Editorial

3 pages, 171 KiB

Open AccessEditorial

Modeling, Simulation, and Optimization of Membrane Processes

by Mingheng Li

Separations 2023, 10(5), 303; https://doi.org/10.3390/separations10050303 - 10 May 2023

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From water desalination and gas purification to metal recovery and beyond, membrane separation has become integral to numerous industrial applications [...] Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

Research

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13 pages, 3831 KiB

Open AccessArticle

Optimizing Membrane Distillation Performance through Flow Channel Modification with Baffles: Experimental and Computational Study

by Yaoling Zhang, Xingsen Mu, Jiaqi Sun and Fei Guo

Separations 2023, 10(9), 485; https://doi.org/10.3390/separations10090485 - 05 Sep 2023

Viewed by 841

Abstract

It has been identified that temperature polarization and concentration polarization are typical near-surface phenomena limiting the performance of membrane distillation. The module design should allow for effective flow, reducing the polarization effects near the membrane surfaces and avoiding high hydrostatic pressure drops across [...] Read more.

It has been identified that temperature polarization and concentration polarization are typical near-surface phenomena limiting the performance of membrane distillation. The module design should allow for effective flow, reducing the polarization effects near the membrane surfaces and avoiding high hydrostatic pressure drops across and along the membrane surfaces. A potential route to enhancing the membrane distillation performance is geometry modification on the flow channel by employing baffles as vortex generators, reducing the polarization effects. In this work, various baffles with different structures were fabricated by 3D printing and attached to the feed flow channel shell in an air gap membrane distillation module. The hydrodynamic characteristics of the modified flow channels were systematically investigated via computational fluid dynamics simulations with various conditions. The membrane distillation tests show that adding the baffles to the feed channel can effectively increase the transmembrane flux. The transmembrane flux with rectangular baffles and shield-shaped baffles increases by 21.8% and 28.1% at the feed temperature of 70 °C. Moreover, the shield-shaped baffles in the flow channel not only enhance the transmembrane flux but also maintain a low-pressure drop, making it even more significant. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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15 pages, 5454 KiB

Open AccessArticle

Multiscale Analysis of Permeable and Impermeable Wall Models for Seawater Reverse Osmosis Desalination

by Qingqing Yang, Yi Heng, Ying Jiang and Jiu Luo

Separations 2023, 10(2), 134; https://doi.org/10.3390/separations10020134 - 15 Feb 2023

Cited by 2 | Viewed by 1356

Abstract

In recent years, high permeability membranes (HPMs) have attracted wide attention in seawater reverse osmosis (SWRO) desalination. However, the limitation of hydrodynamics and mass transfer characteristics for conventional spiral wound modules defeats the advantage of HPMs. Feed spacer design is one of the [...] Read more.

In recent years, high permeability membranes (HPMs) have attracted wide attention in seawater reverse osmosis (SWRO) desalination. However, the limitation of hydrodynamics and mass transfer characteristics for conventional spiral wound modules defeats the advantage of HPMs. Feed spacer design is one of the effective ways to improve module performance by enhancing permeation flux and mitigating membrane fouling. Herein, we propose a multiscale modeling framework that integrates a three-dimensional multi-physics model with a permeable wall and an impermeable wall, respectively, at a sub-millimeter scale and a system-level model at a meter scale. Using the proposed solution framework, a thorough quantitative analysis at different scales is conducted and it indicates that the average errors of the friction coefficient and the Sherwood number using the impermeable wall model are less than 2% and 9%, respectively, for commercial SWRO membrane (water permeability 1 L m⁻² h⁻¹ bar⁻¹) and HPMs (3 L m⁻² h⁻¹ bar⁻¹, 5 L m⁻² h⁻¹ bar⁻¹ and 10 L m⁻² h⁻¹ bar⁻¹) systems, compared to the predictions using the permeable wall model. Using both the permeable and impermeable wall models, the system-level simulations, e.g., specific energy consumption, average permeation flux, and the maximum concentration polarization factor at the system inlet are basically the same (error < 2%), while the impermeable wall model has a significant advantage in computational efficiency. The multiscale framework coupling the impermeable wall model can be used to guide the efficient and accurate optimal spacer design and system design for HPMs using, e.g., a machine learning approach. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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13 pages, 3825 KiB

Open AccessArticle

A Study of Copper (II) Ions Removal by Reverse Osmosis under Various Operating Conditions

by Ramzi H. Harharah, Ghassan M. T. Abdalla, Abubakr Elkhaleefa, Ihab Shigidi and Hamed N. Harharah

Separations 2022, 9(6), 155; https://doi.org/10.3390/separations9060155 - 20 Jun 2022

Cited by 12 | Viewed by 2490

Abstract

The study aims to treat artificial wastewater contaminated with copper (II) ions by reverse osmosis using (SEPA CF042 Membrane Test Skid-TFC BW30XFR). Several concentrations of feedstock were prepared. Different operating pressure, temperature, and flow rate were applied. The effect of these operating conditions [...] Read more.

