Pheroid is a patented system comprising of a unique submicron emulsion type formulation. Pheroid vesicles consist mainly of plant and essential fatty acids and can entrap, transport and deliver pharmacologically active compounds and other useful molecules. The aim of this study was to show that a modulation of components and parameters is necessary to obtain the optimum formula to be used in pharmaceutical preparations. Non-optimal or non-predictable stability properties of emulsions can be limiting for the applications of emulsions (Bjerregaard et al., 2001:23). Careful consideration was given to the apparatus used during the processing along with the ratios of the various components added to the formulation and the storage conditions of the Pheroid vesicles. A preliminary study was performed to optimize the most accurate processing parameters during emulsification. The effect of emulsification rate and time, the temperature of the aqueous phase, the number of days the water phase were gassed, the concentration of the surfactant, cremophor® RH 40, used and the concentration of Vitamin F Ethyl Ester CLR added to the oil phase of the o/w emulsion has been studied. Quantification of the mean particle size, zeta potential, turbidity, pH and current values were used to characterize the emulsions. The samples were characterised after 1, 2, 3, 7, 14, 21 and 28 days of storage. The emulsions were also characterised with confocal laser scanning microscopy (CLSM) to measure the number and size and size distribution of the vesicles. After determination of the processing variables influencing the emulsion stability an accelerated stability test was conducted on a final formula. In the present study, accelerated stability testing employing elevated temperatures and relative humidity were used with good accuracy to predict long-term stability of an o/w emulsion kept at both 5 and 25 OC with 60 % relative humidity and 40 OC with 75 % relative humidity. The results of the stability tests were presented in histograms of the physical properties 24 hours, 1 month, 2 months and 3 months after preparation of the emulsion. It was concluded that Pheroid vesicles demonstrate much potential as a drug delivery system. The high stability of this formula allows its use in a wide variety of applications in the pharmaceutical industry. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

The submarine geomorphology of Goletas Channel - Hardy Bay - Shusharti Bay is a record of environmental change, defined by sediment deposition since the late Pleistocene draped over glacially sculpted physiography. Sea level change, contiguous with waning ice extent at the termination of the Fraser Glaciation, triggered an oceanographic transition within Goletas Channel from a low energy closed embayment to a higher energy open channel environment. Morphologic evidence of lower sea level position is observed from sequence stratigraphy in Hardy Bay and suggests regression to 74 m below present. Stratigraphy also shows a correlation between sea level transgression and turbidity current flows in northwest Goletas Channel, and although triggering mechanisms remain elusive, they are likely related to reworking of glacial sediments concomitant to initial open channel conditions. Holocene sediment accumulation has been highest in southeast Goletas Channel, represented by mud with interstitial gas, and has been reworked by tidal currents into contourite structures. A combination of high-resolution multibeam bathymetry, seismic and core samples are used to study the geomorphology of the region.

Στην παρούσα διπλωματική εργασία εξετάζονται τα χαρακτηριστικά των υποθαλάσσιων αποθέσεων της ερυθράς ιλύος που καλύπτουν τεράστια έκταση του πυθμένα του κεντρικού Κορινθιακού κόλπου και προκύπτουν ως μεταλλευτικό κατάλοιπο της επεξεργασίας βωξιτών για την παραγωγή αλουμινίου. / In the present diplomatic work are examined the characteristics of submarine red mud tailings that cover enormous extent of seabed of central corinthian gulf and result as mining residue of treatment of bauxites for the production of aluminium.

