29 research outputs found
CaractĂ©risation de filtrabilitĂ© par la filtration centrifuge â CEFU
Il existe une grande diversitĂ© des techniques pour la mesure de la filtrabilitĂ© de suspensions. Cependant, les techniques existantes ne sont pas adaptĂ©es Ă la caractĂ©risation rapide dâun grand nombre de petits Ă©chantillons (surtout, des Ă©chantillons liquides).Depuis quelques annĂ©es lâUniversitĂ© Technologique de CompiĂšgne et la sociĂ©tĂ© LUM GmbH travaillent sur le dĂ©veloppement de la centrifugation analytique pour la caractĂ©risation accĂ©lĂ©rĂ©e de la filtrabilitĂ© des suspensions et dispersions. La mĂ©thode consiste Ă rĂ©aliser des essais de filtration Ă lâaide de la centrifugation analytique puis Ă analyser les courbes de la filtration centrifuge obtenues pour en extraire des propriĂ©tĂ©s des solutions.La comparaison simple des courbes de filtration obtenues permet de classifier les Ă©chantillons selon leur filtrabilitĂ©. De plus, lâanalyse des courbes de filtration permet la caractĂ©risation quantitative de la filtrabilitĂ© : dĂ©termination de la rĂ©sistance de la membrane colmatĂ©e, de la rĂ©sistance spĂ©cifique du gĂąteau et des propriĂ©tĂ©s de rĂ©versibilitĂ© de la compression du gĂąteau. La mĂ©thode dâanalyse des donnĂ©es dĂ©pend de la nature des Ă©chantillons : deux mĂ©thodes adaptĂ©es pour des suspensions concentrĂ©es et des solutions des colloĂŻdes sont validĂ©es actuellement .Le congrĂšs MemPro6 sera lâoccasion de prĂ©senter les rĂ©sultats les plus rĂ©cents sur lâultra- et la microfiltration centrifuge pour la caractĂ©risation de la filtrabilitĂ© des solution
Dairy industry and animal products processing applications
Over the past 30 years, the worldwide market for the membrane operations in the food industry increased to a market volume of about 800-850 millions ⏠(Lipnizki, 2010). It then becomes the second biggest market for membranes after water and wastewater treatment. This chapter will give an outlook of potential membrane applications in dairy and animal products processing. The first part of this chapter will focus on the dairy industry, the largest and most developed membrane market in the food sector, which has most successfully been able to put membranes to work for the benefit of the industry and its customers. The dairy sector encompasses a large variety of different products and membrane processes, and this chapter will give an overview of the most familiar and successful applications implemented throughout the processing chains (from the product reception to the waste-water treatment). Then the chapter will present other established applications in the egg processing industry and other animal products processing, such as seafood, blood and gelatin processing
Concentration en lipides polaires de babeurres
Concentration en lipides polaires de babeurres. Journée de restitution du programme de recherche VALOBAB VALOrisation durable du BABeurr
High through analytical centrifugal ultrafiltration for characterization of filterability and membrane fouling
The laboratory technique of analytical photocentrifugation is based on continuous measurement of spatially resolved light transmission profiles during centrifugation over the whole sample length. Evolution of light transmission profiles during phase separation induced by centrifugation (sedimentation, consolidation, creaming, etc.) provides direct information about sample stability and aggregation state without sample dilution. In addition, different methods of analysis are available in order to relate light transmission profiles evolution with sample properties (as particle size distribution, phase volume fraction, permeability and compressibility for particulate samples).Commercially available analytical photocentrifuges (LUMiFuge and LUMiSizer, LUM GmbH) allow simultaneous automated analysis of up to twelve different samples in a single centrifuge run. They require small sample volume (up to 2 ml) and allow performing centrifugal filtration experiments (with special centrifugal filtration modules, LUM GmbH). This makes analytical photocentrifuges high throughput equipment for laboratory