Filtration Of Solutes Research Articles

The porosity and morphology properties of ceramic membrane

The success of ceramic membranes as solute separation and filtration makes membrane technology widely used because it has high effectiveness and efficiency as a solute separator and filtration. The solute separation and filtration performances of typical ceramic membranes depend on the porosity properties of the ceramic membrane itself. Membrane porosity indicates the number of porous areas in the membrane. Precipitated silica as filler was added into the ceramic membrane at 0.30 %, 1.01 %, 1.68 %, 2.34 %, and 2.99 % per hundred masses of the membrane. It was revealed that silica acting as a membrane filler increased the porosity of the ceramic membrane. This was confirmed with the SEM (Scanning Electron Microscopy) test and Origin Software. From the test results the highest porosity value is at 2.99 % per hundred masses of membrane.

Sodium, Interstitium, Lymphatics and Hypertension-A Tale of Hydraulics.

Blood pressure is regulated by vascular resistance and intravascular volume. However, exchanges of electrolytes and water between intra and extracellular spaces and filtration of fluid and solutes in the capillary beds blur the separation between intravascular, interstitial and intracellular compartments. Contemporary paradigms of microvascular exchange posit filtration of fluids and solutes along the whole capillary bed and a prominent role of lymphatic vessels, rather than its venous end, for their reabsorption. In the last decade, these concepts have stimulated greater interest in and better understanding of the lymphatic system as one of the master regulators of interstitial volume homeostasis. Here, we describe the anatomy and function of the lymphatic system and focus on its plasticity in relation to the accumulation of interstitial sodium in hypertension. The pathophysiological relevance of the lymphatic system is exemplified in the kidneys, which are crucially involved in the control of blood pressure, but also hypertension-mediated cardiac damage. Preclinical modulation of the lymphatic reserve for tissue drainage has demonstrated promise, but has also generated conflicting results. A better understanding of the hydraulic element of hypertension and the role of lymphatics in maintaining fluid balance can open new approaches to prevent and treat hypertension and its consequences, such as heart failure.

Influence of utilizing hemodialysis membranes outside-in on solute clearance and filtration efficiency – One step towards a novel combined lung and kidney support device

Many membrane oxygenator patients suffer from renal disfunction. For these patients, a novel device integrating artificial lung and kidney support is being developed. Although outside-in blood flow is standard for membrane oxygenators, this is not typical for hemodialysis systems. The effect of outside-in blood flow on the efficiency of hemodialysis fibers for continuous hemodialysis and hemofiltration is yet unclear.This study evaluates the efficiency of commercial hemodialyzer membranes utilized outside-in compared to traditional inside-out mode regarding clearance of urea and creatinine, and ultrafiltration coefficient during in-vitro tests with porcine blood. Our results showed that dialyzers (1.2 m2, asymmetric hollow fibers) utilized outside-in had similar clearances of urea and creatinine compared to dialyzers used in the traditional mode (p > 0.7). However, outside-in dialyzers had an ultrafiltration coefficient four times lower than dialyzers applied in a conventional way, but adequate fluid removal could be achieved by controlling pressures in the system. This in-vitro study indicates that outside-in fibers could be sufficiently effective to maintain typical continuous renal replacement therapy doses. We regard this as one step towards a novel device with a mixed membrane fiber bundle utilizing blood flow outside both hemodialysis fibers and gas exchange fibers to provide simultaneous lung and kidney support.

Facile Synthesis of Electrically Conductive Membranes.

A facile and effective strategy that can be used to fabricate electrically conductive membranes (ECMs) of diverse filtration performance (i.e., water productivity and solute rejection) is not available yet. Herein, we report a facile method that enables the fabrication of ECMs of a broad performance range. The method is based on the use of polyethylenimine (PEI), glutaraldehyde, and any of a diverse set of conductive materials to cast an electrically conductive layer atop any of a diverse set of substrates (i.e., from microfiltration to reverse osmosis membranes). We developed the reported ECM fabrication method using graphite as the conductive material and PVDF membranes as substrates. We demonstrate that graphite-PVDF ECMs were stable and electrically conductive and could be successfully used for solute filtration and electrochemical degradation. We also confirmed that the PEI/glutaraldehyde-based ECM fabrication method is suitable for conductive materials other than graphite, including carbon nanotubes, reduced graphene oxide, activated charcoal, and silver nanoparticles. Compared with the substrates used for their fabrication, ECMs showed low electrical sheet resistances that varied with conductive material, increased solute rejection, and reduced water permeance. Taken together, this work presents a promising general strategy for the fabrication of ECMs for environmental applications from diverse substrates and conductive materials.

