Ultrafiltration Membrane Module Research Articles

On-site filtration of large sample volumes improves the detection of opportunistic pathogens in drinking water distribution systems.

In this study, we compared conventional vacuum filtration of small volumes through disc membranes (effective sample volumes for potable water: 0.3-1.0 L) with filtration of high volumes using ultrafiltration (UF) modules (effective sample volumes for potable water: 10.6-84.5 L) for collecting bacterial biomass from raw, finished, and tap water at seven drinking water systems. Total bacteria, Legionella spp., Legionella pneumophila, Mycobacterium spp., and Mycobacterium avium complex in these samples were enumerated using both conventional quantitative PCR (qPCR) and viability qPCR (using propidium monoazide). In addition, PCR-amplified gene fragments were sequenced for microbial community analysis. The frequency of detection (FOD) of Legionella spp. in finished and tap water samples was much greater using UF modules (83% and 77%, respectively) than disc filters (24% and 33%, respectively). The FODs for Mycobacterium spp. in raw, finished, and tap water samples were also consistently greater using UF modules than disc filters. Furthermore, the number of observed operational taxonomic units and diversity index values for finished and tap water samples were often substantially greater when using UF modules as compared to disc filters. Conventional and viability qPCR yielded similar results, suggesting that membrane-compromised cells represented a minor fraction of total bacterial biomass. In conclusion, our research demonstrates that large-volume filtration using UF modules improved the detection of opportunistic pathogens at the low concentrations typically found in public drinking water systems and that the majority of bacteria in these systems appear to be viable in spite of disinfection with free chlorine and/or chloramine.IMPORTANCEOpportunistic pathogens, such as Legionella pneumophila, are a growing public health concern. In this study, we compared sample collection and enumeration methods on raw, finished, and tap water at seven water systems throughout the State of Minnesota, USA. The results showed that on-site filtration of large water volumes (i.e., 500-1,000 L) using ultrafiltration membrane modules improved the frequency of detection of relatively rare organisms, including opportunistic pathogens, compared to the common approach of filtering about 1 L using disc membranes. Furthermore, results from viability quantitative PCR (qPCR) with propidium monoazide were similar to conventional qPCR, suggesting that membrane-compromised cells represent an insignificant fraction of microorganisms. Results from these ultrafiltration membrane modules should lead to a better understanding of the microbial ecology of drinking water distribution systems and their potential to inoculate premise plumbing systems with opportunistic pathogens where conditions are more favorable for their growth.

Investigation of Different Pre-Treatment Techniques and 3D Printed Turbulence Promoter to Mitigate Membrane Fouling in Dairy Wastewater Module.

This study investigates the enhancement of dairy wastewater treatment using chemical and physical pre-treatments coupled with membrane separation techniques to reduce membrane fouling. Two mathematical models, namely the Hermia and resistance-in-series module, were utilized to comprehend the mechanisms of ultrafiltration (UF) membrane fouling. The predominant fouling mechanism was identified by fitting experimental data into four models. The study calculated and compared permeate flux, membrane rejection, and membrane reversible and irreversible resistance values. The gas formation was also evaluated as a post-treatment. The results showed that the pre-treatments improved UF efficiency for flux, retention, and resistance values compared to the control. Chemical pre-treatment was identified as the most effective approach to improve filtration efficiency. Physical treatments after microfiltration (MF) and UF showed better fluxes, retention, and resistance results than ultrasonic pre-treatment followed by UF. The efficacy of a three-dimensionally printed (3DP) turbulence promoter was also examined to mitigate membrane fouling. The integration of the 3DP turbulence promoter enhanced hydrodynamic conditions and increased the shear rate on the membrane surface, shortening filtration time and increasing permeate flux values. This study provides valuable insights into optimizing dairy wastewater treatment and membrane separation techniques, which can have significant implications for sustainable water resource management. The present outcomes clearly recommend the application of hybrid pre-, main- and post-treatments coupled with module-integrated turbulence promoters in dairy wastewater ultrafiltration membrane modules to increase membrane separation efficiencies.

