Honorary Issue for Prof. Dr. Anastasios Karabelas

A special issue of Membranes (ISSN 2077-0375).

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 29931

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Guest Editor
Chemical Process and Energy Resources Institute, CPERI, Centre for Research and Technology Hellas, CERTH, Thermi, 57001 Thessaloniki, Greece
Interests: membrane bioreactors (MBRs); hybrid biological-membrane processes; waste valorization; recovery and separation of bioactive compounds; membrane processes; wastewater treatment
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Guest Editor
Natural Resources and Renewable Energies Laboratory (NRRE), Centre for Research and Technology, Hellas (CERTH), Chemical Process Engineering Research Institute (CPERI), 6th km Charilaou-Thermi Road, P.O. Box 60361, 57001 Thessaloniki, Greece
Interests: pressure-driven membrane processes; electrodialysis; photo- and electro-driven advanced oxidation processes (AOPs); hybrid AOPs with membrane processes; adsorption processes; water and wastewater treatment; water reuse
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Chemical Process and Energy Resources Institute | CPERI, Centre for Research and Technology Hellas | CERTH, P.O. Box 60361, GR 570 01 Thermi - Thessaloniki, Greece
Interests: water desalination; pressure driven membrane processes; forward osmosis; organic and colloidal fouling; industrial wastewater treatment; water reuse; recovery of valuable compounds; hemodialysis

Special Issue Information

Dear Colleagues,


Prof. Dr. Anastasios J. Karabelas

Membranes is pleased to publish a Special Issue in honor of Dr. Anastasios (Tasos) J. Karabelas, Professor of Chemical Engineering (1978–2005) at Aristotle University of Thessaloniki, Greece and founding member of Chemical Process Engineering Research Institute (CPERI), at the Centre for Research and Technology—Hellas (CERTH), Greece. Prof. Karabelas, a graduate of NTU Athens, after his doctoral studies on multiphase flow processes at the University of Illinois, Urbana, under the supervision of Prof. T.J. Hanratty, was employed (1970–1978) as a Senior Research Engineer at the Shell Westhollow Research Center, Houston. In 1978, he joined the newly founded Chemical Engineering Department at Aristotle University of Thessaloniki and significantly contributed to its organization and development, being extensively involved in teaching and mentoring.

In parallel, since 1985, he has headed the Laboratory of Natural Resources and Renewable Energies (NRRE) of CPERI/CERTH, and he has coordinated many R&D projects on his main research interests including multiphase flow processes, colloidal systems, membrane separation processes with applications to process equipment design and water treatment (desalination, purification), and advanced oxidation processes. His research activities have resulted in more than 210 refereed journal papers, many papers that have appeared in conference proceedings, 6 book chapters, and several patent applications. This work has been recognized by the scientific community with several awards. He has also organized several international scientific events and has served in various technical and science policy committees in Greece and abroad, including Editorial/Advisory boards of scientific journals.

Prof. Tasos Karabelas has been studying membrane processes for more than 20 years, contributing to better understanding the complicated mechanisms of membrane fouling and scaling, developing modeling tools for improved design of membrane modules and spiral wound spacers, as well as developing and demonstrating novel hybrid membrane processes (photocatalytic membrane reactor, membrane bioreactor, etc.) for advanced water and wastewater treatment applications. His keen interest in integrated studies of basic phenomena and related membrane processes, from the microscale (surface–particles interactions) to full-scale membrane process design, is reflected in the extensive collection of his relevant publications.

In honor and recognition of Prof. Karabelas’s life-long scientific and educational contributions to the field of membrane separation processes and technologies, this Special Issue of Membranes welcomes the submission of original research manuscripts or reviews in the areas of membrane separation processes, hybrid membrane technologies, and membrane science advancement. The deadline for submission of manuscripts is 15 December 2021. Manuscripts will be published online on an ongoing basis after due processing.

