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1
Peiris, R. H., H. Budman, R. L. Legge e C. Moresoli. "Assessing irreversible fouling behavior of membrane foulants in the ultrafiltration of natural water using principal component analysis of fluorescence excitation-emission matrices". Water Supply 11, n. 2 (1 aprile 2011): 179–85. http://dx.doi.org/10.2166/ws.2011.025.
Testo completoAbstract (sommario):
Natural river water is comprised of different foulant components such as natural organic matter and colloidal/particulate matter. Both individual and combined contributions of these foulant components results in different fouling behaviour. The ability to characterize these contributions that lead to reversible and irreversible membrane fouling would be beneficial for the implementation of fouling monitoring and control strategies for membrane-based drinking water treatment operations. A fluorescence excitation-emission matrix and principal component analysis-based approach was able to qualitatively estimate the accumulation of humic substances (HS)-, protein- and colloidal/particulate matter-like foulant components in membranes during the ultrafiltration (UF) of natural river water. A bench-scale flat sheet UF cross-flow set-up and successive permeation and membrane backwashing cycles were used. Analysis of the accumulation of these foulant components revealed that the increased levels of colloidal/particulate matter accumulation in the membranes appeared to have increased the extent of irreversible fouling by HS-like matter whereas lower irreversible fouling by protein-like matter was observed with increased colloidal/particulate matter accumulation. The results also indicate that the combined contributions by these foulants are important in the fouling of membranes during the UF of river water.
2
Yan, Linlin, Ruixue Li, Yu Song, Yanping Jia, Zheng Li, Lianfa Song e Haifeng Zhang. "Characterization of the Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Evolution of the Foulants’ Composition and Aggregation Ability". Membranes 9, n. 7 (16 luglio 2019): 85. http://dx.doi.org/10.3390/membranes9070085.
Testo completoAbstract (sommario):
In this study, the characteristics of membrane foulants were analyzed with regard to morphology, composition, and aggregation ability during the three stages of transmembrane pressure (TMP) development (fast–slow–fast rise in TMP) in a steady operational membrane bioreactor (MBR). The results obtained show that the fouling layer at the slow TMP-increase stage possessed a higher average roughness (71.27 nm) and increased fractal dimension (2.33), which resulted in a low membrane fouling rate (0.87 kPa/d). A higher extracellular DNA (eDNA) proportion (26.12%) in the extracellular polymeric substances (EPS) resulted in both higher zeta potential (-23.3 mV) and higher hydrophobicity (82.3%) for initial foulants, which induced and increased the protein proportion in the subsequent fouling layer (74.11%). Furthermore, the main composition of the EPS shifted from protein toward polysaccharide dominance in the final fouling layer. The aggregation test confirmed that eDNA was essential for foulant aggregation in the initial fouling layer, whereas ion interaction significantly affected foulant aggregation in the final fouling layer.
3
Chen, Yian, Montserrat Rovira-Bru, Francesc Giralt e Yoram Cohen. "Hydraulic Resistance and Protein Fouling Resistance of a Zirconia Membrane with a Tethered PVP Layer". Water 13, n. 7 (31 marzo 2021): 951. http://dx.doi.org/10.3390/w13070951.
Testo completoAbstract (sommario):
The influence of surface modification of zirconia (ZrO2) membrane with tethered poly(vinyl pyrrolidone) (PVP) chains was evaluated with respect to the impact of pH and ionic strength on hydraulic resistance and fouling resistance in the filtration of bovine serum albumin (BSA) and lysozyme (Lys) as model protein foulants. The tethered PVP surface layer led to membrane permeability and fouling propensity that were responsive to both pH and ionic strength. The PVP-modified membrane (PVP-ZrO2) hydraulic resistance increased by up to ~48% over a pH range of 6–11, but with no discernible impact at lower pH. Membrane hydraulic resistance was virtually unaffected by ionic strength over the 0.001–1 M range. However, reversible foulant cake resistance in BSA and Lys solution filtration increased with elevated ionic strength, owing in part to the weakening of protein–protein repulsion. Irreversible BSA and Lys fouling was affected by the operational pH relative to the protein isoelectric point (IEP) and reduced under conditions of chain swelling. Irreversible membrane fouling resistance for both proteins was significantly lower, by ~11–49% and 18–74%, respectively, for the PVP-ZrO2 membrane relative to the unmodified ZrO2 membrane. The present results suggest the merit of further exploration of fouling reduction and improvement of membrane cleaning effectiveness via tuning pH and ionic strength triggered conformational responsiveness of the tethered target polymer layer.
4
Sun, Chunyi, Na Zhang, Fazhan Li, Guoyi Ke, Lianfa Song, Xiaoqian Liu e Shuang Liang. "Quantitative Analysis of Membrane Fouling Mechanisms Involved in Microfiltration of Humic Acid–Protein Mixtures at Different Solution Conditions". Water 10, n. 10 (22 settembre 2018): 1306. http://dx.doi.org/10.3390/w10101306.
Testo completoAbstract (sommario):
A systematical quantitative understanding of different mechanisms, though of fundamental importance for better fouling control, is still unavailable for the microfiltration (MF) of humic acid (HA) and protein mixtures. Based on extended Derjaguin–Landau–Verwey–Overbeek (xDLVO) theory, the major fouling mechanisms, i.e., Lifshitz–van der Waals (LW), electrostatic (EL), and acid–base (AB) interactions, were for the first time quantitatively analyzed for model HA–bovine serum albumin (BSA) mixtures at different solution conditions. Results indicated that the pH, ionic strength, and calcium ion concentration of the solution significantly affected the physicochemical properties and the interaction energy between the polyethersulfone (PES) membrane and HA–BSA mixtures. The free energy of cohesion of the HA–BSA mixtures was minimum at pH = 3.0, ionic strength = 100 mM, and c(Ca2+) = 1.0 mM. The AB interaction energy was a key contributor to the total interaction energy when the separation distance between the membrane surface and HA–BSA mixtures was less than 3 nm, while the influence of EL interaction energy was of less importance to the total interaction energy. The attractive interaction energies of membrane–foulant and foulant–foulant increased at low pH, high ionic strength, and calcium ion concentration, thus aggravating membrane fouling, which was supported by the fouling experimental results. The obtained findings would provide valuable insights for the quantitative understanding of membrane fouling mechanisms of mixed organics during MF.
5
Scudeller, Luisa A., Pascal Blanpain-Avet, Thierry Six, Séverine Bellayer, Maude Jimenez, Thomas Croguennec, Christophe André e Guillaume Delaplace. "Calcium Chelation by Phosphate Ions and Its Influence on Fouling Mechanisms of Whey Protein Solutions in a Plate Heat Exchanger". Foods 10, n. 2 (27 gennaio 2021): 259. http://dx.doi.org/10.3390/foods10020259.
Testo completoAbstract (sommario):
Fouling of plate heat exchangers (PHEs) is a recurring problem when pasteurizing whey protein solutions. As Ca2+ is involved in denaturation/aggregation mechanisms of whey proteins, the use of calcium chelators seems to be a way to reduce the fouling of PHEs. Unfortunately, in depth studies investigating the changes of the whey protein fouling mechanism in the presence of calcium chelators are scarce. To improve our knowledge, reconstituted whey protein isolate (WPI) solutions were prepared with increasing amounts of phosphate, expressed in phosphorus (P). The fouling experiments were performed on a pilot-scale PHE, while monitoring the evolution of the pressure drop and heat transfer coefficient. The final deposit mass distribution and structure of the fouling layers were investigated, as well as the whey protein denaturation kinetics. Results suggest the existence of two different fouling mechanisms taking place, depending on the added P concentration in WPI solutions. For added P concentrations lower or equal to 20 mg/L, a spongy fouling layer consists of unfolded protein strands bound by available Ca2+. When the added P concentration is higher than 20 mg/L, a heterogeneously distributed fouling layer formed of calcium phosphate clusters covered by proteins in an arborescence structure is observed.
