Types Of Fouling Research Articles

An integration of photo-Fenton and membrane process for water treatment by a PVDF@CuFe2O4 catalytic membrane

Membrane fouling always decreases the separation efficiency and shortens the membrane life, which severely hinders the practical application of the membrane technology. The photo-Fenton process can degrade various foulants with the generation of hydroxyl radicals, and its integration with membrane filtration may become an efficient way to improve the antifouling property and filtration performance of the membrane. In this study, the CuFe2O4 particles were synthesized and doped in the PVDF@CuFe2O4 membranes with increasing concentration from 0% to 1.0%. The degradation measurement of methylene blue (MB) solution shows the optimal conditions for the photo-Fenton process as CuFe2O4 concentration of 1.0%, pH of 3.0, and H2O2 dosage of 400 μL. With the photo-Fenton cleaning process, the PVDF@CuFe2O4 membrane (1.0%) exhibits versatile antifouling property to different types of foulants, including organic dyes (e.g. MB and rhodamine B (RhB)), nature organic matter (e.g. humic acid (HA)), and protein (e.g. bovine serum albumin (BSA)). With the integration of photo-Fenton and membrane process, the PVDF@CuFe2O4 membrane (1.0% of CuFe2O4) dramatically enhanced the separation efficiency, with the results of 99.77% to MB, 81.02% to RhB, 36.35% to HA, and 82.94% to BSA. The flux and rejection have been increased respectively to threefold and double of the corresponding data from the membrane filtration alone. Moreover, even after fifteen cycles of experiments, the average MB rejection is still higher than 70%, which further indicates the good stability and reusability of the PVDF@CuFe2O4 membrane. Therefore, this study provides a promising methodology for the successful fabrication of high-performance membrane through the integration of photo-Fenton and membrane process, and further proposes a new strategy on the design and application of functional materials for new generation of catalytic membranes.

Critical flux-based membrane fouling control of forward osmosis: Behavior, sustainability, and reversibility

Membrane fouling is closely related to the concept of critical flux. Therefore, a fouling control strategy for forward osmosis (FO) membranes that is based on the critical flux is necessary. This study systematically investigated the critical flux behavior of FO membranes (CTA and PA-TFC) in the short-term using a stepping method (draw solution (DS) concentration stepping). In addition, to test the reliability of this method, long-term experiments were conducted to evaluate the influences of operational critical flux on the fouling behavior (sustainable operation and fouling reversibility/irreversibility), thereby determining the critical flux for reversibility. Our results showed that the DS concentration stepping could be applied for critical flux determination in FO. Both membranes exhibited higher critical flux values for alginate fouling compared to other single foulants such as colloidal silica or gypsum. The values were 15.9 LMH for a cellulose triacetate membrane (CTA) and 20.5 LMH for the polyamide thin-film composite (PA-TFC). Whilst these values should be adequate in FO applications they were determined for single foulants. The presence of multispecies of foulants caused a significant decline in the critical flux values. This study found 5.4 LMH for the CTA membrane and 8.3 LMH for the PA-TFC membrane for the combined foulants of alginate + gypsum. This indicates that the critical flux behavior in FO was dependent on the foulant type and membrane type. Importantly, the high restoration of water flux was achieved with the PA-TFC membrane at an operation either close to critical flux (92–98%) or below critical flux (98–100%) (i.e., with negligible irreversible fouling). The critical fluxes for reversibility obtained in this study will aid the efficient operation of practical FO processes.

Interplay between physical cleaning, membrane pore size and fluid rheology during the evolution of fouling in membrane bioreactors

