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1
Jugade, Sanket S., Anuj Aggarwal e Akshay K. Naik. "Nanomechanical spectroscopy of ultrathin silicon nitride suspended membranes". European Physical Journal Applied Physics 94, n. 2 (maggio 2021): 20301. http://dx.doi.org/10.1051/epjap/2021210068.
Testo completoAbstract (sommario):
Mechanical properties of a nanomechanical resonator significantly impact the performance of a resonant Nano-electromechanical system (NEMS) device. We study the mechanical properties of suspended membranes fabricated out of low-pressure chemical vapor deposited silicon nitride thin films. We fabricated doubly-clamped membranes of silicon nitride with thickness less than 50 nm and length varying from 5 to 60 μm. The elastic modulus and stress in the suspended membranes were measured using Atomic Force Microscope (AFM)-based nanomechanical spectroscopy. The elastic moduli of the suspended membranes are significantly higher than those of corresponding on-substrate thin films. We observed a reduction in net stress after the fabrication of suspended membrane, which is explained by estimating the thermal stress and intrinsic stress. We also use a mathematical model to study the stress and thickness-dependent elastic modulus of the ultrathin membranes. Lastly, we study the capillary force-gradient between the SiNx suspended membrane-Si substrate that could collapse the suspended membrane.
2
Mahmud, Mahmud, Muthia Elma, Rahmat Subkhan, Aulia Rahma, Rhafiq Abdul Ghani, Rendy Muhamad Iqbal e Mohd Hafiz Dzarfan Othman. "Comparison of Hollow Fiber and Flat Sheet Membranes for Removing TDS and Turbidity of Palm Oil Mill Effluent Wastewater". Diffusion Foundations and Materials Applications 36 (6 novembre 2024): 15–26. http://dx.doi.org/10.4028/p-5wccge.
Testo completoAbstract (sommario):
The most significant pollutant produced from agricultural industry in Kalimantan, Indonesia is Palm Oil Mill Effluent (POME). Due to the high levels of suspended particles and organic matter, POME has become a brownish color with high turbidity, color, chemical oxygen demand, and oil and grease content. To recycle the POME wastewater as clean water, these pollutants must be eliminated. In this study, we compare the effectiveness of hollow fiber (HF) and flat sheet (FS) membrane to remove total dissolved solid (TDS) and turbidity from POME with varied filtration pressure. HF and FS membrane were prepared from PVDF and nylon66 polymer, respectively. The PVDF HF membrane was modified using TiO2 and SBE (spent bleaching earth) to improve HF membrane properties to maintaining fouling. Meanwhile, FS membrane was added by pectin to increase the hydrophilic properties. Overall membrane’s morphology was determined by Scanning Electron Microscopy (SEM) to investigate the membrane structure. Both of HF and FS membrane were operated via ultrafiltration (UF) under cross flow system. The filtration pressures were varied at 1-3 bar and followed by flux and rejection evaluation. The results show both HF and FS membranes has stability flux. In addition, TDS rejection up to 25% while turbidity is excellent high over 95% for all membranes. The fabrication HF membrane has finger like-sponge structure and FS membrane exhibits sponge asymmetric structure. Overall, all membranes perform highest water flux (FS membrane) while highest rejection conducted by HF membrane for POME wastewater treatment.
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Makisha, Nikolay A. "Research of performance characteristics of membrane modules for wastewater treatment". Stroitel stvo nauka i obrazovanie [Construction Science and Education], n. 1 (31 marzo 2020): 6. http://dx.doi.org/10.22227/2305-5502.2020.1.6.
Testo completoAbstract (sommario):
Introduction. The study focuses on the operation of a standalone membrane bioreactor applicable as an alternative to submerged membrane modules widely used as part of small capacity wastewater treatment facilities. Materials and methods. An ultra-filtration membrane was used to perform the research in a laboratory environment. The liquid, exposed to research, represented synthetic wastewater, whose composition was similar to the one of urban wastewaters, and it had varied concentrations of suspended solids (MLSS). The membrane element, produced by Raifil (Republic of Korea), that has capillary ultra-filtration membranes, was used in the experiments. The membrane pore size is 1 micron. The total membrane filter area is one square meter. This membrane module has standard characteristics (pore size, material), typical for ultra-filtration membranes; therefore, we can assume that any further results will not demonstrate any substantial discrepancies, if ultra-filtration membranes made by other manufacturers are used to conduct experiments. Results. The author describes a methodology for the optimization of pressure and MLSS values used in the process of membrane treatment. The author obtained the pressure values at which the amount of suspended solids in the filtered material shows a sharp rise, which means a slip of suspended solids into the filtrate, or a slip of contaminants. The author also identified the operating parameters that ensure maximal capacity. Conclusions. These findings help to outline a roadmap for further research into the optimization of membrane bioreactors (both standalone and submerged units) used in wastewater treatment.
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Subaer, Subaer, Hamzah Fansuri, Abdul Haris, Misdayanti Misdayanti, Imam Ramadhan, Teguh Wibawa, Yulprista Putri, Harlyenda Ismayanti e Agung Setiawan. "Pervaporation Membranes for Seawater Desalination Based on Geo–rGO–TiO2 Nanocomposites: Part 2—Membranes Performances". Membranes 12, n. 11 (26 ottobre 2022): 1046. http://dx.doi.org/10.3390/membranes12111046.
Testo completoAbstract (sommario):
This is part 2 of the research on pervaporation membranes for seawater desalination based on Geo–rGO–TiO2 nanocomposite. The quality of the Geo–rGO–TiO2 pervaporation membranes (PV), as well as the suitability of the built pervaporation system, is thoroughly discussed. The four membranes described in detail in the first article were tested for their capabilities using the parameters turbidity, salinity, total suspended solids (TSS), and electrical conductivity (EC). The membranes’ flux permeate was measured as a function of temperature, and salt rejection was calculated using the electrical conductivity values of the feed and permeate. Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) techniques were used to investigate changes in the chemical composition and internal structure of the membranes after use in pervaporation systems. The morphology of the membrane’s surfaces was examined by means of scanning electron microscopy (SEM), and the elemental distribution was observed by using X-ray mapping and energy dispersive spectroscopy (EDS). The results showed that the pervaporation membrane of Geo–rGO–TiO2 (1, 3) achieved a permeate flux as high as 2.29 kg/m2·h with a salt rejection of around 91%. The results of the FTIR and XRD measurements did not show any changes in the functional group and chemical compositions of the membrane after the pervaporation process took place. Long-term pressure and temperature feed cause significant cracking in geopolymer and Geo–TiO2 (3) membranes. SEM results revealed that the surface of all membranes is leached out, and elemental distribution based on X-ray mapping and EDS observations revealed the addition of Na+ ions on the membrane surface. The study’s findings pave the way for more research and development of geopolymers as the basic material for inorganic membranes, particularly with the addition of rGO–TiO2 nanocomposites.
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Aljlil, Saad A. "Fabrication of Bentonite–Silica Sand/Suspended Waste Palm Leaf Composite Membrane for Water Purification". Membranes 10, n. 10 (16 ottobre 2020): 290. http://dx.doi.org/10.3390/membranes10100290.
Testo completoAbstract (sommario):
In this study, a method for fabricating tubular ceramic membranes via extrusion using economical and locally available bentonite–silica sand and waste palm leaves was developed as a tool for conducting the necessary task of purifying water polluted with oil and suspended solid materials produced via various industrial processes. The developed tubular ceramic membranes were found to be highly efficient at separating the pollutants from water. The properties of the fabricated membrane were evaluated via mechanical testing, pore size distribution analysis, and contact angle measurements. The water contact angle of the fabricated membrane was determined to be 55.5°, which indicates that the membrane surface is hydrophilic, and the average pore size was found to be 66 nm. The membrane was found to demonstrate excellent corrosion resistance under acidic as well as basic conditions, with weight losses of less than 1% in each case. The membrane surface was found to be negatively charged and it could strongly repulse the negatively charged fine bentonite particles and oil droplets suspended in the water, thereby enabling facile purification through backwashing. The obtained ceramic membranes with desirable hydrophilic properties can thus serve as good candidates for use in ultrafiltration processes.
6
Ng, T. C. A., e H. Y. Ng. "Physico-chemical characterisation versus in situ micro-structural characterisation of membrane fouling in membrane bioreactors". Water Science and Technology 63, n. 8 (1 aprile 2011): 1781–87. http://dx.doi.org/10.2166/wst.2011.196.
