Dissertations / Theses: 'Membrane filtration'

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Krupp, Armin Ulrich. "Mathematical modelling of membrane filtration." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:ae6dd9e4-a862-4476-a8d9-35156848297f.

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In this thesis, we consider four different problems in membrane filtration, using a different mathematical approach in each instance. We account for the fluid-driven deformation of a filtercake using nonlinear poroelasticity in Chapter 2. By considering feeds with very high and very low particle concentrations, we introduce a quasi-static caking model that provides a suitable approximation to the full model for the physically realistic concentration regimes. We illustrate the agreements and differences between our model and the existing conventional cake-filtration law. In Chapter 3, we introduce a stochastic model for membrane filtration based on the quantised nature of the particles and show how it can be applied for feeds with different particle types and membranes with an interconnected pore structure. This allows us to understand the relation between the effects of clogging on the level of an individual pore and on the macroscopic level of the entire membrane. We conclude by explaining the transition between the discrete and continuous model based on the Fokker--Planck equation. In Chapter 4, we consider the inverse problem of determining the underlying filtration law from the spreading speed of a particle-laden gravity current. We first couple the theory of gravity currents with the stochastic model developed in Chapter~3 to determine a filtration law from a given set of experiments. We then generalise this idea for the porous medium equation, where we show that the position of the front follows a power law for the conventional filtration laws, which allows us to infer the clogging law in certain instances. We conclude the thesis by showing in Chapter 5 how we can combine experimental measurements for the clogging of a depth filter and simple fluid dynamics to accurately predict the pressure distribution in a multi-capsule depth filter during a filtration run.

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Mayor, Russell. "Some problems in filtration." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320650.

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Mignard, Dimitri. "Mass transport studies in membrane filtration." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/12654.

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First, a programme to model concentration polarisation was written using the finite difference approach developed by Ilias and Govind. It was validated with experiments using Centrisystem C-300 and C-400 cartridges and BSA solutions (1-5 g/L), and experimental data from Yeh and Cheng with an H1P30-20 Amicon cartridge and Dextran T-500. The next step was to incorporate fouling into this model. To calculate the configurational Derjaguin-Landau-Vervey-Overbeek (DLVO) forces and the resulting osmotic pressures, large use was made of the work of Bowen et al. Concentration dependent diffusivities were calculated from the generalised Stokes-Einstein equation, and used in the transport equation to describe the concentration polarisation profile. It was shown that, when the transport equation did not have a solution at the membrane (or membrane + cake) surface, and that concentration was greater than the highest-concentration local maximum for the diffusivity, coagulation would occur. In this case, a monolayer of globular protein was assumed to deposit, and concentration polarisation was recalculated with this additional resistance. Experiments with 1g/L BSA solutions and Amicon H1P30-20, for a range of transmembrane pressure, ionic strengths and pH, were compared with the model predictions. Both showed that fouling increased with ionic strength away from the Iso-Electric Point of BSA (IEP), and decreased with zeta potential. Simulation also showed that fouling could decrease with increased ionic strength around the IEP, in accordance with classical results. Total resistance to flux from experiments and simulation were in a similar range, although the lack of data relating zeta potentials and pH prevented further comparison. The model would also determine the critical pressure above which fouling occurred. However, observed values were significantly lower than predicted. Direct adsorption of the BSA onto the polysulfone membrane or the effect of high local pore velocities may both explain these discrepancies.

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Ye, Yun School of Chemical Engineering &amp Industrial Chemistry UNSW. "Macromolecular fouling during membrane filtration of complex fluids." Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/33245.

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Macromolecular components, including protein and polysaccharides, are viewed as one type of major foulants in the complex feed membrane filtration systems such as membrane bioreactor (MBR). In this thesis, the mechanisms of macromolecular fouling including protein and polysaccharide in the complex feed solution are explored by using Bovine serum albumin (BSA) and alginate as model solution. During the filtration of BSA and washed yeast with 0.22 ????m PVDF membrane, it was found that the critical flux of mixture solution was controlled by washed yeast concentration while the existence of BSA significantly changed the cake reversibility of much larger particles. The fouling mechanisms of alginate, as a model polysaccharide solution, were investigated both in dead end and crossflow membrane filtration. In the dead end experiments, it was found that the cake model appears to fit the entire range of the ultrafiltration data while the consecutive standard pore blocking model and cake model are more applicable to microfiltration membranes. The alginate was featured with high specific cake resistance and low compressibility despite some variations between different membranes. The specific cake resistance ( c ) is similar to c of BSA and actual extracellular polymer substance (EPS) in MBR systems reported in the literature, and higher than that of many colloidal particles. In a system contained alginate-particles mixture, it was found that the existence of alginate dramatically increased the cake specific resistance and decreased the cake compressibility. The fouling mechanism of alginate was also studied using long term cross flow filtration under subcritical flux. A two-stage TMP profile similar to that typically observed in MBR was obtained, confirming the important role of EPS during membrane fouling in MBR. In addition to adsorption, trace deposition of alginate also contributed to the initial slow TMP increase during the subcritical filtration. TMP increase during the long-term filtration was found not only due to the increase of the amount of deposition, but also the increase of specific cake resistance. A combined standard pore blocking and cake filtration model, using a critical pore size for the transition time determination, was developed and fit the experimental results well.

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Dragosavac, Marijana M. "Membrane emulsification and filtration for engineered particles." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8980.

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In many applications employing particles, the distribution of particle sizes has significant influence on the properties of the resultant material. Membrane emulsification (ME) is a method for manufacturing uniformly sized emulsion droplets where a dispersed phase is forced through a membrane into the continuous phase. It is the shear applied on the membrane surface that detaches the droplets thereby generating an emulsion. Formulation of the dispersed and the continuous phase influences the final droplet size of the emulsion. Therefore one of the aims of this research is to broaden the existing knowledge on particle production by membrane emulsification using nickel microengeneered disk membrane with cylindrical pores and the Dispersion Cell. The Dispersion Cell was successfully used to produce W/O/W emulsions (the oil phase was pumpkin seed oil). Also W/O emulsions (the water phase was acidified sodium silicate) were produced and additionally solidified in order to manufacture solid silica particles with high surface area and internal porosity. The particles were additionally functionalized using 3-aminopropyltrimethoxysilane and turned into ion exchange material capable to sorb copper. Since the silica particles do not swell such ion exchange material might be interesting for applications in nuclear industry. Having in mind an industrial application of membrane emulsification the Dispersion Cell cannot be used due to the problems with the scaling up. Therefore two novel systems: Oscillating and Pulsating were developed and reported for continuous production of the particles. Both systems were commissioned using sunflower oil for production of O/W emulsions. Additionally the Pulsating system was successfully used for production of complex coacervates. In the Oscillating system the nickel membrane was in the shape of a candle and the shear on the membrane surface was induced by vertical oscillations of the membrane. In the Pulsating system a tubular nickel membrane was used and the shear on the membrane surface was applied by oscillations of the continuous phase. The scaling up of both Oscillating and Pulsating system can be achieved by providing a larger membrane area (elongating the membrane) as well as connecting the membranes in parallel. It was successfully shown that a simple force balance can be used to model the size of emulsion droplets as a function of the shear stress. The average shear stress worked better when modelling the droplet sizes in the Dispersion Cell, but the correction for the droplet neck had to be taken into consideration when higher dispersed phase flow rates were used. In the Oscillating and Pulsating systems it was the maximal shear stress that gave the better prediction, but in both systems it was clear that additional forces were present which influenced the final droplet size. An alternative field of application for the Dispersion Cell, relevant to the tests of functionalized silica particles, was investigated. The Dispersion Cell was modified into a continuous flow stirred cell with a slotted nickel membrane on the bottom. The continuous flow stirred cell is shown to be an effective technique for both mass transfer kinetics as well as equilibrium data acquisition combining both into a single step, and simplifying ion exchange analysis. To commission the system the commercial ion exchange resin (Dowex 50W-X8) was used. Once determined, the design parameters can readily be used to model ion exchange contacting in a well mixed system, column operations or any process that requires ion exchange material. Using the continuous flow stirred cell it was shown that the silica particles produced using the Dispersion Cell and functionalized using 3-aminopropyltrimethoxysilane were capable to sorb copper. As a part of the collaboration within the DIAMOND (Decommissioning, Immobilisation And Management Of Nuclear wastes for Disposal) project a novel ion exchange material (copper hydroxide acetate suitable for iodide sorption) produced in the Department of Chemistry (Loughborough University) was successfully tested using the continuous flow stirred cell and equilibrium and mass transfer parameters were determined. The continuous flow stirred cell is particularly relevant to instances when the mass of ion exchange material available for the testing is low (less than 1g) and when dealing with hazardous or expensive materials. It is a technique employing microfiltration and ion exchange (or sorption), of the engineered particles that could be produced by membrane emulsification described in this thesis.

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Ofsthun, Norma Jean. "Cross-flow membrane filtration of cell suspensions." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14481.

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Siddiqui, Farrukh Arsalan. "Membrane filtration : fouling and cleaning in forward osmosis, reverse osmosis, and ultrafiltration membranes." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:bcaadfaa-62fb-4910-8218-bff387a19a11.

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A comparison of fouling in osmotically driven processes with that in pressure driven processes is the main focus of the thesis. Forward osmosis (FO) and reverse osmosis (RO) have received considerable attention for water treatment and seawater desalination. This research compared the nature of fouling in FO mode with that in RO starting with the same initial flux in connection with cleaning effects and then comparing to those in ultrafiltration membranes. In all cases, with cleaning as an integral part, the extent of fouling reversibility, and the question whether a critical flux could be determined were examined. The work during the first phase (undertaken at Oxford) quantified the removal of reversible fouling through rinsing by cold and hot water for a range of concentrations using the foulants dextran and carboxymethyl cellulose. The flux-TMP relationship was conventionally compared to that of the clean water flux. The later phase (at Singapore) compared the fouling in FO and RO by alginate in terms of multiple parameters using cellulose tri acetate (CTA) and thin film composite (TFC) membranes. Silica and alginate were selected as model foulants. Whilst experimental water flux profiles in the present study did not exhibit significant differences in trend between FO and RO fouling, foulant resistance for FO was found to be increasingly greater than for RO with the progression of the fouling tests. This was further corroborated by membrane autopsies post fouling tests; both foulant mass deposition density and specific foulant resistance for FO were greater than for RO. The analysis clearly revealed that FO is essentially more prone to fouling than RO which was presumably due to less flux decline in FO (or greater average flux) as compared to that in RO in result of ICP-self compensation effect which is opposite to the prevailing claim in the literature. Additionally, the present study did not find evidence that hydraulic pressure in RO has a role in foulant layer compaction. FO membrane fouling by real waters was the focus of the final phase of the research at SMTC. Pilot scale FO experiments were conducted on spiral wound CTA membrane with treated waste water obtained from a NEWater factory (Singapore) as the feed. In the second stage, experiments were repeated at bench scale with membrane coupons taken from the spiral wound membranes used earlier. The key finding was that the mass transfer coefficients in the Spiral-Wound module were around 50% lower than the corresponding values in the flat sheet unit and this severely limited the fluxes. The reason could be attributed to strong internal concentration polarisation in the former, where tightly wound spacers act to increase the structural parameter.

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Kyllönen, Hanna. "Electrically or ultrasonically enhanced membrane filtration of wastewater /." Espoo [Finland] : VTT Technical Research Centre of Finland, 2005. http://www.vtt.fi/inf/pdf/publications/2005/P576.pdf.

