Tesi: "Membrane treatments"

1

Pinos, Vélez Verónica Patricia. "Development and optimization of catalytic membrane reactors for wastewater treatments". Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/365578.

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Es van obtenir diferents reactors catalítics de membrana (RCM) de membrana de fibra buida de Corindó i nanopartícules de Pd obtingudes per diferents metodologies: humitat incipients impregnació, polvorització catòdica, microemulsió i aliatge amb coure pel mètode de Poliol. RCMs es van provar en medi aquós, pressió ambiental i temperatura o 60 c en generació in situ de peròxid d'hidrogen, l'oxidació i hidrogenació de fenol i ibuprofè i reducció de Cr (VI). La RCM ha actuat com interfície catalítica per tal d'activar l'hidrogen i que reaccione amb oxigen o compost orgànic o inorgànic. La RCM impregnada amb Pd és l'única que van mostrar activitat i tests d'estabilitat. Aquest comportament es va deure a la presència d'àtoms i grups de Pd. La manca activitat de la resta de catalitzadors amb Pd es va deure a la formació d'hidrur de Pd en les condicions de reacció.
Se obtuvieron diferentes reactores catalíticos de membrana (RCM) desde membranas de fibra hueca de corindón y nanopartículas de paladio obtenidas por diferentes métodos: Impregnación a humedad incipiente, sputtering, microemulsion y aleación con cobre por el método del poliol. Los RCM fueron probados en medio acuoso, presión ambiental y temperatura ambiente o 60C en la generación in situ de peróxido de hidrógeno, oxidación e hidrogenación de fenol e ibuprofeno y reducción de Cr(VI). Los RCM actuaron como interfaz catalítica para que el hidrógeno se active y reaccione con el oxígeno o el compuesto orgánico o inorgánico. Los RCM con paladio por impregnación fueron los únicos que presentaron actividad y estabilidad en las pruebas. Este comportamiento se dio gracias a la presencia de átomos y clusters de paladio. La falta de actividad de los otros catalizadores de paladio se debió a la formación de hidruro de paladio en las condiciones de reacción.
Different catalytic membrane reactors (CMRs) were obtained from hollow fiber membranes corundum and palladium nanoparticles obtained by different methods: Incipient wetness impregnation , sputtering , microemulsion and copper alloy by the method of the polyol. The CMRs were tested in aqueous medium, ambient pressure and ambient temperature or 60C for the in situ generation of hydrogen peroxide, oxidation and hydrogenation of phenol and ibuprofen and reduction of Cr(VI). The catalytic CMR acted as interface for the reactions between hydrogen with oxygen or organic or inorganic compound. Only the CMRs with palladium by impregnation were actives and stabilites during the tests. This behavior occurred thanks to the presence of clusters and single atoms of palladium. The lack of activity of the other kind of palladium catalysts were due to the formation of palladium hydride in the reaction conditions.

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2

Wu, Hong. "Sulfate radical based ceramic catalytic membranes for water treatments". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2382.

