Filtration Flux Research Articles

Analysis of Serum Advanced Glycation Endproducts Reveals Methylglyoxal-Derived Advanced Glycation MG-H1 Free Adduct Is a Risk Marker in Non-Diabetic and Diabetic Chronic Kidney Disease

Accumulation of advanced glycation endproducts (AGEs) is linked to decline in renal function, particularly in patients with diabetes. Major forms of AGEs in serum are protein-bound AGEs and AGE free adducts. In this study, we assessed levels of AGEs in subjects with and without diabetes, with normal renal function and stages 2 to 4 chronic kidney disease (CKD), to identify which AGE has the greatest progressive change with decline in renal function and change in diabetes. We performed a cross-sectional study of patients with stages 2-4 CKD, with and without diabetes, and healthy controls (n = 135). Nine protein-bound and free adduct AGEs were quantified in serum. Most protein-bound AGEs increased moderately through stages 2-4 CKD whereas AGE free adducts increased markedly. Methylglyoxal-derived hydroimidazolone MG-H1 free adduct was the AGE most responsive to CKD status, increasing 8-fold and 30-fold in stage 4 CKD in patients without and with diabetes, respectively. MG-H1 Glomerular filtration flux was increased 5-fold in diabetes, likely reflecting increased methylglyoxal glycation status. We conclude that serum MG-H1 free adduct concentration was strongly related to stage of CKD and increased in diabetes status. Serum MG-H1 free adduct is a candidate AGE risk marker of non-diabetic and diabetic CKD.

Mitigation of ultrafiltration membrane fouling by a simulated sunlight-peroxymonosulfate system with the assistance of irradiated NOM

Oxidation pretreatments prior to ultrafiltration are hindered by the need for energy input and sludge disposal. Herein, a simulated sunlight-induced natural organic matter (NOM) for peroxymonosulfate (PMS) activation was used as pretreatment to alleviate ultrafiltration membrane fouling caused by NOM itself in the Songhua River water. When light intensity was over 100 mW/cm2, the pretreatment removed NOM effectively, characterized with UV254, dissolved organic carbon (DOC) and maximum fluorescent intensity (Fmax), and improved filtration flux. At 200 mW/cm2 light intensity and 0.5 mM PMS, 57.5% of UV254 and 18.5% of DOC were removed, and humic-like fluorescent component was degraded by 84%-94% while ∼60% for protein-like substance. Membrane flux was increased by 94%, and reversible and irreversible fouling resistances were reduced by 62.4% and 51.9%, respectively. Both total fouling index (TFI) and hydraulic irreversible fouling index (HIFI) were moderately correlated with the DOC, whereas they prominently correlated with the UV254 and the Fmaxs of all fluorescence components, which could be served as key indicators to predict and control membrane fouling. Mathematical modeling showed that the pretreatment alleviated the fouling in the membrane pores and cake layer. The simulated sunlight-induced NOM (3NOM* and eaq¯) could activate PMS to form active species, which enabled to oxidize high molecular weight (MW) substances and mineralize low MW compounds in NOM as well as hinder their linking with inorganic cations, thereby reducing organic and inorganic membrane fouling simultaneously. This study may provide a new strategy for decentralized potable water treatment, especially in a single household or community.

Hydrophilic Antimicrobial Polyethersulfone Membrane for Removal of Turbidity of Well-Water