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Machenbach, Ingo. "Drinking Water Production by Coagulation and Membrane Filtration." Doctoral thesis, Norwegian University of Science and Technology, Department of Hydraulic and Environmental Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2142.

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Drinking water production with low-pressure hollow-fibre membranes is becoming increasingly more widespread as replacement for conventional separation technology. Upstream coagulation can mitigate fouling layer formation on membranes and allows removal of colloidal and soluble compounds smaller than the membrane pores. However, integrating membrane systems with coagulation bears the risk of impaired system performance due to unfavourable aggregate characteristics. This is of particular importance when treating humic substances due to their strong dependence on the solution environment.The experimental work in this study aimed at finding optimal coagulation, flocculation, and membrane operating conditions for treating a typically Nordic surface water with high humic content. Commercial aluminium-based coagulants and chitosan were applied in the pre-treatment step. Short, controlled flocculation was achieved by using a pipe, jet-mix, or packed-bed flocculator. An outside-in operated ultrafiltration system based on a polymeric hollow-fibre was used as separation unit.The study showed that optimized coagulation conditions are crucial to successful operation of the membrane unit. For the applied raw water (colour 50 mg Pt/L), a specific aluminium dosage of 3 mg Al/L and a coagulation pH in the range of 6–6.5 were found optimal with respect to permeate quality, membrane operation, and metal residuals. Coagulant dosages exceeding the optimal dosage and a pH drop increased hydraulically not-reversible fouling significantly. Chitosan neither met the expectations for NOM removal for the investigated raw water nor did its use seem favourable in combination with a polymeric membrane. Controlling floc aggregation can reduce pressure increase rates on the hollowfibre membrane provided that flocculators are designed for low velocity gradients (G<30 s−1). The packed-bed flocculator outperformed the other flocculators. However, flocculation times longer than 5 minutes should be applied to avoid rapid backwash pressure increases on the membrane.The membrane system was operated with fluxes in the range of 45–75 LMH during filtration and a 1.5 times higher value during backwashes. Forward filtration without air scouring proved feasible. To improve detachment of fouling layers, vigorous air scouring was used during backwashes. A filtration cycle of 30–60 minutes followed by a backwash interval of about 30 seconds gave good results. Increasing coagulant dosage and flux were the two most significant contributors to hydraulically non-reversible fouling. Water recovery only had a minor effect on the pressure development of the membrane. However, the results suggest that efficient sludge removal from the immersion tank is of importance. Operation at lower NOM concentrations left pressure increase rates unchanged, rendering the application potential of the system highest for NOM-rich surface waters.

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Taha, Taha. "CFD modelling of slug flow enhanced membrane filtration." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403424.

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Neale, Peta Anne. "Influence of solute-solute interactions on membrane filtration." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4106.

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An understanding of solute-solute interactions is essential for aquatic systems as this can affect the fate and behaviour of micropollutants in the environment and engineered systems. Despite the importance of solute-solute interactions there is a general lack of understanding which may be attributed to the fact that many engineering models overlook solute-solute interactions and that the quantification of such interactions is inherently difficult. When solute-solute interactions are considered, they are often studied at unrepresentative concentrations and do not consider the influence of organic matter type or solution chemistry. Steroidal hormones, such as estradiol and estrone, were selected as model micropollutants as they are ubiquitous in the aquatic environment due to constant introduction of wastewater effluent, and can have implications for growth and development of organisms including impaired fertility and behavioural abnormalities. The purpose of this study was to develop a methodology to quantify solute-solute interactions at environmental concentrations, and to determine the implications of such interactions in membrane filtration. A solid-phase microextraction (SPME) technique was developed to quantify solutesolute interactions at environmental (low) concentrations. Using SPME, organic matter-water partition coefficients (log KOM) were measured for a range of steroidal hormones including estradiol, estrone, progesterone and testosterone with different organic matter types such as humic acid. The dominant mechanism of hormoneorganic matter interactions was identified as hydrogen bonding. In the case of estrone and progesterone the log KOM values were significantly influenced by organic matter type and concentration, as well as solution chemistry. No difference was observed for estradiol and testosterone due to generally weaker sorption to organic matter. Previous studies have indicated that the presence of organic matter can alter micropollutant retention in membrane filtration. Much of the current literature focuses on solute-membrane interactions, as the influence of solute-solute interactions are typically difficult to determine in membrane filtration. Therefore, hormone-organic matter interactions were studied to determine if this interaction had an influence on hormone removal by ultrafiltration (UF) using a range of molecular weight cut-off (MWCO) membranes. The results indicated increased retention of estrone in the presence of humic acid, while organic matter concentration and solution chemistry influenced retention by affecting solute-solute interactions. The findings of this study indicate the importance of solute-solute interactions in membrane filtration and experimental log KOM results were used to quantify the findings and elucidate the influences of 1) membrane sorption, 2) solute-solute interactions and 3) solute-foulant interactions. Further, the removal of steroidal hormones using a magnetic ion exchange (MIEX®) resin with a range of MWCO UF membranes was studied as such sorbents can be used to improve micropollutant removal in wastewater treatment. Greater removal with IX-UF was observed compared to UF alone and the main hormone removal mechanisms were sorption to MIEX® and solute-fouling interactions. The findings of this study indicate that it is indeed possible to quantify solute-solute interactions at environmental concentrations using SPME, with hydrogen bonding being the main mechanism of interaction for steroidal hormones and organic matter. Further, micropollutant retention by membrane filtration can be influenced by solutesolute interactions.

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Moslehi, Ehsan. "Integrating membrane filtration forwater reuse in tissue mill." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231741.

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Water is an essential and indispensable component is the pulp- and paper production industry.The increase in energy costs, stricter environmental regulations and water resource shortageshave caused a reduction of the water footprint in the industry as well as an increase in waterrecycling and water circuit closure. Reducing water usage requires an understanding of wherecontaminants originate, as well as which streams are critical to the process and how they impactmill operation. The recirculation of water can cause contaminant accumulation; therefore millsemploy technologies for water treatment in the internal water cycles, the so-called ‘kidneys’.Application of membrane technology is one such option which can improve the recycled waterquality and reduce contaminant buildup.The present study was carried out on a lab-scale for the treatment of a tissue mill effluent usingmembrane separation. A combination of pretreatment methods and various membranes werecompared with regards to separation, flux and fouling. The AlfaLaval M20 device was to treatwastewater samples sent from the mill, where the permeate was recirculated to the feed tank.COD and TOC levels are compared with regards to determining the separation efficiency. Thepermeate flux was measured over the two-hour filtration period, as well as flux recovery todetermine fouling levels. Additionally, some economic aspects of the process are discussed.This study suggests the potential application of a combination of flocculation or centrifugationpretreatment, with reverse osmosis membranes for recycling water to replace freshwater intake.The results also indicate the possibility of using ultrafiltration as kidneys to decreasecontamination buildup for further water loop closure.

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Chateauneuf-Randon, Sixtine de. "Membranes d'hydrogel pour une filtration sélective." Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS255.

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Les hydrogels sont des matériaux polymères hydrophiles qui retiennent de grandes quantités d’eau tout en conservant une structure tridimensionnelle, ce qui les rend adaptés à des applications biomédicales et de filtration. Ce manuscrit se concentre sur les membranes d’hydrogels fabriquées à partir de polyéthylène glycol diacrylate (PEGDA) réticulé par UV en présence de chaînes de polyéthylène glycol (PEG) et d’un photoamorceur. Les membranes PEGDA/PEG sont sélectionnées pour leur robustesse mécanique et leur perméabilité élevée qui peut être ajustée en fonction de la concentration et de la masse molaire du PEG. Une caractéristique importante de ces membranes est que les chaînes de PEG restent piégées dans la matrice, permettant ainsi de les fonctionnaliser pour une filtration sélective. Notre étude montre que les membranes PEGDA/PEG peuvent retenir sélectivement de petites molécules formant des liaisons hydrogène. Nous fonctionnalisons également les membranes avec de l’acide polyacrylique (PAA) pour les rendre sélectives aux colorants chargés positivement. Les membranes PEGDA/PEG/PAA s’avèrent efficaces pour la rétention du bleu de méthylène et de la rhoda- mine B. La sélectivité de ces membranes est réversible par ajustement du pH, permettant ainsi de les rincer et de les réutiliser. L’analyse structurelle des membranes par diffusion de neutrons aux petits angles (SANS) révèle que les chaînes de PEG conservent une structure gaussienne dans la matrice de PEGDA, mais avec des rayons de giration et des longueurs de corrélation plus élevés qu’en solution, suggérant des contraintes topologiques comme des greffages chimiques ou des enchevêtrements. Une observation clé est que le rapport surface/volume de la matrice de PEGDA diminue avec l’ajout de PEG, indiquant la formation de cavités plus grandes, ce qui explique l’augmentation de la perméabilité observée. Lorsque la concentration en PEG dépasse une certaine valeur critique (C∗), le rapport surface/volume augmente, suggérant une diminution de la taille des cavités d’eau et, par conséquent, de la perméabilité. Nous développons également un modèle théorique pour prédire la perméabilité des hydrogels PEGDA/PEG en fonction de la masse molaire et de la concentration en PEG pour C < C∗, qui correspond bien aux mesures expérimentales Hydrogels are hydrophilic polymer materials that retain large amounts of water while maintaining a three- dimensional structure, making them suitable for biomedical and filtration applications. This manuscript focuses on hydrogel membranes made from polyethylene glycol diacrylate (PEGDA) crosslinked by UV in the presence of polyethylene glycol (PEG) chains and a photoinitiator. PEGDA/PEG membranes are selected for their me- chanical robustness and high permeability, which can be adjusted based on the concentration and molecular weight of PEG. An important feature of these membranes is that the PEG chains remain trapped in the ma- trix, allowing them to be functionalized for selective filtration. Our study shows that PEGDA/PEG membranes can selectively retain small molecules forming hydrogen bonds. We also functionalize the membranes with polyacrylic acid (PAA) to make them selective for positively charged dyes. PEGDA/PEG/PAA membranes prove effective in retaining methylene blue and rhodamine B. The selectivity of these membranes is reversible by adjusting the pH, allowing them to be rinsed and reused. Structural analysis of the membranes by small- angle neutron scattering (SANS) reveals that the PEG chains maintain a local gaussian structure within the PEGDA matrix, but with larger radii of gyration and correlation lengths than in solution, suggesting topolo- gical constraints such as chemical grafting or entanglements. A key observation is that the surface-to-volume ratio of the PEGDA matrix decreases with the addition of PEG, indicating the formation of larger cavities, which explains the observed increase in permeability. When the PEG concentration exceeds a certain critical value (C∗), the surface-to-volume ratio increases, suggesting a decrease in the size of the water cavities and consequently in permeability. We also develop a theoretical model to predict the permeability of PEGDA/PEG hydrogels as a function of the molecular weight and concentration of PEG for C < C∗, which corresponds well with experimental measurements

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Decock, Jérémy. "Approches micro/milli-fluidiques pour l'étude in situ de procédés de filtration frontale." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0788.