Testo completoAbstract (sommario):
Fouling characteristics of aerobic submerged membrane bioreactors were analysed under two different membrane materials. Polyethersulfone (PES) membranes were found to foul faster at sub-critical flux than polyolefin (PO) membranes. Physico-chemical characterisation, by means of comparison of extracellular polymeric substances (EPS) and soluble microbial products (SMP) concentrations, as well as the mixed liquor suspended solids (MLSS) concentration were unable to explain the differences in membrane fouling of the contrasting membrane materials. The use of confocal laser scanning microscopy (CLSM) to image organic foulants directly on the membrane surface, coupled with image analyses showed that membrane fouling mechanism shifted from a biofilm initiated process on PO membranes to a bio-organic dominated process on PES membranes under sub-critical flux conditions. These results show that physico-chemical characterisation of an MBR process may not effectively distinguish the effectiveness of different membrane materials, so long as operating conditions are identical, and that characterisation of foulants on the membrane surfaces was necessary to elucidate the differences in membrane fouling.
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Park, Jiyeong, Seok-Hong Min, Won-Hee Lee, No-Suk Park, Hyung-Soo Kim e Jong-Oh Kim. "Properties and filtration performance of microporous metal membranes fabricated by rolling process". Journal of Water Reuse and Desalination 7, n. 1 (3 marzo 2016): 11–15. http://dx.doi.org/10.2166/wrd.2016.000.
Testo completoAbstract (sommario):
We evaluated the filtration performance of microporous metal membranes fabricated by the rolling process. Metal wire meshes were rolled with thickness reduction ratios of 10, 20, and 30%. The pore size of the metal wire mesh membrane decreased with increasing rolling ratio, whereas the removal efficiency of the suspended solids and turbidity showed a very slight increase compared to that of an unrolled mesh membrane. The metal powder was dispersed on the surface of the rolled metal wire mesh membrane and bound with polyvinyl alcohol, then dried at 100°C for 1 h, and finally sintered at 1,000°C for 3 h. The mean pore size, suspended solids, and turbidity of the metal powder membrane at a rolling ratio of 30% were approximately 0.7 μm, 84% and 83%, respectively. Therefore, microporous metal membranes successfully fabricated by the rolling process were also sufficiently permeable filters.
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Dada, Saubana Olorunsola, Chidambaram Thamariselvan, Mahmood Jebur e Sumith Ranil Wickramasinghe. "Innovative Approaches to Poultry Processing Wastewater Treatment: The Stainless Steel Ultrafiltration Membrane as a Viable Option". Membranes 13, n. 11 (11 novembre 2023): 880. http://dx.doi.org/10.3390/membranes13110880.
Testo completoAbstract (sommario):
In pursuit of sustainability, we explored replacing conventional dissolved air floatation (DAF) in poultry processing wastewater (PPW) treatment with a precisely tuned 0.02 µm stainless-steel ultrafiltration (SSUF) membrane. SSUF is a robust, homogenously porous membrane with strong chemical resistance, ease of cleaning, and exceptional resistance to organic fouling. Unlike polymeric membranes, it can be regenerated multiple times, making it a cost-effective choice due to its compatibility with harsh chemical cleaning. The PPW used for the study was untreated wastewater from all processing units and post-initial screening. Our study revealed the SSUF membrane’s exceptional efficiency at eliminating contaminants. It achieved an impressive removal rate of up to 99.9% for total suspended solids (TSS), oil, grease, E. coli, and coliform. Additionally, it displayed a notable reduction in chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total Kjeldahl nitrogen (TKN), up to 90%, 76%, and 76%, respectively. Our investigation further emphasized the SSUF membrane’s ability in pathogen removal, affirming its capacity to effectively eradicate up to 99.99% of E. coli and coliform. The measured critical flux of the membrane was 48 Lm−2h−1 at 38 kPa pressure and 1.90 m/s cross-flow velocity. In summary, our study highlights the considerable potential of the SSUF membrane. Its robust performance treating PPW offers a promising avenue for reducing its environmental impact and advocating for sustainable wastewater management practices.
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Fraga, Maria C., Rosa M. Huertas, João G. Crespo e Vanessa J. Pereira. "Novel Submerged Photocatalytic Membrane Reactor for Treatment of Olive Mill Wastewaters". Catalysts 9, n. 9 (13 settembre 2019): 769. http://dx.doi.org/10.3390/catal9090769.
Testo completoAbstract (sommario):
A new hybrid photocatalytic membrane reactor that can easily be scaled-up was designed, assembled and used to test photocatalytic membranes developed using the sol–gel technique. Extremely high removals of total suspended solids, chemical oxygen demand, total organic carbon, phenolic and volatile compounds were obtained when the hybrid photocatalytic membrane reactor was used to treat olive mill wastewaters. The submerged photocatalytic membrane reactor proposed and the modified membranes represent a step forward towards the development of new advanced treatment technology able to cope with several water and wastewater contaminants.
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Lorain, Olivier, Sébastien Marcellino, André Deratani, Sana Gassara, Isabelle Duchemin e Jean-Michel Espenan. "New ultrafiltration (UF) membrane made with a new polymer material for long-lasting rejection performance, Neophil®". Water Practice and Technology 15, n. 2 (19 marzo 2020): 356–64. http://dx.doi.org/10.2166/wpt.2020.022.
Testo completoAbstract (sommario):
Abstract This paper focuses on the development of a new membrane, named Neophil®, with durable performance using a new amphiphilic nanostructured dibloc-copolymer (BCP) composed of one hydrophilic bloc and one hydrophobic bloc which is anchored deeply and permanently in the polymer matrix (PVDF, Kynar resin Arkema) of the membrane. Compared to conventional membranes, particle rejections (suspended solids, microplastics, bacteria and viruses) have been shown to be maintained through accelerated ageing experiments. In this paper, this new membrane technology is described and its durability is demonstrated and compared with other membranes of the market.
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Argurio, Pietro, Enrica Fontananova, Raffaele Molinari e Enrico Drioli. "Photocatalytic Membranes in Photocatalytic Membrane Reactors". Processes 6, n. 9 (7 settembre 2018): 162. http://dx.doi.org/10.3390/pr6090162.
Testo completoAbstract (sommario):
The present work gives a critical overview of the recent progresses and new perspectives in the field of photocatalytic membranes (PMs) in photocatalytic membrane reactors (PMRs), thus highlighting the main advantages and the still existing limitations for large scale applications in the perspective of a sustainable growth. The classification of the PMRs is mainly based on the location of the photocatalyst with respect to the membranes and distinguished in: (i) PMRs with photocatalyst solubilized or suspended in solution and (ii) PMRs with photocatalyst immobilized in/on a membrane (i.e., a PM). The main factors affecting the two types of PMRs are deeply discussed. A multidisciplinary approach for the progress of research in PMs and PMRs is presented starting from selected case studies. A special attention is dedicated to PMRs employing dispersed TiO2 confined in the reactor by a membrane for wastewater treatment. Moreover, the design and development of efficient photocatalytic membranes by the heterogenization of polyoxometalates in/on polymeric membranes is discussed for applications in environmental friendly advanced oxidation processes and fine chemical synthesis.
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Al-Ani, Faris H., Qusay F. Alsalhy, Rawia Subhi Raheem, Khalid T. Rashid e Alberto Figoli. "Experimental Investigation of the Effect of Implanting TiO2-NPs on PVC for Long-Term UF Membrane Performance to Treat Refinery Wastewater". Membranes 10, n. 4 (21 aprile 2020): 77. http://dx.doi.org/10.3390/membranes10040077.
Testo completoAbstract (sommario):
This study investigated the impact of implanting TiO2-NPs within a membrane to minimize the influence of long-term operation on the membrane characteristics. Four poly vinyle chloride-titanium oxide (PVC-TiO2-NPs) membranes were prepared to create an ultrafiltration membrane (UF) that would effectively treat actual refinery wastewater. The hypothesis of this work was that TiO2-NPs would function as a hydrophilic modification of the PVC membrane and excellent self-cleaning material, which in turn would greatly extend the membrane’s lifetime. The membranes were characterized via Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), atomic force microscope (AFM), and scanning electron microscope (SEM). The removal efficiency of turbidity, total suspended solid (TSS), oil and grease, heavy metals and chemical oxygen demand (COD) were investigated. Contact angle (CA) reduced by 12.7% and 27.5% on the top and bottom surfaces, respectively. The PVC membrane with TiO2-NPs had larger mean pore size on its surface and more holes with larger size inside the membrane structure. The addition of TiO2-NPs could remarkably enhance the antifouling property of the PVC membrane. The pure water permeability (PWP) of the membrane was enhanced by 95.3% with an increase of TiO2 to 1.5 gm/100gm. The PWP after backwashing was reduced from 22.3% for PVC to 10.1% with 1.5 gm TiO2-NPs. The long-term performance was improved from five days for PVC to 23 d with an increase in TiO2-NPs to 1.5 gm. The improvements of PVC-TiO2-NPs long-term were related to the enhancement of the hydrophilic character of the membrane and increase tensile strength due to the reinforcement effect of TiO2-NPs. These results clearly identify the impact of the TiO2-NPs content on the long-term PVC/TiO2-NPs performance and confirm our hypothesis that it is possible to use TiO2-NPs to effectively enhance the lifetime of membranes during their long-term operation.