Membrane-based technologies have been widely used for surface water treatment. Yet, many aspects of this technology can still be improved. This study aims to develop polyethersulfone (PES)-based phase-inverted membranes to improve the morphological structure, antimicrobial properties, and performance by incorporating Poloxamer 188 and patchouli oil as the dope solution additives. The performance of the membrane was assessed for filtration of well water and by evaluating the turbidity rejection. This study used a phase inversion technique in the membrane manufacturing process with PES, PES + P188 + 1 wt% PO, PES + P188 + 3 wt% PO, and PES + P188 + 7 wt% PO. The characteristics of the obtained membranes were studied in terms of structure and morphology, microbial growth prevention, hydrophilicity, filtration flux, and ability to reduce the turbidity of well water samples. Results show that the addition of Poloxamer 188 and patchouli oil in the dope solution turned the membrane more porous (up to 73.24% increase in porosity) and more hydrophilic (the water contact angle (WCA) was lowered from 70 to 37°). The additives also increased the antibacterial properties of the membrane, as shown by up to 97.5% reducing Escherichia coli colonies on the membrane surface. Overall, the results demonstrate significant improvements in the characteristics and performance of PES membranes by incorporating Poloxamer 188 co-polymer and patchouli oil as additives in the dope solution. The modified membrane was successfully applied to remove turbidity from a water sample. The turbidity parameters in well water samples could be fully reduced in nine out of ten samples by the membrane containing 7 wt% PO additives.

3D modeling of PVDF membrane aging using scanning electron microscope and OpenCV image analysis

The aging of membranes compromises their integrity and reduces the quality of filtered water. In the present study, we constructed three-dimensional (3D) models of polyvinylidene fluoride (PVDF) membranes to evaluate the effects of membrane aging. Virgin and used PVDF membrane images were obtained by field emission scanning electron microscopy (FE-SEM), and the size distribution of the PVDF spherulites was analyzed using a Python-OpenCV program. Assuming a random distribution, the 3D membrane models were assessed in hydraulic and particle tracing simulations using COMSOL Multiphysics®. Compared to virgin membranes, the PVDF spherulites in the 10-year-old used membranes were enlarged and sloughed off owing to repeated filtration and backwashing. The porosity, filtration flux, and particle retention of the used membranes varied significantly more than those of the virgin membranes. Although our results were constrained by the size of the 3D membrane models and overall small sample size, our study provides an empirical basis for the 3D modeling of membranes from SEM images and our method could be applied for the optimization of membrane structure and integrity for water treatment and purification.

Impacts of Calcium Addition on Humic Acid Fouling and the Related Mechanism in Ultrafiltration Process for Water Treatment.

Humic acid (HA) is a major natural organic pollutant widely coexisting with calcium ions (Ca2+) in natural water and wastewater bodies, and the coagulation-ultrafiltration process is the most typical solution for surface water treatment. However, little is known about the influences of Ca2+ on HA fouling in the ultrafiltration process. This study explored the roles of Ca2+ addition in HA fouling and the potential of Ca2+ addition for fouling mitigation in the coagulation-ultrafiltration process. It was found that the filtration flux of HA solution rose when Ca2+ concentration increased from 0 to 5.0 mM, corresponding to the reduction of the hydraulic filtration resistance. However, the proportion and contribution of each resistance component in the total hydraulic filtration resistance have different variation trends with Ca2+ concentration. An increase in Ca2+ addition (0 to 5.0 mM) weakened the role of internal blocking resistance (9.02% to 4.81%) and concentration polarization resistance (50.73% to 32.17%) in the total hydraulic resistance but enhanced membrane surface deposit resistance (33.93% to 44.32%). A series of characterizations and thermodynamic analyses consistently suggest that the enlarged particle size caused by the Ca2+ bridging effect was the main reason for the decreased filtration resistance of the HA solution. This work revealed the impacts of Ca2+ on HA fouling and demonstrated the feasibility to mitigate fouling by adding Ca2+ in the ultrafiltration process to treat HA pollutants.

Comparison of the formation, filtration performance, and structural characteristic of self-forming dynamic membranes under constant transmembrane pressure and constant filtration flux