Preparation and surface modification of ultrahigh throughput tannic acid coblended polyethersulfone ultrafiltration membranes for hemodialysis

AbstractLow dialysis and blood incompatibility efficiency are key issues to be addressed for polymeric hemodialysis membranes. To improve the comprehensive performance of hemodialysis membranes, polyethersulfone (PES)/tannic acid (TA) coblended ultrafiltration membranes were prepared and modified with a heparin‐like functionalized TA coating. The coblended TA improved the pore structure of the PES ultrafiltration membrane. And it could also undergo π‐π conjugation with the heparin‐like functionalized TA in the modified solution, resulting in a greater abundance of modified groups loaded on the membrane surface and pores close to the surface. The modified coating further improved the membrane performance. The physicochemical properties, solute filtration, and blood compatibility properties of the membrane were tested. The effect of TA on the pore structure of the membrane and the presence of modified layers were demonstrated by morphological and chemical structure analyses. The final modified membrane had an ultrahigh water flux (1053 L/m2·h), improved dialysis performance (BSA retention >99%, Lysozyme clearance >30% and Urea clearance >90%), and excellent hemocompatibility (The hemolysis rate was 1.31%, and APTT, PT, and TT values were increased by 40.8%, 74.2%, and 85.9%, respectively). This study shows that TA has great potential for improving the pore structure of polymeric membranes.

IDENTIFICATION OF TRANSPORT PARAMETERS FOR THE SOLUTE FILTRATION THROUGH POROUS MEDIA WITH CLOGGING

The transport of highly concentrated solutions in porous media was studied both numerically and experimentally. For numerical modeling we used a mobile-immobile (MIM) approach that considers clogging phenomenon. The impurity transition between the mobile and immobile phases was defined by second-order Langmuir kinetics. Kozeny-Carman expression modeled the clogging. The model has four phenomenological parameters which cannot be measured directly. These parameters were identified by minimization of the cost function, which is the squared distance between experimental and numerical data. Dependencies of concentration and mass flux at the outlet were analyzed. Twenty-five different experiments were conducted, and it was shown that transport parameters do not depend on impurity concentration or pressure drop between the ends of the column.

Characteristics of modified polyvinyl alcohol/polyether sulfone membranes grafted silica from rice husk ash for ultrafiltration

Ultrafiltration membrane (UF) is a membrane capable of separating very small solutes, which are below 0.01 µm to 1 nm. UF membranes have been applied in the purification, concentration, filtration and separation of solutes in various industries such as the pharmaceutical, dairy, biotechnology and sewage treatment industries. But the main problem for UF membranes is fouling. To avoid this condition, preparing the modified polyvinyl alcohol/polyether sulfone grafted silica from rice husk ash (PVA/PES/SiO2) has been prepared by phase inversion induced with immersion precipitation method. The performance membranes were investigated by four kinds of modified PES/SiO2, PES/PVA3%/SiO2, PES/PVA5%/SiO2 and PES membrane as a comparison. The analysis of modified membranes performance was included permeation, physicochemical properties, permeation performance. The FT-IR spectra and XRD patterns confirmed that PVA/PES/SiO2 adsorbed to each other between PVA, PES and SiO2 and were not released during membrane formation. SEM analysis confirm that all the membrane showed the ultrafiltration structure.

Effect of Surface Modification with Electrospun Nanofibers on the Performance of an Ultrafiltration Membrane

Electrospinning of nanofibrous mats to create new membranes has been widely investigated, however surface modification of commercial membranes by electrospinning of nanofiber layer has received limited attention. In this work, the surface of a commercial polyethersulfone (PES) ultrafiltration membrane was coated with electrospun polyvinylidene fluoride (PVDF) hydrophobic nanofibers (NFs) for different time periods, i.e., 25 min, 125 min, and 250 min., and the effect of coating on the filtration performance was investigated. The membranes were characterized by scanning electron microscopy (SEM), contact angle measurement and further subjected to pure water permeation experiments, as well as the filtration of Ottawa River Water (ORW) and various protein solutes. By a thorough statistical analysis, it was concluded that the coating with the electrospun nanofiber layer enhanced the pure water permeation (PWP) flux. However, the fouling of the composite nanofiber/PES membranes was more severe due to the compaction of the soft nanofiber layer and the entrapment of foulants in the spaces between nanofibers. The nanofiber mat did not impact the separation of protein solutes as the composite and base PES membranes had the same protein removals.

