Tesi sul tema "Reverse osmosis"
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1
Hassinger, Elaine. "Reverse Osmosis Units". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1994. http://hdl.handle.net/10150/156939.
Testo completoAbstract (sommario):
1 pp.Reverse osmosis (RO) is an excellent way to remove certain unwanted contaminants, such as lead and nitrates, from your drinking water. This article discusses how reverse osmosis works, and both the advantages and disadvantages of the system.
2
Arnaud, Damien. "Biofouling on reverse osmosis membranes". Thesis, Arnaud, Damien (2015) Biofouling on reverse osmosis membranes. Honours thesis, Murdoch University, 2015. https://researchrepository.murdoch.edu.au/id/eprint/29838/.
Testo completoAbstract (sommario):
Membrane biofouling is a major concern in water treatment processes as it can significantly reduce the system’s efficiency. Biofouling is mainly caused by microorganisms, and is difficult to control or avoid. It leads to higher operating pressure which strains the membrane, shortens the membrane life, and increases maintenance costs.
Multiple literature reviews suggest that the main contributors to membrane biofouling are polysaccharides. This is why in this project two model polysaccharides (alginate and xanthan) were used to study their individual fouling effects on reverse osmosis efficiency, as well as their fouling effects coupled with calcium chloride on the same system’s efficiency. During experiments, the polysaccharides were used in 0.2g/L concentrations, while calcium chloride was used at a concentration of 1.3mM. Because alginate and xanthan are two different types of polysaccharides, they would be expected to have different physical and chemical properties and thus have different fouling behaviours.
It was found that the polysaccharides did not have much effect on the system’s efficiency in the absence of calcium chloride. In experiments where calcium chloride was added in the feed solution with the polysaccharide, it was demonstrated that the addition of salt led to increased membrane fouling and greater decreases in system efficiency.
The fouled membranes were kept for confocal laser scanning microscopy of the fouling layers. The images determined the general structure of the cake formed on the membrane. Using the Imaris software, calculations on the average volume the cake layer was occupying (bio-volume) and the average compactness of the cake layer could be done.
During experiments, the membrane showed good salt rejections with over 96% salt rejection for each experiment
3
Zaghy, Amar. "Biofouling in reverse osmosis processes". Thesis, Zaghy, Amar (2016) Biofouling in reverse osmosis processes. Honours thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/33970/.
Testo completoAbstract (sommario):
Reverse Osmosis (RO) is a water purification technology that uses a semi-permeable membrane to remove salt and other particles from drinking water. It is the dominant technology which has overtaken many conventional systems in recent years. Membrane biofouling is the main disadvantage of using RO technology which can result in reducing the system’s efficiency. The rejected microorganisms on the surface of the membrane form a fouling layer (biofouling) which leads to a decline in permeate flux, increase of hydraulic resistance, increase in operating pressure, and shortening of the membrane life. Polysaccharides, produced by microorganisms, are the main substances responsible for membrane biofouling. In this study, two types of polysaccharides (alginate and pullulan) were used to investigate their individual fouling effects as well as their fouling effects coupled with sodium chloride and calcium chloride. 50 mM of ionic strength (27.5 g NaCl + 1.47 g CaCl2) and 0.2 g/L of polysaccharides were used in the fouling experiments conducted with a laboratory-scale reverse osmosis system.
It was found that alginate lead to more reduction in system’s efficiency in comparison with pullulan. The effect of alginate on the efficiency of the system was much more severe in the presence of salt, namely sodium chloride and calcium chloride, compared to its individual effect in the absence of salt. The addition of salt led to an increase in membrane fouling and a decrease in system’s efficiency. On the other hand, it was found that pullulan enhanced the system’s efficiency when it is combined with salt.
To support the above findings, a Confocal Laser Scanning Microscopy (CLSM) analysis, a Total Organic Carbon (TOC) test, and an estimation of the weight of produced fouling layers were performed. In general, analysing the results of the tests supported the findings.
4
Maskan, Fazilet Chemical Engineering & Industrial Chemistry UNSW. "Optimization of reverse osmosis membrane networks". Awarded by:University of New South Wales. Chemical Engineering and Industrial Chemistry, 2000. http://handle.unsw.edu.au/1959.4/18790.
Testo completoAbstract (sommario):
The optimization of a reverse osmosis (RO) system includes optimization of the design of the individual membrane modules, the system structure and the operating conditions of the system. Most previous studies considered either the optimal design of individual modules only or optimization of system structure and operating conditions for fixed module dimensions. This thesis developed a method to simultaneously optimize the module dimensions, system structure and operating conditions. The method comprised rules for generating a general superstructure for an RO system given the number of modules along with rules for generating technically and mathematically feasible sub-structures. The superstructure was based on maximum connectivity between unit operations. A connectivity matrix was used to represent the superstructure. The matrix was useful for checking sub-structure's feasibility and deriving a model for the sub-structure's optimization, comprising the minimum number of variables and constraints which minimized computational time and increased accuracy. For optimization, a nonlinear objective function of the annualized profit of the RO system was formulated, consisting of the revenue obtained from permeate sales, capital costs of the unit operations and operating costs for the system. It was found that RO system optimization is a nonconvex optimization problem. The most effective optimization procedure involved a combination of evolutionary computation, which was good for locating the global optimum, and a gradient-based method, which was superior in finding the exact optimum. Small population size, adaptive mutation rate and steady state replacement were the most efficient parameter settings for the evolutionary computation. Optimal design of two-stage RO systems with and without energy recovery, bypass and recycle streams was studied. Dimensions of predicted optimal modules approached those of current commercial modules but with much shorter feed channels. The mathematical optimum also had higher operating pressures. The optimum system structure was a series arrangement with different module dimensions in each stage. A sensitivity analysis showed that trends in the optimal design were similar when unit costs changed. An investigation of the scalability of the method for a three-stage RO system revealed several weaknesses. These are probably surmountable with the addition of more RO system specific knowledge.
5
Cohen, Ruben David. "Colloidal fouling of reverse osmosis membranes". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15308.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 128-133.
by Ruben David Cohen.
Ph.D.
6
Ding, Minxia. "Molecular simulations of reverse osmosis membranes". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S058/document.
Testo completoAbstract (sommario):
L'osmose inverse (OI) est actuellement le procédé le plus utilisé mondialement pour le dessalement des eaux saumâtres et de l’eau de mer. Cette thèse s'est intéressée à la simulation moléculaire de membranes d'OI afin d'améliorer la compréhension des propriétés structurales, dynamiques et de transport de l'eau et d'ions à l'intérieur de ces matériaux. La membrane d'OI étudiée dans ce travail est une membrane de polyamide aromatique, matériau le plus utilisé actuellement en OI. Dans la première partie de ce travail, une méthodologie a été développée pour construire un modèle atomique en trois dimensions d'une membrane polyamide fortement réticulé. Des simulations de dynamique moléculaire à l’équilibre (EMD) et hors-équilibre (NEMD) ont été réalisées pour étudier le comportement de l'eau et des ions Na+ et Cl- à travers la membrane. Les simulations EMD ont montré que les caractéristiques structurales de la membrane modèle étaient en bon accord avec celles d'une membrane typique d'OI. Les propriétés dynamiques et diélectriques de l'eau confinée dans la membrane ont également été étudiées et il a été montré que celles-ci étaient fortement modifiées par rapport à une phase volumique. Deux types de techniques NEMD ont été utilisés pour étudier le transport baromembranaire à travers la membrane modèle. La perméabilité à l'eau pure a été trouvée en très bon accord avec les données expérimentales rapportées dans la littérature et les deux méthodes NEMD ont révélé une très forte rétention saline, confirmant ainsi la pertinence du modèle de membrane d'OI développé dans ce travailReverse osmosis (RO) is currently the leading process used worldwide for both brackish and seawater desalination. This thesis focuses on the molecular simulation of RO membranes in order to improve the understanding of structure, dynamics and transport of water and ions inside these materials. The RO membrane studied in this work is a typical polyamide RO membrane. In the first step of this work, a methodology for building a fully atomic and three-dimensional model of a highly cross-linked polyamide membrane was developed. Both equilibrium molecular dynamics (EMD) and non-equilibrium molecular dynamics (NEMD) simulations were further performed to investigate the behavior of water and ions (Na+ and Cl-) through the membrane. EMD simulations showed that the structural characteristics of the model polyamide membrane were in good agreement with those of a typical RO membrane. The dynamics and dielectric properties of water confined in the RO membrane were also studied and have shown to be dramatically modified with respect to the bulk phase. Two types of NEMD techniques were employed to investigate pressure-driven transport through the model membrane. Pure water permeability was found to be in very good agreement with experimental data reported in the literature for similar membrane materials and both NEMD methods highlighted very high salt rejection properties, thus confirming the relevance of the model membrane developed in this work
7
Al-Jeshi, Subhi. "The effect of reverse osmosis membrane microscopic structure on its performance and reverse osmosis performance in oily water". Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/348.
Testo completo
8
Xie, Zhangwang. "Polysaccharide fouling in reverse osmosis and forward osmosis desalination and its alleviation". Thesis, Xie, Zhangwang (2015) Polysaccharide fouling in reverse osmosis and forward osmosis desalination and its alleviation. PhD thesis, Murdoch University, 2015. https://researchrepository.murdoch.edu.au/id/eprint/31172/.
Testo completoAbstract (sommario):
Membrane separation processes, including forward osmosis (FO) and reverse osmosis (RO), for application in water desalination are plagued by membrane fouling. In particular, membrane biofouling is unpredictable in its nature and affected by numerous factors. One of the major contributors to biofouling is the extracellular polymeric substances (EPS) produced by bacteria, especially the polysaccharides that form a large part of EPS.
