Analysis of an ultrafiltration model: Influence of operational conditions

Ultrafiltration is a widely used technique to remove hazardous pollutants from wastewaters. As ultrafiltration is a dynamic process, non steady-state UF models have been widely investigated and described in the literature. The main equations of most dynamic models found in the literature can be rearranged and simplified into a linear equation. In this work, experimental results from UF tests were expressed in terms of TMP2/J(P)(2) as a function of time to check linearity. Transmembrane pressure (TMP), feed concentration (FC), temperature and crossflow velocity (CFV) were varied during the experiments. The feed consisted in an aqueous solution of polyethylene glycol of 35 kg/mol molecular weight. The experimental results confirmed a linear relationship when TMP2/J(P)(2) was plotted vs. time. For severe fouling conditions, the linearity found when plotting experimental values of initial membrane fouling resistance vs. TMP was very high. A linear correlation between the initial membrane fouling resistance and the temperature was also found for the experimental conditions tested. However, it was found that, above 25 degrees C, increasing temperature did not result in a noticeable reduction of the gel layer resistance. The quotient r(c)/r(g) as a function of TMP and CFV was also evaluated to check if it followed any pattern. (C) 2011 Elsevier B.V. All rights reserved.Vincent Vela, MC.; Cuartas Uribe, BE.; Alvarez Blanco, S.; Lora García, J. (2012). Analysis of an ultrafiltration model: Influence of operational conditions. Desalination. 284:14-21. doi:10.1016/j.desal.2011.08.030S142128

Analysis of fouling resistances under dynamic membrane filtration

The mechanisms of fouling in the ultrafiltration of polyethylene glycol (PEG) are analysed using the complete blocking and the intermediate blocking Hermia's models adapted to crossflow filtration. The parameters of these models were theoretically estimated. The predicted results were compared with experimental data. Ultrafiltration experiments were performed with Carbosep M2 monotubular ceramic (Orelis, S.A. (France)). The fouling ultrafiltration experiments were carried out at a constant temperature and feed concentration and different feed flow rates and transmembrane pressures. The precision in the predictions is very high. The results showed that the phenomenon controlling fouling was intermediate blocking for high fouling conditions. © 2011 Elsevier B.V.The authors of this work wish to gratefully acknowledge the financial support of the Spanish Ministry of Science and Technology (MCYT) through its project no. CTQ2005-03398.Vincent Vela, MC.; Cuartas Uribe, BE.; Alvarez Blanco, S.; Lora García, J. (2011). Analysis of fouling resistances under dynamic membrane filtration. Chemical Engineering and Processing: Process Intensification. 50(4):404-408. https://doi.org/10.1016/j.cep.2011.02.010S40440850

Modelado dinámico de procesos de ultrafiltración tangencial aplicados a la separación de macromoléculas

En la presente Tesis Doctoral se analizó la aplicación de modelos dinámicos tanto teóricos como semi-empíricos para predecir el descenso de la densidad de flujo de permeado con el tiempo debido al ensuciamiento en procesos de ultrafiltración tangencial de macromoléculas. Los fenómenos de ensuciamiento están presentes en todas las aplicaciones de los procesos de ultrafiltración y son el principal factor limitante en la aplicación de la tecnología de membranas. Se realizaron ensayos en planta piloto con dos membranas cerámicas de ultrafiltración y con una alimentación consistente en una disolución acuosa de polietilenglicol. En los ensayos experimentales se varió la velocidad tangencial, la presión transmembranal, la concentración de polietilenglicol y la temperatura. Los datos experimentales obtenidos se compararon con los resultados predichos por los modelos. Los resultados demostraron la imposibilidad de predecir de manera totalmente teórica la variación de la densidad de flujo de permeado con el tiempo bajo diferentes condiciones experimentales. Uno de los motivos es la dificultad para estimar de forma teórica todos los parámetros de los modelos. Sin embargo, por medio de los Modelos de Hermia modificados para filtración tangencial, se logró predecir con buen grado de ajuste a los resultados experimentales la variación de la densidad de flujo de permeado con el tiempo para todas las condiciones experimentales ensayadas utilizando únicamente como datos experimentales la densidad de flujo de permeado inicial y estacionaria. El resto de los parámetros se calcularon a partir de correlaciones teóricas.Vincent Vela, MC. (2006). Modelado dinámico de procesos de ultrafiltración tangencial aplicados a la separación de macromoléculas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1871Palanci

