Hollow Fiber Membrane Module Research Articles

Designing 3D Membrane Modules for Gas Separation Based on Hollow Fibers from Poly(4-methyl-1-pentene).

Designing hollow fiber (HF) membrane modules occupies one of the key positions in the development of efficient membrane processes for various purposes. In developing HF membrane modules, it is very important to have a uniform HF distribution and flow mixing in the shell side to significantly improve mass transfer and efficiency. This work suggests the application of different textile 3D HF structures (braided hoses and woven tape fabrics). The 3D structures consist of melt-spun, dense HFs based on poly(4-methyl-1-pentene) (PMP). Since the textile processing of HFs can damage the wall of the fiber or close the fiber bore, the membrane properties of the obtained structures are tested with a CO2/CH4 mixture in the temperature range of 0 to 40 °C. It is shown that HFs within the textile structure keep the same transport and separation characteristics compared to initial HFs. The mechanical properties of the PMP-based HFs allow their use in typical textile processes for the production of various membrane structures, even at a larger scale. PMP-based membranes can find application in separation processes, where other polymeric membranes are not stable. For example, they can be used for the separation of hydrocarbons or gas mixtures with volatile organic compounds.

Continuous Synthesis of Polymer-Coated Drug Nanoparticles by Heterogeneous Nucleation in a Hollow-Fiber Membrane Module

Continuous Synthesis of Polymer-Coated Drug Nanoparticles by Heterogeneous Nucleation in a Hollow-Fiber Membrane Module

Membrane fouling and removal performance of submerged aerobic membrane bioreactors: a comparative study of optimizing operational conditions and membrane modification

AbstractBACKGROUNDThe effects of sludge retention time, organic loading rate, specific aeration demand per membrane area (SADm) and exploiting poly(vinyl chloride)/polycarbonate/modified silver nanoparticles (PVC/PC/MAg) nanocomposite membrane in membrane fouling and removal performance of submerged membrane bioreactors (SMBRs) were compared. A reference membrane bioreactor (R‐SMBR) having a pure PVC/PC hollow fiber membrane module and no operational condition improvement was used as a reference for comparison.RESULTSThe results revealed that all of the parameters had a considerable influence on improving membrane fouling, among which optimizing SADm and installing nanocomposite membranes in the SMBRs had comparable performances. Although the nanocomposite membrane had excellent potential to boost the membrane flux up to 62% in comparison with the R‐SMBR, it did not play any noticeable roles in rectifying the removal efficiency of the SMBR. On the other hand, not only did SADm increase the membrane flux up to 55%, but it also increased about 5% of COD and 3% of NH4+‐N removal.CONCLUSIONSSludge characteristics were not affected by membrane modification since the concentration of extracellular polymeric substances, soluble microbial products and mean particle size were 110 ± 1 mg g−1 VSS, 54 ± 1 mg L−1 and 50 μm, respectively, for both the R‐SMBR and the SMBR in which the modified membrane was installed. However, the operational parameters could also modify the treatment performance of the SMBRs by positively impacting on sludge characteristics besides mitigating membrane fouling. © 2021 Society of Chemical Industry (SCI).

Preliminary study on air-to-air latent heat exchanger fabricated using hollow fiber composite membrane for air-conditioning applications

In this study, an air-to-air type hollow fiber composite membrane latent heat exchanger was built and its latent heat exchange characteristics were experimentally investigated under various test conditions. Based on experiments conducted on four prototypes, polyethersulfone with 9 wt% of polyvinyl-pyrrolidone was selected as the membrane material suitable for the latent heat exchanger. Using the selected material, shell-and-tube structured hollow fiber membrane modules were fabricated and tested under various operating conditions. The experimental data showed that the proposed membrane modules exhibited 35.3%–82.7% latent effectiveness and moisture removal rates of 0.027–0.124 g/s under various operating conditions; furthermore, the modules could provide latent cooling with few temperature changes. In addition, the results of the parametric analysis indicated that the inlet primary air humidity ratio was a critical factor affecting the latent cooling performance of the proposed system and the optimal ratio of the secondary to primary air flow was 1.0. The number of mass transfer units (NTUm) in the membrane module design should be higher than 1.7 to attain satisfactory latent cooling performance, that is, higher than 70% latent effectiveness.