UF膜モジュールを用いたイシクラゲ由来フィコビリタンパク質の濃縮の予測

Phycobiliprotein (PB) produced by cyanobacteria exhibits an anti-inflammatory effect and anti-cancer effect, and is expected to be applied as pharmaceuticals. In this study, a PB-containing solution from Nostoc commune was concentrated and separated by an ultrafiltration (UF) membrane module (nominal molecular weight limit (NMWL) 150 kDa, 30 kDa and 10 kDa). When the PB-containing solution was permeated through an UF membrane module of NMWL 10 kDa at 0.07 MPa, the total protein content was concentrated up to 10 times in 30 minutes. To simulate the change in the concentration for the concentrate in the scaled-up treatment, the parameters of the formed cake layer were determined by a mathematical model. The concentration performance of the UF membrane modules was evaluated using the obtained parameters, indicating that the 150 kDa NMWL UF membrane modules were able to concentrate 100 liters of PB-containing solution by 10 times in 15 hours. The 30 kDa and 10 kDa NMWL UF membrane modules showed the possibility of PB separation, as well as protein concentration. The productivity of PB calculated by flux and selectivity was highest for the 30 kDa NMWL UF membrane module.

Chinese wastewater treatment facility uses Toray membrane technology

A wastewater filtration system, which came on stream in July this year at the Yindingzhuang Wastewater Treatment Plant, China, employs hollow-fibre ultrafiltration (UF) membrane modules developed by Japan’s Toray Industries Inc.

CFD simulations of flow fields during ultrafiltration: Effects of hydrodynamic strain rates with and without a particle cake layer on the permeation of mobile genetic elements

Membrane ultrafiltration (UF) combined with inline dosing of powdered activated carbon (PAC) are popular hybrid processes for water reclamation. However, hydrodynamic forces can allow mobile genetic elements (MGEs) that are larger than the membrane pore size to penetrate through UF membranes. The flow fields in the feed channel of a dead-end UF membrane module were modelled using computational fluid dynamics (CFD) in order to analyze shear and elongational strain rates and associated potential hydrodynamic effects by a PAC particle layer on MGE retention. The most significant magnitudes of strain rates occurred within a distance of tens of nanometers from the membrane surface, meaning that this is where significant deformation of MGEs occurs. Since flow fields were not considerably altered at the membrane surface, the presence of the PAC particle layer was expected to have a negligible impact on the permeation of MGEs through UF membrane pores.

Integrated flow anodic oxidation and ultrafiltration system for continuous defluorination of perfluorooctanoic acid (PFOA)

While flow anodic oxidation systems can efficiently generate hydroxyl radicals (·OH) and significantly enhance direct electron transfer (DET) processes that result in the oxidation of target contaminants via the charge percolating network of flow anode particles, challenges remain in constructing a flow anodic oxidation system that can be operated continuously with stable performance. Here we incorporate an ultrafiltration (UF) membrane module into the flow anodic oxidation system and achieve the continuous defluorination of perfluorooctanoic acid (PFOA) for 12 days with high efficiency (94.1%) and reasonable energy consumption (38.1 Wh mg–1) compared to other advanced oxidation processes by using a mixture of conducting TixO2x-1 and Pd/CNT particles as the flow anode. The results indicate that DET, ·OH mediated oxidation and adsorption processes play critical roles in the degradation of PFOA during the flow anodic oxidation processes. The synergistic effect of the TixO2x-1 and Pd/CNT particles enhances the defluorination efficiency by 3.2 times at 4.5 V vs Ag/AgCl compared to the control experiment (no flow anode particles present) and promotes the release of F– into solution while other intermediate products remain adsorbed to the surface of the Pd/CNT particles. Although the Pd/CNT particles were oxidized after the long-term operation, no obvious Pd ion leakage into solution was observed. Results of this study support the feasibility of continuous operation of a flow anode/UF system with stable performance and pave the way for the translation of this advanced oxidation technology to practical application.

A Pilot-Scale Treatment of Steel Plant Wastewater by PVDF Hollow Fiber Ultrafiltration Membrane with Low Packing Density

The treatment of wastewater from the iron and steel industry is difficult due to its complex and changeable characteristics. This paper introduces the application of polyvinylidene fluoride (PVDF)-pressurized ultrafiltration membrane with low packing density that produced via thermally induced phase separation (TIPS) in wastewater of iron and steel industry, to study the effects of packing density of ultrafiltration membrane modules as well as the membrane performance under different operation conditions, in order to provide guidance for the subsequent development of other ultrafiltration applications in wastewater of iron and steel. The results show a significant positive effect of smaller packing density on the transmembrane pressure difference (TMP) reducing and higher permeability. Under 30 min filtration cycle and 65 L m−2 h−1 (LMH) operation flux, the permeability can be stabilized to 200 L/(m2·h)/0.1 MPa, which is two times higher than that of the membrane module with 0.3 m2/m3 higher packing density under the same condition. It is obvious that compared with enhanced flux maintenance (EFM), chemically enhanced backwash (CEB) is a more effective cleaning method for iron and steel wastewater, which maintains TMP (30 kPa) without any significant increase under the premise of ensuring the high-flux (65 LMH) operation. The results also suggest reasonable parameters based on the test water quality, which include the filtration cycle and operation flux. The scanning electron microscopy (SEM) analysis and the turbidity of the permeate show that the ultrafiltration membrane has good intercept ability and high anti-pollution performance.