Fouling is one of the most pressing limitations during operation of membrane bioreactors, as it increases operating costs and is the cause of short membrane lifespans. Conducting effective physical cleanings is thus essential for keeping membrane operation above viable performance limits. The nature of organic foulants present in the sludge and the membrane properties are among the most influential factors determining fouling development and thus, efficiency of fouling mitigation approaches. The role of other factors like sludge viscosity on fouling is still unclear, given that contradictory effects have been reported in the literature. In the present study we use a new research approach by which the complex interplay between fouling type, levels of permeate flux, membrane material and feed properties is analyzed, and the influence of these factors on critical flux and membrane permeability is evaluated. A variety of systems including activated sludge and model solutions with distinct rheological behavior has been investigated for two membranes differing in pore size distribution. We present a novel method for assessing the efficiency of fouling removal by backwash and compare it with the efficiency achieved by means of relaxation. Results obtained have proven that backwash delays development of critical fouling as compared with relaxation and reduces fouling irreversibility regardless of fluid rheology. It was shown that backwash is especially effective for membranes for which internal fouling is the main cause of loss in permeability. Nonetheless, we found out that for membranes with tight pores, both relaxation and backwash are equally effective. The critical flux decreases significantly for high-viscosity fluids, such as activated sludge. This effect is mainly caused by an intensified concentration polarization at the feed side rather than by internal fouling events. However, membrane permeability has been proven to rely more on the permeate viscosity than on the feed viscosity: poor rejection of organic fractions showcasing high viscosity causes an acute decline in membrane permeability as a consequence of increased shear stress inside the membrane pores.

The Effect of Concentration Staging on Performance of Produced Water treatment using Forward Osmosis

During oil and gas production, a large amount of produced water (PW) is generated, which would be harmful to the environment if not treated properly. Treatment of such wastewater requires multi-processing units and typically includes fouling prone pressure driven membranes. Forward osmosis (FO) seems promising due to its high salt rejection, high total dissolved solid removal, more reversible fouling type, does not require external pressure to operate and potentially can be used as a standalone unit with minimum pretreatment. However, FO still suffers from low permeate flux, high reverse solute flux (RSF) and membrane fouling, although not as severe as in pressure driven membrane. Since FO depends largely on osmotic pressure difference, the effect of concentration staging was investigated. It was found that multi-stage concentration was able to achieve up to 80% water recovery due to sufficient osmotic pressure.

Treatment of Palm Oil Mill Effluent Using Membrane Bioreactor: Novel Processes and Their Major Drawbacks

Over the years, different types of alternative technologies have been developed and used for palm oil mill effluent (POME) treatment. Specifically, membrane bioreactor (MBR) has been employed to relegate pollutants contained in POME under different operating conditions, and the technology was found to be promising. The major challenge impeding the wider application of this technology is membrane fouling, which usually attracts high operating energy and running cost. In this regard, novel methods of mitigating membrane fouling through the treatment processes have been developed. Therefore, this review article specifically focuses on the recent treatment processes of POME using MBR, with particular emphasis on innovative processes conditions such as aerobic, anaerobic, and hybrid processing as well as their performance in relation to fouling minimization. Furthermore, the effects of sonication and thermophilic and mesophilic conditions on membrane blockage were critically reviewed. The types of foulants and fouling mechanism as influenced by different operating conditions were also analyzed censoriously.

Non-destructive approaches for assessing biofouling of household reverse osmosis membranes

This study determined economic non-destructive methods to assess biofouling in point of use reverse osmosis (RO) membrane treatment systems. Three parallel household RO membrane units were operated under controlled feed water conditions to promote biofouling, inorganic fouling and a combination of both. Operational and biological parameters were monitored throughout the systems’ lifespan. Membrane autopsies assessed the degree and type of fouling. Statistical models determined statistically relevant parameters for fouling types that were validated with membrane autopsies. Permeate flow rates decreased differently with biofouling vs inorganic fouling. Large increases in permeate conductivity were noted in membranes suffering from biofouling and not in inorganically fouled membranes. The concentration of cell clumps from detached biofilm in the retentate increased in membranes experiencing biofouling and no increase was seen for inorganically fouled membranes. A combination of these methods could be used to conveniently assess the types of fouling experienced by RO systems.

Using Time Domain Reflectometry to Determine Depth of Fouling and Fouling Type in Railway Track Substructure

Abstract This study documents the development of a procedure for the identification of the depth and type of ballast fouling using the time domain reflectometry (TDR) technique. Ballast fouling leads to a reduction in the bearing capacity of the railway substructure, a decrease in the drainage capacity, and an increase in track deformation. As a consequence of these detrimental effects, rail tracks lose load capacity, ride comfort deteriorates, and trains may ultimately derail. The determination of type and extent of ballast fouling may be used to assess the expected life of rail track and to plan maintenance operations. TDR waveforms of variably fouled ballast and subballast layers were evaluated in the lab to yield relative dielectric permittivity and electrical conductivity and to thus characterize the effect of ballast gradation, mineralogy, and water content on electromagnetic response. Strong relationships between depth of fouling, volumetric water content, and relative dielectric permittivity were developed. These results were then expanded to the interpretation of ground penetrating radar (GPR) inspection and to quantify the level of fouling in larger-scale maintenance operations. The proposed technique can be complementary to GPR as it reduces the uncertainty in determining the depth and type of fouling when using GPR alone.

