Spiral Wound Membrane Modules Research Articles

A review of spiral wound membrane modules and processes for groundwater treatment

A review of spiral wound membrane modules and processes for groundwater treatment

Integrated membrane process for pretreating and desolventizing hexane-soybean oil miscella – A pilot plant study

The study aimed to develop a membrane desolventizing technology for solvent recovery in vegetable oil extraction. Pretreatment of crude miscella is a prerequisite for an organic solvent nanofiltration (OSN) based desolventizing process. Solvent-resistant ultrafiltration (SRUF) membrane employed in micelle-enhanced ultrafiltration (MEUF) of hexane-crude soybean oil miscella displayed high phospholipids (PL) rejection (98.5%) and productivity (∼28 L/m2/h), accompanied with a moderate oil rejection (∼22%). The PL-rich retentate fraction was alkali-treated to recover the oil in the stream (8.8%). This complementary pretreatment approach met the quality requirements and maximized the yield of treated oil (>98%) while reducing the chemicals in the process. A subsequent two-stage desolventizing of MEUF-treated miscella with solvent-resistant nanofiltration (SRNF) membrane reduced the oil-in-permeate to 1.37%, achieving the set recycling criteria (<2%). The results obtained from the pilot scale study (batch size 40 kg of crude miscella) revealed that the MEUF met the pretreatment requirements, and the subsequent OSN process recovered ∼63% of hexane through a non-thermal route for recycling in the extraction process. The pilot-scale evaluation demonstrated the technical feasibility of the proposed membrane desolventizing process employing indigenous spiral-wound SRUF and SRNF membrane modules.

Large-Area Ultrathin Metal-Organic Framework Membranes Fabricated on Flexible Polymer Supports for Gas Separations.

Ultrathin continuous metal-organic framework (MOF) membranes have the potential to achieve high gas permeance and selectivity simultaneously for otherwise difficult gas separations, but with few exceptions for zeolitic-imidazolate frameworks (ZIF) membranes, current methods cannot conveniently realize practical large-area fabrication. Here, we propose a ligand back diffusion-assisted bipolymer-directed metal ion distribution strategy for preparing large-area ultrathin MOF membranes on flexible polymeric support layers. The bipolymer directs metal ions to form a cross-linked two-dimensional (2D) network with a uniform distribution of metal ions on support layers. Ligand back diffusion controls the feed of ligand molecules available for nuclei formation, resulting in the continuous growth of large-area ultrathin MOF membranes. We report the practical fabrication of three representative defect-free MOF membranes with areas larger than 2,400 cm2 and ultrathin selective layers (50‒130 nm), including ZIFs and carboxylate-linker MOFs. Among these, the ZIF-8 membrane displays high gas permeance of 3,979 GPU for C3H6, with good mixed gas selectivity (43.88 for C3H6/C3H8). To illustrate its scale-up practicality, MOF membranes were prepared and incorporated into spiral-wound membrane modules with an active area of 4,800 cm2. The ZIF-8 membrane module presents high gas permeance (3,930 GPU for C3H6) with acceptable ideal gas selectivity (37.45 for C3H6/C3H8).

Scalable nanofiltration membranes with sharpened pore distribution and enhanced negativity for mono/divalent anion separation

The petrochemical industry is an important producer of high salinity wastewater, necessitating the efficient separation of salts in zero discharge processes. This study reports the development of an industrially scalable thin film composite nanofiltration membranes that facilitate the effective separation of NaCl/Na2SO4. Employing a one-step functionalization process, the membrane pore distribution is sharpened, and the surface negativity is intensified. Branched polyethyleneimine with abundant reactive amine groups is employed as an aqueous co-monomer, leading to the generation of high density grafting active sites. Nucleophilic substitution reaction is employed to functionalize the membrane surface with negatively charged sulfonic acid groups. Simultaneously, large voids within the free volume are filled and the pore size distribution is effectively narrowed. The resultant membranes demonstrate an impressive rejection of 99.5 % for Na2SO4, a selectivity of 163.4 for NaCl/Na2SO4 and a selectivity of 488 for Cl−/SO42−, with a water flux of 45 LMH under 0.5 MPa. The corresponding 8″ × 40″ sized spiral wound membrane modules exhibit a NaCl/Na2SO4 selectivity of 100.4 and a Cl−/SO42− selectivity of 258.3, demonstrating high practical applicability. A pilot trial is planned to integrate these novel membrane products into zero discharge processes within the internal chemical enterprises of Sinopec.

