Articoli di riviste: "Filtration à flux tangentiel"

1

Serrano, Michel, Anne-Claire Vannier e Pascal Ribéreau-Gayon. "Clarification des vins par filtration en flux tangentiel (ultrafiltration). Incidence sur la composition chimique et les qualités organoleptiques. Evolution des produits au cours du vieillissement". OENO One 22, n. 1 (31 marzo 1988): 49. http://dx.doi.org/10.20870/oeno-one.1988.22.1.1256.

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Les auteurs étudient la clarification des vins en flux tangentiel avec un ultrafiltre pilote muni de membranes organiques. Les débits de perméat sont faibles (30 l x h-1 x m-2) mais le colmatage peu important. Les pourcentages de retentat sont peu élevés (0,3 à 0,7 %). Les produits ainsi clarifiés présentent de faibles turbidités et des indices de colmatage très bas. Cette technique entraîne une rétention importante des polysaccharides et des composés phénoliques des vins rouges. Les qualités organoleptiques sont légèrement affectées dans les premiers mois qui suivent l'opération, mais les différences entre les vins témoins et ultrafiltrés sont difficiles à détecter après douze mois de conservation des échantillons.+++Wine clarification with a tangentiel flux through a pilot ultrafilter with organic pads (breaking point 50,000 Daltons.) has been studied. Porosity is low (30 l x h-1 x m-2), but the blockage of the filter is hardly possible as the percentage of retentiveness is limited (0.3 % to 0.7 %). The finished wines thus clarified have a perfect sparkling clarity and a low blockage potential. The type of sterilization, however, used with this type of filter-pads made it impossible to obtain a complete erradication of all microorganisms in the filtrate. Close filtration has little influence on the aromatic flavours and aromas of white wines although macromolecules are highly affected. A 76 % to 88 % fall in the amount of polysaccharides may be observed. In the same way the phenolic compounds in red wines are affected. The more mature, the richer in alcohol and colour the wine is, the greater the effect of close filtration upon the wine; this may provoke a visible fall in the colour intensity. Close filtration improves tartric stability but has hardly any effect at all on protein stability in white wines. When applied to young wines, close filtration does not show a significant change in the organoleptic analysis compared to more traditional filtration processes, particularly when tasted after a six months period of ageing. When close filtration is applied to more mature wines, the organoleptic analysis may detect it during the first months after the filtration, but it tends to disappear and it is hardly traceable after a year or two. It is surprising to note that on such red wines the organoleptic analysis cannot detect the differences between two samples, one which had undergone close filtration and one which had not, despite a major changes in the chemical analysis particulary concerning the colour and the amount of polysaccharides.

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Ben Amar, R., E. Ellouze, B. B. Gupta e A. M. Ayad. "Traitement d'effluents de tannerie-mégisserie par microfiltration tangentielle". Revue des sciences de l'eau 14, n. 4 (12 aprile 2005): 445–64. http://dx.doi.org/10.7202/705427ar.

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Dans ce travail un procédé de traitement des effluents issus de l'unité de préparation des peaux des animaux au tannage (travail en rivière) en tannerie-mégisserie a été étudié en utilisant la technique de microfiltration tangentielle sur membrane minérale en céramique. Les performances de ce procédé en terme de flux de filtration et de rendement épuratoire dépendent aussi bien des paramètres hydrodynamiques de filtration que de la qualité des effluents (collectés en été et en printemps) issus des différents bains de traitement et de rinçage des peaux dans l'atelier de rivière. Le flux de filtration varie entre 15 l/h.m2 pour l'effluent de printemps et 90 l/h.m2 pour l'effluent d'été. Les paramètres hydrodynamiques optimaux ont également été déterminés: la vitesse de circulation U=3 m/s, la pression transmembranaire Ptm=2 bar et la température T=43°C. L'étude de la microfiltration à concentration variable conduit à des facteurs de concentration volumique (FCV) de 6,5 pour l'effluent de l'été et de 2,4 pour l'effluent de printemps.

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Charfi, A., J. Harmand, N. Ben Amar, A. Grasmick e M. Heran. "Deposit membrane fouling: influence of specific cake layer resistance and tangential shear stresses". Water Science and Technology 70, n. 1 (22 aprile 2014): 40–46. http://dx.doi.org/10.2166/wst.2014.186.

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Cake fouling is the leading cause of membrane permeability decrease when filtering mixed liquor suspension containing high suspended solid concentrations. A simple model is proposed to simulate the cake resistance evolution with time by considering a macro-scale fouling linked only to the accumulation of particles on the membrane surface. This accumulation appears as the difference between the flux of deposited particles due to the filtration and the flux of particles detached from the membrane surface due to the tangential shear stresses caused by recirculation flow in the sidestream membrane bioreactor (MBR) or gas sparging close to the membrane surface for submerged MBR configuration. Two determining parameters were then highlighted: the specific cake resistance and the ‘shear parameter’. Based on these parameters it is possible to predict model outputs as cake resistance and permeate flux evolution for short-time filtration periods.

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Lee, Jieun, Jiwon Na e Youngbin Baek. "Effects of Impurities from Sugar Excipient on Filtrate Flux during Ultrafiltration and Diafiltration Process". Membranes 11, n. 10 (11 ottobre 2021): 775. http://dx.doi.org/10.3390/membranes11100775.

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Sugar excipients such as sucrose and maltose are widely used for biopharmaceutical formulation to improve protein stability and to ensure isotonicity for administration. However, according to recent literature, pharmaceutical-grade sucrose contained nanoparticulate impurities (NPIs) that result in protein aggregation and degradation. The objective of this study was to evaluate the filtrate flux behavior of sugar solution during ultrafiltration (UF) and diafiltration (DF). Filtrate flux data were obtained using either a tangential flow filtration (TFF) system for DF experiments or a normal flow filtration system for UF experiments. In diafiltration experiments, which were performed using 7 g/L of human immunoglobulin G in a 20 mM histidine buffer with the 100 mM sucrose or maltose, the filtrate flux with sucrose solution decreased significantly. In contrast, the one with maltose solution was in good correspondence with the calculated filtrate flux accounting for the effects of solution viscosity. This large decline in the flux was also observed during UF experiments, in which the presence of NPIs was identified by dynamic light scattering analysis and by capturing an SEM image of the membrane surface after filtration. In addition, highly purified sucrose resulted in a much lower flux decline in TFF in the absence of NPIs. These results provide important insights into the factors governing the optimization of the UF/DF process using appropriate excipients for biopharmaceutical formulation.

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Sravan Kumar, Pillalamarri, Surabhi Goyal e Amit Kumar. "Process Validation of Tangential Flow Filtration System for High Yield Drug Substance of Vaccine". Journal of Pharmaceutical Quality Assurance and Quality Control 4, n. 1 (29 aprile 2022): 5–12. http://dx.doi.org/10.46610/jqaqc.2022.v04i01.002.

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Objective: The objective of this work is to prove and validate Tangential Flow Filtration System for high yield drug substance of vaccine as product and also to provide the experimental insight for vaccine industrial personnel to acquire the knowledge on the process validation of the system to obtain high and consistent yield of the product. Methods: The method in this work involves the experimental determination of the process parameters for Tangential Flow Filtration system such as Trans-membrane pressure and flux including validation of these parameters to achieve the high yield drug substance with consistency. The experiment entails the execution of three validation batches with different variables during the process and standardized at the point of maximum yield with similar reliability. Results: The performed validation of Tangential Flow Filtration system was so optimal and suitable for identification of parameters that controlled the yield of the drug substance consistently and validated accordingly. Statistical evaluation of the optimized parameters results from three consecutive batches was done and the mean was calculated individually as 0.25 bar for TMP, 0.4 LMH for flux and 402.6mg/mL for drug substance yield. Conclusion: The considered approach in the process validation of Tangential Flow Filtration system includes independent verification and application of parameters, which supports maximum yield of the vaccine product. The execution of these batches was successfully carried out in the laboratory that involves the purification of the upstream harvest sample for obtaining the maximum and consistent yield concentration of the drug substance with the decisive designing and validation of process parameters.