Evaluation of fouling resistances during the ultrafiltration of whey model solutions

[EN] In the last decades, the ultrafiltration of whey has grown in importance as a "green" technique. However, since fouling is an important drawback, researchers focused on its prediction by mathematical models. In this work, three ultrafiltration membranes of different molecular weight cut-offs and materials were used to ultrafilter whey model solutions of different protein concentrations. As a novelty, a resistance-in-series model that accounts for the time evolution of the fouling resistances was considered. The results demonstrated that the higher the protein and salt concentrations in the feed solutions were, the greater the fouling degree was. The resistance-in-series model was accurately fitted to the experimental data for each membrane and feed solution used. The results showed that the resistance due to adsorption dominated the first minutes of operation, while the membrane characteristics (surface roughness and hydrophilicity/hydrophobicity) played an important role in the growth of the cake layer. (C) 2017 Elsevier Ltd. All rights reserved.The authors of this work wish to gratefully acknowledge the financial support provided by the Spanish Ministry of Science and Innovation through its project CTM2010-20186.Corbatón Báguena, MJ.; Alvarez Blanco, S.; Vincent Vela, MC. (2018). Evaluation of fouling resistances during the ultrafiltration of whey model solutions. Journal of Cleaner Production. 172:358-367. https://doi.org/10.1016/j.jclepro.2017.10.149S35836717

Green management of wet olive pomace by means of ultrafiltration of an aqueous extract of phenolic compounds

[EN] Wet olive pomace is a major by-product generated by olive mills. To contribute to the circular economy of the olive industry, the recovery of interesting compounds from wet olive pomace was assessed. To that end, a previously optimized solid-liquid extraction, only employing water as the extractant, was first applied to the wet olive pomace. Afterwards, an ultrafiltration process to treat the obtained extract was developed. Several membranes (UP005, UH030, UH050, and UP150, from Microdyn Nadir) were studied, in a wide range of cross-flow velocities (1.5¿3.5 m/s) and transmembrane pressures (0.75¿5.5 bar). By a thorough characterization of the ultrafiltration streams by LC-ESI-QToF-MS, it was possible to describe the evolution of the rejection of 29 phenolic compounds. Some adsorption processes were also observed in the ultrafiltration process. The UP005 and UH030 membranes displayed satisfactory values of permeate flux and rejection. Both membranes efficiently retained a high fraction of the total solids, chemical oxygen demand, and color. On the contrary, the phenolic compounds were obtained in the ultrafiltration permeate, which constitutes a source of antioxidant molecules with applications in cosmetics, pharmacy, and nutraceutics.This work was supported by the research project CIAICO/2021/333, funded by the Regional Government of Valencia (Generalitat Valenciana) . The predoctoral grant PRE2018-08524 was funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future.Sánchez-Arévalo, CM.; Vincent Vela, MC.; Alvarez Blanco, S. (2023). Green management of wet olive pomace by means of ultrafiltration of an aqueous extract of phenolic compounds. Environmental Technology & Innovation. 32. https://doi.org/10.1016/j.eti.2023.1033853

Exploring the extraction of the bioactive content from the two-phase olive mill waste and further purification by ultrafiltration

[EN] The two-phase olive mill waste is enormously produced in the Mediterranean area. This major waste is significantly rich in bioactive compounds that are highly valued by industry, such as phenolic and triterpenic compounds. Here, a thorough study of the most suitable solvent, extraction time and temperature for the largevolume, solid-liquid extraction of bioactive compounds has been made, in order to achieve maximum concentrations of the target compounds. Ultrasound effect has been considered. A deep characterization of the extracts by high-performance liquid chromatography coupled with electrospray-quadrupole-time of flight-mass spectrometry (LC-ESI-qToF-MS) has contributed to evaluate the effect of the operational parameters on the extraction performance. Forty-four compounds have been found and classified in their corresponding chemical families. At the optimum experimental conditions (EtOH 50% (v/v), 40 degrees C, ultrasound-assisted), more than 6.8 mg/g of bioactive content was recovered, and it was later purified by means of ultrafiltration. The membrane UP005 retained a significant percentage of the organic matter, whereas most of the bioactive compounds were recovered in the permeate. This contributed not only to revalorize this waste, but also to reduce its organic load and phytotoxicity, thus protecting the ecosystem of the final disposal zone of the residue.Funding Grant CTM2017-88645-R, funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe. Additionally, the grant PRE2018-08524 was funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future. Funding for open access charge: CRUE-Universitat Politècnica de València.Sánchez-Arévalo, CM.; Iborra Clar, A.; Vincent Vela, MC.; Alvarez Blanco, S. (2022). Exploring the extraction of the bioactive content from the two-phase olive mill waste and further purification by ultrafiltration. LWT - Food Science and Technology. 165:1-12. https://doi.org/10.1016/j.lwt.2022.11374211216