6
Miyoshi, Taro, Yuhei Nagai, Tomoyasu Aizawa, Katsuki Kimura e Yoshimasa Watanabe. "Proteins causing membrane fouling in membrane bioreactors". Water Science and Technology 72, n. 6 (2 giugno 2015): 844–49. http://dx.doi.org/10.2166/wst.2015.282.
Testo completoAbstract (sommario):
In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.
7
Buchori, Luqman, Heru Susanto e Budiyono Budiyono. "SINTESIS MEMBRAN ULTRAFILTRASI NON FOULING UNTUK APLIKASI PEMPROSESAN BAHAN PANGAN". Reaktor 13, n. 1 (3 febbraio 2010): 10. http://dx.doi.org/10.14710/reaktor.13.1.10-15.
Testo completoAbstract (sommario):
Membran ultrafiltrasi (UF) telah terbukti sebagai proses yang menjanjikan untuk aplikasi di bidang pemprosesan bahan pangan. Namun, peristiwa fouling dapat menurunkan kinerja membran secara signifikan. Meskipun banyak metode pengendalian fouling telah diusulkan, dalam banyak kasus kinerja proses sangat dipengaruhi oleh membran sebagai jantung dari proses. Dalam makalah ini pengendalian fouling dilakukan dengan memodifikasi permukaan membran dengan teknik kopolimerisasi foto-grafting. Acrylic acid (AA), acrylamido methylpropane sulfonic acid (AMPS), poly(ethylene glycol) methacrylate (PEGMA), dan N,N-dimethyl-N-(2-methacryloyloxyethyl-N-(3sulfopropyl)ammonium betaine sebagai senyawa zwitterion (ZI) digunakan sebagai monomer fungsional. Pengaruh waktu iradiasi terhadap efektifitas modifikasi telah diamati. Kinerja membran hasil modifikasi kemudian diuji dengan menggunakan berbagai model larutan foulant yang meliputi larutan protein, larutan polisakarida dan larutan polifenol. Hasil penelitian menunjukkan bahwa sifat non fouling membran sangat jelas dapat ditingkatkan baik dengan PEGMA maupun dengan ZI. Secara umum, modifikasi menggunakan PEGMA menunjukkan kinerja yang lebih baik. Larutan polifenol menunjukkan karakter foulant yang paling kuat diantara model foulant.
8
Berg, Thilo H. A., Jes C. Knudsen, Richard Ipsen, Frans van den Berg, Hans H. Holst e Alexander Tolkach. "Investigation of Consecutive Fouling and Cleaning Cycles of Ultrafiltration Membranes Used for Whey Processing". International Journal of Food Engineering 10, n. 3 (1 settembre 2014): 367–81. http://dx.doi.org/10.1515/ijfe-2014-0028.
Testo completoAbstract (sommario):
Abstract Development of resistance during multiple foulings and three-step Cleaning-In-Place (CIP) operations, simulating an industrial cleaning regime of polysulfone ultrafiltration membranes, was investigated. The study explored how trans-membrane pressure (150 and 300 kPa) and feed protein concentration (0.9 and 10%) influenced resistance reduction during filtration and flux recovery by the cleaning procedures. New membranes, pre-cleaned with a full CIP cycle, were used for each experiment. Subsequent fouling (simulating production) and CIP were done three times in a row and the development of fouling layer resistance was monitored and evaluated. Results show that filtration performance decreased during the first days of usage, possibly related to build-up of internal fouling. Cleaning success based on flux recovery was negatively influenced by a high protein concentration in the feed, but independent of the trans-membrane pressure during filtration.
9
Peiris, R. H., M. Jaklewicz, H. Budman, R. L. Legge e C. Moresoli. "Characterization of hydraulically reversible and irreversible fouling species in ultrafiltration drinking water treatment systems using fluorescence EEM and LC–OCD measurements". Water Supply 13, n. 5 (1 settembre 2013): 1220–27. http://dx.doi.org/10.2166/ws.2013.130.
Testo completoAbstract (sommario):
The application of the fluorescence excitation-emission matrix (EEM) approach and liquid chromatography–organic carbon detection (LC–OCD) analysis for the characterization of hydraulically reversible and irreversible fouling species, extracted from hollow fiber ultrafiltration (UF) membranes used in drinking water treatment, was demonstrated. Hydraulically reversible and irreversible fouling species were extracted from two pilot UF membrane systems operated in parallel with lake water as the feed. Two membrane cleaning protocols, hydraulic- and chemical-based (NaOCl and citric acid) cleaning, were considered. Colloidal/particulate matter together with protein-like and metal species in water appeared to contribute to the formation of a hydraulically removable fouling layer on the membranes. Hydraulically irreversible fouling, in contrast, was impacted considerably by humic substances (HS) and protein-like matter. The formation of an irreversible fouling layer was also likely influenced by interactions between the colloidal/particulate matter and metal species together with HS and protein-like matter. LC–OCD analysis revealed the presence of predominant levels of lower molecular weight HS-like matter – compared to the HS-like matter commonly present in lake water – in the citric acid extracted foulant fraction. The permeability loss due to hydraulically irreversible UF fouling was considerably greater than the permeability loss due to hydraulically reversible UF fouling. A permanent permeability loss (∼25–35% of the initial permeability) was present even after the application of considerably strong chemical cleaning protocols on both pilot systems. This study indicated that the fluorescence EEM approach can be applied for monitoring and characterization of membrane cleaning procedures and as a potential diagnostic tool for assessing the effectiveness of hydraulic- and chemical-based cleaning protocols employed in UF drinking water treatment operations using rapid off-line measurements. On the other hand, since the LC–OCD analysis technique is a comparatively time consuming method, it may be used for verification of the fluorescence EEM-based results of the foulant fractions.
10
Chaipetch, Wiparat, Arisa Jaiyu, Panitan Jutaporn, Marc Heran e Watsa Khongnakorn. "Fouling Behavior in a High-Rate Anaerobic Submerged Membrane Bioreactor (AnMBR) for Palm Oil Mill Effluent (POME) Treatment". Membranes 11, n. 9 (25 agosto 2021): 649. http://dx.doi.org/10.3390/membranes11090649.
Testo completoAbstract (sommario):
The characteristics of foulant in the cake layer and bulk suspended solids of a 10 L submerged anaerobic membrane bioreactor (AnMBR) used for treatment of palm oil mill effluent (POME) were investigated in this study. Three different organic loading rates (OLRs) were applied with prolonged sludge retention time throughout a long operation time (270 days). The organic foulant was characterized by biomass concentration and concentration of extracellular polymeric substances (EPS). The thicknesses of the cake layer and foulant were analyzed by confocal laser scanning microscopy and Fourier transform infrared spectroscopy. The membrane morphology and inorganic elements were analyzed by field emission scanning electron microscope coupled with energy dispersive X-ray spectrometer. Roughness of membrane was analyzed by atomic force microscopy. The results showed that the formation and accumulation of protein EPS in the cake layer was the key contributor to most of the fouling. The transmembrane pressure evolution showed that attachment, adsorption, and entrapment of protein EPS occurred in the membrane pores. In addition, the hydrophilic charge of proteins and polysaccharides influenced the adsorption mechanism. The composition of the feed (including hydroxyl group and fatty acid compounds) and microbial metabolic products (protein) significantly affected membrane fouling in the high-rate operation.
11
Che, Sanchuan, Muyi Ye, Kayiu Li, Yang Xie, Pengyou Du e Hunan Deng. "A review of bio-inspired fouling resistance surfaces". Applied and Computational Engineering 7, n. 1 (21 luglio 2023): 478–506. http://dx.doi.org/10.54254/2755-2721/7/20230409.