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Carvajal-Zarrabal, Octavio, Samantha Ling-Chee Siong, Mohammad Omar Abdullah, Yie Hua Tan, Esaki Shoji, Miguel Ángel Morales-Mora, Jesús Carrillo-Ahumada e Cirilo Nolasco-Hipolito. "Recovery of Membrane Permeability after Filtration of Sago Starch Suspension by Tangential Flow Filtration". Journal of Applied Research and Technology 21, n. 3 (27 giugno 2023): 384–96. http://dx.doi.org/10.22201/icat.24486736e.2023.21.3.1814.

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Sago starch is extracted from the stems of the sago palm, Metroxylon sagu, in south-east Asia. Sago starch processing generates approximately 20 tons of starch containing effluents that can be recovered and marketed to sustain a small-scale industry. Tangential flow filtration (TFF) using microfiltration membranes (MFM) has been demonstrated as an effective method for separating suspended solids in biological effluents. When TFF was applied to concentrate sago starch suspensions (SSS), membrane permeability and lifecycle were impacted due to frequent fouling. This study evaluated cleaning methods to recover the permeability and extend the lifecycle of MFM following TFF application. Polysulfone membrane filter cassettes of pore size 0.45 µm and surface area 0.1 m2 were each used to separate starch in 100 L of SSS. Following separation, six chemical and physical cleaning methods were tested at laboratory-scale and the degree of cleaning was measured by normalized permeate flux (NPF) and normalized water permeability (NWP). The results showed that soaking the membranes in a 0.2 M NaOH solution (up to 91%, (p<0.05) within the shortest time of 72 h, (p<0.05) was the best cleaning method. The procedure has been utilized to maintain and extend the lifecycle of the MFM for streams containing starch suspensions.

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Chan, See Yi, Kok Chung Chong, Woon Chan Chong, Soon Onn Lai, Yean Ling Pang e Shee Keat Mah. "Effect of Flowrate and Pressure on the Crossflow Filtration in Textile Wastewater Treatment by Commercial UF Membrane". IOP Conference Series: Earth and Environmental Science 1303, n. 1 (1 febbraio 2024): 012022. http://dx.doi.org/10.1088/1755-1315/1303/1/012022.

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Abstract Textile industries are one of the greatest wastewater producers as they require a significant amount of water to be used in the dyeing and finishing processes of textile manufacturing. The number of unit operations in the technological process, the product range, the bath ratio, the mass of fiber in relation to the bath volume, and the finishing machine are some variables that will affect water consumption in the textile industry. As a result, generally, a typical textile plant may consume a volume of water between 100,000 and 300,000 m3 annually. As textiles address a substantial portion of human requirements, it is predicted that by 2050, there will be 160 million metric tonnes, three times as much clothing as there is today. Membrane technology in wastewater treatment is a recent interest arising technique and garnering the industrial application’s interest, owing to its ease of setup and low energy requirement. Crossflow membrane filtration is commonly used in the industry, attributed to its tangential flow across the membrane mechanism, leading to low fouling. This study investigated the textile wastewater’s effluents using crossflow ultrafiltration (UF) membrane filtration. The effect of the operating parameter in terms of pressure and flowrate of the crossflow system were performed to evaluate it permeate flux performance. The study’s outcome reveals pressure increases from 2 bar to 4 bar, the water flux enhances dramatically from 156.26 L/m2hr to 591.98 L/m2hr, and the water flux further increases constantly from 4 bar to 10 bar. On the other hand, the flowrate positively affects the permeate flux, where the flux was enhanced from 651.01 L/m2hr to 726.08 L/m2hr when adjusting the flow rate from 2 LPM to 6 LPM. The results from this study suggested that crossflow membrane filtration system could be commercially feasible due to its permeate flux performance.

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Dziubak, Tadeusz. "Experimental Investigation of Possibilities to Improve Filtration Efficiency of Tangential Inlet Return Cyclones by Modification of Their Design". Energies 15, n. 11 (24 maggio 2022): 3871. http://dx.doi.org/10.3390/en15113871.

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It has been shown that tangential inlet return cyclones are commonly used for inlet air filtration of off-road vehicle engines. The wear of the engine elements, and thus their durability, is determined by the efficiency and accuracy of the inlet air filtration. It has been shown that the possibilities of increasing the separation efficiency or decreasing the pressure drop of a cyclone by changing the main dimensions of the cyclone are limited, because any arbitrary change in one of the dimensions of an already operating cyclone may cause the opposite effect. A literature analysis of the possibility of increasing the filtration efficiency of cyclones by modifying the design of selected cyclone components was conducted. In this paper, three modifications of the cyclone design with a tangential inlet of the inlet air filter of a military tracked vehicle were proposed and performed. The symmetrical inlet of the cyclone was replaced with an asymmetrical inlet. The cylindrical outlet tube was replaced with a conical tube, and the edges of the inlet opening were given an additional streamlined shape. The modification process was carried out on three specimens of the reversible cyclone with a tangential inlet. After each modification, an experimental evaluation of the modifications was carried out. The influence of the modifications on the cyclone’s efficiency characteristics and pressure drop was examined. Subsequent modifications of the cyclone were performed on the same specimen without removing the previous modifications. Tests were performed in the air flow range QG = 5–30 m3/h. Polydisperse “fine” test dust with grain size dpmax = 80 µm was used for testing. The dust concentration at the cyclone inlet was set at 1 g/m2. The performed modifications caused a slight (about 1%) increase in separation efficiency in the range of small (up to QG = 22 m3/h) flux values and about 30% decrease in pressure drop in the whole range of the QG flux, which positively influences the increase in engine filling and its power. There was a noticeable increase in filtration accuracy in the range of low and high values of QG flux, which results in a decrease in the wear of engine components, especially the piston-piston ring-cylinder (P-PR-C) association, and an increase in their durability.

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Sivaprakash, Prabhavathy, e Sunando DasGupta. "Effect of air sparging on flux enhancement during tangential flow filtration of degreasing effluent". Desalination and Water Treatment 53, n. 1 (19 settembre 2013): 73–83. http://dx.doi.org/10.1080/19443994.2013.839400.

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Arkhangelsky, Elizabeth, Aimira Bazarbayeva, Arailym Kamal, Jong Kim, Vassilis Inglezakis e Vitaly Gitis. "Tangential streaming potential, transmembrane flux, and chemical cleaning of ultrafiltration membranes". Separation and Purification Technology 258 (marzo 2021): 118045. http://dx.doi.org/10.1016/j.seppur.2020.118045.

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CHOI, H., K. ZHANG, D. DIONYSIOU, D. OERTHER e G. SORIAL. "Effect of permeate flux and tangential flow on membrane fouling for wastewater treatment". Separation and Purification Technology 45, n. 1 (settembre 2005): 68–78. http://dx.doi.org/10.1016/j.seppur.2005.02.010.

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Batrinescu, Gheorghe, Roxana-Elena Scutariu, Nicolae-Ionut Cristea, Ioana-Alexandra Ionescu e Gheorghe Nechifor. "The Clogging Effect in the Process of Protein Separation by Ultrafiltration". Materiale Plastice 57, n. 3 (30 settembre 2020): 224–37. http://dx.doi.org/10.37358/mp.20.3.5395.

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In this study, five ultrafiltration membranes (polysulfone, cellulose acetate and polyethe-rsulfone) were tested in the treatment of aqueous protein solutions similar to wastewater from fermentation industries. The experiments were made in tangential flow filtration. The permeate flux for the five membranes tested at the optimum pressure of 3 bar decreased due to the effect of clogging the pores by the macromolecular protein solutions. Cellulose acetate membranes showed the lowest permeate flux (Ac-Cel1=152.4 L/m2.h and Ac-Cel2=40.3 L/m2.h) which doesn�t recommend them for the ultrafiltration process of bovine serum albumin. When a polysulfone membrane was used in several cycles of protein-containing wastewater ultrafiltration, the permeate flow decreased progressively from one cycle to another due to the internal clogging of the membrane (501.6 L/m2.h up to 444.0 L/m2.h). Regarding the ultrafiltration of protein solutions with a suspended yeast content, the clogging was predominant on the membrane�s surface, which results in a decrease of the permeate flux by over 50%.

