Journal articles on the topic 'Membrance filters'
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1
Canalli Bortolassi, Ana Cláudia, Vádila Giovana Guerra, Mônica Lopes Aguiar, Laurence Soussan, David Cornu, Philippe Miele, and Mikhael Bechelany. "Composites Based on Nanoparticle and Pan Electrospun Nanofiber Membranes for Air Filtration and Bacterial Removal." Nanomaterials 9, no. 12 (December 6, 2019): 1740. http://dx.doi.org/10.3390/nano9121740.
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Often, solid matter is separated from particle-laden flow streams using electrospun filters due to their high specific surface area, good ability to capture aerial particulate matter, and low material costs. Moreover, electrospinning allows incorporating nanoparticles to improve the filter’s air filtration efficiency and bacterial removal. Therefore, a new, improved polyacrylonitrile (PAN) nanofibers membrane that could be used to remove air pollutants and also with antibacterial activity was developed. We engineered three different filters that are characterized by the different particles embedded in the PAN nanofibers: titanium dioxide (TiO2), zinc oxide (ZnO), and silver (Ag). Then, their filtration performance was assessed by quantifying the filtration of sodium chloride (NaCl) aerosol particles of 9 to 300 nm in diameter using a scanning mobility particle sizer. The TiO2_F filter displayed the smallest fiber diameter and the highest filtration efficiency (≈100%). Conversely, the Ag_F filter showed the highest quality factor (≈0.06 Pa−1) because of the lower air pressure drop. The resulting Ag_F nanofibers displayed a very good antibacterial activity using an Escherichia coli suspension (108 CFU/mL). Moreover, the quality factor of these membranes was higher than that of the commercially available nanofiber membrane for air filtration.
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Alayande, Abayomi Babatunde, Yesol Kang, Jaewon Jang, Hobin Jee, Yong-Gu Lee, In S. Kim, and Euntae Yang. "Antiviral Nanomaterials for Designing Mixed Matrix Membranes." Membranes 11, no. 7 (June 22, 2021): 458. http://dx.doi.org/10.3390/membranes11070458.
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Membranes are helpful tools to prevent airborne and waterborne pathogenic microorganisms, including viruses and bacteria. A membrane filter can physically separate pathogens from air or water. Moreover, incorporating antiviral and antibacterial nanoparticles into the matrix of membrane filters can render composite structures capable of killing pathogenic viruses and bacteria. Such membranes incorporated with antiviral and antibacterial nanoparticles have a great potential for being applied in various application scenarios. Therefore, in this perspective article, we attempt to explore the fundamental mechanisms and recent progress of designing antiviral membrane filters, challenges to be addressed, and outlook.
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Li, Xun Chao, and Cong Li. "The Development of Household Membrane Filters for Drinking Water Treatment." Applied Mechanics and Materials 535 (February 2014): 446–50. http://dx.doi.org/10.4028/www.scientific.net/amm.535.446.
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The health risks and potential environment damage from unsafe municipal water have greatly accelerated the development of household water filter around the world. Similarly, the emergence of membrane technology in recently decades has greatly stimulated the rapid development and wide applications of membrane filter. The most widely used types of household membrane filters currently include RO membrane filter, UF membrane filter and MF membrane filter. Such filters are commercially available and of broad prospects in spite of membrane fouling. This review looks back over previous developments and applications of such three household membrane filters for better evaluation of their future development.
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Shin, Woo-Jin, Hyung-Seon Shin, Ji-Hun Hwang, and Kwang-Sik Lee. "Effects of Filter-Membrane Materials on Concentrations of Trace Elements in Acidic Solutions." Water 12, no. 12 (December 12, 2020): 3497. http://dx.doi.org/10.3390/w12123497.
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Filtration is commonly used to separate liquids from solid materials before the determination of trace element concentrations in aqueous solutions. Therefore, it is important to determine how much elemental content is extracted from the filter itself or lost via absorption into the filter. In this study, we investigated three types of disposable syringe filters (polyvinylidene difluoride, PVDF; polytetrafluoroethylene, PTFE; PTFE with glass microfiber prefiltration media, GD/X) and their acid-cleaned versions using ammonium nitrate (NH4NO3) and acetic acid (HOAc) solutions. The concentrations of most trace elements (Li, Al, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Mo, Cd, Cs, Ba, Pb, and U) were higher in filtrates that had passed through acid-cleaned filters than those that had passed through uncleaned filters. In filtrates from PVDF and PTFE filters, many trace elements were below the detection limit. However, regardless of the filter type and acid cleaning, Li, Cu, Zn, Mo, and Ba concentrations in filtrates of NH4NO3 solutions, and Al, Cr, Mn, Cu, Zn, and Ba concentrations in filtrates of HOAc solutions were much higher than those of other trace elements. These differences were particularly noticeable in filtrates from GD/X filters containing glass microfiber layers. These data indicate that certain trace elements can be released from membrane materials by reacting with acid in the filtered solution. Furthermore, the amounts of each trace element were associated with the membrane type. These findings suggest that filter type should be carefully selected to obtain the required accuracy, in consideration of the target elements and whether an acid-cleaned filter is needed.
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Rodrigue, Lynda, and Marc C. Lavoie. "Comparison of different membranes for use in the colony-immunoblot technique." Canadian Journal of Microbiology 36, no. 3 (March 1, 1990): 231–35. http://dx.doi.org/10.1139/m90-040.
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We compared five different supports (Whatman paper filters Nos. 1, 5, and 40, nitrocellulose, and Nylon 66) for their suitability in the colony-immunoblot (CIB) technique. Results indicate that Whatman No. 5 filter paper recovered 94–98% of the bacterial colonies tested, were more resistant to tearing than the other Whatman papers tested, and showed reduced cross-reactions as compared with nitrocellulose membranes. Whatman No. 5 filters are 20 times less expensive than the nitrocellulose membranes usually used in the CIB technique. We thus adopted the former for our ecological studies of the murine oral cavity. Key words: colony-immunoblot, filter paper, nitrocellulose membrane, microbial ecology, oral cavity.
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Papageorgiou, Georgios T., Laura Mocé-Llivina, Christina G. Christodoulou, Francisco Lucena, Dina Akkelidou, Eleni Ioannou, and Juan Jofre. "A Simple Methodological Approach for Counting and Identifying Culturable Viruses Adsorbed to Cellulose Nitrate Membrane Filters." Applied and Environmental Microbiology 66, no. 1 (January 1, 2000): 194–98. http://dx.doi.org/10.1128/aem.66.1.194-198.2000.
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ABSTRACT We identified conditions under which Buffalo green monkey cells grew on the surfaces of cellulose nitrate membrane filters in such a way that they covered the entire surface of each filter and penetrated through the pores. When such conditions were used, poliovirus that had previously been adsorbed on the membranes infected the cells and replicated. A plaque assay method and a quantal method (most probable number of cytopathic units) were used to detect and count the viruses adsorbed on the membrane filters. Polioviruses in aqueous suspensions were then concentrated by adsorption to cellulose membrane filters and were subsequently counted without elution, a step which is necessary when the commonly used methods are employed. The pore size of the membrane filter, the sample contents, and the sample volume were optimized for tap water, seawater, and a 0.25 M glycine buffer solution. The numbers of viruses recovered under the optimized conditions were more than 50% greater than the numbers counted by the standard plaque assay. When ceftazidime was added to the assay medium in addition to the antibiotics which are typically used, the method could be used to study natural samples with low and intermediate levels of microbial pollution without decontamination of the samples. This methodological approach also allowed plaque hybridization either directly on cellulose nitrate membranes or on Hybond N+ membranes after the preparations were transferred.
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Schuerger, Andrew C., and William Hammer. "Use of Cross-Flow Membrane Filtration in a Recirculating Hydroponic System to Suppress Root Disease in Pepper Caused by Pythium myriotylum." Phytopathology® 99, no. 5 (May 2009): 597–607. http://dx.doi.org/10.1094/phyto-99-5-0597.
