Un nouveau procédé intensifié de vinification continue avec un mélange de levures S.cerevisiae et Sch.pombe immobilisées dans des billes d’alginate est proposé. A l’échelle laboratoire, l’étude de la teneur en billes et de la configuration du réacteur conduit à l’obtention d’un réacteur de type lit fixe permettant une production de vin en 35 heures. Des validations du procédé aux échelles pilote (170 L) puis industrielle (120 hL) montrent que, en cave, du vin de qualité semblable au témoin est produit en 2 à 3 jours. Une analyse du comportement du réacteur a identifié des raisons de pertes de performances liées à l’hydrodynamique lors du changement d’échelle ainsi que des axes améliorations possibles. Ce procédé permet d’obtenir un vin de qualité maitrisée et un gain de temps de plusieurs semaines / From a batch to another, produced wines are usually different because of the different alcoholic and malolactic fermentation courses. To blend wines quality and continue wine production industrialization, a new continuous process, using Ca-alginate immobilized yeast cells, was developed for red wine-making. Working with a blending of S.cerevisiae and Sch.pombe allowed the regrouping of the alcoholic and malolactic fermentations in a unique step. After testing different reactor set-ups at lab scale, the selected process, a vertical bed reactor, was used in real wine-making conditions, firstly in a pilot reactor (170 L) and then in an industrial one (120 hL). The results showed that continuous wine-making was possible in 2 to 3 days. The wine presented nearly the same sensory profile compared to a classical one. Thanks to the analysis of the reactor behaviour, we were able to explain the efficiency losses linked to the hydrodynamic, observed during the scale-up. This new intensified process enables to obtain a wine with a controlled quality and to save several weeks of production time

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2018-02-23T13:55:59Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2018-01-07 16h04min-MS-TESE Versão FINAL.pdf: 5381905 bytes, checksum: 7dbc7dc9b2123e87817635d09f0f8f0e (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-03-05T20:50:42Z (GMT) No. of bitstreams: 2 2018-01-07 16h04min-MS-TESE Versão FINAL.pdf: 5381905 bytes, checksum: 7dbc7dc9b2123e87817635d09f0f8f0e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-03-05T20:50:42Z (GMT). No. of bitstreams: 2 2018-01-07 16h04min-MS-TESE Versão FINAL.pdf: 5381905 bytes, checksum: 7dbc7dc9b2123e87817635d09f0f8f0e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-10-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A maçã, após sofrer dano mecânico, inclusive após o corte no processamento mínimo, sofre rápida degradação das características físico-químicas e sensoriais, podendo tornar-se inapropriada para o consumo. Neste trabalho estudou-se o efeito do tempo de armazenamento refrigerado de maçã in natura; combinado com o efeito de aplicação de antioxidante e de coberturas comestíveis, imediatamente após o corte para obtenção de fatias em forma de gomo, com epiderme. Maçã cv. ‘Gala’, proveniente de Vacaria, RS, colhida no ano de 2015, selecionada, higienizada, sanitizada, tratada com 1-MCP, e refrigerada (1 °C ± 1 °C e 90 % ± 5 % de UR), conforme procedimento padrão da Empresa RASIP, foi transportada até o laboratório de Fisiologia Pós-colheita da Embrapa Clima Temperado, em Pelotas, RS, e armazenadas in natura, sob refrigeração, por 60 d, 120 d e 180 d. Ao final do armazenamento a maçã foi novamente sanitizada, cortada longitudinalmente em oito fatias, imersa por 1 min em solução de cloreto de cálcio (1,0 % m/v), com ou sem o antioxidante eritorbato de sódio (5,0 % m/v), drenada, e imediatamente