Oxygen permeation simulation of La0.8Ca0.2Fe0.95O3−δ‐Ag hollow fiber membrane at different modes and flow configurations

AbstractMixed ionic‐electronic conducting La0.8Ca0.2Fe0.95O3−δ‐Ag (LCF‐Ag) ceramic hollow fiber membranes possess high structural stability and up to 2.24‐fold higher oxygen permeation fluxes relative to LCF hollow fibers. In this work, the oxygen permeation of LCF‐Ag hollow fiber membrane module is simulated under sweep gas and vacuum operation modes, whereas the kinetic parameters were obtained by fitting the experimental data with the simplified Tan–Li model. The good correlation obtained from the data regression confirmed the compatibility of the selected model on the LCF‐Ag hollow fiber membrane. The simulated results revealed that the countercurrent flow configuration is generally favored in sweep gas operation given its potential of complete oxygen separation under optimized conditions. For vacuum operation, the oxygen yield is practically the same for both flow configurations at a moderate vacuum setting. At a very low vacuum pressure setting, however, cocurrent flow is preferred over countercurrent flow for maximizing the oxygen yield.

Pilot-scale vacuum membrane distillation for decontamination of simulated radioactive wastewater: System design and performance evaluation

• Pilot-scale VMD plant with 8.0 m 3 /d production was developed. • Design scheme and schematic of VMD pilot plant were detailed. • High DF of 10 4.85 for Cs and high CF of 110.3 were achieved. • Detailed evaluation of energy efficiency through STEC and GOR was conducted. • Heat loss of pilot-scale membrane module as heat pinch effect was analyzed. A pilot-scale vacuum membrane distillation (VMD) demonstration plant for decontamination of radioactive wastewater with 8.0 m 3 /d water production was developed. The design scheme, main components and functions of VMD pilot plant were detailed. Effects of operational parameters on permeate flux, gain output ratio (GOR) and decontamination factor (DF) of simulated radioactive wastewater were analyzed. As feed temperature increased from 70℃ to 90℃, permeate flux grew exponentially from 1.59 kg/(m 2 ·h) to 6.82 kg/(m 2 ·h). High DF 10 4.85 of Cs + and high concentration factor (CF) 110.3 of simulated radioactive wastewater were reached with stable permeate flux in pilot-plant-scale. DF of Cs + and GOR were relatively stable under various operation conditions. The outlet temperature of membrane modules increased with the growth of flow rate, bringing about 9 °C temperature difference between 2 m 3 /h and 14 m 3 /h at the same inlet temperature of 70 °C. The significant heat loss in radial direction as temperature polarization and in axial direction as the heat pinch effect in hollow fiber membrane modules are the main issues for large-scale MD plant. This study demonstrates a remarkable potential of VMD for decontamination of radioactive wastewater and provides an integrated design of VMD pilot-scale plant.

A review on hollow fiber membrane module towards high separation efficiency: Process modeling in fouling perspective

Hollow fiber microfiltration (MF) and ultrafiltration (UF) membrane processes have been extensively used in water purification and biotechnology. However, complicated filtration hydrodynamics wield a negative influence on fouling mitigation and stability of hollow fiber MF/UF membrane processes. Thus, establishing a mathematical model to understand the membrane processes is essential to guide the optimization of module configurations and to alleviate membrane fouling. Here, we present a comprehensive overview of the hollow fiber MF/UF membrane filtration models developed from different theories. The existing models primarily focus on membrane fouling but rarely on the interactions between the membrane fouling and local filtration hydrodynamics. Therefore, more simplified conceptual models and integrated reduced models need to be built to represent the real filtration behaviors of hollow fiber membranes. Future analyses considering practical requirements including complicated local hydrodynamics and nonuniform membrane properties are suggested to meet the accurate prediction of membrane filtration performance in practical application. This review will inspire the development of high-efficiency hollow fiber membrane modules.