Application of membrane distillation for the treatment of anaerobic membrane bioreactor effluent: An especial attention to the operating conditions

This study was carried out by applying the direct contact membrane distillation (DCMD) into the treatment of effluent from anaerobic membrane bioreactor. The treatment efficiency of DCMD was highly emphasized, which was expected to be improved through the optimization of operating conditions. Three operating conditions, including temperature difference, cross-flow velocity and membrane pore size, were considered. The relative flux (the ratio of actual flux to initial flux) increased from 0.50 to 0.98 as the operating conditions changed and that was enhanced by the increment of temperature difference and cross-flow velocity. Regarding the wastewater treatment efficiency, except for ammonia nitrogen, the interception ratio was greater than 90.0%, which even reached 99.0% for CODCr, protein and polysaccharide by optimizing operating conditions. In addition, the interception ratio of PO43--P almost reached 100.0% under any operating condition. Further study about membrane fouling was carried out, and the crystallization fouling was found to be the main fouling type.

Comparison of fouling propensity between reverse osmosis, forward osmosis, and membrane distillation

Resistance to fouling is often cited as an advantage of emerging desalination technologies such as forward osmosis and membrane distillation over the widely-used reverse osmosis process. However, the nature and magnitude of differences in fouling behavior between these three processes are not well characterized. This study directly compares the fouling and scaling behavior of reverse osmosis (RO), forward osmosis (FO), and direct contact membrane distillation (MD) in the same membrane module under identical hydrodynamic conditions (flux and cross-flow velocity). Fouling experiments were conducted using calcium sulfate as a model inorganic foulant and alginate as a model organic foulant. Although all three processes tolerated some degree of feed supersaturation for 36 h without inorganic fouling (scaling), FO exhibited the greatest scaling resistance, withstanding a feed of 33± 2 mM CaSO4 (approximately twice saturation) without significant flux decline. Scaling occurred at similar concentrations at the membrane between MD and RO; however, while MD tolerated a more concentrated bulk feed due to reduced concentration polarization, flux decline after fouling was considerably more severe in MD. In contrast, MD tolerated organic fouling much better than FO or RO: despite accumulating a similar quantity of alginate gel over 18 h of operation, flux declined only 14% in MD versus 46–47% in RO and FO. These results are explained with respect to differences in temperature, membrane materials, and transport mechanisms between the three processes. Although FO and MD each exhibited superior resistance to one type of foulant, neither process outperformed RO in resistance to both organic and inorganic fouling. These findings inform a more nuanced approach to process selection for the treatment of complex water sources.

Relationship between scouring efficiency and overall concentration of fluidized granular activated carbon (GAC) in microfiltration

The use of liquid–solid fluidization as a means of membrane fouling mitigation has aroused increasing attention especially in membrane bioreactors. Past studies have affirmed a relationship between the fluidized GAC media and fouling trends, and also shed light on the effects of superficial liquid velocity, power requirement, GAC particle diameter and foulant type on the effectiveness of fouling mitigation during microfiltration. In particular, the ratios of the local critical flux to the overall critical flux (Jc,local/Jc,overall) were shown to deviate from unity, owing to different expanded bed heights of the fluidized GAC and causes non-uniform fouling across the membrane. Accordingly, this study was aimed at understanding the impact of different overall GAC concentrations, which give different expanded bed heights, on the extent of fouling mitigation. Monodisperse millimeter-sized GAC were used as the fluidized media and the particulate foulants were micrometer-sized polystyrene and bentonite particles. The results indicate that the highest overall concentration was advantageous in terms of enabling (i) higher membrane fouling mitigation at a lower power required per unit permeate (Pp) for the polystyrene foulant but not bentonite foulant; and (ii) more similar Jc,local values over the three heights investigated, which implies more uniform fouling mitigation across the membrane. The relative benefits of adjusting overall GAC concentration versus the particle diameter of the GAC media were also critically assessed.

