Comparison of different model solutions to simulate membrane fouling in the ultrafiltration of a secondary effluent from a municipal wastewater treatment plant

The quality of the secondary treatment effluent (STE) from a municipal wastewater treatment plant (MWWTP) is not good enough for some applications such as agriculture. Membrane ultrafiltration (UF) has been proven to be a reliable tertiary treatment to achieve the needed water quality. The productivity of the UF processes depends on the membrane fouling. The aim of this work is to prepare a model wastewater that could mimic the fouling trend of a STE wastewater from a MWWTP. Several model wastewaters consisting of different proteins and carbohydrates were used in the UF experiments. UF was also performed with a STE. The membrane used in the UF tests was a UFCM5 from Norit X-flow® hydrophilic polyethersulfone/polyvinylpyrrolidone blend hollow-fiber UF membrane of 200 KDa molecular weight cut-off with a fiber diameter of 1.5 mm. Membrane configuration was inside-out. UF tests with model wastewater and STE wastewater were compared. The results showed that the best model wastewater, which represents the fouling trend of STE wastewater is the model wastewater whose composition is 15 mg/l of bovine serum albumin and 5.5 mg/l of dextran.The authors of this work wish to gratefully acknowledge the financial support from the Generalitat Valenciana through the program "Ayudas para la realizacion de proyectos I+D para grupos de investigacion emergentes GV/2013."Tora Grau, M.; Soler Cabezas, JL.; Vincent Vela, MC.; Mendoza Roca, JA.; Martínez Francisco, FJ. (2014). Comparison of different model solutions to simulate membrane fouling in the ultrafiltration of a secondary effluent from a municipal wastewater treatment plant. Desalination and Water Treatment. 1-7. https://doi.org/10.1080/19443994.2014.939865S17Delgado, S., Dı́az, F., Vera, L., Dı́az, R., & Elmaleh, S. (2004). Modelling hollow-fibre ultrafiltration of biologically treated wastewater with and without gas sparging. Journal of Membrane Science, 228(1), 55-63. doi:10.1016/j.memsci.2003.09.011Qin, J.-J., Oo, M. H., Lee, H., & Kolkman, R. (2004). Dead-end ultrafiltration for pretreatment of RO in reclamation of municipal wastewater effluent. Journal of Membrane Science, 243(1-2), 107-113. doi:10.1016/j.memsci.2004.06.010Konieczny, K. (1998). Disinfection of surface and ground waters with polymeric ultrafiltration membranes. Desalination, 119(1-3), 251-258. doi:10.1016/s0011-9164(98)00166-0Madaeni, S. S., Fane, A. G., & Grohmann, G. S. (1995). Virus removal from water and wastewater using membranes. Journal of Membrane Science, 102, 65-75. doi:10.1016/0376-7388(94)00252-tArnal Arnal, J. M., Sancho Fernández, M., Martín Verdú, G., & Lora García, J. (2001). Design of a membrane facility for water potabilization and its application to Third World countries. Desalination, 137(1-3), 63-69. doi:10.1016/s0011-9164(01)00205-3Arévalo, J., Garralón, G., Plaza, F., Moreno, B., Pérez, J., & Gómez, M. Á. (2009). Wastewater reuse after treatment by tertiary ultrafiltration and a membrane bioreactor (MBR): a comparative study. Desalination, 243(1-3), 32-41. doi:10.1016/j.desal.2008.04.013Katsoufidou, K., Yiantsios, S. G., & Karabelas, A. J. (2008). An experimental study of UF membrane fouling by humic acid and sodium alginate solutions: the effect of backwashing on flux recovery. Desalination, 220(1-3), 214-227. doi:10.1016/j.desal.2007.02.038Muthukumaran, S., Nguyen, D. A., & Baskaran, K. (2011). Performance evaluation of different ultrafiltration membranes for the reclamation and reuse of secondary effluent. Desalination, 279(1-3), 383-389. doi:10.1016/j.desal.2011.06.040Henderson, R. K., Subhi, N., Antony, A., Khan, S. J., Murphy, K. R., Leslie, G. L., … Le-Clech, P. (2011). Evaluation of effluent organic matter fouling in ultrafiltration treatment using advanced organic characterisation techniques. Journal of Membrane Science, 382(1-2), 50-59. doi:10.1016/j.memsci.2011.07.041Fan, L., Nguyen, T., Roddick, F. A., & Harris, J. L. (2008). Low-pressure membrane filtration of secondary effluent in water reuse: Pre-treatment for fouling reduction. Journal of Membrane Science, 320(1-2), 135-142. doi:10.1016/j.memsci.2008.03.058Xiao, D., Li, W., Chou, S., Wang, R., & Tang, C. Y. (2012). A modeling investigation on optimizing the design of forward osmosis hollow fiber modules. Journal of Membrane Science, 392-393, 76-87. doi:10.1016/j.memsci.2011.12.006Kaya, Y., Barlas, H., & Arayici, S. (2011). Evaluation of fouling mechanisms in the nanofiltration of solutions with high anionic and nonionic surfactant contents using a resistance-in-series model. Journal of Membrane Science, 367(1-2), 45-54. doi:10.1016/j.memsci.2010.10.037Yu, C.-H., Fang, L.-C., Lateef, S. K., Wu, C.-H., & Lin, C.