Hollow Fiber Membrane Modules for NOx Removal using a Mixture of NaClO3 and NaOH Solutions in the Shell Side as Absorbents

Hollow Fiber Membrane Modules for NOx Removal using a Mixture of NaClO3 and NaOH Solutions in the Shell Side as Absorbents

Modeling and simulation study of oxygen permeation in La0.8Ca0.2Fe0.95O3-δ-Ag hollow fiber membrane module

Mixed ionic-electronic conducting (MIEC) ceramic membranes present an attractive alternative oxygen separation technology to cryogenic distillation and pressure swing adsorption. The model of Tan and Li has been extensively adopted in the oxygen permeation modeling through MIEC hollow fiber membranes. To evaluate the performance of the La0.8Ca0.2Fe0.95O3-δ-Ag hollow fiber membrane module here, the oxygen permeation is simulated numerically by feeding the air into the shell while passing sweep gas or creating a vacuum in the permeate side under different configuration. The simulation results show that countercurrent flow configuration is preferable in the sweep gas mode given its capability to separate oxygen completely under moderate flow rate of feed air. For vacuum mode, both cocurrent and countercurrent flow configurations result in a similar oxygen permeation performance, which lies between the sweep gas mode with countercurrent and cocurrent flow configurations. When abundant oxygen presence is created in the feed side by elevating its flow rate, the sweep gas mode loses its oxygen separation efficiency and is thus outperformed by the vacuum mode.

Effect of Absorbents on NOx Removal through Polyvinylidene Fluoride (PVDF) Hollow Fiber Membrane Modules

NOx (NO and NO2) are air toxins that endanger life and represent a hazard to the environment, such as photochemical smog, global warming, acid rain, ozone depletion, and the occurrence of respiratory infections. Some technological strategies to diminish NOx emissions to meet regulations depend on two techniques: the dry process and the wet process. This study applies polyvinylidene fluoride (PVDF) hollow fiber membrane modules as a medium to remove NOx from solutions containing several absorbents such as hydrogen peroxide and nitric acid (H2O2-HNO3) solutions, sodium chlorite and sodium hydroxide (NaClO2-NaOH) solutions, and sodium chlorate and sodium hydroxide (NaClO3-NaOH) solutions. The experimental results showed that the oxidant’s strength influences NOx removal efficiency, where the absorbent solutions containing hydrogen peroxide had the highest removal efficiency as hydrogen peroxide is the most potent oxidant, followed by sodium chlorite and sodium chlorate. The three pairs of absorbents also gave a high NOx removal efficiency (above 90%), which means that all the absorbents used in the study are very potential to be used to diminish NOx via the wet process. NOx removal efficiency at the same feed gas flow rate increased as the number of fiber and absorbent concentrations is increased. However, NOx removal efficiency is reduced as the feed gas flow rate is increased at the same membrane module and absorbent concentration.

Osmotically enhanced reverse osmosis using hollow fiber membranes

Osmotically enhanced reverse osmosis (OERO) effectively increases the water recovery in desalination as it can reduce the transmembrane osmotic pressure by a sweep solution. Utilizing a model based on mass-transfer principles, we report the performance of a hollow-fiber RO membrane module in OERO as a function of the operating conditions, the fiber geometry, and the membrane properties. The hollow fiber system allows the feed and sweep solutions to flow on both sides of the membrane. To avoid energy-intensive solute/water separation, fertilizer can be employed as a “green” sweep solution as it can be directly used for fertigation (fertilized irrigation). Simulations indicated that the water recovery is significantly enhanced by increasing the water permeance and decreasing the structure parameter of the hollow fiber membranes. Further, an investigation into the role of feed salinity suggests that longer fibers can provide a higher water recovery in the case of low-salinity water reuse, while larger-diameter fibers achieve a more efficient seawater desalination. A single-stage OERO process facilitates the enhancement of water recovery from 35.5 % and 14 % to 36.5 % and 34 % in the case of low-salinity and high-salinity desalinations, respectively. This study provides theoretical perspectives into the design of hollow fiber modules for OERO processes.