The formation and filtration of self-forming dynamic membranes (SFDMs) can be affected by multiple factors, such as the operating conditions and sludge properties in membrane bioreactors. There has been limited research on the effects of the constant transmembrane pressure and constant filtration flux on the stable filtration of dynamic membranes. In the present study, a large-pore stainless steel mesh (70 µm pore size) was used as the support material for dynamic membrane formation to explore the formation, filtration performance, and structural characteristics of two dynamic membranes, P-SFDM (filtration under constant transmembrane pressure) and J-SFDM (filtration under constant flux), with the same initial filtration flux. The results showed that the stable filtration period of J-SFDM went up to 22.5 h, which was significantly longer than that of P-SFDM (5.5 h) with a higher resistance growth speed. The blocking process of the P-SFDM membrane conformed to the complete blocking model, whereas that of the J-SFDM membrane conformed to the standard blocking model in the initial stage and follows the intermediate blocking model in the later stage. Besides, the P-SFDM cake layer had a higher extracellular polymer content and smaller particle size (106 ± 2 mg·g−1 VSS, 546 ± 63 µm) than that of the J-SFDM cake layer (89 ± 3 mg·g−1 VSS, 615 ± 51 µm). During a 39-day continuous long-term operation, the energy consumptions per ton of water for J-SFDM and P-SFDM were 0.14 kw·h·t−1 and 0.19 kw·h·t−1, respectively. The above results show that the J-SFDM has a longer stable filtration period with lower energy consumption per ton of water.

Fabrication of Gd2O3/PSF Membranes via Aqueous Phase Inversion Method

This study aimed to investigate the effect of Gadolinium oxide (Gd2O3) concentration (0.5%, 1%, and 2%) on the performance of polysulfone (PSF) membrane. The membranes were fabricated by a common phase inversion method. The performance of membranes was determined based on pure water flux, bovine serum albumin (BSA) permeation test. These fabricated membranes were characterized by FTIR and contact angle measurements. The highest BSA rejection was 53%. The optimum membrane (2 % wt Gd2O3 /17 % wt PSF) in this study was determined by PSF 17% which successfully exhibited 53% rejection with filtrate flux for about 8.7 L/m2.h at a pressure of 10 bar.

Suppressing transmembrane-pressure rise by pulse dosing of submicron super-fine powdered activated carbon: Effects of filtration flux, coagulant types, and coagulant-dose timing during precoating

Submicron-sized powdered activated carbon (SSPAC, diameter 200 nm) dosed in a pulse after coagulation pretreatment has recently been found to effectively mitigate membrane fouling and thus to suppress the rise of transmembrane pressure (TMP) in the microfiltration process because SSPAC has a higher capacity to adsorb membrane foulants, such as natural organic matter, than conventional PAC and a precoat layer formed by SSPAC on the membrane surface retards membrane fouling. This study investigated the effects of the filtration flux during precoating, the timing of coagulant dosing, and the types of coagulants on the suppression of TMP rise by pulse-dosed SSPAC. The TMP rise was insensitive to the filtration flux during precoating. However, the efficacy of the SSPAC was sensitive to the use of the coagulant polyaluminum-chloride (PACl). Unlike pulse dosing of SSPAC, pulse dosing of coagulant led to excessive aggregation and settling of SSPAC and insufficient formation of a precoating layer. The best filterability was achieved when the coagulant was dosed continuously in the entire operation period. It is also effective to use treated water for feeding during the preparation stage. For sulfated PACl, high basicity (70 %), with its high charge neutralization capacity, was preferred to medium basicity (50 %). Meanwhile, the TMP rise was more effectively suppressed by non-sulfated PACl with a low-to-medium basicity (20–40 %) than zero or high basicity (70 %). This behavior was explained by the fact that, as the basicity increases, hydrolysis of the coagulants is lessened, but the charge neutralization effect becomes stronger.

Microbial Responses to Various Types of Chemical Regents during On-Line Cleaning of UF Membranes.