Testo completoAbstract (sommario):
Solid fouling settlement, defined as the unexpected payment of various types of solid contaminants, including ice, wax, bacteria, and protein, can result in many problems in daily life and production and cause economic and security losses. Despite many traditional methods for reducing foulant to make a more durable and efficient antifouling surface, many artificial surfaces inspired by the natural antifouling material which the environment has selected during the process of evolution, including lotus leaf, pilot whale skin, gecko feet, shark skin, and pitcher plant are developed to resist adhesion of multiple foulants in an efficient and environmentally friendly way. In this review, the mechanism of how surfaces using patterns similar to the natural antifouling surface resist fouling materials is overviewed. Various methods for fouling formation classify the hazard, properties, and characteristics of different fouling materials. The approaches typically applied in designing a surface with high fouling resistance are presented first. After interpreting the theories and models mentioned in the explanation of the fouling resistance property, the textural microstructures, the chemical and physical properties used, and applications for fouling resistance of several bio-inspired fouling resistance surfaces, and how these surfaces can be improved in the future are discussed.
12
Daufin, Georges, Françoise Michel, Jean-Pierre Labbé, Auguste Quemebais e André Grangeon. "Ultrafiltration of defatted whey: improving performance by limiting membrane fouling". Journal of Dairy Research 60, n. 1 (febbraio 1993): 79–88. http://dx.doi.org/10.1017/s0022029900027369.
Testo completoAbstract (sommario):
SummaryDefatted whey was obtained by aggregating residual fat to calcium phosphate precipitates and separating the precipitate by membrane microfiltration (pore diameter 0·2 μm). When ultrafiltering this defatted whey the performance of an inorganic membrane (molecular mass cut-off, 10 kDa) was limited by the large concentration of Ca and phosphates. Consequently, the influence of the aggregation pH (either decreasing or constant) on membrane fouling has been studied for ultrafiltration (UF) of defatted sweet whey and defatted whey UF retentates (protein content up to 30g l–1). In all experiments protein rejection was 100%. When pH was kept constant during the pretreatment, membrane fouling was significantly lowered. Hydraulic resistances ascribed to irreversible fouling were in good agreement with fouled membrane analyses performed by i.r. and X-ray photoelectron spectroscopies. They showed that provided a low Ca and phosphate content was maintained in the microfiltrate, which was achieved at constant pH, no apatite was detected within the membrane, and proteins were less fouling. On the other hand, the amount of fouling material depended on the transmembrane pressure gradient along the hydraulic path. On the membrane surface, the higher the pressure, the higher the fouling. In the membrane bulk, the fouling heterogeneity depended on the ability of the defatted whey to precipitate apatite. If it did, the higher the pressure, the higher the calcium phosphate and the protein fouling. With other phosphate structures, the bulk fouling depended on the barrier formed by surface fouling layers and the protein concentration polarization layer, which were more resistant to solute and solvent transfer under higher pressure, where they were thicker.
13
Nichka, Vladlen S., Thibaud R. Geoffroy, Victor Nikonenko e Laurent Bazinet. "Impacts of Flow Rate and Pulsed Electric Field Current Mode on Protein Fouling Formation during Bipolar Membrane Electroacidification of Skim Milk". Membranes 10, n. 9 (26 agosto 2020): 200. http://dx.doi.org/10.3390/membranes10090200.
Testo completoAbstract (sommario):
Fouling is one of the major problems in electrodialysis. The aim of the present work was to investigate the effect of five different solution flow rates (corresponding to Reynolds numbers of 162, 242, 323, 404 and 485) combined with the use of pulsed electric field (PEF) current mode on protein fouling of bipolar membrane (BPM) during electrodialysis with bipolar membranes (EDBM) of skim milk. The application of PEF prevented the fouling formation by proteins on the cationic interface of the BPM almost completely, regardless of the flow rate or Reynolds number. Indeed, under PEF mode of current the weight of protein fouling was negligible in comparison with CC current mode (0.07 ± 0.08 mg/cm2 versus 5.56 ± 2.40 mg/cm2). When a continuous current (CC) mode was applied, Reynolds number equals or higher than 323 corresponded to a minimal value of protein fouling of BPM. This positive effect of both increasing the flow rate and using PEF is due to the facts that during pauses, the solution flow flushes the accumulated protein from the membrane while in the same time there is a decrease in concentration polarization (CP) and consequently decrease in H+ generation at the cationic interface of the BPM, minimizing fouling formation and accumulation.
14
Alpiger, Simone Bleibach, Chloé Solet, Tem Thi Dang e Milena Corredig. "Ultrafiltration of Rapeseed Protein Concentrate: Effect of Pectinase Treatment on Membrane Fouling". Foods 13, n. 15 (31 luglio 2024): 2423. http://dx.doi.org/10.3390/foods13152423.
Testo completoAbstract (sommario):
Membrane filtration technologies have shown great potential as a gentle and effective method for concentrating and fractionating proteins for food applications. However, the application of this technology to plant-derived protein streams is in its infancy. In this study, an aqueous rapeseed protein concentrate was obtained with wet milling, and its performance during ultrafiltration with two distinct molecular weight cut-offs (10 and 100 kDa) was tested. All rapeseed proteins were retained during filtration. The addition of pectinase during extraction prior to filtration caused important structural modifications to the extract, resulting in increased permeate fluxes, increased carbohydrate permeation and a reduction in irreversible fouling. Lager pore sizes led to more pronounced fouling. FTIR analysis of the spent membranes showed that proteins and lipids are causing irreversible fouling.
15
Isma M. I., Aida, Munira Mohammad, Putri Razreena Abdul Razak, Hazmin Mansor, A. Idris e Siti Baizura M. "Surface morphology of biofouling in membrane bioreactor treating actual sewage". Journal of Biological Studies 5, n. 3 (21 settembre 2022): 353–62. http://dx.doi.org/10.62400/jbs.v5i3.7041.
Testo completoAbstract (sommario):
Biofouling is the most challenging operational problem in membrane bioreactors. The goal of this study is to evaluate the foulants mechanism by profiling the foulants morphology in a membrane bioreactor treating actual sewage. A 10 m2 hollow fiber membrane was set up at MLSS of 9 g/L and HRT of 8 hours. CLSM and FESEM were used to characterize the membrane morphologies. The trans-membrane pressure was monitored, and membrane samples were analysed on weekly basis. The performance of the membrane bioreactor treating the actual sewage showed a remarkable result. The biofilm and cake layer formation dominated the majority of fouling in the MBR operation, resulting in slower permeation flux decay over time. The evaluation of fouling layers and the mechanism of biofouling development through profiling of foulant morphology using FESEM and CLSM revealed that the membrane experienced mild internal pore-clogging, implying that fouling occurred mainly on the membrane surface. The fluorescent staining of CLSM images revealed that proteins, -D-glucopyranose polysaccharides, and lipids were aggregated into clusters with protein depth thickness recorded at 22 μm. FESEM images revealed that the membrane experienced mild internal pore-clogging and had marginally reduced the overall water permeability and severely reduced the mass transfer coefficient. It can be concluded that proteins and microbial cells were the primary constituents of the fouling layer which may have contributed to the membrane performance deterioration after fouling.
16
Gao, Kuo, Hong Yang, Haichen Liu e Bingzhi Dong. "Alleviating Ultrafiltration Membrane Fouling Caused by Effluent Organic Matter Using Pre-Ozonation: A Perspective of EEM and Molecular Weight Distribution". Membranes 13, n. 4 (21 aprile 2023): 452. http://dx.doi.org/10.3390/membranes13040452.