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Ce travail de thèse porte sur le développement technologique d’outils miniaturisés micro- (10 µm) et milli- (1 mm) fluidique, pour l’étude in situ de procédés de filtration frontale, en collaboration avec l’entreprise Solvay. Les outils développés permettent le suivi visuel de la formation de gâteaux de filtration en opérant des essais à pression ou à débit constant sur diverses suspensions colloïdales, jusqu’à des pressions trans-membranaires de l’ordre de 7 bars.L’étude millifluidique de la filtration de dispersions industrielles de silice colloïdale (Solvay, Silica), a permis de mettre en évidence la croissance de gâteaux compressibles et de corréler ces données aux signaux de pression, obtenus à débit imposé. Ces mêmes données sont confrontées aux lois classiques de la filtration (« cake filtration theory »), mettant en évidence que les modélisations classiques ne peuvent pas reproduire les comportements observés.La seconde partie de la thèse porte sur le développement d’un outil microfluidique, intégrant des membranes hydrogel nano-poreuses, pouvant résister à de fortes pressions (quelques bars). Ces membranes sont fabriquées in-situ par photo-polymérisation de formulations aqueuses contenant des PEG-diacrylates et des agents porogènes. Notre travail a permis une caractérisation précise de leur perméabilité en fonction de divers paramètres (formulation, temps d’exposition, géométrie). Ces mêmes membranes ont été utilisées pour suivre la filtration frontale de nanoparticules aux échelles microfluidiques, et ainsi estimer quantitativement la perméabilité des gâteaux formés This work deals with the technological development of miniaturized micro- (10 µm) and milli- (1 mm) fluidic tools for in-situ investigations of frontal filtration processes, in collaboration with Solvay. The tools that we developed, make it possible to monitor visually the formation of the filter cake, operating at constant-pressure or constant-flow rate filtration, on various colloidal suspensions, and up to trans-membrane pressures of 7 bars.We performed a millifluidic study of the filtration of industrial silica colloidal dispersions (Solvay, Silica), and we evidenced the growth of compressible cakes. We correlated these data to the pressure signals obtained at imposed flow rates. The comparison with theoretical predictions given by the classical laws of cake filtration theory, shows that such conventional models cannot reproduce the observed behaviors.The second part of this thesis reports the development of high pressure-resistive (several bars) microfluidic tools integrating nano-porous hydrogel-based membranes. These membranes are fabricated in situ by photo-polymerization of aqueous formulations containing PEG-diacrylates and porogen agents. We reported precise characterizations of their permeability in function of several parameters (formulation, exposure time, geometry). The same membranes were used to monitor frontal filtration of nanoparticles at the microfluidic scale, and thus to quantitatively estimate the permeability of the formed cakes

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Durif, Charlotte. "Elaboration de membranes non-oxydes de type SiBC pour la maîtrise de la contamination dans les réacteurs à eau pressurisée." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT179/document.

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Ce travail de thèse a porté sur le développement de membranes céramiques pour la filtration de colloïdes issus de la corrosion dans le circuit primaire des REP. La voie des polymères précéramiques a été mise en œuvre par la synthèse d’un polyborocarbosilane (PBC) à partir d’allylhydridopolycarbosilane conduisant à une céramique de type SiBC. Des billes de PMMA mono disperses d’une taille de 1,5 et 0,3 µm ont été préparées pour servir d’agent porogène pour créer une porosité contrôlée. Des objets micro-cellulaires 3D de forme circulaire ont été élaborés par pressage uni-axial avec ajout de billes de PMMA commercial pour servir de support macroporeux. Une étude de cristallinité à haute température (> 1000 °C) a été réalisée, montrant son influence sur la stabilité du matériau. La couche sélective a été préparée par dip-coating à partir de différentes formulations de barbotine contenant du PBC et les billes de PMMA élaborées. La stabilité physico-chimique des supports micro-cellulaires a été étudiée grâce à des essais de vieillissement en micro-autoclave en milieu primaire simulé. La résistance à la filtration a été testée grâce à un essai sur un dispositif de filtration connecté à un moyen d’essai de laboratoire permettant de simuler les conditions des REP This work has been focused on the development of ceramic membranes for the filtration of colloids resulting from corrosion in the primary loop of PWR. SiBC ceramics were synthesized by the preceramic polymers route from a polyborocarbosilane (PBC) obtained from allylhydridopolycarbosilane. Single-dispersed PMMA beads with a size of 1.5 and 0.3 μm were prepared to be used as a porogen agent to lead to a controlled porosity of the selective layer. 3D micro-cellular objects with a circular shape were developed by uni-axial pressing with the addition of commercial PMMA beads to serve as a macroporous support. A crystallinity study at high temperature (> 1000 ° C) was carried out showing its influence on the stability of the material. The selective layer was prepared by dip-coating from various slurry formulations containing PBC and the prepared PMMA beads. The chemical and physical stability of the microcellular supports was studied by ageing tests in a simulated primary water chemistry. The filtration resistance was tested by means of tests on a filtration device connected to a laboratory loop which simulates the conditions of the PWRs

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Wu, Nan. "Filtration de nanoparticules par procédés membranaires." Ecole centrale de Marseille, 2013. http://www.theses.fr/2013ECDM0017.

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Tomietto, Pacôme. "Contribution des polyhydroxyalcanoates (PHA) dans l'élaboration de matériaux membranaires pour des séparations en phase liquide." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S034.

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Les procédés membranaires sont aujourd'hui largement utilisés dans différents secteurs d'application, comme le traitement de l'eau ou les industries pharmaceutique et agroalimentaire. En comparaison aux autres technologies de séparation, la filtration membranaire a l'avantage d'être économe en énergie, de ne pas nécessiter l'utilisation de produits chimiques supplémentaires et d'être facilement mise à l'échelle du procédé. Cependant, les procédés d'inversion de phase, couramment utilisés pour la fabrication de membranes polymères, sont souvent nocifs pour l'environnement. En effet, ils utilisent majoritairement des polymères issus de ressources fossiles, aussi connus pour être la cause de pollutions environnementales, et requièrent des quantités importantes de solvants toxiques. Cette thèse vise à contribuer au développement de membranes plus respectueuses de l'environnement. Ici, le poly(3-hydroxybutyrate-co-3-hydroxyvalerate) a été utilisé comme matériau membranaire biosourcé et biodégradable. Les membranes ont été fabriquées au moyen de différentes techniques, l'inversion induite par évaporation du solvant et l'inversion de phase inuite par addition d'un non-solvant. Les membranes en biopolymère ont été fabriquées avec succès en utilisant un solvant vert (le Cyrène™). Grâce à l'étude de l'influence de la composition du collodion ainsi que de celle des paramètres de mise en oeuvre, la microstructure membranaire a pu être contrôlée. Les membranes montrent des performances prometteuses pour des applications en microfiltration et pervaporation The use of membrane filtration is now widely implemented in the separation processes and is used in a large range of application sectors, such as the water treatment, the pharmaceutical or the food industries. Among the separation technologies, membrane filtration has the advantages to be energy-efficient, to not require any additional chemicals and to be easily scalable. However, the commonly phase inversion processes used to fabricate polymeric membranes can be considered as harsh for the environment. Thus, they require the use of fossil-based polymers, known to cause the depletion of non-renewable resources and environmental pollutions, and also request large amount of toxic solvents. The objective of this study is to fabricate more sustainable membranes. Herein, the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) has been used as biobased and biodegradable membrane material. Different phase inversion techniques have been studied. The membranes have been prepared either by evaporation induced phase separation or by non-solvent induced phase separation. The biopolymer-based membranes were successfully produced using a green solvent (the Cyrene™). By studying the effects of the dope solution composition and fabrication parameters, the membrane microstructure has been tailored. The membranes show interesting performances related to microfiltration and pervaporation applications

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18

So, Wing Kin. "Development of low-cost membrane module for direct sewage filtration /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20SO.

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19

Unlu, Meltem. "Indigo Dyeing Wastewater Treatment By The Membrane Based Filtration Process." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609464/index.pdf.

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In the present study, the recovery of the indigo dyeing rinsing wastewater originating from a denim textile mill to the degree of reuse quality, which generally requires nanofiltration (NF), was investigated. In order to control flux decline and hence to maintain an efficient NF coagulation, microfiltration (MF) and sequential MF plus ultrafiltration (UF) pretreatment process alternatives were tested. All pretreatment alternatives were optimized to reduce chemical oxygen demand (COD) and color load to NF. Coagulation process was investigated using the coagulants, aluminum sulfate (Al2(SO4)3.18H2O) and ferric chloride (FeCl3.6H2O) by running a series of jar tests. The results showed that coagulation process did not provide an effective and efficient pretreatment due to high dose of coagulant requirement. MF tests run by using 0.45, 2.5 and, 8 &micro m membranes indicated that MF through 0.45 &micro m pore-sized membrane is the best process providing 64% color and 29% COD removals, leading to a color value of 2493 Pt-Co and COD of 892 mg /L in the permeate. Application of sequential MF+UF filtration provided a significant benefit over single MF in terms of rejections and also permeate flux. UF applied after MF provided additional 62% color and 4% COD removals leading to 960 Pt-Co color and 856 mg/L COD. NF tests conducted using pretreated wastewater via single MF and sequential MF+UF indicated that single MF is the best pretreatment to NF and this treatment scheme provided 99% color, 97% COD and 80 % conductivity removals and satisfied reuse criteria.

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20

Moore, Kenneth. "Treatment of Arsenic Contaminated Groundwater using Oxidation and Membrane Filtration." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/866.

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Arsenic is a known carcinogen, causing cancers of the skin, lungs, bladder and kidney. Current research suggests that drinking water is the most common pathway for long-term low dose exposure. Arsenic contaminated drinking water has caused serious health problems in many countries including: India, Bangladesh, Argentina, Chile, Taiwan, the United States and Canada. Nanofiltration (NF) is a promising technology for arsenic removal since it requires less energy than traditional reverse osmosis membranes. Several studies have shown that nanofiltration is capable of removing the oxidized form of arsenic [As(V)] while the reduced form of arsenic [As(III)] is poorly removed. To exploit this difference it has been suggested that a pretreatment step which oxidizes the As(III) to As(V) would improve the performance of membrane filtration, but this has never been demonstrated. The research had three objectives: The first was to investigate the ability of NF membranes to treat arsenic contaminated groundwater and evaluate the influence of the membrane type and operating conditions. Secondly, the effectiveness of a solid phase oxidizing media (MnO2) to oxidize arsenite to arsenate was investigated. Lastly, the MnO2 was combined with NF membrane filtration to determine the benefit, if any, of oxidizing the arsenic prior to membrane filtration. A pilot membrane system was installed to treat a naturally contaminated groundwater in Virden, Manitoba, Canada. The groundwater in Virden contains between 38 and 44 µg/L of arsenic, primarily made up of As(III), with little particulate arsenic. In the first experiment three Filmtec® membranes were investigated: NF270, NF90 and XLE. Under all conditions tested the NF90 and NF270 membranes provided insufficient treatment of Virden's groundwater to meet Canada's recommended Interim Maximum Acceptable Concentration (IMAC) of 25 µg/L. The XLE membrane provided better arsenic removal and under the conditions of 25 Lmh flux and 70% recovery produced treated water with a total arsenic concentration of 21 µg/L. The XLE membrane is therefore able to sufficiently treat Virden's ground water. However treatment with the XLE membrane alone is insufficient to meet the USEPA's regulation of 10 µg/L or Canada's proposed Maximum Allowable Concentration (MAC) of 5 µg/L. The effects of recovery and flux on total arsenic passage are consistent with accepted membrane theory. Increasing the flux increases the flow of pure water through the membrane; decreasing the overall passage of arsenic. Increasing the recovery increases the bulk concentration of arsenic, which leads to higher arsenic passage. The second experiment investigated the arsenic oxidation capabilities of manganese dioxide (MnO2) and the rate at which the oxidation occurs. The feed water contained primarily As(III), however, when filtered by MnO2 at an Empty Bed Contact Time (EBCT) of only 1 minute, the dominant form of arsenic was the oxidized form [As(V)]. At an EBCT of 2 minutes the oxidation was nearly complete with the majority of the arsenic in the As(V) form. Little arsenic was removed by the MnO2 filter. The third and final experiment investigated the benefit, if any, to combining the membrane filtration and MnO2 treatment investigated in the first and second experiments. The effect of MnO2 pretreatment was dramatic. In Experiment I, the NF270 and NF90 membranes were unable to remove any arsenic while the XLE removed, at best, approximately 50% of the arsenic. Once pretreated with MnO2 the passage of arsenic through all of the membranes dropped to less than 4 µg/L, corresponding to approximately 91% to 98% removal. The dramatic improvement in arsenic removal can be attributed to charge. All three membranes are negatively charged. Through a charge exclusion effect the rejection of negatively charged ions is enhanced. During the first experiment, As(III) (which is neutrally charged) was the dominant form of arsenic, and was uninfluenced by the negative charge of the membrane. Once oxidized to As(V), the arsenic had a charge of -2, and was electrostatically repelled by the membrane. This greatly improved the arsenic rejection characteristics of the membrane. Nanofiltration alone is not a suitable technology to remove arsenic contaminated waters where As(III) is the dominant species. When combined with MnO2 pre-oxidation, the arsenic rejection performance of nanofiltration is dramatically improved.

