Protein-protein and protein-molecule interactions are complicated phenomena due to the tendency of proteins to change shape and function in response to their environment. Protein aggregation whether onto surfaces or in solution, can pose numerous problems in industry. Surface plasmon resonance (SPR) devices and quartz crystal microbalances (QCM) are two real-time, label free methods that can be used to detect the interactions between molecules on surfaces. These devices often employ self-assembled monolayers (SAMs) to produce specific surfaces for studying protein-protein interactions. The objective of this work was to develop methodologies utilizing SPR to better understand protein-protein and protein-molecule interactions with possible applications in the food and separation industrial sectors. A very well characterized whey protein, β-lactoglobulin (BLG), is used in numerous applications in the food industry. BLG can undergo different types of self-aggregation due changes in external environment factors such as buffer strength, pH or temperature. In this work, a hydrophilic SAM was developed and used to study the interaction and non-specific adsorption of BLG and palmitic acid (PA), a molecule which is known to bind to BLG. It was found that PA tended to reduce BLG conformational changes once on the surface, resulting in a decrease in its surface adhesion. Fluorescent excitation emission matrices (EEM’s) using a novel fluorescence probe technique were utilized to detect protein on the surface as well as conformational changes on the surface of the sensor, although the extent these changes could not be quantified. Another whey protein, α-lactoglobulin (AL), was utilized as a surrogate protein to study the adsorption of colloidal/particulate and protein matter (CPP) extracted from filtration studies of river water. A large fraction of natural organic matter (NOM), the major foulant in membrane based water filtration, is CPP and protein. Understanding the interactions between these components is essential in abating NOM membrane fouling. Several SPR methods were investigated in order to verify the interactions. A mixture of AL and CPP particles in solution prevented the non-specific adsorption of AL to the SAM surface. This change in association was then detected through SPR. Fluorescent EEM’s of the sensor surface verified that CPP and AL bound to the surface. This finding has fundamental significance in the interpretation of NOM-based membrane fouling. To better understand the mechanisms behind non-specific adsorption, a mechanistic mathematical model was developed to describe the adsorption of BLGs onto the hydrophilic SAM. The resulting model performed well in terms of predicting adsorption based on SPR data. The model incorporated the monomer-dimer equilibrium of BLG in solution, highlighting the impact of protein aggregation on non-specific adsorption mechanisms. For future studies, improvement in fluorescent FOP surface scan methodology would help identify different protein/molecules and conformations on the surface.

Most common inorganic foulants in RO processes operating on brackish water are calcium carbonate, calcium sulphate and silica. However, silica fouling is the recovery limiting factor in RO system. Silica chemistry is complex and its degree of fouling strongly depends on the silica solubility and its polymerization under different operating conditions of RO process. In several studies carried out in batch and dynamic tests, the presence of polyvalent cations and supersaturation of silica in solutions were found to be the important factors (apart from pH and temperature) that affected the rate of silica polymerization and its induction period. Agitation did increased silica solubility; however, its effect was negligible in presence of polyvalent cations. Alkalization of water solution by coagulants particularly sodium hydroxide was found suitable for silica removal during pretreatment. The presence of magnesium in solution played a key role in silica removal mostly by the mechanism of adsorption to the metal hydroxide. The options of inline mixing (high agitation) for 5 to 10 minutes and microfiltration before RO were found suitable for silica pretreatment. During dynamic tests, the most dominant mechanism for salt deposition (mostly CaSO4) was particulate type in high concentration water solution; while crystallization fouling was the prevailing mechanism of deposition (mostly CaCO3 and silica) in low concentration solution. Silica showed significant effect on size and shape of inorganic salt crystals during coprecipitation. Moreover, the presence of common antiscalants promoted silica fouling. This important finding recommends an extra caution while using antiscalants in case feed water contains silica to a level that can attain saturation near membrane during RO process. A model was developed to predict the silica fouling index (SFI) based on the experimental data for induction period of silica polymerization. The model takes into account the effect of polyvalent cations and concentration polarization near membrane during RO process. It provides a conservative basis for predicting the maximum silica deposition in RO process at the normal operating conditions. A generalised correlation, which was developed for determination of the mass transfer coefficient in RO process, incorporated the effect of temperature change that is usually not considered in previous correlations. A correlation for reduction of silica content in feed water, down to a safe limit of 15 ppm for RO process, was also formulated and validated by the experimental results.

Thesis (M. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 73-80).

