cleaning process or rubble pre-filters cleaning when used in treatment. The objective of this research is developing a pre-filter to filter slowly through vertical columns pre-filtration, which would be efficient in the removal of physical, chemical and bacteriological bodies and also in cleaning process, making it faster and less expensive. This work was linked to the Programa de Pesquisa em Saneamento Básico (PROSAB) of 5th paragraph from the year of 2007. For this, we used an existing pilot plant for water treatment from of Ilha Solteira City - SP in which the process of treatment was Multiple Stages Filtration. Four pre-filtration vertical columns with different rates were introduced. We analyzed parameters of water quality, the period of organic layer development and the filter units clogging time. As some search results have been reported: the speed and ease of the columns cleaning procedure, less requiring of rubble pre-filters frequent cleaning; approximately 95% of algae and cyanobacteria removal by the columns; satisfactory turbidity removal, apparent color and true color, and smaller area required for its installation, because of their vertical shape.

Made available in DSpace on 2014-07-29T15:01:52Z (GMT). No. of bitstreams: 1 dissertacao daniela camplesi.pdf: 1230668 bytes, checksum: 56ed1f54e5e43d735ad2b69bff069adc (MD5) Previous issue date: 2009-12-18 / The present work has evaluated the efficiency of an MSF system for treating supplying water on a pilot scale. A MSF pilot plant was located in the Water Treatment Station (WTS) area in Goianápolis- GO and fed by Sozinha stream. The plant was comprised of a dynamic prefilter (DPF) and a vertical upflowing pre-filter (VUF) in layers, both of them with different granular compositions; a slow sand filter (SSF); and a slow sand filter with activated carbon (SSFAC), which was called SEQ. 1. The second sequence of the trial, SEQ. 2, was comprised of a dynamic pre-filter (DPF) and a slow sand filter (SSF-2). The filtration rates in use were 24 and 48 m3/m2 a day for DPF, 12 e 24 m3/m2. day for APF; 3 e 6 m3/m2. day for SSF and SSFAC. The efficiency was evaluated by analyzing turbidity, apparent color, total suspended solids (TSS), as well as total thermo tolerant coliforms. The following items were evaluated: the filtration rates ranging effect onto the MSF unit trial system efficiencies; the MSF system efficiency comparison to the WTS complete cycling treatment; and the correlations between turbidity, color, and coliforms removals and the TSS removals. The results obtained from the trials have shown that DPF and VUF are important units for microorganisms and solid particles retaining, for it prepares the effluent in order to submit it into slow filtration. They have also shown that they make it possible for the roughing filtration to last longer. Generally put, it presents that the slow filters are significantly and above 90% efficient in removing TSS, color and turbidity, and 99% efficient in removing total coliforms and thermotolerant coliforms in all roughing filtration. After comparing the quality of both the water produced by MSF and the one by the complete cycling WTS, it was noticed that MSF produces water with quality similar to the complete cycling WTS. The range for the filtration rates has had significant influence only in the removal efficiencies of color and turbidity. There isn t correlation among the removals of the parameters color, turbidity, TSS and coliforms but for the correlation among apparent color and true color. The experiment results suggest that MSF technology, when suitably operated, it is a viable system for the treatment of supplying water and produced water with low levels of color, turbidity, TSS and coliforms is that 40% of the samples, provided drinking water under conditions compatible to those established by Decree 518/2004 of the Ministry of Health (BRAZIL, 2004) for human consumption / O presente trabalho avaliou a eficiência de um sistema de FiME no tratamento de águas de abastecimento em escala piloto. A instalação piloto FiME, localizada na área da Estação de Tratamento de Água (ETA) de Goianápolis, GO e alimentada pelo Ribeirão Sozinha, era composta de um pré-filtro dinâmico (PFD), um pré-filtro com escoamento vertical ascendente (PFA) em camadas, ambos com composições granulométricas diferenciadas, um filtro lento de areia (FLA) e um filtro lento de areia com carvão ativado (FLAC) e foi denominada SEQ 1. A SEQ 2 do experimento era constituída de um pré-filtro dinâmico (PFD) e um filtro lento de areia (FLA-2). As taxas de filtração utilizadas foram 24 e 48 m3/m2. dia para PFD, 12 e 24 m3/m2. dia para PFA, 3 e 6 m3/m2. dia para FLA e FLAC. A eficiência foi avaliada por meio das análises de turbidez, cor aparente, sólidos suspensos totais (SST) e coliformes totais e termotolerantes. Foi avaliado também o efeito da variação das taxas de filtração nas eficiências das unidades do sistema FiME, a comparação da eficiência do sistema FiME com o tratamento de ciclo completo da ETA e as correlações entre as remoções de turbidez, cor, coliformes e a remoção de SST. Os