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Kovalsky, Peter Chemical Sciences &amp Engineering Faculty of Engineering UNSW. "Characterisation of fouling behaviour on membrane filtration of aggregated suspensions." Publisher:University of New South Wales. Chemical Sciences & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41531.

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It is widely accepted that flocculation improves filtration performance by increasing cake permeability. This principle is important in submerged membrane filtration for drinking water applications where the feed material can potentially contain fouling components which prohibit the extended operation of the filter. Less well understood is the impact of floc properties on the hydraulic properties of the fouling layer formed on the membrane or the impact of hydrodynamic conditions during treatment on the floc-fouling layer relationship. In order to advance knowledge of this area, a set of tools were developed to characterise the cake formed during constant pressure filtration in terms of the compressive yield stress and permeability as a function of solid volume fraction. Using an iterative procedure, the optimal parameters for these models are calculated as are pressure and solid fraction distribution profiles. Input parameters to the numerical analysis are flux and final cake height data obtained from batch filtration experiments which are driven to steady state. The calculated material properties are compared against piston and centrifuge data with good agreement. Application of the material properties to constant flux filtration involved development of a numerical model for simultaneous consolidation and cake formation. Flocculated yeast was used as the test system with the predicted transmembrane pressure rise as a function of time under constant flux conditions compared with experimental data. Good agreement is observed between model and experimental trends. The close correspondence between experimental and predicted results also suggests that it may be possible to predict trans-membrane pressure rise during constant flux filtration on the basis of material properties determined through simple constant pressure steady state experiments. A good account of the data was also achieved through extension of the general equation to include an empirical model for the consolidation time constant. These new tools were applied to characterise the cakes formed under well controlled shear conditions. To avoid complications with modeling the sheared filtration system, the filtration was performed below the critical shear rate for particle rejection. This was verified by in-situ particle counts and size measurement. The material properties were determined for flocculated yeast filtered in a coni-cylindrical Couette at several shear rates below the critical shear. Comparison of the compressive yield stress showed that cakes subjected to shear required less compressive stress to collapse. It is shown that the general equation for constant flux could be modified to encompass this effect through inclusion of an empirical shear parameter. The transmembrane pressure rise is able to be described well by this model. DEM particle simulation was performed to investigate the effect of floc size and structure on cake permeability. Flocs of known size and structure were placed in a virtual suspension and the process of consolidation simulated by application of a compressive force. The permeability of the cake was calculated by computational fluid dynamics at various stages of the consolidation showing that the larger compact floc showed the highest permeability despite the highly compact structures formed. Comparison of pore size distribution also confirmed that several larger pores remained after consolidation of the larger compact flocs. Further work needs to be undertaken to pin point the microstructural mechanism governing this behaviour and whether the presence of fluid passing through these pores under normal filtration flows affects the retention of permeability of cakes under compression. Furthermore, the shear environment required to minimise the detrimental effects caused by shear enhanced cake collapse and also to form flocs of compact structure and large size needs to investigated.

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Busca, Gerald Thierry Michel. "Treatment of semi-synthetic metalworking fluids : membrane filtration and bioremediation." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/10239/.

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Waste engineering fluids, such as coolants and cutting fluids, are difficult to treat because they have variable physical natures, are particularly toxic and have a very high Chemical Oxygen Demand. The complex and unknown chemical content of the many different products available is also problematic. Current technologies, such as nanofiltration or chemical treatment, are quite effective at reducing the COD of the waste metalworking fluids before disposal. These technologies remove free or emulsified oil and high molecular weight components, but they have their limitations. In addition, the more stringent legislation on waste disposal and effluent discharge induces an economical stress on engineering industries. It can be anticipated that future legislations will introduce eco-toxicology measurements into industrial effluent discharge consents. A modular on-site treatment plant to treat semi-synthetic metalworking fluids was developed in this thesis. The approach was to combine different technologies and to inter-optimise their performances. The technologies used were membrane filtration, bioremediation and chemical treatment. The use of activated carbon was also studied. Membrane filtration included the study of ultrafiltration and nanofiltration. For the bioremediation process, a bio-consortia was developed and tested over 8 months. A final design of the whole process is given. The proposed treatment plant transforms the waste metalworking fluid into two products: very low chemical oxygen demand aqueous phase at 30 mg/l COD and a recovered oil showing a calorific value of 42 kJ/kg which could be a possible commodity. The whole treatment plant is scalled-up for thye treatment of 500 L of waste metalworking fluid per day.

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23

Paolini, Fabrizio Dario Re de. "Development of a membrane filtration process for oil/water separation." Thesis, University of Surrey, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301099.

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24

Nagappan, Subbiah Nagappan. "Waste stream reclamation for food manufacturing operations using membrane filtration." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1530804776915171.

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25

Habibi, Sepideh. "Caractérisation multi-échelles d'un système de filtration en présence d'un biofilm." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0042/document.

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Dans un procédé de filtration, un fluide traverse une membrane (barrière sélective). Une force motrice s’applique entre les deux côtés de la membrane qui peut être un gradient de pression, température ou un potentiel électrique/chimique. Dans les procédés de filtration par un gradient de pression, certains composés du milieu fluide, traversent la membrane alors que d’autres sont retenues sur la surface membranaire. Ces procédés sont très utiles dans différents domaines de l’industrie, notamment en ce qui concerne le traitement des eaux et des effluents, biotechnologie, agroalimentaire et pharmacie. En plus les procédés de filtration offrent des installations plus compactes avec une optimisation des coûts opérationnels comparant avec des procédés traditionnels de séparation notamment distillation et cristallisation. Par ailleurs, ces procédés se réalisent en absence des additifs chimique et changement de la phase. Dans cette étude, on se focalise sur les procédés de microfiltration. L’inconvénient principal de ces procédés est l’accumulation continue de particules/molécules sur la surface de la membrane. Ceci affecte la sélectivité de la membrane, modifie la qualité et la quantité de liquide passant à travers la membrane et conduit à une augmentation des coûts et de l’énergie. Le Colmatage (encrassement) membranaire se produit dans tous les types de procédés membranaires et par conséquent est connu le principal obstacle à l’utilisation répandue de ces procédés. Différentes techniques sont utiles pour surmonter les effets de l’encrassement de la performance de la membrane: le traitement physico-chimique des membranes utilisées, la modification des conditions opératoires (flux tangentiel de la solution d’alimentation sur la surface de la membrane est souvent appliqué pour réduire au minimum l’accumulation de particules), l’utilisation de membranes moins sensibles au colmatage, etc. Tout dépendant de la nature des solutions traitées, les particules déposées sont très variables. Les micro-organismes, des matières organiques naturelles notamment les protéines, les polysaccharides, les substances humides, les oxydes inorganiques et les sels contribuent au colmatage des membranes. Dans les dernières années, un grand nombre d’études expérimentales ont été investis pour comprendre les mécanismes de colmatage. Il a été souligné que les propriétés physico-chimiques de la membrane, la chimie des solutions et les conditions opératoires sont les trois principaux facteurs influant sur les mécanismes de colmatage. En parallèle, les modèles théoriques ont été proposés pour confirmer / décrire les observations expérimentales. La modélisation du colmatage membranaire est un outil essentiel pour évaluer les mécanismes qui le causent. Il permet également prédire la performance du système de filtration et par conséquent trouver des stratégies adaptées pour empêcher la modification de la performance membranaire pendant le procédé de filtration. En général, les modèles de classifient en deux grandes catégories: les modèles de transport de masse qui se concentrent sur le transport de solutés dans le procédé de filtration, et les modèles de colmatage basés sur le blocage des particules/molécules sur la surface ou à l’intérieur de la membrane. Dans la plupart des cas, les modèles dépendent fortement des paramètres empiriques ou semi-empiriques et restent phénoménologique. 1. Avoir une meilleure compréhension des mécanismes du colmatage membranaire lors de la filtration d’un milieu liquide contenant les micro-organismes en suspension. Il est important de souligner que des eaux industrielles et des eaux usées dans plusieurs domaines appartiennent à ce type d’effluents. 2. Proposer un modèle macroscopique décrivant les mécanismes de colmatage observés. [...] During a membrane filtration process, a liquid medium is filtered through a membrane(selective barrier). The applied driving force between two sides of the membrane can be a gradient of pressure, temperature or a chemical/electrical potential.In pressure driven filtration processes (application of a pressure gradient as driving force between two sides of the membrane), certain components of the liquid medium pass through the membrane, while others are retained at the membrane surface. These processes are widely used as separation techniques in different industrial fields like waste water treatment, biotechnology, food and pharmacy. Compared to conventional techniquesof separation (distillation, crystallization, ...), membrane processes offer more compact installations with more optimized operational costs. Moreover, membrane processes are mainly performed in absence of chemical additives and phase change. In this work we focus on the pressure-driven microfiltration membrane processes.The main disadvantage of these processes is the continuous accumulation of particles on the membrane surface. This affects the membrane selectivity, modifies the quality and the quantity of the liquid passing through the membrane and leads to an increase of energy costs. Membrane fouling occurs in all types of membrane processes and therefore is known as the major obstacle for widespread use of these processes. Different techniques are used to overcome the effects of fouling on the membrane performance : physical-chemical treatment of used membranes, modification of the operational conditions (tangential flow of the feed solution to the membrane is often applied for minimizing the particle accumulation to the membrane surface), use of membranes less susceptible to fouling, etc. Depending on the nature of the treated solutions, the deposited particles are highly variable. Microorganisms, natural organic matter such as proteins, polysaccharides, humid substances, inorganic oxides and salts contribute notably to membrane fouling.It should be noted that membrane fouling problem is a multi-physics (hydrodynamics,mass transport, physics, chemistry), multi-scale (different length scales are involved:molecules, pores and membrane surface) and time dependent (evolution of the membrane microstructure and the molecule-surface interactions) phenomena.In the last decades, a huge number of experimental studies have been invested to understand fouling mechanisms. It has been pointed out that membrane physicochemical properties, solution chemistry and operational conditions are the three major factors affecting the fouling mechanisms. In parallel, theoretical models have been proposed to confirm/describe the experimental observations.Modeling of membrane fouling is an essential tool for assessing the fouling mechanisms. It helps predicting the membrane performance and consequently finding adapted strategies to prevent their modification during the filtration process.In general, the models can be classified into two main categories: mass transport models which focus on solute permeation during the filtration process, and fouling models based on particle or solute blocking within the membrane porous structure. In most of the cases, models depend strongly on the empirical or semi-empirical parameters and thus remain phenomenological. Two main objectives have been set for the present work: 1. Get a better understanding of the membrane fouling mechanisms during filtration of a liquid medium containing suspended microorganisms. It should be pointed out that several Industrial streams and wastewaters belong to this kind of effluents.2. Propose a macroscopic model describing the observed fouling mechanisms. [...]