Thesis (master's)--Göteborg University, 1999. / Title from PDF t.p. (viewed on Sept. 25, 2007). At head of title: Tjärno Marine Biological Laboratory. Includes bibliographical references (p. 13-14).

Thesis (master's)--Göteborg University, 1999. / Title from PDF t.p. (viewed on Sept. 25, 2007). At head of title: Tjärno Marine Biological Laboratory. Includes bibliographical references (p. 13-14).

O mercado de biorreatores com membranas (BRMs) têm exibido alto crescimento. Contudo, o fouling diminui o desempenho desses sistemas drasticamente. A aeração promove a mitigação do fouling, mas possui alto custo operacional (de até 70% do total da demanda energética) e é utilizada de forma otimizada apenas 10% das vezes, gerando a necessidade de estudos sobre a hidrodinâmica em BRMs. Ferramentas de dinâmica de fluidos computacional (CFD) são úteis para esse tipo de análise. Um dos primeiros passos para encontrar uma solução apropriada em simulações numéricas é propor uma modelagem correta. Dentre os fenômenos a serem modelados, os efeitos da turbulência são provavelmente um dos mais importantes; porém, nenhum artigo que comparasse predições com base na escolha de modelo de turbulência para simulações de sistemas BRM foi encontrado. Dessa forma, o objetivo desse trabalho foi verificar a importância da escolha do modelo de turbulência para simulações de biorreatores com membranas através de CFD. Para isso, as predições obtidas de velocidade local próxima às superfícies das membranas e de tensão cisalhante nessas superfícies para duas taxas de aeração, 5 e 15 m³/h, empregando dois modelos de turbulência, k-ϵ com funções de parede para alto (aR) e para baixo número de Reynolds (bR) e k-ω SST (Shear Stress Transport) com funções de parede automáticas, na análise de um sistema BRM foram comparadas entre si e com dados experimentais e simulados disponíveis na literatura. Os perfis temporais da velocidade e da tensão cisalhante exibiram alta variabilidade no período das oscilações em certos pontos, exigindo um longo tempo de escoamento para a convergência das variáveis locais. Identificou-se a necessidade de outorgar maior importância à definição do intervalo de tempo de coleta de dados experimentais, de modo a adquirir médias representativas do perfil dinâmico das variáveis e destes perfis serem também analisados para comparações mais definitivas entre resultados de simulações e medições experimentais. As diferenças, entre as medições experimentais da literatura e predições, obtidas pelas simulações deste trabalho foram, no geral, de ordem similar ou menores que as obtidas pelas simulações na literatura. Além disso, maior atenção deve ser dada à escolha da estratégia de modelagem de turbulência, visto que houve alta sensibilidade das predições, que variaram em até 21,6% dependendo dessa escolha. / Membrane bioreactors (MBR) market has been showing high growth rates over recent years. However, membrane fouling drastically reduces MBR overall performance. Aeration promotes fouling mitigation, but at a high operational cost (up to 70% of the MBR energy demand) and it is optimally employed only in 10% of the cases. This created the need of studies focused on MBR hydrodynamic. Computational fluid dynamics (CFD) is a useful tool for hydrodynamic analysis. One of the first steps in finding a proper solution for numerical simulation is proposing a correct modelling. Among the phenomena to be modelled for MBR simulations, turbulence effects are probably one of the most important; nevertheless, no paper comparing the predictions based on the turbulence model choice for MBR simulations was found. In sight of that, this work aimed to verify the relevance of the choice of turbulence model for MBR simulations through CFD. Predictions of local velocities near membranes surfaces and of local shear stress on those surfaces, for two aeration rates (5 and 15 m³/h), employing k-ϵ with wall functions for high (aR) and low (bR) Reynolds number and k-ω SST with automatic wall functions, on the analysis of a MRB system, were compared between each other and with experimental and simulated data available in the literature. The velocity and shear stress temporal profiles showed oscillations with highly variable periods in some points, which required a long process real time to verify the local variables convergence. It was identified the need to give more importance to the definition of the time interval for experimental data collection in order to acquire reliable temporal means; also, one must properly analyze the temporal profiles for more definitive comparisons between predictions and experimental measurements. The differences, between experimental data and predictions, obtained through this work simulations were, in general, of similar order or smaller than the ones reported in the literature. Besides, more attention must be given to the turbulence modelling choices, since the predictions obtained here were highly sensitive to those choices, showing differences up to 21,6% among them.