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Zoosporic pathogens in the genera Pythium and Phytophthora cause extensive root disease epiphytotics in recirculating hydroponic vegetable-production greenhouses. Zoospore cysts of Pythium myriotylum Drechsler were used to evaluate the effectiveness of cross-flow membrane filters to control pythiaceous pathogens in recirculating hydroponic systems. Four membrane filter brands (Honeycomb, Polypure, Polymate, and Absolife) were tested alone or in combination to determine which filters would effectively remove infective propagules of P. myriotylum from solutions and reduce disease incidence and severity. Zoospore cysts of P. myriotylum generally measured 8 to 10 μm, and it was hypothesized that filters with pore-sizes <5 μm would be effective at removing 100% of the infective propagules and protect pepper plants from root infection. Single-filter assays with Honeycomb and Polypure brands removed 85 to 95% of zoospore cysts when pore sizes were rated at 1, 5, 10, 20, or 30 μm. Single-filter assays of Polymate and Absolife brands were more effective, exhibiting apparently 100% removal of zoospore cysts from nutrient solutions on filters rated at 1 to 10 μm. However, plant bioassays with Honeycomb and Polymate single filters failed to give long-term protection of pepper plants. Double-filter assays with 1- and 0.5-μm Polymate filters significantly increased the protection of pepper plants grown in nutrient film technique systems but, eventually, root disease and plant wilt could be observed. Insect transmissions by shore flies were not factors in disease development. Scanning electron microscopy images of zoospore cysts entrapped on Polymate filters revealed zoospore cysts that were either fully encysted, partially encysted, or of unusually small size (3 μm in diameter). It was concluded that either the atypically small or pliable pleomorphic zoospore cysts were able to penetrate filter membranes that theoretically should have captured them.
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Zhang, Jinfeng, Guanyi Chen, Yanning Ma, Miao Xu, Songyan Qin, Xiaoliang Liu, Haijun Feng, and Lian Hou. "Purification of pickling wastewater from the steel industry using membrane filters: Performance and membrane fouling." Environmental Engineering Research 27, no. 1 (December 29, 2020): 200486–0. http://dx.doi.org/10.4491/eer.2020.486.
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A new technique for treating pickling wastewater discharged from the steel industry using membrane filters was developed and membrane fouling was characterized in a full scale membrane filter. The morphological and chemical properties were examined through scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma optical emission spectroscopy (ICP-OES) etc. The results showed that inorganic elements such as phosphates, chlorides, and sulfates were severely blocked in membrane surfaces and pores. The porosity, permeability, hydrophilic contact angle, and surface charge capacity of fouled membranes were all lower than those of new membranes, while the optimal neutralization reaction pH region for fouled membranes shifted and narrowed. Charge neutralization is a critical reason to membrane fouling. By increasing the Zeta potential of the pickling wastewater, the membrane fouling could be controlled. This method is proven to effectively improve the separation property of precipitates after pickling wastewater was neutralized. Moreover, Neutralization helped to reduce the unit number of treatment processes. This investigation could assist in obtaining a better understanding of the fouling properties and behavior in the full-scale membrane filters in the pickling wastewater treatment.
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Mänttäri, M., and M. Nyström. "Ultrafiltration and nanofiltration in the pulp and paper industry using cross-rotational (CR) filters." Water Science and Technology 50, no. 3 (August 1, 2004): 229–38. http://dx.doi.org/10.2166/wst.2004.0200.
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Ultra- and nanofiltration with high shear CR-filters have been utilized for cleaning of clear filtrates and effluents from the pulp and paper industry. The aim was to find out how different nanofiltration membranes operate at high shear conditions. The filtration efficiency of the membranes was evaluated by measuring flux, retention and fouling at various recovery and pH conditions. High fluxes (∼100 L/(m2h)) for nanofiltration membranes were measured when circulation waters from the paper machine were filtered at neutral conditions. In the filtration of discharge of external activated sludge treatment plants we measured fluxes around 150 L/(m2h) even at a concentration factor of 12. The best NF membranes removed over 80% of the organic carbon and of the conductivity and almost completely eliminated the color. With acidic waters fluxes and retentions were significantly lower. The NF270 membrane from Dow and the Desal-5 membranes from Osmonics had the highest flux and retention properties. However, the Desal-5 membrane lost its retention properties slowly, which restricts its use in the high shear CR-filter. CR-nanofiltration can be used in the pulp and paper industry without feed pre-treatment by ultrafiltration. This increases the attractiveness of high shear CR-nanofiltration.
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Wohlsen, T., J. Bates, B. Gray, and M. Katouli. "Evaluation of Five Membrane Filtration Methods for Recovery of Cryptosporidium and Giardia Isolates from Water Samples." Applied and Environmental Microbiology 70, no. 4 (April 2004): 2318–22. http://dx.doi.org/10.1128/aem.70.4.2318-2322.2004.
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ABSTRACT We evaluated the efficiency of five membrane filters for recovery of Cryptosporidium parvum oocysts and Giardia lamblia cysts. These filters included the Pall Life Sciences Envirochek (EC) standard filtration and Envirochek high-volume (EC-HV) membrane filters, the Millipore flatbed membrane filter, the Sartorius flatbed membrane filter (SMF), and the Filta-Max (FM) depth filter. Distilled and surface water samples were spiked with 10 oocysts and 10 cysts/liter. We also evaluated the recovery efficiency of the EC and EC-HV filters after a 5-s backwash postfiltration. The backwashing was not applied to the other filtration methods because of the design of the filters. Oocysts and cysts were visualized by using a fluorescent monoclonal antibody staining technique. For distilled water, the highest percent recovery for both the oocysts and cysts was obtained with the FM depth filter. However, when a 5-s backwash was applied, the EC-HV membrane filter (EC-HV-R) was superior to other filters for recovery of both oocysts (n = 53 ± 15.4 per 10 liters) and cysts (n = 59 ± 11.5 per 10 liters). This was followed by results of the FM depth filter (oocysts, 28.2 ± 8, P = 0.015; cysts, 49.8 ± 12.2, P = 0.4260), and SMF (oocysts, 16.2 ± 2.8, P = 0.0079; cysts, 35.2 ± 3, P = 0.0079). Similar results were obtained with surface water samples. Giardia cysts were recovered at higher rates than were Cryptosporidium oocysts with all five filters, regardless of backwashing. Although the time differences for completion of filtration process were not significantly different among the procedures, the EC-HV filtration with 5-s backwash was less labor demanding.
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Alonso-Echanove, Juan, Brian D. Sippy, Arthur E. Chin, Lisa Cairns, Rebecca Haley, Jay S. Epstein, Michael J. Richards, et al. "Nationwide Outbreak of Red Eye Syndrome Associated With Transfusion of Leukocyte-Reduced Red Blood Cell Units." Infection Control & Hospital Epidemiology 27, no. 11 (November 2006): 1146–52. http://dx.doi.org/10.1086/508817.
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Objective.To characterize red eye reactions occurring within 24 hours after receipt of units of leukocyte-reduced red blood cells, determine their etiology, and investigate their potential link to transfusion.Methods.We conducted a survey of transfusion facilities nationwide to determine the scope and magnitude of the reactions; performed case-control and cohort studies among transfused patients at the facility where most reactions occurred; and performed animal experiments, using cellulose acetate derivatives extracted from leukocyte-reduction filters and filter precursors, to reproduce reactions.Results.From January 1, 1997, through January 15, 1998, we identified 159 reactions in 117 patients from 17 states. Reactions were characterized by conjunctival erythema or hemorrhage (in 100% of patients), eye pain (in 62%), photophobia (in 46%), and decreased visual acuity (in 32%). Symptom onset occurred 1-24 hours after initiation of transfusion and resolved within a median of 5 days. Reactions were associated with transfusion sessions that included units of red blood cells filtered with a specific brand of filter, the LeukoNet filter (HemaSure) (odds ratio, 100.4;P< .001). There was a dose-response relationship between the number of LeukoNet-filtered units transfused and the attack rate for reactions, ranging from 0.8% among sessions in which 1 unit was transfused to 27.3% among sessions in which 3 or more units were transfused (P< .001). A similar ocular syndrome was elicited in rabbits injected with cellulose acetate derivatives extracted from unused LeukoNet filters or filter precursors. No reactions were reported after LeukoNet filters were withdrawn from the market.Conclusions.This transfusion-associated red eye syndrome was linked to a specific brand of leukocyte-reduction filter and likely resulted from cellulose acetate derivatives leached from the filter membrane.