Testo completoAbstract (sommario):
Wastewater reclamation has gradually become an important way to cope with the global water crisis. Ultrafiltration plays an imperative part as a safeguard for the aim but is often limited by membrane fouling. Effluent organic matter (EfOM) has been known to be a major foulant during ultrafiltration. Hence, the primary aim of this study was to investigate the effects of pre-ozonation on the membrane fouling caused by EfOM in secondary wastewater effluents. In addition, the physicochemical property changes of EfOM during pre-ozonation and the subsequent influence on membrane fouling were systemically investigated. The combined fouling model and the morphology of fouled membrane were adopted to scrutinize the fouling alleviation mechanism by pre-ozonation. It was found that membrane fouling by EfOM was dominated by hydraulically reversible fouling. In addition, an obvious fouling reduction was achieved by pre-ozonation with 1.0 mg O3/mg DOC. The resistance results showed that the normalized hydraulically reversible resistance was reduced by ~60%. The water quality analysis indicated that ozone degraded high molecular weight organics such as microbial metabolites and aromatic protein and medium molecular weight organics (humic acid-like) into smaller fractions and formed a looser fouling layer on the membrane surface. Furthermore, pre-ozonation made the cake layer foul towards pore blocking, thereby reducing fouling. In addition, there was a little degradation in the pollutant removal performance with pre-ozonation. The DOC removal rate decreased by more than 18%, while UV254 decreased by more than 20%.
17
Xu, Hao, Kang Xiao, Jinlan Yu, Bin Huang, Xiaomao Wang, Shuai Liang, Chunhai Wei, Xianghua Wen e Xia Huang. "A Simple Method to Identify the Dominant Fouling Mechanisms during Membrane Filtration Based on Piecewise Multiple Linear Regression". Membranes 10, n. 8 (29 luglio 2020): 171. http://dx.doi.org/10.3390/membranes10080171.
Testo completoAbstract (sommario):
Membrane fouling is a complicated issue in microfiltration and ultrafiltration. Clearly identifying the dominant fouling mechanisms during the filtration process is of great significance for the phased and targeted control of fouling. To this end, we propose a semi-empirical multiple linear regression model to describe flux decline, incorporating the five fouling mechanisms (the first and second kinds of standard blocking, complete blocking, intermediate blocking, and cake filtration) based on the additivity of the permeate volume contributed by different coexisting mechanisms. A piecewise fitting protocol was established to distinguish the fouling stages and find the significant mechanisms in each stage. This approach was applied to a case study of a microfiltration membrane filtering a model foulant solution composed of polysaccharide, protein, and humic substances, and the model fitting unequivocally revealed that the dominant fouling mechanism evolved in the sequence of initial adaptation, fast adsorption followed by slow adsorption inside the membrane pores, and the gradual growth of a cake/gel layer on the membrane surface. The results were in good agreement with the permeate properties (total organic carbon, ultraviolet absorbance, and fluorescence) during the filtration process. This modeling approach proves to be simple and reliable for identifying the main fouling mechanisms during membrane filtration with statistical confidence.
18
Li, Juan, Liming Zhao, Yaosong Wang, Chaoqin Chen, Jiachun Zhou, Yongjun Qiu e Hailong Du. "Analysis of membrane fouling by proteins during nanofiltration of chitin alkali wastewater". Journal of Water Reuse and Desalination 4, n. 4 (22 aprile 2014): 253–62. http://dx.doi.org/10.2166/wrd.2014.005.
Testo completoAbstract (sommario):
The membrane fouling mechanism used during the nanofiltration (NF) of chitin alkali effluent was investigated. Tests were carried out in three large-scale chitin-processing plants with three kinds of wastewater. An alkali resistant NF membrane with molecular weight cut-off of 250 Da was employed. The reflection coefficient (σ) and diffusion coefficient (Ps) of total proteins were deduced, assuming that the proteins were single entities in the feed. Viscosity and osmosis pressure were measured to evaluate their influences on the permeate flux. Furthermore, the fraction of the protein fouling was extracted and qualitatively analyzed by mass spectrometry. Results showed that the NF permeate flux of alkali wastewater with the highest protein concentration (4.00%) was the lowest, and that σ and penetration Ps decreased with protein content growth. Over 60% of the peptides in the permeate were hydrophobic, whereas 70% of the peptides in the adsorption cake were hydrophilic. Irreversible resistance was the predominant resistance during NF processing, and the fouling behaviour of hydrophilic fractions was dominant.
19
Sioutopoulos, Dimitrios, Anastasios Karabelas e Vasileios Mappas. "Membrane Fouling Due to Protein—Polysaccharide Mixtures in Dead-End Ultrafiltration; the Effect of Permeation Flux on Fouling Resistance". Membranes 9, n. 2 (1 febbraio 2019): 21. http://dx.doi.org/10.3390/membranes9020021.
Testo completoAbstract (sommario):
Significant gaps exist in our knowledge of ultrafiltration (UF) membrane fouling, due to mixtures of poly-saccharides and proteins, despite a fair amount of related research. To get new insights into fouling layer characteristics, experiments were performed under constant-flux, within the range of practical interest (15–90 L/m2h), with typical polysaccharides (sodium alginate, SA), proteins (bovine serum albumin, BSA) as well as their mixtures in various proportions (1:3, 1:1, 3:1), and total organic matter concentration of 30 mg/L. The feed-water salinity and calcium ion concentration were 2000 mg/L NaCl and 2 mM, respectively. The temporal evolution of such fouling layers on flat-sheet membranes was monitored by recording the trans-membrane pressure variation. The results show that the specific fouling resistance α is strongly affected by flux, and the fouling propensity of polysaccharide-protein mixtures is significantly enhanced compared to single foulants, i.e., when BSA and SA are alone. The fouling layers are compressible and their resistance α tends to increase with the mass ratio of alginate in the mixture, particularly at high fluxes. To quantify these effects, correlations are presented of the initial fouling resistance αi with permeate flux J and of the evolution of α. R&D priorities are suggested on this topic of mixed foulants.
20
Alresheedi, Mohammad T. "Understanding Protein and Polysaccharide Fouling with Silicon Dioxide and Aluminum Oxide in Low-Pressure Membranes". Membranes 13, n. 5 (28 aprile 2023): 476. http://dx.doi.org/10.3390/membranes13050476.
Testo completoAbstract (sommario):
Humic, protein, and polysaccharide substances have been recognized as significant types of foulants in membrane systems. Despite the remarkable amount of research that has been performed on the interaction of these foulants, particularly humic and polysaccharide substances, with inorganic colloids in RO systems, little attention has been paid to the fouling and cleaning behavior of proteins with inorganic colloids in UF membranes. This research examined the fouling and cleaning behavior of bovine serum albumin (BSA) and sodium alginate (SA) with silicon dioxide (SiO2) and α-aluminum oxide (Al2O3) in individual and combined solutions during dead-end UF filtration. The results showed that the presence of SiO2 or Al2O3 in water alone did not cause significant fouling or a flux decline in the UF system. However, the combination of BSA and SA with inorganics was observed to have a synergistic effect on membrane fouling, in which the combined foulants caused higher irreversibility than individual foulants. Analysis of blocking laws demonstrated that the fouling mechanism shifted from cake filtration to complete pore blocking when the combined organics and inorganics were present in water, which resulted in higher BSA and SA fouling irreversibility. The results suggest that membrane backwash needs to be carefully designed and adjusted for better control of BSA and SA fouling with SiO2 and Al2O3.
21
Mapiour, Majak, e Abdelrasoul Amira. "Critical Influences of Plasma pH on Human Protein Properties for Modeling Considerations: Size, Charge, Conformation, Hydrophobicity, and Denaturation". Journal of Composites Science 7, n. 1 (10 gennaio 2023): 28. http://dx.doi.org/10.3390/jcs7010028.
Testo completoAbstract (sommario):
The fouling of biomaterials (e.g., membranes) by plasma proteins has always garnered attention because it renders biomedical devices ineffective and can jeopardize the patient’s well-being. Modeling the fouling process sheds light on its mechanisms and helps improve the biocompatibility of biomaterials. Assuming proteins to be hard spheres with uniform surface properties reduces the modeling complexity, but it seriously deviates from the accurate, real perspective. One reason for the inaccuracy is that proteins’ properties tend to change as environmental factors such as pH and ionic strength are varied. This study critically reviews the pH-induced changes in protein properties, namely size, charge, conformity, hydrophobicity, and denaturation. Though these properties may be interrelated, they are addressed individually to allow for a thorough discussion. The study illustrates the necessity of incorporating the protein property changes resulting from pH alteration to better explain and model the fouling process. The discussion is focused on human serum albumin and fibrinogen. Human serum albumin is the most abundant plasma protein, while fibrinogen plays a major role in blood clotting and triggering of the thrombogenic response.