-F. (2010). Enzymatic treatment for controlling irreversible membrane fouling in cross-flow humic acid-fed ultrafiltration. Journal of Hazardous Materials, 177(1-3), 1153-1158. doi:10.1016/j.jhazmat.2010.01.022Gao, W., Liang, H., Ma, J., Han, M., Chen, Z., Han, Z., & Li, G. (2011). Membrane fouling control in ultrafiltration technology for drinking water production: A review. Desalination, 272(1-3), 1-8. doi:10.1016/j.desal.2011.01.051Amin Saad, M. (2004). Early discovery of RO membrane fouling and real-time monitoring of plant performance for optimizing cost of water. Desalination, 165, 183-191. doi:10.1016/j.desal.2004.06.021Jayalakshmi, A., Rajesh, S., & Mohan, D. (2012). Fouling propensity and separation efficiency of epoxidated polyethersulfone incorporated cellulose acetate ultrafiltration membrane in the retention of proteins. Applied Surface Science, 258(24), 9770-9781. doi:10.1016/j.apsusc.2012.06.028Qu, F., Liang, H., Wang, Z., Wang, H., Yu, H., & Li, G. (2012). Ultrafiltration membrane fouling by extracellular organic matters (EOM) of Microcystis aeruginosa in stationary phase: Influences of interfacial characteristics of foulants and fouling mechanisms. Water Research, 46(5), 1490-1500. doi:10.1016/j.watres.2011.11.051Wang, C., Li, Q., Tang, H., Yan, D., Zhou, W., Xing, J., & Wan, Y. (2012). Membrane fouling mechanism in ultrafiltration of succinic acid fermentation broth. Bioresource Technology, 116, 366-371. doi:10.1016/j.biortech.2012.03.099Nataraj, S., Schomäcker, R., Kraume, M., Mishra, I. M., & Drews, A. (2008). Analyses of polysaccharide fouling mechanisms during crossflow membrane filtration. Journal of Membrane Science, 308(1-2), 152-161. doi:10.1016/j.memsci.2007.09.060Zator, M., Ferrando, M., López, F., & Güell, C. (2007). Membrane fouling characterization by confocal microscopy during filtration of BSA/dextran mixtures. Journal of Membrane Science, 301(1-2), 57-66. doi:10.1016/j.memsci.2007.05.038Xiao, K., Wang, X., Huang, X., Waite, T. D., & Wen, X. (2009). Analysis of polysaccharide, protein and humic acid retention by microfiltration membranes using Thomas’ dynamic adsorption model. Journal of Membrane Science, 342(1-2), 22-34. doi:10.1016/j.memsci.2009.06.016Nigam, M. O., Bansal, B., & Chen, X. D. (2008). Fouling and cleaning of whey protein concentrate fouled ultrafiltration membranes. Desalination, 218(1-3), 313-322. doi:10.1016/j.desal.2007.02.027MOUROUZIDISMOUROUZIS, S., & KARABELAS, A. (2006). Whey protein fouling of microfiltration ceramic membranes—Pressure effects. Journal of Membrane Science, 282(1-2), 124-132. doi:10.1016/j.memsci.2006.05.012Carić, M. Đ., Milanović, S. D., Krstić, D. M., & Tekić, M. N. (2000). Fouling of inorganic membranes by adsorption of whey proteins. Journal of Membrane Science, 165(1), 83-88. doi:10.1016/s0376-7388(99)00221-5Tasselli, F., Cassano, A., & Drioli, E. (2007). Ultrafiltration of kiwifruit juice using modified poly(ether ether ketone) hollow fibre membranes. Separation and Purification Technology, 57(1), 94-102. doi:10.1016/j.seppur.2007.03.007Hao, Y., Moriya, A., Maruyama, T., Ohmukai, Y., & Matsuyama, H. (2011). Effect of metal ions on humic acid fouling of hollow fiber ultrafiltration membrane. Journal of Membrane Science, 376(1-2), 247-253. doi:10.1016/j.memsci.2011.04.035Marcos, B., Moresoli, C., Skorepova, J., & Vaughan, B. (2009). CFD modeling of a transient hollow fiber ultrafiltration system for protein concentration. Journal of Membrane Science, 337(1-2), 136-144. doi:10.1016/j.memsci.2009.03.036Chung, T.-S., Qin, J.-J., & Gu, J. (2000). Effect of shear rate within the spinneret on morphology, separation performance and mechanical properties of ultrafiltration polyethersulfone hollow fiber membranes. Chemical Engineering Science, 55(6), 1077-1091. doi:10.1016/s0009-2509(99)00371-1Nguyen, T.-A., Yoshikawa, S., Karasu, K., & Ookawara, S. (2012). A simple combination model for filtrate flux in cross-flow ultrafiltration of protein suspension. Journal of Membrane Science, 403-404, 84-93. doi:10.1016/j.memsci.2012.02.026Domínguez Chabaliná, L., Rodríguez Pastor, M., & Rico, D. P. (2013). Characterization of soluble and bound EPS obtained from 2 submerged membrane bioreactors by 3D-EEM and HPSEC. Talanta, 115, 706-712. doi:10.1016/j.talanta.2013.05.062Viebke, C. (2000). Determination of molecular mass distribution of κ-carrageenan and xanthan using asymmetrical flow field-flow fractionation. Food Hydrocolloids, 14(3), 265-270. doi:10.1016/s0268-005x(99)00066-1Kelly, S. T., & Zydney, A. L. (1995). Mechanisms for BSA fouling during microfiltration. Journal of Membrane Science, 107(1-2), 115-127. doi:10.1016/0376-7388(95)00108-oHwang, K.-J., & Sz, P.-Y. (2011). Membrane fouling mechanism and concentration effect in cross-flow microfiltration of BSA/dextran mixtures. Chemical Engineering Journal, 166(2), 669-677. doi:10.1016/j.cej.2010.11.04