analysis of dispersion properties (including filterability in cake filtration and membrane ultrafiltration).This paper aims at latest development of analytical photocentrifugation fordirect characterization of ultrafiltration of colloidal samples. It summarizes two recently proposed methods of centrifugal ultrafiltration (model, experimental protocols and data analyses). Common features of these methods are the small sample volume and simultaneous analysis of different samples.Centrifugal ultrafiltration experiments were performed by the analytical photo-centrifuge LUMiSizer equipped with centrifugal filtration modules (LUM GmbH).The applicability of analytical photocentrifugal ultrafiltration for characterization of colloids filterability and membranes fouling was demonstrated on example of aqueous bovine serum albumin solutions (0.05â0.9 wt.%) and laponite suspension (0.3 wt.%) using polyethersulfone ultrafiltration membranes with different molecular weight cut-offs (1â30 kDa). Analysis of centrifugal ultrafiltration curves allowed determination of fouled membrane resistance as well as pressure dependency of specific cake resistance of studied colloids
On the cohesive properties of casein micelles in dense systems
Milk casein micelles are natural colloids that behave as microgel particles. When concentrated, those particles form cohesive gels, the properties of which are still largely unknown. With this work, the objective is to bring new information about the origin of gel cohesion in such a packing of soft colloidal objects. The experimental approach is based on the following of the reswelling/redispersion behavior of concentrated gels prepared through osmotic stress under variable controlled conditions (compression degree, compression route, and duration) and subsequently immersed in a native solvent. The essential result is that gel cohesion strongly depends on the initial deformation of the casein micelles within the gels. The optimum of gel cohesion if found for intermediate deformations, i.e. , when the micelles have lost about half of their original volume. Below that deformation, the contact between neighboring micelles is probably too weak, so that the repulsion/attraction balance is still in favor of inter-micellar brushrepulsion forces. Above that deformation, the gel also loses its cohesiveness, either because some hy-drophobic inter-micellar connections are lost during thefirst stage of redispersion (individual micellarreswelling), or because there are simply less cohesive bonds at such high compression level
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LâĂ©limination du dĂ©pĂŽt de filtration par rinçage et nettoyage des membranes est une essentielle pour assurer lâefficacitĂ© de la filtration efficace. Pourtant, on trouve que la discussion actuelle des diffĂ©rents mĂ©canismes, qui conduisent Ă lâĂ©limination du dĂ©pĂŽt aprĂšs la filtration (gonflement, Ă©rosion, dĂ©tachement, âŠ), est loin dâĂȘtre exhaustive. Pour cette raison nous avons consacrĂ© ce travail Ă la modĂ©lisation du comportement du dĂ©pĂŽt de filtration rĂ©versible pendant la relaxation de la pression aprĂšs filtration sur membrane.Lâobjectif de ce travail est de dĂ©crire la cinĂ©tique du gonflement dâun dĂ©pĂŽt de particules colloidales en prenant en compte la rĂ©sistance hydraulique de la membrane de filtration, et dâĂ©tudier lâinfluence du gonflement de ce dĂ©pĂŽt sur son Ă©limination de la surface de la membrane.La thĂ©orie de filtration-consolidation a Ă©tĂ© adaptĂ©e pour la description du gonflement. Les valeurs des caractĂ©ristiques du dĂ©pĂŽt (compressibilitĂ©, filtrabilitĂ© (rĂ©sistance spĂ©cifique) et Ă©paisseur du dĂ©pĂŽt), ainsi que les paramĂštres opĂ©ratoires (rĂ©sistance hydraulique de la membrane, pression transmembranaire appliquĂ©e) utilisĂ©es pour la modĂ©lisation Ă©taient choisies pour ĂȘtre reprĂ©sentatives de lâultrafiltration dâune suspension colloĂŻdale avec une forte compressibilitĂ© rĂ©versible de dĂ©pĂŽt.Il a Ă©tĂ© dĂ©montrĂ© que le gonflement dâun dĂ©pĂŽt rĂ©versiblement compressible peut ĂȘtre assistĂ© par lâabsorption du filtrat Ă travers la membrane (Fig. 