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Lima, Rosa Carmo Oliveira, H. L. Lira, G. A. Neves, M. C. Silva e K. B. França. "Use of Ceramic Membrane for Indigo Separation in Effluent from Textile Industry". Materials Science Forum 798-799 (giugno 2014): 537–41. http://dx.doi.org/10.4028/www.scientific.net/msf.798-799.537.

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The production of fabrics is one important sectors of the national economy, especially in jeans production. During dyeing step, in the production of jeans, it is generate a large amount of wastewater rich in indigo, a strong blue dye that when released directly into the environment is responsible for several environmental impacts. The aim of this work is to study the use of microfiltration ceramic membranes for indigo separation in effluents from textile industry. Initially the ceramic membranes were characterized in relation to the pore size and tangential flux. It was produced an indigo solution whose concentration and composition similar to the effluent of textile industry. The solution was characterized and submitted to a filtration through ceramic membranes by tangential flow, by applying a pressure of 3 Bar. At the end it was verified that 99% of the indigo was retained.

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Chaubal, Akshay S., e Andrew L. Zydney. "Single-Pass Tangential Flow Filtration (SPTFF) of Nanoparticles: Achieving Sustainable Operation with Dilute Colloidal Suspensions for Gene Therapy Applications". Membranes 13, n. 4 (15 aprile 2023): 433. http://dx.doi.org/10.3390/membranes13040433.

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Recent approval of several viral-vector-based therapeutics has led to renewed interest in the development of more efficient bioprocessing strategies for gene therapy products. Single-Pass Tangential Flow Filtration (SPTFF) can potentially provide inline concentration and final formulation of viral vectors with enhanced product quality due. In this study, SPTFF performance was evaluated using a suspension of 100 nm nanoparticles that mimics a typical lentivirus system. Data were obtained with flat-sheet cassettes having 300 kDa nominal molecular weight cutoff, either in full recirculation or single-pass mode. Flux-stepping experiments identified two critical fluxes, one based on boundary-layer particle accumulation (Jbl) and one based on membrane fouling (Jfoul). The critical fluxes were well-described using a modified concentration polarization model that captures the observed dependence on feed flow rate and feed concentration. Long-duration filtration experiments were conducted under stable SPTFF conditions, with the results suggesting that sustainable performance could potentially be achieved for as much as 6 weeks of continuous operation. These results provide important insights into the potential application of SPTFF for the concentration of viral vectors in the downstream processing of gene therapy agents.

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Walther, Jason, Jean McLarty e Timothy Johnson. "The effects of alternating tangential flow (ATF) residence time, hydrodynamic stress, and filtration flux on high‐density perfusion cell culture". Biotechnology and Bioengineering 116, n. 2 (dicembre 2018): 320–32. http://dx.doi.org/10.1002/bit.26811.

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Loewe, Daniel, Tanja A. Grein, Hauke Dieken, Tobias Weidner, Denise Salzig e Peter Czermak. "Tangential Flow Filtration for the Concentration of Oncolytic Measles Virus: The Influence of Filter Properties and the Cell Culture Medium". Membranes 9, n. 12 (29 novembre 2019): 160. http://dx.doi.org/10.3390/membranes9120160.

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The therapeutic use of oncolytic measles virus (MV) for cancer treatment requires >108 infectious MV particles per dose in a highly pure form. The concentration/purification of viruses is typically achieved by tangential flow filtration (TFF) but the efficiency of this process for the preparation of MV has not been tested in detail. We therefore investigated the influence of membrane material, feed composition, and pore size or molecular weight cut-off (MWCO) on the recovery of MV by TFF in concentration mode. We achieved the recovery of infectious MV particles using membranes with a MWCO ≤ 300 kDa regardless of the membrane material and whether or not serum was present in the feed. However, serum proteins in the medium affected membrane flux and promoted fouling. The severity of fouling was dependent on the membrane material, with the cellulose-based membrane showing the lowest susceptibility. We found that impurities such as proteins and host cell DNA were best depleted using membranes with a MWCO ≥ 300 kDa. We conclude that TFF in concentration mode is a robust unit operation to concentrate infectious MV particles while depleting impurities such as non-infectious MV particles, proteins, and host cell DNA.

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HALDENWANG, P. "Laminar flow in a two-dimensional plane channel with local pressure-dependent crossflow". Journal of Fluid Mechanics 593 (23 novembre 2007): 463–73. http://dx.doi.org/10.1017/s0022112007008622.

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Long ducts (or pipes) composed of transpiring (e.g. porous) walls are at the root of numerous industrial devices for species separation, as tangential filtration or membrane desalination. Similar configurations can also be involved in fluid supply systems, as irrigation or biological fluids in capillaries. A transverse leakage (or permeate flux), the strength of which is assumed to depend linearly on local pressure (as in Starling's law for capillary), takes place through permeable walls. All other dependences, as osmotic pressure or partial fouling due to polarization of species concentration, are neglected. To analyse this open problem we consider the simplest situation: the steady laminar flow in a two-dimensional channel composed of two symmetrical porous walls.First, dimensional analysis helps us to determine the relevant parameters. We then revisit the Berman problem that considers a uniform crossflow (i.e. pressure-independent leakage). We expand the solution in a series of Rt, the transverse Reynolds number. We note this series has a rapid convergence in the considered range of Rt (i.e. Rt ≤ O(1)). A particular method of variable separation then allows us to derive from the Navier–Stokes equations two new ordinary differential equations (ODE), which correspond to first and second orders in the development in Rt, whereas the zero order recovers the Regirer linear theory. Finally, both new ODEs are used to study the occurrence of two undesirable events in the filtration process: axial flow exhaustion (AFE) and crossflow reversal (CFR). This study is compared with a numerical approach.

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Mendes, Sónia, Tiago Q. Faria, André Nascimento, Marc Noverraz, Franziska Bollmann, Piergiuseppe Nestola, António Roldão, Cristina Peixoto e Ricardo J. S. Silva. "Accelerated Development of AAV Purification Process Using a High-Throughput and Automated Crossflow System". Separations 11, n. 3 (26 febbraio 2024): 73. http://dx.doi.org/10.3390/separations11030073.

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Adeno-associated viruses (AAV) are currently predominant viral transfer tools for gene therapy, and efforts are being made to design faster and more efficient methods and technologies for their manufacturing. The early selection of high-performing filters is essential for developing an ultrafiltration and diafiltration (UF/DF) process, especially when feed material is scarce, and timelines are short. However, few methods and technologies exist to enable process optimization with multiple variations in a single run. In this study, we explored the potential of Ambr® Crossflow for high-throughput, automated screening of different membrane materials, pore sizes and different process conditions for the UF/DF step of AAV8. The best overall performance was obtained with a 100 kDa PES flat sheet cassette. The UF/DF process was further transferred to a larger scale to the Sartoflow® Smart Tangential Flow Filtration (TFF) system using a 100 kDa PES Sartocon® Slice 200 cassette and compared to a 100 kDa PES hollow fiber. Virus recovery, permeate flux and total protein removal values of the flat sheet cassette were similar to those achieved in small-scale devices, and higher than those of the hollow fiber, thus demonstrating similar performance at a larger process scale. The high-throughput, automated method described herein allowed to screen multiple materials and process parameters of a UF/DF process in a time- and resource-efficient way, making it a useful tool to accelerate early-stage downstream process development of AAV.

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Diban, Nazely, Beatriz Gómez-Ruiz, María Lázaro-Díez, Jose Ramos-Vivas, Inmaculada Ortiz e Ane Urtiaga. "Factors Affecting Mass Transport Properties of Poly(ε-caprolactone) Membranes for Tissue Engineering Bioreactors". Membranes 8, n. 3 (1 agosto 2018): 51. http://dx.doi.org/10.3390/membranes8030051.