Controlling the hydraulic resistance of membrane biofilms by engineering biofilm physical structure

The application of membrane technology for water treatment and reuse is hampered by the development of a microbial biofilm. Biofilm growth in micro-and ultrafiltration (MF/UF) membrane modules, on both the membrane surface and feed spacer, can form a secondary membrane and exert resistance to permeation and crossflow, increasing energy demand and decreasing permeate quantity and quality. In recent years, exhaustive efforts were made to understand the chemical, structural and hydraulic characteristics of membrane biofilms. In this review, we critically assess which specific structural features of membrane biofilms exert resistance to forced water passage in MF/UF membranes systems applied to water and wastewater treatment, and how biofilm physical structure can be engineered by process operation to impose less hydraulic resistance (“below-the-pain threshold”). Counter-intuitively, biofilms with greater thickness do not always cause a higher hydraulic resistance than thinner biofilms. Dense biofilms, however, had consistently higher hydraulic resistances compared to less dense biofilms. The mechanism by which density exerts hydraulic resistance is reported in the literature to be dependant on the biofilms’ internal packing structure and EPS chemical composition (e.g., porosity, polymer concentration). Current reports of internal porosity in membrane biofilms are not supported by adequate experimental evidence or by a reliable methodology, limiting a unified understanding of biofilm internal structure. Identifying the dependency of hydraulic resistance on biofilm density invites efforts to control the hydraulic resistance of membrane biofilms by engineering internal biofilm structure. Regulation of biofilm internal structure is possible by alteration of key determinants such as feed water nutrient composition/concentration, hydraulic shear stress and resistance and can engineer biofilm structural development to decrease density and therein hydraulic resistance. Future efforts should seek to determine the extent to which the concept of “biofilm engineering” can be extended to other biofilm parameters such as mechanical stability and the implication for biofilm control/removal in engineered water systems (e.g., pipelines and/or, cooling towers) susceptible to biofouling.

A mini-module with built-in spacers for high-throughput ultrafiltration

Ultrafiltration membrane modules suffer from a permeate flow decrease arising during filtration and caused by concentration polarization and fouling in, e.g., fermentation broth purification. Such performance losses are frequently mitigated by manipulating the hydrodynamic conditions at the membrane–fluid interface using, e.g., mesh spacers acting as static mixers.This additional element increases manufacturing complexity while improving mass transport in general, yet accepting their known disadvantages such as less transport in dead zones. However, the shape of such spacers is limited to the design of commercially available spacer geometries. Here, we present a methodology to design an industrially relevant mini-module with an optimized built-in 3D spacer structure in a flat-sheet ultrafiltration membrane module to eliminate the spacer as a separate part. Therefore, the built-in structures have been conceptually implemented through an in-silico design in compliance with the specifications for an injection molding process. Ten built-in structures were investigated in a digital twin of the mini-module by 3D-CFD simulations to select two options, which were then compared to the empty feed channel regarding mass transfer. Subsequently, the simulated flux increase was experimentally verified during bovine serum albumin (BSA) filtration. The new built-in sinusoidal corrugation outperforms conventional mesh spacer inlays by up to 30% higher permeation rates. The origin of these improvements is correlated to the flow characteristics inside the mini-module as visualized online and in-situ by low-field and high-field magnetic resonance imaging velocimetry (flow-MRI) during pure water permeation.

