Application Of Membrane Technology Research Articles

Role of body fluid on the removal of haloacetic acids from swimming pool water by nanofiltration

Considering the co-presence of body fluids and haloacetic acids (HAAs) in swimming pool waters (SPWs), as well as the potential for interaction among these substances and membranes, we have conducted a systematic investigation into the impact of body fluid analogue (BFA) on membrane performance. The minor impact of BFA on the rejection behavior of NF90 was attributed to its dominant effect of size exclusion. However, for NF270, 30 mg/L BFA increased water flux by 5%, decreased NaCl rejection from 59% to 47%, and decreased HAA rejection from 88% to 75%. The carboxyl-based components in BFA, including citric acid (CA) and hippuric acid (HA), were mainly responsible for the varied performance. Carboxyl-based components reduced the negative charge on membrane surfaces, increased the effective pore size and hydrophilicity, resulting in an increase for water flux and a decrease for NaCl and HAA rejection. The amine-based components (other BFA components with CA, HA, and salt excluded) did not directly influence the membrane performance, but their effect became remarkable under the coexistence of carboxyl-based components. The amine-based components neutralized the effect of the carboxyl-based components by forming hydrogen bonds. The practical application of membrane technology for water purification can be better predicted by the underlying mechanism for resolving the interaction among polyamide membranes, organic substances, and trace contaminants.

Role of competitive effect in the separation mechanism of matrine and oxymatrine using commercial NF membranes

Sophora flavescens contains two alkaloids, matrine (MT) and oxymatrine (OMT), which have similar structures but distinct functions and require separation. The present study employed four nanofiltration membranes, namely NT101, NT103, NF270, and NF90, in order to explore the rejection mechanisms of MT and OMT. The behavior of single-component and binary mixtures was assessed during nanofiltration at different pH values. To systematically compare the intermolecular interactions between different alkaloids and the membranes, molecular dynamics simulations (MDS) were conducted. The results indicated that rejection by NT101 and NF270 was primarily influenced by electrostatic and hydrophobic effects. Owing to their relatively smaller pore size, rejections for NF90 and NT103 remained consistently high under the sieving effect. In addition, binary aqueous solutions consisting of MT and OMT can be separated by NT101 (separation factor of 5.46 after secondary filtration), probably because alkaloids compete for adsorption on the membrane. MDS demonstrated that the presence of MT increased the distance and weakened the interaction between OMT and the membrane, increasing OMT rejection. This study provides insightful guidance for the effective application of membrane technology in the separation of natural products.

Ceramic membrane with double catalytic layer for efficient peroxymonosulfate activation and dissolved organic matter (DOM) membrane fouling control

Membrane fouling and low removal of dissolved organic matter (DOM) are the main obstacles for the wide application of ultrafiltration membrane technology in water treatment. Herein, we reported the preparation and application of a novel ceramic membrane, which embedded the cobalt oxide in the membrane support layer, and simultaneously loaded the CoAl composite bimetallic oxide on membrane surface layer. The double catalytic layer membrane (CoAl@AM-Co) enabled more efficient DOM removal and membrane fouling mitigation via in situ peroxymonosulfate (PMS) activation during filtration of actual raw water. Compared to the ceramic membrane with only single catalytic layer, the CoAl@AM-Co/PMS system could achieve much higher normalized membrane flux (0.79 vs. 0.63 and 0.49) and TOC removal (87.47 % vs. 58.35 % and 47.16 %); meanwhile, the molecular weight of DOM in the permeate water would also be significantly decreased. The FT-ICR MS results indicated that the total amount of DOM molecules of the permeate was reduced; the DOM with high H/Cwa and low O/Cwa value could be more easily removed, accompanied with the production of DOM with higher oxidation and unsaturation degree. Singlet oxygen and surface-bound radicals were proved to play a critical role in mitigating the membrane fouling by DOM. The design of ceramic membrane equipped with double catalytic layer and its application in advanced water purification were systematically elucidated for the first time in this work, which provided a new pathway for efficient treatment of surface water containing DOM.