Ultrafiltration is widely used to treat various environmental waters, and on-line membrane cleaning with various chemical reagents is frequently employed to sustain the filtration flux. However, the residue of cleaning agents in the ultrafiltration system is unavoidable, which may affect microbiological properties and biofilm formation during the next-round filtration. By investigating the changes in microbial characteristics, and their biofouling behaviors after exposure to HCl, NaOH, NaClO, citric acid (CA), and sodium dodecyl sulfonate (SDS), this study fills a knowledge gap in microbial responses to various types of chemical cleaning agents in an ultrafiltration system. The result shows that HCl, NaOH, and NaClO affect the bacterial properties and subsequent attachment on the membrane surface, while CA and SDS have no obvious influence on microorganisms. Specifically, HCl, NaOH, and NaClO reduce the hydrophobicity and mean size of suspended microorganisms, increase the extracellular polymeric substances (EPS) release, and trigger intracellular reactive oxygen species (ROS) generation, resulting in the death of a large quantity of microorganisms. Due to the self-protecting strategy, plenty of living cells aggregate on the membrane surface and form a cake layer with a stratified structure, causing more severe membrane biofouling.

Assessment of probability of failure on rainfall-induced shallow landslides at slope scale using a physical-based model and fuzzy point estimate method

Shallow hillslope failure caused by rainfall is characterized by complex soil hydrology and mechanical behavior. It is important to understand the hydraulic behavior of hillslopes and quantify the effect of the uncertainty of mechanical parameters on hillslope stability for forewarning and hillslope management. Intra-hole deformation and displacement were record for the hillslope of the Babaoliao collapse site in the Chiayi County, as a case study. The fuzzy point estimation method and physical-based model were combined with the local factor of safety (LFS) theory to calculate the internal local factor of safety of the hillslope. A reliability analysis was then performed to determine the failure probability at different depths. Historical rainfall events were used to validate the model and predict the development of the failure probability for different rainfall patterns with the same warning rainfall. The results revealed that the failure probability model could effectively predict the area of hillslope instability and its changes over time and space. Different rainfall patterns affected the infiltration flux, leading to the difference in hillslope failure time. The delayed rainfall pattern had a significant impact on the time of slope instability, and shallow collapse was most likely to occur earlier. This study can be used as a reference for developing future hillslope warnings.

Self-Organization of Graft Copolymers and Retortable iPP-Based Nanoporous Films Thereof

Polyolefins might become inexpensive alternatives to the existing membranes based on polyethersulfone. Here, we disclose the production of retortable, well-defined polypropylene (PP)-based nanoporous films derived from amphiphilic graft copolymer precursors. The graft copolymers, containing a polypropylene backbone and polyester grafts, were obtained by grafting lactones, specifically δ-valerolactone and ε-caprolactone, from well-defined randomly functionalized poly(propylene-co-10-undecen-1-ol) as a macroinitiator. Depending on the composition, the graft copolymers self-assemble into droplet, cylindrical, lamellar, or interconnected two-phase morphologies. Functional mesoporous iPP-based films were fabricated by the selective degradation of the polyester blocks of the copolymers. Their structure and morphology were studied using atomic force microscopy (AFM), scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), and solid-state NMR, while the mesoporosity was assessed by nitrogen sorption experiments. The pore size of the films is strongly influenced not only by the volume fraction of the copolymer blocks but unexpectedly also by the topology (i.e., number of grafts) of the graft copolymer, as was confirmed by computational modeling studies using the dynamic density functional theory (DDFT) engine within the Culgi software. This work provides a conclusive answer on how the morphology of iPP-based graft copolymers is tuned by the copolymer composition and the amount and length of the grafted polyester blocks. Filtration tests and flux determination demonstrated that such structurally well-defined mesoporous products could be considered for the development of ultrafiltration membranes while the chemical resistance and sterilization tests revealed their robust performance and suitability for water purification applications.