resultados obtidos nos experimentos demonstraram que o PFD e PFA são unidades importantes para a retenção de partículas sólidas e microorganismos, preparando o afluente para ser submetido à filtração lenta e possibilitam maior duração das carreiras de filtração. De maneira geral, os filtros lentos apresentaram eficiências significativas e superiores a 90% para remoção de cor, turbidez, SST e 99,9% de eficiência para remoção de coliformes totais e termotolerantes em praticamente todas as carreiras de filtração. Quando comparada a qualidade da água produzida pelo sistema FiME com a ETA de ciclo completo, verificou-se que a FiME produz água com qualidade similar à ETA de ciclo completo. As variações das taxas de filtração influenciaram significativamente nas eficiências de remoção de cor e turbidez. Não há correlação entre as remoções dos parâmetros cor, turbidez, SST e coliformes mas há correlação para cor aparente e cor verdadeira. Os resultados obtidos nos experimentos sugerem que a tecnologia de FiME, quando operada adequadamente, é um sistema viável para o tratamento de águas de abastecimento e produziu água com baixos teores de cor, turbidez, SST e coliformes sendo que em 40% das amostras analisadas, proveu água potável em condições compatíveis às estabelecidas pela Portaria 518/2004 do Ministério da Saúde (BRASIL, 2004) para consumo humano

Les performances de filtration d’un filtre à manche vis-à-vis de particules submicroniques et nanométriques ont été évaluées à l’échelle du laboratoire durant plusieurs cycles de colmatage/décolmatage. La distribution granulométrique des particules (aérosol de combustion) était représentative de celle rencontrée en incinération de nano-déchets en sortie de chambre de combustion à l’échelle du laboratoire. Le filtre à manche opérait en conditions réalistes, représentatives de celles rencontrées dans les lignes de traitement des fumées d’incinération de déchets en termes de température, humidité, vitesse de filtration, présence de réactifs et conditions de décolmatage. Le flux d’air et le filtre à manche étaient chauffés à 150°C, la teneur en eau était de 10-12% (soit 3% d’humidité relative HR), et la vitesse de filtration était fixée à 1,9 cm.s⁻¹. Un mélange de particules de taille submicronique de charbon actif et de bicarbonate de sodium, utilisées dans les lignes de traitement des fumées d’incinération pour l’abattement des dioxines/furanes et des gaz acides, était généré simultanément avec l’aérosol de combustion. L’étude s’est centrée sur les performances de filtration au début de la durée de vie du filtre à manche, avant stabilisation de la perte de charge résiduelle du filtre résultant des précédents cycles de filtration. La perte de charge maximale du filtre était fixée à 150 Pa pour tous les cycles de filtration avant décolmatage par rétro-soufflage à air comprimé. Les performances du filtre à manche ont été évaluées en termes d’évolution de sa perte de charge et de son efficacité de collecte (totale et fractionnelle) au cours des cycles de colmatage/décolmatage. De plus, des études expérimentales et théoriques ont été menées afin d’étudier l’influence de divers paramètres sur les performances de filtration du filtre en configuration manche ou plane, tels que l’humidité de l’air (3% HR versus 0% HR à 150°C), la température (150°C versus 24°C), la vitesse de filtration (1,9 cm.s⁻¹ versus 1,4 cm.s⁻¹) et l’influence de l’injection de réactifs. Les principaux résultats de cette étude sont : (i) importante efficacité de capture des particules du filtre à manche en conditions représentatives des lignes de traitement des fumées d’incinération : efficacité minimale de collecte de 98,5% mesurée pour des particules de taille 74 ± 15 nm (diamètre de mobilité électrique), (ii) influence du gâteau résiduel de particules au début de chaque cycle de filtration sur les performances de traitement, (iii) influence significative de l’humidité de l’air sur la structure du gâteau de particules probablement due à l’augmentation des forces d’adhésion entre les particules en présence d’humidité (150°C – 3% HR soit environ 100 g d’eau par kg d’air sec) ; augmentation plus rapide de la perte de charge du filtre à manche en présence d’humidité (150°C – 3% HR) qu’en conditions d’air sec (150°C – 0% HR). / Filtration performance of a pulse-jet bag filter was evaluated at the laboratory-scale regarding submicronic particles with a nanosized fraction during clogging/unclogging cycles. The particle size distribution was representative to those encountered at the outlet of a nano-waste incineration device at laboratory-scale. The bag filter was operated in conditions as similar as possible to those found in flue gas treatment of waste incineration plants, in terms of temperature, humidity, filtration velocity, injection of sorbent reagents and unclogging conditions. The air flow and the bag filter were heated to 150°C, the water content was maintained in the air flow in the range of 10-12% (3% of relative humidity RH), and filtration velocity throughout the bag filter was fixed at 1.9 cm.s⁻¹. A mixture of submicronic suspended particles