Dr. Sotiris I. Patsios
Dr. Konstantinos V. Plakas
Dr. Dimitris C. Sioutopoulos
Guest Editors

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Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (11 papers)

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Research

24 pages, 11521 KiB  
Article
Improvement of MBBR-MBR Performance by the Addition of Commercial and 3D-Printed Biocarriers
by Dimitra C. Banti, Petros Samaras, Eleni Kostopoulou, Vassiliki Tsioni and Themistoklis Sfetsas
Membranes 2023, 13(8), 690; https://doi.org/10.3390/membranes13080690 - 25 Jul 2023
Cited by 1 | Viewed by 1066
Abstract
Moving bed biofilm reactor combined with membrane bioreactor (MBBR-MBR) constitute a highly effective wastewater treatment technology. The aim of this research work was to study the effect of commercial K1 biocarriers (MBBR-MBR K1 unit) and 3D-printed biocarriers fabricated from 13X and Halloysite (MBBR-MBR [...] Read more.
Moving bed biofilm reactor combined with membrane bioreactor (MBBR-MBR) constitute a highly effective wastewater treatment technology. The aim of this research work was to study the effect of commercial K1 biocarriers (MBBR-MBR K1 unit) and 3D-printed biocarriers fabricated from 13X and Halloysite (MBBR-MBR 13X-H unit), on the efficiency and the fouling rate of an MBBR-MBR unit during wastewater treatment. Various physicochemical parameters and trans-membrane pressure were measured. It was observed that in the MBBR-MBR K1 unit, membrane filtration improved reaching total membrane fouling at 43d, while in the MBBR-MBR 13X-H and in the control MBBR-MBR total fouling took place at about 32d. This is attributed to the large production of soluble microbial products (SMP) in the MBBR-MBR 13X-H, which resulted from a large amount of biofilm created in the 13X-H biocarriers. An optimal biodegradation of the organic load was concluded, and nitrification and denitrification processes were improved at the MBBR-MBR K1 and MBBR-MBR 13X-H units. The dry mass produced on the 13X-H biocarriers ranged at 4980–5711 mg, three orders of magnitude larger than that produced on the K1, which ranged at 2.9–4.6 mg. Finally, it was observed that mostly extracellular polymeric substances were produced in the biofilm of K1 biocarriers while in 13X-H mostly SMP. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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13 pages, 2542 KiB  
Article
A Straightforward Method to Prepare MOF-Based Membranes via Direct Seeding of MOF-Polymer Hybrid Nanoparticles
by Mingyuan Fang, Martin Drobek, Didier Cot, Carmen Montoro and Mona Semsarilar
Membranes 2023, 13(1), 65; https://doi.org/10.3390/membranes13010065 - 04 Jan 2023
Cited by 4 | Viewed by 1581
Abstract
Metal Organic Frameworks (MOFs) present high surface areas, various pore topology as well as good stabilities. The functionalities and porosity can be tuned by using different linkers with various functional groups and a wide range of linker lengths. These properties make them good [...] Read more.
Metal Organic Frameworks (MOFs) present high surface areas, various pore topology as well as good stabilities. The functionalities and porosity can be tuned by using different linkers with various functional groups and a wide range of linker lengths. These properties make them good candidates in membrane separation applications. In this work, we propose a simple UiO-66 MOF-based membrane fabrication method following two steps. First, the α-alumina tubular membrane support was dip-coated with MOF-polymer hybrid nanoparticles (NPs). These NPs were prepared via one-pot synthesis by adding poly (methacrylic acid)-b-poly (methyl methacrylate) (PMAA-b-PMMA) NPs to the classical acetic acid-modulated UiO-66 or UiO-66-NH2 synthesis formulation. Second, secondary membrane growth was applied to give rise to a continuous and homogeneous crystalline MOF membrane layer. The gas permeances (He, N2, CO2 and SF6) tests confirmed high membrane permeability with no macro-defects. The as-prepared membranes that were used for dye separation (Rhodamine B) showed relatively good separation capacity. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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15 pages, 2743 KiB  
Article
The Effect of Heat Sterilization on Key Filtration Performance Parameters of a Commercial Polymeric (PVDF) Hollow-Fiber Ultrafiltration Membrane
by Alexandra Nastouli, Asimina Tsirigka, Michael Harasek, Anastasios J. Karabelas and Sotiris I. Patsios
Membranes 2022, 12(8), 725; https://doi.org/10.3390/membranes12080725 - 22 Jul 2022
Cited by 2 | Viewed by 1706
Abstract
Membrane processes can be integrated with fermentation for the selective separation of the products from the fermentation broth. Sterilization with saturated steam under pressure is the most widely used method; however, data concerning heat sterilization applicability to polymeric ultrafiltration (UF) membranes are scarcely [...] Read more.