Utilization of NaCl solutions to clean ultrafiltration membranes fouled by whey protein concentrates

In this work, whey protein concentrate (WPC) solutions at different concentrations (22.2, 333 and 150 g L-1) were used to foul three ultrafiltration (UF) membranes of different materials and molecular weight cut-offs (MWCOs): a polyethersulfone (PES) membrane of 5 kDa, a ceramic ZrO2-TiO2 membrane of 15 kDa and a permanently hydrophilic polyethersulfone (PESH) membrane of 30 kDa. NaCl solutions at different salt concentrations, temperatures and crossflow velocities were used to clean the UF membranes tested. The cleaning efficiency was related to the MWCO, membrane material and operating conditions during fouling and cleaning steps. NaCl solutions were able to completely clean the membranes fouled with the WPC solutions at the lowest concentration tested. As WPC concentration increased, the hydraulic cleaning efficiency (HCE) decreased. The results demonstrated that an increase in temperature and crossflow velocity of the cleaning solution caused an increase in the HCE. Regarding NaCl concentration, the HCE increased up to an optimal value. As the concentration was greater than this value, the cleaning efficiency decreased. In addition, an equation that correlates the cleaning efficiency to the operating parameters studied in this work (temperature, NaCl concentration, crossflow velocity in the cleaning procedure and WPC concentration during the fouling step) was developed and then, an optimization analysis was performed to determine the values of the parameters that lead to a 100% cleaning efficiency.The authors of this work wish to gratefully acknowledge the financial support from the Spanish Ministry of Science and Innovation through the project CTM2010-20186.Corbatón Báguena, MJ.; Alvarez Blanco, S.; Vincent Vela, MC.; Lora-García, J. (2015). Utilization of NaCl solutions to clean ultrafiltration membranes fouled by whey protein concentrates. Separation and Purification Technology. 150:95-101. https://doi.org/10.1016/j.seppur.2015.06.039S9510115

Improving the Signal Propagation at 2.4 GHz Using Conductive Membranes

© 2017 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works[EN] When IEEE 802.11 at 2.4-GHz signal crosses different surfaces, it is generally reduced, but we have seen that it does not happen for all materials. Conductive membranes are able to transport electric charges when they are submerged into water with electrolytes, so we take profit of their features in order to know in which cases the received signal strength indicator (RSSI) can be improved. In order to achieve our goal, the RSSI is measured at different distances using different environments for the membranes, air, and water environment with different conductivities (distillated water, tap water, and salty water). Results show that different membranes environment produce different signal strengths. Moreover, they can be positive or negative depending on the environment of the membranes and the distance from the access point. In some cases, we registered an increase of more than 14 dBm of the signal when we were using those membranes.This work was supported in part by the "Ministerio de Ciencia e Innovacion," through the "Plan Nacional de I+D+i 2008-2011" in the "Subprograma de Proyectos de Investigacion Fundamental," project TEC2011-27516.Parra-Boronat, L.; Sendra, S.; Vincent Vela, MC.; García Gabaldón, M.; Lloret, J. (2017). Improving the Signal Propagation at 2.4 GHz Using Conductive Membranes. IEEE Systems Journal. 11(4):2315-2324. https://doi.org/10.1109/JSYST.2015.2496204S2315232411

Analysis of two ultrafiltration fouling models and estimation of model parameters as a function of operational conditions