of activated carbon and sodium bicarbonate, both used in flue gas treatment systems mainly for the removal of dioxins/furans and acid gases, was generated simultaneously with the aerosol representative of combustion emissions.The study focused on the filtration performance at the beginning of the bag filter’s lifetime filter for the 11 first clogging-unclogging cycles before stabilizing the residual pressure drop reached after pulse-jet unclogging. The maximum pressure drop was set at 150 Pa for all filtration cycles. Once the maximum pressure drop was reached, the filter was unclogged using the pulse-jet system. The performance of the bag filter was evaluated in terms of the evolution of pressure drop, fractional and total particle collection efficiencies, during the clogging/unclogging cycles.Moreover, an experimental and theoretical study was carried out on the influence of different parameters on the filtration performance of bag filter and flat filter, such as influence of humidity (3% RH versus 0% RH at 150°C), temperature (150°C versus 24°C), filtration velocity (1.9 cm.s⁻¹ versus 1.4 cm.s⁻¹) and the influence of the injection of sorbent reagents.The main results of this study are: (i) high collection efficiency of the bag filter in representative conditions of flue gas treatment of waste incineration: minimun particle collection efficiency of 98.5% for particle diameter of 74 ± 15 nm (electrical mobility diameter), (ii) influence of residual particle cake at the beginning of the filtration cycles on the bag filter performance, (iii) significant influence of humidity on the porosity of the particle cake due to the capillary condensation of water between the particles in presence of humidity (150°C - 3% RH i.e. almost 100 g of water per kg of dry air). Faster increase of bag filter pressure drop in presence of humidiy (150°C - 3% RH) as compared to the dry conditions (150°C - 0% RH).

La démarche expérimentale menée dans cette thèse a eu comme objectif l'étude des facteurs qui influent l'efficacité de collecte des médias non-tissés chargés par décharge couronne, utilisés pour la filtration de l'air. Les recherches se sont focalisées sur les techniques faisant appel à la décharge couronne en configuration fil-plan et en configuration triode (électrode duale + grille + plan de masse). L'étude s'est déroulée en trois phases : (1) mise au point de dispositifs expérimentaux pour générer la décharge couronne et mesurer le potentiel électrique à la surface des échantillons chargés ; (2) caractérisation de l'état de charge des médias ; (3) évaluation de l'efficacité de collecte, en corrélation avec les résultats des mesures de charge. La distribution de charges a été plus homogène en configuration triode et le niveau de charge a été meilleur en polarité positive. Le déplacement de l'échantillon dans la zone de décharge électrique permet de mieux uniformiser la distribution de la charge. L'augmentation du courant de décharge et du potentiel de grille permet d'amplifier le niveau de charge des médias, suite à l'intensification du champ électrique moyen entre l'électrode active et le plan de masse (en configuration fil – plan), ou entre la grille et le plan de masse (en configuration triode). L'efficacité de la collecte est meilleure si la charge est uniformément déposée, sous l'action d'un champ électrique plus intense. Elle est plus élevée pour les configurations dites « multicouches » où la captation des particules est améliorée par l'association de plusieurs mécanismes physiques, mettant en jeux des forces électriques et mécaniques. / The experimental approach undertaken in this thesis was aimed at the study of the factors affecting the collection efficiency of nonwoven media charged by corona discharge, used for air filtration. Research was focused on techniques using the corona discharge generated by wire-plane and triode configurations (dual electrode + grid + ground plane). The study was conducted in three phases: (1) development of experimental devices to generate corona discharge and measure the electrical potential on the surface of charged samples; (2) characterization of the electrostatic charge state of the media; (3) evaluation of the collection efficiency, correlated with the results of charge measurements. The charge distribution was more homogeneous in triode configuration and the charge level was higher in positive polarity. The sample movement in the electric discharge zone allowed for more uniform distribution of the charge. The increase of the discharge current and gate voltage amplifies the charge level of the media, due to the intensification of the average electric field between the active electrode and the ground plane (configuration wire - plane) or between the gate and the ground plane (in triode configuration). The collection efficiency is better when the charge is uniformly deposited, under the action of a strong electric field. It is higher for the so-called "multi-layer" configurations where the capture of the particles is improved by the combination of several physical mechanisms, involving electrical and mechanical forces.