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Yeremeyv, P. G., e D. B. Kiselev. "Thin Sheet Metal (Membrane) Suspended Roof Structures". International Journal of Space Structures 10, n. 4 (dicembre 1995): 237–41. http://dx.doi.org/10.1177/026635119501000406.
Testo completoAbstract (sommario):
A membrane roof is a three-dimensional system of thin metal sagging sheets fastened along the perimeter to the supporting contour. The membrane can form the roof of buildings and structures of various shapes of the surface and in-plan outlines with spans of 18 to 300 m. The longer the span the higher the economic efficiency of the membranes, the thickness of which is as low as 1 to 5 mm. The distinctive features of the structure are the most complete use of strength properties of a thin sheet in compression and the continuation in one material of load bearing and enclosure functions. Such a structure is able to resist all types of force actions, wind and seismic ones being among them. The thin-sheet roof are easy to manufacture and erect. The membrane structures are intended for civil and industrial buildings. At present a wide complex of theoretical and experimental studies of the membrane structures is being carried out.
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Soto-Herranz, María, Mercedes Sánchez-Báscones, María Cruz García-González e Pablo Martín-Ramos. "Comparison of the Ammonia Trapping Performance of Different Gas-Permeable Tubular Membrane System Configurations". Membranes 12, n. 11 (5 novembre 2022): 1104. http://dx.doi.org/10.3390/membranes12111104.
Testo completoAbstract (sommario):
The technology of gas-permeable tubular membranes (GPMs) is promising in reducing ammonia emissions from livestock manure, capturing NH3 in an acidic solution, and obtaining final products suitable for valorization as fertilizers, in line with the principles of the circular economy. This study aimed to evaluate the performance of several e-PTFE membrane systems with different configurations for the recovery of NH3 released from pig slurry. Ten different configurations were tested: only a submerged membrane, only a suspended membrane in the same chamber, only a suspended membrane in an annex chamber, a submerged membrane + a suspended membrane in the same chamber, and a submerged membrane + a suspended membrane in an annex chamber, considering in each case the scenarios without and with agitation and aeration of the slurry. In all tests, sulfuric acid (1N H2SO4) was used as the NH3 capture solution, which circulated at a flow rate of 2.1 L·h−1. The results showed that NH3-N removal rates ranged from 36–39% (for systems with a single submerged or suspended membrane without agitation or aeration of the slurry) to 70–72% for submerged + suspended GPM systems with agitation and aeration. In turn, NH3-N recovery rates were found to be between 44–54% (for systems with a single membrane suspended in an annex compartment) and 88–91% (for systems based on a single submerged membrane). However, when choosing a system for farm deployment, it is essential to consider not only the capture and recovery performance of the system, but also the investment and operating costs (ranging from 9.8 to 21.2 €/kg N recovered depending on the selected configuration). The overall assessment suggests that the simplest systems, based on a single membrane, may be the most recommendable.
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Makisha, Nikolay. "Membrane bioreactors for treatment of galvanic wastewater". E3S Web of Conferences 97 (2019): 05047. http://dx.doi.org/10.1051/e3sconf/20199705047.
Testo completoAbstract (sommario):
The article speaks about the membrane methods applied for treatment of galvanic sewage. It reveals the main features and peculiarities, which determine the maintenance of various types of membranes for industrial wastewater treatment. Ultrafiltration is a method that uses a membrane to separate by size ions of heavy metals, petroleum products, macromolecules and suspended solids. Application of ceramic membranes in ultrafiltration plants allows implementing of various technological processes with resource-saving opportunities, such as treatment of galvanic workshops sewage with efficiency of 99% and entire restoration of the worked out solutions. Nanofiltration is a process of membrane filtration of wastewater, which ensures the removal of multi-charged ions from water, depending on the size. Reverse osmosis is a process that is used to desalinate the bulk of dissolved salts in wastewater of various industries. In addition, this process is used to ensure the purification of effluents from organic and inorganic compounds, suspended solids and high molecular weight compounds.
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Sannigrahi, Achinta, Vishwesh Haricharan Rai, Muhsin Vannan Chalil, Debayani Chakraborty, Subrat Kumar Meher e Rahul Roy. "A Versatile Suspended Lipid Membrane System for Probing Membrane Remodeling and Disruption". Membranes 12, n. 12 (25 novembre 2022): 1190. http://dx.doi.org/10.3390/membranes12121190.
Testo completoAbstract (sommario):
Artificial membrane systems can serve as models to investigate molecular mechanisms of different cellular processes, including transport, pore formation, and viral fusion. However, the current, such as SUVs, GUVs, and the supported lipid bilayers suffer from issues, namely high curvature, heterogeneity, and surface artefacts, respectively. Freestanding membranes provide a facile solution to these issues, but current systems developed by various groups use silicon or aluminum oxide wafers for fabrication that involves access to a dedicated nanolithography facility and high cost while conferring poor membrane stability. Here, we report the development, characterization and applications of an easy-to-fabricate suspended lipid bilayer (SULB) membrane platform leveraging commercial track-etched porous filters (PCTE) with defined microwell size. Our SULB system offers a platform to study the lipid composition-dependent structural and functional properties of membranes with exceptional stability. With dye entrapped in PCTE microwells by SULB, we show that sphingomyelin significantly augments the activity of pore-forming toxin, Cytolysin A (ClyA) and the pore formation induces lipid exchange between the bilayer leaflets. Further, we demonstrate high efficiency and rapid kinetics of membrane fusion by dengue virus in our SULB platform. Our suspended bilayer membrane mimetic offers a novel platform to investigate a large class of biomembrane interactions and processes.
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Cano, Grégory, e Philippe Moulin. "Treatment of Boiler Condensate by Ultrafiltration for Reuse". Membranes 12, n. 12 (19 dicembre 2022): 1285. http://dx.doi.org/10.3390/membranes12121285.
Testo completoAbstract (sommario):
The generation of water vapor is crucial for the petrochemical industry. In order to protect the boiler from damage, the re-injected water must not contain any suspended matter, especially hydrocarbons. Moreover, it is condensed steam with a temperature close to 100 °C and the unintentional creation or chronic generation of pollution, respectively, that can more or less produce the concentrated pollution. In this context, membrane processes appear promising in order to achieve this reuse and more especially crossflow ceramic membranes. The novelty of this paper is to study the retention of hydrocarbons and suspended solids contained in the condensate hot water of a high-capacity boiler using ceramic ultrafiltration membranes. In total, two ultrafiltration molecular weight cut-offs were used: 50–150 kDa. Several operating parameters were studied such as effluent type (accidental or chronic pollution), temperature, transmembrane pressure, initial volume, and pilot plant size. In all cases, retention of suspended matter was above 90% and residual hydrocarbon concentrations were under 0.1 ppm even for high-volume concentrations. Control of the transmembrane pressure and the molecular weight cut-off of the membrane are key to optimizing the process. Despite the high-volume concentration obtained, the membranes were perfectly regenerated with conventional cleaning procedures.
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Agana, Bernard A., Darrell Reeve e John D. Orbell. "Industrial water reclamation using polymeric membranes – case studies involving a car manufacturer and a beverage producer". Journal of Water Reuse and Desalination 3, n. 4 (17 luglio 2013): 357–72. http://dx.doi.org/10.2166/wrd.2013.004.