imersa por 1 min em solução de fécula de mandioca (3,0 %, m/v), alginato de sódio (2,0 %, m/v) ou quitosana (1,5 %, m/v), para formação da cobertura comestível, e finalmente secagem com ar forçado (4,3 m/s, a 16 °C ± 1 °C e 65 % ± 5 %, por 20 min). A unidade experimental consistiu em oito fatias de maçã colocadas em uma bandeja de polietileno, seladas com camada única de filme de PVC, com espessura de 9 μm, e armazenadas por 0 d, 3 d, 6 d e 9 d, a 4 °C ± 1 °C e 90 % ± 5 % de UR. Após cada período de armazenamento foram avaliadas variáveis físico-químicas e sensoriais, e também atividade enzimática. Empregou-se o teste F (p ≤ 0,05) na análise de variância, o teste DMS (Diferença Mínima Significativa) (p ≤ 0,05) na comparação de médias de tratamento e análise fatorial de correlação entre variáveis. Na fruta in natura observou-se aumento na variável ratio (sólidos solúveis totais / acidez total titulável) ao longo do armazenamento. O efeito do tempo de armazenamento da maçã in natura foi significativo em algumas variáveis físico-químicas, mas sem repercussão na análise sensorial. A aplicação de eritorbato de sódio, combinada com aplicação de 8 fécula de mandioca, proporcionou os melhores resultados, tanto na avaliação sensorial quanto nas características físico-químicas, inclusive no retardamento de escurecimento de polpa. / The apple, following mechanical damage, such as cutting for the production of the minimally processed fruit, undergoes rapid degradation of the physicochemical and sensorial characteristics, and may become inappropriate for consumption. In this work, the effect of refrigerated storage time of fresh apple; combined with the effect of applying antioxidant and edible toppings, immediately after cutting the fruit into eight slices with wedge shape, was studied. Apple cv. 'Gala', from Vacaria, RS, harvested in the year of 2015, selected, sanitized, treated with MCP, and refrigerated (temperature of 1 °C ± 1 °C and relative humidity of 90 % ± 5 %), according to standard procedures used by RASIP Company, was transported to the Postharvest Physiology Laboratory of Embrapa Clima Temperado, in Pelotas, RS, and stored in natura, under refrigeration, for 60 d, 120 d and 180 d. At the end of each period of storage, the apple was re-sanitized, cut longitudinally into eight slices of same size and with wedge shape, immersed for 1 min in calcium chloride solution (1.0% w/v), with or without the antioxidant sodium erythorbate (5.0% w/v), drained, and immediately immersed for 1 min in cassava starch solution (3.0%, w/v), sodium alginate (2.0%, w/v) or chitosan (1.5% w/v), to form the edible cover, and finally dried with forced air (4.3 m / s at 16 ° C ± 1 ° C and 65% ± 5% RH, for 20 min). The experimental unit consisted of eight slices of apple placed in a polyethylene tray, sealed with a single layer of PVC film, 9 μm thick, and stored for 0 d, 3 d, 6 d at 4 °C ± 1 C and 90% ± 5% RH. After each storage period, physicochemical and sensory variables were evaluated, as well as enzymatic activity. The F test (p ≤ 0.05) was used in the analysis of variance, the DMS test (p ≤ 0.05) in the comparison of means of treatment and factorial correlation analysis between variables. In the in natura fruit it was observed an increase in the variable ratio (soluble solids / acidity) throughout the storage. The effect of the storage time of the apple in natura was significant in some physical-chemical variables, but without repercussion in the sensorial analysis. The application of sodium erythorbate, combined with the application of cassava topping, provided the best results, both in 10 the sensorial evaluation and in the physicochemical characteristics, including the delay of darkening of pulp.