Les suspensivores ont la tâche importante de séparer les particules de l'eau. Bien qu'une grande gamme de morphologies existe pour les structures d'alimentation, elles sont pratiquement toutes constituées de rangées de cylindres qui interagissent avec leur environnement fluide. Le mécanisme de capture des particules utilisé dépend des contraintes morphologiques, des besoins énergétiques et des conditions d'écoulement. Comme nos objectifs étaient de comprendre ces relations, nous avons eu recours à des études de comparaison pour interpréter les tendances en nature et pour comprendre les conditions qui provoquent de nouveaux fonctionnements. Nous avons utilisé la dynamique des fluides numérique (computational fluid dynamics, CFD) pour créer des expériences contrôlées et pour simplifier les analyses. Notre première étude démontre que les coûts énergétiques associés au pompage dans les espaces petits sont élevés. De plus, le CFD suggère que les fentes branchiales des ptérobranches sont des structures rudimentaires, d'un ancêtre plus grande. Ce dernier point confirme l'hypothèse qu'un ver se nourrit par filtration tel que l'ancêtre des deuterostomes. Notre deuxième étude détermine la gamme du nombre de Reynolds number critique où la performance d'un filtre de balane change. Quand le Re est très bas, les différences morphologiques n'ont pas un grand effet sur le fonctionnement. Cependant, une pagaie devient une passoire lorsque le Re se trouve entre 1 et 3,5. Le CFD s’est dévoilé être un outil très utile qui a permis d’obtenir des détails sur les microfluides. Ces études montrent comment la morphologie et les dynamiques des fluides interagissent avec la mécanisme de capture ou de structures utilisées, ainsi que comment des petits changements de taille, de forme, ou de vitesse d'écoulement peuvent conduire à un nouveau fonctionnement. / Suspension feeders have the important task of separating particles from the liquid medium surrounding them. Although a wide range of morphologies exist for feeding structures, essentially all consist of arrays of cylinders interacting with their fluid environment. The particle capture mechanism employed depends on morphological constraints, energy requirements, and flow conditions, therefore our objectives were to understand these relationships through comparison studies to interpret trends in nature and to understand the conditions in which novel functioning arises. Our studies used computational fluid dynamics (CFD) to create controlled experiments and to simplify analyses. The first study demonstrates the unfeasibly high energetic costs of pumping in small and medium pharynx sizes of hemichordates, implying the gill pores of pterobranchs are likely vestigial structures from a larger ancestor. This last point further supports the hypothesis of an acorn worm as the ancestor to all deuterostomes. Our second study determined the critical Reynolds number (Re) range where barnacle filters transition from a paddle to a sieve. At very low Re, morphological differences have no major effect on functioning and filters behave as paddles, however, at Re 1 - 3.5, these differences dictate when a paddle becomes a sieve. CFD proved to be a very useful tool for simplifying studies and providing detailed microfluidics. These studies demonstrate how morphology and fluid dynamics interact to dictate the capture mechanisms or appendages employed and how simple changes in size, shape, or flow speed can lead to novel functioning.

Integrated Algae Pond Systems (IAPS) are a derivation of the Oswald designed Algal Integrated Wastewater Pond Systems (AIWPS®) and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. IAPS technology was introduced to South Africa in 1996 and a pilot plant designed and commissioned at the Belmont Valley WWTW in Grahamstown. The system has been in continual use since implementation and affords a secondarily treated water for reclamation according to its design specifications which most closely resemble those of the AIWPS® Advanced Secondary Process developed by Oswald. As a consequence, and as might be expected, while the technology performed well and delivered a final effluent superior to most pond systems deployed in South Africa it was unable to meet The Department of Water Affairs General Standard for nutrient removal and effluent discharge. The work described in this thesis involved the design, construction, and evaluation of several tertiary treatment units (TTU') for incorporation into the IAPS process design. Included were; Maturation Ponds (MP), Slow Sand Filter (SSF) and Rock Filters (RF). Three MP's were constructed in series with a 12 day retention time and operated in parallel with a two-layered SSF and a three-stage RF. Water quality of the effluent emerging from each of these TTU's was monitored over a 10 month period. Significant decreases in the chemical oxygen demand (COD), ammonium-N, phosphate-P, nitrate-N, faecal coliforms (FC) and total coliforms (TC) were achieved by these TTU's. On average, throughout the testing period, water quality was within the statutory limit for discharge to a water course that is not a listed water course, with the exception of the total suspended solids (TSS). The RF was determined as the most suitable TTU for commercial use due to production of a better quality water, smaller footprint, lower construction costs and less maintenance required. From the results of this investigation it is concluded that commercial deployment of IAPS for the treatment of municipal sewage requires the inclusion of a suitable TTU. Furthermore, and based on the findings presented, RF appears most appropriate to ensure that quality of the final effluent meets the standard for discharge.