Effects of nanofiltration on desalination of flue gas desulfurization wastewater by electrodialysis: Treatment effect, fouling property and techno-economic analysis

This study seeks to compare the treatment effect and fouling property of the nanofiltration (NF) – electrodialysis (ED) hybrid system and single ED system, and launches a techno-economic analysis for the flue gas desulfurization wastewater treatment. The optimal operation conditions of ED and NF process were determined, and the fouling properties of NF membranes and ion exchange membranes (IEMs) were explored. Morphology and chemical structure analysis concluded that NF membranes are more susceptible to fouling than IEMs, ascribing to the discrepancy of driving force and fouling mechanisms. The economic impact of membrane fouling was calculated in detail, including costs of increased membrane resistance and pressure drop of feed channel, decreased water permeability, membrane replacement and cleaning-in-place (CIP). We have found that the major factor of increased operating cost resulting from fouling comes from the membrane replacement cost (≥66%), followed by additional energy cost (≥4.1%) and with only a minor contribution from the CIP costs (≥0.8%). Overall, the total operating cost for the NF-ED system was 35.9% more expensive than the single ED system with a total cost of 2.95 ¥/m3. The results can provide a useful reference for the application of membrane technology in water and wastewater treatment.

Application of nonwoven microfiltration membrane on activated sludge final effluent: improving wastewater quality for reuse

The application of membrane technology in wastewater treatment for reuse is one of the alternatives to reduce the demand of water in domestic, agricultural and industrial sectors. This study attempts to improve wastewater quality effluent, prior to disinfection, for re-use. Clarifier effluent from a biological nutrient removal (BNR) treatment plant was diverted to a nonwoven membrane pilot filtration unit. It was thus positioned to further enhance the clarifier effluent as a polishing arrangement. Water Quality Index (WQI), Single Factor Pollution Index (Pi), Water Use License (WUL) and removal efficiency methods were used to interpret the water quality data for BNR clarifier effluent and nonwoven membrane permeate. The results showed that this nonwoven microfilter membrane is able to improve wastewater quality from BNR clarifier effluent. Escherichia coli (E. coli) reduction was the highest with a removal efficiency of 90%, followed by chemical oxygen demand 25%, NH4+ 22%, NO3− 12.6%, PO4 7.8%, suspended solids 6.3%. The lowest reduction was electrical conductivity of 5.2%. Permeate results indicated that physiochemical and microbial parameters were complying with the limits of WUL. Pi has revealed that BNR clarifier effluent water quality is medium polluted versus slightly polluted permeate. WQI results for BNR clarifier effluent showed good water quality and the water can be reused for domestic, irrigation and industrial purposes, while permeate WQI results indicated excellent water quality and the water can be reused for drinking, domestic, irrigation and industrial purposes. Outstanding permeate water quality improvement was observed on E.coli counts improving from 4974.48 to 294.33 counts/L. The standard of E.coli according to the WUL at this wastewater care works is 500 counts/L. Results indicate that nonwoven membrane filtration can improve microbial contamination and decrease the demand of chlorine for disinfection of wastewater final effluent. The nonwoven membrane filtration can decrease the water scarcity gap in South Africa for direct water reclamation by improving effluent wastewater.

Progresses of advanced anti-fouling membrane and membrane processes for high salinity wastewater treatment

Membrane fouling during the high salinity wastewater treatment is a critical bottleneck restricting the sustainable application of membrane technologies. Developing advanced anti-fouling membranes and membrane processes is necessary, promising to solve the problem fundamentally and economically. Herein, this review focuses on nanofiltration (NF), reverse osmosis (RO) and membrane distillation (MD) applied for the high salinity wastewater treatment, and contrastively reviews membrane fouling processes and developing strategies of anti-fouling membranes and membrane processes. Types of foulants and membrane fouling mechanisms in different membrane processes are discussed, involving the most recent anti-fouling theory, and the difference caused by the separation mechanism, membrane property and operating condition is emphasized. Based on this understanding, to the material, the design and preparation of advanced anti-fouling membranes in NF, RO and MD process for different membrane foulants are reviewed. Then to the process intensification, the applications of external assistances such as the bubbling, ultrasonic, electric field and magnetic field for enhancing anti-fouling performance are also presented. Finally, the research status and existing problems in developing sustainable membrane processes are summarized, and future research needs are prospected. This review is expected to provide a valuable reference in the development of advanced membrane processes with improved sustainability for treating the high salinity wastewater.