22
Luo, Xitao, Lingling Sun, Qinghui Shou, Xiangfeng Liang e Huizhou Liu. "Electrodialysis Deacidification of Acid Hydrolysate in Hemicellulose Saccharification Process: Membrane Fouling Identification and Mechanisms". Membranes 13, n. 3 (21 febbraio 2023): 256. http://dx.doi.org/10.3390/membranes13030256.
Testo completoAbstract (sommario):
Acid saccharification of hemicelluloses offers promising pathways to sustainably diversify the revenue of the lignocellulose biorefinery industry. Electrodialysis to separate inorganic acids from acid hydrolysate in the hemicellulose saccharification process could realize the recovery of sulfuric acid, and significantly reduced the chemical consumption than the traditional ion exchange resins method. In this work, the deacidification of corncob acid hydrolysate was conducted by a homemade electrodialysis apparatus. The results showed that: (1) more than 99% of acid can be removed through the electrodialysis process; (2) A non-negligible membrane fouling occurred during the electrodialysis process, which aggravated with the repeated batch running The final global system resistance rose from 15.8 Ω (1st batch) to 43.9 Ω (10th batch), and the treatment ending time was delayed from 120 min (1st batch) to 162 min (10th batch); (4) About 90% of protein, 70% of ferulate acid, and 80% of p-coumarate acid precipitated from the corncob acid hydrolysate during the electrodialysis process. The zeta potential of corncob acid hydrolysate changed from a positive value to a negative value, and an isoelectric point around pH 2.3 was reached. HSQC, FTTR, and GPC, along with SEM and EDS analysis, revealed that the fouling layers mostly consisted of hydrolysates of protein and lignin. The result of HSQC indicated that the membrane foulant may exist in the form of lignin–carbohydrate complexes, as the lignin component of the membrane foulant is in the form of p-coumarate and ferulate. From the result of FTIR, a strong chemical bonding, such as a covalent linkage, existed between the lignin and protein in the membrane foulant. Throughout the electrodialysis process, the increased pH decreased the stability of colloidal particles, including lignin and proteins. Destabilized colloidal particles started to self-aggregate and form deposits on the anion exchange membrane’s surface. Over time, these deposits covered the entire membrane surface and the spaces between the membranes. Eventually, they attached to the surface of the cation exchange membrane. In the end, a suggestion to control and minimize membrane fouling in this process was discussed: lower pH as a process endpoint and a post-treatment method.
23
El Batouti, Mervette, Nouf F. Alharby e Mahmoud M. Elewa. "Review of New Approaches for Fouling Mitigation in Membrane Separation Processes in Water Treatment Applications". Separations 9, n. 1 (21 dicembre 2021): 1. http://dx.doi.org/10.3390/separations9010001.
Testo completoAbstract (sommario):
This review investigates antifouling agents used in the process of membrane separation (MS), in reverse osmosis (RO), ultrafiltration (UF), nanofiltration (NF), microfiltration (MF), membrane distillation (MD), and membrane bioreactors (MBR), and clarifies the fouling mechanism. Membrane fouling is an incomplete substance formed on the membrane surface, which will quickly reduce the permeation flux and damage the membrane. Foulant is colloidal matter: organic matter (humic acid, protein, carbohydrate, nano/microplastics), inorganic matter (clay such as potassium montmorillonite, silica salt, metal oxide, etc.), and biological matter (viruses, bacteria and microorganisms adhering to the surface of the membrane in the case of nutrients) The stability and performance of the tested nanometric membranes, as well as the mitigation of pollution assisted by electricity and the cleaning and repair of membranes, are reported. Physical, chemical, physico-chemical, and biological methods for cleaning membranes. Biologically induced biofilm dispersion effectively controls fouling. Dynamic changes in membrane foulants during long-term operation are critical to the development and implementation of fouling control methods. Membrane fouling control strategies show that improving membrane performance is not only the end goal, but new ideas and new technologies for membrane cleaning and repair need to be explored and developed in order to develop future applications.
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Md Zain, Masniroszaime, e Abdul Wahab Mohammad. "Clarification of Glucose from Cellulose Hydrolysate by Ultrafiltration with Polyethersulfone Membrane". International Journal of Biomass and Renewables 5, n. 1 (18 giugno 2016): 14. http://dx.doi.org/10.61762/ijbrvol5iss1art13916.
Testo completoAbstract (sommario):
Ultrafiltration was used to clarify glucose from cellulose hydrolysate using polyethersulfone (PES) membrane. The flux behavior of PES membrane was studied in concentrating glucose from cellulose hydrolysate during dead end ultrafiltration in different pH of solutions and Kumar’s model was applied to analyse the fouling mechanism. The permeation of glucose achieved more than 93% for all the different pH solution. The permeate flux decreased over time as a result of membrane fouling. The minimum fouling was obtained at pH solution above the IEP due to protein-protein and membrane-protein repulsions alleviating aggregation and fouling. Cake formation blocking was identified as the dominant mechanism for flux decline.
Keywords: glucose, enzyme hydrolysis, lignocellulosic biomass, ultrafiltration, polyethersulfone
25
Pelegrine, D. H. G., M. T. M. S. Gomes e Carlos Alberto Gasparetto. "Temperature effect on whey protein fouling". Publicaciones e Investigación 2, n. 1 (15 giugno 2008): 15. http://dx.doi.org/10.22490/25394088.1134.
Testo completoAbstract (sommario):
<p align="left">El presente trabajo es un estudio del fenómeno de incrustación de la proteína del suero de leche al interior de un intercambiador de calor por donde fuye agua caliente por entre los dos tubos. La cinética de incrustación depende de los efectos de la transferencia de masa, que es una función de la solubilidad de las proteínas. Para describir la cinética de incrustación de las proteínas se desarrolló un algoritmo de cálculo dependiente de la solubilidad. La solubilidad de la proteína fue determinada en una investigación por separado. Los resultados mostraron que el tiempo necesario para que el tubo de radio interior disminuyera en un 30% de la radio original fue menor para altas temperaturas. Además, la deposición de las proteínas de suero de leche fue más intensa en la entrada que en la salida. Por lo tanto, la tasa de reducción de radio fue más rápido en esa zona. El experimento para comprobar el algoritmo se llevó a cabo en una planta piloto.</p>
26
Suki, A., A. G. Fane e C. J. D. Fell. "Modeling fouling mechanisms in protein ultrafiltration". Journal of Membrane Science 27, n. 2 (giugno 1986): 181–93. http://dx.doi.org/10.1016/s0376-7388(00)82055-4.
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Simonič, Marjana, e Zorka Novak Pintarič. "Study of Acid Whey Fouling after Protein Isolation Using Nanofiltration". Membranes 11, n. 7 (30 giugno 2021): 492. http://dx.doi.org/10.3390/membranes11070492.
Testo completoAbstract (sommario):
In this paper, nanofiltration (NF) of acid whey after isolation of proteins was studied. Two membranes were tested: NF-99 (Alfa Laval) and DL (Osmonic Desal). Based on previous measurements that determined the highest efficiency in separating lactic acid and lactose whey, the pH was adjusted to 3. First, the most appropriate transmembrane pressure (TMP) was determined based on the highest flux measured. The TMP range was 5–25 bar for the DL membrane and 10–30 bar for the NF-99 membrane. The temperature was kept at 4 °C using a thermostat. The mechanisms of membrane fouling were investigated. The Hermia models and the modified Tansel model were applied to study the fouling mechanism and to determine which membrane would foul earlier and more severely, respectively. The most suitable TMP was determined at 20 bar. Despite the 1.4 times higher flux of the sample at DL, the fouling rate was higher when NF-99 was used. The results showed that the Tansel model is suitable for predicting the fouling time of protein-isolated whey by nanofiltration.