1). Cet effet est expliquĂ© par la relaxation de la pression de solide aprĂšs la rĂ©duction de la pression transmembranaire appliquĂ©e. Plus la rĂ©sistance hydraulique de la membrane est faible (forte permĂ©abilitĂ© de la membrane), plus lâabsorption du filtrat et la vitesse de gonflement du dĂ©pĂŽt augmentent.Lorsque la rĂ©sistance hydraulique de la membrane est faible et la rĂ©sistance hydraulique du dĂ©pĂŽt est forte, lâabsorption du filtrat au travers la membrane peut conduire Ă une distribution non-uniforme de la concentration du solide dans le dĂ©pĂŽt gonflĂ© : le modĂšle prĂ©dit une distribution en forme de cloche (Fig. 2a). A la membrane, lâadhĂ©sion du dĂ©pĂŽt diminue avec la diminution de la concentration locale, et la faible concentration en solide dans le dĂ©pĂŽt (distribution en forme de « cloche ») peut faciliter son Ă©limination de la surface de la membrane. Donc, un dĂ©pĂŽt dont les propriĂ©tĂ©s de compressibilitĂ© sont rĂ©versibles peut ĂȘtre facilement Ă©liminĂ© de la surface dâune membrane ayant une faible rĂ©sistance hydraulique, avant la fin du gonflement. En revanche, le gonflement du mĂȘme dĂ©pĂŽt Ă la surface dâune membrane peu permĂ©able (rĂ©sistance hydraulique Ă©levĂ©e) est plus lent, et conduit Ă une distribution monotone de la concentration du solide (la concentration est la plus Ă©levĂ©e Ă lâinterface dĂ©pĂŽt-membrane, Fig. 2b). Dans ce cas le dĂ©pĂŽt sâĂ©limine de la membrane aprĂšs la fin du gonflement.Ces phĂ©nomĂšnes doivent ĂȘtre pris en compte dans la planification des expĂ©rimentations et les analyses des rĂ©sultats de filtration qui sâintĂ©ressent Ă lâĂ©tude de la force dâadhĂ©sion du dĂ©pĂŽt Ă la membrane
Caractérisation des couches de protéines accumulées lors des opérations de filtration et diffusion de rayons X (INRA en lumiÚre 5 ans de partenariat avec soleil)
il s'agit d'un type de produit dont les mĂ©tadonnĂ©es ne correspondent pas aux mĂ©tadonnĂ©es attendues dans les autres types de produit : REPORTThe formation of concentrated layers of proteinsat the membrane surface during filtrationwas followed using small angle X-ray scatteringon the SWING beamline. It allowed to followboth the concentration profiles ( and theirreversibility ) in the course of time with a resolutionof 50 ÎŒm and the structural modificationsof the proteins in the concentrated layers.L'Ă©tablissement de couches concentrĂ©es deprotĂ©ines Ă la surface des membranes encours de filtration a Ă©tĂ© suivi par diffusion derayons X aux petits angles ( SA XSâ) sur la lignede lumiĂšre SWING. Cela a permis d'une partd'accĂ©der aux profils de concentration et Ă leur rĂ©versibilitĂ© au cours du temps avec unerĂ©solution de 50 ÎŒm, et d'autre part de suivreles modifications structurales des protĂ©inesdans ces couches
Diafiltration of skimmed milk using polymeric spiral-wound microfiltration membrane: impact of solvent and diavolume ratio on the efficiency of protein separation
Microfiltration, MF is largely used in dairy industry to separate casein micelles from whey
proteins. The weak performances of polymeric membranes compared to ceramic membranes
are a restriction for their implementation in industry. Adding a diafiltration step is promising
to improve polymeric MF performances, however most of the works have focused on the
hydraulic performances and few have investigated the repercussion of diafiltration on protein
separation. This work aims at investigating the impact of both the nature of solvent and the
diavolume ratio on the MF efficiency.
Pilot-scale MF using polymeric membrane (Synder, 800 kDa) was carried out on thermized
skimmed milk at 12 °C with a volume reduction ratio, VRR from 2.5 to 3.2 and a
transmembrane pressure of 0.7 bar. Continuous diafiltration was performed using reverse
osmosis water (ROW) or milk ultrafiltrate (PUF). Permeation flux and ÎČ-lactoglobulin
transmission were evaluated.
During PUF-diafiltration of VRR-2.8-retentate, permeation flux is stable and ÎČ-
lactoglobulin transmission declines by 26 % after 4.8 diavolumes. During ROW-diafiltration,
permeation flux increases linearly until 2.9 diavolumes, then reaching an upper value.