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SPEEGLE, LESLIE, MICHAEL E. MILLER, STEFFEN BACKERT, and OMAR A. OYARZABAL. "Use of Cellulose Filters To Isolate Campylobacter spp. from Naturally Contaminated Retail Broiler Meat." Journal of Food Protection 72, no. 12 (December 1, 2009): 2592–96. http://dx.doi.org/10.4315/0362-028x-72.12.2592.
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Membrane filtration has been used to isolate Campylobacter spp. from feces, although ~5 log CFU/g must be present in the sample. Few studies have attempted to use filter membranes for the isolation of Campylobacter from foods. We investigated the minimum number of thermotolerant Campylobacter cells that pass through cellulose filters, the effect of different cell conditions on the rate of passage, and the minimum number of cells that could pass the filters from enriched broiler meat naturally contaminated with Campylobacter spp. Cellulose filters with 0.65-μm pore sizes retained fewer cells and were more effective than filters with 0.45-μm pore sizes. Scanning electron microscopy revealed that 15 min of contact of the filters with agar plates allowed for the passage of most bacteria. The minimum number of bacteria required to pass through the filters was contingent on cell conditions; nonmotile cells were retained more than motile cells (P < 0.05). The minimum number of motile bacteria from 24-h cultures and centrifuged cells were 2.2 and 2.1 log CFU, respectively, while the number of coccoid and nonmotile (flaA/B2 mutant) cells were 4.1 and 3.4 log CFU, respectively. Broiler meat samples enriched in Bolton's broth supplemented with 5% lysed blood showed that approximately 1.7 log CFU of Campylobacter can be filtered to pure colonies on agar plates. These results demonstrate that the motility of the bacteria influences passage through cellulose filters and that 0.65-μm-pore-size filters on agar plates help obtain pure Campylobacter colonies from enriched food samples.
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Katrivesis, Fotios K., Varvara Sygouni, Christakis A. Paraskeva, and Vagelis G. Papadakis. "A Performance Comparison of Pilot-Scale Sand Filtration and Membrane Filtration of Glafkos River Water." Journal of Marine Science and Engineering 9, no. 2 (February 16, 2021): 203. http://dx.doi.org/10.3390/jmse9020203.
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Surface-water treatment plants use the flocculation–precipitation method followed by gravity filters to remove suspended solids. In the present work, the replacement of gravity filters with ultrafiltration membrane units is suggested to improve the efficiency of water treatment and to reduce fixed and operational costs. A parametric pilot-scale study was conducted to compare the filtration efficiency of a deep bed and a membrane module for water-simulating river water of various turbidity degrees. Suspensions of kaolinite were prepared to simulate turbidity of the Glafkos River, Achaia Region of Greece and were filtered using a laboratory sand-bed column and a pilot ultrafiltration (UF) membrane unit. Operational parameters such as the particle concentration ratio, the flow rate, and the filter head loss were studied in the case of the granular bed. In the case of membrane filtration, the permeate flux, turbidity, and membrane permeability loss due to fouling were tested. A discussion in terms of the operational cost and environmental impacts was performed. Filtration capacity of the sand filter is a decreasing function of the flow rate and it was found less efficient than membrane ultrafiltration for increased turbidity or increased particle concentration values. Membrane ultrafiltration could achieve long-term economic profit while it is characterized by minimum environmental impact since the use of chemical reagents and the production of waste sludge are limited.
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Sanaei, P., G. W. Richardson, T. Witelski, and L. J. Cummings. "Flow and fouling in a pleated membrane filter." Journal of Fluid Mechanics 795 (April 13, 2016): 36–59. http://dx.doi.org/10.1017/jfm.2016.194.
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Pleated membrane filters are widely used in many applications, and offer significantly better surface area to volume ratios than equal-area unpleated membrane filters. However, their filtration characteristics are markedly inferior to those of equivalent unpleated membrane filters in dead-end filtration. While several hypotheses have been advanced for this, one possibility is that the flow field induced by the pleating leads to spatially non-uniform fouling of the filter, which in turn degrades performance. In this paper we investigate this hypothesis by developing a simplified model for the flow and fouling within a pleated membrane filter. Our model accounts for the pleated membrane geometry (which affects the flow), for porous support layers surrounding the membrane, and for two membrane fouling mechanisms: (i) adsorption of very small particles within membrane pores; and (ii) blocking of entire pores by large particles. We use asymptotic techniques based on the small pleat aspect ratio to solve the model, and we compare solutions to those for the closest-equivalent unpleated filter.
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Hui-Feng, Sun, Miwa Takamori, Noriko Hata, Issei Kasahara, and Shigeru Taguchi. "Application of Membrane Filters for Spectrophotometric Determination of Cationic Surfactants in River Water and Sediment." Journal of AOAC INTERNATIONAL 84, no. 6 (November 1, 2001): 1781–85. http://dx.doi.org/10.1093/jaoac/84.6.1781.
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Abstract Cationic surfactant (CS+) in urban river water and sediment was extracted and determined spectrophotometrically with 2 membrane filters. The CS+ in the water samples, mostly in the form of an ion associate with the coexisting anionic surfactant (AS−), was collected on a polytetrafluoroethylene (PTFE) membrane filter and eluted with methanol. Bromphenol blue (BPB), hydrochloric acid, and water were added to the methanol solution successively, and the mixed solution was filtered through a mixed cellulose ester membrane filter. The CS+-BPB− ion associate, formed by a counter ion exchange, was collected on the filter and dissolved into N,N-dimethylformamide (DMF) together with the mixed cellulose ester membrane filter. After addition of 2 drops of triethanolamine, the absorbance of the DMF solution was measured. The CS+ in sediment samples was extracted with methanol by ultrasonic irradiation; the methanol solution was then passed through a PTFE membrane filter and evaporated to dryness. The CS+ was redissolved in a small amount of methanol. For water samples, recoveries and relative standard deviations for 0.30 μM benzyldimethyltetradecylammonium ion, a standard material, were ≥93 and ≤5%, with a detection limit of 0.02 μM. Concentrations of CS+ in sediments were much higher than those in water samples, indicating that CS+ is adsorbed on the surface of the sediment.
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Wang, Han, Zuo Yi Yang, Jin Yong Liu, Gao Feng Zheng, and Ling Min Chen. "Explore on Pressure-Drop Performance of Nanofibrous Filtration Membrane." Advanced Materials Research 236-238 (May 2011): 1885–88. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.1885.
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High filtration efficiency of nanofibrous membrane has been proved in air filtration area, but, in addition to filtration efficiency, pressure drop is another important characteristic of fibrous filter. Because pressure-drop is related to energy wastage of filtration, it’s necessary to study. While there are not enough studies dedicated to pressure-drop of nanofibrous membrane filters. Here, different thickness PVA nanofibrous membranes were made by electrospinning, and they deposited on cotton scaffolds to form nanofibrous filter samples. Through testing these samples, we found as thickness of nanofibrous membrane increased, pressure-drop rose almost linearly, while filtration efficiency presented a different change trend. When thickness of nanofibrous membrane reaching a point, filtration efficiency attained extreme limit, even if increasing thickness nanofibrous membrane, filtration efficiency only rose limitedly, but pressure-drop still increased rapidly. At the same time, we found despite the thickness of nanofibrous membrane was thinner than conventional fibrous filter, pressure-drop of nanofibrous filter was obviously higher than conventional fibrous filter. So it’s remarkable phenomena. Through theoretical analysis and simulation, the causation of high pressure-drop of nanofibrous filter was discussed and provided. Decreasing diameter of fiber caused resistance performance change. It’s necessary to carry on a further research.
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Kaur, Satinderpal, Renuga Gopal, Wun Jern Ng, Seeram Ramakrishna, and Takeshi Matsuura. "Next-Generation Fibrous Media for Water Treatment." MRS Bulletin 33, no. 1 (January 2008): 21–26. http://dx.doi.org/10.1557/mrs2008.10.