Nanoscale Chemical Heterogeneity in Aromatic Polyamide Membranes for Reverse Osmosis Applications.

Reverse osmosis membranes are used within the oil and gas industry for seawater desalination on off-shore oilrigs. The membranes consist of three layers of material: a polyester backing layer, a polysulfone support and a polyamide (PA) thin film separating layer. It is generally thought that the PA layer controls ion selectivity within the membrane but little is understood about its structure or chemistry at the molecular scale. This active polyamide layer is synthesized by interfacial polymerization at an organic/aqueous interface between m-phenylenediamine and trimesoyl chloride, producing a highly cross-linked PA polymer. It has been speculated that the distribution of functional chemistry within this layer could play a role in solute filtration. The only technique potentially capable of probing the distribution of functional chemistry within the active PA layer with sufficient spatial and energy resolution is scanning transmission electron microscopy combined with electron energy-loss spectroscopy (STEM-EELS). Its use is a challenge because organic materials suffer beam-induced damage at relatively modest electron doses. Here we show that it is possible to use the N K-edge to map the active layer of a PA film using monochromated EELS spectrum imaging. The active PA layer is 12 nm thick, which supports previous neutron reflectivity data. Clear changes in the fine structure of the C K-edge across the PA films are measured and we use machine learning to assign fine structure at this edge. Using this method, we map highly heterogeneous intensity variations in functional chemistry attributed to N-C═C bonds within the PA. Similarities are found with previous molecular dynamics simulations of PA showing regions with a higher density of amide bonding as a result of the aggregation process at similar length scales. The chemical pathways that can be deduced may offer a clearer understanding of the transport mechanisms through the membrane.

Proximal Tubule Transport Function Screening Assay Used to Optimize Function of Kidney Organoids

BackgroundThe mechanisms that mediate solute filtration, reabsorption, secretion and excretion in the kidney are well established. However, there are a paucity of data regarding the functional properties of tubular epithelia cells within organoids. The goal of our current work is to define specific function properties of tubular epithelia cells within kidney organoids.Study objectivesTo develop quantitative assays adapted to human kidney organoids to measure proximal tubule function and test whether they can be used to optimize function in developing kidney organoids.MethodsOrganoids were generated from induced pluripotent stem cells (hiPS) derived from human fibroblasts. 6‐carboxyfluorescein (6CF) was used as a fluorescent prototype of organic anion transport (OAT), and was loaded into live organoids (1 mM in OptimemTM, with orbital rotation for 45 min), to measure basolateral uptake using confocal microscopy with tile scanning to test organoid populations and allow quantitation of transport function. To mimic continuous fluid shear stress which occurs in the PT, one population of organoids were placed on an orbital shaker (at 146 or 74 rpm for at least 30 hrs) prior to loading with 6CF. Organoids from the same culture batch at d 14 of differentiation were divided into two treatment groups, static and shaken, and loaded with 6CF, and imaged by a blinded investigator. Quantitation of average maximum intensity of basolateral uptake was done on organoid stacks using LASX software.ResultsOrganoids derived from the LRP2:mtagBFP2 reporter line (available through the Rebuilding a Kidney consortium) confirmed the PT segments within organoids and showed colocalization with 6CF. Concurrent treatment with probenecid (an OAT inhibitor) and 6CF inhibited uptake of 6CF into PT segments. Blinded quantitation of several organoid populations showed increased intensity of 6CF in PT segments subjected to chronic orbital shear. Assays demonstrated basolateral uptake and/or luminal secretion.ConclusionsKidney organoids subject to continuous fluid shear stress have increased basolateral anion transport capacity relative to static cultured controls. A screening assay for PT basolateral uptake, assumed to be OAT mediated, can be used to test and optimize PT function within developing human kidney organoids.Support or Funding InformationSupport from NIDDK: U01 DK107350RBK, 2 P30 DK079307‐07, R01 DK18726‐01.

Multipoint dilution hemofiltration: A new technology for maximum convective clearance.