Testo completoAbstract (sommario):
This study presents the evaluation of different polymeric membranes for the reclamation of wastewater generated by two manufacturers. Specifically, ultrafiltration (UF) membranes were evaluated for wastewater pretreatment use while nanofiltration (NF) and reverse osmosis (RO) membranes were evaluated for wastewater reclamation use. Results show that both the UF membranes used were not suitable for pretreatment of the oily wastewater stream due to the presence of suspended cathodic electrodeposition (CED) paint particles. The CED paint particles rapidly deposit on the membrane surface resulting in severe fouling and very low permeate fluxes. With respect to the metals and beverage wastewater streams, the polyvinylidine-difluoride (PVDF) UF membrane was shown to be more suitable for pretreatment than the polyacrylonitrile UF membrane. The PVDF-UF membrane had relatively lower flux decline rates, higher turbidity and higher total organic carbon reduction rates. Meanwhile, the low-pressure RO membrane proved to be suitable for wastewater reclamation of the oily and beverage wastewater streams – showing low flux decline rates, high conductivity and high chemical oxygen demand reduction rates. In terms of reclaiming the metals wastewater stream, the NF membrane proved more suitable than the low-pressure RO membrane. The NF membrane had relatively higher permeate fluxes and metals rejection rates compared to the RO membrane.
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Rezakazemi, Mashallah, Mohsen Maghami e Toraj Mohammadi. "High Loaded Synthetic Hazardous Wastewater Treatment Using Lab-Scale Submerged Ceramic Membrane Bioreactor". Periodica Polytechnica Chemical Engineering 62, n. 3 (22 novembre 2017): 299–304. http://dx.doi.org/10.3311/ppch.11459.
Testo completoAbstract (sommario):
Submerged ceramic membrane bioreactors (SCMBRs) are more efficient combinations of traditional activated hazardous sludge and new membrane separation processes in wastewater treatment. Suspended solids are separated from hazardous effluent using microfilter ceramic membranes in SCMBRs. A high loaded wastewater was treated using an SCMBR employing a homemade tubular ceramic membrane in laboratory scale. Hydraulic Retention Time (HRT) was 32 h and COD range was varied from 2000 to 5000 mg/l. COD removal was evaluated to be more than 90% after a week and the lab scale SCMBR showed desired performance for the wastewater treatment. Mixed Liquor Suspended Solid (MLSS) was increased from 2000 to 4000 mg/L during the SCMBR operation time.
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Nechytailo, Mykola, Olena Nahorna e Yevhenii Kosiuk. "Defining the effect of the chemical concentration and solution pH on membrane chemical cleaning process". E3S Web of Conferences 109 (2019): 00061. http://dx.doi.org/10.1051/e3sconf/201910900061.
Testo completoAbstract (sommario):
In the process of treating natural water from surface sources, precipitated substances are tend to be deposited on the ultrafiltration membrane, either as suspended solids or as gel structures, formed by humic substances with metal salts. Hydraulic washes are unable to remove gelled structures from the surface of the membranes. Consequently, the phenomenon of gelation on the surface of the membrane causes gradual decrease in productivity, which is a negative factor. Chemical washing of membranes is generally used to remove the gel layer from the membrane surface. In this paper, the range of compositions which effectively remove complex contaminants is proposed, and also the efficacy of both pH and changes in the concentration of active substances on the process of washing the membrane are analyzed.
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Oro, Carolina E. Demaman, Bruna M. Saorin Puton, Luciana D. Venquiaruto, Rogério Marcos Dallago, Giordana Demaman Arend e Marcus V. Tres. "The Role of Membranes in Modern Winemaking: From Clarification to Dealcoholization". Membranes 15, n. 1 (9 gennaio 2025): 14. https://doi.org/10.3390/membranes15010014.
Testo completoAbstract (sommario):
The utilization of membrane technologies in winemaking has revolutionized various stages of production, offering precise and efficient alternatives to traditional methods. Membranes, characterized by their selective permeability, play a pivotal role in enhancing wine quality across multiple processes. In clarification, microfiltration and ultrafiltration membranes, such as ceramic or polymeric membranes (e.g., polyethersulfone or PVDF), effectively remove suspended solids and colloids, resulting in a clearer wine without the need for chemical agents. During stabilization, membranes such as nanofiltration and reverse osmosis membranes, often made from polyamide composite materials, enable the selective removal of proteins, polysaccharides, and microorganisms, thereby improving the wine’s stability and extending its shelf life. Additionally, in dealcoholization, membranes like reverse osmosis and pervaporation membranes, typically constructed from polydimethylsiloxane (PDMS) or other specialized polymers, facilitate the selective removal of ethanol while preserving the wine’s flavor and aroma profile, addressing the increasing consumer demand for low-alcohol and alcohol-free wines. This article provides a comprehensive analysis of the advancements and applications of membrane technologies in winemaking.
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Romay, Marta, Nazely Diban, Maria J. Rivero, Ane Urtiaga e Inmaculada Ortiz. "Critical Issues and Guidelines to Improve the Performance of Photocatalytic Polymeric Membranes". Catalysts 10, n. 5 (19 maggio 2020): 570. http://dx.doi.org/10.3390/catal10050570.
Testo completoAbstract (sommario):
Photocatalytic membrane reactors (PMR), with immobilized photocatalysts, play an important role in process intensification strategies; this approach offers a simple solution to the typical catalyst recovery problem of photocatalytic processes and, by simultaneous filtration and photocatalysis of the aqueous streams, facilitates clean water production in a single unit. The synthesis of polymer photocatalytic membranes has been widely explored, while studies focused on ceramic photocatalytic membranes represent a minority. However, previous reports have identified that the successful synthesis of polymeric photocatalytic membranes still faces certain challenges that demand further research, e.g., (i) reduced photocatalytic activity, (ii) photocatalyst stability, and (iii) membrane aging, to achieve technological competitiveness with respect to suspended photocatalytic systems. The novelty of this review is to go a step further to preceding literature by first, critically analyzing the factors behind these major limitations and second, establishing useful guidelines. This information will help researchers in the field in the selection of the membrane materials and synthesis methodology for a better performance of polymeric photocatalytic membranes with targeted functionality; special attention is focused on factors affecting membrane aging and photocatalyst stability.
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Shi, Li, Deyu Li, Choongho Yu, Wanyoung Jang, Dohyung Kim, Zhen Yao, Philip Kim e Arunava Majumdar. "Measuring Thermal and Thermoelectric Properties of One-Dimensional Nanostructures Using a Microfabricated Device". Journal of Heat Transfer 125, n. 5 (23 settembre 2003): 881–88. http://dx.doi.org/10.1115/1.1597619.
Testo completoAbstract (sommario):
We have batch-fabricated a microdevice consisting of two adjacent symmetric silicon nitride membranes suspended by long silicon nitride beams for measuring thermophysical properties of one-dimensional nanostructures (nanotubes, nanowires, and nanobelts) bridging the two membranes. A platinum resistance heater/thermometer is fabricated on each membrane. One membrane can be Joule heated to cause heat conduction through the sample to the other membrane. Thermal conductance, electrical conductance, and Seebeck coefficient can be measured using this microdevice in the temperature range of 4–400 K of an evacuated Helium cryostat. Measurement sensitivity, errors, and uncertainty are discussed. Measurement results of a 148 nm and a 10 nm-diameter single wall carbon nanotube bundle are presented.
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Mizogami, Maki, e Hironori Tsuchiya. "Lipid Composition-, Medium pH-, and Drug-Concentration-Dependent Membrane Interactions of Ibuprofen, Diclofenac, and Celecoxib: Hypothetical Association with Their Analgesic and Gastrointestinal Toxic Effects". Future Pharmacology 4, n. 2 (20 giugno 2024): 437–49. http://dx.doi.org/10.3390/futurepharmacol4020024.
Testo completoAbstract (sommario):
Among nonsteroidal anti-inflammatory drugs, ibuprofen, diclofenac, and celecoxib have been frequently used in multimodal analgesia. Recent studies challenge the conventional theory that they exhibit activity and toxicity by acting on cyclooxygenase selectively. We compared their membrane interactions that may be associated with analgesic and gastrointestinal toxic effects. Biomimetic membranes suspended in buffers of different pH were prepared with 1-palmitoyl-2-oleoylphosphatidylcholine, sphingomyelin, and cholesterol to mimic neuronal membranes and with 1,2-dipalmitoylphosphatidylcholine to mimic gastrointestinal mucosae. The membrane interactivity was determined by measuring fluorescence polarization. At pH 7.4, the drugs interacted with neuro-mimetic membranes to decrease membrane fluidity at pharmacokinetically-relevant 0.5–100 μM. Celecoxib was most potent, followed by ibuprofen and diclofenac. At pH 4.0 and 2.5, however, the drugs increased the fluidity of 1,2-dipalmitoylphosphatidylcholine membranes at 0.1–1 mM, corresponding to gastroduodenal lumen concentrations after administration. Their membrane fluidization was greater at gastric pH 2.5 than at duodenal pH 4.0. Low-micromolar ibuprofen, diclofenac, and celecoxib structure specifically decrease neuronal membrane fluidity, which hypothetically could affect signal transmission of nociceptive sensory neurons. Under gastroduodenal acidic conditions, high-micromolar ibuprofen, diclofenac, and celecoxib induce fluidity increases of membranous phosphatidylcholines that are hypothetically associated with gastrointestinal toxic effects, which would enhance acid permeability of protective mucosal membranes.
