Littérature scientifique sur le sujet « Fouling precursors »
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Articles de revues sur le sujet "Fouling precursors"
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Shetty, Nitin, Marappagounder Ramasamy, and Rajashekhar Pendyala. "Effect of Bulk Temperature on Formation of Crude Oil Fouling Precursors on Heat Transfer Surfaces." Applied Mechanics and Materials 625 (September 2014): 482–85. http://dx.doi.org/10.4028/www.scientific.net/amm.625.482.
Texte intégralRésumé :
Temperature plays a very important role in the formation of fouling precursors in crude oils which is considered to be the first step before the precursors are either attached to the wall as a deposit or transferred back to the bulk fluid by diffusion. In order to investigate the formation characteristics of fouling precursors in crude oils at different bulk temperatures, a custom-design thin film microreactor is constructed. It is observed during the experiments that tendency to form fouling precursors is higher at higher surface temperatures. The precursor particles once formed continue to grow in size with time at constant surface temperatures. It is also observed that the particles tend to grow in size while it is cooled when the temperatures are below 55 oC.
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Wray, Heather E., Robert C. Andrews, and Pierre R. Bérubé. "Coagulation optimization for DOC removal: pilot-scale analysis of UF fouling and disinfection byproduct formation potential." Water Supply 16, no. 2 (2015): 473–80. http://dx.doi.org/10.2166/ws.2015.157.
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A pilot-scale study was performed to evaluate a coagulant dose which had been optimized for biopolymer (i.e., foulant) removal on subsequent ultrafiltration (UF) fouling, as well as disinfection by-product (DBP) precursor removal. Polyaluminum chloride (PACl) dosages were selected based on a point of diminishing returns for biopolymer removal (0.5 mg/L) and directly compared to that applied at full-scale (6 mg/L). Membrane fouling (reversible and irreversible) was measured as resistance increase over a 48 hour filtration period. DBP formation potential (total trihalomethanes (TTHMs), haloacetic acids (HAA9) and total adsorbable organic halides (AOX)) were measured in both raw and treated waters. Results of the study indicate that application of a PACl dose optimized for biopolymer reduction (0.5 mg/L) resulted in 65% less irreversible UF fouling when compared to 6 mg/L. The addition of PACl prior to the membrane resulted in up to a 14% reduction in DBP precursors relative to the UF membrane alone. A similar level of DBP precursor reduction was achieved for both 0.5 and 6 mg/L dosages. The results have implications for cost savings, which may be realized due to decreased chemical use, as well as increased membrane life associated with lower irreversible fouling rates.
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Ramasamy, M., and Umesh B. Deshannavar. "Effect of Bulk Temperature and Heating Regime on Crude Oil Fouling: An Analysis." Advanced Materials Research 917 (June 2014): 189–98. http://dx.doi.org/10.4028/www.scientific.net/amr.917.189.
Texte intégralRésumé :
Semi-empirical threshold fouling models predict higher fouling rates at high surface or film temperatures. Several experimental fouling data reported in literature and from our study were analyzed with respect to increase in surface and bulk temperatures that showed a decrease in fouling rates. The existing threshold fouling models do not adequately describe the phenomenon of decreasing fouling rates with increase in surface or bulk temperatures. The possible causes including the effect of temperature difference, heating regime and solubility of fouling precursors were analyzed and reported.
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Takeuchi, Haruka, Naoyuki Yamashita, Norihide Nakada, and Hiroaki Tanaka. "Removal Characteristics of N-Nitrosamines and Their Precursors by Pilot-Scale Integrated Membrane Systems for Water Reuse." International Journal of Environmental Research and Public Health 15, no. 9 (2018): 1960. http://dx.doi.org/10.3390/ijerph15091960.
Texte intégralRésumé :
This study investigated the removal characteristics of N-Nitrosamines and their precursors at three pilot-scale water reclamation plants. These plants applies different integrated membrane systems: (1) microfiltration (MF)/nanofiltration (NF)/reverse osmosis (RO) membrane; (2) sand filtration/three-stage RO; and (3) ultrafiltration (UF)/NF and UF/RO. Variable removal of N-Nitrosodimethylamine (NDMA) by the RO processes could be attributed to membrane fouling and the feed water temperature. The effect of membrane fouling on N-Nitrosamine removal was extensively evaluated at one of the plants by conducting one month of operation and chemical cleaning of the RO element. Membrane fouling enhanced N-Nitrosamine removal by the pilot-scale RO process. This finding contributes to better understanding of the variable removal of NDMA by RO processes. This study also investigated the removal characteristics of N-Nitrosamine precursors. The NF and RO processes greatly reduced NDMA formation potential (FP), but the UF process had little effect. The contributions of MF, NF, and RO processes for reducing FPs of NDMA, N-Nitrosopyrrolidine and N-Nitrosodiethylamine were different, suggesting different size distributions of their precursors.