Convection-based renal replacement therapies (RRTs) have the potential to improve patient outcomes when compared to diffusion-based RRT such as hemodialysis (HD), but have limited clearance rates. We propose and characterize multipoint dilution hemofiltration (MPD-HF), a purely convective blood purification technology which removes the fundamental filtration limit associated with convective RRT resulting in clearance rates on par with HD. In MPD-HF, filtration of liquid and solutes occurs along the length of the hollow fibers that convey the blood, and substitution fluid is pushed into the fibers at multiple points along their length. Since multiple filtration and dilution steps are contained within one pass of the blood through the hollow fiber, the fraction of fluid that can be filtered may be increased to allow a high clearance rate that removes a wide range of toxins. In vitro tests yielded an average steady-state filtrate fraction of 68%, exceeding commercial HDF cartridge filtrate fractions by a factor of approximately 3. The molecular weights of molecules cleared spans up to the cutoff of 66 kDa for albumin.

Filtration of Uncharged Solutes: An Assessment of Steric Effect by Transport and Adsorption Modelling

The major aim of this work was to understand and estimate the evolution of the membrane selectivity of neutral solutes after the filtration of protein or amino acid solutions. Classical methodologies led to the estimation of the mean pore radius, different for each filtrated neutral solute. The use of pore size distribution from nitrogen adsorption/desorption experiments enabled a good description of hydraulic and selectivity performances. The modification of the membrane hydraulic properties after the successive filtration of protein solutions revealed that the decrease is quasi linear, the same for all the studied membranes and independent of prior tests. According to the experimental observations, an adsorption model was developed, considering a layer by layer adsorption in the larger pores of the membrane. The predictive obtained results are in good agreement with the experimental rejection rates, validating the assumptions.

Glomerular Endothelium and its Impact on Glomerular Filtration Barrier in Diabetes: Are the Gaps Still Illusive?

Glomerular capillaries are lined with highly specialized fenestrated endothelium which are primarily responsible to regulate high flux filtration of fluid and small solutes. During filtration, plasma passes through the fenestrated endothelium and basement membrane before it reaches the slit diaphragm, a specialized type of intercellular junction that connects neighbouring podocytes. A PubMed search was done for recent articles on components of the glomerular filtration barrier such as glomerular endothelial cells, podocytes and glomerular basement membrane, and the effect of diabetes on these structures. Generally, the onset of kidney dysfunction in many diabetic patients is characterized by albuminuria/proteinuria, a pathophysiological event triggered by several factors including; (i) endothelial activation and shading of glycocalyx, (ii) loss of endothelial cell function, (ii) re-uptake of albumin by podocyte through a scavenger receptors and (iv) rearrangement of podocyte cytoskeleton. Howeover, as podocyte effacement does not always lead to proteinuria, the dynamic interplay between all constituents of the glomerular filtration barrier including podocytes, endothelial cells and the basement membrane may be fundamental for the effective filtration in healthy individuals. Thus, a putative cross-talk amongst podocytes, endothelial cells and the basement membrane in the homeostasis of glomerular function is envisaged. Although, the exact nature of this cross-talk remains to be clearly elucidated, it is possible that the interaction between: (i) glomerular endothelial cells and podocytes, (ii) glomerular endothelial cells and glomerular basement membrane, (iii) podocytes and glomerular basement membrane, and (iv) the simultaneous interaction amongst the three components collectively underpin effective filtration in healthy individuals. A comprehensive understanding of these different interactions still remains elusive. The elucidation of these multifaceted interactions will set the stage for greater understanding of the pathophysiology of kidney dysfunction.

Aqueous Solubility Enhancement for Bioassays of Insoluble Inhibitors and QSPR Analysis: A TNF-α Study

The aim of this study is to improve the aqueous solubility of a group of compounds without interfering with their bioassay as well as to create a relevant prediction model. A series of 55 potential small-molecule inhibitors of tumor necrosis factor–alpha (TNF-α; SPD304 and 54 analogues), many of which cannot be bioassayed because of their poor solubility, was used for this purpose. The solubility of many of the compounds was sufficiently improved to allow measurement of their respective dissociation constants (Kd). Parameters such as dissolution time, initial state of the solute (solid/liquid), co-solvent addition (DMSO and PEG3350), and sample filtration were evaluated. Except for filtration, the remaining parameters affected aqueous solubility, and a solubilization protocol was established according to these. The aqueous solubility of the 55 compounds in 5% DMSO was measured with this protocol, and a predictive quantitative structure property relationship model was developed and fully validated based on these data. This classification model separates the insoluble from the soluble compounds and predicts the solubility of potential small-molecule inhibitors of TNF-α in aqueous solution (containing 5% DMSO as co-solvent) with an accuracy of 81.2%. The domain of applicability of the model indicates the type of compounds for which estimation of aqueous solubility can be confidently predicted.