The study aims to treat artificial wastewater contaminated with copper (II) ions by reverse osmosis using (SEPA CF042 Membrane Test Skid-TFC BW30XFR). Several concentrations of feedstock were prepared. Different operating pressure, temperature, and flow rate were applied. The effect of these operating conditions on both the amount of Cu (II) removal and the permeate flux was monitored. The results of the study revealed that both the permeate flux and Cu (II) removal amount were directly proportional to the operating pressure and feed temperature but inversely proportional to the feed concentration. In contrast, the feed flow rate showed a negligible effect on the permeate flux and Cu (II) removal amount. The temperature correction factor (TCF) of the membrane was calculated and was found to be directly proportional to the feed temperature but inversely proportional to the applied pressure. It was seen that the concentration and flow rate of that feed did not affect the temperature correction factor. Mathematical models have been developed based on these experimental data for both permeate flux and the Cu (II) removal. It was noted that the permeate flux model matched the experimental data, while the Cu (II) removal model did not show a perfect match. In addition to the above, the research highlights for subsequent studies the possibility of a deep link between experimental work and mathematical models. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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21 pages, 1721 KiB

Open AccessFeature PaperArticle

Modeling and Life Cycle Assessment of a Membrane Bioreactor–Membrane Distillation Wastewater Treatment System for Potable Reuse

by Callan J. Glover, James A. Phillips, Eric A. Marchand and Sage R. Hiibel

Separations 2022, 9(6), 151; https://doi.org/10.3390/separations9060151 - 13 Jun 2022

Cited by 5 | Viewed by 4542

Abstract

Wastewater treatment for indirect potable reuse (IPR) is a possible approach to address water scarcity. In this study, a novel membrane bioreactor–membrane distillation (MBR-MD) system was evaluated to determine the environmental impacts of treatment compared to an existing IPR facility (“Baseline”). Physical and [...] Read more.

Wastewater treatment for indirect potable reuse (IPR) is a possible approach to address water scarcity. In this study, a novel membrane bioreactor–membrane distillation (MBR-MD) system was evaluated to determine the environmental impacts of treatment compared to an existing IPR facility (“Baseline”). Physical and empirical models were used to obtain operational data for both systems and inform a life cycle inventory. Life cycle assessment (LCA) was used to compare the environmental impacts of each system. Results showed an average 53.7% reduction in environmental impacts for the MBR-MD system when waste heat is used to operate MD; however, without waste heat, the environmental impacts of MBR-MD are significantly higher, with average impacts ranging from 218% to 1400% greater than the Baseline, depending on the proportion of waste heat used. The results of this study demonstrate the effectiveness of the novel MBR-MD system for IPR and the reduced environmental impacts when waste heat is available to power MD. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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17 pages, 33819 KiB

Open AccessArticle

High-Throughput Optimal Design of Spacers Using Triply Periodic Minimal Surfaces in BWRO

by Qiang Chen, Jiu Luo and Yi Heng

Separations 2022, 9(3), 62; https://doi.org/10.3390/separations9030062 - 27 Feb 2022

Cited by 5 | Viewed by 2358

Abstract

The development of advanced feed spacers under different working conditions can enhance the performance of the reverse osmosis (RO) desalination process. The 3D-printed experimental results on triply periodic minimal surfaces (TPMS)-based spacers in previous literature indicate that the spacers have higher permeation flux [...] Read more.

The development of advanced feed spacers under different working conditions can enhance the performance of the reverse osmosis (RO) desalination process. The 3D-printed experimental results on triply periodic minimal surfaces (TPMS)-based spacers in previous literature indicate that the spacers have higher permeation flux of water compared to those of the common commercial spacers. In this paper, a hybrid modeling approach is developed and applied to predict and evaluate the performance of TPMS-based spacers. The effect of feed channels’ height and porosity on the performance of spacers in brackish water RO (BWRO) process is studied by using a high-throughput approach. The predicted pressure drop by new simulations using the TPMS-based spacers (≈0.09–0.27 bar) from inlet to outlet in a typical two-stage BWRO system is reduced by more than 89% than that of using the commercial spacer (≈2.57 bar). Using the designed advanced spacers, the average permeation flux of water increases more than 8.6% compared to that of the commercial one. With the increase in feed channel height and porosity, the performance of spacers is gradually improved. TPMS-based spacers have significant industrial application prospects. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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25 pages, 7487 KiB

Open AccessArticle

On Process Intensification through Membrane Storage Reactors

by John Lowd III, Theodore Tsotsis and Vasilios I. Manousiouthakis

Separations 2021, 8(11), 195; https://doi.org/10.3390/separations8110195 - 20 Oct 2021

Cited by 1 | Viewed by 1502

Abstract

In this work, a dynamic, one-dimensional, first principle-based model of a novel membrane storage reactor (MSR) process is developed and simulated. The resulting governing equations are rendered dimensionless and are shown to feature two dimensionless groups that can be used to affect process [...] Read more.