La production et l’utilisation croissante des nanomatériaux et nanoparticules (NP) dans de nombreux secteurs d’activité conduisent inévitablement à un relargage de NP dans l'environnement et notamment dans les eaux, devenant ainsi une pollution émergente dans le schéma de la production d’eau potable. Les membranes d’ultrafiltration (UF) semblent présenter un réel potentiel de rétention envers les NP du fait de leur taille de pores proche de 20 nm. La filtration de NP fluorescentes de diamètre 100, 10 et 1,5 nm en suspensions, seules ou en mélange, a été étudiée. Les tailles des NP ainsi sélectionnées permettent de travailler avec des dimensions plus grande, plus petite et du même ordre de grandeur que la taille des pores. La considération de la concentration des flux de la filtration en nombre de NP a permis d’estimer le nombre de NP bloquées sur et/ou dans la membrane. Une méthodologie précise et fiable permettant la localisation de ces NP bloquées a été consolidée par une précision de mesure plus importante grâce à une caractérisation multi-échelle. Des profils de pénétration des NP fluorescentes dans la membrane ont été réalisés grâce à une imagerie au Microscope Confocal à Balayage Laser (MCBL). L’application des modèles de colmatage aux données expérimentales a montré une bonne adéquation avec la localisation microscopique des NP et les résultats expérimentaux obtenus. L’influence des conditions opératoires, de la présence de sel et/ou de la polydispersité de la suspension d’alimentation sur l’établissement et la localisation du colmatage a pu être déterminée, notamment grâce à la mise en place de plan d'expérience. / The increasing use of nanotechnologies and nanoparticles (NPs) in many sectors of activities leads to their inevitable discharge in the environment and thus in water. The properties and the toxicity of these NP are still unclear, so that this new pollution have to be considered in drinking water treatment plant. Ultrafiltration (UF) membranes, which have nanometric pore size, present a great potential for NP retention. The mass transport through the UF membrane of fluorescent NP, with size of 100, 10 and 1.5 nm, has been studied. The influence of operating conditions (transmembrane pressure, volumetric concentration factor) have been treated by experimental design. Consideration of the NP concentration in number in each flux thanks to a Nanosight NS300, allowed to estimate the number of NPs blocked on and/or into the membrane. An accurate and reliable methodology allowed the localization of the fouling by Confocal Laser Scanning Microscopy (CLSM). Application of fouling models to experimental data showed good agreement with microscopic NP location. The influence of the operating conditions, the salinity and/or the polydispersity of the feed suspension on the fouling establishment and fouling profile has been studied.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-09-13T12:13:14Z No. of bitstreams: 1 LUCIANO MEDEIROS DE SOUZA - TESE (PPGEP) 2008.pdf: 1622133 bytes, checksum: e718708aa81aa024dab3ad2700717546 (MD5) / Made available in DSpace on 2018-09-13T12:13:14Z (GMT). No. of bitstreams: 1 LUCIANO MEDEIROS DE SOUZA - TESE (PPGEP) 2008.pdf: 1622133 bytes, checksum: e718708aa81aa024dab3ad2700717546 (MD5) Previous issue date: 2008-05-30 / Capes / No processo de produção de soda cáustica, umas das etapas é o resfriamento da solução de hidróxido de sódio. O resfriamento da solução de hidróxido de sódio é feito em uma série de tanques que utilizam água gelada e água de torre de resfriamento para reduzir a temperatura da solução até um valor especificado. Cada tanque é dotado de agitador e serpentina de resfriamento. A água usada para resfriamento escoa no interior das serpentinas em contracorrente. Nos primeiros tanques usa-se água da torre de resfriamento e nos últimos tanques água gelada. Um dos grandes problemas dos processos industriais é a incrustação formada nos equipamentos. No sistema de resfriamento de soda cáustica, incrustações se formam devido à cristalização de sais em torno da serpentina diminuindo o coeficiente global de transferência de calor. Um modelo assintótico em função do tempo para incrustações nos tanques foi ajustado para determinar o melhor momento da limpeza do tanque. Otimizar a limpeza dos tanques em relação ao período de tempo e a escolha do tanque é e minimizar o número de limpezas periódicas são os objetivos deste trabalho. A função objetivo é calculada pelo programa baseado num modelo para a simulação deste sistema de resfriamento com modelo de incrustação assintótica desenvolvido anteriormente para este projeto e integrado a outros subprogramas desenvolvidos em MATLAB que utilizam os algoritmos genéticos para escolherem as melhores soluções para o sistema. A partir dos algoritmos genéticos determinaram-se alguns ótimos locais analisando os valores da temperatura da solução no último tanque e o número de limpezas por dia, assim como efeitos na carga térmica e na diferença de temperatura entre a água de resfriamento e a solução. Com o uso dos algoritmos genéticos está sendo possível encontrar padrões ótimos de limpeza para os tanques. / In the process