25
Fazullin, D. D., G. V. Mavrin e V. O. Dryakhlov. "Stabilization of the Dynamic Layer of Composite Membranes by UV Radiation". Elektronnaya Obrabotka Materialov 58, n. 3 (giugno 2022): 62–69. http://dx.doi.org/10.52577/eom.2022.58.3.62.
Testo completoAbstract (sommario):
To stabilize the dynamic layer of cellulose acetate (CA) and polystyrene (PS) membranes, the membrane was exposed to UV radiation using a laboratory setup in atmospheric air. As a base for dynamic membranes, a micro-filtration membrane made of nylon-66 and a membrane made of polytetrafluoroethylene (PTFE) grade MFFC-3G were used. Dynamic membranes PTFE-CA, PTFE-PSd nylon-CA, nylon-PS were obtained by forming a semi-permeable layer on the surface of a porous base from suspended microparticles of PS or CA present in a filtered aqueous solution of acetone with sizes of 81–504 nm and 42–130 nm, respectively, in a dynamic equilibrium with the solution. After obtaining the membranes, the surface was treated for 10 minutes with UV radiation in the wavelength range of 280–320 nm, with a UV radiation power of 36 W. Stabilization of dynamic membranes by UV radiation made it possible to increase the specific productivity of CA membranes 10 times and of PS by 1.5 times, while reducing the retention capacity of those membranes in terms of oil products by 9–17%. UV treatment of polymeric membranes can be used to increase the specific productivity and stabilization of dynamic membranes with a PS surface layer.
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Botterbusch, Samuel, e Tobias Baumgart. "Interactions between Phase-Separated Liquids and Membrane Surfaces". Applied Sciences 11, n. 3 (31 gennaio 2021): 1288. http://dx.doi.org/10.3390/app11031288.
Testo completoAbstract (sommario):
Liquid-liquid phase separation has recently emerged as an important fundamental organizational phenomenon in biological settings. Most studies of biological phase separation have focused on droplets that “condense” from solution above a critical concentration, forming so-called “membraneless organelles” suspended in solution. However, membranes are ubiquitous throughout cells, and many biomolecular condensates interact with membrane surfaces. Such membrane-associated phase-separated systems range from clusters of integral or peripheral membrane proteins in the plane of the membrane to free, spherical droplets wetting membrane surfaces to droplets containing small lipid vesicles. In this review, we consider phase-separated liquids that interact with membrane surfaces and we discuss the consequences of those interactions. The physical properties of distinct liquid phases in contact with bilayers can reshape the membrane, and liquid-liquid phase separation can construct membrane-associated protein structures, modulate their function, and organize collections of lipid vesicles dynamically. We summarize the common phenomena that arise in these systems of liquid phases and membranes.
27
Vainrot, Nataly, Moris S. Eisen e Raphael Semiat. "Membranes in Desalination and Water Treatment". MRS Bulletin 33, n. 1 (gennaio 2008): 16–20. http://dx.doi.org/10.1557/mrs2008.9.
Testo completoAbstract (sommario):
AbstractMembrane techniques for water treatment have been growing significantly for the last decade. Reverse osmosis, for example, is the leading seawater desalination technique. Nanofiltration membranes are used more and more for hardness removal and even to desalinate slightly polluted waters. Ultrafiltration and microfiltration membranes are used extensively mainly as membrane bioreactors in wastewater recovery. While this trend is growing, the membranes still may be improved significantly, based on new materials designed to increase the flux of water through the membranes at reduced pressures while maintaining or even improving the rejection of dissolved matter or suspended matter. Better membranes will reduce energy consumption while maintaining affordable separation properties.
28
Fakhru'l-Razi, A., e M. J. M. M. Noor. "Treatment of palm oil mill effluent (POME) with the membrane anaerobic system (MAS)". Water Science and Technology 39, n. 10-11 (1 maggio 1999): 159–63. http://dx.doi.org/10.2166/wst.1999.0647.
Testo completoAbstract (sommario):
One of the major difficulties in anaerobic wastewater treatment processes is the need to retain a sufficient quantity of active biomass in the anaerobic reactor. The use of membranes to achieve external solid/liquid phase separation will result in the retention of the biomass at the surface of the membranes. In this study, the Membrane Anaerobic System (MAS) was used to treat industrial wastewater from a palm oil mill. The MAS was subjected to increasing organic loading rates (OLR) and a total of six steady states were attained. The first steady state influent COD concentration was 39,910 mg/l increasing to the final or sixth steady state COD concentration of 68,310 mg/l. The efficiency of COD removal was between 91.7 to 94.2 percent with an average HRT of 3.03 days. The maximum OLR applied during the sixth steady state was 21.7 kgCOD/m3/d. The reactor mixed liquor suspended solids (MLSS) was between 50,000 to 57,000 mg/l while the percentage of the mixed liquor volatile suspended solids (MLVSS) was between 74 to 82 percent. A crossflow ultraftration (UF) module was used to filter the final effluent and simultaneously retain biomass in the anaerobic reactor. A clear final effluent was produced but membrane flux rate deterioration was observed due to membrane fouling. Membrane fouling could be minimised with faster crossflow feed velocities and regular membrane flushing.
29
Yue, Caide, Hongmin Dong, Yongxing Chen, Bin Shang, Yi Wang, Shunli Wang e Zhiping Zhu. "Direct Purification of Digestate Using Ultrafiltration Membranes: Influence of Pore Size on Filtration Behavior and Fouling Characteristics". Membranes 11, n. 3 (3 marzo 2021): 179. http://dx.doi.org/10.3390/membranes11030179.
Testo completoAbstract (sommario):
Ultrafiltration (UF) can effectively remove large particles, suspended solids, and colloidal substances from anaerobic digestate. However, membrane fouling is a technical challenge in the purification of the digestate by UF. In this study, polyethersulfone (PES) membranes with four pore sizes (50.0, 20.0, 10.0 and 5.0 kDa) were employed to filter anaerobic digestate from swine manure. The effects of temperature, transmembrane pressure (TMP), and cross-flow velocity (CFV) on flux were investigated. The purification effects and fouling characteristics of the four membranes were analyzed. The results revealed that the increase of temperature and CFV can effectively promote UF separation efficiency, but as the TMP exceeded 3.0 bar, the flux increase rates of the four membranes were almost zero. The larger membrane pore size caused the faster flux increase with the increase in pressure. During the batch experiment, the 20.0 kDa membrane showed the lowest flux maintenance ability, while the 5.0 kDa showed the highest ability due to the smaller pore size. All four membranes can effectively remove tetracyclines residues. Elements C, O, and S were the major membrane foulant elements. The dominant bacteria orders of membrane fouling were Pseudomonadales, Xanthomonadales and Burkholderiales. Compared with tap water and citric acid, the membrane cleaning by NaOH and NaClO showed higher flux recovery rates. The 50.0 kDa membrane achieved the best cleaning effects under all cleaning methods.
30
Yuliwati, Erna, Ahmad Fauzi Ismail, Amrifan Saladin Mohruni e Agung Mataram. "Optimum parameters for treating coolant wastewater using PVDF-membrane". MATEC Web of Conferences 156 (2018): 08011. http://dx.doi.org/10.1051/matecconf/201815608011.
Testo completoAbstract (sommario):
Chemical oxygen demand (COD removal on ultrafiltration membrane were studied from treating of coolant wastewater. The membranes were fabricated via the dry-jet wet spinning method. The experiment was conducted using synthetic coolant wastewater as effluent, and an experimental set-up consist of membrane reservoir was used throughout the investigation. Deposition and accumulation of suspended solids on the membrane surface during filtration were prohibited with continuous aeration. Membrane performance was measured as well as flux and COD removal efficiency. The RSM was performed to investigate the optimised process conditions for treating coolant wastewater. Results using RSM-approximation have demonstrated the improvement in COD removal of 99.63%. This improvement is achieved by optimised process conditions of mixed liquor suspended solids (MLSS) concentration, air bubble flow rate (ABFR), hydraulic retention time (HRT) and pH at 6.00 g/L, 3.05 ml/min, 280.50 min, and 6.50 respectively.