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Azzeh, Jamal, Lizbeth Taylor-Edmonds, and Robert C. Andrews. "Engineered biofiltration for ultrafiltration fouling mitigation and disinfection by-product precursor control." Water Supply 15, no. 1 (2014): 124–33. http://dx.doi.org/10.2166/ws.2014.091.
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A pilot-scale study was conducted to evaluate the impact of several biofiltration enhancement strategies in terms of organic removal to reduce disinfection by-product (DBP) formation potential and mitigate ultrafiltration (UF) fouling. Strategies included nutrient addition (nitrogen and phosphorus) to optimize metabolic degradation of organics, use of hydrogen peroxide (H2O2, peroxide) to improve filter run times, and the application of in-line aluminum sulphate (alum) for biopolymer removal. The impact of media type on performance was also examined (anthracite versus granular activated carbon (GAC)). Passive biofiltration (without enhancement) reduced dissolved organic carbon (∼5%), biopolymers (∼20%), and trihalomethane and haloacetic acid precursors (∼20% and ∼12%, respectively) while mitigating UF irreversible fouling (∼60%). Nutrient addition was not observed to enhance biological performance. Addition of 0.5 mg/L hydrogen peroxide decreased head loss by up to 45% without affecting organic removal; however at a dosage of 1 mg/L, it negatively impacted both UF fouling and DBP precursor removal. In-line alum addition prior to biofiltration (<0.5 mg/L) improved UF fouling control by up to 40%, without sacrificing head loss. Overall, GAC provided superior performance when compared to anthracite.
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Millanar-Marfa, Jessa, Laura Borea, Mark de Luna, Florencio Ballesteros, Vincenzo Belgiorno, and Vincenzo Naddeo. "Fouling Mitigation and Wastewater Treatment Enhancement through the Application of an Electro Moving Bed Membrane Bioreactor (eMB-MBR)." Membranes 8, no. 4 (2018): 116. http://dx.doi.org/10.3390/membranes8040116.
Texte intégralRésumé :
High operational cost due to membrane fouling propensity remains a major drawback for the widespread application of membrane bioreactor (MBR) technology. As a result, studies on membrane fouling mitigation through the application of integrated processes have been widely explored. In this work, the combined application of electrochemical processes and moving bed biofilm reactor (MBBR) technology within an MBR at laboratory scale was performed by applying an intermittent voltage of 3 V/cm to a reactor filled with 30% carriers. The treatment efficiency of the electro moving bed membrane bioreactor (eMB-MBR) technology in terms of ammonium nitrogen (NH4-N) and orthophosphate (PO4-P) removal significantly improved from 49.8% and 76.7% in the moving bed membrane bioreactor (MB-MBR) control system to 55% and 98.7% in the eMB-MBR, respectively. Additionally, concentrations of known fouling precursors and membrane fouling rate were noticeably lower in the eMB-MBR system as compared to the control system. Hence, this study successfully demonstrated an innovative and effective technology (i.e., eMB-MBR) to improve MBR performance in terms of both conventional contaminant removal and fouling mitigation.
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Jamieson, Tamar, Harriet Whiley, Jason R. Gascooke, and Sophie C. Leterme. "Can Aggregate-Associated Organisms Influence the Fouling in a SWRO Desalination Plant?" Microorganisms 10, no. 4 (2022): 682. http://dx.doi.org/10.3390/microorganisms10040682.
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This pilot study investigates the formation of aggregates within a desalination plant, before and after pre-treatment, as well as their potential impact on fouling. The objective is to provide an understanding of the biofouling potential of the feed water within a seawater reverse osmosis (SWRO) desalination plant, due to the limited removal of fouling precursors. The 16S and 18S rRNA was extracted from the water samples, and the aggregates and sequenced. Pre-treatment systems, within the plant remove < 5 µm precursors and organisms; however, smaller size particles progress through the plant, allowing for the formation of aggregates. These become hot spots for microbes, due to their nutrient gradients, facilitating the formation of niche environments, supporting the proliferation of those organisms. Aggregate-associated organisms are consistent with those identified on fouled SWRO membranes. This study examines, for the first time, the factors supporting the formation of aggregates within a desalination system, as well as their microbial communities and biofouling potential.