Negligible ageing in poly(ether-ether-ketone) membranes widens application range for solvent processing

Organic solvent nanofiltration membranes have been prepared from poly(ether-ether-ketone) (PEEK) by phase inversion. Remarkably, these membranes undergo negligible ageing, even under extreme conditions of high temperature air annealing, and high temperature solute filtration with aggressive solvents. This negligible ageing of PEEK membranes is contrasted with substantial ageing of crosslinked polybenzimidazole (PBI) and polyimide (PI) membranes. After air annealing at 120°C, PBI and PI membranes become brittle and lose all permeance, whereas PEEK membranes remain flexible and retain a constant permeance of ~0.2Lh−1m−2bar−1 for tetrahydrofuran (THF). The structural change in PBI and PI membranes is attributed to polymer transition from a non-equilibrium glassy state towards an equilibrium state at which chain packing precludes permeation of solvent. High temperature filtrations in DMF up to 140°C for the three polymeric membranes showed PEEK performance to be stable and consistent with negligible ageing, whereas PBI and PI rapidly loose stability.

Interfacial polymerization of cyanuric chloride and monomeric amines: pH resistant thin film composite polyamine nanofiltration membranes

Polyamine nanofiltration membranes have a high stability at extreme pH conditions. In contrast to polyamides, polyamines do not contain the carbonyl group that is susceptible to nucleophilic attack. A previous study has shown that polyamine membranes can be prepared from the interfacial polymerization reaction of polyethylenimine and cyanuric chloride, and that indeed these membranes have a high resistance towards hydrolysis. In the present study, the potential of a variety of other multifunctional amine / cyanuric chloride combinations is screened for the formation of stable polyamine nanofiltration membranes. For several traditional amine precursors it is found that the moderate reactivity of the cyanuric chloride hampers the formation of thin selective membrane films. For two linear amine monomers, both of which are precursors to polyethylenimine, the formation of well-defined, thin, stable, and selective polyamine films is observed. In particular, diethylene triamine is identified as a suitable monomer for the interfacial reaction. The membranes derived from this amine have a higher salt rejection and water permeability as compared to the previously studied polyethylenimine based membranes, and show a comparably high stability at extreme pH conditions. Cross-flow filtration of different salts and neutral solutes at different pH indicates that both steric effects as well as Donnan exclusion effects are relevant for the rejection of solutes. The membrane skin layer is very dense at neutral pH (MWCO of about 200Da), and becomes slightly more open at extreme alkaline conditions.

Preparation of Chemically-Tailored Copolymer Membranes with Tunable Ion Transport Properties.

Membranes derived from copolymer materials are a promising platform due to their straightforward fabrication and small yet tunable pore structures. However, most current applications of these membranes are limited to the size-selective filtration of solutes. In this study, to advance the utility of copolymer membranes beyond size-selective filtrations, a poly(acrylonitrile-r-oligo(ethylene glycol) methyl ether methacrylate-r-glycidyl methacrylate) (P(AN-r-OEGMA-r-GMA)) copolymer is used to fabricate membranes that can be chemically modified via straightforward schemes. The P(AN-r-OEGMA-r-GMA) copolymer is cast into asymmetric membranes using a nonsolvent induced phase separation technique. Then, the surface charge of the membrane is modified to tailor its performance for nanofiltration applications. The oxirane groups of the glycidyl methacrylate (GMA) moiety that line the pore walls of the membrane allows for both positively charged and negatively charged moieties to be introduced directly without any prior activation. Notably, the highly size-selective nanostructure of the copolymer materials is retained throughout the functionalization processes. Specifically, amine moieties are attached to the pore walls using the aminolysis of the oxirane groups. The resulting amine-functionalized membrane is positively charged and rejects up to 87% of the salt dissolved in a 10 mM magnesium chloride feed solution. Further modification of the amine-functionalized membrane with 4-sulfophenyl isothiocyanate results in pore walls lined by sulfonic acid moieties. These negatively charged membranes reject up to 90% of a 10 mM sodium sulfate feed solution. Throughout the modification scheme, the membrane permeability remains equal to 1.5 L m(-2) h(-1) bar(-1) and the rejection of neutral solutes (i.e., sucrose and poly(ethylene oxide)) is consistent with the membrane having a single well-defined pore diameter of ∼5 nm. The performance of the membrane as a function of ion valence number, solution pH, and ionic strength is investigated.