Study of the influence of operational conditions and hollow-fiber diameter on the ultrafiltration performance of a secondary treatment effluent

Secondary treatment effluents from municipal wastewater treatment plants (MWWTP) must achieve high water quality standards for their reuse in agriculture. To achieve these standards, ultrafiltration (UF) process, which is economically feasible, is carried out. However, UF has a drawback, membrane fouling, which causes operating difficulties and an increment of the operating cost. In order to minimize this phenomenon, it is important to determine the best operational conditions. Wastewater samples provided by MWWTP have a lot of variability in their composition due to factors such as temperature, efficiency of the secondary treatment, etc. Besides, the soluble microbial products of the secondary effluent are dependent on the type of the biological treatment implemented and its operating conditions. A model wastewater feed solution was prepared consisting of 15 mg/L of bovine serum albumin and 5.5 mg/L of dextran. In this research, UF tests were performed with the optimal simulated wastewater using two membranes UFCM5 Norit X-flow® hollow-fiber: one of them with a fiber diameter of 1.5 mm and the other one with a fiber diameter of 0.8 mm. The operational conditions, which influence membrane fouling, were varied in the range of 62 100 kPa for transmembrane pressure (TMP) and in the range of 0.8 1.2 m/s for cross-flow velocity (CFV). The best operational conditions were selected in terms of higher permeate flux. The highest permeate flux was obtained for the membrane of 0.8 mm and the lower energy consumption was achieved at a CFV of 1.2 m/s and a TMP of 62 kPa.Torà Grau, M.; Soler Cabezas, JL.; Vincent Vela, MC.; Mendoza Roca, JA.; Martínez Francisco, FJ. (2015). Study of the influence of operational conditions and hollow-fiber diameter on the ultrafiltration performance of a secondary treatment effluent. Desalination and Water Treatment. 1-7. doi:10.1080/19443994.2015.1118887S1

Ultrafiltration fouling trend simulation of a municipal wastewater treatment plant effluent with model wastewater