The stainless steel industry is an industry which manufactures one of the most used ma-terials in the world. Even though the vast size of the industry many might not reflect werethe steel comes from when buying their IKEAcutlery etc. But in fact this industry is moreintricate and complex than one might think.During the manufacturing process, the steelgoes through several processes. One of thoseprocesses is done by treating the steel withstrong acid. This chemical process is calledpickling. The pickling process is what createsthe characteristic smooth and shiny surface ofa product made in stainless steel.This thesis is about the development of a testunit that is able to effectively test the ASRA(Acid Sludge Removal Apparatus) filter cloths.The ASRA is a filtration system developed by Scanacon in Stockholm that filtrates and puri-fies acid that is used during the pickling pro-cess of a steel manufacture process. Today, it is complicated, time consuming and dangerous totest and evaluate different filter cloths in orderto find the cloth that provides the best result,since the tests has to be conducted on the realsystems. The aim of this thesis was therefore tosolve these problems. Scanacon wanted to findan alternative solution, that would not includeinteraction with the real filtration system. Theyalso wanted a portable and safe solution. To solve the problem a iterative design pro-cess called RDCD which stands for research, design, create & delivery was developed. Theprocesses was heavily influenced by the CDIO process (Conceive, Design, Implement & Ope-rate). After the research phase was conducted it was decided that a small filter analysis productwould be the best way to solve the problem. The product was then developed one com-ponent at a time. During the project several prototypes and test was created and conductedin order to validate the design.The result is a small filtration unit speciallydesigned to simulate the ASRA system. Theproduct is able to rapidly test various filtercloths in an easy way, without putting the user in harm’s way. After the tests has been perfor-med can the user can identify which cloth that worked the best. The product is small enoughto be possible to be carried in a hard case bag,which in turn affords portability. / Stålindustrin är en industri som tillverkar ettav de mest använda materialen i världen. Trotsindustrins enorma storlek är det kanske intemånga som reflekterar varifrån stålet kommerifrån när man köper exempelvis IKEA bestick.Men faktum är att den här industrin är mycketmer invecklad och komplex än vad man kan tro. Under tillverkningsprocessen går stålet ige-nom flera processer. En av de här processerna genomförs genom att behandla stålet med starksyra. Den kemiska processen kallas för betningoch är det som ger en produkt tillverkad i stålden karaktäristiska lena och glänsande ytan. Den här examensrapporten handlar om ut-vecklandet av en test enhet som effektivt kan testa filter dukarna till ASRA (Acid SludgeRemoval Apparatus) systemet. ASRA systemetär ett filtreringssystem utvecklat av Scanaconi Stockholm som filtrerar och renar syran som används under betningsprocessen vid stål-tillverkning. Idag är det komplicerat, tidskrä-vande och farligt att testa och utvärdera olika filterdukar för att ta reda på vilken duk somger bäst resultat, eftersom att testerna måstegenomföras på de riktiga systemen. Målet fördet här examensarbetet var därför att lösa dehär problemen. Scanacon ville ha en alternativlösning som inte kräver interaktion med deriktiga systemen. De ville också ha en portabeloch säker lösning. För att lösa problemet utvecklades en itera-tiv designprocess kallad RDCD som står för research, design, create & delivery. Processen var tungt influerat av CDIO (Conceive, De-sign, Implement & Operate) processen. Efter att researchfasen var genomförd bestämdesdet att en liten filteranalysatorprodukt var detbästa sättet att lösa problemet på. Produktenutvecklades sedan en komponent i taget. Underprojektets gång har flera prototyper byggts och flera tester genomförts för att validera designen. Resultatet är en liten filtreringsenhet som är specialdesignad för att simulera ASRA syste-met. Produkten kan snabbt testa oliak filterdu-kar på ett enkelt sätt, utan utsätta användaren för fara. Efter att testerna genomförts kananvändaren identifiera vilken duk som funkatbäst. Produkten är tillräckligt liten för att fåplats i en hårdplast väska, vilket ger produktenden efterfrågade portabiliteten.