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Bu, Fan, Baoyu Gao, Qinyan Yue, Caiyu Liu, Wenyu Wang, and Xue Shen. "The Combination of Coagulation and Adsorption for Controlling Ultra-Filtration Membrane Fouling in Water Treatment." Water 11, no. 1 (2019): 90. http://dx.doi.org/10.3390/w11010090.
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Ultra-filtration technology has been increasingly used in drinking water treatment due to improvements in membrane performance and lowering of costs. However, membrane fouling is the main limitation in the application of ultra-filtration technology. In this study, we investigated the impact of four different pre-treatments: Coagulation, adsorption, coagulation followed by adsorption (C-A), and simultaneous coagulation and adsorption (C+A), on membrane fouling and natural organic matter removal efficiency. The results showed that adsorption process required a large amount of adsorbent and formed a dense cake layer on the membrane surface leading to severe membrane fouling. Compared to adsorption alone, the coagulation and C-A processes decreased the transmembrane pressure by 4.9 kPa. It was due to less accumulation of particles on the membrane surface. As for water quality, the C-A ultra-filtration process achieved the highest removal efficiencies of natural organic matter and disinfection by-product precursors. Therefore, the addition of adsorbent after coagulation is a potentially important approach for alleviating ultra-filtration membrane fouling and enhancing treatment performance.
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Davies, S. H., M. J. Baumann, S. Byun, L. M. Corneal, V. V. Tarabara, and S. J. Masten. "Fabrication of catalytic ceramic membranes for water filtration." Water Supply 10, no. 1 (2010): 81–86. http://dx.doi.org/10.2166/ws.2010.789.
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The paper describes the use of the layer-by-layer technique to coat ceramic membranes with iron and manganese oxide nanoparticles. The coatings are thin (&lt;50 nm) and relatively uniform. These coatings enhance the performance of the hybrid ozonation-filtration process. With the coated membranes it is possible to significantly reduce fouling, improve the removal of DBP precursors and more effectively kill Escherichia coli bacteria.
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Sfameni, Silvia, Giulia Rando, Maurilio Galletta, et al. "Design and Development of Fluorinated and Biocide-Free Sol–Gel Based Hybrid Functional Coatings for Anti-Biofouling/Foul-Release Activity." Gels 8, no. 9 (2022): 538. http://dx.doi.org/10.3390/gels8090538.
Texte intégralRésumé :
Biofouling has destructive effects on shipping and leisure vessels, thus producing severe problems for marine and naval sectors due to corrosion with consequent elevated fuel consumption and higher maintenance costs. The development of anti-fouling or fouling release coatings creates deterrent surfaces that prevent the initial settlement of microorganisms. In this regard, new silica-based materials were prepared using two alkoxysilane cross-linkers containing epoxy and amine groups (i.e., 3-Glycidyloxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane, respectively), in combination with two functional fluoro-silane (i.e., 3,3,3-trifluoropropyl-trimethoxysilane and glycidyl-2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononylether) featuring well-known hydro repellent and anti-corrosion properties. As a matter of fact, the co-condensation of alkoxysilane featuring epoxide and amine ends, also mixed with two opportune long chain and short chain perfluorosilane precursors, allows getting stable amphiphilic, non-toxic, fouling release coatings. The sol–gel mixtures on coated glass slides were fully characterized by FT-IR spectroscopy, while the morphology was studied by scanning electron microscopy (SEM), and atomic force microscopy (AFM). The fouling release properties were evaluated through tests on treated glass slides in different microbial suspensions in seawater-based mediums and in seawater natural microcosms. The developed fluorinated coatings show suitable antimicrobial activities and low adhesive properties; no biocidal effects were observed for the microorganisms (bacteria).
Thèses sur le sujet "Fouling precursors"
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Borea, Laura. "Advanced MBR processes for wastewater treatment and energy production." Doctoral thesis, Universita degli studi di Salerno, 2016. http://hdl.handle.net/10556/2491.