Spiral-wound organic solvent membrane modules for dewaxing solvent recovery

The petrochemical industry is typically energy-intensive, involving frequent and intricate separation processes. SINOPEC is a globally recognized lubricant manufacturer and distributor, with a substantial production capacity exceeding 1.7 million tonnes in 2022. The dewaxing solvent recovery process in lubricant production necessitates a multi-stage flash and distillation treatment, resulting in substantial energy consumption and high costs. Utilizing organic solvent nanofiltration (OSN) membranes offers a feasible alternative approach to address this issue. A series of thin film composite OSN membranes with varying molecule weight cut-offs were prepared through precise adjustment of the chemical composition and proportion of the organic co-monomers. The application potential of the optimized membranes in the lubricant dewaxing solvent recovery was evaluated using lubricant base oil derived from the actual production line, specifically light deasphalted oil and vacuum cut2. The membrane exhibited a rejection of 99.3 % for light deasphalted oil and 95.6 % for vacuum cut2, with corresponding fluxes of 16.8 and 13.4 LMH under 2 MPa, respectively. Based on this, spiral-wound membrane modules (1.8″ × 12″) were fabricated and their suitability for dewaxing solvent recovery was further validated. The fabrication of spiral-wound membrane modules (8″ × 40″) is in progress, with intentions to conduct a pilot plant trial on the lubricant oil manufacturing line.

A comprehensive evaluation of the temporal and spatial fouling characteristics of RO membranes in a full-scale seawater desalination plant

The fouling of seawater reverse osmosis (SWRO) membranes remains a persistent challenge in desalination. Previous research has focused mainly on fouling separately; however, organic, inorganic, and biofouling can coexist and influence each other. Hence, in-depth study of the spatiotemporal changes in actual combined fouling in full-scale seawater desalination will provide more effective information for fouling investigation and control. In this study, we monitored (i) the operational performance of a full-scale desalination plant for 7 years and (ii) the development and characterization of membrane and spacer fouling at different locations of spiral-wound membrane modules sampled after 2.5-, 3.5-, and 7-year operation. The findings showed that (i) operational performance indicators declined with time (normalized flux 40 % reduction, salt rejection 2 % in 7 years), with a limited effect of the 20-day cleaning frequency, (ii) fouling accumulation in the membrane module mainly occurred at the feed side of the lead module and the microbial community in these area exhibited the highest diversity, (iii) the dominant microbial OTUs belonged mainly to Proteobacteria (43–70 %), followed by Bacteroidetes (10–11 %), (iv) Phylogenetic molecular ecological networks and Spearman correlation analysis revealed that Chloroflexi (Anaerolineae) and Planctomycetes were keystone species in maintaining the community structure and biofilm maturation and significantly impacted the foulant content on the SWRO membrane, even with low abundance, and that (v) fouling accumulation was composed of polysaccharides, soluble microbial products, marine humic acid-like substances, and inorganic Ca/Fe/Mg/Si dominate the fouling layer of both the membrane and spacer. Overall, variation partitioning analysis quantitatively describes the increasing contribution of biofouling over time. Ultimately, the organic‒inorganic-biofouling interaction (70 %) significantly contributed to the overall fouling of the membrane after 7 years of operation. These results can be used to develop more targeted fouling control strategies to optimize SWRO desalination plant design and operation.

Impact of SWMM Fouling and Position on the Performance of SWRO Systems in Operating Conditions of Minimum SEC.