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High porosity and mass transport properties of microfiltration polymeric membranes benefit nutrients supply to cells when used as scaffolds in interstitial perfusion bioreactors for tissue engineering. High nutrients transport is assumed when pore size and porosity of the membrane are in the micrometric range. The present work demonstrates that the study of membrane fouling by proteins present in the culture medium, though not done usually, should be included in the routine testing of new polymer membranes for this intended application. Two poly(ε-caprolactone) microfiltration membranes presenting similar average pore size (approximately 0.7 µm) and porosity (>80%) but different external surface porosity and pore size have been selected as case studies. The present work demonstrates that a membrane with lower surface pore abundance and smaller external pore size (approximately 0.67 µm), combined with adequate hydrodynamics and tangential flow filtration mode is usually more convenient to guarantee high flux of nutrients. On the contrary, having large external pore size (approximately 1.70 µm) and surface porosity would incur important internal protein fouling that could not be prevented with the operation mode and hydrodynamics of the perfusion system. Additionally, the use of glycerol in the drying protocols of the membranes might cause plasticization and a consequent reduction of mass transport properties due to membrane compaction by the pressure exerted to force perfusion. Therefore, preferentially, drying protocols that omit the use of plasticizing agents are recommended.

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Pipich, Vitaliy, Thomas Starc, Johan Buitenhuis, Roni Kasher, Winfried Petry, Yoram Oren e Dietmar Schwahn. "Silica Fouling in Reverse Osmosis Systems–Operando Small-Angle Neutron Scattering Studies". Membranes 11, n. 6 (30 maggio 2021): 413. http://dx.doi.org/10.3390/membranes11060413.

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We present operando small-angle neutron scattering (SANS) experiments on silica fouling at two reverse osmose (RO) membranes under almost realistic conditions of practiced RO desalination technique. To its realization, two cells were designed for pressure fields and tangential feed cross-flows up to 50 bar and 36 L/h, one cell equipped with the membrane and the other one as an empty cell to measure the feed solution in parallel far from the membrane. We studied several aqueous silica dispersions combining the parameters of colloidal radius, volume fraction, and ionic strength. A relevant result is the observation of Bragg diffraction as part of the SANS scattering pattern, representing a crystalline cake layer of simple cubic lattice structure. Other relevant parameters are silica colloidal size and volume fraction far from and above the membrane, as well as the lattice parameter of the silica cake layer, its volume fraction, thickness, and porosity in comparison with the corresponding permeate flux. The experiments show that the formation of cake layer depends to a large extent on colloidal size, ionic strength and cross-flow. Cake layer formation proved to be a reversible process, which could be dissolved at larger cross-flow. Only in one case we observed an irreversible cake layer formation showing the characteristics of an unstable phase transition. We likewise observed enhanced silica concentration and/or cake formation above the membrane, giving indication of a first order liquid–solid phase transformation.

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Tom, Wesley A., James Wells, Kristin E. Hales e Samodha C. Fernando. "43 Characterization of the Fecal Virome in Beef Cattle with and Without Antibiotic Exposure". Journal of Animal Science 100, Supplement_2 (12 aprile 2022): 11–12. http://dx.doi.org/10.1093/jas/skac064.017.

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Abstract Mitigating the spread of antimicrobial resistance (AMR) has become a top priority globally over the last decade. Thus, understanding how bacterial communities acquire and transfer antibiotic resistance is of upmost importance in identifying intervention points for maintaining antibiotic efficacy. It is well documented that horizontal gene transfer (HGT) via bacteriophage transduction has the potential to shift metabolic flux in bacterial communities, yet phage mediated HGT in feedlot cattle with regard to AMR remains poorly characterized. Here we characterize the viral community of 72 beef cattle, where 36 animals received antibiotic exposure and 36 control animals received no antibiotic exposure throughout the duration of the study. Treatment groups were divided into 9 pens with 4 animals per pen. Fecal samples were collected at 3 timepoints and pooled by pen for viral enrichments. Viral particle enrichment was performed using tangential flow filtration and ultracentrifugation. Viral DNA/RNA was extracted with Zymo Quick-DNA/RNA Viral Magbead extraction kit, and shotgun metagenomic libraries were prepared using NEBNext Ultra II library prep kit for Illumina. Libraries were sequenced on the Illumina HiSeq platform (150bp paired-end reads). Sequencing reads were assembled using MEGAHIT, viral genomes were predicted using Virsorter2 and CheckV, and annotated using VIBRANT. In total, 5,875 viral genomes were predicted from the dataset. 635 of those viral genomes were > 60% complete, and 45 were complete circular genomes. 544 auxiliary metabolic genes (AMGs) were detected across all genomes, spanning 49 metabolic pathways with most genes falling under energy, amino acid, and vitamin/cofactor metabolism. Notably, 25 genes involved in secondary metabolite biosynthesis of vancomycin, validamycin, streptomycin, and monobactams were detected. Results indicate that fecal bacteriophages harbor a wide array of AMGs with diverse metabolic potential, including secondary metabolites potentially involved with AMR. The USDA is an equal opportunity provider and employer.

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Trouvé, E., J. L. Maubois, M. Piot, M. N. Madec, J. Fauquant, A. Rouault, J. Tabard e G. Brinkman. "Rétention de différentes espèces microbiennes lors de l'épuration du lait par microfiltration en flux tangentiel". Le Lait 71, n. 1 (1991): 1–13. http://dx.doi.org/10.1051/lait:199111.

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23

Wang, Qian, Xiaobin Tang, Heng Liang, Wenjun Cheng, Guibai Li, Qingjun Zhang, Jie Chen, Kang Chen e Jinlong Wang. "Effects of Filtration Mode on the Performance of Gravity-Driven Membrane (GDM) Filtration: Cross-Flow Filtration and Dead-End Filtration". Water 14, n. 2 (11 gennaio 2022): 190. http://dx.doi.org/10.3390/w14020190.

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Abstract (sommario):

Gravity-driven membrane (GDM) filtration technology has been extensively in the employed drinking water treatment, however, the effect filtration mode (i.e., dead-end mode vs. cross-flow mode) on its long-term performance has not been systematically investigated. In this study, pilot-scale GDM systems were operated using two submerged filtration mode (SGDM) and cross-flow mode (CGDM) at the gravity-driven pressures 120 mbar and 200 mbar, respectively. The results showed that flux stabilization was observed both in the SGDM and CGDM during long-term filtration, and importantly the stabilized flux level of CGDM was elevated by 3.5–67.5%, which indicated that the filtration mode would not influence the occurrence of flux stability, but significantly improve the stable flux level. Interestingly, the stable flux level was not significantly improved with the increase of driven pressure, and the optimized driven pressure was 120 mbar. In addition, the GDM process conferred effective removals of turbidity, UV254, CODMn, and DOC, with average removals of 99%, 43%, 41%, and 20%, respectively. With the assistance of cross flow to avert the overaccumulation of contaminants on the membrane surface, CGDM process exhibited even higher removal efficiency than SGDM process. Furthermore, it can be found that the CGDM system can effectively remove the fluorescent protein-like substances, and the intensities of tryptophans substance and soluble microbial products were reduced by 64.61% and 55.08%, respectively, higher than that of the SGDM. Therefore, it can be determined that the filtration mode played an important role in the flux stabilization of GDM system during long-term filtration, and the cross-flow filtration mode can simultaneously improve the stabilized flux level and removal performance.

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24

Kim, J. P., J. J. Kim, M. S. Chun, B. R. Min e K. Y. Chung. "Flux enhancement by glass balls inserted membrane module". Water Supply 1, n. 5-6 (1 giugno 2001): 285–92. http://dx.doi.org/10.2166/ws.2001.0125.

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Abstract (sommario):

The glass ball inserted membrane module presented in this study is designed to enhance filtration in a flat sheet membrane. Three different modes of filtration experiments were conducted and compared to demonstrate flux enhancement due to the presence of glass balls: a normal dead-end filtration, a vortex flow filtration, and an enhanced vortex flow filtration using glass balls. In the case of enhanced vortex flow filtration the permeate flux was found to be three times as large as that of the dead-end filtration, and two times larger compared with the vortex flow filtration. In addition, the flux decline was observed to be relatively low. The effect of the amount of glass balls on the permeate flux was also investigated by changing the values of glass ball volume fraction from 0.059 to 0.356. It has been observed that the permeate flux shows a maximum value of the volume fraction of 0.119. For the glass ball inserted membrane module, the permeate flux tends to increase with the feed flow rate.