of caustic soda production, one of the stages is the cooling of the sodium hydroxide solution. The cooling of the sodium hydroxide solution is made in a series of tanks that use frozen water and water of cooling tower to reduce the temperature of the solution until the specified value. Each tank is endowed with agitator and coil of cooling. The cooling water flows in the interior of the coils in countercurrent. The water of cooling tower is used in the first tanks, where as the frozen in the last tanks. One of the great problems of the industrial processes is the fouling formed in the equipment. In the system of caustic soda water cooling of the BRASKEM, fouling if they form due to crystallization of leave around the coil diminishing the global coefficient transference heat. An asymptotic model in function of the time for fouling in the tanks it was adjusted to determine optimum moment where the tank must be clean. To optimize the cleaning of the tanks in relation to the period of time and the choice of the tank is and to minimize the number of periodic cleanings they are the objectives of this work. The objective function is calculated by the program based on a model for the simulation of this system of cooling with developed previously for this project and integrated model of asymptotic fouling function to other subprograms developed in MATLAB that use the genetic algorithms to choose the best solutions for the system. From the genetic algorithms some excellent places had been determined analyzing the values of the temperature of the solution in the last tank and the number of cleaning per day, as well as effect in the thermal load and the difference of temperature enters the water of cooling and the solution. With the use of the genetic algorithms it is being possible to find optimum cleaning schedule for the tanks.

The giant freshwater shrimp, Macrobrachium rosenbergii is a large species of prawn grown extensively in aquaculture settings. A social hierarchy exists within the males of this species, representing three distinct male morphotypes. These male morphotypes differ in their behavior, physiology, and morphology and include the largest blue-clawed males (BC males), moderately- sized orange-clawed males (OC males), and the undifferentiated small-clawed males (SM males). All individuals of this species perform grooming behaviors to rid themselves of body fouling which can impede important functions such as movement, respiration, chemoreception, and reproduction. Grooming behaviors in crustaceans often utilize specialized structures called setae, which aid in the removal of fouling material such as debris, algae, and epibionts. The grooming behaviors of M. rosenbergii were examined in this thesis to better understand the importance of these behaviors. Grooming behaviors were commonly seen among all sexes and morphotypes of M. rosenbergii along with other behaviors such as searching for food/habitat, reproductive attempts, and agonistic interactions (N=94). As a species, there were no differences in the regions of the body groomed in terms of frequency and duration. In general, the most commonly used grooming appendage, the first pereopods, and the antennae were most frequently groomed. The antennae are an important site of chemosensory reception and were likely frequently groomed to maintain this sensory input. The internal sites for respiration, the gills, were groomed for the longest amount of time, indicating the importance of removing fouling from these structures. Of the females and male morphotypes, the largest and most dominant BC males performed the most grooming actions and spent the most time grooming, compared to other individuals within the species. This high grooming time budget (35%) is likely due to their position within the social hierarchy; these males must maintain their body along with the structures which allow them to maintain their dominance such as large chelipeds used in territorial interactions with other males. Grooming behaviors in crustaceans were previously hypothesized as secondary behaviors, only occurring when other behaviors were not prioritized. Results from this study provide further evidence of this hypothesis; although grooming is considered an important behavior to remove fouling and prevent interruptions in functions such as respiration, locomotion, and reproduction, it’s frequency and duration decreases when other behaviors prove more beneficial. Results from this thesis continue to validate the adaptive value of grooming in the changing environmental conditions crustaceans experience on a daily basis. These behaviors remove fouling from the body and promote locomotion, respiration, chemoreception, and reproduction. In addition, shrimps grown in aquaculture settings may experience increased fouling when in grow-out ponds. This increased exposure to fouling organisms and debris may lead to an increased mortality of profitable shrimps. Understanding the fouling pressures and grooming abilities of these shrimps during vulnerable times such as placement in grow-out ponds and intermolt periods may increase yield and profitability for aquaculture farmers.