Performance of a ceramsite-enhanced gravity-driven ceramic membrane (GDCM) for simultaneous manganese ion and ammonia removal

Rapid population and economic growth have led to increased discharge of industrial wastewater into the aquatic environment. Multiple contaminants, such as ammonia and manganese ion in groundwater, may pose a significant risk to our drinking water safety. In this work, a novel groundwater purification system (i.e., a ceramsite-dosed gravity-driven ceramic membrane (GDCM)) has been applied to simultaneously remove manganese ion and ammonia for 60 days. The GDCM showed excellent ammonia and manganese ion removal; this performance was attributed to the degradation by enriched bacteria (5.2×106 CFU/mL), along with highly catalytic birnessite that enhanced both biotic and abiotic oxidation of ammonia and manganese ion. The proportions of heterotrophic nitrifying and aerobic denitrifying bacteria (HN-AD) and manganese oxidizing bacteria (MnOB) (Hyphomicrobium) existing in the GDCM were 81.51% and 0.24%, respectively. Besides, the mixture/separate/deposit of PAC-MnOx (powdered activated carbon) and ceramsite provided favorable ecological conditions for the efficient removals of manganese ion (<0.1 mg/L) and ammonia (not detected) in the later stage. The flux of mixture-mode and separation-mode were stabilized at 13.9 LMH and 10.9 LMH, respectively, owing to the decreased porosity of fouling layer after the long-term operation, as confirmed by the BET analysis. Additionally, divalent manganese ion still existed in the PAC-MnOx and the peak intensity of birnessite increased significantly over time, as demonstrated by SEM-EDS mapping, Raman analysis, X-ray diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) analysis. From the perspective of real application, inoculation of cycled raw water (GDCM 3#) and transfer of mature filter material (GDCM 4#) into a new GDCM tank significantly reduce the ripening time (Not even needed), while the purification effect of manganese ion and ammonia can also be satisfactory. It was particularly noted that the membrane fouling control effect of mixture-filled mode (GDCM 1-1#) was the most significant, that was, the minimum irreversible fouling was 4.8×108 m−1. At the same time, the ripen period of the mixture-filled mode was 5 days earlier than that of the separation-mode, and the final stable flux was slightly larger (17.25 LMH>16.25 LMH). In conclusion, the novel strategy, PAC-MnOx filled ceramsite composite GDCM system, was satisfactory in treating manganese ion and ammonia-containing groundwater as well as encouraging extensive applications of membrane technologies for drinking water supply.

Analysis of the limits in the application of membrane technologies in Polish water supply systems using the reverse osmosis process as an example

Analysis of the limits in the application of membrane technologies in Polish water supply systems using the reverse osmosis process as an example

Evaluation of an ultrafiltration membrane for the removal of fish viruses and bacteria in aquaculture water

Ultrafiltration (UF) membranes are used to successfully remove waterborne virus and bacteria from wastewater and drinking water. However, UF membrane application in aquaculture water treatment is limited. In this study we evaluate the performance of a capillary polyethersulfone UF membrane to remove two benchmark waterborne fish pathogens: i) the infectious pancreatic necrosis virus - IPNV, which is an unenveloped icosahedral virus, and ii) the bacterium Aeromonas salmonicida, which is a Gram-negative, facultative anaerobic bacilli. Moreover, the UF membrane bench-scale unit was tested at two temperatures according to salmonid aquaculture: low (4 - 7°C) and high (16 - 19°C). Sterilised natural seawater was spiked with laboratory cultured pathogens, the water was filtrated, and the membrane permeate collected. Both pathogen solution and permeate were evaluated using a cell culture method to estimate the colony-forming units (CFU/ml) for bacteria presence, a median tissue culture infectious dose (TCID50/ml) assay for virus presence, and real-time quantitative polymerase chain reaction (RT-qPCR) for both bacteria and virus presence. The membrane permeate was negative for both virus and bacteria for all analysis and for both low and high temperatures. The results from this bench-scale study are encouraging for the application of UF membrane technology in aquaculture water treatment to prevent virus and bacteria outbreaks. Further studies should validate this UF membrane technology results in commercial aquaculture conditions.

A review on membrane technology application for vegetable oil purification processes

AbstractIn current paper, a comprehensive review to contribute the present insight an implementations and the recent improvements through the diverse endeavor made by the researchers utilizing a membrane technique for degumming, deacidifying, dewaxing and discoloration edible vegetable oils with and without solvent availability and also the solvent recovery has been evaluated. Endeavors made with NF, UF, MF and non-porous membranes, have shown the capability of these membranes to predicate vegetable oil treatment. A membrane technique is noticeably simple and potentially provides many usefulness in vegetable oil purification. It appears that oils treatment with membranes, which carried out at low temperatures that provides saving energy, with real cancellation of stages, provides a promising alternate to conventional procedure, towards the accomplishment of eco-friendly and cost-effective operations that are technically sophisticated. Generally, the solvent (hexane-dilution) technique enhances the membrane oil flux. For dewaxing undiluted vegetable oils, the effective membrane was MF, whereas in dewaxing solvent-diluted oils process UF membranes were more energetic.