Searching for ultrafiltration membrane molecular weight cut-off for water treatment in recirculating aquaculture system

Ultrafiltration (UF) has been proposed as a promising technology in recirculating aquaculture systems (RAS) to remove both organic contaminants and other fine contaminants including viruses and pathogenic bacteria. However, fouling is still a severe problem during this application. This paper investigated the fouling behavior of three different UF membranes examined using five different aquaculture contaminants. The experiments were performed using UF membranes with molecular weight cut-off 10, 50, and 100 kDa. Humic acid, shrimp feed, Spirulina sp., Vibrio harveyi and IHHNV were used as contaminant models. Scanning electron microscope was used to visualize the presence of foulant on the membrane surface. The results showed that fouling behavior was affected by both membrane cut-off (pore size) and foulant type. Two fouling behaviors were observed: (i) rapid flux decline at the early stage of filtration followed by relatively constant permeate flux until experiments finished, and (ii) rapid flux decline at the early stage of filtration followed by a gradual decrease in permeate flux. Due to its reliable flux value and high rejection, 100 kDa UF membrane should be considered as the most suitable UF membrane for RAS application.

Effects of organic, biological and colloidal fouling on the removal of pharmaceuticals and personal care products by nanofiltration and reverse osmosis membranes

The impact of different foulant composition and pHs on the removal of pharmaceutical and personal care products (PPCPs) by nanofiltration (NF270 and NF90) and reverse osmosis (XLE) membranes was investigated in this study. Humic acid (HA), alginate (SA) and silica (Si) were used for the formation of organic, biological and colloidal fouling, respectively, and were further mixed for the formation of composite fouling on membrane surfaces. The results show that significant flux decline was observed with decreasing pH and all kinds of foulant composition for the three membranes, which was contributed mostly by irreversible fouling, especially for the tight XLE. Moreover, the trends of flux decline and particle size of composite foulants at different pHs were dominant by HA for all membranes, implying that the control of organic matrix in water before reaching NF/RO process is crucial to the performance of membrane filtration. On the other hand, all types of membrane fouling caused the decrease of PPCP rejection by NF270, especially for the hydrophilic-ionized and hydrophobic-ionized compounds at low pHs because of the shield of dominant electrostatic repulsion mechanism between PPCPs and membrane surface, causing the cake-enhanced concentration polarization phenomenon. The results were verified by dense and thick cake layers observed using scanning electron microscopy, the corresponding change of contact angles, and high adsorption amount of very hydrophobic triclosan on the active layer of NF270. However, steric hindrance and electrostatic repulsion worked synergistically for the increasing PPCP rejection by NF90 with increasing pH and membrane fouling, while steric hindrance dominates PPCP rejection by XLE. Therefore, one order less triclosan adsorption happened on membrane surface and the fouling layer of NF90 and XLE. The fouling mechanisms were illustrated using the modified Hermia model as gel layer formation for the loose NF270, intermediate blocking for NF90 and complete blocking for XLE.

Pressure-retarded osmosis with wastewater concentrate feed: Fouling process considerations

Pressure-retarded osmosis (PRO) has attracted worldwide attention for its potential applications in renewable osmotic energy harvesting, low energy seawater desalination, and industrial waste brine disposal. However, membrane fouling is one of the major issues limiting PRO performance with the use of a high-salinity draw solution and a low-value impaired feedwater. This study systematically investigated membrane fouling in the PRO process using a real wastewater retentate (a waste byproduct from wastewater reclamation plants) as the PRO feed. Organic fouling (e.g., by humic substances) and inorganic fouling (e.g., by calcium phosphate) were identified to be the major types of fouling, where the latter dominated the overall water-flux decline. The internal PRO membrane fouling was exacerbated by internal concentration polarization (ICP) and intermolecular interactions between the organic macromolecules and the scaling precursor ions (e.g., Ca2+). A limiting flux that was independent of the initial flux (i.e., applied pressure) was observed during the PRO fouling and was explained by a novel PRO limiting flux model. A membrane with a smaller structural parameter could achieve a higher limiting flux in PRO. A simple and effective pressure-assisted osmotic backwashing protocol was developed to clean the internally fouled membrane that could restore over 92% of the water flux within a short cleaning period (15mins). The PRO performance could also be significantly improved by decreasing the feedwater pH that mitigated alkaline scaling. Finally, performing the PRO membrane fouling test in the active-layer-facing-feed-solution (AL-FS) orientation revealed that the integral cellulose triacetate (CTA) membrane exhibited strong mechanical stability and anti-fouling tendency whereas the thin-film composite (TFC) membrane was not mechanically stable in this orientation. This study for the first time identified that an integral membrane instead of a TFC membrane is an excellent candidate for PRO operation in the AL-FS mode for fouling control.