31
Utomo, Dani Puji, Tutuk Djoko Kusworo, Andri Cahyo Kumoro, Budiyono Budiyono e Tonni Agustiono Kurniawan. "Current Trend of MOFs Incorporated Membranes for Advanced Wastewater Treatment". ASEAN Journal of Chemical Engineering 23, n. 3 (29 dicembre 2023): 370. http://dx.doi.org/10.22146/ajche.83845.
Testo completoAbstract (sommario):
Membrane technology has gained attention in wastewater treatment due to its great potential for producing high-grade water products for reuse. The membrane also effectively removes persistent pollutants in water effluent. However, their application is constrained by low productivity due to fouling formation. Incorporating functionalized nanoparticles into polymeric membranes has attracted much attention due to the improved membrane performance and additional features. Metal-organic frameworks (MOFs) incorporated into polymeric membranes have been widely applied in reverse osmosis (RO), forward osmosis (FO), nanofiltration (NF), and microfiltration (MF) for water and wastewater treatment. This short review presented recent findings, fabrication methods, and a systematic understanding of transport mechanisms under various operating conditions. This study also focused on several important parameters, such as improving physicochemical properties, membrane features, and performance enhancement in wastewater treatment. The reported studies show that MOFs incorporated membranes have reached >95% organic pollutants and 100% suspended solids. The membrane durability was also enhanced up to 140%, and the flux recovery can be maintained at 98% after several cycles. Even some MOFs, such as ZIF-8 and UiO-66, exhibited excellent performance in harsh conditions (pH < 4). The prospects and challenges of MOFs-incorporated membranes in industrial applications were also provided in this study.
32
Khaless, Khaoula, Brahim Achiou, Rachid Boulif e Rachid Benhida. "Recycling of Spent Reverse Osmosis Membranes for Second Use in the Clarification of Wet-Process Phosphoric Acid". Minerals 11, n. 6 (16 giugno 2021): 637. http://dx.doi.org/10.3390/min11060637.
Testo completoAbstract (sommario):
Various techniques have been used to “clean-up” wet-process phosphoric acid such as precipitation, flotation and adsorption. To address the potential of membrane processes in the phosphoric acid clarification process, this study explores the benefits of membrane techniques as a green separation technique for phosphoric acid clarification in an eco-efficient way through the use of recycling spent reverse osmosis membrane. Regenerated membrane was used to study the phosphoric acid clarification at a laboratory scale. They were immersed in an oxidizer for at most seven days. The samples were characterized systematically before immersion in an oxidant media. In this study, the potential to regenerate spent membranes and application of this media to clarify the 29% P2O5 phosphoric acid was demonstrated. This study shows, through experiments, that the reverse osmosis (RO) membranes could achieve a rejection of 70% and 61% for suspended solid and organic matter, respectively. These promising results will pave the way for implementation of these membranes in phosphoric acid treatment. Moreover, besides being economically advantageous, the use of the spent membrane is likely an environmentally friendly route (no waste, no organic solvent and effluent to be regenerated later on).
33
Li, Ying. "The application of PVC hollow fiber ultrafiltration membrane in ultra-low permeability oilfield". Journal of Physics: Conference Series 2834, n. 1 (1 ottobre 2024): 012030. http://dx.doi.org/10.1088/1742-6596/2834/1/012030.
Testo completoAbstract (sommario):
Abstract Oil containing wastewater produced from ultra-low permeability oil fields generally needs to be treated to meet the 5-1-1 standard before it can be reinjected. In order to meet the standards for treating oily wastewater in ultra-low permeability oil fields, PVC hollow fiber ultrafiltration membranes and pre-treatment processes for removing oil, suspended solids, sulfides, etc. before the membrane were selected. The application shows that the aeration air flotation flow sand filtration PVC hollow fiber ultrafiltration membrane process can treat oily wastewater, and the treated water can reach the “5-1-1” standard. In the pre-treatment process of PVC hollow fiber ultrafiltration membrane, the silicone rubber membrane aeration device has good oxidation effect, high efficiency in micro nano air flotation for oil removal and suspended solids, and easy management of sand flow filters. This process has economic feasibility and provides technical support for the treatment of oily wastewater in ultra-low permeability oil fields, with great promotional value.
34
Santosa, Imam, Daria Br Ginting e Enro Sujito. "Performance of pretreatment materials on hospital wastewater before microfiltration membrane filtration process". Applied Research in Science and Technology 2, n. 1 (25 agosto 2022): 36–42. http://dx.doi.org/10.33292/areste.v2i1.22.
Testo completoAbstract (sommario):
An alternative method of treating hospital wastewater can use a microfiltration membrane, where the results showed that the disposal of oily wastewater reached 82.5%, BOD 90%, COD 85%, and total Coli up to 70%. In addition, it can remove particles from wastewater from 0.04 to 100 microns in size. The problem with using microfiltration membranes is the rapid occurrence of fouling/saturation on the surface of the microfiltration membrane, causing the wastewater treatment operation time to be short. The length of this treatment causes the problem of less amount of wastewater being treated and another problem, namely faster membrane replacement. This study aims to determine the performance of pretreatment of microfiltration membranes made of alum, silica sand, and activated carbon for parameters pH, BOD, COD, TSS, Ammonia, Fatty Oil, and Total Coliform. The results of the study were as follows: 1) the average quality of hospital wastewater was temperature 28.8°C, pH 7, BOD 79 mg/l, COD 167.05 mg/l, Total Suspended Solid 68 mg/l, Ammonia 4 mg/l, Phosphate 0.745 mg/l, Fatty Oil 1.64 mg/l, Coliform 2.200 MPN/100 ml. 2) Comparison analysis of the most effective materials on the parameters, for BOD Silica Sand 78.24%, COD 56.25% Silica Sand, Total Suspended Solids 83.42% Activated Carbon, Ammonia Silica Sand 56.49%, Phosphate 80.43 % Activated Carbon, Fat Oil is 80.43% Alum, Coliform is Microfiltration Membrane 40.91%.
35
Mora, Pérez, Quezada, Herrera, Cassano e Ruby-Figueroa. "Impact of Membrane Pore Size on the Clarification Performance of Grape Marc Extract by Microfiltration". Membranes 9, n. 11 (6 novembre 2019): 146. http://dx.doi.org/10.3390/membranes9110146.
Testo completoAbstract (sommario):
The influence of membrane pore size on the permeate flux, fouling mechanism, and rejection of soluble and suspended solids, as well as of phenolics and anthocyanins, in the clarification of grape marc extract by microfiltration (MF) was studied. MF was operated by using three monotubular ceramic membranes with a pore size of 0.14, 0.2, and 0.8 µm, respectively, according to a batch concentration configuration in selected operating conditions (2.25 bar as operating pressure, 4.93 L/min as feed flow rate, and 25 °C as operating temperature). No significant differences in the permeate flux values were appreciated despite the difference in pore size. The mathematical analyses of the flux behavior revealed that intermediate pore blocking is the predominant mechanism for 0.14 and 0.2 µm membranes, whereas complete pore blocking prevails for the 0.8 µm membrane. Differences in the fouling mechanism were associated with differences in the total phenols rejection: the highest rejection was observed for the 0.8 µm membrane followed by 0.2 and 0.14 µm membranes. All selected membranes showed low rejection of sugars, with values lower than 10%, and no retention towards anthocyanins. All the clarified extracts showed a turbidity lower than 4.87 NTU. Based on the experimental results, the 0.14 µm membrane appeared as the best option for the clarification of grape marc extract.
36
Febriasari, Arifina, Huriya, Annisa Hasna Ananto, Meri Suhartini e Sutrasno Kartohardjono. "Polysulfone–Polyvinyl Pyrrolidone Blend Polymer Composite Membranes for Batik Industrial Wastewater Treatment". Membranes 11, n. 1 (18 gennaio 2021): 66. http://dx.doi.org/10.3390/membranes11010066.