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Fonseca, Anabela Duarte. "Denitrification in Membrane Bioreactors." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35212.

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Three membrane bioreactors, a low flux filter (LFF), a diafilter (DF), and an ion-exchange (IE) membrane bioreactor were used to treat water polluted with 50 ppm-N nitrate. The three systems were compared in terms of removal efficiency of nitrate, operational complexity, and overall quality of the treated water. In the low flux filter (LFF) membrane bioreactor an hemo-dialysis hollow fiber module was used and operated continuously for 29 days with a constant flux of permeate. The performance of the system was constant during the span of the experiment, which demonstrated that when the module was operated under constant low flux of permeate, the membrane filtration process was not affected by fouling. The removal rate of the LFF was 100% since the treated effluent did not contain nitrate or nitrite. The volumetric denitrification rate was 240 g-N day-1 m-3, which is within the range of denitrification rates obtained in tubular membrane modules. The treated effluent contained acetate, the carbon source of the biological process, and other inorganic nutrients, which showed that operating this ultrafiltration module at controlled flux did not improve the retention of these substances in the bioreactor. The same hemo-dialysis hollow fiber module employed in the LFF system was used in the diafilter (DF) membrane bioreactor. In the DF system, however, the membrane module was used as a contactor that separated the treated water and the bioreactor system, which allowed the transfer of solutes through the membrane porous structure and supported the growth of a biofilm on the membrane surface. The nitrate removal rate of the DF system increased from 76% to 91% during the 17 days assay. Unfortunately, this improvement could be attributed to microbial contamination of the water circuit because significant concentrations of the carbon source, acetate, nutrients, and nitrate were found in the treated effluent. The volumetric denitrification rate of the system was 200 g-N day-1 m-3, and the surface denitrification rate was lower than values previously reported for contactor membrane bioreactors. The results hereby presented do not evidence any advantage of operating the Filtral 20 ® membrane module as a contactor instead of as a filter such as in the LFF system. On the other hand, the third system herein presented, the IE membrane bioreactor, demonstrated several advantages of a contactor configuration but with a non-porous ion exchange membrane module in place of the Filtral 20 ®. As in a contactor system, the anion membrane provided a surface for biofilm growth, facilitated the transport of nitrate, and prevented mixing of treated water and bioreactor medium. Compared to the two previous systems, the most remarkable result of the IE was the reduction of secondary pollution in the treated water. The concentrations of phosphate and ethanol were zero and less than 1% of the concentration in the bioreactor, respectively. In addition, the IE system was less complex than the two other systems because the ion exchange membrane is non-porous. Therefore, unlike with porous contactors, it was not necessary to control the flux of treated water that could be lost through the bioreactor. The average surface denitrification rate of the IE system was 7.0 g-N day-1 m-2, which is higher than what had been reported for other contactor denitrification systems. However, because of the low surface to volume ratio of the membrane module that was used, the volumetric denitrification rate of the IE system was low, equivalent to 65 g-N day-1 m-3. Master of Science

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Rane, Mahendra. "Porous Membrane." Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201000336.

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Membrane processes can cover a wide range of separation problems [with a specific membrane (membrane structure) required for every problem]. Thus, there are membranes available that differ in their structure and consequently in the functionality. Therefore membrane characterization is necessary to ascertain, which membrane may be used for a certain separation. Membranes of pore size ranging from 100nm to 1μm with a uniform pore size are very important in membrane technology. An optimum performance is achieved when the membrane is as thin as possible having a uniform pore size. Here in this thesis, membranes were synthesized by particle assisted wetting using mono-layers of silica colloids as templates for pores along with polymerizable organic liquids on water surface. The pore size reflects the original shape of the particles. Thus it is possible to tune the pore size by varying the particle size. This method is effective to control pore sizes of membranes by choosing silica particles of suitable size. This approach gives a porous structure that is very thin, but unfortunately limited in mechanical stability. Thus there is a need for support which is robust and can withstand the various mechanical stresses. A small change in the membrane or defect in the layered structure during the membrane formation can have drastic effect on the assembly. Lateral homogeneity of the layer generated by the particle assisted wetting can be judged by examination of its reflectivity, but once it is transferred on any solid support this option is no more. So a method is needed to detect the cracks or the inhomogenity of the membrane which can be detected even after the transfer. To tackle this problem a very simple and novel technique for characterizing the membrane by fluorescence labeling and optical inspection was developed in this thesis. The idea was to add a fluorescent dye which is poorly water soluble to the spreading solution comprising of the particles and the monomer. If the dye survived the photo-cross linking, then it would be embedded in the cross-linked polymer and would serve as a marker. Defects and inhomogenity would show up as cracks and spots. By the method that we have developed, we can detect our membrane from the support and spot defects.

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Regula, Camille. "Etude du vieillissement des membranes dans le domaine de l’agroalimentaire : production d’eau potable et filtration du lait." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4313.

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Quel que soit le domaine d'application, les membranes doivent fréquemment subir des procédures de nettoyage et/ou de désinfection afin d'éliminer le colmatage qui découle de la filtration. Ces nettoyages sont responsables d'une accélération du vieillissement des matériaux qui impacte directement les performances techniques et économiques des procédés membranaires. La pérennité de ces derniers passe par l'identification des principaux facteurs responsables du vieillissement et par la compréhension des mécanismes qui le régissent. Le vieillissement statique de membranes d'ultrafiltration spiralée en polyethersulfone et fibres creuses en polysulfone respectivement utilisées pour la filtration du lait et pour la production d'eau potable a été étudié. Ce vieillissement a été mis en place selon la méthodologie des plans d'expériences qui a permis l'étude simultanée de la concentration, de la température et du temps de contact membrane/détergents et ce, pour différents détergents formulés couramment utilisés sur les sites de production (alcalin, acide, enzymatiques, oxydant chloré et oxydant non chloré). Les résultats ont permis de modéliser statistiquement les modifications membranaires induites par chaque détergent. Ces modifications ont été suivies aussi bien à l'échelle microscopique que macroscopique afin d'appréhender le phénomène de vieillissement dans sa globalité : propriétés de transport, propriétés mécaniques, propriétés de surface, ainsi que les modifications de la composition chimique du polymère constitutif de la membrane. Des préconisations d'utilisation des différents produits sont proposées : véritable carnet de bord les industriels In Food Industries, using membrane processes, contact with cleaning chemicals is believed to play an important role in membrane ageing. In this thesis, polysulfone hollow fibers and polyethersulfone spiral wound membranes were used to simulate the industrial cleaning in static conditions. Ageing of the membrane was mimicked by immersing samples in solutions containing commercial detergents with various concentrations, temperatures and soaking times defined by experimental designs. In an innovative way in the chemical membranes ageing research, an approach based on methodological tools has been realized for different formulated detergents (alkaline, acidic, enzymatic, oxidant and biocide). The main interest is to achieve a relevant ageing pattern without using an accelerated ageing protocol which has been proved to be not relevant. Results allow modeling macroscopic ageing involved by each detergent. Those modifications have been studied as well at the macroscopic scale as at the microscopic scale in order to put membrane ageing in a global perspective: flux, mechanical properties, surface properties, polymer modifications. Specifications of using can be advised according to membranes and products which represent a real oversight handbook about membrane cleaning for industrial users

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Abdullah, Syed Zaki. "Investigation of effect of dynamic operational conditions on membrane fouling in a membrane enhanced biological phosphorus removal process." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/264.

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The membrane bioreactor (MBR) is becoming increasingly popular for wastewater treatment, mainly due to its capability of producing high quality effluent with a relatively small footprint. However, high plant maintenance and operating costs due to membrane fouling limit the wide spread application of MBRs. Membrane fouling generally depends on the interactions between the membrane and, the activated sludge mixed liquor, which in turn, are affected by the chosen operating conditions. The present research study aimed to explore the process performance and membrane fouling in the membrane enhanced biological phosphorus removal (MEBPR) process under different operating conditions by, (1) comparing two MEBPRs operated in parallel, one with constant inflow and another with a variable inflow, and by, (2) operating the MEBPRs with different solids retention times (SRT). On-line filtration experiments were conducted simultaneously in both MEBPR systems by using test membrane modules. From the transmembrane pressure (TMP) data of the test membrane modules, it was revealed that fouling propensities of the MEBPR mixed liquors were similar in both parallel reactors under the operating conditions applied, although the fouling propensity of the aerobic mixed liquors of both reactors increased when the SRT of the reactors was reduced. Routinely monitored reactor performance data suggest that an MEBPR process with a varying inflow (dynamic operating condition) performs similarly to an MEBPR process with steady operating conditions at SRTs of 10 days and 20 days. Mixed liquor characterization tests were conducted, including critical flux, capillary suction time (CST), time to filter (TTF) and, bound and soluble extracellular polymeric substances (EPS) were quantified, to evaluate their role on membrane fouling. The tests results suggest that the inflow variation in an MEBPR process did not make a significant difference in any of the measured parameters. With decreased SRT, an increase in the concentrations of EPS was observed, especially the bound protein, and the bound and soluble humic-like substances. This suggests that these components of activated sludge mixed liquors may be related to membrane fouling. No clear relationship was observed between membrane fouling and other measured parameters, including critical flux, normalized CST and normalized TTF. Applied Science, Faculty of Civil Engineering, Department of Graduate

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Abdullah, Syed. "Investigation of effect of dynamic operational conditions on membrane fouling in a membrane enhanced biological phosphorus removal process." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/264.

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The membrane bioreactor (MBR) is becoming increasingly popular for wastewater treatment, mainly due to its capability of producing high quality effluent with a relatively small footprint. However, high plant maintenance and operating costs due to membrane fouling limit the wide spread application of MBRs. Membrane fouling generally depends on the interactions between the membrane and, the activated sludge mixed liquor, which in turn, are affected by the chosen operating conditions. The present research study aimed to explore the process performance and membrane fouling in the membrane enhanced biological phosphorus removal (MEBPR) process under different operating conditions by, (1) comparing two MEBPRs operated in parallel, one with constant inflow and another with a variable inflow, and by, (2) operating the MEBPRs with different solids retention times (SRT). On-line filtration experiments were conducted simultaneously in both MEBPR systems by using test membrane modules. From the transmembrane pressure (TMP) data of the test membrane modules, it was revealed that fouling propensities of the MEBPR mixed liquors were similar in both parallel reactors under the operating conditions applied, although the fouling propensity of the aerobic mixed liquors of both reactors increased when the SRT of the reactors was reduced. Routinely monitored reactor performance data suggest that an MEBPR process with a varying inflow (dynamic operating condition) performs similarly to an MEBPR process with steady operating conditions at SRTs of 10 days and 20 days. Mixed liquor characterization tests were conducted, including critical flux, capillary suction time (CST), time to filter (TTF) and, bound and soluble extracellular polymeric substances (EPS) were quantified, to evaluate their role on membrane fouling. The tests results suggest that the inflow variation in an MEBPR process did not make a significant difference in any of the measured parameters. With decreased SRT, an increase in the concentrations of EPS was observed, especially the bound protein, and the bound and soluble humic-like substances. This suggests that these components of activated sludge mixed liquors may be related to membrane fouling. No clear relationship was observed between membrane fouling and other measured parameters, including critical flux, normalized CST and normalized TTF.