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25

Baker, R. J., A. G. Fane, C. J. D. Fell e B. H. Yoo. "Factors affecting flux in crossflow filtration". Desalination 53, n. 1-3 (gennaio 1985): 81–93. http://dx.doi.org/10.1016/0011-9164(85)85053-0.

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26

Hwang, E. J., D. D. Sun e J. H. Tay. "Operational factors of submerged inorganic membrane bioreactor for organic wastewater treatment: sludge concentration and aeration rate". Water Science and Technology 47, n. 1 (1 gennaio 2003): 121–26. http://dx.doi.org/10.2166/wst.2003.0032.

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Abstract (sommario):

Various sludge concentrations and aeration rates were evaluated to find the optimal operation condition of a submerged ceramic membrane filtration system. 5.6 g/L of sludge was diluted with water to concentrations of 2.8 g/L and 1.4 g/L, and the three sludge concentrations were compared in terms of filtration characteristics such as pressure and filtrate flux. Flux was at the highest value of about 30 L/m2.hr at 50 kPa when sludge concentration was 1.4 g/L. In contrast, when sludge concentrations increased to 2.8 g/L and 5.6 g/L, the flux at 50 kPa decreased significantly to 18 L/m2.hr and 10 L/m2.hr, respectively. It was concluded that the sludge concentration directly affected the filtration efficiency, and low sludge concentration was suitable for improving filtration efficiency. Adjusting the aeration rate from 2 L/min to 4 L/min at 5.6 g/L of sludge and 50 kPa of pressure increased flux from 10 L/m2.hr to 13 L/m2.hr. It was obvious that the vigorous aeration improved the filtration efficiency, but the aeration rate did not seem to be high enough to maintain flux lower than critical flux.

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27

Xu, Yilu, James Russell, Gahtan S. M. Algahtani e Darren L. Oatley-Radcliffe. "Valorising Nutrient-Rich Digestate as a Waste-Based Media for Microalgal Cultivation: Bench-Scale Filtration Characterisation and Scale-Up for a Commercial Recovery Process". Energies 15, n. 16 (18 agosto 2022): 5976. http://dx.doi.org/10.3390/en15165976.

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Abstract (sommario):

Cultivating microalgae requires a nitrogen and phosphorous feed source. Anaerobic digestion waste (digestate) provides a cheap sustainable feedstock for these materials. Previous studies have successfully demonstrated the feasibility of nutrient recovery and subsequent algae growth. There is now a need to fully characterise digestate filtration to improve our understanding of this process prior to its commercialisation. In this work, digestate filtration is characterised at bench scale using frontal (dead-end) filtration and a 100 kDa MWCO ultrafiltration membrane. Our experiments demonstrated rapid cake formation causing significant flux decline. The steady-state permeate flux for digestate was 2.4 to 4.8 L m−2 h−1, a reduction of ~90% compared to clean water flux. The specific cake resistance was ~1015 m kg−1 and the compressibility index 1.07. A series of four filtration and cleaning cycles showed 90% flux recovery following a clean water wash. Digestate filtration was then evaluated at a commercial scale using crossflow and the KOCH ABCOR® tubular membrane (100 kDa MWCO). The results were similar to those at the bench scale, i.e., rapid initial fouling leading to a period of steady-state flux (approximately 7 L m−2 h−1). The commercial membrane was flushed with water and diluted bleach after each use, and a digestate permeate flux decline of only 4.8% over a 12-month active use period was observed. The present research provides bench scale characterisation and demonstrates the commercial scale operation of anaerobic digestate filtration using ultrafiltration. The overall filtration performance was excellent, and the process can now be scaled to any operational capacity.

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28

Chuanwen, Sun, Wang Haiqiao, Yu Qi, Chen Shiqiang, Li Xun e Wu Hanyang. "Experimental study of the flux Law of flat ceramic membranes under different pressures". Water Practice and Technology 15, n. 2 (10 aprile 2020): 416–25. http://dx.doi.org/10.2166/wpt.2020.028.

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Abstract (sommario):

Abstract The flux performance of ceramic membranes is the basis for their efficient use. To study ceramic membrane flux variation, different filtration operating conditions were tested and the functional relationship between the membrane's clean water flux and the operating pressure within a given range obtained. The membrane's critical pressure and flux were determined by using pressure increments, and the flux variation law under different pressures determined experimentally. Analysis of the flux law and the membrane parameters enabled establishment of the flux model of filtration process and a model of flux stabilization after the deposition layer formed. The applicability of the model was proved by comparing and verifying the experimental data.

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Laabs, C., G. Amy e M. Jekel. "Organic colloids and their influence on low-pressure membrane filtration". Water Science and Technology 50, n. 12 (1 dicembre 2004): 311–16. http://dx.doi.org/10.2166/wst.2004.0728.

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Abstract (sommario):

Wastewater treatment by low-pressure membrane filtration (MF and UF) is affected to a large extent by macromolecules and colloids. In order to investigate the influence of organic colloids on the membrane filtration process, colloids were isolated from a wastewater treatment plant effluent using a rotaryevaporation pre-concentration step followed by dialysis. Stirred cell tests were carried out using redissolved colloids, with and without additional glass fiber filtration. After constant pressure membrane filtration of 190 L/m2, the initial flux had declined by 50% for colloids > 6-8 kD (glass fiber filtered) with a hydrophilic MF membrane and for colloids >12-14 kD (glass fiber filtered) with a hydrophobic MF membrane. For the non-filtered colloidal solutions, the flux decline was even steeper with the flux being below 10% of the initial flux after 190 L/m2 were passed through the membranes. As with larger particles, colloids form a filtration cake layer on top of the membrane surface when used as isolates without prior filtration. This filtration cake is easily removed during backwashing. However, polysaccharides as a macromolecular component of the colloid isolate cause severe fouling by the formation of a gel layer on the membrane surface that is difficult to remove completely.

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30

Hashino, M., Y. Mori, Y. Fujii, K. Nakatani, H. Hori, K. Takahashi, N. Motoyama, K. Mizuno e T. Minegishi. "Advanced water treatment system using ozone and ozone resistant microfiltration module". Water Supply 1, n. 5-6 (1 giugno 2001): 169–75. http://dx.doi.org/10.2166/ws.2001.0111.

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Abstract (sommario):

In order to achieve an efficient and economical advanced drinking water system, the relationship between operating conditions, membrane filtration flux and water qualities was examined by using a pilot plant consisting of ozonation facility, ozone resistant microfiltration (MF) module and granular activated carbon (GAC) tower. It was found that keeping residual ozone of more than 0.3 mg/L on the membrane surface is necessary in order to obtain a high membrane filtration flux. Withy ozone dosage of 3 mg/L by ejector and filtration by dead-end mode, this new system provided a high membrane filtration flux of more than 5 m3/m2/day. Quality of the produced water from the GAC tower was meeting the drinking water standard.

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31

Azam, Reem S., Dema A. Almasri, Radwan Alfahel, Alaa H. Hawari, Mohammad K. Hassan, Ahmed A. Elzatahry e Khaled A. Mahmoud. "MXene (Ti3C2Tx)/Cellulose Acetate Mixed-Matrix Membrane Enhances Fouling Resistance and Rejection in the Crossflow Filtration Process". Membranes 12, n. 4 (6 aprile 2022): 406. http://dx.doi.org/10.3390/membranes12040406.

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Abstract (sommario):

Obstacles in the membrane-based separation field are mainly related to membrane fouling. This study involved the synthesis and utilization of covalently crosslinked MXene/cellulose acetate mixed matrix membranes with MXene at different concentrations (CCAM-0% to CCAM-12%) for water purification applications. The membranes’ water flux, dye, and protein rejection performances were compared using dead-end (DE) and crossflow (CF) filtration. The fabricated membranes, especially CCAM-10%, exhibited high hydrophilicity, good surface roughness, significantly high water flux, high water uptake, and high porosity. A significantly higher flux was observed in CF filtration relative to DE filtration. Moreover, in CF filtration, the CCAM-10% membrane exhibited 96.60% and 99.49% rejection of methyl green (MG) and bovine serum albumin (BSA), respectively, while maintaining a flux recovery ratio of 67.30% and an irreversible fouling ratio at (Rir) of 32.70, indicating good antifouling performance. Hence, this study suggests that covalent modification of cellulose acetate membranes with MXene significantly improves the performance and fouling resistance of membranes for water filtration in CF mode relative to DE mode.