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The discharge of antibiotics into natural aquatic environment without proper treatments results in the propagation of antibiotics-resistant strains. Effective remediation technologies are therefore urged to remove those emerging contaminants from water. However, antibiotics are difficult to be degraded through a traditional biological treatment because they would deactivate the effective bacteria used in the process. Advanced oxidation processes (AOPs) using highly reactive oxygen species (ROS) such as hydroxyl radicals ( OH) and sulfate radicals (SO4 •− • ) have been widely employed as an efficient way for antibiotics degradation owing to the high oxidation ability, non-selectivity and low cost. However, the recovery of the suspended catalysts after use is the biggest obstacle for the wide application. Meantime, membrane separation has also been extensively applied as a promising wastewater treatment technology with the advantages of long-term operation, low energy consumption and high yield of production. The membrane fouling is, however, a critical issue restricting the widespread application of membrane. For addressing above-mentioned issues, with extensive technological and scientific endeavours, this PhD study focused on the development of novel integration technology of AOPs and membrane separation for antibiotics degradation. In this research, heterogeneous AOPs processes coupled with independent membrane separation unit for suspended catalysts recovery were studied. Moreover, metal oxide based-catalytic membrane for concurrent AOPs and membrane separation were investigated. Firstly, boron, nitrogen co-doped carbon nanotubes supported FeOOH (FeOOH@BNC) was synthesized for the degradation of sulfamethoxazole (SMX) by Fenton-like reaction. The as-synthesized FeOOH@BNC showed an excellent performance in SMX removal (Chapter 3). Secondly, boron, nitrogen co-doped nanotubes (BNC) were developed. The BNC nanotubes with a high specific area, abundant active sites, and controllable N–B–C structures demonstrated prominent peroxymonosulfate (PMS) activation ability towards 4-hydroxylbenzoic acid (HBA) degradation (Chapter 4). It was also found that both FeOOH@BNC and BNC suspended catalysts in the treated solution can be well recovered via membrane filtration (Chapter 3 and 4). Finally, two metal oxide-based catalytic ceramic membranes (Co3O4@CM and MnO2@CM) were prepared via a simple one-step ball-milling method with a high temperature sintering. The as-prepared Co3O4@CM and MnO2@CM composite catalytic membranes were characterized and tested for the degradation of aqueous HBA solution by SR-AOPs procedure. It was found that the composite membranes showed excellent HBA removal efficiencies, good reusability and high anti-fouling performances (Chapter 5 and 6). Mechanistic studies, e.g. materials chemistry, generation of reactive radicals, and degradation pathways, were also carried out. The developed catalysts, catalyst membranes, and the combined processes as well as the mechanistic studies are expected to provide significant contributions in terms of both technology and scientific knowledge to remediation of emerging contaminants.

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3

Gandi, Ravikishor. "Treatments of hemi caustic and extractives streams". Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44781.

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Disposal of effluent from pulp and paper industry is one of the major problems faced by entrepreneur in view of increasing environmental standards day by day. In addition to this, industry loses economic value by disposing the effluent or selling it for a low price to other industries. Therefore, to address this problem, in the present study, 2 pulp mill effluents were selected to recover the economic value namely Hemi caustic stream and brown stock filtrate. As far as the recovery of value of hemi caustic stream is concerned, freeze concentration technique was used to recover water in its pure form and membrane separation was used to separate hemi cellulose from effluent so that permeate can be used as a pure source of caustic elsewhere. In addition to this, hemi caustic stream was subjected to acid hydrolysis to convert hemi cellulose into sugars. These sugars can be used to produce bioethanol. As far as the recovery of values of brown stock filtrate is concerned, it was proposed to recycle brown stock filtrate as a source of washing water for brown stock washers in the mill. However, continuous recycling of brown stock filtrate into the process causes building up of extractives in the recycle stream which in turn might deposit on the pulp and affects the quality of the pulp. Therefore, it was decided to separate extractives from the brown stock filtrate before recycle it into the mill. Dissolved Air flotation technique was used to achieve the above mentioned objective. An attempt was made to develop an improved and most reliable version of existing extractives measurement method to quantify the performance of Dissolved air flotation technique.

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4

Yu, Feiran. "Physicochemical Modifications of Milk Fat Globule Membrane Proteins During Temperature Processing of Milk". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534770720065921.

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5

Francis, A. "The effects of ageing and low temperature pre-sowing treatments on the membrane status and germination performance of tomato seeds". Thesis, University of Bedfordshire, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304311.

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6

Maxwell, Deborah. "REMEDIATION OF HEAVY METAL CONTAMINATION IN SEDIMENTS: APPLICATION OF IN SITU TREATMENT UTILIZING EMULSIFIED LIQUID MEMBRANE AN". Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4329.