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Oymaci, Pelin, Pauline E. Offeringa, Zandrie Borneman e Kitty Nijmeijer. "Effect of Osmotic Pressure on Whey Protein Concentration in Forward Osmosis". Membranes 11, n. 8 (29 luglio 2021): 573. http://dx.doi.org/10.3390/membranes11080573.
Testo completoAbstract (sommario):
Forward osmosis (FO) is an emerging process to dewater whey streams energy efficiently. The driving force for the process is the concentration gradient between the feed (FS) and the concentrated draw (DS) solution. Here we investigate not only the effect of the DS concentration on the performance, but also that of the FS is varied to maintain equal driving force at different absolute concentrations. Experiments with clean water as feed reveal a flux increase at higher osmotic pressure. When high product purities and thus low reverse salt fluxes are required, operation at lower DS concentrations is preferred. Whey as FS induces severe initial flux decline due to instantaneous protein fouling of the membrane. This is mostly due to reversible fouling, and to a smaller extent to irreversible fouling. Concentration factors in the range of 1.2–1.3 are obtained. When 0.5 M NaCl is added to whey as FS, clearly lower fluxes are obtained due to more severe concentration polarization. Multiple runs over longer times show though that irreversible fouling is fully suppressed due to salting in/out effects and flux decline is the result of reversible fouling only.
29
Malakian, Anna, e Scott M. Husson. "Evaluating Protein Fouling on Membranes Patterned by Woven Mesh Fabrics". Membranes 11, n. 10 (25 settembre 2021): 730. http://dx.doi.org/10.3390/membranes11100730.
Testo completoAbstract (sommario):
Membrane surface patterning is one approach used to mitigate fouling. This study used a combination of flux decline measurements and visualization experiments to evaluate the effectiveness of a microscale herringbone pattern for reducing protein fouling on polyvinylidene fluoride (PVDF) ultrafiltration membranes. Thermal embossing with woven mesh stamps was used for the first time to pattern membranes. Embossing process parameters were studied to identify conditions replicating the mesh patterns with high fidelity and to determine their effect on membrane permeability. Permeability increased or remained constant when patterning at low pressure (≤4.4 MPa) as a result of increased effective surface area; whereas permeability decreased at higher pressures due to surface pore-sealing of the membrane active layer upon compression. Flux decline measurements with dilute protein solutions showed monotonic decreases over time, with lower rates for patterned membranes than as-received membranes. These data were analyzed by the Hermia model to follow the transient nature of fouling. Confocal laser scanning microscopy (CLSM) provided complementary, quantitative, spatiotemporal information about protein deposition on as-received and patterned membrane surfaces. CLSM provided a greater level of detail for the early (pre-monolayer) stage of fouling than could be deduced from flux decline measurements. Images show that the protein immediately started to accumulate rapidly on the membranes, likely due to favorable hydrophobic interactions between the PVDF and protein, followed by decreasing rates of fouling with time as protein accumulated on the membrane surface. The knowledge generated in this study can be used to design membranes that inhibit fouling or otherwise direct foulants to deposit selectively in regions that minimize loss of flux.
30
Ran, De Qin, Lin Guo Lu, Li Na Cao, Yong Shang e Wei Dian Zhao. "Assessing Membrane-Protein Interactions Using Fourier Transform Infrared Spectroscopy Technique". Advanced Materials Research 955-959 (giugno 2014): 1496–99. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1496.
Testo completoAbstract (sommario):
Protein fouling has been reported to be one of the main obstacles for the membrane processes applied in water treatment, pharmaceutical industry, and biotechnology, etc. The extent and nature of membrane fouling are by the interfacial interactions between membranes and protein, however, have not been fully understood. In recent years, a Fourier transform infrared (FTIR) spectroscopic method has been developed to quantify and analyze membrane fouling in various conditions and good results have been achieved. The scope of the current paper was to review literature on membrane–protein interactions using FTIR in the membrane systems. It will be conducive to further application of the membrane systems in the future.
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Sousa, Mayko Rannany S., Jaime Lora-García, María-Fernanda López-Pérez e Marc Heran. "Identification of Foulants on Polyethersulfone Membranes Used to Remove Colloids and Dissolved Matter from Paper Mill Treated Effluent". Water 12, n. 2 (29 gennaio 2020): 365. http://dx.doi.org/10.3390/w12020365.
Testo completoAbstract (sommario):
In this study, membrane fouling caused by paperboard mill treated effluent (PMTE) was investigated based on a dead-end ultrafiltration (UF) pilot-scale study. The membranes employed were commercial hydrophobic UF membranes made of polyethersulfone (PES) with a molecular weight cut-off of 10 kDa, 50 kDa, and 100 kDa. Membrane fouling mechanism during dead-end filtration, chemical analysis, field emission scanning electron microscopy (FESEM), energy-dispersive spectrophotometry (EDS), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and 3D fluorescence excitation–emission matrix (3DEEM) analysis were applied to understand which fraction of the dissolved and colloidal substances (DCS) caused the membrane fouling. The results indicated that the phenomenon controlling fouling mechanism tended to be cake layer formation (R2 ≥ 0.98) for all membranes tested. The 3DEEM results indicate that the majority of the organic foulants with fluorescence characteristics on the membrane were colloidal proteins (protein-like substances I+II) and macromolecular proteins (soluble microbial products, SMP-like substances). In addition, polysaccharide (cellulosic species), fatty and resin acid substances were identified on the fouled membrane by the ATR–FTIR analysis and play an important role in membrane fouling. In addition, the FESEM and EDS analyses indicate that the presence of inorganic foulants on the membrane surfaces, such as metal ions and especially Ca2+, can accelerate membrane fouling, whereas Mg and Si are linked to reversible fouling.
32
Wang, Shengli, Xin Lu, Lanhe Zhang, Jingbo Guo e Haifeng Zhang. "Characterization of the Initial Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Effects of Permeation Drag". Membranes 9, n. 9 (17 settembre 2019): 121. http://dx.doi.org/10.3390/membranes9090121.
Testo completoAbstract (sommario):
In this study, the properties of the initial fouling layer on the membrane surface of a bioreactor were investigated under different operating modes (with or without permeate flux) to improve the understanding of the effect of permeation drag on the formation of the initial fouling layer. It was found that protein was the major component in the two types of initial fouling layers, and that the permeation drag enhanced the tryptophan protein-like substances. The attraction of the initial foulants to the polyvinylidene fluoride (PVDF) membrane was ascribed to the high zeta potential and electron donor component (γ−) of the membrane. Thermodynamic analyses showed that the permeation drag-induced fouling layer possessed high hydrophobicity and low γ−. Due to permeation drag, a portion of the foulants overcame an energy barrier before they contacted the membrane surface, which itself possessed a higher fouling propensity. A declining trend of the cohesive strength among the foulants was found with the increasing development of both fouling layers.
33
Kelly, Sean T., e Andrew L. Zydney. "Protein fouling during microfiltration: Comparative behavior of different model proteins". Biotechnology and Bioengineering 55, n. 1 (5 luglio 1997): 91–100. http://dx.doi.org/10.1002/(sici)1097-0290(19970705)55:1<91::aid-bit11>3.0.co;2-6.
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Deschênes Gagnon, Rosie, Marie-Ève Langevin, Florence Lutin e Laurent Bazinet. "Identification of Fouling Occurring during Coupled Electrodialysis and Bipolar Membrane Electrodialysis Treatment for Tofu Whey Protein Recovery". Membranes 14, n. 4 (11 aprile 2024): 88. http://dx.doi.org/10.3390/membranes14040088.