The objectives of this study are to understand the polysaccharide fouling mechanisms based on a comparison of polysaccharide fouling in FO and RO and to find suitable alleviating agents for polysaccharide fouling mitigation. Three major tasks were conducted in this study. Firstly, polysaccharide fouling in FO and RO were compared under identical solution chemistry and operational conditions to understand the respective fouling mechanisms in FO and RO. Secondly, some alleviating agents for mitigation of polysaccharide fouling in FO and RO were tested to demonstrate the fouling alleviation mechanism. Thirdly, a model of hydraulic resistances was developed to illustrate membrane fouling mechanisms based on analysis of the contribution of hydraulic resistances to permeate flux decline.
Major findings are:
1) Commercial polysaccharides and polysaccharides isolated from naturally adherent bacteria behaved differently in membrane fouling, which showed that alginate was not a typical model and it is important to select a proper model for polysaccharide fouling.
2) Under identical conditions, membrane fouling by both commercial and isolated polysaccharides was more severe in RO than FO, indicating the importance of pressure source in membrane fouling.
3) RO fouling was likely dominated by foulant – foulant interaction which was greatly affected by calcium ions, while FO fouling could be largely governed by foulant – membrane interaction, which was greatly influenced by solution viscosity.
4) Sodium nitroprusside (SNP) at a proper dose was found to be able to reduce membrane fouling, which could be explained by the electrostatic repulsion between polysaccharides and SNP.
5)Presence of calcium ions played a crucial role in polysaccharide fouling and its alleviation, with its presence leading to significant increase in cake resistance in RO fouling and reducing alleviation efficiency.
9
Nurlaila, Gita G. "Development of reverse osmosis low-pressure membranes". Thesis, University of Ottawa (Canada), 1997. http://hdl.handle.net/10393/4342.
Testo completoAbstract (sommario):
Thin film composite (TFC) membranes were developed for reverse osmosis (RO) under low pressure. Three commercial membranes, i.e. one type of polyvinylidene fluoride, namely AP-10, and two types of polyethersulfone, namely HW-18 and E-500, were used as substrate membranes. Sulfonated poly(2,6-dimethyl-1,4-phenyleneoxide), known as SPPO, was used as the ultrathin barrier layer of the composite membranes. The performances of the three substrate membranes were compared. The pore size and the pore size distribution of the substrate membranes were studied. Then the RO performances of the substrate membranes coated with SPPO were compared. It was observed that a high electrolyte separation without scarification of permeate flux was attained when membrane E-500 was used as the substrate membrane. Afterwards, the effects of the number of coating layers and the coating solution concentrations on RO performance of the TFC membranes, using E-500 membrane as the substrate membrane, were studied. The optimum coating solution concentration and the number of coating layers for maximum electrolyte separation were determined. The TFC membrane was then subjected to post-treatments, i.e. annealing and heat treatment under water, to improve the permeate flux. The final post-treated TFC membrane performance was concluded to be close to the targeted value.
10
Siddiqui, Farrukh Arsalan. "Membrane filtration : fouling and cleaning in forward osmosis, reverse osmosis, and ultrafiltration membranes". Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:bcaadfaa-62fb-4910-8218-bff387a19a11.
Testo completoAbstract (sommario):
A comparison of fouling in osmotically driven processes with that in pressure driven processes is the main focus of the thesis. Forward osmosis (FO) and reverse osmosis (RO) have received considerable attention for water treatment and seawater desalination. This research compared the nature of fouling in FO mode with that in RO starting with the same initial flux in connection with cleaning effects and then comparing to those in ultrafiltration membranes. In all cases, with cleaning as an integral part, the extent of fouling reversibility, and the question whether a critical flux could be determined were examined. The work during the first phase (undertaken at Oxford) quantified the removal of reversible fouling through rinsing by cold and hot water for a range of concentrations using the foulants dextran and carboxymethyl cellulose. The flux-TMP relationship was conventionally compared to that of the clean water flux. The later phase (at Singapore) compared the fouling in FO and RO by alginate in terms of multiple parameters using cellulose tri acetate (CTA) and thin film composite (TFC) membranes. Silica and alginate were selected as model foulants. Whilst experimental water flux profiles in the present study did not exhibit significant differences in trend between FO and RO fouling, foulant resistance for FO was found to be increasingly greater than for RO with the progression of the fouling tests. This was further corroborated by membrane autopsies post fouling tests; both foulant mass deposition density and specific foulant resistance for FO were greater than for RO. The analysis clearly revealed that FO is essentially more prone to fouling than RO which was presumably due to less flux decline in FO (or greater average flux) as compared to that in RO in result of ICP-self compensation effect which is opposite to the prevailing claim in the literature. Additionally, the present study did not find evidence that hydraulic pressure in RO has a role in foulant layer compaction. FO membrane fouling by real waters was the focus of the final phase of the research at SMTC. Pilot scale FO experiments were conducted on spiral wound CTA membrane with treated waste water obtained from a NEWater factory (Singapore) as the feed. In the second stage, experiments were repeated at bench scale with membrane coupons taken from the spiral wound membranes used earlier. The key finding was that the mass transfer coefficients in the Spiral-Wound module were around 50% lower than the corresponding values in the flat sheet unit and this severely limited the fluxes. The reason could be attributed to strong internal concentration polarisation in the former, where tightly wound spacers act to increase the structural parameter.
11
MendonÃa, Doglasse Ernesto. "Osmosis reverse plant powered by photovoltaic modules with MPPT and self regulated pressure valve". Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16455.
Testo completoAbstract (sommario):
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoThis project presents a brackish water desalination plant via Reverse Osmosis (RO) powered by Photovoltaic Modules (PV) with Maximum Power Tracking (MPPT) and a self â regulating pressure valve. The developed unit is installed on Alternative Energy Laboratory (LEA), which is located on the campus of PICI at Federal University of CearÃ. To extract maximum power from the PV module a Buck type converter was developed for this application. The Incremental Conductance algorithms (IncCond) is used. The MPPT technique was simulated, tested and validated, showing an efficiency of 86.8%. An innovation in this plant is the use of a self-regulating pressure valve installed in the concentrate output, which ensures a smaller pressure and power variation in the pump that is responsible for pressurizing the water to the membranes. The technical feasibility of the RO plant is checked in two phases: one without the presence of the self- regulating pressure valve in the concentrated output and other with the self-regulating pressure valve in the concentrated output. The plant is tested for two salinity levels 1000 and 1500 mg/L of TDS (Total Dissolved Solids) levels. These salinity levels chosen are commonly found in most brackish water wells of the semi-arid region of Northeastern Brazil. For operation without selfregulating pressure valve the obtained average values are: recovery rate 8.03% (relation between permeate flow and feed water flow), 151.7 L of daily production of drinking water with 130 mg/L of TDS, specific energy consumption of 2.68 kWh/m3. For operation with self-regulating pressure valve the obtained average values are: recovery rate 8.14%, 175.3 L of daily production of drinking water with 120 mg/L of TDS, specific energy consumption of 2.56 kWh/m3. Thus the configuration system using the self â regulating valve showed better results
O presente projecto apresenta uma planta de dessalinizaÃÃo de Ãgua salobra por osmose reversa (OR) acionada por mÃdulos fotovoltaicos (FV) com seguimento de potÃncia mÃxima (MPPT - Maximum Power Point Tracking) e vÃlvula autoreguladora de pressÃo. A planta desenvolvida està instalada no LaboratÃrio de Energias Alternativas (LEA), situado no Campus do PICI da Universidade Federal do CearÃ. Para extraÃÃo da mÃxima de energia do mÃdulo FV foi desenvolvido um conversor do tipo Buck, usando a tÃcnica CondutÃncia Incremental (CondInc). A tÃcnica de MPPT foi simulada, testada e validada, apresentando uma eficiÃncia de 86,8% no seguimento do ponto de potÃncia mÃxima. Uma inovaÃÃo na planta proposta à o uso de uma vÃlvula autoreguladora de pressÃo instalada na saÃda do concentrado, que garante uma menor variaÃÃo de pressÃo e corrente eletrica na motobomba responsÃvel por pressurizaÃÃo da Ãgua para as membranas. A planta de OR foi testada em duas etapas: uma sem a presenÃa da vÃlvula auto-reguladora de pressÃo e a outra com a vÃlvula, para uma Ãgua de alimentaÃÃo entre os nÃveis de salinidade de 1000 e 1500 mg/L de STD (SÃlidos Totais Dissolvidos). Estes nÃveis de salinidade adotados sÃo geralmente encontrados em poÃos com Ãgua salobra do semiÃrido do Nordeste do Brasil e noutros casos maior 1500 mg/L de STD. Para a operaÃÃo sem a vÃlvula autoreguladora de pressÃo foram obtidos os seguintes valores mÃdios: taxa de recuperaÃÃo 8,03%, produÃÃo de Ãgua potÃvel de 151,7 L/dia com 130 mg/L de STD, consumo especÃfico de energia de 2,68 kWh/m3. Para a operaÃÃo com a vÃlvula autoreguladora de pressÃo foram obtidos os seguintes valores mÃdios: taxa de recuperaÃÃo 8,14%, produÃÃo de Ãgua potÃvel de 175,3 L/dia com 120 mg/L de STD, consumo especÃfico de energia de 2,56 kWh/m3. No entanto a configuraÃÃo da planta operando com a vÃlvula autoreguladora de pressÃo apresenta melhores resultados relativamente a operaÃÃo sem a vÃlvula.
12
Fang, Yi. "Fractionation of organic liquid mixtures by reverse osmosis". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5890.
Testo completoAbstract (sommario):
A systematic investigation has been conducted to demonstrate the general applicability of reverse osmosis (RO) fractionation of organic liquid mixtures by laboratory prepared cellulose acetate butyrate (CAB) and aromatic polyamide (PA) membranes. Surface excess values have been determined by liquid chromatography (LC) technique for the four model organic liquid mixtures for CAB and PA materials. The principal findings of this study are: (i) separations take place in all the four model organic liquid mixtures, and PA membranes given separations higher than CAB membranes under same experimental conditions; (ii) preferential sorption exists in all the four model systems for CAB and PA materials, (iii) the RO results are explained by the combined consideration of surface excess data determined from LC, and Stokes' Law radius calculated from literature data.