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Heavy metal contamination of soils, sediments and groundwater presents an ongoing source of hazardous and persistent environmental pollution. How best to remediate these contaminants is the impetus of continuing research efforts. Methods include containment, ex situ and in situ techniques. A successful in situ method utilizing a combination of emulsified liquid membranes, ELM, and zero-valent metal, ZVM, and bimetals has demonstrated impressive heavy metal reduction in 100 ppm solutions of Cd, Cu, Ni, Pb, Cr and U. This promising in situ method has been employed by the Industrial Chemistry Laboratory at the University of Central Florida and it has demonstrated considerable success in treating several environmental threats. Contaminated soils, surfaces, sediments and groundwater with offending agents such as trichloroethene, polychorobiphenyls and heavy metals have been treated utilizing emulsified liquid membrane systems containing zero-valent iron or bimetal particles. In vial studies, lead spiked sediments have shown repeatable 60% removal of lead after seven days of treatment. A persistent pattern emerged at ten days whereupon remediation levels began to drop. The current study was established to determine the reason for the decline at ten days and beyond. Questions addressed: Does the formation of an impeding oxide layer diminish the remediation capacity of the iron/magnesium system? Does the emulsion reach a maximum capacity to withdraw the contaminant? Do the soil components or the soil structure interfere with the access to the contaminant? This study has yielded insight into the reasons emulsified liquid membrane systems containing zero-valent metals achieved maximum lead removal at day seven, and thereafter begin to lose their effectiveness. A three part study was implemented to address and to answer the three questions pertaining to the consistent pattern of diminishing remediation levels exhibited at day ten and beyond. Initially, from Study I results it appeared that the formation of an impeding oxide layer on the bi-metal which was inside the emulsion droplet and which plated or precipitated with the lead was not occurring at day ten. Results indicated that the iron/magnesium was still capable of removing lead. Furthermore, from Study II results the emulsion dose injected appeared adequate to remove the lead, meaning that the emulsion had not reached its maximum capacity for remediation. The emulsion dose was not a limiting factor. Lastly, Study III results seemed to indicate that the drop in remediation after day seven pertained to the soil structure. There appeared to be some merit to the idea that with aging of the sediment, the lead was diffusing and migrating to some inaccessible interior sites within the sediment particles. Additionally, indications from day ten and day fourteen delineated that a second emulsion dose injection might restore lead removal levels to approach those first observed at day seven and consequently be a useful field application. In order to explore the effectiveness of injecting a second dose of emulsion, another vial study was implemented. The typical pattern of observing sixty percent maximum lead removal at day seven was observed. In separate groups, a second injection of emulsion was added at day five, and then for another vial series, a second dose was added at day seven. The second emulsion dose treatment for either day five or day seven did not yield any increases in percent lead removal. Another theory emerged after viewing micrographs of recovered iron/magnesium compared with fresh ball-milled bimetal. In addition, scanning electron microscopy appeared to confirm the explanation that the emulsified zero-valent metal system might be compromised after day seven. This would lead to exposure of the iron/magnesium to the air and the elements. Corrosion of the bimetal might be occurring. With time, release of the plated or precipitated lead back into the sediment mixture could follow. The results of Study I had led to the conclusion that an impeding oxide layer had not formed; however, this conclusion may have been premature because the recovered iron/magnesium was exposed to lead solution in the vial study. Perhaps if the recovered iron/magnesium was inserted back into an emulsion and injected into lead spiked sediments the percent lead removed might give a more accurate picture of the iron/magnesium's capability to continue performing remediation. Remediation of sediments contaminated with lead is a complicated task because of the complex nature of sediment components. Emulsified liquid membranes utilizing zero-valent bimetals has repeatedly demonstrated impressive results at day seven; however, this treatment method is not without its limitations. Optimal results appear to be gained at day seven after emulsion injection. The bimetal and plated or precipitated lead must be removed at that point; otherwise the effective remediation of the contaminant is progressively reversed.
M.S.
Department of Chemistry
Sciences
Industrial Chemistry MS

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7

Osborn, Shawn James. "Morphological and Mechanical Properties of Dispersion-Cast and Extruded Nafion Membranes Subjected to Thermal and Chemical Treatments". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/37517.