Testo completoAbstract (sommario):
Tofu whey, a by-product of tofu production, is rich in nutrients such as proteins, minerals, fats, sugars and polyphenols. In a previous work, protein recovery from tofu whey was studied by using a coupled environmental process of ED + EDBM to valorize this by-product. This process allowed protein recovery by reducing the ionic strength of tofu whey during the ED process and acidifying the proteins to their isoelectric point during EDBM. However, membrane fouling was not investigated. The current study focuses on the fouling of membranes at each step of this ED and EDBM process. Despite a reduction in the membrane conductivities and some changes in the mineral composition of the membranes, no scaling was evident after three runs of the process with the same membranes. However, it appeared that the main fouling was due to the presence of isoflavones, the main polyphenols in tofu whey. Indeed, a higher concentration was observed on the AEMs, giving them a yellow coloration, while small amounts were found in the CEMs, and there were no traces on the BPMs. The glycosylated forms of isoflavones were present in higher concentrations than the aglycone forms, probably due to their high amounts of hydroxyl groups, which can interact with the membrane matrices. In addition, the higher concentration of isoflavones on the AEMs seems to be due to a combination of electrostatic interactions, hydrogen bonding, and π–π stacking, whereas only π–π stacking and hydrogen bonds were possible with the CEMs. To the best of our knowledge, this is the first study to investigate the potential fouling of BPMs by polyphenols, report the fouling of IEMs by isoflavones and propose potential interactions.
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Castilla-Rodriguez, Edwin, e Hongde Zhou. "Organic Compounds Responsible for the Fouling of Ultrafiltration Membrane Treating Algae-Laden Water". Membranes 13, n. 9 (12 settembre 2023): 787. http://dx.doi.org/10.3390/membranes13090787.
Testo completoAbstract (sommario):
Fouling comparisons of the organic fractions in surface and algae-laden waters make it possible to determine the main compounds responsible for the fouling of ultrafiltration (UF) membranes. This study examined the fouling of UF membranes and its relationship to the characteristics of the organic fractions found in drinking-water supply. Four types of water were prepared by combining natural organic matter (NOM) from lake water with algal organic matter (AOM) from four algae species commonly found in freshwater. Liquid chromatography–organic carbon detection (LC–OCD) and a fluorescence excitation–emission matrix (FEEM) were used to analyze the feed water and permeate to assess the interactions between and fouling behavior of the organic fractions. The results showed that the interaction of large-molecular-weight AOMs on the membrane surfaces and their transport through the membrane pores were the main fouling mechanisms. Polysaccharides followed by protein-like substances were the organic compounds responsible for the fouling of the UF membranes. The fouling affinity of these substances was attributed to two processes, the adsorption of their carboxyl, hydroxyl and cationic groups on the membrane surfaces, and the molecular complexation of their organic groups. The humic substances’ retention was marginal and attributed to the synergetic effects of the polysaccharides and proteins.
36
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.
Testo completoAbstract (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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Fukuda, Makoto, Hiroki Yoshimoto, Hitoshi Saomoto e Kiyotaka Sakai. "Validity of Three-Dimensional Tortuous Pore Structure and Fouling of Hemoconcentration Capillary Membrane Using the Tortuous Pore Diffusion Model and Scanning Probe Microscopy". Membranes 10, n. 11 (29 ottobre 2020): 315. http://dx.doi.org/10.3390/membranes10110315.
Testo completoAbstract (sommario):
Hemoconcentration membranes used in cardiopulmonary bypass require a pore structure design with high pure water permeability, which does not allow excessive protein adsorption and useful protein loss. However, studies on hemoconcentration membranes have not been conducted yet. The purpose of this study was to analyze three-dimensional pore structures and protein fouling before and after blood contact with capillary membranes using the tortuous pore diffusion model and a scanning probe microscope system. We examined two commercially available capillary membranes of similar polymer composition that are successfully used in hemoconcentration clinically. Assuming the conditions of actual use in cardiopulmonary bypass, bovine blood was perfused inside the lumens of these membranes. Pure water permeability before and after bovine blood perfusion was measured using dead-end filtration. The scanning probe microscopy system was used for analysis. High-resolution three-dimensional pore structures on the inner surface of the membranes were observed before blood contact. On the other hand, many pore structures after blood contact could not be observed due to protein fouling. The pore diameters calculated by the tortuous pore diffusion model and scanning probe microscopy were mostly similar and could be validated reciprocally. Achievable pure water permeabilities showed no difference, despite protein fouling on the pore inlets (membrane surface). In addition, low values of albumin sieving coefficient are attributable to protein fouling that occurs on the membrane surface. Therefore, it is essential to design the membrane structure that provides the appropriate control of fouling. The characteristics of the hemoconcentration membranes examined in this study are suitable for clinical use.
38
Rode, Richard, Michael Schmid e Saeed Moghaddam. "Protein Fouling Characteristics of Graphene Oxide Membranes". Advanced Materials Interfaces 9, n. 4 (19 dicembre 2021): 2101613. http://dx.doi.org/10.1002/admi.202101613.
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Hedayati, Mohammadhasan, Matt J. Kipper e Diego Krapf. "Anomalous protein kinetics on low-fouling surfaces". Physical Chemistry Chemical Physics 22, n. 9 (2020): 5264–71. http://dx.doi.org/10.1039/d0cp00326c.
Testo completoAbstract (sommario):
Single-molecule tracking reveals the protein bovine serum albumin exhibits anomalous kinetics with a heavy-tailed dwell time distribution on PEG surfaces. This effect is shown to be caused by the ability of the protein to oligomerize in solution.
40
Collier, Nicolas, Dorothée Callens, Pierre Campistron, Bertrand Nongaillard, Maude Jimenez, Ghassan Alogaili, Pascal Debreyne e Guillaume Delaplace. "Ultrasonic Adhesion Measurement of Whey Protein Fouling". Heat Transfer Engineering 36, n. 7-8 (14 novembre 2014): 771–79. http://dx.doi.org/10.1080/01457632.2015.954963.
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Jim, K. J., A. G. Fane, C. J. D. Fell e D. C. Joy. "]Fouling mechanisms of membranes during protein ultrafiltration". Journal of Membrane Science 68, n. 1-2 (aprile 1992): 79–91. http://dx.doi.org/10.1016/0376-7388(92)80151-9.
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Güell, Carme, e Robert H. Davis. "Membrane fouling during microfiltration of protein mixtures". Journal of Membrane Science 119, n. 2 (ottobre 1996): 269–84. http://dx.doi.org/10.1016/0376-7388(96)80001-j.
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Paone, F., F. Bisignano, G. De Luca e S. Curcio. "Multiscale Modelling of Protein Fouling in Ultrafiltration". Procedia Engineering 44 (2012): 338–40. http://dx.doi.org/10.1016/j.proeng.2012.08.408.
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Mazzei, Rosalinda, Anna Maria Szymczak, Enrico Drioli, Mohamed Al-Fageeh, Mohammed A. Aljohi e Lidietta Giorno. "High Purity of α-Lactalbumin from Binary Protein Mixture by Charged UF Membrane Far from the Isoelectric Point to Limit Fouling". Applied Sciences 11, n. 19 (2 ottobre 2021): 9167. http://dx.doi.org/10.3390/app11199167.
Testo completoAbstract (sommario):
Separation and high recovery factor of proteins similar in molecular mass is a challenging task, and heavily studied in the literature. In this work, a systematic study to separate a binary protein mixture by charged ultrafiltration membranes without affecting membrane performance was carried out. α-lactalbumin (ALA, 14.4 kDa) and β-lactoglobulin (BLG, 18.4 kDa) were used as a binary model system. These two proteins are the main proteins of whey, a very well-known byproduct from the dairy industry. Initially, a systematic characterization of individual proteins was carried out to determine parameters (protein size and aggregation, zeta potential) which could influence their passage through a charged membrane. Then, the influence of operating parameters (such as initial protein concentration, pH, and critical pressure) on the UF process was investigated, so as to identify conditions that limit membrane fouling whilst maximizing protein recovery factor and purity. The study permitted to identify process conditions able to fully separate ALA from BLG, with high purity (95%) and recovery factor (80%), in a single UF step. Compared to studies reported in literature, here, the main approach used was to carry out a charged UF process far from proteins isoelectric point (pI) to limit protein aggregation and membrane fouling.