Secondary treatment effluents from Municipal Wastewater Treatment Plants require tertiary treatments to be reused in agriculture. Among tertiary treatment technologies, ultrafiltration has been proven to be a reliable reclamation process. Nevertheless this technique has an important disadvantage: membrane fouling. This phenomenon causes decline in permeate flux with time and increases the operational costs. Due to the fact that secondary effluents from Municipal Wastewater Treatment Plants contain a large amount of different compounds and that there is certain variability in their composition, the use of a simplified model wastewater consisting of only few compounds may help to simulate better the ultrafiltration fouling trend. The main secondary treatment effluent components responsible for fouling membrane during ultrafiltration tests are extracellular polymeric substances. These substances are mainly composed of proteins and polysaccharides, thus they are commonly used to prepare model wastewaters. This work consisted in two parts. Firstly, a model wastewater was selected among different model solutions mimicking secondary treatment effluent. Secondly, ultrafiltration behaviour of the selected model solution was compared with the behaviour of the secondary effluent in the ultrafiltration tests at different cross-flow velocities and transmembrane pressures. The membrane used in the ultrafiltration tests was UFCM5 Norit X-flow® hollow-fiber. To prepare model wastewaters, three parameters (proteins and carbohydrates concentrations and chemical oxygen demand) were considered. The model wastewater that represented the best the fouling trend of the secondary treatment effluent had a composition of 15 mg/l of bovine serum albumin and 5.5 mg/l of dextranThe authors wish to gratefully acknowledge the financial support of the Generalitat Valenciana through the project "Ayudas para la realizacion de proyectos I+D para grupos de investigacion emergentes GV/2013."Tora Grau, M.; Soler Cabezas, JL.; Vincent Vela, MC.; Mendoza Roca, JA.; Martínez Francisco, FJ. (2015). Ultrafiltration fouling trend simulation of a municipal wastewater treatment plant effluent with model wastewater. Desalination and Water Treatment. 1-9. doi:10.1080/19443994.2014.999714S19Qin, J.-J., Oo, M. H., Lee, H., & Kolkman, R. (2004). Dead-end ultrafiltration for pretreatment of RO in reclamation of municipal wastewater effluent. Journal of Membrane Science, 243(1-2), 107-113. doi:10.1016/j.memsci.2004.06.010Arévalo, J., Garralón, G., Plaza, F., Moreno, B., Pérez, J., & Gómez, M. Á. (2009). Wastewater reuse after treatment by tertiary ultrafiltration and a membrane bioreactor (MBR): a comparative study. Desalination, 243(1-3), 32-41. doi:10.1016/j.desal.2008.04.013Katsoufidou, K., Yiantsios, S. G., & Karabelas, A. J. (2008). An experimental study of UF membrane fouling by humic acid and sodium alginate solutions: the effect of backwashing on flux recovery. Desalination, 220(1-3), 214-227. doi:10.1016/j.desal.2007.02.038Muthukumaran, S., Nguyen, D. A., & Baskaran, K. (2011). Performance evaluation of different ultrafiltration membranes for the reclamation and reuse of secondary effluent. Desalination, 279(1-3), 383-389. doi:10.1016/j.desal.2011.06.040Henderson, R. K., Subhi, N., Antony, A., Khan, S. J., Murphy, K. R., Leslie, G. L., … Le-Clech, P. (2011). Evaluation of effluent organic matter fouling in ultrafiltration treatment using advanced organic characterisation techniques. Journal of Membrane Science, 382(1-2), 50-59. doi:10.1016/j.memsci.2011.07.041Muthukumaran, S., Jegatheesan, J. V., & Baskaran, K. (2013). Comparison of fouling mechanisms in low-pressure membrane (MF/UF) filtration of secondary effluent. Desalination and Water Treatment, 52(4-6), 650-662. doi:10.1080/19443994.2013.826324Yu, C.-H., Fang, L.-C., Lateef, S. K., Wu, C.-H., & Lin, C.-F. (2010). Enzymatic treatment for controlling irreversible membrane fouling in cross-flow humic acid-fed ultrafiltration. Journal of Hazardous Materials, 177(1-3), 1153-1158. doi:10.1016/j.jhazmat.2010.01.022Gao, W., Liang, H., Ma, J., Han, M., Chen, Z., Han, Z., & Li, G. (2011). Membrane fouling control in ultrafiltration technology for drinking water production: A review. Desalination, 272(1-3), 1-8. doi:10.1016/j.desal.2011.01.051Kaya, Y., Barlas, H., & Arayici, S. (2011). Evaluation of fouling mechanisms in the nanofiltration of solutions with high anionic and nonionic surfactant contents using a resistance-in-series model. Journal of Membrane Science, 367(1-2), 45-54. doi:10.1016/j.memsci.2010.10.037Delgado, S., Dı́az, F., Vera, L., Dı́az, R., & Elmaleh, S. (2004). Modelling hollow-fibre ultrafiltration of biologically treated wastewater with and without gas sparging. Journal of Membrane Science, 228(1), 55-63. doi:10.1016/j.memsci.2003.09.011Fan, L., Nguyen, T., Roddick, F. A., & Harris, J. L. (2008). Low-pressure membrane filtration