Made available in DSpace on 2014-12-17T15:42:13Z (GMT). No. of bitstreams: 1 WilliamGM_DISSERT.pdf: 1986302 bytes, checksum: 71e6a449a8f77e2f64a9c3908ab5410d (MD5) Previous issue date: 2013-07-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / A new self-sustainable film was prepared through the sol-gel modified method, previously employed in our research group; sodium alginate was used as the polymer matrix, along with plasticizer glycerol, doped with titanium dioxide (TiO2) and tungsten trioxide (WO3). By varying WO3 concentration (0,8, 1,6, 2,4 and 3,2 μmol) and keeping TiO2 concentration constant (059 mmol), it was possible to study the contribution of these oxides on the obtained films morphological and electrical properties. Self-sustainable films have analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XDR), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and Electrochemical Impedance Spectroscopy (EIS). By the IR specters, it was possible identify the TiO2, and posteriorly WO3, addition has provided dislocation of alginate characteristics bands to smaller vibrations frequencies indicating an electrostatic interaction between the oxides and the polymer matrix. Diffractograms show predominance of the amorphous phase in the films. SEM, along with EDX, analysis revealed self-sustainable films showed surface with no cracks and relative dispersion of the oxides throughout the polymer matrix. From Impedance analysis, it was observe increasing WO3 concentration to 2,4 μmol provided a reduction of films resistive properties and consequent improvement of conductive properties / Um novo filme autossustent?vel foi preparado, atrav?s do m?todo sol-gel modificado, anteriormente empregado no nosso grupo de pesquisa, utilizando como matriz polim?rica o alginato de s?dio, juntamente com o plastificante glicerol, dopado com di?xido de tit?nio (TiO2) e tri?xido de tungst?nio (WO3). Variando as concentra??es do WO3 (0,8, 1,6, 2,4 e 3,2 μmol), e mantendo constante a concentra??o do TiO2 (0,59 mmol), foi poss?vel estudar a contribui??o destes ?xidos nas propriedades morfol?gicas e el?tricas dos filmes obtidos. Os filmes autossustent?veis foram caracterizados atrav?s das t?cnicas de Espectroscopia de Infravermelho com Transformada de Fourier (FTIR), Difratometria de Raios X (DRX), Microscopia Eletr?nica de Varredura (MEV), Espectroscopia de Raios X por Dispers?o de Energia (EDS) e Espectroscopia de Imped?ncia Eletroqu?mica (EIE). Atrav?s dos espectros de FTIR foi poss?vel identificar que a adi??o do TiO2 e, posteriormente, do WO3 proporciona deslocamento das bandas caracter?sticas do alginato para menores frequ?ncias de vibra??o, indicando uma intera??o eletrost?tica dos ?xidos com a matriz polim?rica. Os difratogramas evidenciaram a predomin?ncia do comportamento amorfo nos filmes. As an?lises de MEV, juntamente com as de EDS, revelaram que os filmes autossustent?veis apresentam uma superf?cie sem trincamento e de relativa dispers?o dos ?xidos ao longo da matriz polim?rica. Atrav?s da EIE observouse que o aumento da concentra??o de WO3 at? 2,4 μmol proporcionou uma redu??o do comportamento resistivo dos filmes, e consequente melhoria em suas propriedades condutoras

Avaliou-se o efeito de tratamentos químicos, revestimentos comestíveis e irradiação na conservação de mamões processados minimamente. Após seleção, lavagem e sanitização, os mamões foram descascados e cortados em meias rodelas, as quais foram submetidas a diferentes tratamentos, embaladas e armazenadas a 5±1°C e 90±2%UR. Os mamões PM foram avaliados após 1, 3, 6, 9, 12 e 15 dias. As análises microbiológicas foram fundamentadas na quantificação de coliformes totais e termotolerantes, bactérias psicrotróficas, bolores e leveduras, assim como na verificação da presença de Salmonella. As avaliações físico-químicas basearam-se na determinação da concentração de CO2 no interior das embalagens, perda de massa, cor, firmeza, sólidos solúv eis, acidez titulável, ratio e pH. As características sensoriais aparência, aroma, sabor e textura foram avaliad as por meio de testes com escala hedônica. No primeiro experimento os tratamentos foram: controle, aldeído cinâmico a 0,1%, cloreto de cálcio a 0,75% e combinação de aldeído cinâmico a 0,1% com cloreto de cálcio a 0,75%. O uso de tratamentos químicos em mamões PM resultou em: maior controle de coliformes totais para os mamões PM tratados com aldeído cinâmico e com a combinação de aldeído cinâmico e cloreto de cálcio; menor concentração de CO2 e maior manutenção da firmeza para mamões PM tratados com a combinação de aldeído cinâmico e cloreto de cálcio; e maior concentração de CO2 para os mamões PM tratados apenas com aldeído cinâmico. A imersão nos tratamentos químicos resultou em maior descoloração da polpa dos mamões PM e redução do teor de sólidos solúveis ao longo do armazenamento. No segundo experimento foram utilizados os tr atamentos: controle, amido de arroz a 3%, alginato de sódio a 0,5% e carboximetilcelulose a 0,25%. O uso desses três tipos de revestimento resultou em maior controle de coliformes totais do que o observado no controle. Mamões PM revestidos com amido de arroz e carboximetilcelulose apresentaram redução e aumento da concentração de CO2, respectivamente. Os mamões PM revestidos apresentaram menores teores de sólidos solúveis e seus valores de pH se tornaram menores após 9 dias de armazenamento refrigerado. O r evestimento com carboximetilcelulose proporcionou maior firmeza da polpa no 15° dia. No terceiro experimento foram utilizados os tratamentos: controle, radiação nas doses de 2kGy e 4kGy. O uso de radiação gama em mamões PM resultou em: maior