Les courants de gravité, écoulements issus de la présence d’un contraste de densité dans un fluide ou de la présence de fluides de densités différentes, sont rencontrés dans de nombreuses situations naturelles ou industrielles. Quelques exemples de courants de gravité sont les avalanches, les marées noires et les courants de turbidité. Certains courants de gravité peuvent représenter un danger pour l’homme ou l’environnement, il est donc nécessaire de comprendre et de prédire leur dynamique. Cette thèse a pour objectif d’étudier l’évolution de courants de gravité de masse fixée, et notamment l’influence d’une forme initiale non-axisymétrique sur la dynamique, effet jusque-là peu abordé dans la littérature. Pour cela, une large gamme de paramètres est couverte, incluant le rapport de masse volumique entre le fluide ambiant et le fluide dans le courant, le rapport de forme initiale, la forme de la section horizontale de la colonne de fluide (circulaire, rectangulaire ou en forme de croix), le nombre de Reynolds (couvrant jusqu’à 4 ordres de grandeur) et la nature du fluide lourd (salin ou chargé en particules). Deux campagnes d’expériences ont été menées et complétées par des simulations numériques hautement résolues. Le résultat majeur est que la propagation du courant et le dépôt de particules (lorsque particules il y a) sont fortement influencés par la forme initiale de la colonne de fluide. Dans le cas de la colonne initialement rectangulaire le courant se propage plus vite et dépose plus de particules dans la direction initialement de plus courte dimension. Ce comportement non-axisymétrique est observé dans une large gamme des paramètres étudiés ici. Pourtant les modèles analytiques existants et notamment le modèle dit de boîte (box model) qui prédit avec succès le comportement des courants de gravité/turbidité dans les cas plan et axisymétrique ne sont pas capables de reproduire ce phénomène. C’est pourquoi une extension du box model a été développée ici, et est en mesure de décrire la dynamique de courants de gravité de masse fixée dont la forme initiale est arbitraire. Le cas plus général d'un courant de gravité évoluant sur un plan incliné a été abordé et une dynamique intéressante a été observée. / Gravity currents are buoyancy driven flows that appear in a variety of situations in nature as well as industrial applications. Typical examples include avalanches, oil spills, and turbidity currents. Most naturally occurring gravity currents are catastrophic in nature, and therefore there is a need to understand how these currents advance, the speeds they can attain, and the range they might cover. This dissertation will focus on the short and long term evolution of gravity currents initiated from a finite release. In particular, we will focus attention to hitherto unaddressed effect of the initial shape on the dynamics of gravity currents. A range of parameters is considered, which include the density ratio between the current and the ambient (heavy, light, and Boussinesq currents), the initial height aspect ratio (height/radius), different initial cross-sectional geometries (circular, rectangular, plus-shaped), a wide range of Reynolds numbers covering 4 orders of magnitude, as well as conservative scalar and non-conservative (particle-driven) currents. A large number of experiments have been conducted with the abovementioned parameters, some of these experiments were complemented with highly-resolved direct numerical simulations. The major outcome is that the shape of the spreading current, the speed of propagation, and the final deposition profile (for particle-driven currents) are significantly influenced by the initial geometry, displaying substantial azimuthal variation. Especially for the rectangular cases, the current propagates farther and deposits more particles along the initial minor axis of the rectangular cross section. This behavior pertaining to non-axisymmetric release is robust, in the sense that it is observed for the aforementioned range of parameters, but nonetheless cannot be predicted by current theoretical models such as the box model, which has been proven to work in the context of planar and axisymmetric releases. To that end, we put forth a simple analytical model (an extension to the classical box model), well suited for accurately capturing the evolution of finite volume gravity current releases with arbitrary initial shapes. We further investigate the dynamics of a gravity current resulting from a finite volume release on a sloping boundary where we observe some surprising features.