Le colmatage des membranes reste la principale limitation pour le développement du bioréacteur à membrane (BAM). Dans cette thèse, l'objectif principal se concentre sur les effets des micropolluants pharmaceutiques qui se retrouvent dans les eaux usées domestiques sur le colmatage de la membrane du BAM. Carbamazépine (CBZ), un médicament antiépileptique, a été choisi. Les effets de la CBZ sur le colmatage du BAM ont été étudiés de deux manières: un pic de pollution pour étudier les effets des pics de CBZ à court terme sur le pouvoir colmatant et une pollution continue pour examiner les effets de CBZ à long terme sur le colmatage du BAM. Les résultats ont montré que, pendant 3 heures contact avec CBZ de 100 µg L-1, le pouvoir colmatant des boues activées a augmenté en raison de l'augmentation des protéines de 100-1000 kDa dans le surnageant, ce qui pourrait être complètement retenu par la membrane du BAM et les membranes utilisées dans les essais de filtrabilité. L'augmentation des protéines de 100-1000 kDa dans le surnageant peut probablement être causé par la décomposition bactérienne face aux médicaments. L'effet réduit a été observée pour les boues provenant du BAM fonctionné sous la charge organique plus élevée. Pendant le contact continue, la vitesse du colmatage plus élevée a été observé après l'addition en continu de CBZ dans le BAM (90 µg L-1 dans l'alimentation), qui pourrait être lié à l'augmentation importante des protéines de 10-100 kDa dans le surnageant. Des protéines de 10-100 kDa s’accumulent dans le dépôt de la membrane du BAM, modifient de la structure de dépôt et changent les caractéristiques de rétention de BAM. L'augmentation des protéines de 10-100 kDa a probablement été causée par la réaction de défense des bactéries face en permanence des médicaments. Légère inhibition de l'activité microbienne a été trouvée plusieurs jours après l'addition de la CBZ dans le BAM, puis il a été stabilisé à un certain niveau en raison de l'acclimatation des boues au stress pharmaceutique. Similaire, l'augmentation significative de la concentration en protéine a été observée au début plusieurs jours après l'addition de la CBZ dans le BAM, puis retourne à son niveau initial. Aucun changement significatif de la taille des flocs des boues et de la concentration en polysaccharides dans le surnageant n’a été constaté au cours de la période de contact continu à long terme. Cette étude pourrait contribuer à améliorer la compréhension des interactions complexes entre les micropolluants pharmaceutiques, boues activées et le colmatage du BAM / Membrane fouling still remains the main limitation for the development of membrane bioreactor (MBR). In this thesis, the main objective focuses on the effects of pharmaceutical micropollutants which are frequently found in domestic wastewater on MBR fouling. Carbamazepine (CBZ), an anti-epileptic drug, was chosen in this study due to its occurrence in domestic wastewater and persistency in MBR process. The effects of CBZ on MBR fouling were investigated in two different ways of contact, i.e. short-term peak contact and long-term continuous contact. The results showed that during only 3 hours contact with 100 µg L-1 CBZ, the fouling propensity of the sludge increased due to the increase in 100-1000 kDa protein-like substances in the supernatant, which could be completely retained by the MBR membrane and the membranes used in the filterability tests. The increase of 100-1000 kDa protein-like compounds in the supernatant may probably be caused by the bacterial decay when facing the pharmaceutical stress. Besides, the reduced effect was observed for sludge obtained from MBR operated under higher organic loading rate. During the long-term continuous contact, significantly higher MBR fouling rate was observed after the continuous addition of CBZ in the MBR via the feed (90 µg L-1 CBZ in the feed), which could be related to the significant increase of 10-100 kDa protein-like compounds in the supernatant after addition of CBZ. The 10-100 kDa protein-like compounds could accumulate in the biocake, which was formed on MBR membrane surface, modify the biocake structure and change the retention characteristics of MBR. The increase of 10-100 kDa protein-like compounds was probably caused by the defensive response of bacteria when continuously facing the pharmaceutical stress. Slight inhibition of microbial activity was found several days after addition of CBZ in MBR, and then it was stabilized to some constant level due to the acclimation of sludge to the pharmaceutical stress. Similar, significant increase of protein concentration was observed at the beginning several days after addition of CBZ in MBR, then returned to the initial level. No significant change in sludge floc size and polysaccharide concentration in supernatant was found during the long-term continuous contact period. This study could help to enhance the understanding of complex interactions among pharmaceutical micropollutants, activated sludge and MBR fouling