Monitoring of hollow fiber module velocity field and fouling inside individual fibers using benchtop MRI

Ultrafiltration (UF) membrane modules are a viable pre-treatment technology for reverse osmosis processes; they however are susceptible to fouling. In the current study, we demonstrate the use of benchtop MRI to provide quantitative structural and velocity images of an UF membrane module showing velocity inside each individual fiber and proceed to provide unique insights into both subsequent fouling and cleaning events. The module consists of 400 fibers, these all were correctly identified from the MRI images based on an implemented fiber identification algorithm. Velocity imaging of the UF module, revealed significant water flow in only 91% of the fibers. Following fouling with a calcium alginate gel, only 73% of the fibers were observed to be active which only recovered to 79% on application of a cleaning protocol using acetic acid. Fouling was clearly isolated to specific fibers in which flow was effectively eliminated; this is not consistent with the assumption of uniform fouling deposition on the inner fiber walls. This also restricts the access of cleaning solutions which effectively by-pass the fouled fibers. This level of novel, quantitative insight is available on benchtop MRI equipment, which displays significant promise for further hollow fiber UF module design, manufacturing and fouling development and control studies.

Response of microalgae Chlorella vulgaris to Cr stress and continuous Cr removal in a membrane photobioreactor

This study evaluated the toxicity of Cr(VI) to microalgae Chlorella vulgaris, and its removal by continuous microalgae cultivation in membrane photobioreactor (MPBR). Batch cultivation in photobioreactors showed that low concentration of Cr(VI) (0.5 and 1.0 mg L−1) stimulated the growth of C. vulgaris, while 2.0 and 5.0 mg L−1 Cr(VI) in the wastewater significantly inhibited the growth of C. vulgaris. Superoxide dismutase and catalase activities that represented cellular antioxidant capacity significantly increased at 0.5 and 1.0 mg L−1 Cr(VI), and then gradually decreased with the continuous increase of Cr(VI) concentration. The content of malondialdehyde, which represents the degree of cellular oxidative damage, increased with the increase of Cr(VI) concentration and reached the peak value at 2.0 mg L-1 Cr(VI). C. vulgaris was then cultured in MPBR equipped with hollow-fiber ultrafiltration membrane module to achieve continuous removal of Cr from wastewater. With the in-situ solid-liquid separation function of the membrane module, solid retention time (SRT) and hydraulic retention time (HRT) of the reactor could be controlled separately. Experimental results showed that both SRT and HRT had significant effects on the algal biomass production and pollutants removal. During the continuous operation, MPBR achieved a maximum total Cr reduction of 50.0% at HRT of 3-day and SRT of 40-day, and a maximum volumetric removal rate of total Cr of 0.21 mg L−1 d−1 at HRT of 2-day and SRT of 40-day.

CFD study on the performance of hollow fiber ultrafiltration membrane modules with different fiber arrangement

CFD study on the performance of hollow fiber ultrafiltration membrane modules with different fiber arrangement

Enhanced alleviation of ultrafiltration membrane fouling by regulating cake layer thickness with pre-coagulation during drinking water treatment

Ultrafiltration (UF) membrane modules are static in membrane tanks; thus, result in the continuous development of a cake layer and serious membrane fouling. Thickness regulation is the most convenient method to solve this owing to the looseness induced by flocs. Recently, integrated membrane technology is increasingly being applied due to its high pollutant removal efficiency and low space requirements. Herein, with the injection of Fe-based flocs, the UF membrane performance was investigated with module rotation in the presence of humic acid (HA) and south-to-north water in China. The obtained results showed that the outer cake layer was easily shed away owing to the strong flow shear force. The thickness of the cake layer decreased and membrane fouling was significantly alleviated. The faster the rotation speed, the thinner the cake layer and the lower the membrane fouling was. However, the reduction rate of the cake layer thickness decreased as the rotation speed increased owing to the high density of the inner cake layer. Although both the rotation speed and rotation time played an important role in reducing the membrane fouling, the removal efficiency of HA remained constant, and the cake layer tended to be the main fouling mechanism; thus, indicating that module rotation is beneficial to the integrated technology. Owing to the smaller particle size and higher positive charge of flocs formed under an acidic condition, more negatively charged HA molecules were adsorbed, and the UF membrane performance was superior to that in an alkaline condition. Raw water experiments further confirmed the excellent UF membrane performance. Based on this, the proposed technology has great potential for wide applications in rural areas, particularly with the rapid development of clean energy (e.g., solar energy) and intelligent water services.