Membrane processes can be integrated with fermentation for the selective separation of the products from the fermentation broth. Sterilization with saturated steam under pressure is the most widely used method; however, data concerning heat sterilization applicability to polymeric ultrafiltration (UF) membranes are scarcely available. In this study, the effect of the sterilization process on the filtration performance of a commercial polyvinylidene difluoride (PVDF) hollow fiber UF membrane was evaluated. Membrane modules were constructed and sterilized several times in an autoclave. Pure water flux tests were performed, to assess the effect of heat sterilization on the membrane’s pure water permeance. Dextran rejection tests were performed for the characterization of membrane typical pore size and its fouling propensity. Filtration performance was also assessed by conducting filtration tests with real fermentation broth. After repeated sterilization cycles, pure water permeance remained quite constant, varying between approx. 830 and 990 L·m−2·h−1·bar−1, while the molecular weight cut-off (MWCO) was estimated to be in the range of 31.5–98.0 kDa. Regarding fouling behavior, the trans-membrane pressure increase rate was stable and quite low (between 0.5 and 7.0 mbar/min). The results suggest that commercial PVDF UF membranes are a viable alternative to high-cost ceramic UF membranes for fermentation processes that require heat sterilization. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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13 pages, 1235 KiB  
Article
Sequential Membrane Filtration to Recover Polyphenols and Organic Acids from Red Wine Lees: The Antioxidant Properties of the Spray-Dried Concentrate
by Polychronis Filippou, Soultana T. Mitrouli and Patroklos Vareltzis
Membranes 2022, 12(4), 353; https://doi.org/10.3390/membranes12040353 - 23 Mar 2022
Cited by 8 | Viewed by 2151
Abstract
The vinification process produces a considerable amount of waste. Wine lees are the second most generated byproduct, representing around 14% of total vinification wastes. They are a valuable source of natural antioxidants, mainly polyphenols, as well as organic acids, such as tartaric acid. [...] Read more.
The vinification process produces a considerable amount of waste. Wine lees are the second most generated byproduct, representing around 14% of total vinification wastes. They are a valuable source of natural antioxidants, mainly polyphenols, as well as organic acids, such as tartaric acid. This paper deals with the application of an integrated, environment friendly membrane separation process to recover polyphenols and organic acids. A two-step membrane process is described, consisting of an ultra- and a nano-filtration process. The physicochemical and antioxidant properties of all the process streams were determined. High Pressure Liquid Chromatography (HPLC) was employed for identifying certain individual organic acids and polyphenols, while the antioxidant potential was determined by the 2,2′-diphenyl-1-picrylhydrazyl radical) (DPPH) radical scavenging ability and ferric reducing ability. A liquid concentrate stream containing 1351 ppm of polyphenols was produced and then spray dried. The resulting powder retained most of the polyphenols and antioxidant properties and was successfully applied to a real food system to retard lipid oxidation, followed by Thiobarbituric Acid Reactive Substances (TBARS) and the determination of oxymyoglobin content. The results show that membrane separation technology is an attractive alternative process for recovering value-added ingredients from wine lees. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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18 pages, 7585 KiB  
Article
Permeation Increases Biofilm Development in Nanofiltration Membranes Operated with Varying Feed Water Phosphorous Concentrations
by Luisa Javier, Laura Pulido-Beltran, Johannes S. Vrouwenvelder and Nadia M. Farhat
Membranes 2022, 12(3), 335; https://doi.org/10.3390/membranes12030335 - 18 Mar 2022
Cited by 4 | Viewed by 2055
Abstract
Nutrient limitation has been proposed as a biofouling control strategy for membrane systems. However, the impact of permeation on biofilm development under phosphorus-limited and enriched conditions is poorly understood. This study analyzed biofilm development in membrane fouling simulators (MFSs) with and without permeation [...] Read more.