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AbstractFibrous media in the form of nonwoven filters have been used extensively in water treatment as pre-filters or to support the medium that does the separation. Nonwoven media are composed of randomly oriented micron-size fibers and provide a one step separation as a substitute for conventional processes comprising chemical addition, flocculation, sedimentation, and sand filtration. At present the use of nonwoven filter media is limited to pre-filters and is not used further downstream as high performance filters. However it is expected that by reducing the fiber size in the nanometer range, higher filtration efficiency can be achieved. With the advent of nanotechnology, the ease of producing high quality nano scaled fibers is now a reality. Recent advancements in nanofibrous media through surface modifications have shown that nonwoven media can be used beyond the prefilter stage. Furthermore the pore size of the filter media can be controlled through modification of fiber size and thickness of membranes. These nanofibrous membranes possess high surface area and large porosity leading to high flux, low pressure membranes. This article highlights important opportunities and challenges associated with developing nanofibrous media for water treatment. In addition, we have attempted to capture a snapshot of this rapidly developing new area of fibrous media for water treatment for the benefit of the wider membrane community.
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Liu, Jing Xian, De Qiang Chang, Yue Xie, Ning Mao, and Xi Sun. "Research on Fine Particles Capture of Baghouse Filter Media." Applied Mechanics and Materials 300-301 (February 2013): 1293–97. http://dx.doi.org/10.4028/www.scientific.net/amm.300-301.1293.
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Industrial dust emission is one of the main sources of fine particle especially for PM2.5 in atmosphere. Filter media is the key component for baghouse. In the paper, several normal needle felt filters and membrane filter are studied through experiments. The performances of filter such as resistance, capture efficiency for total particle and number counting efficiency for fine particle are tested.The experimental results show that the resistance of filter increase after aging, the resisitance increasing rate of membrane filter is the smallest; The efficiencies for total particles of normal filter are above 99.9% at clean state, and 99.99% at stable state after aging; Although the filters have high efficiency for total particle, but the number counting efficiency for 10μm particle is 94%-99%, and 52%-92% for 2μm particles. New filters for fine particles are needed.
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Engström, J. E., and C. Leck. "Determination of water-insoluble light absorbing matter in rainwater using polycarbonate membrane filters and photometric detection." Atmospheric Measurement Techniques Discussions 2, no. 1 (February 4, 2009): 237–64. http://dx.doi.org/10.5194/amtd-2-237-2009.
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Abstract. A method for determination of water-insoluble light absorbing matter in rainwater has been developed. After collection the rainwater samples were filtered using polycarbonate membrane filter in the laboratory. After drying the filter in filtered air, the amount of water-insoluble light absorbing matter (soot) on the filters was determined with photometry at a wavelength of 555 nm. The precision for the method was better than 10% calculated as relative standard deviation. The overall loss of soot due to adsorption during collection and filtration was 22±2%. The detection limit was estimated to 0.025 in optical density, or 2 ng/ml expressed as a concentration assuming a filtration volume of 30 ml. Analysis of environmental samples have been successfully performed with the described method at the Maldives Climate Observatory Hanimaadhoo and Nepal Climate Observatory. At Maldives the average soot concentration in rain was 0.048 μg/ml and at the Nepal obseravtory 0.086 μg/ml.
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Hong, Chuanxue, Patricia A. Richardson, and Ping Kong. "Comparison of Membrane Filters as a Tool for Isolating Pythiaceous Species from Irrigation Water." Phytopathology® 92, no. 6 (June 2002): 610–16. http://dx.doi.org/10.1094/phyto.2002.92.6.610.
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Filter-based isolation is the primary approach for quantifying plant pathogens in irrigation water; however, the performance of various membranes is largely unknown. This study evaluated nine hydrophilic membranes for recovery of pythiaceous species, a group of very common and destructive pathogens on numerous ornamental plants and many agronomic crops. Three sources of water samples and three plating methods were used for the membrane comparison. Durapore5, Millipore5, and Osmonics5 filtered 100 ml of irrigation water or 50 ml of irrigation runoff in 10 s or less, whereas the other membranes required 34 s to 13.5 min or even a second membrane to filter the same water sample volume. Millipore5 and Durapore5 showed greater recovery rates than other membranes for all water sources when the membranes were directly inverted onto agar plates. Durapore5 was also one of the top two membranes for spore suspension and irrigation water samples when membrane washings were spread over the agar surface. Durapore5 was the only membrane that consistently performed well for both spore suspension and irrigation water samples. These data suggest that use of Durapore5 not only increases the sensitivity of filter-based isolation for quantifying pythiaceous species in irrigation water but also saves filtering time.
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Sauvegrain, P., A. Tazi-Pain, F. Rogalla, and F. Valter. "Anaerobic Biofiltration versus Aerobic Membrane Filtration: Comparison on a Difficult Substrate." Water Science and Technology 25, no. 10 (May 1, 1992): 211–18. http://dx.doi.org/10.2166/wst.1992.0249.
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Several methods were compared to treat heat treatment liquor on a municipal wastewater treatment plant, to reduce loading and allow upgrading. To ensure low suspended solids in the return flows, granular anaerobic filters were chosen in parallel with membrane treatment:–an upflow wood-based charcoal anaerobic filter–an upflow floating polystyrene anaerobic filter–an aerobic reactor (activated sludge) coupled with microfiltration. Very similar loading rates and removal efficiency was obtained with the anaerobic filters; they allow to treat highly concentrated effluents in a detention time of 10 h but COD removal efficiency was limited to 60%. The higher contact time of up to 7 days in aerobic treatment, coupled with microfiltration, achieves elimination of 85% of COD and 95% of BOD. Nevertheless, loading rates and biomass concentrations remained low and flux on the membranes was heavily restricted.
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Persaud, Dave, Mikhail Smirnov, Daniel Fong, and Pejman Sanaei. "Modeling of the Effects of Pleat Packing Density and Cartridge Geometry on the Performance of Pleated Membrane Filters." Fluids 6, no. 6 (June 5, 2021): 209. http://dx.doi.org/10.3390/fluids6060209.
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Pleated membrane filters are widely used to remove undesired impurities from a fluid in many applications. A filter membrane is sandwiched between porous support layers and then pleated and packed into an annular cylindrical cartridge with a central hollow duct for outflow. Although this arrangement offers a high surface filtration area to volume ratio, the filter performance is not as efficient as those of equivalent flat filters. In this paper, we use asymptotic methods to simplify the flow throughout the cartridge to systematically investigate how the number of pleats or pleat packing density affects the performance of the pleated membrane filters. The model is used to determine an optimal number of pleats in order to achieve a particular optimum filtration performance. Our findings show that only the “just right”—neither too few nor too many—number of pleats gives optimum performance in a pleated filter cartridge.
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Lyu, Chenxin, Peng Zhao, Jun Xie, Shuyuan Dong, Jiawei Liu, Chengchen Rao, and Jianzhong Fu. "Electrospinning of Nanofibrous Membrane and Its Applications in Air Filtration: A Review." Nanomaterials 11, no. 6 (June 6, 2021): 1501. http://dx.doi.org/10.3390/nano11061501.
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Air pollution caused by particulate matter and toxic gases is violating individual’s health and safety. Nanofibrous membrane, being a reliable filter medium for particulate matter, has been extensively studied and applied in the field of air purification. Among the different fabrication approaches of nanofibrous membrane, electrospinning is considered as the most favorable and effective due to its advantages of controllable process, high production efficiency, and low cost. The electrospun membranes, made of different materials and unique structures, exhibit good PM2.5 filtration performance and multi-functions, and are used as masks and filters against PM2.5. This review presents a brief overview of electrospinning techniques, different structures of electrospun nanofibrous membranes, unique characteristics and functions of the fabricated membranes, and summarization of the outdoor and indoor applications in PM filtration.
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Hüls, C. M., P. M. Grootes, and M.-J. Nadeau. "Ultrafiltration: Boon or Bane?" Radiocarbon 51, no. 2 (2009): 613–25. http://dx.doi.org/10.1017/s003382220005596x.