13
Bouma, Andrew Thomas. "Split-feed counterflow reverse osmosis for brine concentration". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118668.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 73-77).
Brine concentration is a useful operation that allows for increased recovery ratios in water treatment systems, reduction of waste volumes, and the production of minerals from saline brines. As our world moves towards a more sustainable future, improvements in energy-efficient brine concentration will be important. While viable brine concentration technologies exist, current methods are often inefficient. In this thesis, a model is developed to simulate Counterflow Reverse Osmosis (CFRO), a membrane-based, pressure-driven brine concentration technology. Using this model, a single CFRO module is simulated and its performance characterized. Entropy generation within a single-stage system is analyzed, which provides insights for configuring and optimizing multistaged systems. Additionally, a parametric analysis of membrane parameters provides direction for the development of CFRO-specific membranes. Two existing configurations of CFRO are discussed, and compared with a new third configuration, split feed CFRO, which is presented for the first time here. Split feed CFRO systems are simulated and optimized to provide guidance for system design. A variety of multistage systems operating at a range of recovery ratios are simulated, and the results compared are with existing desalination and brine concentration technologies. Potential is shown for the maximum recovery ratio of RO systems to increase significantly when hybridized with split-feed CFRO brine concentration systems, while the energy requirements of these hybridized systems is similar to, or an improvement on, the expected performance of conventional RO systems operating at high pressures and the same conditions. A large reduction in energy usage when compared to commonly used evaporative brine concentrators is shown to be possible.
Funded by the Kuwait Foundation for the Advancement of Sciences (KFAS) Project No. P31475EC01
by Andrew Thomas Bouma.
S.M.
14
Kovacs, Jason Richard. "Engineering nanostructured selective layers for reverse osmosis membranes". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98709.
Testo completoAbstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 122-142).
A major challenge to communities across the world in the next century will be ensuring millions have access to adequate freshwater resources. Studies from the UN World Health Organization indicate that over 1.1 billion people currently lack access to reliable and secure freshwater supplies, with an estimated 2.5 million deaths per year from diseases associated with poor access and sanitation in 2007. Reverse osmosis (RO), a process through which water is desalted via pressurized flow past a salt-selective membrane, is an energy-efficient method to generate freshwater from oceanic, brackish, and waste water sources. However, there are a number of challenges to scaling up RO processes to large scale production, including the need to improve membrane selectivity and throughput. One method to assemble selective layers for RO membranes is layer-by-layer (LbL) assembly, which is a flexible, scalable assembly technique that enables the incorporation of a myriad of polyelectrolytes and inorganic nanoparticles into thin films. There is a gap in the scientific literature concerning the use of LbL to generate RO selective layers where previous approaches have not taken full advantage of the LbL process to incorporate nanomaterials that can generate ordered nanostructures for salt rejection. In particular, high-aspect ratio clay platelets are ideal for such a purpose; it was hypothesized that effective salt rejection could be achieved by hindering the diffusion of solvated ions through nano-channels formed by the platelets embedded within a polymer matrix. This body of work examines the application of spray layer-by-layer (spray-LbL) assembly with clay composite thin film architectures to generate nanostructured selective layers for use in RO membrane technology. First, appropriate substrates were identified as support layers for the deposition of spray- LbL assembled clay composite thin films. Both electrospun bisphenol-A polysulfone (PSU) mats of varying fiber diameter and polyethersulfone (PES) ultrafiltration (UF) membranes with varying pore diameters were examined. Second, a range of materials were investigated for the spray-LbL deposition of clay composite films. Laponite clay platelets were incorporated into several different film architectures including strong polyelectrolytes as well as cross-linkable weak polyelectrolytes to form both bilayer and tetralayer film architectures. The clay content was controlled via manipulating assembly conditions such as the pH and spray times of the film components. Assembled membrane architectures were tested at industrial RO operating conditions in dead-end permeation cells and evaluated for salt rejection, water permeability, and mechanical strength. Ultimately, it was determined the most uniform and robust films were those deposited on PES membranes with 30 nm pores, closely matching the characteristic length of the LAP clay platelets to reduce the impact of bridging. Although all the film architectures tested exhibited significantly greater water permeability than commercially available RO selective layers, the salt selectivity was found to be highly dependent on the film architecture and assembly conditions. The best performing film architecture consisted of a cross-linked clay composite tetralayer film, exhibiting salt rejection of 89% for aqueous 10,000 ppm NaCl solution with an order of magnitude increase in water permeability over a commercially-available thin film composite membrane. The key conclusion drawn from the studies indicate the presence of an optimal zone where the incorporation of clay platelets introduces additional salt selectivity via size exclusion, balanced with the cross-linked polymer component of the film to improve the mechanical strength and reduce the risk of critical defect formation during operation. Taken together, these investigations represent a new approach using structured nanomaterials to develop next generation clay composite RO selective layers. The increased water permeability of the clay composite selective layers offers an attractive advantage in desalting applications where high flux is desirable, such as with brackish water resources as well as in membrane unit operations near their thermodynamic limit.
by Jason Richard Kovacs.
Ph. D.
15
Detrich, Kahlil. "Electroding Methods for in situ Reverse Osmosis Sensors". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/31207.
Testo completoAbstract (sommario):
The purpose of this work is to develop and evaluate electroding methods for a reverse osmosis (RO) membrane that results in an in situ sensor able to detect RO membrane protein fouling. Four electroding techniques were explored: i) gold exchange-reduction, ii) encapsulated carbon grease, iii) â direct assembly processâ (DAP), and iv) platinized polymer graft. The novel platinized polymer graft method involves chemically modifying the RO membrane surface to facilitate platinization based on the hypothesis that deposition of foulant on the platinized surface will affect platinum/foulant/solution interfacial regions, thus sensor impedance. Platinized polymer graft sensors were shown to be sensitive to protein fouling.
Electrodes were characterized by their electrical properties, SEM and XPS. Assembled sensors were evaluated for sensitivity to electrolyte concentration and protein fouling. Micrographs showed coating layers and pre-soak solution influence gold exchange-reduction electrode formation. High surface resistance makes gold exchange-reduction an unsuitable method. Concentration sensitivity experiments showed carbon grease and DAP electroding methods produce unusable sensors. Carbon grease sensors have time-dependent impedance response due to electrolyte diffusion within the micro-porous polysulfone support. DAP electroded sensors proved quite fragile upon hydration; their impedance response is transient and lacks predictable trends with changes in concentration. A parametric study of the platinized polymer graft method shows amount of grafted monomer correlates to grafting time, and deposited platinum is a function of exchange-reduction repetitions and amount of grafted monomer. Platinized polymer graft sensors were fouled in both dead-end and cross-flow RO systems, and their impedance trends, while varying between sensors, indicate protein-fouling sensitivity.Master of Science
16
Al, Shaalan Hakem. "Artifical neural network modelling of reverse osmosis process". Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9516.
Testo completoAbstract (sommario):
With the increase in population and the scarcity of fresh water in the Middle East desalination has taken an important role in the provision of water for everyday use and for industrial purposes. Reverse osmosis water treatment process is of particular interest as it is one of the key processes in a desalination plant. The modelling of this process and the prediction of permeate flow is useful in better understanding the process. In the present study, an artificial neural network based model was developed based on plant data for the prediction of permeate flow performance. Plant data was collected and a number of variables determined. Principal component analysis was then carried and factor loadings obtained to identify the main variables. Once the main input variables were obtained a statistical analysis of the data was done in order to remove outliers present in the data. This was done because the presence of outliers in data to be analysed using ANN models renders the models ineffective in prediction of an output. Once the removal of outliers was done, the data was then analysed using the developed model. 1081 sets of data were originally used with twelve input variables. After principal component analysis was done the input variables were reduced to five with one output variable. With the removal of outliers 981 sets of data were obtained and these were then used in the model. The model was able to predict the output accurately with r2 at 0.97. Key factors determined from the process were that to obtain an optimum network one has to consider the epoch size, the transfer function, the learning rate and finally the number of nodes in the hidden layers. The number of hidden layers also had an effect on the overall prediction of the data. It is also important when using ANN models to obtain the correct input variables and to remove any outliers that are present in the data in order to be able to predict the output. The use of plant data severely limited optimisation of the process due to it already being heavily optimised.
17
Harrison, Don. "Solar powered reverse osmosis desalination for remote communities". Thesis, Harrison, Don (1989) Solar powered reverse osmosis desalination for remote communities. Honours thesis, Murdoch University, 1989. https://researchrepository.murdoch.edu.au/id/eprint/40085/.
Testo completoAbstract (sommario):
Many Aboriginal Outstations in Western Australia have bores which produce drinking water of such a low standard that the health of the community members is at risk. Major concerns are the high concentrations of sale, nitrates and fluoride and bacteriological contamination. Communities faced with this problem have four choices. They can sink another bore nearby in the hope of finding better water, which would be expensive and not necessarily successful. They can physically move to another location which would be socially and culturally disruptive. They can accept the risk and drink the water untreated. Recent innovations in reserve osmosis desalination now make it possible to treat the water on site using solar power.
The appropriateness of this new technology for remote locations is analysed. A means of predicting the power requirements of a unit capable of supplying the drinking water needs of a small community, estimated at up to 1 m3 per day is derived. A small commercially available unit was tested and it was found that in summer it could produce a steady flow of over 5 L/hour for 10 hours per day when used with a solar tracker and a power optimiser. Two designs were developed which could supply the desired 1 m3 flow rate from the power of two 55 W solar panels. A prototype of one design has been constructed and early testing demonstrate that is is capable of producing up to 400 L/day even at low pump efficiencies. Minor improvements are likely to substantially improve production in the near future.
18
Susanto-Lee, Robertus. "Efficiency improvements for small-scale reverse-osmosis systems". Thesis, Curtin University, 2006. http://hdl.handle.net/20.500.11937/286.