A method for increasing the efficiency of an internal combustion engine based on membrane technologies

The features of the application of membrane technologies for improving the operation of internal combustion engines by increasing efficiency are considered. A comparative analysis of existing and possible installations in the automotive industry has been carried out. A technological scheme and a mathematical model have been developed. The advantages and disadvantages of using membranes in internal combustion engines are given. Conclusions are drawn about the efficiency of using the installation, in order to increase power and fuel efficiency. Keywords: Membrane technology, air separation, oxygen enrichment of the fuel-air mixture, membrane apparatus, improvement of the internal combustion engine

Magnetic spent coffee biochar (Fe-BC) activated peroxymonosulfate system for humic acid removal from water and membrane fouling mitigation

Applying membrane technology to water purification has been done for several decades now and is widespread. However, membrane fouling is a serious problem and continues to limit the success of membrane processes. In this study, magnetic biochar (Fe-BC) was prepared using easily available spent coffee grounds to activate peroxymonosulfate (PMS) as a UF membrane pretreatment strategy. Results showed that the average removal rates of humic acid (HA, 10 mg/L) were 55.23 % and 73.55 %, at the Fe-BC dosage of 300 mg/L and PMS dosage of 300 mg/L and 900 mg/L, respectively. The Fe-BC/PMS pretreatment significantly reduced the total (44 %) and reversible (61 %) UF membrane fouling after five filtration cycles at a relatively high flux of 200 L/m2·h, and the Fe-BC and PMS dosage of 100 mg/L. Modeling fit results indicated that pretreatment shifted complete blocking to standard blocking. Therefore, stopping HA-induced membrane fouling could be possible if the load is reduced and complete blocking alleviated.

Study on pickling technology to control fouling of ceramic membrane treating secondary treated effluent.

The application of membrane technology in the field of water treatment was increasingly widespread, but membrane fouling still restricted its development, and the membrane needed to be chemically cleaned. This research focused on the high-efficiency pickling technology of ceramic membrane, and developed the cleaning technology of ceramic membrane in cooperation with surfactant. In the experiment, the municipal secondary effluent was used as the raw water, and the single-step, mixed and step-by-step cleaning effects of three strong acids, three weak acids and surfactants on ceramic membranes and polyvinylidene difluoride (PVDF) membranes were investigated. For ceramic membrane, the optimal cleaning combination was H2SO4 first and then DTAC, and the flux recovery rate could reach 96.94%; for PVDF membrane, the optimal cleaning combination was HNO3 first and then H2SO4, and the flux recovery rate could reach 93.72%. In addition, the surface of initial, polluted, and cleaned membranes were analyzed by scanning electron microscope and contact angle, and the fouling mechanism of the ceramic membrane was analyzed. The results showed that through physical cleaning and chemical cleaning, most of the pollutants on the membrane surface and pores were removed. The cleaning method can effectively control the membrane pollution.

Review of Hollow Fiber (HF) Membrane Filtration Technology for the Treatment of Oily Wastewater: Applications and Challenges

Oily wastewater has been recognized as a threat to the environment due to its hazardous nature and it can negatively affect the ecosystem, and threaten wildlife and human health. Physical, chemical, and biological technologies demonstrated a mixed performance in oily wastewater treatment, and, therefore, a proper treatment technology for oily wastewater needs to be addressed. Membrane filtration using a hollow fiber (HF) membrane is a promising alternative to remove emulsified oil from oily wastewater. This review discusses different sources of oily wastewater, various treatment methods, and membrane technology. The assessment has been focused on the parameters affecting HF membrane performance and applications of HF membrane-based technology to treat oily wastewater. This review paper reveals that HF membrane filtration systems have been previously used for the treatment of oily wastewater in bench-scale studies and few pilot-scale applications, which proved to be favorable in the treatment of recalcitrant wastewater containing oil and high salinity. Limitations associated with membrane fouling and the reduction of membrane permeability and membrane lifespan can be tackled and alleviated through modifying membrane chemistry and adjusting operational parameters. The compilation of studies showed that a low food/microorganism (F/M) ratio, long solid retention time (SRT) with high sludge age, long hydraulic retention time (HRT), and moderate aeration were the preferred operational parameters when treating oily wastewater. Based on this review, future studies should focus on optimizing the hydrodynamic conditions of the HF system, the commercialization of modified HF membranes, and the utilization of green technology in HF membrane construction to broaden HF membrane technology applications.