A coupled finite volume & discrete element method to examine particulate foulant transport in metal foam heat exchangers

The exorbitant costs associated with particulate fouling necessitates the need to formulate advanced methods to comprehend mass transport and fouling in heat exchangers. A coupled finite volume and discrete element method is developed to investigate the mechanisms that govern particle-laden gas flows and particulate fouling in idealized porous metal foam heat exchangers. This meticulous examination will take great precedence in addressing the negative impact particulate fouling has in the industry. The numerical method will permit engineers to better optimize porous metal foams for applications such as air-cooled heat aluminium heat exchangers. The robustness of this numerical method is validated against the original and modified Darcy-Forchheimer analytical equations through a novel modified porosity theory. Good agreement is obtained between the numerical and analytical results. It is shown that both 2D and 3D heat exchanger configurations of identical porosities with different geometric profiles have shown similar deposition fraction and pressure drop magnitudes albeit having a slightly different fouling layer distribution. This is attributable to the particle properties and the variation between the 2D and 3D inlet injection plane surface area. It is found that the commencement of sandstone and sawdust deposition in a 6-pore configuration differs by 0.57s, whereas a three pore configuration completely nullifies particulate fouling irrespective of foulant type. A staggered row configuration has shown significant reduction in pressure drop as compared to the 6-pore heat exchanger configuration. For the case of sandstone particles, the optimum heat exchanger geometry exhibits 78% less pressure drop and 100% less deposition fraction compared with the original 6-pore configuration.

Fabrication of antifouling reverse osmosis membranes by incorporating zwitterionic colloids nanoparticles for brackish water desalination

Antifouling is important for RO membranes. Taking advantage of the reaction between hydroxyl groups on zwitterionic colloid nanoparticles (ZCPs) and acyl chloride group, ZCPs with tuned chemical structures were added into m-phenylenediamine aqueous solution to prepare thin-film nanocomposite membranes (ZPMs) via interfacial polymerization in this study. The incorporation of ZCPs tailored the membrane surface morphology and chemical properties, which were characterized by SEM, AFM, WCA, FTIR and XPS. Meanwhile, the effect on RO membranes separation and antifouling performances were systematically evaluated. In comparison with pristine membranes, the values of WCA decreased which means the hydrophilicity of membranes surface enhanced due to the existence of ZCPs, endowing the membrane with advanced water flux (37.3L·m−2·h−1) when operate with 2000ppm NaCl aqueous solution at 25°C under 1.5MPa. In order to evaluate the antifouling properties, the filtration with different types of model foulants were operated. When feed solution containing tannic acid, sodium alginate or sodium dodecyl sulfonate respectively as model foulants, ZPMs exhibited low water flux reduction and high water flux recovery after cleaning due to increased hydrophilicity and surface smoothness. Therefore, the ZPMs with improved separation and antifouling performances are promising candidates for practical application in brackish water desalination.

Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

Various membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD), osmotic distillation (OD) and osmotic membrane distillation (OMD) use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED), membrane capacitive deionization (MCD), reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), microfiltration (MF), etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling), fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application.

Identification of the type of foulants and investigation of the membrane cleaning methods for PRO processes in osmotic power application

Pressure retarded osmosis (PRO) is a membrane based technology used for generation of osmotic power as a sustainable energy. The main challenge of PRO technology is the membrane fouling which reduces the permeate flux and osmotic power generation which consequently increases the cost. In this research, different quality feed waters were used to identify the main foulants on the surface of a commercial semi permeable membrane in the PRO process. In addition, two cleaning methods were investigated to determine the desirable cleaning methods. According to the results, the main inorganic foulants using synthetic salt water were iron, aluminum, calcium, sodium, and silica and when sea water was used as the draw solution, the same foulants, in addition to magnesium and potassium were detected. The organic foulants were humic substances, polysaccharides and proteins for both synthetic salt and sea water draw solutions. According to the results, the water flux recoveries were 98.4%, 98%, 97.5%, 97.3%, and 97.2% after each sequential chemical cleaning, respectively. Therefore, the most successful cleaning method was with acidic and basic cleaners. This research indicates that chemical cleaning can decrease the membrane fouling in PRO processes and consequently improve the osmotic power generation.