This work analyses the measure of fit of experimental data of permeate flux decline with time for ultrafiltration experiments performed with polyethylene glycol aqueous solutions to two different ultrafiltration models. A feed solution of 5 kg/m of polyethylene glycol and a monotubular ceramic membrane of - were used in the experiments. The first model considered was developed by Ho and Zydney and it considers two different fouling mechanisms: pore blocking and gel layer formation. The second model was proposed by Yee et al. It is an exponential model that considers three stages: concentration polarization, molecule deposition on the membrane surface and long-term fouling. The results show that both models give very accurate predictions for the severe fouling conditions (high transmembrane pressures and low crossflow velocities). However, both models cannot explain the experimental results obtained for all the experimental conditions tested. An equation for Ho and Zydney's model parameters as a function of operating conditions was obtained by means of multiple regression analysis.The authors of this work wish to gratefully acknowledge the financial support of the Universidad Politecnica de Valencia through the Project No. 2010.1009 and the Spanish Ministry of Science and Technology through the project CTM2010-20186.Corbatón Báguena, MJ.; Vincent Vela, MC.; Alvarez Blanco, S.; Lora García, J. (2013). Analysis of two ultrafiltration fouling models and estimation of model parameters as a function of operational conditions. Transport in Porous Media. 99(2):391-411. https://doi.org/10.1007/s11242-013-0192-4S391411992Alventosa-deLara, E., Barredo-Damas, S., Alcaina-Miranda, M.I., Iborra-Clar, M.I.: Ultrafiltration technology with a ceramic membrane for reactive dye removal: optimization of membrane performance. J. Hazard. Mater. 209–210, 492–500 (2012)Baldasso, C., Barros, T.C., Tessaro, I.C.: Concentration and purification of whey proteins by ultrafiltration. Desalination 278, 381–386 (2011)Bhattacharjee, C., Datta, S.: Analysis of polarized layer resistance during ultrafiltration of PEG-6000: an approach based on filtration theory. Sep. Purif. Technol. 33, 115–126 (2003)Buetehorn, S., Carstensen, F., Wintgens, T., Melin, T., Volmering, D., Vossenkaul, K.: Permeate flux decline in crossflow microfiltration at constant pressure. Desalination 250, 985–990 (2010)Chan, R., Chen, V.: Characterization of protein fouling on membranes: opportunities and challenges. J. Membr. Sci. 242, 169–188 (2004)Cheryan, M.: Ultrafiltration and Microfiltration Handbook. Technomic Publishing Company, Inc., Lancaster (1998)de Barros, S.T.D., Andrade, C.M.G., Mendes, E.S., Peres, L.: Study of fouling mechanism in pineapple juice clarification by ultrafiltration. J. Membr. Sci. 215, 213–224 (2003)de la Casa, E.J., Guadix, A., Ibáñez, R., Camacho, F., Guadix, E.M.: A combined fouling model to describe the influence of the electrostatic environment on the cross-flow microfiltration of BSA. J. Membr. Sci. 318, 247–254 (2008)Espina, V., Jaffrin, M.Y., Ding, L., Cancino, B.: Fractionation of pasteurized skim milk proteins by dynamic filtration. Food Res. Int. 43, 1335–1346 (2010)Fernández-Sempere, J., Ruiz-Beviá, F., García-Algado, P., Salcedo-Díaz, R.: Visualization and modeling of the polarization layer and a reversible adsorption process in PEG-10000 dead-end ultrafiltration. J. Membr. Sci. 342, 279–290 (2009)Field, R.W., Wu, D., Howell, J.A., Gupta, B.B.: Critical flux concept for microfiltration fouling. J. Membr. Sci. 100, 259–272 (1995)Hermia, J.: Constant pressure blocking filtration laws—application to powerlaw non-Newtonian fluids. Trans. IChemE 60, 183–187 (1982)Ho, C.-C., Zydney, A.L.: A combined pore blockage and cake filtration model for protein fouling during microfiltration. J. Colloid Interface Sci. 232, 389–399 (2000)Karasu, K., Yoshikawa, S., Ookawara, S., Ogawa, K., Kentish, S.E., Stevens, G.W.: A combined model for the prediction of the permeation flux during the cross-flow ultrafiltration of a whey suspension. J. Membr. Sci. 361, 71–77 (2010)Ko, M.K., Pellegrino, J.J.: Determination of osmotic pressure and fouling resistances and their effects on performance of ultrafiltration membranes. J. Membr. Sci. 74, 141–157 (1992)Lin, S.-H., Hung, C.-L., Juang, R.-S.: Applicability of the exponential time dependence of flux decline during dead-end ultrafiltration of binary protein solutions. Chem. Eng. J. 145, 211–217 (2008)Mondal, S., De, S.: A fouling model for steady state crossflow membrane filtration considering sequential intermediate pore blocking and cake formation. Sep. Purif. Technol. 