Nutrient limitation has been proposed as a biofouling control strategy for membrane systems. However, the impact of permeation on biofilm development under phosphorus-limited and enriched conditions is poorly understood. This study analyzed biofilm development in membrane fouling simulators (MFSs) with and without permeation supplied with water varying dosed phosphorus concentrations (0 and 25 μg P·L−1). The MFSs operated under permeation conditions were run at a constant flux of 15.6 L·m2·h−1 for 4.7 days. Feed channel pressure drop, transmembrane pressure, and flux were used as performance indicators. Optical coherence tomography (OCT) images and biomass quantification were used to analyze the developed biofilms. The total phosphorus concentration that accumulated on the membrane and spacer was quantified by using microwave digestion and inductively coupled plasma atomic emission spectroscopy (ICP-OES). Results show that permeation impacts biofilm development depending on nutrient condition with a stronger impact at low P concentration (pressure drop increase: 282%; flux decline: 11%) compared to a higher P condition (pressure drop increase: 206%; flux decline: 2%). The biofilm that developed at 0 μg P·L−1 under permeation conditions resulted in a higher performance decline due to biofilm localization and spread in the MFS. A thicker biofilm developed on the membrane for biofilms grown at 0 μg P·L−1 under permeation conditions, causing a stronger effect on flux decline (11%) compared to non-permeation conditions (5%). The difference in the biofilm thickness on the membrane was attributed to a higher phosphorus concentration in the membrane biofilm under permeation conditions. Permeation has an impact on biofilm development and, therefore, should not be excluded in biofouling studies. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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26 pages, 4954 KiB  
Article
Can Large-Scale Offshore Membrane Desalination Cost-Effectively and Ecologically Address Water Scarcity in the Middle East?
by Daniel Janowitz, Sophie Groche, Süleyman Yüce, Thomas Melin and Thomas Wintgens
Membranes 2022, 12(3), 323; https://doi.org/10.3390/membranes12030323 - 14 Mar 2022
Cited by 7 | Viewed by 5925
Abstract
The Middle East will face tremendous water scarcity by 2050, which can only be mitigated by large-scale reverse osmosis seawater desalination. However, the coastal land in the region is rare and costly, so outsourcing the desalination facility to artificial islands could become a [...] Read more.
The Middle East will face tremendous water scarcity by 2050, which can only be mitigated by large-scale reverse osmosis seawater desalination. However, the coastal land in the region is rare and costly, so outsourcing the desalination facility to artificial islands could become a realistic scenario. This study investigated the ecological and economic challenges and possible advantages of that water supply option by analysing conceptual alternatives for offshore membrane-based desalination plants of up to 600 MCM/y capacity. Key environmental impacts and mitigation strategies were identified, and a detailed economic analysis was conducted to compare the new approach to state-of-the-art. The economic analysis included calculating the cost of water production (WPC) and discussing the differences between offshore alternatives and a conventional onshore desalination plant. In addition, the study investigated the impact of a changing energy mix and potential carbon tax levels on the WPC until 2050. The results indicate that offshore desalination plants have ecological advantages compared to onshore desalination plants. Furthermore, the construction cost for the artificial islands has a much lower effect on the WPC than energy cost. In contrast, the impact of potential carbon tax levels on the WPC is significant. The specific construction cost ranges between 287 $/m2 and 1507 $/m2 depending on the artificial island type and distance to the shoreline, resulting in a WPC between 0.51 $/m3 and 0.59 $/m3. This work is the first to discuss the environmental and economic effects of locating large-scale seawater desalination plants on artificial islands. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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15 pages, 2481 KiB  
Article
Tailor-Made Modification of Commercial Ceramic Membranes for Environmental and Energy-Oriented Gas Separation Applications
by Triantafyllia K. Grekou, Dimitris E. Koutsonikolas, George Karagiannakis and Eustathios S. Kikkinides
Membranes 2022, 12(3), 307; https://doi.org/10.3390/membranes12030307 - 09 Mar 2022
Cited by 2 | Viewed by 2262
Abstract
Ceramic membranes have been considered as potential candidates for several gas separation processes of industrial interest, due to their increased thermal and chemical stability compared to polymeric ones. In the present study, commercial Hybrid Silica (HybSi®) membranes have been evaluated and [...] Read more.