In this work, a dynamic, one-dimensional, first principle-based model of a novel membrane storage reactor (MSR) process is developed and simulated. The resulting governing equations are rendered dimensionless and are shown to feature two dimensionless groups that can be used to affect process performance. The novel process is shown to intensify production of a desired species through the creation of two physically distinct domains separated by a semipermeable boundary, and dynamic operation. A number of metrics are then introduced and applied to a case study on Steam Methane Reforming, for which a parametric study is carried out which establishes the superior performance of the MSR when compared to a reactor operating at steady state (SSR). Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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11 pages, 1629 KiB

Open AccessArticle

Accurate Determination of Electrical Potential on Ion Exchange Membranes in Reverse Electrodialysis

by Yuting Sun and Lianfa Song

Separations 2021, 8(10), 170; https://doi.org/10.3390/separations8100170 - 04 Oct 2021

Cited by 4 | Viewed by 1782

Abstract

Reverse electrodialysis is a promising membrane technology to generate energy from controlled mixing of water streams of different salinities. Electrical potentials generate on the ion exchange membranes (IEMs) when selective transport of cations and anions across the membranes driven by concentration difference. The [...] Read more.

Reverse electrodialysis is a promising membrane technology to generate energy from controlled mixing of water streams of different salinities. Electrical potentials generate on the ion exchange membranes (IEMs) when selective transport of cations and anions across the membranes driven by concentration difference. The accurate determination of the potentials developed on the IEMs is critical to fairly assess the feasibility of the technology. The Nernst–Planck–Poisson (NPP) equations for IEMs (the membranes with fixed charge) were solved numerically with the boundary updating scheme. The validity of this numerical method was verified by the identical values of Donnan potential obtained with the well-established analytical methods. The suitability and applicability of the classic Teorell–Meyer–Siever (TMS) model were assessed by comparison to the simulation results from the numerical method. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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8 pages, 1041 KiB

Open AccessArticle

Applying a Hydrophilic Modified Hollow Fiber Membrane to Reduce Fouling in Artificial Lungs

by Nawaf Alshammari, Meshari Alazmi and Vajid Nettoor Veettil

Separations 2021, 8(8), 113; https://doi.org/10.3390/separations8080113 - 30 Jul 2021

Cited by 1 | Viewed by 1904

Abstract

Membranes for use in high gas exchange lung applications are riddled with fouling. The goal of this research is to create a membrane that can function in an artificial lung until the actual lung becomes available for the patient. The design of the [...] Read more.

Membranes for use in high gas exchange lung applications are riddled with fouling. The goal of this research is to create a membrane that can function in an artificial lung until the actual lung becomes available for the patient. The design of the artificial lung is based on new hollow fiber membranes (HFMs), due to which the current devices have short and limited periods of low fouling. By successfully modifying membranes with attached peptoids, low fouling can be achieved for longer periods of time. Hydrophilic modification of porous polysulfone (PSF) membranes can be achieved gradually by polydopamine (PSU-PDA) and peptoid (PSU-PDA-NMEG5). Polysulfone (PSU-BSA-35Mg), polysulfone polydopamine (PSUPDA-BSA-35Mg) and polysulfone polydopamine peptoid (PSU-PDA-NMEG5-BSA35Mg) were tested by potting into the new design of gas exchange modules. Both surfaces of the modified membranes were found to be highly resistant to protein fouling permanently. The use of different peptoids can facilitate optimization of the low fouling on the membrane surface, thereby allowing membranes to be run for significantly longer time periods than has been currently achieved. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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10 pages, 1484 KiB

Open AccessFeature PaperArticle

Modeling and Optimization of Membrane Process for Salinity Gradient Energy Production

by Lianfa Song

Separations 2021, 8(5), 64; https://doi.org/10.3390/separations8050064 - 12 May 2021

Cited by 3 | Viewed by 2292

Abstract

When hydraulic pressure was added on the feed side of the membrane in the otherwise conventional pressure retarded osmosis (PRO) process, the production rate of the salinity gradient energy could be significantly increased by manipulating the hydraulic pressures on both sides of the [...] Read more.

When hydraulic pressure was added on the feed side of the membrane in the otherwise conventional pressure retarded osmosis (PRO) process, the production rate of the salinity gradient energy could be significantly increased by manipulating the hydraulic pressures on both sides of the membrane. With hydraulic pressure added on the feed side of the membrane, much higher water flux could be obtained than that under the osmotic pressure of the same value. The osmotic pressure of the draw solution, instead of drawing water through the membrane, was mainly reserved to increase the hydraulic pressure of the permeate. In this way, orders of magnitude higher power density than that in the conventional PRO can be obtained with the same salinity gradient. At the optimal conditions, it was demonstrated that the energy production rates that were much higher than the economical breakeven point could be obtained from the pair of seawater and freshwater with the currently available semipermeable membranes. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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