controle de coliformes totais; menor concentração de CO2 nos mamões PM tratados com 2kGy; maior concentração de CO2 e maior descoloração da polpa nos mamões PM tratados com 4kGy; redução da firmeza nos mamões PM tratados com 2kGy e 4kGy; ligeira redução do teor de sólidos solúveis e pequenas variações da acidez titulável em todos os tratamentos. As características sensoriais dos mamões PM tratados com radiação gama não diferiram significativamente do controle durante os 15 dias de armazenamento / The effect of chemical treatments, edible coatings , and irradiation on fresh-cut papaya conservation was evaluated. After selection, washing, and sanitation the papayas were peeled and cut into half slices, which were submitted to different treatments, packed, and stored at 5±1°C and 90±2%RU. The fresh-cut papayas were evaluated after 1, 3, 6, 9, 12, and 15 days. The microbiological analyses were based on the count of total coliform, thermotolerant and psychrotrophic bacteria, molds and yeasts, as well as on the presence of Salmonella. The physicochemical evaluations were based on the determination of CO2 concentration inside the package, weight loss, color, firmness, soluble solids, titratable acidity, ratio, and pH. The sensory characteristics appearance, aroma, flavor, and texture were evaluated using a hedonic scale. In the first experiment, the treatments tested we re: control, cinnamic aldehyde 0.1%, calcium chloride 0.75%, and the combination of cinnamic aldehyde 0.1% and calcium chloride 0.75%. Using chemical treatments to preserve fresh cut papaya resulted in: higher control of total coliforms in fresh-cut papayas treated with cinnamic aldehyde and with the combination of cinnamic aldehyde and calcium chloride; lower CO2 concentration and increased maintenance of firmness in freshcut papayas treated with the combination of cinnamic aldehyde and calcium chloride; and increased in the CO2 concentration in fresh-cut papayas treated only with cinnamic aldehyde. Immersion in chemical treatments caused higher pulp discoloration and reduction in solu ble solids during storage. In the second experiment, the treatments tested were: control, rice starch 3%, sodium alginate 0.5%, and carboxymethylcellulose 0.25%. The use of these three coatings resulted in higher control of total coliforms compared to the control treatment. The fresh-cut papayas coated with rice starch and carboxymethylcellulose presented reduction and increase in the CO2 concentration, respectively. Coated fresh-cut papayas presented lower soluble solids and pH values were lower after 9 days of cold storage. Carboxymethylcellulose coating increased firmness maintenance at day 15. In the third experiment, the following treatments were used: control, radiation at the doses of 2kGy and 4kGy. The use of Gamma radiation in fresh-cut papaya resulted in: higher control of total coliforms; lower CO2 concentration in fresh-cut treated with 2kGy; increased CO2 concentration and increased pulp discoloration in fresh-cut papayas treated with 4kGy; reduction in firmness in fresh-cut papayas treated with 2kGy and 4kGy; slight reduction in soluble solids and small changes in titratable acidity in all treatments. The sensory characteristics of fresh-cut papayas treated with gamma radiation did not significantly differ from the control during the 15 days of storage

Particles and macromolecular components, including biopolymers (protein and carbohydrate), are viewed as the main foulants in the complex feed submerged membrane filtration systems such as membrane bioreactor (MBR). This work focused on two aspects of fouling in complex fluids: 1- Assessing fouling propensity and mechanisms for various model solutions. 2- Using of two specific solutions modelling biomass found in MBR for a better understanding of the fouling mechanisms in submerged MBR processes. Filtrations were carried out with 0.22 ??m PVDF hollow fibre membrane. Alginate was used as a model for polysaccharide, bovine serum albumin (BSA) as a model for protein, (un)washed yeast and bentonite were representing suspended solid contents. According to the data obtained during this study the fouling propensity of each model solution was classified as follow in a decreasing order: Alginate &gt unwashed yeast &gt washed yeast &gt BSA &gt bentonite for one-component solutions; and Alginate-washed yeast &gt Alginate-BSA &gt Alginate-bentonite &gt Alginate-unwashed yeast for two-component solutions. Introducing the alginate increased the reversible fouling (except BSA). Passive adsorption had a significant effect on fouling of alginate even before the beginning of the filtration. Washed yeast and a mixture of washed yeast + BSA were then used as model solutions to simulate the activated sludge found in MBR. The concentration of washed yeast and BSA used in this study were calculated in order for the characterisations of the two model solution to match (in terms of biopolymer contents) those of MBR biomasses reported in the literature. By rinsing, backwashing and chemical cleaning of the membrane, three fouling layers of upper, intermediate and lower were defined respectively. Results obtained from the analysis of the biopolymers found in the cleaning solutions allow a better understanding of the fouling mechanisms occurring for the two model solutions used in this study: for washed yeast, the lower layer and for washed yeast + BSA , the upper and intermediate layers were found to have relatively high biopolymeric composition. This was explained by higher concentration of solids on the membrane surface and by higher biopolymer interactions when washed yeast was mixed with BSA.