Texte intégralRésumé :
2014 - 2015<br>More stringent standards on water quality along with the shortage of vater resources have led to the development of advanced wastewater treatment processes, in order to ensure the respect of discharge limits and the reuse of trated water... [edited by author]<br>XIV n.s.
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Li, Xu. "Transparent exopolymer particles (TEP) and their precursors in reverse osmosis (RO) systems: quantification, fouling potential and cleaning." Thesis, Li, Xu (2018) Transparent exopolymer particles (TEP) and their precursors in reverse osmosis (RO) systems: quantification, fouling potential and cleaning. PhD thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/45248/.
Texte intégralRésumé :
Transparent exopolymer particles (TEP) and their precursors have been identified as critical causal factors in fouling of desalination and other water treatment membranes. TEP and the fractions thereof are composed of a wide variety of organic constituents and size fractions and have conventionally been only quantified by an operational method, specifically, Alcian Blue measurement. For fouling control and mitigation purposes, it is important to accurately measure the amount of both TEP and TEP precursors, their fouling capacity, and their response to cleaning. However, these issues are not well understood nor are there generally accepted methods for undertaking comparative studies to address this lack of understanding. In this study, a three-stage research study was undertaken to evaluate (1) TEP and TEP precursors quantification methods, (2) TEP and TEP precursors fouling potential on seawater reverse osmosis (SWRO) membranes, and (3) hydrogen peroxide (H2O2) cleaning performance on TEP fouled SWRO membranes. It was found that the concentrations of TEP may only represent ~10% of the total mass; while TEP precursors represent ~80% of the total TEP. This highlights the importance of measuring, reporting, and operationally considering both TEP and TEP precursors for membrane biofouling studies. A reliable, adaptable statistical method using the T-test was developed to quantify and develop a criterion for differentiating fouling behaviour of different TEP surrogates and TEP fractions. Similar fouling potential was measured with total TEP, TEP, and TEP precursors at the same concentrations. Therefore, TEP concentrations rather than TEP sizes were correlated to membrane fouling. It highlighted the importance of developing new advanced pre-treatment techniques for TEP precursors removal. H2O2 cleaning enhanced water flux, possibly due to re-compaction/re-attachment of xanthan gum on the membrane surface following its breakdown into smaller fragments. The hypothesis of membrane degradation due to exposure to H2O2 during cycles of fouling and cleaning-in-place (CIP) was not supported by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), salt flux, and salt rejection results. The work strongly suggests peroxide cleaning be further evaluated with field trials as an alternative to commonly used, but more destructive, cleaning techniques.
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Lee, Hsin-Hua, and 李欣樺. "Study on the Effects of DBP Precursors on Fouling Electric Enhanced Membranes." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/69028489851217465635.
Texte intégralRésumé :
碩士<br>國立臺灣大學<br>環境工程學研究所<br>92<br>The effect of humic acid size distribution as electric enhanced membrane process under various membrane pressure and electric voltage was investigated. Humic acid solution was divided into three groups, namely G1-25,000~3,000 Da, G2-3,000~500 Da and G3-500〜50 Da, by means of gel filtration chromatography according to their apparent molecular weight. Ultrafiltration behaviors were analyzed by the resistance-in-series model.
The results showed that flux declined to the extend of initial flux 85%, 78% and 72% with pressure under 47 kPa, 74 kPa and 98 kPa, respectively. Resistance in series model also revealed that irreversible resistance raised from 6 % to 21%. Besides, humic acid removal efficiency decreased with pressure increase.
While treating various molecular size solution at pressure 98 kPa. The order of flux decline was G3> G2 >G1≒ unfractionated solution. It was believed that smaller solute with stronger adsorption to the membrane pores caused serious membrane fouling and flux decline. Smaller molecular could easily pass through 100k Da membrane, thus UV254 and DOC removal efficiency was only 70 % and 47 %, respectively. However, the reversible and weak reversible resistance of the smaller molecule was 33 %, which was higher than 12 % of G1 group. Thus, frequent backwash was a promising way to deal with smaller solute.
When operating the electric enhanced membrane process, electrophoresis and electroosmosis are the main mechanism to enhance the filtration process. Adding 25 V to the system could keep the flux greater than 80 % of initial flux without electric enhanced. Besides, it has capability to reduce NOM precursors containing in permeate. As a result, the electrical enhanced membrane process has the potential for drinking water treatment.