Due to water stress in the world in general desalination technologies are becoming increasingly important. Among the available technologies, reverse osmosis (RO) is the most widespread due to its reliability and efficiency compared to other technologies. The main weakness of RO is the loss of performance due to membrane fouling, which usually affects the water permeability coefficient (A), causing it to decrease. In RO desalination plants, fouling does not affect all spiral wound membrane modules (SWMMs) in the pressure vessels (PVs) in the same way. This will depend on the type of fouling and the position of the SWMM inside the PV. In this study, the impact of A and the position of the SWMM on the performance of the RO system is analyzed. For this purpose, decrements of up to 50% have been assumed for the seven SWMMs in series considering nine commercial SWMM models. The operating point analyzed is that which minimizes the specific energy consumption (SEC), a point obtained in a previous work carried out by the authors. The results show how the impact of A on the SWMM in the first position is more significant than the impact on modules that are in another position for the nine SWRO models studied. A drop of 50% in the coefficient A of the first element produces a permeate loss in the pressure pipe between 0.67 and 1.35 m3 d-1. Furthermore, it was observed that the models with the lowest coefficient A exhibited the highest performance losses in terms of permeate production when A was decreased.

Role of permeability coefficients in salinity gradient energy generation by PRO systems with spiral wound membrane modules

Processes that can transform a salinity gradient into electrical energy have gained attention in recent years. One such process, which uses semipermeable membranes to generate electrical energy through a turbine, is pressure retarded osmosis (PRO). As a potential renewable energy technology, this process could also be integrated in desalination plants to reduce the energy consumption. However, principally because of certain drawbacks concerning membrane and module characteristics, PRO technology has not yet been fully exploited at commercial scale. This study aims to assess the impact of membrane permeability coefficients on the energy generated by full-scale single-stage PRO systems. This allow an evaluation of the performance of PRO modules in series considering variation of the permeability coefficients that may be due to the impact of fouling. An evaluation was made of the HTI OsMem™ 2521 spiral wound membrane module considering a diameter of 8 inches (high up-scaled active area) and different permeability coefficient ranges. The results showed that a 50% water permeability coefficient decrease would produce an approximately 25% decrease in the amount of energy that could be generated, while a 50% increase in the solute permeability coefficient would have virtually no effect when considering optimal operating points. Variation of the water permeability coefficient had more impact on the potential amount of generated energy than variation of the solute permeability coefficient.

Evaluation of Commercial RO Membrane for BaCl2 Separation

The conventional methods of the BaCl2 solution separation are characterized by high energy consumption, reagent requirement, and other technological limitations. The pressure-driven membrane process can be an alternative, but the number of published investigations in this field is limited. The study of the effectivity of the BaCl2 diluted solution separation using the commercially available reverse osmosis membrane was carried out. It was defined that the spiral wound membrane module HID TFC 1812-75 GPD (nominal permeate flux is 281 l/d) has acceptable characteristics of productivity and selectivity. In particular, the permeate flux through these membranes for the BaCl2 solutions does not differ from the fluxes for other salt solutions in the considered range of the applied pressures (0.2-0.6 MPa). The rejection coefficient values were in the range of 0.9-0.95 and slightly varied with applied pressure. Therefore, such membranes are suitable for wastewater purification from the remains of BaCl2. At the same time, the concentration ratio does not exceed 1.5-2, consequently, the application of such membranes on the concentration stage requires deeper justification based on the economical parameters. The significant influence of the concentration polarization on the separation effectivity was not detected up to applied pressures 0.5 MPa.

Performance of Hypersaline Brine Desalination Using Spiral Wound Membrane: A Parametric Study.