Ceramic membranes have been considered as potential candidates for several gas separation processes of industrial interest, due to their increased thermal and chemical stability compared to polymeric ones. In the present study, commercial Hybrid Silica (HybSi®) membranes have been evaluated and modified accordingly, to enhance their gas separation performance for targeted applications, including CO2 removal from flue gas and H2 recovery from hydrogen-containing natural gas streams. The developed membranes have been characterized before and after modification by relative permeability, single gas permeation, and equimolar separation tests of the respective gas mixtures. The modification procedures, involving in situ chemical vapor deposition and superficial functionalization, aim for precise control of the membranes’ pore size and surface chemistry. High performance membranes have been successfully developed, presenting an increase in H2/CH4 permselectivity from 12.8 to 45.6 at 250 °C. Ultimately, the modified HybSi® membrane exhibits a promising separation performance at 250 °C, and 5 bar feed pressure, obtaining above 92% H2 purity in the product stream combined with a notable H2 recovery of 65%, which can be further improved if a vacuum is applied on the permeate side, leading to 94.3% H2 purity and 69% H2 recovery. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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14 pages, 3345 KiB  
Article
Evaluation of Nanofiltration Membranes for Pure Lactic Acid Permeability
by Mayuki Cabrera-González, Amal Ahmed, Khaled Maamo, Mohammad Salem, Christian Jordan and Michael Harasek
Membranes 2022, 12(3), 302; https://doi.org/10.3390/membranes12030302 - 08 Mar 2022
Cited by 10 | Viewed by 2730
Abstract
Lactic acid (LA) is an organic acid produced by fermentation or chemical synthesis. It plays a crucial role in the pharmaceutical, food and plastic industries. In the fermentation of, for example, grass silage, LA and different compounds are produced. To purify lactic acid, [...] Read more.
Lactic acid (LA) is an organic acid produced by fermentation or chemical synthesis. It plays a crucial role in the pharmaceutical, food and plastic industries. In the fermentation of, for example, grass silage, LA and different compounds are produced. To purify lactic acid, researchers have tried to investigate membrane technology to achieve a high yield of lactic acid permeance. This study tested four commercially available nanofiltration membranes (NF270, MPF-36, Toray NF, and Alfa Laval NF). Nanofiltration experiments were performed to investigate the rejection levels of lactic acid from a binary solution by using distinct molecular weight cut off membranes. All of the experiments were conducted with a lab-scale cross-flow membrane unit. Different operating conditions (pH, temperature) were studied for each membrane; the optimal process condition was found at 25 °C and pH 2.8. With higher temperatures and pH, an increase in LA rejection was observed. The MPF-36 membrane shows the lowest lactic acid rejection yield of 7%, while NF270 has the highest rejection yield of 71% at 25 °C and pH 2.8. These results will be helpful in the future to understand both the interaction of lactic acid permeance through nanofiltration membranes and process scale-up. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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16 pages, 2015 KiB  
Article
A Novel Application of Recycled Ultrafiltration Membranes in an Aerobic Membrane Bioreactor (aMBR): A Proof-of-Concept Study
by Laura Rodríguez-Sáez, Sotiris I. Patsios, Jorge Senán-Salinas, Junkal Landaburu-Aguirre, Serena Molina and Eloy García-Calvo
Membranes 2022, 12(2), 218; https://doi.org/10.3390/membranes12020218 - 14 Feb 2022
Cited by 4 | Viewed by 2170
Abstract
The use of recycled ultrafiltration (r-UF) membranes, originating from end-of-life reverse osmosis membranes, as submerged flat-sheet membranes in an aerobic membrane bioreactor (aMBR) system is described herein for the first time. A feasibility study of this new approach was performed in a laboratory-scale [...] Read more.
The use of recycled ultrafiltration (r-UF) membranes, originating from end-of-life reverse osmosis membranes, as submerged flat-sheet membranes in an aerobic membrane bioreactor (aMBR) system is described herein for the first time. A feasibility study of this new approach was performed in a laboratory-scale aMBR system. The r-UF membrane performance was evaluated in terms of permeability, fouling behavior, and permeate quality using a widely used commercial flat sheet microfiltration membrane (c-MF) as a reference. Tests were conducted under steady-flux operation (at 12 and 14 L·m−2·h−1) and a variable trans-membrane pressure. Synthetic wastewater simulating urban wastewater characteristics with approx. 0.4–0.5 g/L COD concentration was used as the feed. The obtained results showed that the rejection performance of the r-UF membrane was similar to the performance of the commercial flat sheet microfiltration membrane (c-MF) under comparable operating conditions. Moreover, concerning fouling behavior, the r-UF membrane exhibited higher fouling resistance compared with the c-MF membrane, although the permeability decline rate was lower. Both membranes had comparable fouling mechanisms behavior, with cake layer fouling resistance accounting for approx. 60% of the total fouling resistance. Finally, a preliminary economic assessment pointed out the potential competitiveness of using r-UF membranes for aMBRs (5.9–10.9 EUR·m−2) and the scaling-up challenges toward industrial applications. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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26 pages, 1589 KiB  