Membranes for Oil/Water Separation: A Review.

Recent advancements in separation and membrane technologies have shown a great potential in removing oil from wastewaters effectively. In addition, the capabilities have improved to fabricate membranes with tunable properties in terms of their wettability, permeability, antifouling, and mechanical properties that govern the treatment of oily wastewaters. Herein, authors have critically reviewed the literature on membrane technology for oil/water separation with a specific focus on: 1) membrane properties and characterization, 2) development of various materials (e.g., organic, inorganic, and hybrid membranes, and innovative materials), 3) membranes design (e.g., mixed matrix nanocomposite and multilayers), and 4) membrane fabrication techniques and surface modification techniques. The current challenges and future research directions in materials and fabrication techniques for membrane technology applications in oil/water separation are also highlighted. Thus, this review provides helpful guidance toward finding more effective, practical, and scalable solutions to tackle environmental pollution by oils.

SVM and ANN Modelling Approach for the Optimization of Membrane Permeability of a Membrane Rotating Biological Contactor for Wastewater Treatment.

Membrane fouling significantly hinders the widespread application of membrane technology. In the current study, a support vector machine (SVM) and artificial neural networks (ANN) modelling approach was adopted to optimize the membrane permeability in a novel membrane rotating biological contactor (MRBC). The MRBC utilizes the disk rotation mechanism to generate a shear rate at the membrane surface to scour off the foulants. The effect of operational parameters (disk rotational speed, hydraulic retention time (HRT), and sludge retention time (SRT)) was studied on the membrane permeability. ANN and SVM are machine learning algorithms that aim to predict the model based on the trained data sets. The implementation and efficacy of machine learning and statistical approaches have been demonstrated through real-time experimental results. Feed-forward ANN with the back-propagation algorithm and SVN regression models for various kernel functions were trained to augment the membrane permeability. An overall comparison of predictive models for the test data sets reveals the model’s significance. ANN modelling with 13 hidden layers gives the highest R2 value of >0.99, and the SVM model with the Bayesian optimizer approach results in R2 values higher than 0.99. The MRBC is a promising substitute for traditional suspended growth processes, which aligns with the stipulations of ecological evolution and environmentally friendly treatment.

Alternative fouling analysis of PVDF UF membrane for surface water treatment: The credibility of silver nanoparticles

The prevalence drawback of membrane technology applications is rapid flux declines due to fouling. Membrane fouling analysis is vital to explicitly understand fouling occurrences. Alternatively, silver nanoparticles (AgNPs) incorporated in PVDF membranes are utilized for Raman spectroscopy (SERS) as an unconventional approach of built-in surface that enhances substrate. The thermogravimetric analysis (TGA) has been employed to quantify foulant as an approach to evaluate the performance of AgNPs for fouling mitigation during surface water filtration. In this study, two types of AgNPs, namely AgNPs-1 and AgNPs-2, were respectively incorporated in the PVDF ultrafiltration (UF) membrane. The scanning electron microscopy (SEM), flux decay rate (FDR), and flux recovery ratio (FRR) analyses of clean and fouled membranes have implied membrane fouling phenomena. Small significant peaks representing biofoulant presence were obtained from normal Raman while total foulant weight indicated reductions of 82.69% and 75.86% with the presence of AgNPs-1 and AgNPs-2, respectively. Hence, the unconventional approach in fouling analysis for AgNPs in PVDF membrane has potentially been earmarked for surface enhancement in normal Raman analysis while foulant quantification provided a profound understanding of fouling occurrences on the membrane which contribute to the development of the fouling mitigation approach.