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Ultrafiltration of bone collagen, dissolved as gelatin (M ~100,000 D), has received considerable attention as a means to remove small contaminants and thus produce more reliable dates (Brown et al. 1988; Bronk Ramsey et al. 2004; Higham et al. 2006; Mellars 2006). However, comparative dating studies have raised the question whether this cleaning step itself may introduce contamination with carbon from the filters used (Bronk Ramsey et al. 2004; Brock et al. 2007; Hüls et al. 2007).Here, we present results of further ultrafiltration experiments with modern and fossil collagen samples using Vivaspin 20™ and Vivaspin 15R™ ultrafilters. Evidently, the Vivaspin 20 (VS 20) ultrafilter with a polyethersulfone (PES) membrane retains more material in the >30 kD fraction than the Vivaspin 15R (VS 15R) filter with a regenerated cellulose membrane (Hydrosat), which may be related to increased retention of proteins due to suboptimal electrostatic conditions during ultrafiltration with the PES membrane. In addition, this filter type shows clear evidence for contamination with fossil carbon, presumably from membrane fibers, in the <30 kD fraction. Radiocarbon measurements on ultrafiltrated fossil collagen seem to indicate small contributions of modern carbon via glycerin left on and within the filter membranes of both types. Although SEM pictures show film remnants on the fibrous filter structure of cleaned filter membranes, EDX analysis on the VS 20 membrane to not support the assumption this may be glycerin. Our observations indicate the risks and benefits of the use of ultrafiltration in cleaning collagen samples for 14C dating need to be further quantified, especially for the cleaning of fossil bone collagen of good quality samples.
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Li, Ting-Ting, Yujia Fan, Xixi Cen, Yi Wang, Bing-Chiuan Shiu, Hai-Tao Ren, Hao-Kai Peng, Qian Jiang, Ching-Wen Lou, and Jia-Horng Lin. "Polypropylene/Polyvinyl Alcohol/Metal-Organic Framework-Based Melt-Blown Electrospun Composite Membranes for Highly Efficient Filtration of PM2.5." Nanomaterials 10, no. 10 (October 14, 2020): 2025. http://dx.doi.org/10.3390/nano10102025.
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Particulate matter 2.5 (PM2.5) has become a public hazard to people’s lives and health. Traditional melt-blown membranes cannot filter dangerous particles due to their limited diameter, and ultra-fine electrospinning fibers are vulnerable to external forces. Therefore, creating highly efficient air filters by using an innovative technique and structure has become necessary. In this study, a combination of polypropylene (PP) melt-blown and polyvinyl alcohol (PVA)/zeolite imidazole frameworks-8 (ZIF-8) electrospinning technique is employed to construct a PP/PVA/ZIF-8 membrane with a hierarchical fibrous structure. The synergistic effect of hierarchical fibrous structure and ZIF-8 effectively captures PM2.5. The PP/PVA composite membrane loaded with 2.5% loading ZIF-8 has an average filtration efficacy reaching as high as 96.5% for PM2.5 and quality factor (Qf) of 0.099 Pa−1. The resultant membrane resists 33.34 N tensile strength and has a low pressure drop, excellent filtration efficiency, and mechanical strength. This work presents a facile preparation method that is suitable for mass production and the application of membranes to be used as air filters for highly efficient filtration of PM2.5.
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Shepherd, K. M., and A. P. Wyn-Jones. "Evaluation of different filtration techniques for the concentration of cryptosporidium oocysts from water." Water Science and Technology 31, no. 5-6 (March 1, 1995): 425–29. http://dx.doi.org/10.2166/wst.1995.0652.
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The relative performances of different filter matrices were assessed for the concentration of Cryptosporidium oocysts in water. Cartridge filtration methods were examined and compared with membrane filtration and a flocculation method using seeded tap and river water to determine the most efficient and consistent method of sample concentration. From 10L samples, calcium carbonate flocculation gave the most consistently high recovery rate of Cryptosporidium oocysts (tap water mean 72.9%; river water mean 41.9%), followed by membrane filtration using 1.2μm cellulose acetate membranes (tap water mean 37.8%; river water mean 26.6%). For filtration of larger volumes (>100L) of water the Cuno Microwynd II cartridge filter provided the highest recovery rate of oocysts (tap water mean 13.3%; river water mean 10.8%) when compared with the Vokes cartridge and Balston filters. All recoveries fell dramatically when sucrose flotation techniques were applied.
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Alabi, D. A., and A. A. Adesiyun. "Studies on microbial quality of filtered water in households of a university community in Nigeria." Journal of Hygiene 96, no. 2 (April 1986): 239–48. http://dx.doi.org/10.1017/s0022172400066018.
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SUMMARYWater samples from home filters in nine residential areas of a Nigerian university community were studied. The membrane filter technique was used to determine the total coliform and faecal coliform counts/100 ml of water. Most of the 100 samples studied were grossly contaminated with total coliform counts/100 ml ranging from 0–442, faecal coliform counts/100 ml, 0–216 and the total aerobic plate count per millilitre ranged from 3·0 × 103to 1·9 × 109c.f.u. The source (dams) of water, fitness of filter candles, frequency of cleaning candles and pH of water did not significantly (P> 0·05;X2) affect the microbial quality of either filtered boiled or unboiled tap water.Escherichia colitype I was isolated from 17·9% of the faccal coliforms tested but from only 2·3% of total coliforms.Enterobacter aerogeneswas most predominant (38·5%) amongst faecal coliforms isolated whileEnterobacter cloacaewas the most frequent (37·2%) of the total coliform isolates.The gross contamination of filltered water from all households sampled calls fpr am englightenment of residents on the proper use of home water filters.
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Sobsey, M. D., M. V. Yates, F.-C. Hsu, G. Lovelace, D. Battigelli, A. Margolin, S. D. Pillai, and N. Nwachuku. "Development and evaluation of methods to detect coliphages in large volumes of water." Water Science and Technology 50, no. 1 (July 1, 2004): 211–17. http://dx.doi.org/10.2166/wst.2004.0056.
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New and improved methods have been developed to detect somatic and male-specific coliphages in large volumes of water by single agar layer (SAL), enrichment and membrane filter methods. Somatic coliphages were detected efficiently on E. coli hosts C and CN13, male-specific coliphages were detected more efficiently on E. coli Famp than on Salmonella typhimurium WG49 and both types of coliphages were detected simultaneously on E. coli C3000. For water volumes of up to 100 ml, the SAL method was efficient and reliable. For water volumes of <1 L and as many as 10 multiple 1 L volumes, the enrichment method was efficient in detecting very low numbers of coliphages. Membrane filter methods, in which coliphages were adsorbed to and eluted from filters, also were relatively efficient, but they were less efficient than SAL and enrichment methods and were considered to be more cumbersome. For filter adsorption-elution methods, coliphage recoveries were most efficient for cellulose ester filters, less efficient for electropositive 1MDS filters and least efficient for a direct membrane filter method. Overall, the enrichment method was preferred because of its ability to easily and rapidly detect low levels of coliphages in large sample volumes by either presence-absence or most probable number quantification.
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Li, Ting-Ting, Xixi Cen, Hai-Tao Ren, Fei Sun, Qi Lin, Ching-Wen Lou, and Jia-Horng Lin. "One-Step Bark-Like Imitated Polypropylene (PP)/Polycarbonate (PC) Nanofibrous Meltblown Membrane for Efficient Particulate Matter Removal." Polymers 11, no. 8 (August 4, 2019): 1307. http://dx.doi.org/10.3390/polym11081307.
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A bark-like imitated polypr opylene (PP)/polycarbonate (PC) nanofibrous membrane was constructed by one-step meltblown technique for efficient particulate matter (PM) removal. The effects of PC content (0%, 1%, 3%, 5%, and 7%) on membrane thermal stability, microscopic characteristics, filtration performance, hydrophilicity, and water vapor transmission were investigated. The results demonstrated that using facile design of incompatibility and viscosity difference between PC and PP polymers decreases average fiber diameter, creating a bark-like groove appearance and increasing surface potential, making a new PP/PC membrane with high filtration performance. The resultant PP/PC membrane had finer average fiber diameter of 0.63 μm, which was nearly 89.41% lower than PP membranes (5.95 μm), and its quality factor (0.036 Pa−1) was nearly 2.12 times than that of PP membranes (0.017 Pa−1) with the die hole diameter of 0.5 mm. This fabrication technique of a special meltblown filter membrane saves the cost of die retrofitting and post-processing, which provides an innovative method for particulate efficient removal of high efficient filters.