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31

Postlethwaite, Johnathan. "Vibrating membrane filtration : microfiltration performance during the processing of biological feedstreems." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407601.

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32

Sanches, Sandra. "Integration of Membrane Filtration and Photolysis Processes for Drinking Water Treatment." Doctoral thesis, Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica, 2013. http://hdl.handle.net/10362/12031.

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Dissertation presented to obtain the Ph.D degree in Engineering and Technology Sciences, Chemical Engineering. Water is a fundamental resource for life. The presence of hazardous micropollutants such as pesticides and hormones in drinking water sources as well as the evidence of their presence in several treated waters raised concerns regarding the quality of the water intended for human consumption. The development of new technologies which are able to cope with these micropollutants and ensure the fulfillment of future more stringent regulations is therefore needed. Low pressure ultraviolet direct and indirect photolysis (using hydrogen peroxide and titanium dioxide) and nanofiltration are extremely promising technologies to effectively remove organic micropollutants from water.(...)

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33

Voittonen, Sandra. "Minimization of Fouling for Treatment of Municipal Wastewater with Membrane Filtration." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235946.

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In this thesis project, treatment of municipal wastewater using ultrafiltration is evaluated to investigate ways to prevent or minimize fouling from occurring. The aim of this project is to examine which factors play a significant role in causing different types of fouling, in order to minimize the resulting effect and thereby increase the efficiency and lifetime of the membrane. The project started with a broad literature study, which researched which methods are currently used to treat wastewater on an industrial level and other state-of-the-art solutions that are available. This was then used to form an experimental plan where two membranes were tested using a pilot plant constructed at IVL’s research facility Hammarby Sjöstadsverk. Firstly, a polymeric membrane was tested using different pressures to see the influence on the membrane flux. The results indicated that although a higher pressure lead to higher flux, there is an upper limit for the flux that was achieved at 5 bar, since similar flux values were found at 5 bar, 7 bar and 9 bar. Also, though a higher flux did lead to a more rapid decrease in flux initially, all curves plateaued after approximately 40 minutes. An average recovery of the membrane flux capacity was 88.7%, where the highest one was achieved with a pressure of 7 bar. Secondly, a ceramic membrane was tested using a factorial design with three parameters, each having a low and high setting. The parameters that were tested were the total operating time, the pressure and the cleaning time of the membrane, with the aim to investigate how each parameter influenced the fouling and the removal of organic compounds from the wastewater. The fouling was analyzed by measuring the flux across the membrane and showed mixed results. Fouling could be removed and the flux often had a recovery of 100% or more, however, no clear conclusion could be drawn to which parameter was the most influential for this high removal percentage. As for the removal of organic compounds, an average removal of 66.9% was achieved and it was determined that the cleaning time was the most influential parameter, and the interaction between running time and pressure being the second most influential.

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34

Walker, Steven. "Hollow Fiber Ultrafiltration of Ottawa River Water: Impact of Different Pre-treatment Schemes." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31323.

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To minimize membrane fouling many water treatment plants pre-treat water prior to microfiltration (MF) or ultrafiltration (UF). Coagulation/flocculation/sedimentation is a common form of pre-treatment, but little research has been conducted on floatation as a part of the pre-treatment. The objective of this thesis is to compare pre-treatment with floatation and with sedimentation for Ottawa River water, a typical Northern Canadian water with a high natural organic matter (NOM) content and a large hydrophobic (HPO) NOM fraction. Fouling tests consisted of multiple filtration/backwashing cycles performed by an automated bench-scale UF hollow fiber membrane system. Test were conducted with Ottawa River water (ORW) and ORW subjected to three different types of pre-treatment conducted at closely-located full-scale water treatment plants, including one using floatation. Both Alum pre-treatments resulted in decreases in NOM (63% and 68% TOC) and HPO NOM (56% and 68%TOC) which helped to reduce fouling. However, the remaining NOM and HPO NOM still caused significant hydraulically and chemical irreversible fouling. The water pre-treated with floatation produced the least severe hydraulically irreversible fouling for all experiments while Raw ORW produced the highest. During the early stages of membrane filtration (~10 hours), the TMP sharply increases which may imply that adsorption is dominant. Statistical analysis during the initial stages of filtration showed that the HPO fraction of NOM was linked to hydraulically irreversible fouling, which may be attributed to adsorption. Raw ORW also had the highest hydraulically reversible fouling while all pre-treatments were able to reduce this type of fouling. Statistical analysis suggested that the transphilic (TPI) fraction of NOM and particulate organic carbon (POC) were responsible for hydraulically reversible fouling during subcritical flux experiments, which may be attributed to cake formation on the membrane surface. It was found that for all waters and experiments, hydraulically irreversible fouling was greater than hydraulically reversible fouling. This may be because of the high HPO concentrations in the ORW. Hydraulically reversible fouling and backwash efficiencies were found to fluctuate with time. It is hypothesised that the cake formation adheres to the membrane surface and is not fully removed until enough backwash pressure has developed. Further investigation into alternative cleaning procedures is required as the NaOH cleaning was not very effective for some of the pre-treated waters.

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35

Li, Hong-yu Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Mechanism studies for crossflow microfiltration with pulsatile flow." Awarded by:University of New South Wales. Graduate School of Biomedical Engineering, 1995. http://handle.unsw.edu.au/1959.4/17858.

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The mechanism of how pulsatile flow affects flux behaviour in crossflow micro-filtration was investigated. The effects of pulsatile flow were sub-divided into shear effects and backflushing effects. A servo-valve hydraulic piston pump was applied to generate pulsatile flows in the membrane module with particular waveforms. Four types of fluid pulsation with specific flow-rate and pressure waveforms were produced for experimental tests. Two parameters, /dVcf\dt/ maxand Pmin, were examined independently for their effect during pulsatile flow, which was estimated by comparing the cake resistance during steady flow and pulsatile flow at the same mean crossflow velocity, trans-membrane pressure and membrane resistance. Filtration tests for all the pulsatile flows with clean water confirmed that pulsatility only affects cake depositions. Without particles, no flux improvement was obtained. The results for the microfiltration of 0.5g/1 silica suspension showed that for pulsatile flows without backflushing (i.e. no negative transmembrane pressure peak), the fluid pulsation decreased cake resistance when the shear related parameter /dVcf\dt/max exceeded a critical value for each given waveform. When the instantaneous transmembrane pressure reached negative values, i.e. back-flushing occurred, the cake resistance was reduced for all pressure waves tested. Cake resistance was reduced more for more negative P min. With two of the waveforms tested, the cake resistance was almost completely eliminated. In contrast, the shear affected cake resistance reduction differently for each waveform. Comparing cake reduction results for different pulsatile waveforms, it was found that, for the square wave, the cake resistance reduction was higher for both shear and backflushing effect tests, while for the short spike waveform, the cake resistance reduction was lower. The flux waveforms were seen to follow the variations in transmembrane pressure. The flux response time was longer than the time required for the pressure changes, but was not dependent on the direction of the pressure change.

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36

Hadj, Said Aissa. "Etude des phénomènes limitant la clarification des jus de fruits par microfiltration tangentielle : application au jus de pommes." Toulouse, INPT, 1989. http://www.theses.fr/1989INPT019G.

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Les techniques a membranes se developpent rapidement dans les industries agro-alimentaires. Apres l'industrie laitiere qui constitue actuellement le principal secteur d'applications, le secteur des boissons est de plus en plus concerne par ces nouvelles techniques pour la clarification ou la concentration. Lors de la clarification des jus de pommes par microfiltration tangentielle, le phenomene limitant est lie essentiellement a la presence d'une fraction colloidale (notamment des pectines). L'etude systematique de la microfiltration tangentielle sur membrane organique de solutions de pectine confirme cette analyse. Les essais realises sur des suspensions synthetiques et sur des jus de pommes permettent d'evaluer l'importance des phenomenes de polarisation de concentration dans les mecanismes qui conduisent a la limitation du flux de filtrat. Un modele a ete propose pour rendre compte de la variation du flux de filtrat en fonction du temps decroissance initiale suivie d'une stabilisation. L'un des parametres du modele peut etre mis en relation avec la concentration en colloides dans le jus, le second avec la valeur du flux stabilise, le troisieme avec le temps de stabilisation. L'equation obtenue peut donc etre utilisee pour optimiser un cycle de filtration-decolmatage de facon a atteindre le meilleur compromis entre le flux du filtrat et les caracteristiques du produit

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37

Negrel, Jean-Luc. "Membrane protéique de nanofiltration : élaboration, caractérisation et propriétés de transfert." Montpellier 2, 1995. http://www.theses.fr/1995MON20065.

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Un nouveau type de membrane organo-inorganique de nanofiltration obtenue par depot de proteines sur une ceramique poreuse est presente. Le travail consiste a rechercher son protocole d'elaboration selon un critere de retention maximale puis a etudier ses proprietes a l'aide de modeles classiques. Le protocole d'elaboration comprend un conditionnement du support ceramique par filtration tangentielle d'une solution proteique (ici de la gelatine) suivi d'une modification du depot forme par traitements chimique (ici un tannage au formol) puis thermique. La membrane a ete caracterisee en permeation et en retention avec des solutions aqueuses de solutes de masses molaires connues. L'exploitation des resultats a permis de montrer principalement que, d'une part, le rayon moyen de pore est voisin de 2 nanometres, ce qui correspond a un seuil de coupure de 2 kg/mol, d'autre part, la permeabilite a l'eau est bien superieure a celle des membranes de nanofiltration classiques ce qui permet de travailler dans des conditions de faible depense energetique. La membrane offre une bonne reproductibilite des resultats. La couche proteique qui la constitue est tres mince, de structure resserree et uniforme, resistante aux attaques chimiques et biologiques. De plus le support est regenerable par application de cycle de lavage avec des solutions acide et basique. Enfin elle est biocompatible donc d'interet certain pour le domaine des bioindustries. Le protocole developpe devrait pouvoir etre applique a la fabrication de membranes presentant d'autres fonctions (catalyse, separation specifique,. . . )

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38

Xu, Zitong. "Removal of Heavy Metal Ions from Aqueous Solution by Alkaline Filtration." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40105.