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32

Ayu Mauliasyam, Tsaniyah, Slamet Budijanto e Azis Boing Sitanggang. "Maillard reaction products between whey powder and water-soluble tempeh protein extract: membrane-based fractionation". Annals of the University Dunarea de Jos of Galati. Fascicle VI - Food Technology 47, n. 1 (20 marzo 2023): 64–78. http://dx.doi.org/10.35219/foodtechnology.2023.1.04.

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Abstract (sommario):

Whey powder, an industrial by-product, has the potential to be transformed into functional ingredients using the Maillard reaction. In this study, this chemical reaction occurred between whey powder and tempeh protein extract, resulting in increased antioxidant activity. This study aimed to isolate the Maillard reaction products (MRP) with the best antioxidant capacity using an ultrafiltration (UF) membrane by considering the fouling phenomenon that occurred on the membrane surface and critical flux for the filtration. MRP exhibited an antioxidant capacity of 0.09 mg ascorbic acid equivalent antioxidant capacity/mL, and the fractionation using a 5 kDa MWCO PES membrane showed the highest antioxidant capacity in terms of free radical reduction and metal chelating mechanisms. During MRP filtration, fouling on the membrane surface was observed, which could be attributed to the cake filtration model. The critical flux value was determined to be 4.23 LMH with a corresponding pressure of 0.75 bar. A long-term filtration below the critical flux showed stable performance, but filtration above the critical flux resulted in significant fouling. The permeate antioxidant IC50 value was 4.25 mg/mL. Based on the LC-MS analysis, 1,4-dihydroxy-2-methyl-anthraquinone and ilexin II were found as the potential contributors to the antioxidant activity of MRP. In summary, our study demonstrates that fractionating MRP using UF membrane-based filtration is an effective method for isolating MRP with high antioxidant capacity. Our findings also shed light on the critical flux value and fouling phenomenon during MRP filtration, which are important considerations for scaling up the production process.

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33

Chen, Yan, Zi Wen Xiao e Guo Zhen Zhang. "The Effect of Coagulation on Preventing UF Membrane from Fouling". Advanced Materials Research 113-116 (giugno 2010): 1353–57. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.1353.

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Abstract (sommario):

In this experiment, the effects on improve of flux and prevention of membrane from fouling was studied. The results demonstrated that after backwashing, the flux was completely recovered by addition of 4mg/L and 10mg/L（as Al）, while the flux was only 40% of initial flux without coagulation pretreatment. It was also found that whether or not prevention of fouling by coagulation was depended on the characteristics of cake layer formed on membrane surface during membrane filtration. In the presence of filtration of coagulation floc suspension, coagulation could form cake layer on membrane surface, thus prevent membrane from fouling effectively, while in the presence of filtration of supernatant, fouling was occurred due to cake layer comprising small, neutral, hydrophilic compounds, which can not removed by backwash.

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34

Jo, Kyungkeun. "The Change of Forward Osmosis Filtration Performance by Trace Organic Compounds in Heavy Metal Removal by Forward Osmosis Filtration". Journal of Korean Society of Environmental Engineers 43, n. 3 (31 marzo 2021): 187–95. http://dx.doi.org/10.4491/ksee.2021.43.3.187.

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Abstract (sommario):

Objectives : The purpose of this study was to examine how the presence of trace organic compounds (TROCs) affects water flux and heavy metal rejection in forward osmosis (FO) filtration when feed solution (FS) contains TROCs and heavy metals.Methods : Four FS (① only heavy metals, ② heavy metals and Trimethoprim, ③ heavy metals and Ibuprofen, ④ heavy metals and Triclosan) were used, and the FO filtration experiments were conducted to perform comparative analysis on the water flux and the rejection rate depending on the FS type.Results and Discussion : The water flux was higher when FS contained TROCs except Ibuprofen, compared to FS containing only heavy metals. It is speculated that the increased water flux was influenced by the decrease in the internal concentration polarization (ICP), which was caused by the adsorption of the TROCs in the support layer of the membrane. The water flux decreased when FS contained Ibuprofen, and this may be because reverse salt flux increased due to the Gibbs-Donnan effect. The rejection rate was not affected by TROCs when heavy metals were mostly rejected in FO filtration, but for the heavy metal that was not fully rejected, the rejection rate increased when FS contained TROCs. It is speculated that this was mainly due to clogging caused by the adsorption on the membrane.Conclusions : It was demonstrated that the presence of TROCs in FS can affect water flux and the rejection rate of heavy metals. Therefore, when the FS containing heavy metals and various organic substances is treated by FO filtration, the performance of the filtration is expected to change depending on the composition of the solution.

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35

Chahine, G. L., K. M. Kalumuck, Patrick D. Aley e G. S. Frederick. "High Flux Rate Particle Filtration From Liquids". Journal of Fluids Engineering 121, n. 1 (1999): 163. http://dx.doi.org/10.1115/1.2821997.

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36

Viñas, Adolfo F., e Alexander J. Klimas. "Flux-balance Vlasov simulation with filamentation filtration". Journal of Computational Physics 375 (dicembre 2018): 983–1004. http://dx.doi.org/10.1016/j.jcp.2018.09.014.

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37

Grenier, Alexia, Martine Meireles, Pierre Aimar e Philippe Carvin. "Analysing flux decline in dead-end filtration". Chemical Engineering Research and Design 86, n. 11 (novembre 2008): 1281–93. http://dx.doi.org/10.1016/j.cherd.2008.06.005.

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38

Chu, Huaqiang, Bingzhi Dong, Yalei Zhang e Xuefei Zhou. "Gravity filtration performances of the bio-diatomite dynamic membrane reactor for slightly polluted surface water purification". Water Science and Technology 66, n. 5 (1 settembre 2012): 1139–46. http://dx.doi.org/10.2166/wst.2012.284.

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Abstract (sommario):

A bio-diatomite dynamic membrane (BDDM) reactor for surface water treatment under a water head of 30, 40, 50, 60 and 70 cm, respectively, was investigated, which was very effective for pollutants removal. The water head exerted strong influences on filtration flux of BDDM during the precoating process, as well as on the formation of BDDM and turbidity variations. A high filtration flux (approximately 200−300 L/m2 h) could be achieved in the long filtration times of BDDM with a stable effluent turbidity of approximately 0.11−0.25 NTU. The BDDM could remove particles larger than 25 μm completely. The adopted sintered diatomite mainly consisted of macro pores, which were beneficial for improving the filtration flux of BDDM. During the backwash stage, the BDDM could be removed completely by the air backwash.

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39

Kennedy, M., S. Siriphannon, S. van Hoof e J. Schippers. "Improving the performance of dead-end ultrafiltration systems: comparing air and water flushing". Water Supply 1, n. 5-6 (1 giugno 2001): 97–106. http://dx.doi.org/10.2166/ws.2001.0104.

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Abstract (sommario):

A cleaning protocol that effectively removes fouling from hollow fiber UF systems without excessive use of chemicals, product water or (long) down time is needed. Cross flushing with UF feed water has been reported to increase the net flux of hollow fiber systems by reducing the frequency of backwashing, the consumption of permeate and the system down time. In this study, the flux restoration achieved in a vertical and horizontal UF system employing an intermittent water and water/air cross flush were compared. The flux restoration in the vertical UF system was not improved by the addition of air to the water flush and a maximum flux restoration of 82% was achieved, irrespective of the presence of air. Similarly, in a horizontal ultrafiltration system, a maximum flux restoration of 82% was also achieved with a water flush (v = 1.63 m/s). However, the addition of air to the water flush decreased the flux restoration to 40% at the highest water/air ratio (33% air). Low flux restoration in the horizontal system was attributed to residual air in the module after cross flushing. Flushing with water alone (v = 1.63 m/s) yielded a wall shear stress of 16 Pa compared with 130 Pa and 279 Pa in the liquid film surrounding the air slugs in the horizontal and vertical UF system, respectively, with a water/air ratio of 2:1. Despite the high shear force on the cake layer accumulated when air was added to the system, the maximum flux restoration was 82% both with and without air. This was attributed to the fact that it was the filtration mechanism and not the shear force on the cake layer that limited flux restoration during cross flushing. To improve the flux restoration that can be achieved by the cross flushing process, the filtration mechanism must be manipulated to minimize blocking filtration and induce cake filtration from the beginning of each filtration cycle.