Desalination of hypersaline brine is known as one of the methods to cope with the rising global concern on brine disposal in high-salinity water treatment. However, the main problem of hypersaline brine desalination is the high energy usage resulting from the high operating pressure. In this work, we carried out a parametric analysis on a spiral wound membrane (SWM) module to predict the performance of hypersaline brine desalination, in terms of mass transfer and specific energy consumption (SEC). Our analysis shows that at a low inlet pressure of 65 bar, a significantly higher SEC is observed for high feed concentration of brine water compared with seawater (i.e., 0.08 vs. 0.035) due to the very low process recovery ratio (i.e., 1%). Hence, an inlet pressure of at least 75 bar is recommended to minimise energy consumption. A higher feed velocity is also preferred due to its larger productivity when compared with a slightly higher energy requirement. This study found that the SEC reduction is greatly affected by the pressure recovery and the pump efficiencies for brine desalination using SWM, and employing them with high efficiencies (ηR ≥ 95% and ηpump ≥ 50%) can reduce SEC by at least 33% while showing a comparable SEC with SWRO desalination (<5.5 kWh/m3).

Industrial-scale spiral-wound facilitated transport membrane modules for post-combustion CO2 capture: Development, investigation and optimization

Membrane separation technology is one of the most promising strategies for post-combustion CO2 capture. The high-performance membrane module is one of the most critical components in the CO2 capture membrane system. The spiral-wound module is a promising type for industrial application; however, most of the research remains in the laboratory. In this work, industrial-scale spiral-wound membrane modules containing facilitated transport membranes have been developed and investigated. Under given practical operating conditions, an apparent gas separation performance was defined as an indicator to study the effects of various feed conditions on membrane performance within the module. As a crucial process parameter, the operating pressure was considered a variable to investigate the module performance at a fixed feed-to-permeate pressure ratio, and techno-economic indicators were also studied. Furthermore, a multi-core module containing up to 14 membrane elements was designed based on the experimental results of the arrangement mode cases. This work could bridge the research gap between membrane development and membrane system engineering. It could also provide essential data for the industrial application of post-combustion CO2 capture.

Antimicrobial and Antibiofouling Electrically Conducting Laser‐Induced Graphene Spacers in Reverse Osmosis Membrane Modules

AbstractBiofouling is an ongoing challenge for water treatment membrane processes. Reducing biofilm growth on the membrane surface or on the polymeric feed spacer will reduce operation, maintenance, and module replacement costs. Laser‐induced graphene (LIG) is a low cost, environmentally friendly, electrically conductive carbon material shown to have antibiofouling properties. Here it has been shown that an electrically conductive LIG‐coated polypropylene (PP) feed spacer has both antimicrobial and antifouling effects under a low electrical current, and when implemented into a spiral wound membrane module reduced biofilm growth on both the membrane and the spacer components. The antibacterial property of the LIG spacer is tested using Pseudomonas aeruginosa and the brackish water Rheinheimera sp. as model organisms. Using a voltage of 12 V, P. aeruginosa is completely inactivated in 10 h, while a dynamic accumulation assay employing Rheinheimera sp. showed significant reduction (p &lt; 0.05) in bacterial adhesion compared to an uncoated spacer. The spacer is incorporated into a spiral wound reverse osmosis (RO) membrane module, and reduced biofouling is observed on both the membrane and LIG spacers components using brackish water and 12 V. This study demonstrates the feasibility of electrically conductive feed spacer components in spiral wound RO membrane modules.

Simulation tool for full-scale PRO systems using SWMMs

Pressure retarded osmosis (PRO) is a process that is able to convert a salinity gradient into electrical energy through a turbine. This process has gained attention as a possible renewable energy technology for integration into desalination plants to improve their energy efficiency. Despite recent efforts, PRO is not yet commercially available due to drawbacks related to, among others, PRO membrane and module development. The aim of this study is to provide a simulation tool for full-scale PRO systems that allows accurate estimates of PRO-related energy generation to be made. The proposed tool enables analysis of single-stage systems with PRO modules in series and the setting of boundary conditions per module in terms of maximum flux recovery, and maximum and minimum feed/draw flow. The HTI OsMem™ 2521 spiral wound membrane module (SWMM) was evaluated considering an 8 in. diameter (high active area). Increasing the number of SWMMs in series was found to increase permeate flow and the energy that can be generated, even when considering the pressure drop on both draw and feed side and the effect of the dilution and concentration of the draw and feed solutions. The proposed tool allows to determine the safe operating windows and operating points for maximization of energy generation for fixed and variable operating conditions.