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An innovative approach for the removal of heavy metal ions such as Pb2+ and Cd2+ from aqueous solution was evaluated. It was established that alkaline filtration, which is in essence the combination of alkaline precipitation and membrane filtration, could drastically increase both the efficiency and completeness of Pb2+ or Cd2+ ions removal, producing water whose metal concentration satisfying drinking water standard from a simulation wastewater containing 5 ppm or more Pb2+ or Cd2+ ions. Filtration with three different membranes, including microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) membranes, were studied at three different pH levels, i.e., 7.0, 8.5, and 10, in terms of metal ion rejection, flux, and permeate pH and at varied dissolved inorganic carbon (DIC) concentration. Increasing the pH of the feed in the tested range would lead to the decrease of metal ion concentration in permeate while flux was in general unaffected. When the feed pH was 10, the Pb2+ concentration in permeate was below 10 ppb regardless of the DIC concentration and membrane for filtration. The effects of DIC concentration were significant but complex. It was found that MF, UF, NF could all effectively reject Pb2+ ions at pH 8.5 and pH 10 although only NF was charged. A hypothesis was proposed to explain the mechanism of alkaline filtration based on experimental data.

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39

Santiwong, Suvinai Rensis Civil &amp Environmental Engineering Faculty of Engineering UNSW. "Analysis of compressible cake behaviour in submerged membrane filtration for water treatment." Publisher:University of New South Wales. Civil & Environmental Engineering, 2008. http://handle.unsw.edu.au/1959.4/42611.

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In this study, Smiles?? sorptivity-diffusivity numerical analysis is demonstrated to offer a comprehensive description of dead-end constant-pressure compressible cake filtration for water treatment. In addition to providing an insight on filtration performance and cake behaviour in terms of cake hydraulic permeability and compressibility in good agreement with the results derived using Ruth??s conventional cake filtration theory, the sorptivity-diffusivity model can be used to gain further information on depth-dependent local cake properties and extend our knowledge on the effect of feed suspension conditions (including solution composition, coagulant dosage and mixing) on the characteristics of the particulate assemblages (including size, structure and strength). Feed suspension conditions and primary particle properties exert significant effect on the characteristics of particles in suspensions and the resultant particulate assemblages. In the non-coagulated latex systems, an increase in ionic strength resulted in a suppression of the electric double layer of latex particles as indicated by a significant drop in the zeta potential of the feed suspension which lead to a dramatic reduction in cake hydraulic permeability. In the non-coagulated montmorillonite systems, feed suspensions with high ionic strength (1 M Na+, 50 mM Ca2+ and 50 mM Fe2+) were associated with larger suspended solids which appeared to form assemblages with nematic structures that are denser yet more permeable when compared to those with low ionic strength (0.1 M Na+, 1 mM Ca2+ and 2 mM Fe2+) which appeared to form highly ??cross-linked?? voluminous honeycomb type gel of very low permeability. Pre-coagulation of latex and montmorillonite suspensions with Al-based coagulants (alum and ACH) both resulted in formation of very large flocs which subsequently formed highly permeable solid assemblages. In the latex systems, the ratio of optimal alum to ACH dose was approximately 5:1 on a total coagulant mass basis and 1.3:1 as Al while the ratio of optimal alum to ACH dose was as high as 22:1 on a total coagulant mass basis and 6:1 as Al in the montmorillonite systems. Although both alum and ACH resulted in comparable filtration performances, the distinction in Al concentration and results of local cake properties analysis indicated the presence of different cake structures presumably due to the formation of different Al species.

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40

Kumar, Shivendra. "An Analytical Index for Evaluating Low-Pressure Hollow-Fibre Membrane Systems." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/366948.

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Water and wastewater treatment through the use of membrane filtration technology is one of the processes utilised currently to meet the growing demand for water. While new technologies can harness water from various non-traditional sources such as oceans, there remains the possibility of making drinking water more expensive through the use of costly treatment equipment. To prevent this and ensuing catastrophes around the world, the water industry needs a strategy that keeps the price of water and price of products aiding in the treatment of water controlled into the future. The overall aim of this study is to develop an analytical index that could be used by the water industry to measure, monitor, and control the price of water. A structured method to evaluate membrane manufacturing costs against the lifetime performance of membranes was developed. The method was then extended and a costing model for the application of membrane in water and wastewater treatment plants was established. Thereafter, a software application was developed to aid in the implementation of the analytical index. The results indicate that, with a measurable index in place, the evaluation of technologies with respect to the cost of water production can be effectively carried out. Thesis (PhD Doctorate) Doctor of Philosophy (PhD) Griffith School of Engineering Science, Environment, Engineering and Technology Full Text

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41

Rouquié, Camille. "Microfiltration de jus de fruits et suspensions à base de fruits : faisabilité et performances d'une filtration par membranes immergées." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG041/document.

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La microfiltration est largement utilisée pour la clarification, la stabilisation et la concentration de nombreuses suspensions à base de fruits (jus de fruits, agro-déchets, vin, etc.). Malgré ses divers avantages, la microfiltration présente néanmoins un inconvénient majeur qui est le phénomène de colmatage qui s’installe pendant l’opération de filtration et entraîne une diminution de la perméabilité membranaire. Si de nombreux mécanismes de colmatage (adsorption, blocage de pores, etc.) sont observés pendant la filtration de suspensions polydisperses comme les jus de fruits ou certains coproduits liquides, le dépôt de particules sur la membrane est souvent supposé être le mécanisme limitant. La formation de ce dépôt est fortement dépendante de l’équilibre entre forces convectives (imposées par le flux de perméat), qui attirent les particules de la suspension à proximité de la membrane, et forces de rétrotransport, qui éloignent les particules de la surface membranaire. La stratégie la plus employée pour maitriser le colmatage membranaire par dépôt est la filtration tangentielle qui permet d’imposer de forts cisaillements à la surface membranaire qui favorisent les mécanismes de rétrotransport des particules. Si cette stratégie de maîtrise du colmatage est amplement utilisée à l’échelle industrielle pour la microfiltration des suspensions à base de fruits, elle nécessite des coûts d’investissement et de fonctionnement non négligeables qui limitent son implantation aux industries présentant de fortes capacités de production et d’investissement. Au regard de cela, l’utilisation d’une configuration de filtration à membranes immergées pour la microfiltration de suspensions à base de fruits pourrait être une alternative intéressante. Cette configuration repose sur l’immersion de la membrane (modules plans ou fibres creuses) dans la suspension à filtrer, et est associée à un mode de filtration externe-interne, frontal ou quasi-frontale. Si l’absence de conditions hydrodynamiques intenses au voisinage de la membrane est associée à des flux relativement bas, les nombreux avantages de ce mode opératoire (coûts de fonctionnement réduits, simplicité opérationnelle, forte compacité, etc.) pourraient favoriser son emploi par les petits producteurs de jus de fruits et/ou les industries de valorisation des coproduits présentant des capacités limitées d’investissement et enclins à minimiser leurs couts opérationnels. Ce travail a ainsi étudié pour la première fois la possibilité d’utiliser un tel système pour la microfiltration de suspensions à base de fruits variées (jus de fruits et coproduits vinicoles). Ce travail de thèse a ciblé ainsi plusieurs objectifs : (i) caractériser le potentiel et le comportement colmatant de suspensions à base de fruits, en lien avec les caractéristiques physicochimiques propres à chaque suspension et au regard de leur filtration par membranes immergées, (ii) étudier des performances d’un système de microfiltration de suspensions à base de fruits par membranes immergées, performances en termes de productivité et de sélectivité et enfin (iii) dégager des pistes de réflexion qui conduiraient à une choix pertinent de conditions de filtration (mode immergé ou tangentiel) pour un type de suspension ciblé. Ce travail fournit ainsi des résultats d’identification de paramètres physico-chimiques clefs qui pourraient constituer un premier guide pour le choix de la configuration membranaire la plus adaptée au produit, permettant d’assurer une productivité acceptable lors de la microfiltration de suspensions à base de fruits Microfiltration is widely used to ensure clarification, stabilization, and concentration of various fruit-based suspensions (e.g. fruit juices, food by-products, wine). However, the performances of membrane filtration remain highly challenged by membrane fouling. During microfiltration of polydisperse suspensions, such as fruit-based suspensions, membrane fouling is generally associated to the deposition of particles on the membrane layer. This type of fouling is mainly governed by the equilibrium between convective forces (permeate flow), leading particles to flow towards the membrane, and back-transport forces, removing particles away from the membrane surface. The filtration performances depend strongly on this equilibrium, which is mostly governed by the hydrodynamic conditions of the filtration process and the particles size distribution of the suspension. In food industries, cross-flow microfiltration is generally used to limit membrane fouling. In this configuration, high cross-flow velocities are applied in order to enhance the back-transport forces limiting the deposition of foulant materials on the membrane surface. However, this working mode is well known to be highly energy consuming and might not always be relevant depending on the suspension characteristics. In the light of this, using immersed membranes configuration for the microfiltration of fruit-based suspensions might be an interesting alternative, especially for small producers with limiting investment capacity. In this configuration, widely used in other fields, the membranes are immersed in the suspension and filtration is performed in operating conditions close to that of dead-end filtration with limited back-transport forces and low operating costs. However, the performances of this filtration configuration remain little studied for the microfiltration of fruit-based suspensions. In this respect, this work investigated for the first time the possibility of using immersed membranes configuration for the microfiltration of various fruit-based suspensions (fruit juices and winery byproducts). Firstly, a characterization of the fouling potential of various suspensions during their microfiltration using immersed membranes filtration was performed in relation with their physicochemical properties (particle size distribution). Then, this work allowed highlighting the promising performances of immersed membranes configuration when used for the microfiltration of fruit-based suspensions, in terms of productivity and in terms of selectivity (clarification, concentration of bioactive compounds). Finally, it allowed drawing preliminary results about the relation between the physicochemical characteristics of a suspension and its fouling behavior while using (i) immersed membranes filtration or (ii) conventional cross-flow filtration. These results might be of great interest for the identification of relevant physicochemical parameters to predict the usefulness of using high cross-flow velocity to prevent membrane fouling during the microfiltration of fruit-based suspensions

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Chan, Robert Chemical Engineering &amp Industrial Chemistry UNSW. "Fouling mechanisms in the membrane filtration of single and binary protein solutions." Awarded by:University of New South Wales. Chemical Engineering and Industrial Chemistry, 2002. http://handle.unsw.edu.au/1959.4/18832.

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In this study the fouling mechanisms of various microfiltration and ultrafiltration membranes were studied when subjected to crossflow filtration using various protein solutions. Experimentation was carried out using controlled flux experiments and fouling phenomena was investigated via the monitoring of the transmembrane pressure (TMP) and rejection. Electron microscopy was employed to study fouling on microfiltration membranes when single protein solutions were filtered while a novel method involving Matrix-Assisted Laser Desorption Ionisation Mass Spectrometry (MALDI-MS) was developed to qualitatively and quantitatively analyse mixed proteins fouled on ultrafiltration membranes. An apparent critical flux was identified whereby fouling was shown to occur at fluxes where there was no increase in TMP. TMP increase is one of the common indicators of fouling in controlled flux operation. Microfiltration experiments showed that the imposition of the apparent critical flux is accompanied by rapid increases in hydraulic resistance and the membrane wall concentration. Pore blockage and narrowing occurred at somewhat higher fluxes as indicated by increases in the observed rejection. Fouling was not influenced greatly by the addition of electrolytes for microfiltration membranes but observed transmissions were found to be greater than 100% when ultrafiltration membranes were employed. For all membranes used, the actual value of the apparent critical flux was shown to be independent of the salt concentration but dependent on pH. Sub apparent-critical constant flux microfiltration showed the existence of an aggregation/deposition time lag after which the membrane experiences a rapid increase in resistance due to protein aggregates blocking a majority of pores. This phenomenon was shown to be dependent on pH and ionic strength and was concluded to be the product of a balance between electrostatic, solubility and hydrophobic interactions.