TiO2 ceramic membrane decorated with Fe3O4–Ag composite nanoparticles for produced water treatment

This study focused on the surface modification of commercial TiO2 membranes with Fe3O4 decorated silver (Ag) nanoparticles (Fe3O4–Ag) via chemical attachment. Firstly, the Ag concentration on Fe3O4 was optimized, and different composites were prepared and characterized. Secondly, the optimal composite was used to prepare novel TiO2/Fe3O4–Ag ceramic membranes via surface coating through tetraethyl orthosilicate (TEOS) crosslinking. The membranes were characterized using SEM, EDX, FTIR, XRD, and contact angle. Biofouling resistance of the membranes was investigated using the Coomassie Blue dye method. The coated membranes were tested for water flux, chemical oxygen demand (COD) rejection, and biofouling resistance. Results showed that all coated membranes exhibited higher water flux. For example, the membrane with a 1.25 wt% Fe3O4–Ag coating showed the highest filtration flux of 1445 L/m2h (LMH) compared to the pristine membrane (379 LMH) without compromising the COD rejection. The resistance of the membrane to biofouling increased with the increase of Fe3O4–Ag nanoparticle concentration. The obtained results demonstrate the great potential of TiO2/Fe3O4–Ag ceramic membranes for the treatment of produced water.

Crosslinked biomimetic coating modified stainless-steel-mesh enables completely self-cleaning separation of crude oil/water mixtures

The development of high-flux, durable and completely self-cleaning membranes is highly desired for separation of massive oil/water mixtures. Herein, differently crosslinked poly(2-methacryloyloxylethyl phosphorylcholine) (PMPC) brush grafted stainless steel mesh (SSM) membranes (SSM/PMPCs) were fabricated by integrating of mussel inspired universal adhesion and crosslinking chemistry with surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET-ATRP). The durability and self-cleaning performance of the prepared SSM membranes were evaluated by separating sticky crude oil/water mixtures in a continuous recycling dead-end filtration device. The water filtration flux driven by gravity reached 60,000 L⋅m−2⋅h−1 with a separation efficiency of over 99.98%. Furthermore, zero-flux-decline was observed during a 5 h continuous filtration when assisted by mechanical stirring. More significantly, such a completely self-cleaning separation of the well crosslinked SSM/PMPC2 membrane under optimized flux and stirring conditions had been operated cumulatively for 190 h in 30 days without any additional cleaning. These significant advances are more promising for practical applications in crude oil-contaminated water treatments and massive oil/water mixture separation.

High-strength and anti-bacterial BSA/carboxymethyl chitosan/silver nanoparticles/calcium alginate composite hydrogel membrane for efficient dye/salt separation

In order to solve the problems of poor mechanical property, non-antibacterial and low flux of calcium alginate (CaAlg) membrane, silver nanoparticles (AgNPs) were synthesized with bovine serum albumin (BSA) and carboxymethyl chitosan (CMCS) for improving CaAlg membrane in this paper. Meanwhile, the dispersion property of silver nanoparticles and the mechanical property, thermal stability, antibacterial property and filtration efficiency of the composite membrane were explored. The results illustrated CMCS observably strengthened the mechanical property and thermal stability of the composite membrane, and AgNPs endowed the composite membrane with excellent antibacterial property. The flux of the BSA/CMCS/AgNPs/CaAlg composite membrane was raised compared to CaAlg membrane. Finally, the viscose fiber/polyethylene terephthalate fiber (VF-PET) nonwoven fabric was introduced as the support layer to further improve the filtration flux and mechanical property of the composite membrane. VF-PET/BSA/CMCS/AgNPs/CaAlg membrane had a rejection rate of over 99.0 % for dye molecules and <9.0 % for salt ions, while the flux maintained 38.5 L·m−2·h−1. Furthermore, VF-PET/BSA/CMCS/AgNPs/CaAlg membrane also had excellent separation effect on actual dye wastewater. The separation of dye and salt by the membrane mainly depended on the screening mechanism of membrane pore size, rather than adsorption. The composite membrane had an outstanding performance on the separation of dye molecules and inorganic salt ions.

Encapsulating Amidoximated Nanofibrous Aerogels within Wood Cell Tracheids for Efficient Cascading Adsorption of Uranium Ions.