45
Lin, Zhifeng, Yuhong Ma, Changwen Zhao, Ruichao Chen, Xing Zhu, Lihua Zhang, Xu Yan e Wantai Yang. "An extremely simple method for fabricating 3D protein microarrays with an anti-fouling background and high protein capacity". Lab Chip 14, n. 14 (2014): 2505–14. http://dx.doi.org/10.1039/c4lc00223g.
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Christelle, Guigui, e Nga Vu Thi Thu. "Impacts of the specific cake resistance on mbr fouling for wastewater treatment". Transport and Communications Science Journal 72, n. 7 (15 settembre 2021): 841–49. http://dx.doi.org/10.47869/tcsj.72.7.6.
Testo completoAbstract (sommario):
Membrane bioreactor (MBR) has been increasingly used for municipal wastewater treatment and reuse due to its good effluent quality. However, membrane fouling remains the major limitation of MBR. Understanding fouling is still a key issue for a more sustainable operation of MBRs. Thus, this research presents the influence of specific cake resistance (α) on the fouling propensity in the MBR. Correlation between α value with fouling resistance (Rf), fouling rate (dTMP/dt), especially of peak height 100-1000 kDa protein-like SMPs was investigated. The result reported that the α value was strongly correlated with the dTMP/dt in the MBR (R2 value of close to 1). In this study, however, there is an obvious discrepancy between the fouling resistance calculated from the resistance in the series model and the α value in the supernatant filtration. These observations demonstrated that the fouling propensities of the membrane could be monitored by the transmembrane pressure and the fouling characteristics, include fouling resistance and specific cake resistance in the filtration cell.
47
Piluharto, Bambang, Achmad Sjaifullah, Istiqomah Rahmawati e Maryanto Maryanto. "Polysulfone Membrane with UV-Photografting Technique and it Application at Soya Milk Filtration Processing". Jurnal ILMU DASAR 14, n. 1 (8 gennaio 2013): 39. http://dx.doi.org/10.19184/jid.v14i1.480.
Testo completoAbstract (sommario):
In the separation process of solution containing protein, interaction between membrane surface and protein can cause fouling irreversibely. So, efficiency of filtration process will decline. In this research, to improve the effeciency of filtration was done by modification of membrane using UV-photografting technique. Acrylic acid had been introduced topolysulphone membrane via this technique. The hydrophylic membrane was obtained. The membrane performance was evaluated in soymilk fouling test. The first step of research had obtained PSF membrane optimation about PSF 18%. In second step, the research was focused on the modification and characterization of PSF membrane by UV-Fotografting tehchnique. In this technique, monomer concentration and radiation time was used as variable. As the result, PSF membrane had been modificated succesfully by UV- photografting tehchnique with optimum condition in 15 minutes time radiation and concentration of acrylic acid 5%. Performance of modified membranes (flux and permselectivity) were better than unmodified membranes. The fouling test showed that the modified membranes have reduced fouling degree significantly. Keywords : Ultrafiltration membrane, UV-photografting, flux and permselectivity, fouling
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Ma, Wen, Md Saifur Rahaman e Heloise Therien-Aubin. "Controlling biofouling of reverse osmosis membranes through surface modification via grafting patterned polymer brushes". Journal of Water Reuse and Desalination 5, n. 3 (19 marzo 2015): 326–34. http://dx.doi.org/10.2166/wrd.2015.114.
Testo completoAbstract (sommario):
Thin film composite (TFC) polyamide membranes are extensively used as selective barriers in reverse osmosis processes. The major challenge faced with TFC membranes is significant fouling on the surface, which restricts the overall purification performance. To address the fouling problem, we developed novel fouling-resistant surface coatings via polyelectrolyte [poly(allylamine hydrochloride)/poly(styrene sulfonate)] layer-by-layer self-assembly, functionalized with patterned antimicrobial and antifouling/fouling-release polymer brushes. Two types of different polymer brushes, among antimicrobial poly(quaternary ammonium), antifouling poly(sulfobetaine) and fouling-release poly(dimethylsiloxane) (PDMS), were selected and grafted in a checkerboard pattern, with a square feature of 2 µm. The successful patterning and incorporation of different polymer brushes on the membrane was confirmed through X-ray photoelectron spectroscopy analysis. Grafting with sulfobetaine and PDMS significantly increased the hydrophilicity and lowered the surface energy of the membrane, respectively. The fouling-resistant property of the modified membrane was evaluated via static protein (bovine serum albumin) deposition and bacterial (Escherichia coli) cell adhesion tests. Surface modifications proved to diminish protein adhesion and exhibited 70–93% reduction in bacterial cell attachment. This observation suggests that the modified membranes have strong antifouling properties that inhibit the irreversible adhesion of organic and bio-foulants on the membrane surface.
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Susanto, H., e M. Ulbricht. "Highly fouling resistant ultrafiltration membranes for water and wastewater treatments". Water Supply 8, n. 1 (1 aprile 2008): 19–24. http://dx.doi.org/10.2166/ws.2008.002.
Testo completoAbstract (sommario):
Control of fouling is a critical issue to increase the competitiveness of ultrafiltration (UF) membranes for drinking water and wastewater treatments. Highly fouling resistant UF membranes synthesized by photo-graft copolymerization of a water soluble monomer, poly(ethylene glycol) methacrylate (PEGMA), onto a polyethersulfone UF membrane have been evaluated with respect to the adsorptive as well as the ultrafiltration fouling. Protein, humic substance and polysaccharide solutions were used as the model for foulants occurring in the water sources for drinking water as well as in wastewater effluents. The results show that the modified membranes exhibited a much higher fouling resistance for all foulants than the unmodified membranes. Their combined high fouling resistance and high rejection suggests that the obtained modified membranes are very promising as a new generation of thin-layer composite low fouling UF membranes for drinking water and wastewater treatment applications.
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Yang, Tsou, Hsiao, Cheng, Liu, Huang, Peng, Liu, Yung e Hsu. "Electrochemical Polymerization of PEDOT–Graphene Oxide–Heparin Composite Coating for Anti-fouling and Anti-clotting of Cardiovascular Stents". Polymers 11, n. 9 (18 settembre 2019): 1520. http://dx.doi.org/10.3390/polym11091520.
Testo completoAbstract (sommario):
ABSTRACT: In this study, a novel hemocompatible coating on stainless steel substrates was prepared by electrochemically copolymerizing 3,4-ethylenedioxythiophene (EDOT) with graphene oxide (GO), polystyrene sulfonate (PSS), or heparin (HEP) on SUS316L stainless steel, producing an anti-fouling (anti-protein adsorption and anti-platelet adhesion) surface to avoid the restenosis of blood vessels. The negative charges of GO, PSS, and HEP repel negatively charged proteins and platelets to achieve anti-fouling and anti-clotting. The results show that the anti-fouling capability of the poly(3,4-ethylenedioxythiophene) (PEDOT)/PSS coating is similar to that of the PEDOT/HEP coating. The anti-fouling capability of PEDOT/GO is higher than those of PEDOT/HEP and PEDOT/PSS. The reason for this is that GO exhibits negatively charged functional groups (COO−). The highest anti-fouling capability was found with the PEDOT/GO/HEP coating, indicating that electrochemical copolymerization of PEDOT with GO and HEP enhances the anti-fouling capability. Furthermore, the biocompatibility of the PEDOT coatings was tested with 3T3 cells for 1–5 days. The results show that all PEDOT composite coatings exhibited biocompatibility. The blood clotting time (APTT) of PEDOT/GO/HEP was prolonged to 225 s, much longer than the 40 s of pristine SUS316L stainless steel (the control), thus greatly improving the anti-blood-clotting capability of cardiovascular stents.