Correntes de densidade são fluxos gravitacionais gerados pela diferença de densidade entre dois fluidos. Correntes de turbidez fazem parte de uma sub-classificação das correntes de densidade, na qual o fluido mais denso tem, na sua composição, partículas em suspensão. Muitos trabalhos numéricos já estudaram a dinâmica das correntes de turbidez, mas, nenhum dos encontrados aplicou mudanças de relevo concomitantes com a simulação, causadas pela sedimentação das próprias partículas da corrente e nem alterou o relevo após a passagem de cada evento em um domínio tridimensional. O presente trabalho pretende analisar a alteração no relevo de fundo causada por uma corrente de turbidez. No código Incompact3d, as equações de Navier-Stokes, Continuidade e Transporte e Difusão são resolvidas em uma malha cartesiana tridimensional. A condição inicial adotada é a de Lock-Exchange. As simulações realizadas utilizaram Simulação Numérica Direta (DNS). O código utiliza um esquema compacto centrado de sexta ordem, em diferenças finitas, para o esquema espacial, e Adams-Bashfort de terceira ordem para o esquema temporal. A validação do código foi realizada comparando-se com trabalhos experimental e numéricos. A análise das diferentes proporções granulométricas mostrou que quanto maior é a quantidade de material grosso na condição inicial, maior será seu depósito para um dado tempo. Em consequência, mais relevante se torna a consideração da alteração do relevo de fundo. Além disso, quanto maior o fator de compactação do sedimento, maior será o erro de não considerar a atualização de fundo. Os resultados também apontaram que os erros médios ao não considerar a atualização do fundo são da ordem de 4% da massa de depósito em 20 tempos adimensionais, para os parâmetros utilizados. Ao se propagar uma corrente de turbidez sobre o depósito de outra, os erros se mostram menores. / Gravity currents are gravitational fluxes triggered by density di erence between two fluids. A sub-classification of those are turbidity currents, in which the denser fluid is composed by the lighter fluid plus suspended particles. Many papers had shown turbidity currents dynamics, although none of the papers found had applied changes in the simulated topography due to deposit during the own simulation, neither they had altered a 3D domain topography after each flux, applying the changes caused by the previous current. The present dissertation aims to analyse the turbidity current dynamics alteration caused by the influence of its own deposit, altering the topography during the very simulation. The analysis is conducted in a polidispersed turbidity current. The Incompact3d code solves Navier-Stokes, continuity and transport-di usion equation, in a tridimensional cartesian mesh. Lock-exchange was chosen to be the initial condition. Direct Numerical Simulations (DNS) are performed. Sixth order compact finite-di erence schemes are used on the spatial domain, while third order Adams-Bashfort is applied for the temporal evaluation. Comparisons with numerical and experimental papers were performed for code verification. Results showed the coarser the particles on the starting lock-exchange, the higher its deposit is, and the more the terrain will be altered. Nevertheless, the bigger the compacting factor, the bigger the error of not considering bathymetry alteration. Results also point that the average errors of not considering the update are in order of 4% on the mass deposit, after 20 dimensionless times, for the used parameters. When a current propagates over the deposit of a previous one, these errors are smaller.

Orientador: Eloi da Silva Feitosa / Banca: Pietro Ciancaglini / Banca: Rosangela Itri / Banca: João Ruggiero Neto / Banca: Vera Aparecida de Oliveira Tiera / Resumo: Estudos de calorimetria diferencial de varredura (DSC) e fluorescência de estado estacionário da sonda Vermelho do Nilo indicam a formação de vesículas de DODAX (X = Cl- ou Br-) em concentrações de surfactantes tão baixas quanto 10 µM. Estas vesículas foram denominadas microvesículas (µV), cuja Tm diminui monotonicamente com a concentração de DODAX até valores de Tm das vesículas tradicionais preparadas em 1.0 mM do surfactante. O efeito do contra-íon (Br- e Cl-) no comportamento termotrópico de fase das vesículas mistas de DODAB-DODAC foi investigado por DSC, condutimetria e espalhamento dinâmico de luz (DLS). Observou-se que a Tm aumenta sigmoidalmente de 45.8 a 48.9 oC com a fração molar de DODAC (xDODAC), com um ponto de inflexão no ponto eqüimolar. A condutividade e o diâmetro hidrodinâmico das vesículas variam muito pouco com xDODAB, indicando que a densidade superficial de carga das vesículas de DODAX é semelhante entre si, e o efeito do contra íon na Tm de DODAX se deve a interações específicas desses contra-íons na interface das vesículas. Medidas de DSC, fluorescência e turbidez de misturas de DODAB-DDAB indicam que as vesículas de DODAB têm maior afinidade por DDAB do que o oposto, resultando na formação de duas populações de vesículas mistas de DDAB-DODAB, com propriedades distintas. Além disso, medidas de fluorescência mostraram que a presença de pequena quantia de DODAB incorporado nas vesículas de DDAB causa um efeito significante na emissão da sonda devido ao aumento do tamanho das vesículas, sugerido por medidas de turbidez. O estudo dos sistemas DODAB/CnTAB/água na concentração total de surfactante igual a 1,0 e 5,0 mM, variando a concentração de CnTAB, e também mantendo a concentração de DODAB fixa em 1,0 mM, revelou uma forte dependência do comprimento da cadeia de