75, 222–228 (2010)Mondor, M., Girard, B., Moresoli, C.: Modeling flux behaviour for membrane filtration of apple juice. Food Res. Int. 33, 539–548 (2000)Muthukumaran, S., Kentish, S.E., Ashokkumar, M., Stevens, G.W.: Mechanisms for the ultrasonic enhancement of dairy whey ultrafiltration. J. Membr. Sci. 258, 106–114 (2005)Peng, H., Tremblay, A.Y.: Membrane regeneration and filtration modeling in treating oily wastewaters. J. Membr. Sci. 324, 59–66 (2008)Popović, S., Milanović, S., Iličić, M., Djurić, M., Tekić, M.: Flux recovery of tubular ceramic membranes fouled with whey proteins. Desalination 249, 293–300 (2009)Purkait, M.K., DasGupta, S., De, S.: Resistance in series model for micellar enhanced ultrafiltration of eosin dye. J. Colloid Interface Sci. 270, 496–506 (2004)Rinaldoni, A.N., Taragaza, C.C., Campderrós, M.E., Pérez, Padilla A.: Assessing performance of skim milk ultrafiltration by using technical parameters. J. Food Eng. 92, 226–232 (2009)Santafé-Moros, A., Gozálvez-Zafrilla, J.M.: Nanofiltration study of the interaction between bicarbonate and nitrate ions. Desalination 250, 773–777 (2010)Song, L.: Flux decline in crossflow microfiltration and ultrafiltration: mechanisms and modeling of membrane fouling. J. Membr. Sci. 139, 183–200 (1998)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Gozálvez Zafrilla, J.M., Bergantiños, Rodríguez E.: Modelling of flux decline in crossflow ultrafiltration of macromolecules: comparison between predicted and experimental results. Desalination 204, 328–334 (2007a)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Gozálvez Zafrilla, J.M., Bergantiños, Rodríguez E.: Utilization of a shear induced diffusion model to predict permeate flux in the crossflow ultrafiltration of macromolecules. Desalination 206, 61–68 (2007b)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Bergantiños, Rodríguez E.: Analysis of membrane pore blocking models applied to the ultrafiltration of PEG. Sep. Purif. Technol. 62, 489–498 (2008a)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Bergantiños, Rodríguez E.: Fouling dynamics modelling in the ultrafiltration of PEGs. Desalination 222, 451–456 (2008b)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Bergantiños, Rodríguez E.: Analysis of membrane pore blocking models to crossflow ultrafiltration in the ultrafiltration of PEG. Chem. Eng. J. 149, 232–241 (2009)Vincent-Vela, C., Cuartas-Uribe, B., Álvarez-Blanco, S., Lora-García, J., Bergantiños-Rodríguez, E.: Analysis of ultrafiltration processes with dilatant macromolecular solutions by means of dimensionless numbers and hydrodynamic parameters. Sep. Purif. Technol. 75, 332–339 (2010)Wang, L., Song, L.: Flux decline in crossflow microfiltration and ultrafiltration: experimental verification of fouling dynamics. J. Membr. Sci. 160, 41–50 (1999)Yee, K.W.K., Wiley, D.E., Bao, J.: A unified model of the time dependence of flux decline for the long-term ultrafiltration of whey. J. Membr. Sci. 332, 69–70 (2009

Automated Program Analysis for Novice Programmers

[EN] This paper describes how to adapt a static code analyzer to provide feedback novice programmers and their teachers. Current analyzers have been built to give feedback to experienced programmers who work on software projects or systems. The type of feedback and the type of analysis of these tools focusses on mistakes that are relevant within that context, and help with debugging software system. When teaching novice programmers this type of advice is often not particularly useful. It would be instead more useful to use these techniques to identify problem in the understanding of students of important programming concepts. This paper first explores in what respect static analyzers support the learning and teaching of programming, and what can be implemented based on existing static analysis technology. It presents an extension of static analyzer PMD to create feedback that is more valuable to novice programmers. To answer the question if these techniques are able to find conceptual mistakes that are characteristic for novice programmers make, we ran it over a number of student projects, and compared these results with publicly available mature software projects.Blok, T.; Fehnker, A. (2017). Automated Program Analysis for Novice Programmers. En Proceedings of the 3rd International Conference on Higher Education Advances. Editorial Universitat Politècnica de València. 1138-1146. https://doi.org/10.4995/HEAD17.2017.5533OCS1138114