Testo completoAbstract (sommario):
The water supplies of some small inland communities may come in the form of river systems that offer brackish water. Not fit for immediate human consumption, the water can be further processed using reverse osmosis to be converted into drinking water.In very remote areas there are limited energy resources, and for those areas that lie beyond a municipal distribution grid, renewable energy sources may be used. A reverse osmosis system that operates from the limited power generated by a renewable energy system must do so with the utmost of efficiency. Three methods in improving the efficiency of small-scale reverse-osmosis system are investigated, namely high-pressure pump speed control, feed water heating and vacuum pump based energy recovery.
19
Susanto-Lee, Robertus. "Efficiency improvements for small-scale reverse-osmosis systems". Curtin University of Technology, Department of Electrical Engineering, 2006. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=16974.
Testo completoAbstract (sommario):
The water supplies of some small inland communities may come in the form of river systems that offer brackish water. Not fit for immediate human consumption, the water can be further processed using reverse osmosis to be converted into drinking water.In very remote areas there are limited energy resources, and for those areas that lie beyond a municipal distribution grid, renewable energy sources may be used. A reverse osmosis system that operates from the limited power generated by a renewable energy system must do so with the utmost of efficiency. Three methods in improving the efficiency of small-scale reverse-osmosis system are investigated, namely high-pressure pump speed control, feed water heating and vacuum pump based energy recovery.
20
Robinson, Michael Anthony. "Removal of organic contaminants from groundwater by reverse osmosis /". This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03142009-040729/.
Testo completo
21
Hoffman, Anton Michael. "Design guidelines for a reverse osmosis desalination plant / Anton Michael Hoffman". Thesis, North-West University, 2008. http://hdl.handle.net/10394/4211.
Testo completoAbstract (sommario):
There are two basic needs globally and that is the control and supply of
reliable electricity and clean water. However, one of the biggest challenges
the world is facing today is the lack of fresh water resources. Lower rainfall,
together with population and industry growth, are only a few factors
contributing to the fast increasing strain on existing water supplies around the
world. This fast increasing need therefore necessitates the investigation into
finding alternative sources. One such option is that of desalination. In the last
50 years desalination technologies have been applied to produce high quality
fresh water from brackish and seawater resources. In the 1980's a breakthrough
was made with the introduction of the membrane desalination
technology, known as the reverse osmosis (RO) process.
Today newly developed technologies are improving the competitiveness of the
reverse osmosis process against the traditional distillation processes. There
are a number of options to increase the efficiency of a reverse osmosis plant
and one option is to use warm industrial waste water as the feed water to the
desalination plant. It is known that the viscosity of water is inversely
proportional to its temperature. Therefore, if the feed water temperature of a
reverse osmosis plant is increased the membranes will become more
permeable. This will result in a higher production volume or in a lower energy
demand. South Africa is on the edge of building the first fourth generation
nuclear power plant, called the Pebble Bed Modular Reactor (PBMR) at
Koeberg. The PBMR will produce a cooling water outlet temperature of 40°C
which can be used as feed water to a reverse osmosis plant.
In this study design guidelines of a reverse osmosis plant are given in nine
steps. These steps were then used during a basic component design of a
reverse osmosis plant coupled to the waste water stream of a PBMR nuclear
power plant. Furthermore design software programs were used to simulate
the coupling scheme in order to validate the outcome of the design guidelines.
The results of the two design approaches compared well to one another. It
furthermore showed that by using the waste water from the PBMR nuclear
power plant the efficiency of the RO plant is increased and the operating cost
is decreased. Fresh water can be produced at a cost of R 5.64/m3 with a
specific electricity consumption of 2.53 kWh/m3.Thesis (M.Ing. (Nuclear Engineering)--North-West University, Potchefstroom Campus, 2009.
22
Massons, Gassol Gerard. "Biofouling control in reverse osmosis membranes for water treatment". Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/461092.
Testo completoAbstract (sommario):
L’osmosi inversa (OI) és una de les tecnologies de purificació d'aigua més competitives. Els sistemes d'OI han evolucionat significativament en els últims anys per a proporcionar solucions reals i sostenibles als problemes relacionats amb l'aigua. Un dels principals obstacles que impedeix l'expansió en l'ús d'OI en la reutilització de l'aigua, és la pèrdua de rendiment que els elements d'OI experimenten a l'operar amb aigües contaminades. Aquest fenomen de embrutament continua sent un dels majors reptes a resoldre per elements de OI utilitzats en plantes industrials o de tractament d'aigües residuals.
A causa de la complexitat d'estudiar aquests problemes en sistemes d'escala industrial, és necessari desenvolupar protocols per reproduir els efectes en equips de laboratori. Els efectes de l’embrutament solen apareixer després de diversos mesos. No obstant, per poder realitzar la recerca en un temps realista, el procés ha ser accelerat de forma controlada i el més realista possible. S'ha estudiat l'efecte de diferents variables operacionals en el desenvolupament de l’embrutament biològic. També s'ha avaluat el paper dels paràmetres de construcció de mòduls d'OI, provant en paral·lel diferents membranes i espaciadors, per millorar el disseny d'elements resistents al embrutament.
Els resultats dels assaigs realitzats demostren clarament que diferents químiques de membrana poden proporcionar una reducció significativa en els nivells de embrutament. Tot i això, es va trobar que el principal contribuent al desenvolupament dels biofilms es el espaciador. El disseny de l'espaciador es va estudiar en detall per aconseguir un comportament equilibrat en mòduls d'OI que tracten aigües amb un risc d’embrutament biològic elevat. Es van probar espaciadors amb diferents espessors, separacions i angles. Alguns dissenys van mostrar avantatges en la perdua de pressió generada, així com en l'acumulació d’embrutament biològic i orgànic.La osmosis inversa (OI) es una de las tecnologías de purificación de agua más competitivas. Los sistemas de OI han evolucionado significativamente en los últimos años para proporcionar soluciones reales y sostenibles a los problemas relacionados con el agua. Uno de los principales obstáculos que impide la expansión del uso de OI en la reutilización del agua es la pérdida de rendimiento que los elementos de OI experimentan al operar con aguas contaminadas. Este fenómeno de ensuciamiento sigue siendo uno de los mayores desafíos para los elementos de OI utilizados en plantas industriales o de tratamiento de aguas residuales. Debido a la complejidad de estudiar estos problemas en sistemas de escala industrial, es necesario desarrollar protocolos para reproducir los efectos en equipos de laboratorio. Los efectos del ensuciamiento suelen ocurrir después de varios meses. Sin embargo, para poder realizar la investigación en un tiempo realista, el proceso necesita ser acelerado de manera controlada y lo más realista posible. Se ha estudiado el efecto de diferentes variables operacionales en el desarrollo del ensuciamiento biológico. También se ha evaluado el papel de los parámetros de construcción de módulos de OI, probando en paralelo diferentes membranas y espaciadores, para mejorar el diseño de elementos resistentes al ensuciamiento. Los resultados de los ensayos realizados mostraron claramente que diferentes químicas de membrana pueden proporcionar una reducción significativa en los niveles de bioensuciamiento. Sin embargo, se encontró que el principal contribuyente al desarrollo de biofilms fue el espaciador. El diseño del espaciador se estudió en detalle para lograr un comportamiento equilibrado en módulos de OI que tratan aguas propensas al ensuciamiento biológico. Se ensayaron espaciadores con diferentes espesores, espaciamiento y ángulo. Algunos diseños mostraron ventajas en la perdida presión generada, así como en la acumulación de ensuciamiento biológico y orgánico.
Reverses osmosis (RO) filtration is one of the most competitive water purification technologies. RO systems have evolved significantly in the last years to provide real and sustainable solutions to water-related problems. One of the main hurdles that hinders RO expansion in water reuse, is the loss of performance that RO elements suffer when dealing with contaminated waters. This phenomenon known as fouling, remains to be one of the biggest challenges for RO elements used in industrial or wastewater treatment plants. Due to the complexity to study these problems in large scale systems, protocols need to be developed in order to mimic full-scale plants operation on a bench scale. Fouling problems are usually occurring after several month of operations. However, for a realistic time-scale research, the process needs to be accelerated in a controlled way and as similar as possible to what would be occurring naturally. The effect of different operating variables on biofouling development was studied. The role of RO module construction was also evaluated, testing different membranes and feed spacers side-by-side, to guide the improvements on the design of fouling resistant elements. The results from the trials performed clearly showed that different membrane chemistries can provide significant reduction in the levels of biofouling detected after operation. However, it was found that the main contributor to biofilm development was feed spacer. Large differences in the amount of biofouling generated could be associated with feed spacer presence. Feed spacer design was then studied in detail to achieve a balanced performance in spiral wound RO modules treating waters prone to biofouling. Feed spacers with various thickness, spacing and angle were tested and some designs showed advantages in pressure drops, as well as on biologic and organic fouling accumulation.
23
Hurd, Sarah M. "Low-pressure reverse osmosis membrane treatment of landfill leachate". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0025/MQ52299.pdf.
Testo completo
24
Ashhuby, Bashir Ali. "Biofouling studies on reverse osmosis desalination of hypersaline waters". Thesis, University of Sheffield, 2007. http://etheses.whiterose.ac.uk/3599/.