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Murray, Anna, Mario Goeb, Barbara Stewart, Catherine Hopper, Jamin Peck, Carolyn Meub, Ayse Asatekin, and Daniele Lantagne. "Fouling in hollow fiber membrane microfilters used for household water treatment." Journal of Water, Sanitation and Hygiene for Development 5, no. 2 (April 30, 2015): 220–28. http://dx.doi.org/10.2166/washdev.2015.206.
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The Sawyer PointOne hollow fiber membrane microfilter is promoted for household water treatment in developing countries. Critical limitations of membrane filtration are reversible and irreversible membrane fouling, managed by backwashing and chemical cleaning, respectively. The PointOne advertised lifespan is 10 years; users are instructed to backwash as maintenance. Owing to reduced turbidity and bacterial removal efficiencies, six PointOnes were removed from Honduran homes after 23 months of use. In the laboratory, we tested sterile water filtrate for turbidity and bacterial presence before and after backwashing and chemical cleaning. Sterile water filtrate from uncleaned filters had turbidity of 144–200 NTU and bacteria counts of 13–200 CFU. Cleaned filter effluent was positive for total coliforms. On one new and one used, cleaned filter, we imaged membranes with scanning electron microscopy and characterized surface elemental compositions with spectroscopy. Images and spectroscopy of the used, cleaned membrane revealed a dense, cake fouling layer consisting of inorganic metal oxides, organic material, and biofouling. Burst fibers were visually observed. This PointOne was thus irreversibly fouled and non-functional after <2 years of use. Further research is recommended to determine: impacts of source water quality on PointOne performance, a cleaning regimen to manage fouling, and an appropriate filter lifespan.
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Wojcicki, J., W. Piatkiewicz, A. Werynski, J. Waniewski, H. Goch, and M. Hay. "Membrane Plasma Fractionation: Effect of the Surface Area." International Journal of Artificial Organs 11, no. 5 (September 1988): 387–92. http://dx.doi.org/10.1177/039139888801100514.
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The influence of the surface area on the performance of plasma filters for dead-end mode of filtration is presented in this paper. Theoretical analysis of the dead-end filtration was performed and verified experimentally (using ENKA cellulose-diacetate PF-100 membranes) in respect to β-lipoprotein. The theoretical model allows to optimize the course of the transmembrane pressure during plasma fractionation procedure in dependence of the surface area, initial concentration of macromolecules, total volume of the feed and membrane structure. The results indicate that the surface area effect is an important factor in the operation of membrane plasma fractionation and should be considered in the design of the plasma fractionation filter.
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Zhang, Yu Long, and Tao Dong. "A Membrane-Based Sample Preparation Kit for Waterborne Pathogens: Design and Manufacture." Applied Mechanics and Materials 281 (January 2013): 75–79. http://dx.doi.org/10.4028/www.scientific.net/amm.281.75.
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Membrane-based microfluidic devices have been demonstrated in recent literature to show a significant potential in developing low-cost but high-efficient analytical devices. Usually, the step of sampling and sample preparation is the most importance processes in the whole analytical experiments. This study designed and manufactured a low-cost kit for water sampling and sample preparation of waterborne pathogens, especially protozoan parasites. Subsequently, Saccharomyces cerevisiae was employed as the model microbe to verify the function of kit. The concepts of green design and agile manufacturing were reflected throughout this work. In the devices, membrane filters were fixed and locked in a pair of disposable filter holders, and then the filter set would be assembled with a volumetric sample container to filter the microorganism in water samples. After the sampling process, the used filter holder with microbes on the membrane would be taken out and conserved in a preservation buffer, which could protect the DNA/RNA molecules inside the cells. When these filter holders were transported to a remote laboratory, the sample preparation cassette will be used in the on-site extraction of the DNA/RNA from the cells on the membrane. At last, the eluate was made for further identification, i.e. NASBA tests. Eight kinds of candidate membrane filters were evaluated in the kit, and the function of the kit was verified.
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Kelly, Wayne, Donald Grant, and Joseph Zahka. "Optimization of Filter Properties for Recirculating Etch Baths." Journal of the IEST 43, no. 3 (June 14, 2000): 30–40. http://dx.doi.org/10.17764/jiet.43.3.72574h1883p177u4.
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Membrane filters are often used to remove small particles from liquids in recirculating etch baths (REBs). The ideal filter for this application would have both high particle capture efficiency and high flow permeability. Unfortunately, filters with high particle capture efficiency often have low permeability because the dominant particle capture mechanism is mechanical sieving. This paper describes more efficient capture mechanisms, interception and diffusion, and a filter with a surface modified to capture particles by these mechanisms. The filter has the same permeability as a conventional 0.45-μm filter and retains particles more efficiently than a conventional 0.05-μm filter. The filter is capable of removing multiple types of small (0.065-μm) particles (polystyrene latex, silicon nitride, alumina, etc.) with high efficiency (> 99.9 percent).
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Ensink, Jeroen H. J., Andy Bastable, and Sandy Cairncross. "Assessment of a membrane drinking water filter in an emergency setting." Journal of Water and Health 13, no. 2 (October 11, 2014): 362–70. http://dx.doi.org/10.2166/wh.2014.025.
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The performance and acceptability of the NeroxTM membrane drinking water filter were evaluated among an internally displaced population in Pakistan. The membrane filter and a control ceramic candle filter were distributed to over 3,000 households. Following a 6-month period, 230 households were visited and filter performance and use were assessed. Only 6% of the visited households still had a functioning filter, and the removal performance ranged from 80 to 93%. High turbidity in source water (irrigation canals), together with high temperatures and large family size were likely to have contributed to poor performance and uptake of the filters.
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Górka, Andrzej. "Model of a filtration process using a membrane filter with uniform transmission structure." Bulletin of the Military University of Technology 66, no. 3 (September 30, 2017): 133–53. http://dx.doi.org/10.5604/01.3001.0010.5397.
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The paper presents a model of a microfiltration filter for separation of biological microparticles from body fluids, including peripheral blood. The model used a single membrane filter with a homogeneous 2D transmission structure. In the model, the individual sieve with a uniform transmission structure in 2D space was applied. Because of the required survival of biological particles, the presented model was limited to the narrow filtration conditions that guarantee biological activity of these particles. In this model, the filtration process proceeds in the gravitational field without the involvement of external forces forcing or inhibiting the filtration process. Based on this model there were given basic dependencies describing the required filtration process conditions, such as filtration time and internal forces for particle migration in the filtered body fluid. The basic relationships between the height of the filtered column, duration of the process, and average fluid expenditure of the filtration process for different shapes of the channels molecular drainage lines filter have been determined. Based on this data, the directions of further works on improving the presented model of molecular filtration of biological particles for enriching selected biological fractions have been described. Keywords: micro filtration, filter sieves, filter membranes, filtration of biological particles, filtration membranes
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Werner, Roman Alejandro, Dominik Ulrich Geier, and Thomas Becker. "The Challenge of Cleaning Woven Filter Cloth in the Beverage Industry—Wash Jets as an Appropriate Solution." Food Engineering Reviews 12, no. 4 (July 24, 2020): 520–45. http://dx.doi.org/10.1007/s12393-020-09228-x.
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Abstract Beverage production requires many different and complex unit operations. One crucial procedural step is filtration. Typical filters are filter presses, candle filters, membrane filters, belt filters, and drum filters, which require considerable hygienic precaution and the application of appropriate cleaning concepts. In the last decades, the hygienic design has become a central design feature of equipment in the beverage and food industries. Today, also correspondent concepts regarding filter cloth increasingly come to the fore. However, filter cloth cleaning is rapidly facing limitations. Complex filter geometries originating from different gauzes and sensitive polymeric materials hinder efficient cleaning. Additionally, extensive biological residues adhering to the filter surface increase the challenge of cleaning. The goal of this paper is to outline the cleaning of woven filter cloths systematically with a particular focus on beverages and correspondent biophysical interactions between filter and residue. Based on these elemental cleaning limits of filter cloths, this paper focuses mainly on jet cleaning as one of the most appropriate cleaning methods. The flow-mechanical properties are discussed in detail since these are precisely the parameters that, on the one hand, describe the understanding of the cleaning process and, on the other hand, show how a wash jet can be adjusted precisely. In contrast to conventional cleaning techniques, such wash jets are expeditious to adapt and offer the best prerequisites to enable demand-oriented and optimized cleaning concepts. The latest research and approaches are enhancing jet efficiency and highlight their potentials for future process strategies.