Study on flow and heat and mass transfer characteristics of cross-flow poly propylene hollow fiber membrane module

ABSTRACT Hollow fiber membrane solution dehumidification technology is a new type of dehumidification technology combining solution dehumidification and membrane separation. It is currently widely used in the field of air conditioning dehumidification. In this study, membrane dehumidification technology was applied to low-temperature flue gas dehumidification, and a model of regularly arranged hollow fiber membrane modules was established on the basis of a conjugate heat and mass transfer model. The accuracy of the model was verified by comparing it with literature and experimental data, applying a random arrangement of components. Numerical simulation is carried out by COMSOL software. The flue gas velocity, temperature and water vapor concentration field in the module are coupled together, and the flue gas flow and heat and mass transfer characteristics are affected by the distance between the membrane filament tubes. The dehumidification and cooling efficiency of the randomly arranged hollow fiber membrane module can reach 68.3% and 39.1%,respectively, which Close to 72.1% and 48.7% of regularly arranged components. And the components can be optimized based on the model.

3D-macrocycles impregnated polybenzimidazole hollow fiber membranes with excellent organic solvent resistance for industrial solvent recovery

A new strategy to synthesize integrally skinned polybenzimidazole (PBI) hollow fiber membranes for organic solvent nanofiltration (OSN) has been developed in this study by means of covalent modification with α,α′-dibromo-p-xylene (DBX) and then ionic impregnation with 4-sulfocalix [8]arene (SCA8). This double modification strategy endows the PBI hollow fiber membranes with synergistically enhanced chemical stability, mechanical strength and molecular sieving property. The modified PBI hollow fibers have a molecular weight cut-off (MWCO) of 217 Da and a narrow pore size distribution. In addition, the newly developed PBI hollow fiber membranes display a broad-spectrum of applications in various polar, nonpolar, and aprotic polar organic solvents. 1-inch PBI hollow fiber membrane modules are also fabricated to concentrate 10 wt% oil/acetone mixtures under 10 bar for 30 days, which provide an acetone permeance of around 0.35 L m−2 h−1 bar−1 and an oil rejection >99.5% after stabilization. This work may propose a feasible scheme to design OSN hollow fiber membranes and fabricate industrial-size modules with sharp molecular sieving capability to realize angstrom-scale separations in organic solvents.

Numerical Simulation of the Water Vapor Separation of a Moisture-Selective Hollow-Fiber Membrane for the Application in Wood Drying Processes.

In this study, a simplified two-dimensional axisymmetric finite element analysis (FEA) model was developed, using COMSOL Multiphysics® software, to simulate the water vapor separation in a moisture-selective hollow-fiber membrane for the application of air dehumidification in wood drying processes. The membrane material was dense polydimethylsiloxane (PDMS). A single hollow fiber membrane was modelled. The mass and momentum transfer equations were simultaneously solved to compute the water vapor concentration profile in the single hollow fiber membrane. A water vapor removal experiment was conducted by using a lab-scale PDMS hollow fiber membrane module operated at constant temperature of 35 °C. Three operation parameters of air flow rate, vacuum pressure, and initial relative humidity (RH) were set at different levels. The final RH of dehydrated air was collected and converted to water vapor concentration to validate simulated results. The simulated results were fairly consistent with the experimental data. Both experimental and simulated results revealed that the water vapor removal efficiency of the membrane system was affected by air velocity and vacuum pressure. A high water vapor removal performance was achieved at a slow air velocity and high vacuum pressure. Subsequently, the correlation of Sherwood (Sh)–Reynolds (Re)–Schmidt (Sc) numbers of the PDMS membrane was established using the validated model, which is applicable at a constant temperature of 35 °C and vacuum pressure of 77.9 kPa. This study delivers an insight into the mass transport in the moisture-selective dense PDMS hollow fiber membrane-based air dehumidification process, with the aims of providing a useful reference to the scale-up design, process optimization and module development using hollow fiber membrane materials.