Testo completoAbstract (sommario):
Biological fouling of reverse osmosis (RO) membranes is affected by many factors, and it is not clearly understood, especially with respect to hypersaline waters. Biofouling minimisation requires understanding of the fundamentals of the biofilm development. It is also necessary to monitor biofilm development at various stages and its relation to concentration polarisation phenomena. The two main goals were to explore the biological diversity of a hypersaline lake called "Qabar-Onn"t located in the Sahara; and to better understand what biotic and abiotic factors govem biofouling of RO membranes treating hypersaline waters. Three halotolerant bacterial strains (Euhalothece species, BAAOOl and BAA002, and Halomonas pantelleriensis species, BAA003) were isolated from the lake using conventional culturing methods, and were identified based on 16S rRNA sequencing. Two isolated species, Eukalothece species BAAOOI and Halomonas pantelleriensis species BAA003 were used as model microorganisms to evaluate the potential of biofilm development on RO membranes. Salinity and surface roughness, which affect biofilm initiation and growth, were investigated. A novel, in-situ monitoring device was used to detect initiation of biofilm formation, and its relation to solutes and concentrations near RO membrane surfaces. The results showed that Qabar-Onn Lake is inhabited by a wide range of microorganisms, which seem to have a strong potential to adapt to the rapid increase in the lake salinity. In addition to salinity, pH also is limiting factor on biodiversity and microorganisms' dominance. Biofouling was strongly controlled by membrane characteristics and feed salinity. Lower surface roughness and low salinity contributed to less biofilm formation. Furthermore, the absence of monovalent anions (i. e. chloride) in the feed enhanced flux at low salinities; however, its absence severely decreased flux at higher salinities. Similarly, microorganisms present in the feed extremely enhanced the permeate flux at low salinities, however, at high salinities the flux decreased in the presence of microorganisms.
25
Robinson, Michael A. "Removal of organic contaminants from groundwater by reverse osmosis". Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41621.
Testo completoAbstract (sommario):
The performance of a poly(ether/urea) membrane has been evaluated in a full scale reverse osmosis system. A series of experiments were conducted with six aromatic compounds - anthracene, pyrene, fluorene, 2-chlorobiphenyl, 2,4,6 trichlorophenol, and pentachlorophenol- and four volatile compounds - trichloromethane, bromodichloromethane, dibromochloromethane, and trichloroethene - as single and multi-solute contaminants. The objectives of the experiments were to determine if poly(ether/urea) membranes could produce a permeate that met maximum contaminant levels (MCL) set by the Safe Drinking Water Act (SDWA) and to correlate membrane performance with physical/chemical properties of the solute contaminants.
Aromatic contaminants were removed to concentrations below the current MCLs. However, volatile contaminants were not sufficiently rejected by the membrane to meet either the MCL for total trihalomethanes or trichloroethene.
Sorption onto the poly(ether/urea) was found to occur for several of the aromatic compounds tested in this research. This prevented developing any relationship between membrane performance and physical/chemical properties of the solute.Master of Science
26
Malherbe, Gideon Francois. "Development and application of ultrafiltration and reverse osmosis membranes". Thesis, Cape Technikon, 1993. http://hdl.handle.net/20.500.11838/908.
Testo completoAbstract (sommario):
Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town,1993Various experimental and established membranes were tested on industrial effluents. Ultrafiltration, reverse osmosis and nanofiltration membranes were used in various applications. Research was done on aspects such as the cleaning of fouled membranes, production quality control and process development. Polyvinyl alcohol ultra-thin-film reverse osmosis membranes were manufactured for the desalination of brackish water to a potable standard. The membranes were manufactured in the tubular configuration. Experimental ultrafiltration, reverse osmosis and nanofiltration membranes were tested on cooling water blowdown on a laboratory-scale. On-site testing was done directly on the effluent at a later stage. A s!udy was also conducted to determine the effect of gel-polarization on membrane performance. The gel-layer model was used to predict the limiting flux of specific membranes. Membrane processes were also applied in the fractionation of wine-lees to provide usable by-products such as yeast cells and potassium bitartrate. Ultrafiltration membranes operated in diafiltration mode were used to "wash" the slurry at different solid concentrations. The bitartrate-rich permeate collected from ultrafiltration was then concentrated using reverse osmosis and nanofiltration to allow subsequent precipitation of the product.
27
GUPTA, VINEET K. "EXPERIMENTAL AND THEORETICAL STUDIES IN REVERSE OSMOSIS AND NANOFILTRATION". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061233200.
Testo completo
28
Harrison, Don. "Solar powered reverse osmosis desalination: Technology for remote communities". Thesis, Harrison, Don (2001) Solar powered reverse osmosis desalination: Technology for remote communities. PhD thesis, Murdoch University, 2001. https://researchrepository.murdoch.edu.au/id/eprint/52404/.
Testo completoAbstract (sommario):
The need for desalination to provide drinking water of acceptable standards has been established. A review of desalination techniques suggests that solar powered reverse osmosis with energy recovery is likely to satisfy the widest range of applications in inland Australia and elsewhere. Of the energy recovery techniques, the 'flow-regulated' approach appears well suited to remote applications, because it maintains its set recovery ratio regardless of insolation levels, and starts and stops automatically at sunrise and sunset. Operating and capital costs of units needs to be minimised and operational flexibility maximised for wide application in remote areas.
This project aimed to develop, produce and test a low cost solar powered desalinator that was portable, reliable and flexible. The thesis describes the theoretical and practical development of a production model through the four prototypes. The prototypes were tested to determine the performance of a variety of membranes, the efficiency of the pumps and energy recovery system, and the water slippage of valves and seals. The available energy from the two-panel tracking array was also assessed.
A model which describes the hydraulics of 'flow-regulated' energy recovery systems was developed and incorporated in a spreadsheet program and used to assess the performance of the prototypes. The relevance of all the variable components affecting fresh water production can be assessed through graphically presented results from the spreadsheet.
A production model solar powered desalinator capable of 400 L/day from a 120 W peak array has been developed as a result of the project. The flow-regulated approach to energy recovery appears to work well in the field and may be contributing to the maintenance of high water production rates at all sites without resorting to chemical pretreatment or frequent cleaning. High pulsation rates and low feed flow rates through large diameter spiral wound membranes do not appear to adversely affect membrane life at the low pressures used in these machines.
Further research is required to monitor the long term reliability and running costs of these machines, their degree of acceptance in remote communities, and their ability to maintain the quality of product water to acceptable standards.
29
Tshuma, Ivonne. "Brackish water treatment using pressure retarded osmosis (PRO) as a driving force for reverse osmosis (RO)". Thesis, Tshuma, Ivonne (2021) Brackish water treatment using pressure retarded osmosis (PRO) as a driving force for reverse osmosis (RO). PhD thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/61548/.
Testo completoAbstract (sommario):
The desalination process removes salts and contaminants from water to make it suitable for drinking and other beneficial purposes. Although Reverse Osmosis (RO) is currently the most energy-efficient, widely used desalination technology, it still requires a great deal of energy to create the high pressure necessary to desalinate seawater. The largest operating cost is the energy consumed in overcoming osmotic pressure and membrane resistance. Pressure Retarded Osmosis (PRO), on the other hand, utilises the salinity gradient between two solutions of different salt content to produce pressure, which can subsequently be used to generate electrical energy.
This thesis describes how PRO can be used directly as the sole energy source for RO in an autonomous PRO-RO system without additional energy input without converting osmotic energy into electrical energy. The PRO-RO proof of concept was experimentally verified in a simple combined cell without cross-flow resulting in 12.5 bars of hydraulic pressure, and flux of 3.5 L m-2 hr-1 in the RO permeate. The PRO-RO system used PRO and RO brackish water feed solution and concentrated brine PRO draw solution (200 g/L NaCl).
PRO is typically driven by freshwater to seawater gradient, but far greater energy can be predicted using hypersaline draw solutions. This study investigates the power density and maximum flux obtainable from two such saltwater solutions. The experimental data was verified by a transient model that predicts well (within 10%) PRO flux for all draw solution concentrations coupled with deionised water as feed. However, lower agreement with laboratory results was found for draw concentrations above 100 g/L when coupled with salty feed. Draw and feed cross-flow velocity were optimised at 0.1 m/s and 0.17 m/s, respectively.
A cellulose tri-acetate forward osmosis membrane was used for experimental evaluation of power production by a PRO apparatus with pressure generation up to 40 bars. A numerical model was produced from the first principles and established theory on osmotic systems to aid understanding and project beyond the practical experimental results.
The concept of combining the PRO driven by hypersaline and brackish water with a brackish water RO was investigated by modelling and simple proof of concept experiments. Theory suggests that the energy recovered from a PRO system keeps increasing with the draw solution's salt concentration. However, draw concentrations above 150 g/L did not result in a further increase in observed flux and observed energy (with a maximum pressure of 40 bars). Despite no gain in flux, modelled optimal power densities of 1.29, 12.19, and 62.4 W/m2 were obtained with increasing draw solution concentrations of 70, 150, and 300 g/L, respectively, with seawater feed solutions.
A novel, autonomous pressure retarded osmosis (PRO) driven reverse osmosis (RO), with an energy recovery device (ERD), was proposed to replace RO high-pressure pumps. The experimental PRO power density outputs from seawater/brackish water feed with 300 g/L draw and RO power density requirements were analysed. Coupling PRO with RO at PRO maximum power densities was found not to be economically viable due to high pressures of 160 bars.
The power density of 19.1 W/m2, achieved with brackish (10 g/L) feed and 300g/L draw, was sufficient to desalinate brackish water by RO at 30 bar pressure. Overall, brackish water feed and 300 g/L draw solution were used to model direct PRO to RO coupling efficacy. Using these feed and draw concentrations and the projected fluxes using currently available membranes, direct PRO to RO coupling of 2 m2 of PRO membrane to 1 m2 of RO membrane would produce 12.4 L m2 hr-1 of RO permeate at 30 bar applied pressure in an autonomous PRO-RO system.
30
Chong, Brian S. H. "The removal of pesticides and heavy metals by reverse osmosis". Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42126.
Testo completo
31
Martínez, de Peón Carolina. "Organic micropollutants in reverse osmosis water treatments, presence and rejection". Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/293903.
Testo completoAbstract (sommario):
En la present Tesis Doctoral es descriuen els diferents tractaments d'aigua i es centra en els tractaments avançats per membranes d'osmosis.
S'han creat mètodes analítics per quantificar diferents microcontaminants en mostres mediambientals aquoses i s'ha evaluat les membranes d'òsmosi inversa per a la seva eliminació.