Impact of the fouling mechanism on enzymatic depolymerization of xylan in different configurations of membrane reactors

In order to maximize enzymatic xylan depolymerization while simultaneously purifying the resulting monosaccharide (xylose), different ultrafiltration (UF) membrane reactor configurations were evaluated. Initial results showed that the two hydrolytic enzymes required for complete depolymerization of xylan, endo-1,4-β-xylanase and β-xylosidase, promoted different types of fouling, which had a direct impact on the extent of xylan hydrolysis achieved during reaction. Endo-1,4-β-xylanase generated DP 1–6 xylo-oligomers. These products contributed to partial pore blocking of the 1 kDa polysulfone membrane and caused irreversible flux loss (∼20%). The presence of β-xylosidase could not prevent deposition of xylan and xylooligomers on the UF membrane surface. Mulder’s modelling of the filtration parameters affirmed that this xylan and xylooligosaccharide deposition formed a cake layer on the membrane which hindered enzymatic attack in addition to fouling. Reaction with both enzymes followed by UF was found to be the optimal configuration, providing at least 40% higher xylan hydrolysis than the cascade configuration (involving sequential reaction with each of the enzymes separately) and the simultaneous reaction-filtration with both enzymes, respectively. This study thus confirmed that the reactor configuration has a crucial impact on the performance of both the reaction and the separation process of xylose during enzymatic xylan degradation, and that the type of fouling mechanism varies in response to the type of enzyme treatment.

A comparison study: The different impacts of sodium hypochlorite on PVDF and PSF ultrafiltration (UF) membranes

Chemical ageing of ultrafiltration membranes related to drinking water operation is not a new problem, but literature documenting sieving properties and fouling behaviors of aged membranes are scarce. This paper shows how the surface chemistry evolution of polysulfone (PSF) and polyvinylidene fluoride (PVDF) membranes can lead to the formation of distinct membrane properties when exposed to sodium hypochlorite solutions. The surface physicochemical evolutions of aged membranes are characterized based on chemical composition (ATR-FTIR and XPS), water contact angle analysis, and surface zeta potential test. The results indicate the ageing mechanism and evolutions between PSF and PVDF membranes are totally different. In addition, the retention ability and fouling propensity of the aged membrane are also investigated by three different kinds of foulant (Dextran/HA/BSA). Surface hydrophilization of aged PVDF membrane enhanced its retention toward neutral (Dextran) and hydrophilic charged foulant (BSA), but the fouling type of aged PVDF membranes remained the same, in spite of the initial flux increasing greatly. In terms of PSF membranes, pore enlargement could be verified by a seemingly inconsistent result of dextran sieving experiments and the decreased HA rejection rate. Moreover, the increased negative charge on aged PSF membrane surface have a great impact on its sieving property and fouling propensity, especially for the charged and hydrophilic BSA. With the regression data of Hermia's model, the main fouling type of aged PSF membranes was proven changed to pore blocking, and the changes can ascribe to its altered surface chemical characteristic and pore diameter.

Polymeric membranes for produced water treatment: an overview of fouling behavior and its control

Abstract Produced water (PW) from the oil/gas field is an important waste stream. Due to its highly pollutant nature and large volume of generation, the management of PW is a significant challenge for the petrochemical industry. The treatment of PW can improve the economic viability of oil and gas exploration, and the treated water can provide a new source of water in the water-scarce region for some beneficial uses. The reverse osmosis (RO) and selective nanofiltration (NF) membrane treatment of PW can reduce the salt and organic contents to acceptable levels for some beneficial uses, such as irrigation, and different industrial reuses. However, membrane fouling is a major obstacle for the membrane-based treatment of PW. In this review, the author discusses the polymeric membrane (mainly RO/NF) fouling during PW treatment. Membrane fouling mechanisms by various types of foulants, such as organic, inorganic, colloidal, and biological matters, are discussed. The review concludes with some of the measures to control fouling by membrane surface modification approaches.