Performance design of a highly anti-fouling porous membrane with dual pH-responsiveness

With the increasingly extensive application of membrane technology, facing the wastewater system with complex components, it is urgent to develop a porous membrane with excellent pollution-resistant and easily cleaned after pollution. Herein, a membrane with dual pH-responsiveness effects was successfully fabricated via a facile and eco-friendly method. The isoelectric point of zeta potential of the modified membrane (M-D-IA) appeared at pH = 4.31. It exhibited positive-charged and the water intake rate reached 427% under strongly acidic conditions, while it showed negative-charged with the water intake rate reaching 492% under strongly alkaline conditions, showing an excellent dual pH-responsiveness. Meanwhile, the membrane M-D-IA possessed good super-hydrophilic and underwater super-oleophobic surface characteristics. Furthermore, the membrane M-D-IA displayed an excellent oil-fouling resistance in the treatment of hexadecane/water mixed emulsion, with the water flux decay rate (FDR) only 17.5% after 7 cycles of operation and the water flux recovery rate (FRR) remained above 99.7% after alkali cleaning. Notably, the membrane M-D-IA also had excellent dual pH-responsiveness when treating typical polluted wastewater HA/CaCO3 feed solution. The FRR was as high as 98.3% after washing with alkali and acid solution in turn, indicating that the membrane not only possessed a significant resistance to organic/inorganic pollution but also had an outstanding recovery of membrane flux after cleaning. Moreover, the water flux of the membrane M-D-IA was maintained at 850 L m−2 h−1 during 30 days of storage, displaying an excellent resistance to biological pollution.

Anti-Pectin Fouling Performance of Dopamine and (3-Aminopropy) Triethoxysilane-Coated PVDF Ultrafiltration Membrane.

Due to the diversity and complexity of the components in traditional Chinese medicine (TCM) extracts, serious membrane fouling has become an obstacle that limits the application of membrane technology in TCM. Pectin, a heteropolysaccharide widely existing in plant cells, is the main membrane-fouling substance in TCM extracts. In this study, a hydrophilic hybrid coating was constructed on the surface of a polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane co-deposited with polydopamine (pDA) and (3-Aminopropy) triethoxysilane (KH550) for pectin antifouling. Characterization analysis showed that hydrophilic coating containing hydrophilic groups (–NH3, Si-OH, Si-O-Si) formed on the surface of the modified membrane. Membrane filtration experiments showed that, compared with a matched group (FRR: 28.66%, Rr: 26.87%), both the flux recovery rate (FRR) and reversible pollution rate (Rr) of the pDA and KH550 coated membrane (FRR: 48.07%, Rr: 44.46%) increased, indicating that pectin absorbed on the surface of membranes was more easily removed. Based on the extended Derjaguin–Laudau–Verwey–Overbeek (XDLVO) theory, the fouling mechanism of a PVDF UF membrane caused by pectin was analyzed. It was found that, compared with the pristine membrane (144.21 kT), there was a stronger repulsive energy barrier (3572.58 kT) to confront the mutual adsorption between the coated membrane and pectin molecule. The total interface between the modified membrane and the pectin molecule was significantly greater than the pristine membrane. Therefore, as the repulsion between them was enhanced, pectin molecules were not easily adsorbed on the surface of the coated membrane.

Effect of operation mode on membrane fouling from traditional Chinese medicine water extracts

Membrane technology is a viable alternative to many conventional methods currently used to process traditional Chinese medicine (TCM). However, membrane fouling is a significant obstacle to the application of membrane technology in TCM. In this study, the ultrafiltration (UF) membrane fouling from TCM water extracts under constant transmembrane pressure (TMP) and constant flux operation was studied in connection with critical and threshold flux determinations. Meanwhile, the physicochemical foulant–membrane interactions were analyzed using the extended Derjaguin, Landau, Verwey, and Overbeek (XDLVO) theory. At constant TMP operation, the high pressure resulted in a rapid drop in permeate flux at the start of the filtration period, but the steady-state fluxes did not increase significantly with an increase in TMP. At constant flux operation, the TMP increased somewhat when the permeate flux was below the threshold flux. Fouling was severe above the threshold flux, and the TMP rapidly increased. By displaying fouling resistance as a function of permeate volume, the constant flux operation was compared to a constant TMP operation beginning at the same flux imposed during the constant flux operation. Below the threshold flux, fouling resistance was similar for constant TMP and constant flux operations. However, above the threshold flux, fouling resistance under constant flux operation was much greater than fouling resistance under constant TMP operation. The results of physicochemical interactions showed that there are attractive interactions between hydrophobic membrane and foulants in the TCM water extracts. These interactions should be considered a key factor leading to serious membrane fouling.