També s'estudia l'embrutament orgànic de les membranes.En la presente Tesis Doctoral, se han estudiado los diferentes tratamientos del agua, poniendo énfasis a los tratamientos avanzados con membranas de ósmosis inversa. Se han desarrollado métodos analíticos apra la determinación de diferentes microcontaminantes orgánicos en aguas medioambientales, así como también el estudio de la eficiencia de las membranas de ósmosis inversa para la eliminación de estos contaminantes. Así mismo, se ha estudiado el ensuciamiento orgánico de las membranas caracterizando los compuestos presentes enn su superficie y correlacionandolos con el agua de alimentación de las membranas.
The first section, some water problems are described, as well as the different water treatments, quality parameters and regulations. The second section, a description of advance membrane treatments is included and reverse osmosis is studied to eliminate micropollutants from the water. The third section, the most common families of organic micropollutants studied in environmental waters are described. Some of these families are currently regulated. In addition, the analytical methodologies for these compounds determination are also described. Finally, the characterization of the organic fouling in reverse osmosis membranes and how it could interfere in the water treatment process by the advance treatments is described.
32
Miyashita, Yu. "Removal of N-nitrosamine by Nanofiltration and Reverse Osmosis Membranes". Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14490.
Testo completoAbstract (sommario):
The rejections of selected N-nitrosamines by commonly used high-pressure nanofiltration (NF) and reverse osmosis (RO) membranes were quantitatively evaluated using a bench-scale cross-flow filtration apparatus. The selected nitrosamines included N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosopyrrolidine (NPYR), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiphenylamine (NDPHA). Nitrosamine rejections were evaluated under steady state at elevated feed concentrations, since NDMA rejections were found to be consistent with feed concentrations over three orders of magnitude. The steady-state nitrosamine rejections by NF membranes varied significantly, from 9 to 75%, depending on nitrosamine compounds and tested membranes. For hydrophilic compounds, rejections increased with increasing molecular weight. The nitrosamine rejections by brackish RO membranes reached as high as 97% for higher molecular weight nitrosamines. However, for low molecular weight nitrosamines such as NDMA, rejections as low as 54% were observed. This low level of rejections was attributed to diffusive solute transport being more effective than convective transport. Physicochemical properties such as molecular weight and aqueous diffusivity showed reasonable correlations with nitrosamine permeability constants.
33
Thomson, A. Murray. "Reverse-osmosis desalination of seawater powered by photovoltaics without batteries". Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/10701.
Testo completoAbstract (sommario):
The design, construction and testing of a photovoltaic-powered reverse-osmosis (PV-RO) desalination system is presented. The system operates from seawater and requires no batteries, since the rate of production of freshwater varies throughout the day according to the available solar power. Initial testing of the system, with the modest solar resource available in the UK, provided freshwater at approximately 1.5 m³/day. Nearer to the equator and with a PV array of only 2.4 kWp, a software model of the system predicts production of over 3 m³/day throughout the year. The system employs a Clark pump brine-stream energy recovery mechanism and this, coupled with variable water recovery ratio, achieves a specific energy consumption of less than 4 kWh/m³ over a broad range of operation. Standard industrial inverters, motors and pumps are employed and provide good energy and cost efficiency. Maximum power point tracking (MPPT) for the photovoltaic array is provided by a novel control algorithm, developed by the author. Instrumentation and data acquisition of the hardware test rig using LabVIEW is described. Testing and modelling of the system components in MATLAB-Simulink is presented, together with a discussion of the full system modelling and design procedure, in which the aim was to minimise the cost of water. This led to a capital cost estimate of £23,055 includmg the PV array, and an overall cost of water, including full maintenance, of £2.00 per m³.
34
Wardeh, Sawsan. "Numerical modelling of reverse osmosis channels: application in desalination industry". Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490836.
Testo completoAbstract (sommario):
Reverse osmosis (RO) is widely used for the production of drinking water from brackish and sea water. In the RO process, pressure is used to separate water and salts by allowing water to pass through a semi permeable membrane leaving the salts behind. Therefore, controlling membrane fouling will help keep the productivity high. Having spacer filaments in the feed channel has been shown to reduce the concentration polarisation on the surfaces of the membrane and therefore fouling. This thesis focuses on the simulation of multiphase flow in spacer-filled channels using computational fluid dynamics (CFD).
35
Weldon, Kimberly Anne. "Transport properties of ion-exchange membranes used for reverse osmosis". Thesis, University of Exeter, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240386.
Testo completo
36
Richards, Laura Ann. "The removal of inorganic contaminants using nanofiltration and reverse osmosis". Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2577.
Testo completoAbstract (sommario):
Improved methods of providing safe drinking water are essential in an era in which demand for water is increasing but surface water supplies remain scarce. Desalination of brackish groundwater via membrane filtration with nanofiltration and reverse osmosis (NF/RO) offers a solution to this problem. As such, the overall motivation of this study was to improve mechanistic understanding of NF/RO. The first main aim was to evaluate the performance of a renewable energy membrane system previously tested with real groundwater and varying energy conditions. Given sufficient solar availability, the system reliably removed salts and inorganic contaminants, although solute retention varied with energy (and consequently pressure and flow) and pH, depending on dominant retention mechanisms. The second main aim was to assess the specific impact of pH on inorganic contaminant removal in a bench-scale filtration system. The speciation of boron, fluoride and nitrate was linked with ion retention as a function of pH, with results suggesting that there may be important mechanisms such as ion dehydration controlling transport in NF/RO, which would explain the high retention of fluoride when compared to nitrate. The third main aim was to determine the importance of ion hydration in determining transport using molecular dynamics simulations of monovalent anions transporting through an idealized pore. Simulations demonstrated that energy barriers of transport were strongly dependent on ion properties and pore size and were directly attributable to dehydration. The final aim was to experimentally verify molecular dynamics simulations by quantifying energy barriers for ion transport in NF membranes. Experimentally-determined energy barriers were also solute and membrane-specific, with fluoride having a higher barrier than other solutes. Comparison of results with expected dehydration trends and molecular dynamics corroborated that energy barriers in nanofiltration may be due to dehydration. The results obtained in this thesis provide new insight into NF/RO transport mechanisms, which may contribute to improvements in current technologies and predictive models.
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Powell, Lydia Charlotte. "The biofouling of reverse osmosis membranes : from characterisation to control". Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa42695.
Testo completoAbstract (sommario):
Membrane technology can be utilised for the high purification and desalination of water. However membrane filtration processes are commonly impeded by membrane fouling, which can lead to flux decline and an overall reduction in separation efficiency within the process. Therefore the aim of this research study was a comprehensive investigation of the issue of biofouling on industrial RO membranes through molecular biology techniques, characterisation of surface charge of foulant bacteria and RO membrane surface and AFM imaging and force measurements on clean and fouled membranes for the determination of adhesion force and micromechanical properties. The laboratories within Gwangju Institute of Science and Technology, South Korea and Swansea University, Wales were equipped for the scope of this research work. Research focused on the extraction of microbial DNA obtained from fouling layers on the surface of Reverse Osmosis Membranes obtained from the Fujairah Water and Power Plant, UAE. The use of the culture independent method of the molecular technique based on the 16S rDNA sequence and constructed gene libraries, was then used to determine the bacterial species that caused significant fouling on the RO membrane. Four bacterial species isolated from the fouling layer from the RO membrane were characterised in terms of electrophoretic mobility and zeta potential to determine the cell surface charge within various industrial relevant environments for the elucidation of cell adhesion mechanisms to the membrane surface. AFM images of virgin and fouled membranes were obtained and analysed to reveal the roughness of the surface which could influence fouling and the surface charge of the membranes were measured through the method of streaming potential at various industrial relevant environments to further elucidate the mechanisms of cell adhesion to the membrane surface. Force measurements were performed to reveal the adhesion force and elasticity values of virgin, process fouled and purposely fouled with the four bacterial isolates, to determine process behaviour in various environmental conditions. Through this research and future work, it is hoped that a rational strategy for economic and effective cleaning processes will be developed which will maintain efficient membrane operation and prolong membrane life, thus enabling the reduction of operating costs of such processes.
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Hausman, Richard. "Development of Low-Biofouling Polypropylene Feed Spacers for Reverse Osmosis". University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1320891800.
Testo completo
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Robinson, Roderick Q. "Desalination of groundwater using reverse osmosis coupled to a windmill". Thesis, Robinson, Roderick Q. (1990) Desalination of groundwater using reverse osmosis coupled to a windmill. Masters by Research thesis, Murdoch University, 1990. https://researchrepository.murdoch.edu.au/id/eprint/52405/.
Testo completoAbstract (sommario):
Reverse osmosis (RO) has the potential to fulfill the requirements of reliability, small size and low energy input suitable for remote area drinking water desalination by linking this technology to a standard multi-vane windmill pump. The research contained in this Masters thesis covers the design, construction, field testing and performance analysis of a prototype windpowered RO desalination system set up at a site near Murdoch University, Western Australia. The prototype was run from July 1988 for thirteen months, yielding 3348 hours of usable windspeed, direction input data, and desalinated water output data. This data has been analysed and the performance determined for the test site wind regime.
Once performance data was obtained under the measured wind regime, a projection of expected performance using wind data from other areas was constructed to establish the performance of the system in remote settings. The performance projection is based on a production model using variables measured during the test period, which are quantified and matched to the wind characteristics of any site as determined by its windspeed distribution curve. All data is entered into a spreadsheet programme, which calculates the projected performance.
Fouling by feedwater contaminants represents another area of potential problems in RO desalination. The Masters research seeks to address this problem by investigating fouling, both by a literature review and experimentation. The solution to the problem is to adopt a number of pretreatment systems and design solutions which minimize fouling in RO systems.
The thesis draws together these two areas of investigation to predict the performance and pretreatment requirements for groundwater desalinations in a typical remote setting in Western Australia.
40
Clarke, Daniel. "Stand-alone solar-pv hydrogen energy systems incorporating reverse osmosis". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1750.
