Characterization of ultrafiltration membranes by tracer's retention:Comparison of methods sensitivity and reproducibility

Previous studies have shown that the absolute membrane cut-off and the value quoted by the manufacturers may be very different because of differences in methodologies and testing conditions. The origin of this discrepancy is often difficult to identify as the characterization method used by the membrane manufacturers is not specified. The goal of this study is to evaluate in terms of sensitivity, repeatability and reproducibility the methodologies used by a working group including membrane manufacturers, end-users and a research laboratory. The five selected membranes are hollow fibers used in drinking water production. They are made of various materials with different configurations (internal–external and external–internal type) and molecular weight cut-offs. Different types of tracers are used: dextrans, poly (ethylene glycol)s, poly(ethylene oxide)s, MS2 bacteriophage filtrated in single sized solution or in mixture. Results collected lead to a better understanding of the origin of discrepancies and allow to define the best operating conditions (tracer's type, working conditions range, data treatment methods,…) providing the most appropriate, accurate and reproducible testing protocol according to the selected application

Submerged membrane bioreactor for waste water treatment: determination of the shear stresses produced by coarse bubbles

Submerged membrane bioreactor for waste water treatment: determination of the shear stresses produced by coarse bubble

Rheological study of sludge of membranes bioreactors for water treatment: protocol, limitations and link with the filtration

The submerged membranes bio-reactors (sMBR) are more and more visible in the field of waste water treatment. The membrane fouling, that causes a drastic fall of the performances, can be limited by the application of a swarm of bubbles close to the membrane surfaces. This aeration as a major factor of the energetic expense of these processes, lets numerous studies to focus on the understanding of the mechanisms linking the bubbles swarm with fouling.. In this background, the rheological tools appeared to be useful to understand the behaviour of sludge under shear stress. In order to be sure to get significant results, we used three types of rheological measurements: i) the influence of shear rate on shear stress; ii) the influence of upward then downward stages of shear stress on viscosity; iii) the influence of the alternation of two stages of shear stress with implementation times identical to those of sMBR aeration. Besides a viscoplastic behaviour previously observed, a phenomenon of hysteresis appeared. The transparent upper plan used on the rheometer exhibited formations of aggregative structures “in roll”. Sludges of a sMBR using different sequencing of aeration are compared: the developed protocols enabled to differentiate those sludges, with characteristic results depending on mechanical applications. The aim of this work is, eventually, to propose some correlations between usual characteristics of the process and aeration operating parameters, in order to propose an aeration policy improving energetic performances

Innovate contactor for CO2 recovery

Innovate contactor for CO2 recover

Copolymère à blocs amphiphile et son utilisation pour la fabrication de membranes polymères et de filtration

L'invention concerne un copolymère à blocs amphiphile comportant au moins un premier bloc hydrophile susceptible d'être obtenu à partir de monomères d'acrylate de n-butyle et de méthacrylate d'hydroxyéthyle, et un deuxième bloc hydrophobe susceptible d'être obtenu à partir d'un monomère de méthacrylate de méthyle. Ce copolymère s'avère particulièrement avantageux pour une utilisation en tant qu'additif pour la fabrication d'une membrane polymère de filtration, notamment à base de PVDF, en particulier par un procédé d'inversion de phase

Abnormal splicing switch of DMD's penultimate exon compromises muscle fibre maintenance in myotonic dystrophy

International audienceMyotonic Dystrophy type 1 (DM1) is a dominant neuromuscular disease caused by nuclear-retained RNAs containing expanded CUG repeats. These toxic RNAs alter the activities of RNA splicing factors resulting in alternative splicing misregulation and muscular dysfunction. Here we show that the abnormal splicing of DMD exon 78 found in dystrophic muscles of DM1 patients is due to the functional loss of MBNL1 and leads to the re-expression of an embryonic dystrophin in place of the adult isoform. Forced expression of embryonic dystrophin in zebrafish using an exon-skipping approach severely impairs the mobility and muscle architecture. Moreover, reproducing Dmd exon 78 missplicing switch in mice induces muscle fibre remodelling and ultrastructural abnormalities including ringed fibres, sarcoplasmic masses or Z-band disorganization, which are characteristic features of dystrophic DM1 skeletal muscles. Thus, we propose that splicing misregulation of DMD exon 78 compromises muscle fibre maintenance and contributes to the progressive dystrophic process in DM

CONTRIBUTION A L'ETUDE DU TRAITEMENT DES EAUX PAR CONGELATION (POTENTIALITES ET APPLICATIONS)

TOULOUSE-INSA (315552106) / SudocSudocFranceF

Intrinsic Transgene Immunogenicity Gears CD8+ T-cell Priming After rAAV-Mediated Muscle Gene Transfer

International audienc

Etude de phénomènes induits par l’aération pour la limitation du colmatage dans les bioréacteurs à membranes pour le traitement des eaux usées

Dans le contexte des Bioréacteurs à Membrane immergés (BAMi) pour le traitement des eaux usées, le colmatage reste un verrou limitant. L’aération avec des grosses bulles (GB) utilisée en voisinage de la membrane pour limiter le colmatage engendre un coût de fonctionnement supplémentaire (Kraume et. Drews, 2010). Le séquençage de l’aération pouvant permettre à la fois de baisser le coût et de limiter le colmatage (Van Kaam, 2005), nous nous intéressons à comprendre les phénomènes impliqués afin de déterminer la meilleure politique de séquençage. Une hypothèse est qu’un débit d’aération trop fort favoriserait la rupture des flocs (Meng et al., 2008) ayant pour conséquences défavorables à la limitation du colmatage : 1- la diminution du diamètre des flocs, 2- l’augmentation des concentrations en substances polymériques extracellulaires (SPE) solubles par leur séparation des flocs. Le temps sans aération permettant la reformation des flocs avec la réintégration des SPE. L’objectif de ce travail est d’étudier l’effet de contraintes imposées en rhéomètre et en pilote au travers des liens entre les paramètres du procédé -séquençage de l’aération GB et évolution du colmatage mesuré par la variation de la pression transmembranaire (PTM)- et les grandeurs liées aux phénomènes de colmatage -contraintes de cisaillement générées par les bulles, taille moyenne des flocs et concentrations en SPE (protéines et sucres)-. Si, à l’échelle du procédé, l’influence de l’aération sur la taille des flocs et les EPS solubles est difficile à quantifier et imbriquée avec d’autres phénomènes, à une échelle plus locale et pour les contraintes de cisaillement imposées, l’influence de ces dernière sur la taille des flocs et sur les concentrations en ESP solubles viendrait confirmer l’hypothèse de la rupture des floc

Optimization of wastewater filtration process in submerged membrane bioreactors : applicability of a dynamic model to scale up.

Abstract. The application of a hybrid mathematical model, which takes into account the effect of main variables in Submerged Membrane Bioreactor (SMBR) systems, was established in order to simulate and optimize the FILTRATION process into SMBR, on the base of experimental data performed on a bench and pilot scale bioreactors. The validity of the numerical process in the scale up of the water treatment process was checked. Numerical simulations of the wastewater treatment process were performed in order to find the optimal filtration conditions for both different scale bioreactors. Various operating conditions (idlefiltration time, aeration intensity, solids retention time, hydraulics retention time, and total suspended solids concentration) were tested. Different optimization criteria were considered to minimize the transmembrane pressure and energy consumption, and to maximize filtrate flow