Gas/liquid two-phase flow with perforated hollow filament spacer to enhance the filtration performance in spiral wound membrane module

In brackish water and seawater desalination process, flat sheet and spiral wound membrane modules are commonly used to remove particulate pollutants and/or inorganic ions. In these membrane modules, feed spacer is used to construct the flow channel, enhance the flow field and corresponding filtration performance. However, two negative effects also occur for the spacer. One is the high pressure drop due to flow around the filament. The other is the stagnant zone near the filament, which results in localized fouling. In this paper, a new perforated hollow filament spacer was proposed. Gas/liquid two-phase flow was used to mitigate the membrane fouling. Filtration experiments were performed by microfiltration of SiC suspension. Results showed that compared with conventional spacer, the hollow filament spacer can improve the steady permeate flux by 56 %, with lower pressure drop. Particle deposition on membrane surface was effectively retarded, without localized fouling observed. Gas/liquid Flow patterns in the membrane channel were studied with high-speed photography. With the increase of Gas/liquid ratio, the flow pattern changes from bubble flow, slug flow to churn flow. The best filtration improvement performance was obtained with slug flow pattern. This hollow filament spacer is expected to mitigate the membrane fouling and improve permeate flux in the membrane-based desalination process.

Arch-type feed spacer with wide passage node design for spiral-wound membrane filtration with reduced energy cost

A novel feed spacer for spiral-wound membrane modules is proposed. Based upon a continuous arch-type streamline frame two feed spacers with different node designs were constructed. In the first, Arch-Hole, two elliptic cylinders form a node zone with a passage. The other, named Arch, has a solid node. Their hydrodynamics, fouling and filtration performance were compared with a commercial design. This was a classic net-type spacer with nodes of relatively substantial size. All three were manufactured using 3D printing. Computational fluid dynamics simulation showed that the Arch-Hole design gives a more uniform velocity distribution with fewer dead zones. Subsequent evaluation of this design indicated less foulant accumulation as confirmed by optical coherence tomography and the evolution of channel pressure drop. Measured adenosine triphosphate and total organic carbon values for the module with this spacer were substantially lower than the corresponding values associated with the commercial design. Crucially with the Arch-Hole design, flux values remained higher than for the other two designs. Thus use of this spacer would minimize both capital and operational costs. Compared to the commercial one, use of the Arch-Hole design would reduce the energy cost of filtration significantly beyond the 69 % found for the application considered herein.

Modeling and multi-objective optimization of parameters in fabrication and performance analysis of polyvinylidene fluoride spiral-wound membrane modules

Modeling and multi-objective optimization of parameters in fabrication and performance analysis of polyvinylidene fluoride spiral-wound membrane modules

The critical role of feed spacer channel porosity in membrane biofouling: Insights and implications

Membrane biofouling is a major hindrance limiting the efficiency of spiral wound membrane (SWM) module for water treatment. Feed spacer is an imperative component of SWM module which creates feed channels, determines fluid field and thus influences biofilm development via its geometry. Yet, the role of feed spacer channel porosity in biofilm development remains unclear. In this study, 16 feed spacers of varied geometric parameters and thus different channel porosities were used for both numerical simulations and biofouling experiments. Results showed that the hydraulic and anti-biofouling performances were more sensitive to the variation of filament diameter and spacer thickness. Feed channel porosity as a gross parameter played a pivotal role in biofouling development. The high-porosity (> 0.85) feed spacer channels exhibited a slower increase of feed channel pressure drop when biofouling occurred, but with more biomass accumulated in the middle of spacer meshes because of lower shear stress. For the low-porosity (< 0.75) channels, biofilm incipiently developed from the interspace region between spacer filaments and membrane surface due to “block effect”, which aggravated “narrow channeling” and induced a larger area of dead zone, leading to more severe biofouling ultimately. An appropriate channel porosity was suggested at ∼0.85 based on the hydraulic and anti-biofouling performances conjointly in this study.