Mathematical Modeling of Different Molecule Removal on On-Line Haemodiafiltration: Influence of Dialysis Duration and Infusion Flow

Background: In a previous study on a nocturnal, every-other-day online haemodiafiltration scheme, different removal patterns were observed for urea, creatinine, β₂-​microglobulin, myoglobin and prolactin. The aim of this study was to evaluate the influence of dialysis duration and infusion flow (Qi) on the removal of different molecular weight (MW) solutes, and to quantify the effect of the different treatments on the kinetics of the solutes by using a classical two-compartment model. Methods: This prospective, in-center study was carried out in 10 patients on a nocturnal, every-other-day online post-dilution haemodiafiltration program. Each patient received four dialysis sessions with different conditions, two 4-h sessions (with infusion flows of 50 or 100 ml/min) and two 8-h sessions (with infusion flows of 50 or 100 ml/min). To analyze the solute kinetics, blood samples were obtained hourly during the dialysis treatments and in the first 3 h post-dialysis. Results: Removal patterns differed in the molecules studied, which were quantified by means of the two-compartment mathematical model. The main results show the impact of dialysis duration on the removal of low molecular weight molecules (urea and creatinine), while the impact of Qi is clearly shown for high molecular weight molecules (myoglobin and prolactin). For middle molecular weight solutes, such as β₂-microglobulin, both factors (duration and Qi) enhance the removal efficiency of the dialyzer. Conclusions: Our study evaluates experimentally and mathematically how treatment time and infusion flow affect the filtration of solutes of different MW during post-dilution haemodiafiltration. The results provided by the present study should help physicians to select and individualise the most appropriate schedules to deliver an optimum diffusive and convective dialysis dose for each patient.

Dual-porosity model of mass transport in electroporated biological tissue: Simulations and experimental work for model validation

Abstract Electroporation or pulsed electric field treatment is an important technique for facilitating mass transport in biological tissues with proven benefits for the food processing industry. One of the challenges in understanding its basic mechanisms and effects is mass transport processes in treated tissue. We recently presented a mathematical model called dual-porosity model to describe post-electroporation diffusion in biological tissue and filtration–consolidation behavior of electroporated tissue during pressing. In this work we bring the two analogues together and study the model's applicability and performance by comparing experimental and simulated kinetics. We use two kinds of plant tissue of dissimilar properties (sugar beet taproot and apple fruit), but employ the same methodology to evaluate the validity of basic assumptions. We show that the model describes experimental data and provides more insight into the mass transport processes during post-pulse extraction/pressing. We comment on treatment conditions that expose limitations and indicate possibilities for future development. Industrial relevance In order to study and optimize extraction processes following treatment of biological material with electroporation (pulsed electric fields), good knowledge on mass transport processes in electroporated tissue is of essential importance. Development, final form and application of a new mathematical model are presented that will aid in understanding of mass transport by solute diffusion and filtration–consolidation behavior of electroporated tissue under external pressure. It is foreseen that such a model could be used for predictive purposes and optimization of treatment parameters in industrial applications of electroporation, where in silico modeling can thus help find new or improved protocols to increase efficiency and efficacy in pulsed electric field applications.

Comparison study on membrane fouling by various sludge fractions with long solid retention time in membrane bioreactor

A membrane bioreactor (MBR) with sludge retention time (SRT) of 300 days was maintained for over 2 years. Polypropylene microfiltration (MF) membrane with pore size of 0.2 <TEX>${\mu}m$</TEX> was used in the MBR system. The fouling behaviors of various sludge fractions from the MBR were studied and sub-divided resistances were analyzed. It was observed that <TEX>$R_{cp}$</TEX> was a dominant resistance during the filtration of activated sludge, contributing 63.0% and 59.6% to the total resistance for MBR and sequential batch reactor (SBR) respectively. On the other hand, <TEX>$R_c$</TEX> played the significant role during the filtration of supernatant and solutes, varying between 54.54% and 67.18%. Compared with <TEX>$R_{cp}$</TEX> and <TEX>$R_c$</TEX>, <TEX>$R_{if}$</TEX> was negligible, and <TEX>$R_m$</TEX> values remained constant at <TEX>$0.20{\times}10^{12}m^{-1}$</TEX>. Furthermore, resistances of all sludge fractions increased linearly with rising mixed liquor suspended solids (MLSS) concentration and growing trans-membrane pressure (TMP), while the relationship was inversed between fraction resistances and cross flow velocity (CFV). Among all fractions of activated sludge, suspended solid was the main contributor to the total resistance. A compact cake layer was clearly observed according to the field emission scanning electro microscopy (FE-SEM) images.