Testo completoAbstract (sommario):
Batik wastewater, in general, is colored and has high concentrations of BOD (biological oxygen demand), COD (chemical oxygen demand), and dissolved and suspended solids. Polysulfone (PSf)-based membranes with the addition of polyvinyl pyrrolidone (PVP) were prepared to treat batik industrial wastewater. PSf/PVP membranes were prepared using the phase inversion method with N-methyl-2 pyrrolidone (NMP) as the solvent. Based on the membrane characterization through FESEM, water contact angle, porosity, and mechanical tests showed a phenomenon where the addition of PVP provided thermodynamic and kinetic effects on membrane formation, thereby affecting porosity, thickness, and hydrophilicity of the membranes. The study aims to observe the effect of adding PVP on polysulfone membrane permeability and antifouling performance on a laboratory scale through the ultrafiltration (UF) process. With the addition of PVP, the operational pressure of the polysulfone membrane was reduced compared to that without PVP. Based on the membrane filtration results, the highest removal efficiencies of COD, TDS (total dissolved solid), and conductivity achieved in the study were 80.4, 84.6, and 83.6%, respectively, on the PSf/PVP 0.35 membrane operated at 4 bar. Moreover, the highest color removal efficiency was 85.73% on the PSf/PVP 0.25 operated at 5 bar. The antifouling performance was identified by calculating the value of total, reversible, and irreversible membrane fouling, wherein in this study, the membrane with the best antifouling performance was PSf/PVP 0.25.
37
Sainiemi, Lauri, Kestas Grigoras e Sami Franssila. "Suspended nanostructured alumina membranes". Nanotechnology 20, n. 7 (23 gennaio 2009): 075306. http://dx.doi.org/10.1088/0957-4484/20/7/075306.
Testo completo
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Haronian, D., e N. C. MacDonald. "Spring suspended corrugated membranes". Journal of Micromechanics and Microengineering 5, n. 4 (1 dicembre 1995): 289–96. http://dx.doi.org/10.1088/0960-1317/5/4/005.
Testo completo
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Hakami, Mohammed Wali, Abdullah Alkhudhiri, Sirhan Al-Batty, Myrto-Panagiota Zacharof, Jon Maddy e Nidal Hilal. "Ceramic Microfiltration Membranes in Wastewater Treatment: Filtration Behavior, Fouling and Prevention". Membranes 10, n. 9 (22 settembre 2020): 248. http://dx.doi.org/10.3390/membranes10090248.
Testo completoAbstract (sommario):
Nowadays, integrated microfiltration (MF) membrane systems treatment is becoming widely popular due to its feasibility, process reliability, commercial availability, modularity, relative insensitivity in case of wastewater of various industrial sources as well as raw water treatment and lower operating costs. The well thought out, designed and implemented use of membranes can decrease capital cost, reduce chemical usage, and require little maintenance. Due to their resistance to extreme operating conditions and cleaning protocols, ceramic MF membranes are gradually becoming more employed in the drinking water and wastewater treatment industries when compared with organic and polymeric membranes. Regardless of their many advantages, during continuous operation these membranes are susceptible to a fouling process that can be detrimental for successful and continuous plant operations. Chemical and microbial agents including suspended particles, organic matter particulates, microorganisms and heavy metals mainly contribute to fouling, a complex multifactorial phenomenon. Several strategies, such as chemical cleaning protocols, turbulence promoters and backwashing with air or liquids are currently used in the industry, mainly focusing around early prevention and treatment, so that the separation efficiency of MF membranes will not decrease over time. Other strategies include combining coagulation with either inorganic or organic coagulants, with membrane treatment which can potentially enhance pollutants retention and reduce membrane fouling.
40
Pierkiel, A., e J. Lanting. "Membrane-coupled anaerobic digestion of municipal sewage sludge". Water Science and Technology 52, n. 1-2 (1 luglio 2005): 253–58. http://dx.doi.org/10.2166/wst.2005.0525.
Testo completoAbstract (sommario):
Membrane-coupled anaerobic digestion utilizes a concept of simultaneous sludge digestion and thickening. Membranes may successfully be applied to eliminate the need for thickening polymers and avoid their likely inhibitory effect on anaerobic biomass. A 550 L completely mixed anaerobic digester was operated under mesophilic conditions (35 °C). Two ultrafiltration membrane systems were evaluated for their potential in membrane-coupled anaerobic digestion: vibrating and cross flow. A volatile solids reduction of 59% was achieved at an average mixed liquor suspended solids concentration of 1.8%. The substrate utilization rate was 1.3 d−1. The vibrating membrane operated at a flux of 1.6–2.0 m3/m2-d and the tubular membrane fluxes in the range 3.4–3.6 m3/m2-d.
41
Batrinescu, Gheorghe, Roxana-Elena Scutariu, Nicolae-Ionut Cristea, Ioana-Alexandra Ionescu e Gheorghe Nechifor. "The Clogging Effect in the Process of Protein Separation by Ultrafiltration". Materiale Plastice 57, n. 3 (30 settembre 2020): 224–37. http://dx.doi.org/10.37358/mp.20.3.5395.
Testo completoAbstract (sommario):
In this study, five ultrafiltration membranes (polysulfone, cellulose acetate and polyethe-rsulfone) were tested in the treatment of aqueous protein solutions similar to wastewater from fermentation industries. The experiments were made in tangential flow filtration. The permeate flux for the five membranes tested at the optimum pressure of 3 bar decreased due to the effect of clogging the pores by the macromolecular protein solutions. Cellulose acetate membranes showed the lowest permeate flux (Ac-Cel1=152.4 L/m2.h and Ac-Cel2=40.3 L/m2.h) which doesn�t recommend them for the ultrafiltration process of bovine serum albumin. When a polysulfone membrane was used in several cycles of protein-containing wastewater ultrafiltration, the permeate flow decreased progressively from one cycle to another due to the internal clogging of the membrane (501.6 L/m2.h up to 444.0 L/m2.h). Regarding the ultrafiltration of protein solutions with a suspended yeast content, the clogging was predominant on the membrane�s surface, which results in a decrease of the permeate flux by over 50%.
42
Gubari, M. Q., N. V. Alexejewa e M. Y. Balabanova. "A combination of reverse osmosis and electrodialysis to improve water recovery in industrial wastewater". Proceedings of the Voronezh State University of Engineering Technologies 82, n. 4 (20 gennaio 2021): 227–35. http://dx.doi.org/10.20914/2310-1202-2020-4-227-235.
Testo completoAbstract (sommario):
The article discusses in detail the membrane processing of complex systems, reverse osmosis (RO) and electrodialysis (ED) membranes. Currently, the development of industrial wastewater treatment technologies is of great interest to many researchers. This is due to the fact that the food, pharmaceutical and chemical industries are becoming increasingly important in our lives, while exacerbating one of the most serious environmental problems, environmental pollution from industrial wastewater, which contains harmful substances in high concentrations. This study is devoted to the analysis of a new technology for the extraction of complex components from industrial wastewater, combining reverse osmosis and electrodialysis. Reverse osmosis systems are pressure controlled membrane separation processes. In contrast, an electrodialysis system is an electrochemical process that is commonly used industrially under normal atmospheric pressure. However, such membrane processes have a significant drawback, the working membranes are contaminated with suspended substances in the wastewater and lose their activity. Therefore, to maintain the activity of the membranes for a long time, it is necessary to pre-treat wastewater by removing suspended solids. The analysis of the recovered components opens up new perspectives for the recovery of industrial wastewater. There is a wide range of methods for pretreatment of water for reverse osmosis and electrodialysis. Ultrafiltration (UF) followed by reverse osmosis is an important process for separating organic and inorganic compounds from wastewater. This article discusses some of these methods. In conclusion, it should be noted that electrodialysis demonstrates remarkable technical advantages in the treatment of concentrated solution after RO.
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Mausolf, A., J. Jungmann, H. Robenek e P. Prehm. "Shedding of hyaluronate synthase from streptococci". Biochemical Journal 267, n. 1 (1 aprile 1990): 191–96. http://dx.doi.org/10.1042/bj2670191.
Testo completoAbstract (sommario):
Hyaluronate synthase was shed into the culture medium from growing streptococci (group C) together with nascent hyaluronate. The mechanism of solubilization was analysed using isolated protoplast membranes. Solubilization increased when membranes were suspended in larger volumes, but it was temperature-independent and was not inhibited by protease inhibitors. Increased hyaluronate chain length enhanced solubilization. The soluble synthase could re-integrate into Streptococcal membranes in a saturable manner. The soluble synthase behaved like an integral membrane protein, although it was not integrated into phospholipid vesicles. In sucrose velocity centrifugation the synthase had a higher sedimentation rate in detergent-free solution, indicating that it existed in an aggregated state.