Simultaneously ÎČ-lactoglobulin transmission follows a parabolic curve with a maximum
increase of 68 % for VRR-3.2-retentate and 10 % for VRR-2.5-retentate. According to Darcyâs
law, the reduction of permeate viscosity during ROW-diafiltration leads to the improvement of
permeation flux. This behavor is accentuated by the fouling layer relaxation consequent to the
diminution of the ionic strength. In case of high repulsive forces in the concentration layer (low
ionic strength), the transmission of negatively charged whey proteins is however restricted.
The decrease of protein concentration during diafiltration may also limit whey protein
transmission for high diavolume ratios.
Diafiltration using ROW is recommended to increase transmission of whey proteins.
However, volume of solvent has to be adapted to the VRR reached prior diafiltration to enable
an optimum transmissio
Modeling the filtration of soft and permeable colloids: the milk case study
Filtration operations (ultra-, microfiltration) are extensively used for concentrating or separating an evergrowingvariety of colloids. However, the phenomena that determine the performance of these operations,both in terms of permeability and selectivity, are not yet fully understood. This is especially the casewhen dealing with colloids that are soft and permeable. In this paper, we propose a universal approach forbuilding a model that is able to predict the performance (flux, concentration profiles) of the filtration ofsuch objects. This is done by focusing on the case of milk filtration; all experiments are performed withdispersions of milk casein micelles, which are "natural" colloidal microgels. Using this example, wedevelop the general idea that a filtration model can always be built for a given colloidal dispersion as longas this dispersion has been characterized in terms of osmotic pressure Î and hydraulic permeability k. Forsoft and permeable colloids, the major issue is that k cannot be assessed in a trivial way like in the casefor hard-sphere colloids. To get around this difficulty, two distinct approaches are followed to measure k :a direct approach, involving osmotic stress experiments, and a reverse-calculation approach, that consistsin estimating k through well-controlled filtration experiments. The resulting filtration model is validatedagainst experimental measurements obtained from combined milk filtration/SAXS experiments.Les opĂ©rations Ă membrane (ultra-, microfiltration) sont largement utilisĂ©es pour la concentration et le fractionnement de dispersions colloĂŻdales. Cependant les phĂ©nomĂšnes qui gouvernent les performances de ces opĂ©rations (permĂ©abilitĂ© et sĂ©lectivitĂ©) ne sont pas totalement compris. Câest particuliĂšrement le cas pour les colloĂŻdes dĂ©formables et permĂ©ables. Dans ce papier, nous proposons une approche universelle pour la construction dâun modĂšle permettant la prĂ©diction des performances (flux de permĂ©ation, profil de concentration) de la filtration de colloĂŻdes mous et permĂ©ables. La filtration du lait Ă©crĂ©mĂ© est pris comme exemple et les expĂ©riences sont rĂ©alisĂ©es avec des dispersions de micelles de casĂ©ines, qui sont considĂ©rĂ©es comme des colloĂŻdes naturels. En se basant sur cet exemple et sur le fait que chaque dispersion colloĂŻdale est caractĂ©risĂ©e par sa pression osmotique Î et sa permĂ©abilitĂ© hydraulique k, un modĂšle de filtration est proposĂ©. Pour des objets mous et dĂ©formables, la difficultĂ© majeure repose sur le fait que la permĂ©abilitĂ© dâobjets mous et poreux ne peut pas ĂȘtre Ă©valuĂ©e de maniĂšre triviale comme dans le cas de sphĂšres dures. Pour contourner cette difficultĂ©, deux approches ont Ă©tĂ© suivies pour dĂ©terminer k: une approche directe Ă partir des expĂ©riences de pression osmotique, et une approche « de calcul inverse », qui consiste Ă calculer k Ă partir dâexpĂ©riences de filtration bien contrĂŽlĂ©es. Le modĂšle ainsi construit est validĂ© avec des donnĂ©es expĂ©rimentales de profil de concentration obtenues dans des travaux ultĂ©rieurs, grĂące au couplage dâune cellule de filtration avec la diffusion de rayons X (SAXS)