Simulation-based assessment of safe operating windows and optimization in full-scale seawater reverse osmosis systems

Reverse osmosis (RO) is the most widely used desalination technology for both seawater and brackish water. Unfortunately, RO remains an energy intensive technology despite the efforts being made to overcome this drawback. One of the factors that could help to minimize this issue is the optimal design and operation of RO systems. Membrane manufacturers are continuously improving and releasing new spiral wound membrane modules (SWMMs) that nonetheless need to be studied in order to determine how to achieve the best highest possible performance from them. The aim of this study was to evaluate the safe operating windows (SOWs) of 9 commercial SWMMs in pressure vessels (PVs) with 7 of these elements in a single stage seawater reverse osmosis (SWRO) system. The permeability coefficients of the SWMMs were taken from a novel membrane open database. These coefficients and the characteristics of the SWMMs were introduced in a simulation algorithm to estimate the behavior of the SWRO system. SOWs were determined without considering any energy recovery device, although these were considered for the calculation of the minimum energy consumption. The SWMMs were compared and the optimal operating points were identified for each one. The results showed the highest difference was around 0.2 kWhm−3 between SWMMs in their optimal operating point with respect to the minimum specific energy consumption. It was also found that this difference increases slightly with rises in feedwater concentration. For a wide range of PV power inputs, the SWMMs were able to reach quite similar maximum flux recovery rates. Experimental work is needed to obtain more reliable predictions of SWRO systems working in wide operating ranges.

3D CFD study of hydrodynamics and mass transfer phenomena for spiral wound membrane submerged-type feed spacer with different node geometries and sizes

Modification of the spacer geometry is a promising approach to increase the efficiency of reverse osmosis (RO) spiral wound membrane modules. Column nodes and spherical nodes are considered in this three-dimensional computational fluid dynamic (CFD) study to evaluate the hydrodynamic and mass transfer performance of submerged spacers with different node geometries and sizes. Small-scale CFD analysis results reveal that the column node has better mass transfer performance than the spherical node geometry because column nodes divert more flow to the filaments, leading to higher local velocity at the region between the filament and wall. Furthermore, when the dimensionless node diameter ratio of the column nodes increases from 0.3 to 1.2, Sherwood number and wall shear increase by 25% and 8% respectively at the expense of higher global friction factor (44%). A sea water RO full-scale analysis revealed that column node spacers yield higher average flux than spherical nodes and conventional spacers at high feed inlet velocity (> 0.1 m/s), because the mixing effects by the spacer that improve mass transfer are more prominent.

Predicting the performance of spiral-wound membranes in pressure-retarded osmosis processes

A process simulator has been developed to model and predict the performance of spiral-wound membrane modules in pressure retarded osmosis processes. This has involved automation of generalized protocols for the numerical integration of the solvent and solute flux equations (in conjunction with a suitable electrolyte equation of state) along the surface area of a spiral-wound membrane leaf. Performance equations are solved for discrete area elements and the spiral-wound character of the module as a whole is realized through the programmed sequence in which discrete elements are evaluated. This arrangement allows for mirroring the parabolic flow pattern of the feed stream in the spiral-wound membrane leaf. The total permeation (and, by extension, power density) is thus calculated in a manner that accounts for the driving force profile consistent with flow patterns specific to spiral-wound membranes. This effective treatment of each discrete element as a flat-sheet membrane enables the transferability of membrane parameters characterized in standard, coupon-scale experiments to the simulation of spiral-wound modules. This transferability is illustrated through comparisons of model predictions with published pilot-scale PRO data.