of secondary effluent in water reuse: Pre-treatment for fouling reduction. Journal of Membrane Science, 320(1-2), 135-142. doi:10.1016/j.memsci.2008.03.058Xiao, D., Li, W., Chou, S., Wang, R., & Tang, C. Y. (2012). A modeling investigation on optimizing the design of forward osmosis hollow fiber modules. Journal of Membrane Science, 392-393, 76-87. doi:10.1016/j.memsci.2011.12.006Zator, M., Ferrando, M., López, F., & Güell, C. (2007). Membrane fouling characterization by confocal microscopy during filtration of BSA/dextran mixtures. Journal of Membrane Science, 301(1-2), 57-66. doi:10.1016/j.memsci.2007.05.038Nataraj, S., Schomäcker, R., Kraume, M., Mishra, I. M., & Drews, A. (2008). Analyses of polysaccharide fouling mechanisms during crossflow membrane filtration. Journal of Membrane Science, 308(1-2), 152-161. doi:10.1016/j.memsci.2007.09.060Nguyen, S. T., & Roddick, F. A. (2011). Chemical cleaning of ultrafiltration membrane fouled by an activated sludge effluent. Desalination and Water Treatment, 34(1-3), 94-99. doi:10.5004/dwt.2011.2790Xiao, K., Wang, X., Huang, X., Waite, T. D., & Wen, X. (2009). Analysis of polysaccharide, protein and humic acid retention by microfiltration membranes using Thomas’ dynamic adsorption model. Journal of Membrane Science, 342(1-2), 22-34. doi:10.1016/j.memsci.2009.06.016Hwang, K.-J., & Chiang, Y.-C. (2014). Comparisons of membrane fouling and separation efficiency in protein/polysaccharide cross-flow microfiltration using membranes with different morphologies. Separation and Purification Technology, 125, 74-82. doi:10.1016/j.seppur.2014.01.041Yamamura, H., Okimoto, K., Kimura, K., & Watanabe, Y. (2014). Hydrophilic fraction of natural organic matter causing irreversible fouling of microfiltration and ultrafiltration membranes. Water Research, 54, 123-136. doi:10.1016/j.watres.2014.01.024Nigam, M. O., Bansal, B., & Chen, X. D. (2008). Fouling and cleaning of whey protein concentrate fouled ultrafiltration membranes. Desalination, 218(1-3), 313-322. doi:10.1016/j.desal.2007.02.027MOUROUZIDISMOUROUZIS, S., & KARABELAS, A. (2006). Whey protein fouling of microfiltration ceramic membranes—Pressure effects. Journal of Membrane Science, 282(1-2), 124-132. doi:10.1016/j.memsci.2006.05.012Carić, M. Đ., Milanović, S. D., Krstić, D. M., & Tekić, M. N. (2000). Fouling of inorganic membranes by adsorption of whey proteins. Journal of Membrane Science, 165(1), 83-88. doi:10.1016/s0376-7388(99)00221-5Tasselli, F., Cassano, A., & Drioli, E. (2007). Ultrafiltration of kiwifruit juice using modified poly(ether ether ketone) hollow fibre membranes. Separation and Purification Technology, 57(1), 94-102. doi:10.1016/j.seppur.2007.03.007Vincent-Vela, M.-C., Álvarez-Blanco, S., Lora-García, J., & Bergantiños-Rodríguez, E. (2009). Estimation of the gel layer concentration in ultrafiltration: Comparison of different methods. Desalination and Water Treatment, 3(1-3), 157-161. doi:10.5004/dwt.2009.454Valiño, V., San Román, M. F., Ibáñez, R., Benito, J. M., Escudero, I., & Ortiz, I. (2014). Accurate determination of key surface properties that determine the efficient separation of bovine milk BSA and LF proteins. Separation and Purification Technology, 135, 145-157. doi:10.1016/j.seppur.2014.07.051Luck, P. J., Vardhanabhuti, B., Yong, Y. H., Laundon, T., Barbano, D. M., & Foegeding, E. A. (2013). Comparison of functional properties of 34% and 80% whey protein and milk serum protein concentrates. Journal of Dairy Science, 96(9), 5522-5531. doi:10.3168/jds.2013-6617Marcos, B., Moresoli, C., Skorepova, J., & Vaughan, B. (2009). CFD modeling of a transient hollow fiber ultrafiltration system for protein concentration. Journal of Membrane Science, 337(1-2), 136-144. doi:10.1016/j.memsci.2009.03.036Chung, T.-S., Qin, J.-J., & Gu, J. (2000). Effect of shear rate within the spinneret on morphology, separation performance and mechanical properties of ultrafiltration polyethersulfone hollow fiber membranes. Chemical Engineering Science, 55(6), 1077-1091. doi:10.1016/s0009-2509(99)00371-1Salahi, A., Mohammadi, T., Rahmat Pour, A., & Rekabdar, F. (2009). Oily wastewater treatment using ultrafiltration. Desalination and Water Treatment, 6(1-3), 289-298. doi:10.5004/dwt.2009.480Janssen, A. N., van Agtmaal, J., van den Broek, W. B. P., de Koning, J., Menkveld, H. W. H., Schrotter, J.-C., … van der Graaf, J. H. J. M. (2008). Monitoring of SUR to control and enhance the performance of dead-end ultrafiltration installations treating wwtp effluent. Desalination, 231(1-3), 99-107. doi:10.1016/j.desal.2007.10.024Torà-Grau, M., Soler-Cabezas, J. L., Vincent-Vela, M. C., Mendoza-Roca, J. A., & Martínez-Francisco, F. J. (2014). Comparison of different model solutions to simulate membrane fouling in the ultrafiltration of a secondary effluent from a municipal wastewater treatment plant. Desalination and Water Treatment, 1-7. doi:10.1080/19443994.2014.93986