hidrocarbonetos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Differential scanning calorimetry (DSC) and fluorescence of the probe Nile Red studies reveal the formation of DODAX vesicles (X = Br- and Cl-) at surfactant concentrations as low as 10 µM. These vesicles were referred to as microvesicles (mV), whose Tm decreases monotonically with increasing DODAX concentration to the value for the ordinary vesicles at 1 mM. The effect of counterion (Br- and Cl-) on the thermotropic phase behavior of mixed DODAB-DODAC vesicles were investigated by differential scanning calorimetry (DSC), conductimetry and dynamic light scattering (DLS). Tm increases sigmoidally from 45.8 to 48.9 oC with DODAC molar fraction (xDODAC), with an inflection point at the equimolarity. The conductivity and the apparent hydrodynamic diameter vary little with xDODAB, indicating that the surface charge density is similar for DODAX, evidencing that the effect of counterion on Tm is due to the counterion specific interactions. DSC, fluorescence and turbidity measurements indicate a higher affinity of DDAB for DODAB vesicles than the reverse, resulting in two populations of mixed DDAB-DODAB vesicles with different properties. Besides, fluorescence measurements show that the presence of a small amount of DODAB in DDAB vesicles causes a pronounced effect on the Nile Red emission, due to the increase in vesicle size, as suggested from turbidity results. The study of DODAB/CnTAB/água systems at 1.0 and 5.0 total surfactant concentration, and varying CnTAB concentrations with constant 1.0 mM DODAB revealed a strong dependence of the chain length n and relative concentration of the surfactante in the properties of mixed DODAB-CnTAB vesicles. This study allowed analyzing the thermotropic phase behavior containing different amount of DODAB, and the mechanism of vesicle-micelle transition with increasing CnTAB concentration, below and above CMC... (Complete abstract click electronic access below) / Doutor

Correntes de densidade são fluxos gravitacionais gerados pela diferença de densidade entre dois fluidos. Correntes de turbidez fazem parte de uma sub-classificação das correntes de densidade, na qual o fluido mais denso tem, na sua composição, partículas em suspensão. Muitos trabalhos numéricos já estudaram a dinâmica das correntes de turbidez, mas, nenhum dos encontrados aplicou mudanças de relevo concomitantes com a simulação, causadas pela sedimentação das próprias partículas da corrente e nem alterou o relevo após a passagem de cada evento em um domínio tridimensional. O presente trabalho pretende analisar a alteração no relevo de fundo causada por uma corrente de turbidez. No código Incompact3d, as equações de Navier-Stokes, Continuidade e Transporte e Difusão são resolvidas em uma malha cartesiana tridimensional. A condição inicial adotada é a de Lock-Exchange. As simulações realizadas utilizaram Simulação Numérica Direta (DNS). O código utiliza um esquema compacto centrado de sexta ordem, em diferenças finitas, para o esquema espacial, e Adams-Bashfort de terceira ordem para o esquema temporal. A validação do código foi realizada comparando-se com trabalhos experimental e numéricos. A análise das diferentes proporções granulométricas mostrou que quanto maior é a quantidade de material grosso na condição inicial, maior será seu depósito para um dado tempo. Em consequência, mais relevante se torna a consideração da alteração do relevo de fundo. Além disso, quanto maior o fator de compactação do sedimento, maior será o erro de não considerar a atualização de fundo. Os resultados também apontaram que os erros médios ao não considerar a atualização do fundo são da ordem de 4% da massa de depósito em 20 tempos adimensionais, para os parâmetros utilizados. Ao se propagar uma corrente de turbidez sobre o depósito de outra, os erros se mostram menores. / Gravity currents are gravitational fluxes triggered by density di erence between two fluids. A sub-classification of those are turbidity currents, in which the denser fluid is composed by the lighter fluid plus suspended particles. Many papers had shown turbidity currents dynamics, although none of the papers found had applied changes in the simulated topography due to deposit during the own simulation, neither they had altered a 3D domain topography after each flux, applying the changes caused by the previous current. The present dissertation aims to analyse the turbidity current dynamics alteration caused by the influence of its own deposit, altering the topography during the very simulation. The analysis is conducted in a polidispersed turbidity current. The Incompact3d code solves Navier-Stokes, continuity and transport-di usion equation, in a tridimensional cartesian mesh. Lock-exchange was chosen to be the initial condition. Direct Numerical Simulations (DNS) are performed. Sixth order compact finite-di erence schemes are used on the spatial domain, while third order Adams-Bashfort is applied for the temporal evaluation. Comparisons with numerical and experimental papers were performed for code verification. Results showed the coarser the particles on the starting lock-exchange, the higher its deposit is, and the more the terrain will be altered. Nevertheless, the bigger the compacting factor, the bigger the error of not considering bathymetry alteration. Results also point that the average errors of not considering the update are in order of 4% on the mass deposit, after 20 dimensionless times, for the used parameters. When a current propagates over the deposit of a previous one, these errors are smaller.