A Study of an Air Scouring Integral Immersed Hollow Fiber Membrane Module for Energy Saving and Membrane Fouling Control

Objectives : MBR (Membrane BioReactor) is well established wastewater treatment that combines biological and physical method with high quality effluent. The purpose of this study is to utilize an air scouring integral immersed hollow fiber membrane module through efficient structural improvement developed to reduce membrane fouling. In addition, the scouring aeration was optimized to determine the energy savings.Methods : In this study, membrane fouling test was evaluated in various of scouring aeration flow with range of 40 to 140 m3 air/m2 projected area･hr and influent and effluent was analyzed by water quality standard.Results and Discussion : In scouring aeration test, effective membrane contamination control was possible with supplying 80 m3 air/m2 projected area･hr, scouring aeration rate gradually increased the differential pressure from below 60 m3 air/m2 projected area･hr, which accelerates the membrane contamination phenomenon. By reducing more than 20% of the existing general scouring aeration rate of 100~140 m3 air/m2 projected area･hr, electricity and maintenance costs can be reduced due to aeration control, and at the same time, it is confirmed that the technology has the same performance. The pilot test results of SJMBR with the developed module showed that the effluent was BOD of 1.4 mg/L, COD of 4.2 mg/L, SS of 0.7 mg/L, T-N of 5.56 mg/L, T-P of 0.56 mg/L, total coliform group of 0 ea/mL, and ecotoxicity of 0 TU, respectively.Conclusions : These results are combined, when using an air scouring integral immersed hollow fiber membrane module, it is expected to reduce the amount of scouring air by more than 20% by optimizing the supply of scouring air. In addition, it can also be determined by technology that satisfy the same permeability and treated water quality as existing technologies.

Biological mechanism of alleviating membrane biofouling by porous spherical carriers in a submerged membrane bioreactor

In this study, porous spherical carriers were fixed around the hollow fiber membrane module to mitigate membrane biofouling. Two MBRs (R1 without carriers, R2 with carriers) were operated for 31 days under identical operating conditions to investigate the effects of the carriers on the reactor performances, the production of extracellular polymeric substances (EPS), the level of N-acyl-homoserine lactones (AHLs), and the microbial communities. The results showed that the presence of carriers in MBR was conducive to nitrogen removal and decreased the total membrane filtration resistance by about 1.7 times. Slower transmembrane pressure (TMP) rise-up, thinner bio-cakes, lower EPS production, and fewer tryptophan and aromatic proteins substances on the membrane surface were observed in R2. The polysaccharides secretion of EPS in bio-cakes was mainly regulated by C4-HSL and 3OC6-HSL in the presence of carriers. The microbial community analysis revealed that carriers addition reduced the relative abundance of EPS and AHL producing bacteria in the membrane bio-cakes and enriched the accumulation of functional bacteria conducive to nutrient removal in the mixed liquor. This study provided an in-depth understanding for the application of porous spherical carriers to alleviate membrane biofouling.

Performance Investigation of a Hollow Fiber Membrane-Based Desiccant Liquid Air Dehumidification System

The membrane-based desiccant liquid air dehumidification system is a promising technology for efficient humidity control in buildings. The use of a membrane module allows, among other things, for a compact design with a relatively large heat and mass transfer area and eliminates carryover of solution droplets. In this paper, a cross-flow, hollow-fiber membrane module was proposed for air dehumidification and regeneration of lithium chloride. A two-dimensional heat and mass transfer model for cross-flow in a membrane module used for air dehumidification and liquid desiccant regeneration was developed. The effectiveness, moisture removal rate and moisture removal rate were studied numerically and validated against experimental results. Based on the numerical simulations, the most favorable ranges of operating conditions were determined. It was found that the operating conditions significantly impact the dehumidification performance. The proposed dehumidifier maintains its performance in a wide range of inlet air humidity ratios. For dehumidification, the recommended temperature of the incoming solution was in the range of 14–18 °C, while for regeneration the solution range was 40–50 °C. The packing fraction was suggested in the range of 0.30–0.40. These results can help design membrane-based liquid dehumidification systems.