Poultry slaughterhouse wastewater treatment using a static granular bed reactor coupled with single stage nitrification-denitrification and ultrafiltration systems

This study evaluated the performance of a lab-scale poultry slaughterhouse wastewater (PSW) treatment system consisting of a static granular bed reactor (SGBR) coupled with single stage nitrification-denitrification (SND) bioreactor and ultrafiltration membrane module (ufMM) systems. The feasibility of treating PSW to a water quality standard compliant with industrial wastewater discharge standards was investigated. The SGBR was operated at hydraulic retention times (HRTs) ranging from 24 to 96 h and organic loading rates (OLRs) ranging from 0.73 to 12.49 g COD/L.day, for 138 days. The chemical oxygen demand (COD), total suspended solids (TSS), biological oxygen demand (BOD5) and fats, oils and grease (FOG) removal efficiencies achieved by the SGBR averaged 80%, 95%, 89% and 80%, respectively. The SND bioreactor achieved total nitrogen (TN) removal efficiencies of 33% and 79% for the SGBR effluent, when operated in down-flow mode without aeration and up-flow mode with aeration, respectively. The ufMMs, operated in dead-end filtration mode, were able to further reduce the COD and TSS by an average of 65% and 54%, respectively. The results for the PSW treatment system demonstrated the combined benefits of biological and physical treatment processes, with averaged COD, ortho-phosphate (PO43−-P), TSS and total dissolved solids (TDS) removal efficiencies of 91%, 51%, 97% and 52%, respectively, being achieved over 52 days. The final effluent was deemed suitable for discharge; although, the PO43- and NH4+-N requires further monitoring and the PSW treatment system design requires refinement.

Operation of a modified anaerobic baffled reactor coupled with a membrane bioreactor for the treatment of municipal wastewater in Taiwan

ABSTRACTA modified anaerobic baffled reactor (ABR) combined with a submerged membrane bioreactor (MBR) was applied to treat municipal wastewater. The performance of this process was examined in terms of the removal of organic matter, suspended solids, turbidity and nitrogen. The raw wastewater was fed to the 105 L ABR and then the treated effluent was driven to a 58 L MBR equipped with a submerged hollow fibre ultrafiltration membrane module. The integrated modified ABR–MBR process resulted in the complete removal of total suspended solids (TSS) and in very high chemical oxygen demand (COD) removal (93.3 ± 3.8%). Furthermore, the recycling of mixed liquor from the MBR to the modified ABR resulted in some denitrification occurring in the first compartment of the ABR, resulting in 53 ± 6% removal of nitrogen by the integrated process. The membrane flux was stable and above 20 L/m2h. Membrane examination at the nanoscale indicated the deposition of small particles on the surface of the membranes.

Performance of an outdoor membrane photobioreactor for resource recovery from anaerobically treated sewage

Abstract The objective of this work was to evaluate the performance of a pilot scale membrane photobioreactor (MPBR) for treating the effluent of an anaerobic membrane bioreactor (AnMBR) system. In particular, new experimental data on microalgae productivity, nutrient recovery, CO2 biofixation and energy recovery potential was obtained under different operating conditions, which would facilitate moving towards cost-effective microalgae cultivation on wastewater. To this aim, a 2.2-m3 MPBR equipped with two commercial-scale hollow-fibre ultrafiltration membrane modules was operated treating the nutrient-loaded effluent from an AnMBR for sewage treatment. The influence of several design, environmental and operating parameters on MPBR performance was studied. Among the conditions evaluated, variations in solar irradiance significantly affected the nutrient recovery rate (NRR). Operating at temperatures above 25 °C and high biomass concentrations, which increased light shading effect, negatively affected biomass production and NRR. Maximum biomass productivity of 66 mg VSS L−1 d−1 (areal productivity of 15.78 g VSS m−2 d−1) and NRR of 7.68 mg N L−1 d−1 and 1.17 mg P L−1 d−1 were achieved when operating at 4.5 days of biomass retention time. These results would outcome maximum theoretical energy recoveries and CO2 biofixations of about 0.43 kWh and 0.51 kg CO2 per m3 of treated water, respectively. Moreover, the excellent quality permeate that was produced (i.e. negligible levels of pathogens and suspended solids) represents a reclaimed water source.

Control systems for olive mill wastewater treatment with ultrafiltration and nanofiltration membrane in series based on the boundary flux theory.