Ce travail de thèse concerne l'étude des propriétés physico-chimiques de capsules millimétriques à cœur liquide possédant une membrane fine d'hydrogel d'alginate. Nous avons dans un premier temps caractérisé le transport de molécules à travers la coque d'hydrogel et estimé le rayon de coupure de cette membrane semi-perméable. De plus, il est possible de limiter la fuite de petits solutés hydrophiles en ajoutant une couche hydrophobe entre le cœur aqueux et la membrane d'alginate. Nous démontrons alors que le temps caractéristique de fuite est déterminé par la géométrie du système (épaisseur de la couche hydrophobe et rayon de la capsule) ainsi que la solubilité et le coefficient de diffusion du soluté dans la phase huileuse. D'autre part, le gonflement d'une capsule soumise à une différence de pression osmotique nous a permis d'identifier les régimes viscoélastique et viscoplastique de la membrane sous étirement. Nous en déduisons un module élastique de l'hydrogel, qui diminue au-delà du seuil de plasticité. A contrario, lors de la compression de capsules, l'hydrogel est concentré par expulsion irréversible de l'eau, ce qui entraîne une rigidification de sa structure. Enfin, nous nous sommes intéressés à l'écoulement d'une suspension concentrée de capsules à coeur huileux dans l'eau. Il existe une friction entre les capsules qu'il est possible de contrôler par ajout de tensioactif. Nous avons donc étudié son rôle dans l'écoulement de capsules dans une constriction de type sablier. Ainsi, nous démontrons que le flux est constant et qu'il ne dépend pas de la friction, mais qu'il est fixé par la taille de l'étranglement. En effet, l'écoulement est uniquement déterminé par l'hydrodynamique en phase fluide dans le col du sablier.

La fonctionnalisation des biomatériaux est une stratégie probante et prometteuse développée pour favoriser l'intégration de biomatériaux dans un organisme vivant. Le dépôt de films multicouches de polyélectrolytes est une méthode de fonctionnalisation de surfaces particulièrement adaptée au recouvrement d'implants. Ces surfaces modifiées pourront ainsi interagir avec leur environnement biologique. Au cours de ce travail de thèse, nous avons développé un nouveau revêtement, à base de composés naturels, capable de recouvrir plusieurs types de surfaces. De plus, ces revêtements originaux peuvent être utilisés pour orienter certains phénomènes cellulaires. Dans la première partie de ce travail de thèse, nous avons mis au point un nouveau système de films multicouches à base de collagène et d'alginate. La réticulation chimique avec la génipine, un agent naturel d'origine végétale (Gardenia Jasminoide), stabilise ces constructions pour une utilisation en conditions physiologiques. Les études d'adhérence et de prolifération de cellules endothéliales humaines ont montré que ces revêtements à base de constituants naturels sont des supports adéquats en vue d'applications biomédicales. Nous avons ensuite déposé des films collagène/alginate sur des implants en titane précédemment recouvert d'un gel microporeux en poly(acide lactique). Nous avons pu montrer que les films collagène/alginate favorisent la prolifération de cellules épithéliales, ce qui permettrait une meilleure intégration des implants. Dans la deuxième partie de notre travail, nous avons développé une technique permettant d'obtenir des revêtements et des membranes à base de films multicouches collagène/alginate ayant des structures fibrillaires orientées. L'alignement fibrillaire s'obtient par simple étirement des substrats élastiques en poly(diméthyl siloxane) (PDMS) sur lesquels sont déposés les revêtements collagène/alginate. La déformation longitudinale du substrat induit un alignement préférentiel des fibrilles de collagène du revêtement. L'étude de l'influence du taux d'étirement sur l'alignement des fibres a montré qu'il était possible de moduler cet alignement. Enfin, nous avons observé que le comportement de différents types cellulaires (fibroblastes et astrocytes) est modifié par l'alignement fibrillaire. On note que les cellules s'alignent dans la même direction que les fibrilles de collagène. A l'évidence, l'organisation fibrillaire du revêtement conditionne la géométrie de l'étalement cellulaire. Les cellules s'allongent lorsque les fibrilles sont alignées. De plus, il apparaît que la direction des divisions cellulaires est guidée par la direction de l'alignement des fibrilles de collagène dans le revêtement étiré. Cela signifie que les cellules sont guidées par les fibrilles de collagène alignées.