Diferentes floculantes ecológicos têm sido estudados na literatura para o tratamento de água. Entre tais substâncias, a quitosana e os taninos têm sido utilizados, regularmente, em diversos trabalhos relacionados ao tratamento de água. Neste contexto, o objetivo deste trabalho foi a obtenção de microesferas de quitosana comercial (QTSc) e tanino extraído da casca de Eucalyptus urograndis (TAN), para a utilização piloto no tratamento de água bruta com baixa turbidez (100-110 NTU). Primeiramente, avaliou-se o grau de desacetilação da quitosana comercial (QTSc) e da quitosana na microesfera (QTSm) para a avaliação da porcentagem de grupamentos aminas livres ou desacetiladas. Em seguida, a quitosana desacetilada foi utilizada como matriz na preparação de microesferas empregando duas concentrações de TAN (5,0 e 7,5 % v/v). O material preparado foi caracterizado por FTIR, DRX, MEV e TGA. Os espectros de FTIR apresentaram aumento da intensidade dos picos à medida que havia aumento de concentração de TAN nas microesferas formadas. Os espectros de DRX apresentaram um material amorfo. As micrografias por MEV mostraram que a interação da QTS com o TAN modifica as características superficiais da microesfera provocando mudanças na superfície. As análises de DTA/TGA mostraram que as microesferas preparadas com 0 e 5% apresentaram três estágios de degradação térmica e dois estágios para QTS/TAN 7,5% mostrando que o material com QTS/TAN 7,5% apresenta resistência térmica diferenciada quando comparado ao QTS/TAN 0 e 5%. As microesferas foram avaliadas em ensaios de coagulação/floculação por Jar test no tratamento de água bruta utilizando planejamento fatorial experimental (23) no qual fatores utilizados os paramentos de massa de coagulante de 10 mg e 25 mg, pH=7,0 e pH=8,0 e tempo de decantação de 15 min e 30 min. Os fatores foram avaliados quanto a porcentagem de remoção de turbidez e cor. Os resultados mostraram-se satisfatórios quanto a remoção de turbidez, com mínimo de 51,52 % e máximo de 76,67 % e remoção de cor com mínimo de 42,86 % e máximo de 66,00 %. Os melhores resultados de % remoção foram obtidos quando foram utilizadas as microesferas de QTS/TAN 5% em pH = 8,0 com tempo de decantação de 30 min e massa de coagulante de 25 mg. Os resultados permitiram avaliar as microesferas de QTS/TAN como materiais promissores no tratamento de água. / Different ecological flocculants have been studied in the literature for treatment of water and wastewater. Among such substances, chitosan and tannins have been used regularly in several works related to water treatment. In this context, the aim of this study was to obtain commercial chitosan microspheres (QTSc) and tannin extracted from barks of Eucalyptus urograndis (TAN) for pilot utilization in the treatment of raw water with low turbidity (100-110 NTU). At first degree of deacetylation of both, commercial chitosan (QTSc) and the chitosan microsphere (QTSm) was verified for assessment of degree of deacetylation of amines. Microspheres were prepared at different concentrations of TAN ranging from 0 - 7.5% v/v and then characterized by FTIR, XRD, SEM and DTA/TGA. FTIR showed an increase of peak intensity as increased the concentration of the TAN microspheres formed. XRD presented an amorphous material. SEM micrographs allowed verifying the interaction of chitosan and tannin in the modification of the surface. Analyses of DTA/TGA showed that chitosan microspheres CTS/TAN 0% and 5% exhibited three stages of thermal degradation and two stages were observed for 7.5% CTS/TAN, allowed to conclude that CTS/TAN 7.5% has lower heat resistance compared to CTS/TAN 0 and 5%. The microspheres were evaluated in terms of coagulation/ flocculation assays by Jar test using an experimental factorial design (23). The coagulant mass of 10 