Ultrafiltration of municipal wastewater: study on fouling models and fouling mechanisms

Ultrafiltration (UF) with hollow fiber membranes is a proven membrane technique that can achieve high water quality standards as a tertiary treatment in municipal wastewater treatment plants. However, UF has a major drawback, membrane fouling, which causes losses of productivity and increases operation costs. Thus, the aim of this work is to model membrane fouling in the UF of a secondary treatment effluent. The tests were carried out with a model wastewater solution that consisted of bovine serum albumin and dextran. Three different transmembrane pressures and three different crossflow velocities were tested. Several fouling models available in the literature, and new models proposed, were fitted to permeate flux decline experimental data. The models studied by other authors and considered in this study were: Hermia s models (complete, intermediate, standard pore blocking and gel layer) and Belfort s model. The new models proposed in this work were: modified Belfort s model, quadratic exponential model, logarithmic inversed model, double exponential model and tangent inversed model. The fitting accuracy of the models was determined in terms of the R-squared and standard deviation. The results showed that the model that had the higher fitting accuracy was the logarithmic inversed model. Among the Hermia s models, the model that had the higher fitting accuracy was the intermediate pore blocking model. Therefore, the predominant fouling mechanism was determined and it was the intermediate pore blocking modelThe authors wish to gratefully acknowledge the financial support of the Generalitat Valenciana through the project "Ayudas para la realizacion de proyectos I+D para grupos de investigacion emergentes GV/2013".Soler Cabezas, JL.; Tora Grau, M.; Vincent Vela, MC.; Mendoza Roca, JA.; Martínez Francisco, FJ. (2014). Ultrafiltration of municipal wastewater: study on fouling models and fouling mechanisms. Desalination and Water Treatment. 1-11. doi:10.1080/19443994.2014.969320S111Gadani, V., Irwin, R., & Mandra, V. (1996). Ultrafiltration as a tertiary treatment: Joint research program on membranes. Desalination, 106(1-3), 47-53. doi:10.1016/s0011-9164(96)00091-4Illueca-Muñoz, J., Mendoza-Roca, J. A., Iborra-Clar, A., Bes-Piá, A., Fajardo-Montañana, V., Martínez-Francisco, F. J., & Bernácer-Bonora, I. (2008). Study of different alternatives of tertiary treatments for wastewater reclamation to optimize the water quality for irrigation reuse. Desalination, 222(1-3), 222-229. doi:10.1016/j.desal.2007.01.157Muthukumaran, S., Jegatheesan, J. V., & Baskaran, K. (2013). Comparison of fouling mechanisms in low-pressure membrane (MF/UF) filtration of secondary effluent. Desalination and Water Treatment, 52(4-6), 650-662. doi:10.1080/19443994.2013.826324Delgado, S., Dı́az, F., Vera, L., Dı́az, R., & Elmaleh, S. (2004). Modelling hollow-fibre ultrafiltration of biologically treated wastewater with and without gas sparging. Journal of Membrane Science, 228(1), 55-63. doi:10.1016/j.memsci.2003.09.011Qin, J.-J., Oo, M. H., Lee, H., & Kolkman, R. (2004). Dead-end ultrafiltration for pretreatment of RO in reclamation of municipal wastewater effluent. Journal of Membrane Science, 243(1-2), 107-113. doi:10.1016/j.memsci.2004.06.010Konieczny, K. (1998). Disinfection of surface and ground waters with polymeric ultrafiltration membranes. Desalination, 119(1-3), 251-258. doi:10.1016/s0011-9164(98)00166-0Madaeni, S. S., Fane, A. G., & Grohmann, G. S. (1995). Virus removal from water and wastewater using membranes. Journal of Membrane Science, 102, 65-75. doi:10.1016/0376-7388(94)00252-tArnal Arnal, J. M., Sancho Fernández, M., Martín Verdú, G., & Lora García, J. (2001). Design of a membrane facility for water potabilization and its application to Third World countries. Desalination, 137(1-3), 63-69. doi:10.1016/s0011-9164(01)00205-3Arévalo, J., Garralón, G., Plaza, F., Moreno, B., Pérez, J., & Gómez, M. Á. (2009). Wastewater reuse after treatment by tertiary ultrafiltration and a membrane bioreactor (MBR): a comparative study. Desalination, 243(1-3), 32-41. doi:10.1016/j.desal.2008.04.013Katsoufidou, K., Yiantsios, S. G., & Karabelas, A. J. (2008). An experimental study of UF membrane fouling by humic acid and sodium alginate solutions: the effect of backwashing on flux recovery. Desalination, 220(1-3), 214-227. doi:10.1016/j.desal.2007.02.038Muthukumaran, S., Nguyen, D. A., & Baskaran, K. (2011). Performance evaluation of different ultrafiltration membranes for the reclamation and reuse of secondary effluent. Desalination, 279(1-3), 383-389. doi:10.1016/j.desal.2011.06.040Henderson, R. K., Subhi, N., Antony, A., Khan, S. J., Murphy, K. 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Advanced glycation end products as a biomarker for incisional hernia