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Lee, Jae-Keun, Benjamin Liu, and Kenneth Rubow. "Latex Sphere Retention by Microporous Membranes in Liquid Filtration." Journal of the IEST 36, no. 1 (January 1, 1993): 26–36. http://dx.doi.org/10.17764/jiet.2.36.1.3013036291k8n475.
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An experimental study of particulate matter retention by microporous membranes during liquid filtration has been conducted using 0.1, 0.22, 0.45, and 0.65-μm-rated hydrophilic and hydrophobic membrane filters. Retention measurements have been made with polystyrene latex spheres using an automated filter test system and a laser particle counter to measure the upstream and downstream particle concentration. Particle filtration during loading tests was found to begin with a sieving dominant regime followed by a transition regime and a cake filtration regime as particles accumulate inside the filter pores and on the filter surface. For latex sphere sizes equal to the nominal pore size of the filter, the initial filter efficiencies ranged from 97 to 99.9 percent. Complete retention (>99.9999999 percent) was achieved for a range of particle sizes two to three times the rated pore sizes of the filter. With the addition of a surfactant to the liquid, the retention was found to be lowered as a result of enhanced particle passage through the filter due to modified surface adsorption and steric stabilization. It was found that particle retention by sieving with the addition of surfactant provided the "worst-case" test for filter performance.
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Ahluwalia, R. K., and H. K. Geyer. "Fluid Mechanics of Membrane-Coated Ceramic Filters." Journal of Engineering for Gas Turbines and Power 118, no. 3 (July 1, 1996): 526–33. http://dx.doi.org/10.1115/1.2816679.
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Analytical models are formulated for evaluating the fluid mechanics of membrane-coated, dead-end ceramic filters. The models are applicable to forward flow as in the filtration mode and reverse flow as in the back-pulse cleaning mode. General criteria are derived to size the filter passages from considerations of Darcy pressure drop, friction pressure drop, and the dynamic head. These criteria together with Reynolds numbers are shown to provide measures of nonuniformities in face velocity and pressure that develop in the filter passages for atmospheric and high-pressure applications. A methodology is presented for optimizing the venturi geometry from the standpoint of minimizing pulse gas usage and controlling the thermal load imposed on the filter assembly.
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Grant, Donald, Travis Lemke, Greg Duepner, Donna Wilkes, and Norm Powell. "Measurement of Inorganic Contaminant Extraction from Fluid Handling Components By Dynamic Extraction." Journal of the IEST 39, no. 2 (March 31, 1996): 29–37. http://dx.doi.org/10.17764/jiet.2.39.2.37v188215vww31lx.
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This paper addresses extraction of inorganic contamination from fluid handling components into semiconductor process chemicals. It presents a method of dynamic extraction that measures the rate at which inorganic contaminants are extracted from components as a function of time. The method overcomes many of the shortcomings of conventional techniques. It allows prediction of the amount of contamination added to chemical in a process tool with time. Examples of its use to measure extraction from all-Teflon 0.05-μm microporous membrane filters in 49 percent HF are included. Extraction from five different types of filters was measured. Each filter was tested for 2 to 8 weeks with multiple samples taken during the course of the extraction for metal analysis. Filters of the same type had similar extraction rates and similar contaminant "fingerprints." There were large differences between filter types. The use of an inappropriate O-ring on a filter cartridge was identified. The decrease in the rate of extraction from the filters was similar to theoretical predictions.
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Ahmad, Norhayati, Nakamura Yuzo, Hiroki Kamibayasi, and Maisarah Mohamed Bazin. "Study on Fabrication of Ceramic Membrane from Shirasu Balloon for Waste Water Filtration." Advanced Materials Research 686 (April 2013): 305–10. http://dx.doi.org/10.4028/www.scientific.net/amr.686.305.
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The fabrication of low cost ceramic membranes for microfiltration were studied by using a natural materials (shirasu balloon) which are produced from glassy volcanic materials. The shirasu powder was formed into cylindrical shaped membranes and sintered at five different temperatures from 600 °C to 800 °C using spark plasma sintering (SPS). The porosity and density of membranes were measured according to Archimedes method. The effect of sintering temperatures on microstructure and phase of the membranes has been investigated using FESEM and XRD. A filtration experiment was carried out to study the membrane performance for waste water filtration. The quality of the filtered water was determined by analyse the pH, turbidity, suspended solid, chemical oxygen demand (COD) and biochemical oxygen demand (BOD5). The porosity reduced from 48.9% to 40.32% while the membrane density increased from 1.15 g/cm3 to 1.33 g/cm3 with increasing sintering temperatures from 600 °C to 800 °C. A little shrinkage occur during spark plasma sintering process. From the FESEM microstrcture, the maximum pore size of the membrane that has been observed at 600 °C is about 4.7 µm. Shirasu membrane are able to produce clean and clear treated water during the microfiltration test with membrane sintered at 800 °C and there is an improvement in quality of water that has been filtered. The ceramic water filter was successfully produced without the involvement of the high-tech, sophisticated machines and methods as well as complex materials
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Yang, Kui, Hui Lin, Shangtao Liang, Ruzhen Xie, Sihao Lv, Junfeng Niu, Jie Chen, and Yongyou Hu. "A reactive electrochemical filter system with an excellent penetration flux porous Ti/SnO2–Sb filter for efficient contaminant removal from water." RSC Advances 8, no. 25 (2018): 13933–44. http://dx.doi.org/10.1039/c8ra00603b.
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Liu, Jing Xian, De Qiang Chang, Li Ting Miao, Ning Mao, and Xi Sun. "Experiment Investigation on Two Filter Medias for Air Filtration." Applied Mechanics and Materials 300-301 (February 2013): 1340–43. http://dx.doi.org/10.4028/www.scientific.net/amm.300-301.1340.
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As the fast development of industry, clean air quality environment are needed in more manufactory fields. Filter media is the key material for high efficiency filtration. In this paper, glass fiber filter and PTFE membrane filter are studied with filtration test. The results show that glass fiber filter has low porosity, lead to lower penetration and higher resistance than PTFE filter. Penetration of filters decrease with mass load increasing and face velocity decreasing. Resistance increase with mass loading and face velocity increasing.
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Lawal, Nurudeen Samuel, Kolawole Ogedengbe, Olukayode Omotayo Smith Ojo, and Abubakre Adeyanju Odufowokan. "Assessment of a submerged membrane bioreactor with composite ceramic filters for cassava wastewater treatment." Research in Agricultural Engineering 66, No. 2 (June 29, 2020): 72–79. http://dx.doi.org/10.17221/109/2018-rae.
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Cassava processing activity is characterised by the generation of an enormous quantity of toxic wastewater with detrimental effects on the environment if disposed of without adequate treatment. To alleviate this concern, lab-scaled cylindrical-shaped composite ceramic filters produced from rice husk and clay mixed with equal proportions of activated carbon, kaolin and sherd powder were produced and assessed in a membrane bioreactor. The permeate obtained from the filter with 2.39% rice husks, 0.95% activated carbon, 0.80% kaolin, 0.40% sherd powder and 95.47% clay gave the optimum pollutant removal efficiency. The average removal efficiencies of the chemical oxygen demand (COD), biochemical oxygen demand (BOD), turbidity and hydrogen cyanide (HCN) were 98.32, 78.93, 37.81 and 56.52%, respectively. The pH increased from 3.8 to a maximum value of 6.5. The flux ranges from 0.005 [m<sup>3</sup>·(m<sup>2</sup>·d<sup>–1</sup>)] to a maximum value of 0.108 [m<sup>3</sup>·(m<sup>2</sup>·d<sup>–1</sup>)] obtained for the filter with 1.45% rice husks. The availability of low-cost construction materials and the ease of operation makes the concept a promising option for treating cassava wastewater, however, an optimisation study is required to improve the filter performance and enhance the field applications.