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40

Kiat, W. Y., K. Yamamoto e S. Ohgaki. "Optimal Fiber Spacing in Externally Pressurized Hollow Fiber Module for Solid Liquid Separation". Water Science and Technology 26, n. 5-6 (1 settembre 1992): 1245–54. http://dx.doi.org/10.2166/wst.1992.0567.

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Abstract (sommario):

Flux decline and clogging mechanism in hollow fiber bundle by activated sludge and kaolin clay suspensions were investigated experimentally. Filtration characteristics of hollow fiber bundles consisting of 10 fiber threads but different in packing density were observed. The main reason for severe flux decline was due to the accumulation of particles at the space in between fibers. The results showed that there was no particle accumulation when fiber packing density β was lower than a critical value βa. Maximum filtration flux and maximum membrane productivity Q/Vr,which is defined as the filtration rate per unit volume of bundle, were obtained below and at this point, respectively. When fiber packing density β was increased, accumulation of particles happened and flux declined rapidly to a minimum, then increased to a maximum and then decreased when surface clogging predominated in the case of activated sludge filtration, but remained almost constant for the case of kaolin clay suspensions. The critical point where accumulation of particles started was related to cross flow velocity. The higher the cross flow velocity, the higher the value of βa obtained.

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41

Jiang, T., M. D. Kennedy, B. F. Guinzbourg, P. A. Vanrolleghem e J. C. Schippers. "Optimising the operation of a MBR pilot plant by quantitative analysis of the membrane fouling mechanism". Water Science and Technology 51, n. 6-7 (1 marzo 2005): 19–25. http://dx.doi.org/10.2166/wst.2005.0617.

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Abstract (sommario):

In order to optimize some operational conditions of MBR systems, a MBR pilot plant equipped with a submerged hollow fibre membrane module was employed in this study. The pilot MBR was fed with real municipal wastewater and the filtration flux, backwashing interval, aeration frequency and temperature were varied. A filtration flux below 25 l/m2h is generally recommended, at below this flux, the MBR operated at sub-critical flux conditions, the filter cake was minimized and membrane fouling was mainly attributed to the membrane pore blocking. Moreover, the membrane fouling, at below 25 l/m2h, was more reversible to backwashing; above this value, backwashing became less efficient to clean the membrane. Less frequent backwashing (e.g. 600 s filtration/45 s backwashing) decreased the amount of fouling irreversible to backwashing and its performance was superior to that of frequent backwashing (e.g. 200 s filtration/15 s backwashing). The MBR suffered more fouling at low temperature conditions (e.g. at 13–14 °C) than at high temperature conditions (e.g. at 17–18 °C). A conceptual model was built up and successfully interpreted this temperature effect.

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42

Manzoor, Saher, Faheem Qasim, Muhammad Waseem Ashraf, Shahzadi Tayyaba, Nimra Tariq, Agustín L. Herrera-May e Enrique Delgado-Alvarado. "Simulation and Analysis of Anodized Aluminum Oxide Membrane Degradation". Sensors 23, n. 24 (13 dicembre 2023): 9792. http://dx.doi.org/10.3390/s23249792.

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Abstract (sommario):

Microelectromechanical systems (MEMS)-based filter with microchannels enables the removal of various microorganisms, including viruses and bacteria, from fluids. Membranes with porous channels can be used as filtration interfaces in MEMS hemofilters or mini-dialyzers. The main problems associated with the filtration process are optimization of membrane geometry and fouling. A nanoporous aluminum oxide membrane was fabricated using an optimized two-step anodization process. Computational strength modeling and analysis of the membrane with specified parameters were performed using the ANSYS structural module. A fuzzy simulation was performed for the numerical analysis of flux through the membrane. The membrane was then incorporated with the prototype for successive filtration. The fluid flux and permeation analysis of the filtration process have been studied. Scanning electron microscope (SEM) micrographs of membranes have been obtained before and after the filtration cycles. The SEM results indicate membrane fouling after multiple cycles, and thus the flux is affected. This type of fabricated membrane and setup are suitable for the separation and purification of various fluids. However, after several filtration cycles, the membrane was degraded. It requires a prolonged chemical cleaning. High-density water has been used for filtration purposes, so this MEMS-based filter can also be used as a mini-dialyzer and hemofilter in various applications for filtration. Such a demonstration also opens up a new strategy for maximizing filtration efficiency and reducing energy costs for the filtration process by using a layered membrane setup.

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43

Fekete, Laura, Ákos Ferenc Fazekas, Cecilia Hodúr, Zsuzsanna László, Áron Ágoston, László Janovák, Tamás Gyulavári, Zsolt Pap, Klara Hernadi e Gábor Veréb. "Outstanding Separation Performance of Oil-in-Water Emulsions with TiO2/CNT Nanocomposite-Modified PVDF Membranes". Membranes 13, n. 2 (8 febbraio 2023): 209. http://dx.doi.org/10.3390/membranes13020209.

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Abstract (sommario):

Membrane filtration is an effective technique for separating micro- and nano-sized oil droplets from harmful oil-contaminated waters produced by numerous industrial activities. However, significant flux reduction discourages the extensive application of this technology; therefore, developing antifouling membranes is necessary. For this purpose, various titanium dioxide/carbon nanotube (TiO2/CNT) nanocomposites (containing 1, 2, and 5 wt.% multi-walled CNTs) were used for the modification of polyvinylidene fluoride (PVDF) ultrafilter (250 kDa) membrane surfaces. The effects of surface modifications were compared in relation to the flux, the filtration resistance, the flux recovery ratio, and the purification efficiency. TiO2/CNT2% composite modification reduced both irreversible and total filtration resistances the most during the filtration of 100 ppm oil emulsions. The fluxes were approximately 4–7 times higher compared to the unmodified PVDF membrane, depending on the used transmembrane pressure (510, 900, and 1340 L/m2h fluxes were measured at 0.1, 0.2, and 0.3 MPa pressures, respectively). Moreover, the flux recovery ratio (up to 68%) and the purification efficiency (95.1–99.8%) were also significantly higher because of the surface modification, and the beneficial effects were more dominant at higher transmembrane pressures. TiO2/CNT2% nanocomposites are promising to be applied to modify membranes used for oil–water separation and achieve outstanding flux, cleanability, and purification efficiency.

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44

Park, Min-Ju, e Gyu-Tae Seo. "A Study on Membrane Filtration Characteristics of Methanogenic Mixed Liquor in Two Phase Anaerobic Digestion of Food Waste". Journal of Korean Society of Environmental Engineers 42, n. 3 (31 marzo 2020): 151–63. http://dx.doi.org/10.4491/ksee.2020.42.3.151.

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Abstract (sommario):

Objectives:An experimental study was conducted to investigate the membrane filtration characteristics of mixed liquor in methanogenic reactor to extend solid retention time (SRT) in food waste anaerobic digestion system.Methods:On the basis of the particle size distribution (0.5~700 µm) of the methanogenic mixed liquor, three grade membranes (MF, UF, NF) were tested in a stirred cell filtration and a plate type module. Furthermore foulants of membrane, especially UF, was investigated by SEM-EDS, FTIR, SEC.Results and Discussion:As a result UF membrane was selected for stable filtration of the liquor in terms of flux (2.51 L/m2･h･bar) and the flux recovery (100%) as well as filtration resistance (Total 7.15.E+13 m-1). Average flux was 18 L/m2･h･bar for the selected UF membrane in cross flow filtration using a flat plate module. The filtration results showed that membrane fouling was caused by gel and cake layer formed on the membrane surface and 90% of the initial flux could be recovered by physical washing. It was identified that major fouling causing materials were byproducts of carbohydrate and protein decomposition, and small amount of inorganic substance detected on the membrane surface were salt and struvite like materials.Conclusions:Based on the membrane filtration characteristics analyzed from the study, the UF membrane coupled anaerobic digestion is feasible to be applied as a novel food waste treatment system for SRT extension of the methanogenic reactor.