Background: Incisional hernia is one of the most frequent complications after abdominal surgery, with incidences up to 30%. A reliable biomarker for the prediction of this complication is lacking. Advanced glycosylation end products (AGEs), also known as non-enzymatic collagen crosslinks, are correlated with aging, smoking, hyperglycemia, hyperlipidemia and oxidative stress. In this study the accumulation of AGEs and the relation between AGEs and incisional hernia were investigated. Materials and methods: In an explorato

Improvement of non-invasive tests of liver steatosis and fibrosis as indicators for non-alcoholic fatty liver disease in type 2 diabetes mellitus patients with elevated cardiovascular risk profile using the PPAR-alpha/gamma agonist aleglitazar

Background: Peroxisome proliferator-activated receptor (PPAR) agonists may have favorable outcomes on non-alcoholic fatty liver disease. This study serves as proof of concept to evaluate whether dual PPAR-alpha/gamma agonists improve non-invasive tests of liver steatosis and fibrosis. Methods: This is a post-hoc analysis of a randomized, double-blind, placebo-controlled, multi-center trial comprising 7226 patients with type 2 diabetes mellitus and recent coronary artery disease randomized to receive aleglitazar, a PPAR-alpha/gamma agonists, or placebo for two years. Main outcomes were change in non-invasive tests for liver steatosis and fibrosis: Liver Fat Score (LFS), Liver Accumulation Product (LAP), Fibrosis-4 (FIB-4), and NAFLD Fibrosis Score (NFS). Results: LFS, LAP and FIB-4 decreased upon treatment, whereas scores in the placebo group remained the same or increased (PCellular mechanisms in basic and clinical gastroenterology and hepatolog