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Azzeh, Jamal. "Engineered Biofiltration for Ultrafiltration Fouling Control and DBP Precursor Removal." Thesis, 2014. http://hdl.handle.net/1807/65534.
Texte intégralRésumé :
Recently, treatment plants have adopted biofiltration to compliment conventional treatment and ozonation. Previous literature has focused on passive applications of biofiltration. In this study, several pilot-scale biofiltration trains were designed in parallel to conventional treatment to investigate the impact of nutrient addition (nitrogen and phosphorus), use of hydrogen peroxide, aluminum sulphate (alum), and different filtration media (anthracite vs. granular activated carbon (GAC)) on biofiltration performance. Parameters measured included organic removal, reduction of DBP precursor, improvements in filter runtimes and ultrafiltration (UF) fouling control. Nutrient addition did not improve biofiltration performance. Supplementing hydrogen peroxide (<1 mg/L) decreased headloss, DBP formation potentials while adversely affecting UF fouling. In-line alum addition (<0.5 mg/L) improved biofilter’s ability to control fouling and DBP precursor without adversely impacting headloss. GAC provided superior performance when compared to anthracite. Conventional treatment provided higher DOC, and DBP precursor removal, as well as better UF fouling control compared to biofiltration.
Chapitres de livres sur le sujet "Fouling precursors"
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Holberg, Stefan. "Non-Hydrolyzed Resins for Organic-Inorganic Hybrid Coatings." In Materials Science and Engineering. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-1798-6.ch030.
Texte intégralRésumé :
This chapter focuses on resins based on non-hydrolyzed, monomeric and polymeric alkoxysilanes. As alternative to classical sol-gel processing, the resins are applied to a surface without a preceding hydrolysis step. Only after application, hydrolysis and condensation of the alkoxysilyl groups occur by means of atmospheric moisture to result cross-linked organic-inorganic hybrid coatings. While the use of non-hydrolyzed silanes is well established, for example by applying polyethyl silicate as binder for zinc-rich anti-corrosive primers, this chapter describes the chemical structures of various novel organic-inorganic hybrid precursors that have significantly extended the area of application to adhesives and scratch-resistant, repellent, or anti-fouling coatings. At present, individual resins are produced and applied at industrial scale in the fields of protective coatings and automotive topcoats.
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Holberg, Stefan. "Non-Hydrolyzed Resins for Organic-Inorganic Hybrid Coatings." In Research Perspectives on Functional Micro- and Nanoscale Coatings. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-5225-0066-7.ch005.
Texte intégralRésumé :
This chapter focuses on resins based on non-hydrolyzed, monomeric and polymeric alkoxysilanes. As alternative to classical sol-gel processing, the resins are applied to a surface without a preceding hydrolysis step. Only after application, hydrolysis and condensation of the alkoxysilyl groups occur by means of atmospheric moisture to result cross-linked organic-inorganic hybrid coatings. While the use of non-hydrolyzed silanes is well established, for example by applying polyethyl silicate as binder for zinc-rich anti-corrosive primers, this chapter describes the chemical structures of various novel organic-inorganic hybrid precursors that have significantly extended the area of application to adhesives and scratch-resistant, repellent, or anti-fouling coatings. At present, individual resins are produced and applied at industrial scale in the fields of protective coatings and automotive topcoats.
Actes de conférences sur le sujet "Fouling precursors"
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Corsini, Alessandro, and Cecilia Tortora. "Fouling Detection in Low Speed Fan Using Near-Field DIY Sound Pressure Sensors." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57557.
Texte intégralRésumé :
This work investigates the dynamics of rotating stall of a low speed axial fan in presence of fouling on the blades. Rotating stall is an aerodynamic issue of recognized importance in turbomachinery. The combination of rotating stall and presence of particles of dust and dirt from the surrounding environment, may lead to further issues in terms of performance, stall limit and blades life. In this paper the identification of the rotating stall pattern is carried out using time-resolved sound measurements in the far field region by means of a condenser microphone. The experimental tests are carried out with various geometries of fouling in order to evaluate the system ability to detect acoustically fouling and rotating stall. The results have been validated against state of the art techniques described in the literature. The acquired signals have been analysed using frequency domain analysis, and time domain analysis using a phase space reconstruction inspired technique. Both of the approaches demonstrate a modification of the stall dynamics in the low speed fan and allow the identification of diverse stall precursors and fouling presence.