Three dimensional printing (3DP) is one of the most important solid freeform fabrication (SFF) methods that can produce any material with desired 3D shape by using suitable powder-binder formulations. It differs from the standard molding operations in that it can produce a complicated shapes by a software driven instrument in a laminated fashion and the cost is lower. This method can be applied in a very wide area including drug release operations, biomaterial production especially for bone fixation, prototype production for all purposes, wound dressing etc. It can also be used in obtaining edible objects by using natural polysaccharides with water based binders. In this study, it is aimed to understand the gelling behaviour of some of the gelling materials, which are alginates, pectins and carageenans, and effect of various factors on the production of confectionary objects by means of 3DP process. Effect of multivalent cations, especially Ca2+ ion, on the gelling behaviour of these materials are investigated. The egg-box structure obtained between the polymer segments increases the water holding capacity of the materials and much more chewy structures can be obtained. The molecular changes are followed by Fourier Transform infrared spectroscopy (FTIR). In 3DP applications, the composition of powder and binder, pH, temperature, relative humidity (RH) and machine parameters are important factors affecting the texture of the final object. The texture of the produced specimens is examined by using a texture analyzer and maximum force values are given as g/cm at failure. Alginate and carrageenans are found to be more effective in obtaining chewy textures with Ca2+ ion content in sugar based matrices and optimization of machine parameters are performed to obtain a higher resolution on the specimens.

The present work was undertaken to develop a composite osmotic distillation (OD) membrane consisting of a thin hydrogel coating on a microporous hydrophobic substrate for the concentration of aqueous feeds containing surface-active agents. The range of OD applications using the hydrophobic membrane alone have been severely limited by the propensity for membrane wet-out when contacted by amphiphilic agents such as oils, fats and detergents. Wet-out allows the feed solution to track freely through the membrane pores with a resulting loss of solutes and a decrease in selectivity. The rationale for the approach taken was based on the hypothesis that the high water selectivity of the hydrophilic coating would maintain good water mass transfer to the underlying hydrophobic substrate but exclude other components including surface-active agents. The first stage of this work involved the identification of potential coating materials and the fabrication and structural characterization of films of these materials to determine their suitability. The second stage involved the development of techniques to facilitate adhesion of the hydrophilic coatings to the hydrophobic substrate, and the testing of the resulting composite membranes for OD performance and resistance to wet-out by surface-active agents. Sodium alginate was selected as the major coating component on the basis of its non-toxicity and its potential for stable hydrogel formation. Structural characterization of noncrosslinked films and films crosslinked using a water-soluble carbodiimide (WSC) was carried out using differential scanning calorimetry (DSC), Fourier Transform infrared spectroscopy (FT-IR) and swelling measurements. Maximum crosslinking through esterification of hydroxyl and carboxylic acid groups on adjacent polymer strands using the film immersion method was achieved with a non-solvent (ethanol) concentration of 60 vol % and a WSC concentration of 100 mM at pH 4. These conditions resulted in a hydrogel with an equilibrium water content of 60 wt %. DSC measurements of noncrosslinked and crosslinked alginate films showed an increase in crystallinity and hence rigidity on crosslinking. Therefore, several coatings were prepared as blends of sodium alginate and amorphous highly flexible carrageenan gum in order to meet the flexibility requirements of a membrane subjected to varying operating pressures in an industrial OD plant. Structural characterization with respect to polymer blend ratio was carried out using scanning electron microscopy (SEM), DSC, X-ray diffraction (XRD). The optimisation for crosslinking conditions was undertaken as for sodium alginate alone. Optimum conditions for