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43

Ferlita, Russell Rosario. "In Situ Biofiltration of Dissolved Organic Carbon in Reverse Osmosis Membrane Filtration." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3101.

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Biofouling, or the formation of biofilm on membrane surfaces, can decrease the performance (decreased flux and/or increased operating pressure) of a reverse osmosis (RO) membrane system in a water treatment plant. However, biofilms have been used in water treatment systems to remove organic carbon from water via biofilters and successfully reduce biofilm growth downstream. This research investigates the possibility that the heterotrophic biofilm present on membrane surfaces removes nutrients from the treatment water, thereby making it nutrient deprived as it travels along the treatment train. This may potentially be exploited as an in situ biofilter to actively remove dissolved organic carbon (DOC) from the treatment water, thereby protecting downstream membrane surfaces from biofouling. Analysis of fouled membranes from the Dunedin water treatment plant in Dunedin, FL indicates the presence of biofilm on membrane surfaces in a gradient pattern with a higher level of fouling at the front of the element. Additionally, the community structure of the biofilm at the front of the element is unique with respect to the feed-water and downstream membrane material. Additionally, a carbon (and nitrogen) mass balance study was performed at the water treatment plant in Dunedin, FL through extensive sampling of DOC at multiple locations of the RO membrane system over a 20 month period. Plant-level mass balance results indicate a significant pool of DOC was consistently unaccounted for, and presumably assimilated or otherwise removed within the membrane system. Sampling also indicated a removal of total nitrogen. Additionally, the specific UV absorbance (SUVA) of the DOC in concentrate was consistently greater than that of the feed water, suggesting the removal of labile aliphatic carbon as the feed water travels through the feed channel of the membrane system. A pilot system was designed and built to operate under plant conditions (flow rate and pressure) to test if the biofilm on the surface of the membrane can have a protective effect for downstream membrane material. A fouled membrane element was pulled from the plant at the same time and general location as an autopsied element (to determine composition on the surface) and used in the pilot system. Feed and concentrate water from the pilot was directed to flat sheet modules for performance testing and surface characterization. This allowed for characterization of the two sections without disturbing the membrane element. Differences in performance and foulant deposition were characterized for the two sections as a function of carbon addition and flow rate. The results from this testing suggest the membrane element, or the biofilm on its surface, has both a performance and a foulant deposition benefit for downstream membranes as compared to feed membrane material. This benefit also displayed an increasing trend as the concentration of organic carbon fed into the system increases.

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44

Pritchard, Mark. "The influence of rheology upon mass transfer in cross-flow membrane filtration." Thesis, University of Bath, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278262.

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45

Ponnumallayan, Prasanna. "Development of a novel stimuli responsive filtration membrane using self-assembling peptides." Thesis, University of Canterbury. Department of Chemical and Process Engineering, 2014. http://hdl.handle.net/10092/11032.

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Membrane based separation of specific constituents from a complex mixture is a wellestablished technology. Numerous filtration membranes have been developed for separations based on size, charge and hydrophobicity. Alternatively, synthetic membranes have been modified using various materials (e.g. charged polymers), to induce stimuli responsiveness and achieve specific separation goals. However, controlling finer separations based on more complex properties has been a challenge. Further improvements in separations could be made with a universal membrane that could be used for a wide range of applications. This thesis describes the development of a novel stimuli-responsive membrane whose pores and surface are functionalised with self-assembling peptides (SAPs). SAPs are molecules that spontaneously organize into ordered structures through non-covalent interactions, in response to external stimuli. The use of reversible SAPs to control membrane permeability could possibly result in a more effective separation process, whereby a condition such as pH could be used to enable or block passage of certain solutes through the membrane. To progress towards achieving this goal, the following sub-objectives were addressed, i) to identify a suitable reversible SAP and examine the effect of conjugating it with a poly(ethylene glycol) (PEG) polymer spacer on self-assembly, ii) to functionalise a membrane surface and subsequently tether the SAP via the spacer molecule, whilst retaining the self-assembling behaviour on the membrane surface. Initially, peptide P11-4 (QQRFEWEFEQQ) was chosen as the candidate for membrane tethering, because it can spontaneously switch molecular conformation from random coil at high pH to β sheet at low pH. P11-4 was conjugated to a 2 kDa N-hydroxy succinimideactivated PEG via N-terminal amine coupling to form P11-4-PEG-2K and the conjugation was validated using MALDI-tof spectrometry. However, P11-4-PEG-2K did not retain self-assembly of the peptide P11-4 but instead retained its random coil structure at pH < 3, in contrast to the behaviour of native P11-4, which formed β sheets at similar pH. P11-4-PEG- 2K retained its random coil conformation across various pH conditions (pH 2.5, 7 and 11) and incubation periods (2 min-20 days). Additional investigations on the effect of unreacted free PEG on P11-4 self-assembly indicated that the presence of free PEG in solution did not hinder self-assembly. Further, conjugation carried out in 3 mM sodium phosphate buffer and water also resulted in P11-4-PEG-2K that lost its ability to form β sheets at pH 2.5. Thus, P11-4-PEG-2K was deemed unsuitable for membrane modification and an alternative peptide EL-5F (ELELELELELF), with pH responsiveness, was used for further investigations on bioconjugate self-assembly in solution and upon being tethered to a membrane surface. For the first time, rapid and reversible pH-regulated self-assembly of EL-5F and its conjugates with 2 and 5 kDa PEG (EL-5F-PEG-2K and EL-5F-PEG-5K) was demonstrated. Circular dichroism indicated the formation of β sheet structures at pH < 5.9, 5.8 and 5.4 and disassembly to random coils above those pH values for EL-5F, EL-5F-PEG-2K and EL-5FPEG- 5K, respectively. β sheets were confirmed by the thioflavin T assay and transmission electron microscopy revealed the existence of extended fibrillar structures below the above pH values. pH-induced secondary structure conversion in both directions was reproducible for over fifteen cycles, even at salt concentrations of up to 200 mM NaCl, and the amounts of  sheet formed were quantitatively related to pH below the transition points. Self-supporting hydrogelation after self-assembly was observed at concentrations as low as 0.2 wt%, which is 15-fold lower than previously reported concentrations with PEGylated SAPs. Subsequent work, involving tethering of EL-5F-PEG-2K to an Anodisc alumina membrane surface and/or pores and investigations on the effect of reversible self-assembly on the permeability of the membrane was carried out. COOH groups were immobilised on the membrane surface to prepare it for the coupling of EL-5F-PEG-2K, using multilayer deposition of poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH). EL-5FPEG- 2K was then successfully amine-coupled to the COOH groups on the surface and this was confirmed using ATR-FTIR. Subsequent flux tests indicated no pH-dependant variation in buffer flux properties of the EL-5F-PEG-2K modified membrane. However, MWCO experiments using 72 and 29 kDa PEGs indicated reversible self-assembly of membrane tethered EL-5F-PEG-2K, upon changes in pH, thereby affecting macromolecule permeation. Furthermore, investigations on the reversible, pH-regulated self-assembly of peptide EL-5F and conjugate EL-5F-PEG-2K tethered to polystyrene nanoparticle (NP) surfaces, showed size transitions and aggregation of NPs upon changes in pH, indicating retention of peptide and bioconjugate self-assembly after surface tethering. The results provide a tentative but consistent proof-of-concept, giving the first steps towards the development of a novel switchable SAP-based, stimuli-responsive membrane. Further investigations suggested to validate reversible peptide self-assembly on the membrane surface, are expected to pave the way towards achieving finely controlled membrane separations.

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Lin, Changlong, and 林昌隆. "Chemical Treatment and Membrane Filtration of Fluoride-containing: Chemical Treatment and Membrane Filtration of Fluoride-containing." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/91713972744488096628.

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碩士 國立交通大學 環境工程所 91 The treatment of the fluoride-containing wastewater and the enormous amount of sludge generated has been a challenge for the HSIP. Fluoride-containing wastewater is generated during the etching and clean processes of semiconductor production. The range of fluoride concentration is usually between 200 and 500 mg/l. However, concentrations as high as 1000 to 2000 mg/l have been reported. In Taiwan, the most popular way of treating the fluoride-containing wastewater is the precipitation/coagulation/sedimentation process. The fluoride is first precipitated as calcium fluoride at pH around 8.0 to 8.5. Because of its small size, calcium fluoride particles are hard to remove by sedimentation. In this study, two methods for improvement were experimented. In the first method, the fluoride is removed from the liquid phase through a co-precipitation of “Calcium carbonate-Calcium fluoride”. The second method uses membrane filtration of the coagulated calcium fluoride particles. Optimum dosages of calcium salt and sodium carbonate and the optimum Ca/F molar ratio were determined. The dosing sequence and optimal pH were evaluated through the particle size and its settleability. The following are concluded from the six procedures tested: the pH must first be adjusted to 8, the carbonate must be added before the calcium chloride and its dosage must be adequate to avoid affecting the pH of the reaction. The suspensions were then coagulated with the PACl before the dead-end filtration through a 0.5μm MF membrane. The effects of the coagulant dosage, pH, and the permeate flux on the performance of solid/liquid separation were evaluated.

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Pickering, Karen Dunphy. "A cost model for membrane filtration." Thesis, 1992. http://hdl.handle.net/1911/13629.

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A model is developed that calculates capital and operating cost of cross-flow membrane filtration as a function of relevant design parameters. An expression for capital cost is empirically derived from information gathered from membrane manufacturers. Operating cost is divided into components for energy consumption, chemical demand, membrane replacement and concentrate disposal and is determined from attributes of the membrane system. The effect of operating parameters and membrane characteristics on cost are examined. The flux of permeate across a membrane is the principle factor determining cost. Energy cost, although important to the daily operating cost of a water treatment plant, is overshadowed by the membrane replacement cost. The effect of backflushing procedures on cost is evaluated using empirical functions for permeate flux derived from a microfiltration pilot study. Microfiltration is determined to be a cost-competitive alternative to ultrafiltration. Costs calculated by this study are compared to reported costs for membrane filtration.

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Bernardy, Jeffry A. "Cannery waste management using membrane filtration." 1990. http://catalog.hathitrust.org/api/volumes/oclc/23113829.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1990. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 77-85).

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Ye, Yun. "Macromolecular fouling during membrane filtration of complex fluids /." 2005. http://www.library.unsw.edu.au/~thesis/adt-NUN/public/adt-NUN20051020.123104/index.html.

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Boyle, Paul Martin. "A Refined Parallel Simulation of Crossflow Membrane Filtration." Thesis, 2011. http://hdl.handle.net/1911/64390.

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This work builds upon the previous research carried out in the development of a simulation that incorporated a dynamically-updating velocity profile and electric interactions between particles with a Force Bias Monte Carlo method. Surface roughness of the membranes is added to this work, by fixing particles to the membrane surface. Additionally, the previous electric interactions are verified through the addition of an allrange solution to the calculation of the electrostatic double layer potential between two particles. Numerous numerical refinements are made to the simulation in order to ensure accuracy and confirm that previous results using single-precision variables are accurate when compared to double-precision work. Finally, the method by which the particles move within a Monte Carlo step was altered in order to implement a different data handling structure for the parallel environment. This new data handling structure greatly reduces the runtime while providing a more realistic movement scheme for the particles. Additionally, this data handling scheme offers the possibility of using a variety ofn-body algorithms that could, in the future, improve the speed of the simulation in cases with very high particle counts.

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