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Lloyd, G., J. Howells, C. Liddle, and P. L. Klineberg. "Barriers to Hepatitis C Transmission within Breathing Systems: Efficacy of a Pleated Hydrophobic Filter." Anaesthesia and Intensive Care 25, no. 3 (June 1997): 235–38. http://dx.doi.org/10.1177/0310057x9702500304.
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It has been suggested that breathing circuits contaminated with body fluids may provide a route of nosocomial patient-to-patient transmission of the hepatitis C virus. Thus, a number of authorities have recommended the use of breathing circuit filters to minimize such risks. The present study sought to simulate a humidified breathing circuit and evaluate two different designs of breathing circuit filters to determine their efficacy in preventing passage of the hepatitis C virus. A hydrophobic pleated-membrane filter consistently prevented the passage of hepatitis C virus while a large-pore “electret” filter design was ineffective. We conclude that not all filter types are equally suited to preventing the passage of viruses and we therefore consider it essential that, if filters are intended to prevent the passage of named pathogens in a humidified breathing circuit, they should be evaluated in a similar experimental system to that described in order to prove their efficacy.
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Kopylova, Natalia, Alexei Kopylov, and Yuri Salomatov. "Results of experimental studies and numerical modeling of multistage waveguide-slotted membranes filters with complex slots geometry." MATEC Web of Conferences 158 (2018): 01018. http://dx.doi.org/10.1051/matecconf/201815801018.
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The article contains the results of an experimental study and numerical simulation of the amplitude-frequency characteristics of one, three and four-stage filters on waveguide-slotted membranes with complex resonance slot geometry membranes located in a rectangular 35x15 mm waveguide. The design of filters and the topology of a complex slot in the membrane are shown. The results can be useful in the design of waveguide filters in the frequency range 5.5 … 8.5 GHz.
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Brügger, A., K. Voßenkaul, T. Melin, R. Rautenbach, B. Golloing, U. Jacobs, and P. Ohlenforst. "Reuse of filter backwash water by implementing ultrafiltration technology." Water Supply 1, no. 5-6 (June 1, 2001): 207–14. http://dx.doi.org/10.2166/ws.2001.0116.
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Membrane filtration allows safe retention of microorganisms when treating filter backwash water from conventional drinking water filters. The permeate of the membrane plant can thus be reused to produce drinking water. The benefits are a higher yield of the drinking water treatment plant and a minimised wastewater production. This paper discusses the results of a pilot study, cost data and full-scale operation experiences concerning the application of ultrafiltration to treat filter backwash water. The effectiveness of ultrafiltration was assessed with regard to flux, cost and permeate quality.
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De Giglio, Osvalda, Giusy Diella, Paolo Trerotoli, Michela Consonni, Roberta Palermo, Marina Tesauro, Pasqualina Laganà, Gabriella Serio, and Maria Teresa Montagna. "Legionella Detection in Water Networks as per ISO 11731:2017: Can Different Filter Pore Sizes and Direct Placement on Culture Media Influence Laboratory Results?" International Journal of Environmental Research and Public Health 17, no. 6 (March 20, 2020): 2077. http://dx.doi.org/10.3390/ijerph17062077.
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Determination of Legionella concentrations in water networks is useful for predicting legionellosis risks. The standard culture technique using concentration with membranes filters is the most commonly used method for environmental surveillance of Legionella. The aim of this study was to verify whether filtration with different filter pore sizes (0.2 and 0.45 µm) according to (ISO) 11731:2017, followed by directly placing them on culture media, can influence Legionella detection. Three laboratories participated in an experimental study that tested a known suspension of Legionella pneumophila (Lpn) serogroup 1 (ATCC 33152) (approximate final cell density of 15 CFU/mL). E. coli (ATCC 11775) and Pseudomonas aeruginosa (ATCC 25668) were included as control tests. The average (95% CI) percentage of recovery of Lpn was 65% using 0.45-µm filters and 15% using 0.2-µm filters (p < 0.0001). For control tests, the average (95% CI) percentage of recovery was higher with 0.45 vs. 0.2 µm filters: 97% vs. 64% for Escherichia coli (p < 0.00001) and 105% vs. 97% (p = 0.0244) for P. aeruginosa. Our results showed that the 0.45-µm filters provided the greatest detection of Legionella. Because the current national guidelines leave the choice of membrane porosity to the operator, experimental studies are important for directing operators towards a conscious choice to standardize Legionella environmental surveillance methods.
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Wakita, Masahiro, and Kenji Suzuki. "Ceramic Membrane Filter." MEMBRANE 34, no. 1 (2009): 52–55. http://dx.doi.org/10.5360/membrane.34.52.
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Murray, Anna L., Barbara Stewart, Catherine Hopper, Ellen Tobin, Jimmy Rivera, Henry Mut-Tracy, Patrick Stewart, et al. "Laboratory efficacy and field effectiveness of hollow fiber membrane microfilters used for household water treatment in Honduras." Journal of Water, Sanitation and Hygiene for Development 7, no. 1 (February 6, 2017): 74–84. http://dx.doi.org/10.2166/washdev.2017.156.
Full textAbstract:
The Sawyer PointONE™ hollow fiber membrane filter is increasingly promoted for long-term household water treatment in developing countries. Limited data demonstrate PointONE™ microbiological laboratory efficacy and short-term diarrheal disease reduction among users, but household microbiological data is lacking. To compare laboratory and household PointONE™ filter microbiological performance, we enumerated Escherichia coli (E. coli) and total coliforms in source and filtrate water from: (1) one new filter with E. coli-spiked water (107–109 CFU/100 mL) in the laboratory, (2) one new filter with natural Maine and Honduran surface waters, and (3) 50 filters used in Honduran homes for 1–3 years. In laboratory tests, all filtrate samples had <1 CFU/100 mL E. coli (>99.99999% reduction). In natural surface waters, all filtrate samples had ≤1 MPN/100 mL E. coli (≥99.5% reduction). In households, filtrate samples had geometric mean 5.1 MPN/100 mL E. coli (90% reduction), with only 30% of filtrate samples complying with international standards of undetectable E. coli. Total coliform presence in natural water filtrate varied for both new and household filters. The discrepancy between laboratory and household results and premature filter failure are not well understood. Further research is recommended to understand this performance disparity and determine filter failure mechanisms in households.
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Thompson, M. A. "Membrane filtration of high turbidity sources." Water Supply 1, no. 5-6 (June 1, 2001): 325–30. http://dx.doi.org/10.2166/ws.2001.0129.
Full textAbstract:
Membrane filtration processes have become widely used for low turbidity water sources that require particle removal and disinfection. In cases where the feed water contains high turbidity levels or high fouling tendencies, pre-treatment has been required to allow the membranes to operate efficiently. Submersion membranes have allowed direct treatment on many of these water supplies but operate under vacuum. This presents limitations on operating flux and design conditions for incorporating into existing facilities. The treatment unit designs are also very expensive to implement for small water treatment applications. A recently developed pressure driven ultrafiltration (UF) membrane is being tested on several different water sources and has demonstrated exceptional operation on high turbidity feed water sources. The module design includes a single potted end with the membrane fibers looped on the bottom to allow draining of solids from the module. The UF membrane filters outside to inside and has been operated on feed water turbidity levels up to 200 ntu. The availability of a pressure driven hollow fiber membrane that can efficiently filter high suspended solids water sources can provide a cost effective solution for many small to medium sized water supplies. Conditioning the feed water with a coagulant or direct filtration of high turbidity feed water can be used depending on the organic material present without settling or other clarification process. This eliminates the need for additional structural pretreatment and reduces overall system cost and size. Current limitations include the module size that makes this cost prohibitive for very large systems. Larger membrane systems where high-suspended solids are present in the feed water have been utilizing immersion membrane technologies more and more over the past few years. These systems typically operate under a vacuum and can be used for large water treatment plants as their design allows large filtration modules such as Memcor's CMFS filter block at 880 m3/hr. This allows significant capital cost reductions and allows membrane filtration to be competitive to conventional filtration technologies for virtually all filtration applications. This paper will review the economics and performance of both pressure driven and immersion membrane systems for small to large water supply systems on feed water containing high-suspended solid levels. Actual testing data for the new pressure driven hollow fiber UF membrane and immersion membrane systems will be provided on different water supplies including unconditioned surface water, filter backwash water and coagulated surface water.