film preparation were 20 wt % carrageenan content and a crosslinking medium containing 60 vol % non-solvent (ethanol) and 120 mM WSC at pH 4. These conditions produced a hydrogel with an equilibrium water content of 85 wt %. Two different techniques were employed to anchor the coatings on substrate PTFE membranes. For membranes with a nominal diameter of 0.2 µm, the technique involved surface tension adjustment of the coating solution by ethanol addition in order to enhance penetration of the coating solution meniscus into the substrate pores. This was followed by polymer precipitation by the selective removal of water using OD to provide structural interlocking. T-peel strength measurements showed that this technique resulted in a ten-fold increase in adhesion strength when compared with a coating cast without surface tension adjustments. For membranes with a nominal diameter of 0.1µm, an interfacial bonding agent, myristyltrimethylammonium bromide (MTMA), was used. This technique gave a three-fold increase in adhesion strength relative to that of coating cast without the use of MTMA. The composite membranes were tested in extended OD trials using pure water and feeds containing limonene, the major surface-active components of orange oil. The sodium alginate-carrageenan blend membrane, which was the preferred membrane based on flexibility and water sorption considerations, was also tested against full-cream milk and an industrial detergent, sodium dodecylbenzene sulfonate (DBS). The results indicated that the coatings offered little resistance to water transport and were effective in providing protection against membrane wet-out. Durability trials showed that the composite membranes retained their integrity in water for a minimum of 30 days. Overall, this study has expanded the potential applications of OD to include many important industrial concentration steps that are currently being undertaken by conventional processes with unsatisfactory results. These include the concentration of citrus juices, full-cream milk and nuclear power plant liquid waste. These feeds contain limonene, fats and detergents respectively, all of which wet out unprotected hydrophobic membranes.

Particles and macromolecular components, including biopolymers (protein and carbohydrate), are viewed as the main foulants in the complex feed submerged membrane filtration systems such as membrane bioreactor (MBR). This work focused on two aspects of fouling in complex fluids: 1- Assessing fouling propensity and mechanisms for various model solutions. 2- Using of two specific solutions modelling biomass found in MBR for a better understanding of the fouling mechanisms in submerged MBR processes. Filtrations were carried out with 0.22 ??m PVDF hollow fibre membrane. Alginate was used as a model for polysaccharide, bovine serum albumin (BSA) as a model for protein, (un)washed yeast and bentonite were representing suspended solid contents. According to the data obtained during this study the fouling propensity of each model solution was classified as follow in a decreasing order: Alginate &gt unwashed yeast &gt washed yeast &gt BSA &gt bentonite for one-component solutions; and Alginate-washed yeast &gt Alginate-BSA &gt Alginate-bentonite &gt Alginate-unwashed yeast for two-component solutions. Introducing the alginate increased the reversible fouling (except BSA). Passive adsorption had a significant effect on fouling of alginate even before the beginning of the filtration. Washed yeast and a mixture of washed yeast + BSA were then used as model solutions to simulate the activated sludge found in MBR. The concentration of washed yeast and BSA used in this study were calculated in order for the characterisations of the two model solution to match (in terms of biopolymer contents) those of MBR biomasses reported in the literature. By rinsing, backwashing and chemical cleaning of the membrane, three fouling layers of upper, intermediate and lower were defined respectively. Results obtained from the analysis of the biopolymers found in the cleaning solutions allow a better understanding of the fouling mechanisms occurring for the two model solutions used in this study: for washed yeast, the lower layer and for washed yeast + BSA , the upper and intermediate layers were found to have relatively high biopolymeric composition. This was explained by higher concentration of solids on the membrane surface and by higher biopolymer interactions when washed yeast was mixed with BSA.