Proper membrane process design can be a difficult task to accomplish when fouling is present, and must be faced. Engineers usually consider the project variables concerning productivity and selectivity and follow these targets. However, in the presence of fouling, additional parameters must be considered, implying better knowledge of fouling phenomena. One possible solution to increase the reliability of a process is the use of stable control systems. This article reports a suitable method to reach this target, based on the boundary flux theory. The knowledge of the boundary flux values permits avoidance of high fouling operating conditions on a selected membrane. The goal here was to determine the framework for control of an ultrafiltration (UF) and nanofiltration (NF) batch membranes-in-series process treatment for olive mill wastewater, relying on these boundary flux points, which will thereafter serve for the automatic control of the process by an advanced control system. In this work, boundary flux values equal to 10 L h-1 m-2 for the UF membrane module and 14.3 L h-1 m-2 for the NF one were estimated. Moreover, the membrane constant permeability loss, measured by integrating the sub-boundary fouling index, was estimated to be reduced in the order of 65.4% for the NF membrane after the applied pretreatment and UF. This strategy permitted attaining stable and constant productivity for both membranes. Moreover, it is shown that, relying on the boundary flux modelization, both types of control systems (feed control and pressure control) could be used reliably. The proposed approach could help safely narrow the overdesign of membrane processes due to fouling issues and thus would have an impact on the reduction of the costs for both membrane processes.

Performance and Mechanisms of Ultrafiltration Membrane Fouling Mitigation by Coupling Coagulation and Applied Electric Field in a Novel Electrocoagulation Membrane Reactor.

A novel electrocoagulation membrane reactor (ECMR) was developed, in which ultrafiltration (UF) membrane modules are placed between electrodes to improve effluent water quality and reduce membrane fouling. Experiments with feedwater containing clays (kaolinite) and natural organic matter (humic acid) revealed that the combined effect of coagulation and electric field mitigated membrane fouling in the ECMR, resulting in higher water flux than the conventional combination of electrocoagulation and UF in separate units (EC-UF). Higher current densities and weakly acidic pH in the EMCR favored faster generation of large flocs and effectively reduced membrane pore blocking. The hydraulic resistance of the formed cake layers on the membrane surface in ECMR was reduced due to an increase in cake layer porosity and polarity, induced by both coagulation and the applied electric field. The formation of a polarized cake layer was controlled by the applied current density and voltage, with cake layers formed under higher electric field strengths showing higher porosity and hydrophilicity. Compared to EC-UF, ECMR has a smaller footprint and could achieve significant energy savings due to improved fouling resistance and a more compact reactor design.

Performance of a pilot split-type anaerobic membrane bioreactor (AnMBR) treating antibiotics solvent wastewater at low temperatures

The performance of a new pilot split-type anaerobic membrane bioreactor (AnMBR) configuration for treating antibiotics solvent wastewater at low temperatures was evaluated in this study. The AnMBR system comprised an internal circulation (IC) and ultrafiltration membrane modules, working as the biological removal and physical retention, respectively. The whole process was divided into four stages in terms of the variation of temperatures (35±3°C, 25±3°C, 15±3°C, 25±3°C). Total chemical oxygen demand (CODtotal) and tetrahydrofuran (THFtotal) removal efficiency at temperatures as low as 15±3°C were similar to mesophilic conditions (35±3°C, 25±3°C), which achieved over 95% and 96%, respectively. While different mechanism of removal was obtained at different temperatures. The excellent removal efficiency was maintained via the combination of biological and physical removal, biological removal was the major reason of removal efficiency (>83.3%) at mesophilic temperatures and physical removal (>38.6%) dominated the effect at lower temperatures. As temperature decreased, permeate volatile fatty acids (VFA) in the bioreactor accumulated suggesting a reduction of methanogens activity and pH had a minimum value of 6.5. However, neither of them showed significant sign of water degradation towards the end of experiment. The examination of alkalinity, α value, and end-products of anaerobic fermentation, MLSS, MLVSS and MLVSS/MLSS suggested a negative effect slightly on microbial activity and no negative effect on the effluent quality at low temperatures due to the retention of membrane.

Effect of ultrafiltration membranes properties and channel configuration on membrane fouling and performance

The work describes the existing views on colloidal, suspended and organic fouling in ultrafiltration (UF) membrane modules using for natural water treatment. The paper presents the results of the experimental research allowing for a quantitative determination of sorption and plugging rates, and for evaluation of their effect on membrane performance loss over time. Small colloidal particles pose a risk to UF unit due pore plugging; especially when membranes treat water with a very low content of suspended solids. This effect often cannot be detected during short-time pilot tests, but it can have a decisive influence on the operation of a membrane unit. Study of the filterability characteristic of water contaminants enables us to forecast the filtration type on UF membranes and to evaluate their performance losses. The paper also describes the effect of a feed channel structure – in particular, a presence of a feed spacer in spiral wound membrane modules – on channel hydraulic resistance growth. The technique of channel resistance estimation, depending on suspended particles concentration in the source water, is presented.