44
Takizawa, S., P. Zhao, S. Ohgaki e H. Katayama. "Kinetic analysis of PAC cake-layer formation in hybrid PAC-MF systems". Water Supply 8, n. 1 (1 aprile 2008): 1–7. http://dx.doi.org/10.2166/ws.2008.006.
Testo completoAbstract (sommario):
Experimental studies were conducted to evaluate the effectiveness of backwashing and air-scouring to prevent cake-layer formation on the membranes in a hybrid PAC-MF process. The membrane filtration chamber used in this study was separated into two zones; namely, the PAC adsorption zone (PAZ) and the membrane filtration zone (MFZ). In MFZ tubular ceramic membranes were installed, and powdered activated carbon (PAC) was suspended in PAZ at a concentration of 20 g/L by aeration. Air-scouring and backwashing rates were gradually increased to see if these physical cleaning measures can reduce or maintain the filtration resistance due to formation of PAC cake layer on the membrane. Two types of saw-dust PAC having different sizes were used to find the difference of the effects of air-scouring and backwashing. A smaller PAC (Shirasagi C1, Japan EnviroChemicals, Co.) showed a slower increasing rate of filtration resistance than the larger PAC (Shirasagi S-10, Japan EnviroChemicals, Co.). It was found that air-scouring didn't reduce the rate of cake fouling formation of PAC S-10, but can quite effectively reduce the rate of PAC C-1 attachment to the membrane. On the contrary, backwashing was not effective for PAC C-1, but quite effective for PAC S-10. PAC C1 formed a porous cake with low specific resistance, which can be easily removed by air-scouring, but cannot be removed by backwashing. On the other hand, PAC S-10 formed a tight cake layer because suspended particles get in to the void space between the PAC S-10. A dynamic model was proposed to explain the effect of air-scouring and backwashing to removal cake layer from the membranes.
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Ahmad, Norhayati, Nakamura Yuzo, Hiroki Kamibayasi e Maisarah Mohamed Bazin. "Study on Fabrication of Ceramic Membrane from Shirasu Balloon for Waste Water Filtration". Advanced Materials Research 686 (aprile 2013): 305–10. http://dx.doi.org/10.4028/www.scientific.net/amr.686.305.
Testo completoAbstract (sommario):
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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Brennan, Brian, Ciprian Briciu-Burghina, Sean Hickey, Thomas Abadie, Sultan M. al Ma Awali, Yan Delaure, John Durkan et al. "Pilot Scale Study: First Demonstration of Hydrophobic Membranes for the Removal of Ammonia Molecules from Rendering Condensate Wastewater". International Journal of Molecular Sciences 21, n. 11 (30 maggio 2020): 3914. http://dx.doi.org/10.3390/ijms21113914.
Testo completoAbstract (sommario):
Hydrophobic membrane contactors represent a promising solution to the problem of recycling ammoniacal nitrogen (N-NH4) molecules from waste, water or wastewater resources. The process has been shown to work best with wastewater streams that present high N-NH4 concentrations, low buffering capacities and low total suspended solids. The removal of N-NH4 from rendering condensate, produced during heat treatment of waste animal tissue, was assessed in this research using a hydrophobic membrane contactor. This study investigates how the molecular composition of rendering condensate wastewater undergo changes in its chemistry in order to achieve suitability to be treated using hydrophobic membranes and form a suitable product. The main objective was to test the ammonia stripping technology using two types of hydrophobic membrane materials, polypropylene (PP) and polytetrafluoroethylene (PTFE) at pilot scale and carry out: (i) Process modification for NH3 molecule removal and (ii) product characterization from the process. The results demonstrate that PP membranes are not compatible with the condensate waste as it caused wetting. The PTFE membranes showed potential and had a longer lifetime than the PP membranes and removed up to 64% of NH3 molecules from the condensate waste. The product formed contained a 30% concentrated ammonium sulphate salt which has a potential application as a fertilizer. This is the first demonstration of hydrophobic membrane contactors for treatment of condensate wastewater.
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Thompson, M. A. "Membrane filtration of high turbidity sources". Water Supply 1, n. 5-6 (1 giugno 2001): 325–30. http://dx.doi.org/10.2166/ws.2001.0129.
Testo completoAbstract (sommario):
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.
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Yuliawati, Erna, e Ahmad Fauzi Ismail. "Submerged Ultrafiltration for Minimizing Energy Process of Refinery Wastewater Treatment". Advanced Materials Research 789 (settembre 2013): 531–37. http://dx.doi.org/10.4028/www.scientific.net/amr.789.531.
Testo completoAbstract (sommario):
Refinery wastewater treatment is needed especially in the oil-producing arid regions such as oil refineries due to water scarcity. One of potentially applicable process to treat refinery wastewater is a submerged membrane technology. However, the application of submerged membrane systems for industrial wastewater treatment is still in its infancy due to significant variety in wastewater composition and high operational costs. Aim of this study was to investigate ultrafiltration (UF) membrane morphology and performance for refinery produced wastewater treatment. Submerged UF bundle was equipped using polyvinylidene fluoride (PVDF) hollow fibers, which added by dispersing lithium chloride monohydrate (LiCl.H2O) and titanium dioxide (TiO2). The comparison of morphological and performance tests was conducted on prepared PVDF ultrafiltration membranes. Distinctive changes were observed in membrane characteristics in term of membrane wettability, tensile testing and roughness measurement. Mean pore size and surface porosity were calculated based on permeate flux. Fouling characteristics for hydrophilic PVDF hollow fibers fouled with suspended solid matter was also investigated. Mixed liquor suspended solid (MLSS) of 3 g/L and 4.5 g/L were assessed by using submerged PVDF membrane with varied air bubble flow rates. Results showed that effect of air bubbles flow rate of 2.4 ml/min increased flux, total suspended solids (TSS) and sulfide removal of 148.82 L/m2h, 99.82 % and 89.2%, respectively due to increase of turbulence around fibers, which exerts shear stress to minimize particles deposited on membrane surface. It was concluded that submerged ultrafiltration is an available option to minimize energy process for treating such wastewater solution.
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Vasic, Vesna, Marina Sciban, Aleksandar Jokic, Jelena Prodanovic e Dragana Kukic. "Microfiltration of distillery stillage: Influence of membrane pore size". Acta Periodica Technologica, n. 43 (2012): 217–24. http://dx.doi.org/10.2298/apt1243217v.
Testo completoAbstract (sommario):
Stillage is one of the most polluted waste products of the food industry. Beside large volume, the stillage contains high amount of suspended solids, high values of chemical oxygen demand and biological oxygen demand, so it should not be discharged in the nature before previous purification. In this work, three ceramic membranes for microfiltration with different pore sizes were tested for stillage purification in order to find the most suitable membrane for the filtration process. Ceramic membranes with a nominal pore size of 200 nm, 450 nm and 800 nm were used for filtration. The influence of pore size on permeate flux and removal efficiency was investigated. A membrane with the pore size of 200 nm showed the best filtration performance so it was chosen for the microfiltration process.
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Conidi, Carmela, Enrico Drioli e Alfredo Cassano. "Coupling Ultrafiltration-Based Processes to Concentrate Phenolic Compounds from Aqueous Goji Berry Extracts". Molecules 25, n. 16 (18 agosto 2020): 3761. http://dx.doi.org/10.3390/molecules25163761.
Testo completoAbstract (sommario):
In this work, a membrane-based process for the purification and concentration of antioxidant compounds from aqueous Goji (Lycium barbarum L.) berry extracts was investigated. The aqueous extract was previously clarified with hollow fiber ultrafiltration (UF) membranes in order to remove suspended solids and β-carotene and to produce a clarified extract enriched in phenolic compounds. Then, three UF flat sheet polyamide membranes with a molecular weight cut-off (MWCO) in the range 1000–3500 Da were tested to purify and concentrate phenolic compounds from the clarified extract. The effect of MWCO and transmembrane pressure (TMP) on the performance of selected membranes in terms of productivity and selectivity towards total dissolved solids (TDS), total phenolic compounds (TPC), total carbohydrates (TC) and total antioxidant activity (TAA) was evaluated. Experimental results indicated that the 2500 Da membrane exhibited a lower fouling index, higher cleaning efficiency, lower rejection towards carbohydrates (lower than 30%) and higher rejection towards phenolic compounds (higher than 50%) in comparison to the other investigated membranes. The inclusion of a diafiltration process in the treatment of the clarified extract with this membrane in a spiral-wound configuration improved the concentration of sugar compounds in the permeate stream and increased the purification of phenolic compounds in the retentate fraction.