Article
A Neural Network Based Superstructure Optimization Approach to Reverse Osmosis Desalination Plants
by Marcello Di Martino, Styliani Avraamidou and Efstratios N. Pistikopoulos
Membranes 2022, 12(2), 199; https://doi.org/10.3390/membranes12020199 - 09 Feb 2022
Cited by 14 | Viewed by 2419
Abstract
An ever-growing population together with globally depleting water resources pose immense stresses for water supply systems. Desalination technologies can reduce these stresses by generating fresh water from saline water sources. Reverse osmosis (RO), as the industry leading desalination technology, typically involves a complex [...] Read more.
An ever-growing population together with globally depleting water resources pose immense stresses for water supply systems. Desalination technologies can reduce these stresses by generating fresh water from saline water sources. Reverse osmosis (RO), as the industry leading desalination technology, typically involves a complex network of membrane modules that separate unwanted particles from water. The optimal design and operation of these complex RO systems can be computationally expensive. In this work, we present a modeling and optimization strategy for addressing the optimal operation of an industrial-scale RO plant. We employ a feed-forward artificial neural network (ANN) surrogate modeling representation with rectified linear units as activation functions to capture the membrane behavior accurately. Several ANN set-ups and surrogate models are presented and evaluated, based on collected data from the H2Oaks RO desalination plant in South-Central Texas. The developed ANN is then transformed into a mixed-integer linear programming formulation for the purpose of minimizing energy consumption while maximizing water utilization. Trade-offs between the two competing objectives are visualized in a Pareto front, where indirect savings can be uncovered by comparing energy consumption for an array of water recoveries and feed flows. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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18 pages, 4683 KiB  
Article
Performance Comparison of Alternative Hollow-Fiber Modules for Hemodialysis by Means of a CFD-Based Model
by Nunzio Cancilla, Luigi Gurreri, Gaspare Marotta, Michele Ciofalo, Andrea Cipollina, Alessandro Tamburini and Giorgio Micale
Membranes 2022, 12(2), 118; https://doi.org/10.3390/membranes12020118 - 20 Jan 2022
Cited by 4 | Viewed by 4139
Abstract
Commercial hemodialyzers are hollow-fiber cylindrical modules with dimensions and inlet–outlet configurations dictated mostly by practice. However, alternative configurations are possible, and one may ask how they would behave in terms of performance. In principle, it would be possible to depart from the standard [...] Read more.
Commercial hemodialyzers are hollow-fiber cylindrical modules with dimensions and inlet–outlet configurations dictated mostly by practice. However, alternative configurations are possible, and one may ask how they would behave in terms of performance. In principle, it would be possible to depart from the standard counter-flow design, while still keeping high clearance values, thanks to the increase in the shell-side Sherwood number (Sh) due to the cross-flow. To elucidate these aspects, a previously developed computational model was used in which blood and dialysate are treated as flowing through two interpenetrating porous media. Measured Darcy permeabilities and mass transfer coefficients derived from theoretical arguments and CFD simulations conducted at unit-cell scale were used. Blood and dialysate were alternately simulated via an iterative strategy, while appropriate source terms accounted for water and solute exchanges. Several module configurations sharing the same membrane area, but differing in overall geometry and inlet–outlet arrangement, were simulated, including a commercial unit. Although the shell-side Sherwood number increased in almost all the alternative configurations (from 14 to 25 in the best case), none of them outperformed in terms of clearance the commercial one, approaching the latter (257 vs. 255 mL/min) only in the best case. These findings confirmed the effectiveness of the established commercial module design for the currently available membrane properties. Full article
(This article belongs to the Special Issue Honorary Issue for Prof. Dr. Anastasios Karabelas)
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