Testo completoAbstract (sommario):
The world’s increasing energy demand means the rate at which fossil fuels are consumed has increased resulting in greater carbon dioxide emissions. For many small (marginalised) or coastal communities, access to potable water is limited alongside good availability of renewable energy sources (solar or wind). One solution is to utilise small-scale renewably powered stand-alone energy systems to help supply power for everyday utilities and to operate desalination systems serving potable water (drinking) needs reducing diesel generator dependence. In such systems, on-site water production is essential so as to service electrolysis for hydrogen generation for Proton Exchange Membrane (PEM) fuel cells. Whilst small Reverse Osmosis (RO) units may function as a (useful) dump load, it also directly impacts the power management of stand-alone energy systems and affects operational characteristics. However, renewable energy sources are intermittent in nature, thus power generation from renewables may not be adequate to satisfy load demands. Therefore, energy storage and an effective Power Management Strategy (PMS) are vital to ensure system reliability.
This thesis utilises a combination of experiments and modelling to analyse the performance of renewably powered stand-alone energy systems consisting of photovoltaic panels, PEM electrolysers, PEM fuel cells, batteries, metal hydrides and Reverse Osmosis (RO) under various scenarios. Laboratory experiments have been done to resolve time-resolved characteristics for these system components and ascertain their impact on system performance. However, the main objective of the study is to ascertain the differences between applying (simplistic) predictive/optimisation techniques compared to intelligent tools in renewable energy systems. This is achieved through applying intelligent tools such as Neural Networks and Particle Swarm Optimisation for different aspects that govern system design and operation as well as solar irradiance prediction.
Results indicate the importance of device level transients, temporal resolution of available solar irradiance and type of external load profile (static or time-varying) as system performance is affected differently. In this regard, minute resolved simulations are utilised to account for all component transients including predicting the key input to the system, namely available solar resource which can be affected by various climatic conditions such as rainfall. System behaviour is (generally) more accurately predicted utilising Neural Network solar irradiance prediction compared to the ASHRAE clear sky model when benchmarked against measured irradiance data. Allowing Particle Swarm Optimisation (PSO) to further adjust specific control set-points within the systems PMS results in improvements in system operational characteristics compared to using simplistic rule-based design methods. In such systems, increasing energy storage capacities generally allow for more renewable energy penetration yet only affect the operational characteristics up to a threshold capacity. Additionally, simultaneously optimising system size and PMS to satisfy a multi-objective function, consisting of total Net Present Cost and CO2 emissions, yielded lower costs and carbon emissions compared to HOMER, a widely adopted sizing software tool. Further development of this thesis will allow further improvements in the development of renewably powered energy systems providing clean, reliable, cost-effective energy. All simulations are performed on a desktop PC having an Intel i3 processor using either MATLAB/Simulink or HOMER.
41
Dickson, James Morley. "Reverse osmosis transport phenomena in the presence of strong solute-membrane affinity". Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53871.
Testo completoAbstract (sommario):
The reverse osmosis performance of cellulose acetate membranes has been examined and analyzed for several aqueous systems where there is a strong attraction between the organic solute and the membrane material.
The systems investigated included the aromatic hydrocarbons benzene, toluene, and cumene in single-solute aqueous solutions. Six cellulose acetate membranes, modified by annealing at different temperatures, were studied.
Experiments were performed at four pressures (690, 1725, 3450, and 6900 kPa) and at several concentrations (in the range 5 to 260 ppm). The results were found to be markedly different than those observed in the absence of strong solute-membrane affinity. In particular, the solute-water separation decreased rather than increased with increasing pressure and the flux decreased with increasing concentration even though low concentrations, with low osmotic pressures, were studied. Qualitatively, the behavior was explained in terms of a porous membrane mechanism with both solute-membrane affinity and solute mobility varying as a function of solute position with respect to the membrane. The observed reduction in flux was expressed by an empirical equation as a function of concentration of solute in the boundary layer.
The experimental results were analyzed quantitatively by several transport models. The irreversible thermodynamics phenomenological transport, solution-diffusion imperfection and extended solution-diffusion relationships generated parameters that were inconsistent with the original formulations of the models. The irreversible thermodynamics Kedem-Spiegler model, solution diffusion model, Kimura-Sourirajan analysis, and the three parameter finely-porous model were functionally unable to represent the data. Only the four parameter finely-porous model and the surface force-pore flow model were consistent with experimental results. From the finely-porous model the partition coefficient was found to be different on the high and low pressure sides of the membrane and this difference was a function of both pore size and solute. For the surface force-pore flow model, the agreement between the model and data was excellent. However, the surface force-pore flow model was considerably more difficult to use.Ph. D.
42
Martinez, Hiroki. "Design of a desalination plant : aspects to consider". Thesis, University of Gävle, Faculty of Engineering and Sustainable Development, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-6995.
Testo completoAbstract (sommario):
One of the main problems our actual society faces is the shortage of water. Despite the great effort made by authorities and researchers, multiple countries with poor economic resources are experiencing serious difficulties derivative of water scarcity. Desalination provides a feasible solution for inland and coastal areas. Through literature and reviewed articles analysis the reader will meet the actual issues regarding designing a desalination plant, and more over with reverse osmosis (RO) processes, which are the main arguments of this work. One of the big deals is the environmental concern when handling the concentrate disposal. Another important point about desalination processes is the increasingly interest in coupling the units with renewable energy sources (RES). The results point out that regardless of the efforts made until today, additional achievement is required in fields such as membrane’s structure materials for RO method, concentrate disposal systems, governmental water policies review and update, and greater distinction researches between brackish water and seawater RO desalination processes. Taking into consideration the previous outcomes it is finally concluded that some particular steps must be accomplished when beginning a desalination plant design.
43
Mane, Pranay P. "RO Process Optimization Based on Deterministic Process Model Coupled with Stochastic Cost Model". Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14486.
Testo completoAbstract (sommario):
A survey performed over existing two pilot-scale and two full-scale RO desalination facilities to study the current status of boron rejection showed a highest rejection 85% leading to permeate boron concentration of 0.52 mg/L, and recent studies predicted a cost increase due to incorporation of boron reduction systems. Mathematical models were developed to study the process performance and related cost implications. The deterministic process model was verified with pilot-scale experiment performed using a single spiral wound module and was later modified to represent the full-scale design options available to meet the required water quality criteria. Then the selected full-scale design options were simulated to predict their performance in terms of recovery and boron rejection.
For cost analysis, to account for uncertainty probability models were developed for stochastic inputs to the cost estimation model and were used with operating parameters from the full-scale simulations to determine the expected total cost of water produced. Later, a sensitivity analysis was performed to observe the effect of change in uncertainty of inputs. Further, the applications of the deterministic process model are suggested.
44
Zhou, Qing-Hua. "Study on reverse osmosis membrane separation of binary organic liquid mixtures". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5810.
Testo completoAbstract (sommario):
There is an increasing interest for the separation of organic liquid mixtures with reverse osmosis primarily due to its great promise in industrial applications. Based on Surface Force-Pore Flow model (SFPF) developed by Matsuura and Sourirajan, the study was conducted with the aid of a computer program, for the separation of organic liquid mixtures by reverse osmosis for the purpose of design and prediction of membrane performance. The results show that for a given separation system the pore size on the membrane surface and the interaction force between the membrane material and solute are two important factors which govern the effectiveness of the membrane separation of organic liquid mixtures.
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Bermudez-Contreras, Alfredo S. "An energy recovery device for small-scale seawater reverse osmosis desalination". Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6098.
Testo completoAbstract (sommario):
This work presents the concept development, implementation and first practical demonstration of a new pressure intensifier for energy recovery in small-scale seawater reverse osmosis systems, and the simplified system configuration it requires. The new concept has great potential to reduce the specific energy consumption of small-scale seawater reverse osmosis systems. A mathematical analysis to study pressure intensifiers for energy recovery in reverse osmosis applications was developed. The analysis was used in the design and modelling of the energy recovery device. A first prototype was built and subsequently demonstrated in a system desalinating seawater over a wide range of electrical input power stretching between 286 and 1196 W, producing up to 286 L/h of freshwater with specific energy consumptions in the range of 3.5 to 4.5 kWh/m^3. The flat specific energy characteristic makes the device attractive for renewable-energy-powered systems without energy storage. The prototype implementation was realised through modifying a Clark pump, but the new concept is fundamentally different. The new device recovers energy from the concentrate stream, which it then uses to suck in and pressurise seawater, relying purely on its piston area ratio, and thus eliminating the need for a low-pressure feed pump.
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Bhujle, Aditya Sarvanand. "Autonomous control and membrane maintenance optimization of photovoltaic reverse osmosis systems". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79332.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from department-submitted PDF version of thesis.
Includes bibliographical references (p. 97-102).
The supply of clean water in remote and off-grid areas has been a major global challenge for humanity. Over 780 million people lack access to clean water [1]. However, a significant fraction of these people have access to undrinkable surface, brackish or sea water. A promising solution to this problem is to use photovoltaic powered reverse osmosis (PVRO) systems to purify this unsafe water to produce clean drinking water. However, high initial capital costs and a lack of commercial viability have prohibited these systems for commercial and daily use. For this approach to be feasible and reach large-scale commercial viability, PVRO systems need to be energy efficient and cost-competitive compared with reverse osmosis systems powered by conventional sources, such as diesel engines or electricity from the grid. The costs and energy consumption in a PVRO system can be significantly decreased by maximizing water production and minimizing the effects of membrane degradation to extend system life. The membrane degradation considered here is the fouling phenomenon in which suspended solids and dissolved substances collect on the surface and within the pores of the membrane thereby reducing its permeability This thesis describes an innovative approach to autonomously controlling and optimizing community scale PVRO systems by controlling membrane degradation due to fouling, using a self-optimizing condition based maintenance algorithm. Additionally, by exploiting the energy compliance of PVRO elements and actively controlling the individual components of the system, water production can be maximized. The compliance in a PVRO system has been found to significantly affect PVRO performance by reducing system efficiency and resulting in long startup delays in producing clean water. In this thesis, a controllable recovery ratio concept system has been presented. By actively controlling the PVRO system, an improvement of 47% over the existing performance of a fixed recovery ratio system has been shown in simulations. Use of condition based maintenance strategies show an improvement of over 10% in cumulative clean water production compared to scheduled quarterly maintenance and 58% over 1 year in cumulative clean water production compared to the case without any maintenance. This is interesting since typical community scale and point of use systems can be and are operated without periodic maintenance [2]. Combining the optimal power control and condition-based maintenance strategies, an improvement in water production of 85 % is shown for a July day in Boston over the MIT PVRO system. Finally, a self-optimizing condition based maintenance algorithm is proposed as the optimal solution to control membrane degradation due to fouling.
by Aditya Sarvanand Bhujle.