Continuous filtering adsorption has drawn growing interest in the exploration of uranium resources in seawater and reduction in the environmental risks of uraniferous wastewater from nuclear industries. For most filtering adsorbents, repeated filtration, high membrane thickness, and high pressure are normally essential to achieve both a high rejection ratio and high filtration flux. Herein cellulose fibrils were preferentially exfoliated from the lignin-poor layer of secondary cell walls of balsa wood during an in situ amidoximation process. By maintaining honeycomb-like cellular microstructures and cellulose aerogel stuffing in their cell tracheids, the resultant nanowoods showed superior mechanical properties (e.g., compressive strength ∼1.3 MPa in transverse direction) with large surface areas (∼80 m2 g-1). When their cell tracheids were aligned perpendicular to the flow and the edges sealed with a thermoset polymer, they could serve as efficient and high-pressure filtration membranes to capture aquatic uranium ions. In analogy to a typical cascading filtration system, the filtrate passed successively the layered-organized cell tracheids through abundant micropores on their cell walls, enabling a high rejection ratio of >99% and flux of ∼920 L m-2 h-1 under pressure up to 6 bar (membrane thickness of 2 mm). Thus, this study not only provides an in situ approach to producing robust woods with functional nanocellulose encapsulated into their cell tracheids but also offers a sustainable route for high-efficiency extraction of aqueous uranium.

Cell Membrane Mimetic Coating for Excellent Antifouling, Antibacterial Corrosion, and Self‐Cleaning Separation of Massive Oil–Water Mixtures

AbstractMassive oil–water mixtures produced from both industries and frequent oil spill incidents have threatened water ecosystems. A highly efficient separation membrane with ultrahigh filtration flux and excellent antifouling performance is created to deal with oil–water mixtures. The filtration membrane is fabricated by anchoring a phosphorylcholine copolymer (PMEN) on polydopamine (PDA)‐precoated stainless steel mesh (SSM) surfaces, forming a durable cell outer membrane mimetic coating. The as‐prepared SSM/PDA/PMEN membranes exhibit superhydrophilicity and high separation efficiency (≥99.98%) for different oil–water mixtures. Furthermore, the water flux of separating 30 v/v% crude oil–water mixture can reach as high as 70 000 L m–2 h–1 and remains higher than 30 000 L m–2 h–1 without any additional washing during 100 cycles of successive separations in a dead‐end filtration device. More importantly, substantial corrosion of stainless steel surfaces by bacteria is prevented on the cell membrane mimetic coating by its excellent antibacterial adhesion performance. These unprecedented underwater anticrude oil‐fouling and antibacterial‐corrosion properties, as well as the ultrahigh flux and high separation efficiency of SSM/PDA/PMEN membranes, are highly promising in the cleanup of massive oily water and oil spills in the near future.

New insight into hydrodynamic and cake erosion mechanism during rotating-disk dynamic microfiltration of concentrated bentonite suspensions at different salinity conditions

The present study investigates the dynamic filtration of concentrated slurry fluids containing colloidal clay particles under different salinity, shear flow, and flux rate conditions. The dynamic filtration study was carried out by the filtration cell equipped with a rotating disk to apply shear stress over the membrane surface. A 3D CFD simulation has been implemented to model the hydrodynamic flows inside the filtration cell to obtain the wall shear stress (WSS) on the membrane surface at different disk rotation speeds. The thickness and surface patterns of fouling were captured utilizing a surface profilometer. First, the cake-filtration model was used to predict the flux rate and fouling thickness under static filtration. Then, the corresponding filtrate flux at stabilized cake thickness under shear flow conditions was calculated. The results showed that increasing the suspension salinity causes the reduction of rheological properties and increases the cake permeability due to the compression of the electrical double layer around clay particles. The results also revealed that increasing the flux rate condenses the cake and reduces erosion. Finally, a model for predicting the rate of fouling removal during dynamic filtration was developed using nonlinear regression. The results showed that a sigmoidal function with appropriate accuracy (R2>0.96) could describe fouling thickness patterns with WSS. Moreover, the mean cake thickness decreased by 80% as the WSS increased from 0 to 2 Pa, where the rotating disk speed increased from 0 to 500 rpm.

Can prechlorination improve the permeate flux and water quality of gravity-driven membrane (GDM) filtration?