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45

Nguyen, S. T., F. A. Roddick e J. L. Harris. "Membrane foulants and fouling mechanisms in microfiltration and ultrafiltration of an activated sludge effluent". Water Science and Technology 62, n. 9 (1 novembre 2010): 1975–83. http://dx.doi.org/10.2166/wst.2010.505.

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Abstract (sommario):

Membrane fouling in microfiltration (MF) and ultrafiltration (UF) of an activated sludge (AS) effluent was investigated. It was found that the major membrane foulants were polysaccharides, proteins, polysaccharide-like and protein-like materials and humic substances. MF fouling by the raw effluent was governed by pore adsorption of particles smaller than the pores during the first 30 minutes of filtration and then followed the cake filtration model. UF fouling could be described by the cake filtration model throughout the course of filtration. Coagulation with alum and (poly)aluminium chlorohydrate (ACH) altered the MF fouling mechanism to follow the cake filtration model from the beginning of filtration. The MF and UF flux improvement by coagulation was due to the removal of some of the foulants in the raw AS effluent by the coagulants. The MF flux improvement was greater for alum than for ACH whereas the two coagulants performed equally well in UF. Coagulation also reduced hydraulically irreversible fouling on the membranes and this effect was more prominent in MF than in UF. The unified membrane fouling index (UMFI) was used to quantitatively evaluate the effectiveness of coagulation on membrane flux enhancement.

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46

Choiriyah, Dyah, Esfi Riandini e Arinta Wulandari. "PREPARATION MICRO-FILTRATION CERAMIC MEMBRANE FROM NATURAL ZEOLITE FOR PROCION RED MX8B AND METHYLENE BLUE FILTRATION". ALCHEMY Jurnal Penelitian Kimia 11, n. 1 (27 settembre 2016): 8. http://dx.doi.org/10.20961/alchemy.11.1.100.8-14.

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Abstract (sommario):

The study of ceramic membrane fabrication from natural zeolite and its utilization for filtration of procion red MX8B and methylene blue has been investigated. The purposes of this study are to determine the effect of pressure on membrane permeability and selectivity and utilize natural zeolite as ceramic membranes procion red MX8B and methylene blue filtration. The membrane was prepared by metide press pellets and then calcined at 850 oC. The membranes were characterized by mechanical test, flux and rejection of dye. The compression test of the membrane found the values of 1369.178 psi in dry conditions to 1388.933 psi in wet conditions. The flux test found that the higher the pressure applied, the flux was increase. However, the high pressure also decreased the selectivity. Rejection test found that the rejection of methylene blue filtration up to 70 %. Meanwhile, procion red MX8B filtration has rejectivity less than 20 %.

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47

Choiriyah, Dyah, Esfi Riandini e Arinta Wulandari. "PREPARATION MICRO-FILTRATION CERAMIC MEMBRANE FROM NATURAL ZEOLITE FOR PROCION RED MX8B AND METHYLENE BLUE FILTRATION". ALCHEMY Jurnal Penelitian Kimia 11, n. 1 (9 dicembre 2015): 8. http://dx.doi.org/10.20961/alchemy.v11i1.100.

Testo completo

Abstract (sommario):

The study of ceramic membrane fabrication from natural zeolite and its utilization for filtration of procion red MX8B and methylene blue has been investigated. The purposes of this study are to determine the effect of pressure on membrane permeability and selectivity and utilize natural zeolite as ceramic membranes procion red MX8B and methylene blue filtration. The membrane was prepared by metide press pellets and then calcined at 850 oC. The membranes were characterized by mechanical test, flux and rejection of dye. The compression test of the membrane found the values of 1369.178 psi in dry conditions to 1388.933 psi in wet conditions. The flux test found that the higher the pressure applied, the flux was increase. However, the high pressure also decreased the selectivity. Rejection test found that the rejection of methylene blue filtration up to 70 %. Meanwhile, procion red MX8B filtration has rejectivity less than 20 %.

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48

Oh, Hyun-je, June-Seok Choi, Byong-Bo Choi, Sangho Lee e Tae-Mun Hwang. "Effect of axial variation of flux on filtration characteristics of hollow fiber membrane for drinking water treatment". Water Supply 7, n. 4 (1 dicembre 2007): 95–101. http://dx.doi.org/10.2166/ws.2007.137.

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Abstract (sommario):

Understanding the fouling phenomena in submerged membrane systems is challenging because the efficiency of hollow fiber membrane highly depends on the dimensions of the fibers as well as filtration conditions. Thus, modeling filtration behavior of hollow fibers is important for improving the performance of hollow fiber system. In this work, a theoretical model based on critical flux concept was developed to simulate filtration resistance and axial pressure drop along the fiber in drinking water treatment. The application of a model for experimental data indicated that the model matches the experiments quite well. Thus, simulation of membrane system was carried out under various conditions using the parameters from the model fit. The axial distribution of pressure and flux affect the filtration characteristics of hollow fiber membranes. The effect of model parameters (specific cake resistance and critical flux) and module geometry were theoretically also investigated using the model.

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49

Zhao, Yujie, Xiaowei Liu, Meng Qi, Tian Bai, Kongyin Zhao e Xinxin Zhang. "Removal of Dyes and Cd2+ in Water by Kaolin/Calcium Alginate Filtration Membrane". Coatings 9, n. 4 (28 marzo 2019): 218. http://dx.doi.org/10.3390/coatings9040218.

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Kaolin/calcium alginate (kaolin/CaAlg) free-standing membranes were prepared by adding different amounts of Kaolin into the sodium alginate (NaAlg) casting solution and crosslinked by Ca2+ using urea as porogen agent. The morphology of the kaolin/CaAlg filtration membrane was characterized by scanning electron microscope (SEM). Then the kaolin/CaAlg membrane was used for the removal of dyes and Cd2+. The kaolin significantly improved the mechanical behavior and flux of the kaolin/CaAlg membrane. The flux reached 17.53 L/m2·h at 0.1 MPa and when the content of Kaolin in NaAlg was 70 wt.%. The filtration of BSA solution and oil-water emulsion indicated that the kaolin/CaAlg composite filtration membrane exhibited good anti-fouling properties. The rejection of Brilliant Blue G250, Congo red, and methylene blue by the kaolin/CaAlg filtration membrane was 100%, 95.22%, and 62.86%, respectively. The removal rate of Cd2+ reached 99.69%, with a flux of 17.06 L/m2·h at 0.1 MPa.

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50

Razi, Fachrul, Sri Mulyati e Nasrul Arahman. "The performance of bovine serum albumin filtration by using polyethersulfone-Tetronic 304 blend Ultrafiltration Membrane". F1000Research 8 (24 giugno 2019): 953. http://dx.doi.org/10.12688/f1000research.18740.1.

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Abstract (sommario):

Background: Membrane technology has been widely applied for protein purification. In applications for protein separation, a membrane with stable filtration performance is necessary. In this work, two types of hollow fiber membranes with different characteristic were used to study the filtration profile of bovine serum albumin. Methods: A single piece of hollow fiber module was used for ultrafiltration testing using UF0 and UFT304 membranes. Flux and rejection of BSA solution were collected based on a pressure-driven inside filtration model. Results: Ultrafiltration experiments showed that the flux of UFT304 membrane was higher than that of UF0 membrane in all applied pressure condition. Solute rejection was achieved up to 90% for ultrafiltration of BSA solution by using UF0 membrane obtained on the operating pressure of 0.5 atm. Conclusion: In general, UFT304 membranes has better ultrafiltration performance for BSA separation than UF0 membranes. The UFT304 membrane has a more stable flux for up to two hours of filtration.

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