mg and 25 mg, pH = 7.0 and pH = 8.0 and settling time of 15 min and 30 min were used as main factors. The factors were assessed for percentage removal of turbidity and color, which gave satisfactory results in the removal of turbidity with a minimum at 51.52% and a maximum at 76.67% and color removal with a minimum at 42.86% and maximum at 66.00%. The best results of were obtained using microspheres CTS/TAN 5% at pH 8.0 and settling time of 30 min and 25 mg of coagulant. Microspheres of CTS/TAN are promising in the treatment of water, but additional studies are necessary for searching the better conditions/results for water treatment.

A dupla filtração pode ser considerada como uma das mais promissoras tecnologias para tratamento de água, estimando-se que grande parte das necessidades de tratamento poderiam ser satisfeitas com o uso desta tecnologia. Alguns aspectos ainda não devidamente esclarecidos até o presente sobre esta tecnologia estão relacionados ao tratamento de água com turbidez elevada. Com a montagem e operação de uma instalação piloto, constituída de dois sistemas de dupla filtração (sistema 1: filtro ascendente de areia grossa e filtro descendente de areia e sistema 2: filtro ascendente de pedregulho e filtro descendente de areia), foi realizada uma investigação experimental com águas de estudo preparadas com caulinita (água tipo I com turbidez em torno de 100 uT e água tipo II com turbidez em torno de 300 uT). A coagulação foi realizada com o sulfato de alumínio, sem o uso de alcalinizante ou de acidificante, para que resultasse potencial zeta próximo de zero. A operação de ambos os sistemas foi efetuada com e sem descargas de fundo intermediárias nos filtros ascendentes, e foram variadas as taxas de filtração em ambos os filtros (de 120 a 240 m&sup3/m&sup2.d nos filtros ascendentes e de 180 a 300 m&sup3/m&sup2.d nos filtros descendentes). Concluiu-se principalmente que os dois sistemas foram capazes de produzir água filtrada com turbidez consistentemente menor que 0,5 uT e que a produção efetiva de água depende da turbidez da água de estudo, das taxas de filtração, da execução das descargas de fundo intermediárias e da carga hidráulica disponível para retenção de sólidos. / Double filtration may be considered one of the most important technologies for water treatment. It has been estimated that most of water treatment can be efficiently achieved with the use of this technology, although some design and operational aspects related to the high turbidity of the influent water have not been fully studied until the present time. A pilot plant was built comprising two double filtration systems (system 1 with an upflow coarse sand filter followed by a downflow fine sand filter; system 2 with an upflow gravel filter followed by a downflow filter identical to that used in system 1). The experimental investigation was carried out using influent waters prepared with kaolin (water type I with turbidity of approximately 100 NTU and water type II with turbidity of approximately 300 NTU). Coagulation was accomplished by using aluminum sulfate (no acid or alkaline products) so that the zeta potential resulted approximately zero. The operation of both systems was carried out with and without intermediate down flushes during the runs. Filtration rates in the filters of both systems varied from 120 to 240 m&sup3/m&sup2.d in the upflow filters and from 180 to 300 m&sup3/m&sup2.d in downflow filters. It was mainly concluded that both systems resulted capable to produce filtered water with turbidity consistently lower than 0.5 NTU and that the net production was related to the influent water turbidity, filtration rates, execution of intermediate down flushes and the hydraulic head provided for solids retention in both filter of each double filtration system.