Gravity-driven membrane (GDM) filtration is currently limited by the relatively low permeate flux and poor water quality. This study was aimed to investigate the effects of prechlorination (3 and 5 mgCl2/L) on the permeate flux and water quality in GDM filtration by analyzing the compositions and morphologies of the fouling layer and by evaluating virus removal and trihalomethane (THM) formation for short (7 cycles) and long (32 cycles) periods. Prechlorination showed an increased permeate flux, contributing to enhanced cumulative water production (15–68%), which was achieved by lowering the extracellular polymeric substances (EPS) content (14–31%) and the formation of a relatively thinner and looser fouling layer. Prechlorination effects lessened with longer GDM operation time owing to bacterial regrowth and formation of a thick (178–227%) and dense (57–66%) fouling layer. It also changed the dominant phylum in the eukaryotic community and limited its activities in the fouling layer. In terms of the permeate water quality, the prechlorination ensured microbial safety with a 3.2 log10 reduction of MS2 bacteriophage and negligible formation of THMs. These results demonstrate the potential of using prechlorination in GDM filtration for sustainable drinking water treatment.

Effect of module geometry on the sustainable flux during microfiltration of precipitated IgG

Recent increases in monoclonal antibody titer from Chinese Hamster Ovary cell culture has led to renewed interest in precipitation for the initial capture/purification of these high-value proteins. In this work, we examined the effect of the membrane module geometry on the sustainable flux and fouling mechanisms using human serum Immunoglobulin G (IgG) precipitated with 10 mM zinc chloride and 7 w/v % polyethylene glycol as a model system. The sustainable flux was evaluated using flux stepping experiments for both open channel cassettes and hollow fiber membrane modules. The hollow fiber modules had relatively low sustainable flux due to clogging of the fibers at the module inlet, with this behavior confirmed using both SEM imaging and hydraulic permeability data for the fouled modules. In contrast, the open channel cassettes showed no evidence of channel clogging, enabling continuous operation for at least 24 h at a filtrate flux below the experimentally determined sustainable flux. These results provide important insights into the origin of the sustainable flux during tangential flow filtration of precipitated proteins, greatly facilitating the design of precipitation-filtration processes for continuous purification of monoclonal antibody products.

Investigation of membrane fouling and mechanism induced by extracellular organic matter during long-term exposure to pharmaceuticals and personal care products

This study investigated ultrafiltration membrane fouling by extracellular organic matter (EOM) and the mechanism operating during long-term exposure to pharmaceuticals and personal care products. The results indicated that carbamazepine and diclofenac in algal-laden water altered the filtration flux and membrane fouling by EOM. Exposure to low-concentration carbamazepine (0.25 μg/L) improved the filtration flux and the total (Rtot) and reversible fouling resistance (Rc), whereas the filtration flux and Rtot and Rc were reduced when EOM was used during long-term exposure to high carbamazepine concentrations (>1 μg/L). Both Rtot and Rc were increased when algae were exposed to 0.25 μg/L diclofenac, whereas the filtration flux and Rtot and Rc were alleviated when algae were exposed to >1 μg/L diclofenac. Moreover, carbamazepine and diclofenac (0.25 μg/L − 1000 μg/L) in water enhanced the irreversible fouling resistance (Rb) when ultrafiltration was used to treat algal-laden waters. The mechanism indicated that membrane fouling induced by standard blocking was transformed to complete blocking when EOM was exposed to high levels of carbamazepine (>0.25 μg/L) in the initial filtration process, whereas cake layer formation played an important role during the later filtration process; with low carbamazepine levels (0.25 μg/L), standard blocking of EOM was dominant during the entire filtration process. The membrane fouling mechanism also changed when algal-laden waters were exposed to diclofenac, the membrane fouling was transformed from complete blocking to standard blocking when DFC was present in the initial filtration process, whereas cake layer formation exerted an important role during the late filtration process. This research provides important information on the long-term risks caused by pharmaceutical and personal care products and potential threats to membrane treatment.