Forward osmosis system design and optimization using a commercial cellulose triacetate hollow fibre membrane module for energy efficient desalination

This study is aimed at developing system mathematical design models to simulate and optimize a full scale forward osmosis (FO) for a hollow fibre membrane module for energy efficient desalination. Experimental data from a commercial outer selective CTA hollow fibre FO membrane module was used for validation. Less than 10% difference between the simulation and experimental results were observed which validated the reliability of the models. Simulation and design were performed for a 1000 m3/day FO plant using 0.6 M NaCl as draw solution (DS) (~seawater) and 0.02 M NaCl feed solution (FS) (~MBR effluent) to produce 0.25, 0.2 and 0.15 M NaCl diluted seawater to reduce the energy consumption of downstream pressure driven desalination process. A single element parallel module arrangement was found more suitable for this commercial hollow fibre membrane element. Finally, the numerical simulations revealed that to achieve 0.25, 0.20 and 0.15 M final DS concentrations, the optimum number of modules required were 370, 435 and 555 respectively considering membrane cost and energy consumption. The FO system using the commercial CTA hollow fibre module was found more energy efficient than a commercial TFC spiral wound membrane module.

MIL-88B(Fe)-coated photocatalytic membrane reactor with highly stable flux and phenol removal efficiency

• MIL-88B(Fe)@Al 2 O 3 was used for photocatalytic membrane reactors. • High flux and phenol removal efficiency were obtained using the photocatalytic membrane reactors. • The Fe-clusters of MIL-88B(Fe) acted as reactive sites for the photocatalytic reaction. In this study, MIL-88B(Fe) was successfully prepared and coated onto an Al 2 O 3 substrate. Two photocatalytic membrane reactors (PMRs) for phenol degradation were fabricated using the MIL-88B(Fe)-coated substrates. A coated substrate was either placed into a flat-sheet membrane module to give a photocatalytic flat-sheet membrane reactor (PFMR) or integrated with an Al 2 O 3 hollow fiber membrane module to produce a photocatalytic hollow fiber membrane reactor (PHMR). In the PHMR system, the phenol removal efficiency was significantly enhanced, and the permeate flux remained stable at over 4000 L m –2 h −1 bar −1 . The flux of the PFMR was approximately 80–100 L m –2 h −1 bar −1 ; this lower flux was attributed to the coating and full coverage of MIL-88B(Fe) on the Al 2 O 3 surface. These two systems exhibited recyclability, reusability, and stability over at least three cycles of photocatalytic phenol removal. Characterization of the samples after the reaction illustrated that the iron clusters, which act as the reactive sites, remained stable even though the terephthalate organic linkers were partially destroyed during the photocatalytic reaction. The PMRs developed in this study show promise as effective, feasible, and sustainable systems for wastewater treatment.

Comparison of Pressure-Retarded Osmosis Performance between Pilot-Scale Cellulose Triacetate Hollow-fiber and Polyamide Spiral-Wound Membrane Modules.

Pressure-retarded osmosis (PRO) has recently received attention because of its ability to generate power via an osmotic pressure gradient between two solutions with different salinities: high- and low-salinity water sources. In this study, PRO performance, using the two pilot-scale PRO membrane modules with different configurations—five-inch cellulose triacetate hollow-fiber membrane module (CTA-HF) and eight-inch polyamide spiral-wound membrane modules (PA-SW)—was evaluated by changing the draw solution (DS) concentration, applied hydrostatic pressure difference, and the flow rates of DS and feed solution (FS), to obtain the optimum operating conditions in PRO configuration. The maximum power density per unit membrane area of PA-SW at 0.6 M NaCl was 1.40 W/m2 and 2.03-fold higher than that of CTA-HF, due to the higher water permeability coefficient of PA-SW. In contrast, the maximum power density per unit volume of CTA-SW at 0.6 M NaCl was 4.67 kW/m3 and 6.87-fold higher than that of PA-SW. The value of CTA-HF increased to 13.61 kW/m3 at 1.2 M NaCl and was 12.0-fold higher than that of PA-SW because of the higher packing density of CTA-HF.