Grading the loss of sensation in diabetic patients: A psychometric evaluation of the Rotterdam diabetic foot study test battery

Introduction: Static- and moving 2-point discrimination (S2PD, M2PD), 10-g monofilaments- and tuning fork are validated outcome measures of clinical manifestations of diabetes-related neuropathy. No modern statistical techniques have been us

Use of the osmotic membrane bioreactor for the management of tannery wastewater using absorption liquid waste as draw solution

[EN] The performance of an osmotic membrane bioreactor (OMBR) for treating tannery wastewater at laboratory scale has been evaluated in this study. The forward osmosis (FO) membrane tested was CTA-NW from HTI. As draw solution, actual waste water from an absorption column for ammonia separation, which consists mainly of ammonium sulphate was used. The study was focused on the salt reverse flux during the OMBR operation, membrane water flux, biomass characteristics and membrane fouling. Regarding membrane water flux change with the time, the measured values diminished from 3.44 to 0.72 LMH due to the membrane fouling and the salt accumulation in the biological reactor. The stable mixed liquor conductivity value at the end of the experiment was 29.8 mS·cm¿1. The chemical oxygen demand (COD) removal efficiencies were maintained near 80% until the first 50 days of operation, considering the soluble COD in the reactor instead of the COD in the membrane permeate for the performance calculation. Thence, COD removal efficiencies decreased progressively due to the accumulation of non degradable COD coming from the tannery wastewater. Concerning to the membrane fouling, FESEM/EDX analysis corroborated that organic fouling was predominant on the membrane active layer.This study was supported by the Spanish Ministry of Economy and Competitiveness through the project RTC-2015-3582-5-AR.Lujan Facundo, MJ.; Mendoza Roca, JA.; Soler Cabezas, JL.; Bes-Piá, M.; Vincent Vela, MC.; Pastor Alcañiz, L. (2019). Use of the osmotic membrane bioreactor for the management of tannery wastewater using absorption liquid waste as draw solution. Process Safety and Environmental Protection. 131:292-299. https://doi.org/10.1016/j.psep.2019.09.024S29229913

A placebo-controlled proof-of-concept study of alirocumab on postprandial lipids and vascular elasticity in insulin-treated patients with type 2 diabetes mellitus

Aim: Type 2 diabetes mellitus (T2DM) is associated with an increased risk of cardiovascular disease (CVD) linked to atherogenic dyslipidaemia and postprandial hyperlipidaemia. Alirocumab, a proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor, improves CVD risk by reducing the concentration of low-density lipoprotein-cholesterol (LDL-C). However, effects of PCK9 inhibitors on other aspects of diabetic dyslipidaemia, particularly in the postprandial situation, are less clear. Material and Methods: Twelve male patients with T2DM on an intensive insulin regimen completed a 6-week randomized, double-blind, placebo-controlled, proof-of-concept study. Participants received three biweekly dosages of subcutaneous alirocumab (150 mg) or placebo. Before and after the intervention, fasting and postprandial triglyceride (TG) plasma levels, apolipoprotein (apo) B48, lipoprotein composition isolated by ultracentrifugation, vascular function and markers of inflammation were evaluated. Results: Alirocumab treatment reduced fasting plasma TG levels (between group median change −24.7%; P = 0.018) and fasting apoB48 serum levels (−35.9%; P = 0.039) compared with placebo. Alirocumab reduced the plasma TG area under the curve (AUC) (−26.4%; P = 0.006) and apoB48 AUC (−55.7%; P = 0.046), as well as plasma TG incremental AUC (−21.4%; P = 0.04) and apoB48 incremental AUC (−26.8%; P = 0.02). In addition, alirocumab reduced fasting and postprandial TG levels in very low-density lipoprotein (VLDL) and LDL. Alirocumab improved fasting pulse wave velocity, but no changes in postprandial markers of inflammation were observed. Conclusions: In addition to the well-known LDL-C-reducing effects, 6 weeks of alirocumab treatment lowered both fasting and postprandial plasma TG levels by reducing the TG levels in VLDL and LDL and the concentration of intestinal remnants