S.M.
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Pype, Marie-Laure. "Monitoring reverse osmosis membrane integrity and virus rejection in water reuse". Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20234/document.
Testo completoAbstract (sommario):
Les procédés d'osmose inverse (OI) permettent la production d'eau recyclée de très haute qualité grâce à l'élimination de contaminants organiques et inorganiques et de micro-organismes. Le suivi du bon fonctionnement de ce procédé est nécessaire pour valider la rétention des virus pathogènes afin de protéger la santé des usagers. La présence de minéraux et matières organiques dans les effluents rend inévitable le colmatage des membranes lors de leur fonctionnement et diminue ainsi leur performance. Afin d'éviter et d'éliminer ces colmatages, les stations de traitements des eaux utilisent des produits chimiques. Ces derniers vont modifier les performances globales des membranes en polyamide comme par exemple la diminution de la perméabilité à l'eau, et plus particulièrement les performances de rétention des virus, or l'ensemble de ces perturbations n'est que très peu compris et donc peu maitrisé. L'abattement des virus par l'OI sur des membranes intègres ou modifiées (ex : colmatage) ont donc été déterminés en mesurant la rétention d'un virus modèle de type phage MS2 et de substituts comme les sels (mesurés par conductivité), la rhodamine-WT (R-WT) ou les sulfates. La conductivité est, en effet, la technique de contrôle standard dans les stations de traitement des eaux (échelle industrielle).Le premier objectif de ce travail est d'évaluer l'utilisation d'un autre paramètre, les matières organiques dissoutes (DOM) comme nouveau substitut de virus et de déterminer l'impact du dysfonctionnement des procédés d'OI sur l'abattement des DOM et des sels à l'échelle industrielle. Les DOM peuvent en effet également être utilisées comme indicateur de qualité des eaux en fonction de leurs compositions et de leurs concentrations. L'abattement des DOM est donc testé comme nouvelle technique de surveillance afin de distinguer les fuites des changements de performance des membranes. Il est conclu que les DOM peuvent être utilisées comme nouvelle technique de contrôle. De plus, une variation de l'abattement des DOM peut aider à identifier des fuites de manière plus robuste que par l'abattement des sels. Le deuxième objectif est de déterminer l'effet des défauts membranaires sur les abattements d'un virus modèle (phage MS2) et de quatre substituts (R-WT, DOM, sulfate et sels) à l'échelle de systèmes de laboratoire. Deux systèmes à flux longitudinal est utilisés : une membrane plane et un module à spirale. Dans un premier temps, l'effet du colmatage sur les abattements de ces différents virus et substituts est étudié. Le colmatage organique, créé en utilisant un mélange de matières organiques, a pour effet d'augmenter de plus de 0,1 log les abattements de la R-WT, des sels et des DOM. Cette augmentation générale peut être due au blocage des cavités de la membrane et/ou par la sorption des substituts sur les matières organiques.Le colmatage inorganique, créé en utilisant un mélange de sels, n'a pas d'effet sur le rejet des substituts sauf pour les sels qui montre un comportement différent entre les deux systèmes. Dans le système à membrane plane, la couche inorganique permet d'augmenter le passage des sels à travers la membrane. Par opposition, il n'y a pas d'effet sur leur abattement avec le module à spirale. Cette variation entre les deux systèmes peut être causée par la différence de configuration (module à spirale contre membrane plane). Dans un deuxième temps, l'effet du chlore (modes passif et actif) sur la rétention de ces cinq composés est mesuré. Après un contact de 9000 ppm.h de NaOCl à pH 7, la surface membranaire change chimiquement. La formation de liaison Cl dans la couche en polyamide et la rupture des liaisons NH provoquent l'augmentation de la perméabilité à l'eau et diminuent l'abattement de l'ensemble des substituts. Malgré une forte diminution de 1,2 log de l'abattement en sel, l'abattement minimum du phage MS2 reste de 3 logOne of the major applications of reverse osmosis (RO) process is the production of high quality recycled water by providing a barrier to remove organic and inorganic contaminants as well as pathogens including viruses. In order to protect public health, validation and monitoring of the RO process integrity are necessary to ensure its correct operation. During operation a certain degree of fouling is inevitable and can reduce RO membrane performance. Thus, chemicals are often used in water treatment plants to prevent or remove the membrane fouling. However, these chemicals can modify the integrity of the polyamide layer on RO membrane overtime. Up-to-date, the impact of membrane's physical change on its virus removal efficiency cause by the chemical use during operation is still not well understood.A minimum virus removal efficiency of intact and impaired (e.g. by fouling) RO membranes can be ascertained by measuring the rejection of MS2 phage and virus surrogates such as salt as measured by conductivity, rhodamine-WT (R-WT) or sulphate. However, conductivity measurement is the only full-scale standard monitoring technique. The removal of dissolved organic matter (DOM), which has been used as an indicator of water quality, can possibly be used for this purpose.The first objective of this work was to assess the suitability of DOM as a virus surrogate and to determine the impact of process failure on salt and DOM rejection in full-scale plants. A change of the conductivity does not necessarily mean that the membrane integrity has been breached. Thus, DOM monitoring has been tested and combined with the conductivity monitoring in order to distinguish between leaks and changes in membrane performances. It was concluded that DOM could be used as new monitoring technique. Moreover, a variation of DOM rejection can help identifying leaks better than just conductivity profiling alone.The second objective was to determine the effect of membrane impairments on the rejection of one model virus (MS2 phage) and four virus surrogates (R-WT, DOM, sulphate and salt) using lab-scale RO set-ups. To this aim, two different cross-flow set-ups were used: a flat-sheet and a single 2.5” spiral-wound module.Firstly, the effects of organic fouling and scaling on the rejection of model virus and virus surrogates were studied separately. Organic fouling was created using a mix of organic foulants. The result of this study showed an increase of the rejection by more than 0.1 log for R-WT, salt and DOM. The general increase of the surrogates' rejection might be due to the blocking of cavities of the polyamide membrane and/or to the sorption of surrogates to the fouling layer, which was observed by different autopsy techniques.Scaling was created using a mix of inorganic salts in order to reconstitute the composition of a RO feed water and avoiding the presence of organic foulants. Scaling was found to have no impact on the rejection of all tested virus surrogates except for salt. Salt rejection showed a change of behaviour between different set-ups: with the 2.5” module set-up the inorganic layer led to a stabilisation of the salt rejection, whereas the salt rejection increased with the flat-sheet set-up. This could be explained by the variations of the systems configuration (i.e. spiral module versus flat-sheet, feed spacer height, etc.).Secondly, the long-term impact of membrane ageing by exposure to chlorine, either active under filtration or passive by soaking, on the rejection of the model virus and four surrogates was studied. After a contact time of 9000 ppm∙h NaOCl at pH 7, the membrane surface chemistry changed. The introduction of chlorine in the membrane chemistry and the breakage of amide bonds caused an increase of the water permeability and a decrease of the model virus and virus surrogates rejection
48
Martinetti, C. Riziero. "Membrane contractor processes for desalination of brackish water reverse osmosis brines /". abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1455665.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Nevada, Reno, 2008."May, 2008." Includes bibliographical references (leaves 35-38). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
49
Ghiu, Silvana Melania Stefania. "Mass Transfer of Ionic Species in Direct and Reverse Osmosis Processes". [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000176.
Testo completo
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Soliz, Deserié H. "Production of the Forage Halophyte Atriplex lentiformis on Reverse Osmosis Brine". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202737.
Testo completoAbstract (sommario):
Throughout the arid and semi-arid regions, researchers have been looking at different ways to deal with the salinity problem of the soil and water as well as feed for the livestock. Study 1 focused on a pilot project conducted in an irrigation district in Marana, AZ, USA, looking at using Reverse Osmosis (RO) concentrate on Atriplex lentiformis (quailbush) and then harvesting the plant to be tested for its possible use as a supplement in feed for livestock. Three irrigation treatments were tested based on the potential evapotranspiration rate (ET(o)): (1) plots irrigated at ET(o) adjusted daily via an on-site micrometeorology station; (2) plots irrigated at 1.5 ET(o) adjusted daily; (3) plots irrigated at a constant rate throughout the year based on the mean of annual ET(o). The plants produced 15-24 tons ha⁻¹ year⁻¹ of biomass and could be irrigated at the rate of ET(o), ca. 2 m yr⁻¹ at this location. It was concluded that irrigation of halophyte forage crops provide a viable strategy for extending water supplies and disposing of saline water in arid-zone irrigation districts. Study 2 focused on a field data from Study 1 and two greenhouse experiments. The greenhouse experiments were conducted in 2007 and 2010. The 2010 greenhouse trials, under well-watered conditions, showed that the apparent zero-point-salinity for yield was 47.3 g L⁻¹ TDS. An additional greenhouse experiment was conducted in which plants in sealed pots were grown to the wilting point on a single application of water. The experiment was conducted at different salinities to see if salinity and water stress were additive factors in reducing yield and Water Use Efficiency (WUE). To the contrary, yield and WUE actually increased as a function of salinity, perhaps due to conversion from C3 to C4 photosynthesis over the salinity range (noted in other studies with A. lentiformis). We conclude that xerohalophytes such as A. lentiformis could greatly extend the useful range of salinities under which forage crops can be grown in arid-zone irrigation districts.