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The focus of this research project was to investigate morphological and mechanical properties of both extruded and dispersion-cast NafionÂ® membranes. The project can be divided into three primary objectives; obtaining a fundamental understanding of the glass transition temperature of NafionÂ®, determining the effect of thermal annealing treatments on the morphology and mechanical properties of dispersion-cast NafionÂ®, and examination of dispersion-cast NafionÂ® subjected to an ex-situ, Fentonâ s chemical degradation test. NafionÂ®, a perfluorosulfonate ionomer, is considered a commercially successful semi-crystalline ionomer with primary applications in chlor-alkali cells and proton exchange membrane fuel cells. With the aid of dynamic mechanical analysis (DMA) and dielectric spectroscopy (DS), we were able to provide definitive evidence for a genuine glass transition in NafionÂ®. DMA of NafionÂ® samples that were partially neutralized with tetrabutylammonium counterions showed a strong compositional dependence suggesting that the Î²-relaxations of H+-form NafionÂ® and the neutralized ionomers have the same molecular origin with respect to backbone segmental motions. Building upon our previous studies of the molecular and morphological origins of the dynamic mechanical relaxations of NafionÂ® neutralized with a series of organic ions, the glass transition temperature of H+-form NafionÂ® is now confirmed to be the weak Î²-relaxation centered at -20 Â°C. Dielectric spectra also showed this transition from the perspective of dipole relaxation. The signature of cooperative long range segmental motions in dielectric spectra was seen here, as with other polymers, mainly through the excellent agreement of the Î²-relaxation time-temperature dependence with the Vogel-Fulcher-Tammann equation. We have also discovered that new dispersion-cast H+ form NafionÂ® membranes are susceptible to disintegration/dissolution when subjected to boiling methanol. In this work, we have achieved significant decreases in the percent solubility of H+-form NafionÂ® by either thermally annealing above 175 Â°C or solution-processing at 180 Â°C using a high boiling point solvent. Small Angle X ray Scattering (SAXS) displayed a change in the morphology of H+ form membranes with increasing annealing temperature by a shift in the crystalline scattering peak (q â 0.05 Ã 1) to lower q values. Counterion exchange of NafionÂ® from H+ to Na+ form had no influence on the membraneâ s susceptibility to disintegration in boiling methanol. In order to achieve mechanical stability in boiling methanol, Na+ form membranes had to be annealed at 275 Â°C for at least fifteen minutes. The SAXS data of annealed Na+ form membranes showed a dramatic decrease in crystalline order with annealing temperature, ultimately leading to the disappearance of the crystalline scattering peak after fifteen minutes at 275 Â°C. The onset of methanol stability with the melting of NafionÂ® crystallites suggests that chain entanglement is an important parameter in obtaining solvent stability. With respect to chemical stability, we performed studies aimed at examining the effects of Fentonâ s Reagent on the resistance to radical attack of new generation, dispersion-cast NafionÂ®. Changes in the 19F solid-state NMR spectra of dispersion-cast NafionÂ® before and after chemical degradation via Fentonâ s Reagent predicts a rather random attack by â ¢OH and â ¢OOH radicals. Several membranes were also thermally annealed between 100-250 Â°C in an attempt to correlate crystallinity with chemical degradation kinetics of NafionÂ® via Fentonâ s Reagent. The results indicate that the effect of counterion exchange into the Na+ form was minimal, but the degree of thermal degradation had a tremendous effect on the fluoride release rate and chemical degradation kinetics. By exchanging the membranes into the Na+ form, thermal degradation was avoided, allowing us to study the role of crystallinity as a function of fluoride release. Ultimately, NafionÂ® crystallinity was deemed an important factor in deterring peroxide radical attack. As the percent crystallinity decreased with annealing temperature, the fluoride concentration in the resulting Fentonâ s media increased accordingly, indicating that the amorphous regions of the polymer are more susceptible to chemical degradation via peroxide radical attack.
Ph. D.

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8

MANIGAS, LUISA. "Use of membrane bioreactors for the bioremediation of groundwater polluted by chlorinated compounds". Doctoral thesis, Università degli Studi di Cagliari, 2008. http://hdl.handle.net/11584/265895.

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The aim of this experimental work has been the application of a new polluted waters treatment technology for the selection of a bacterial population capable of bioremediating a synthetic groundwater polluted by four different chlorinated compounds. The innovative technology applied in this study was the biological treatment system known as MSBR (Membrane Sequencing Bioreactor), which consists of a Sequencing Batch Reactor (SBR) coupled to a membrane module for the filtration of the biological sludge that degrades the chlorinated compounds present in the polluted water fed to the system. The synthetic groundwater used in this experimentation contained four chlorinated compounds: 1,2-dichloroethane, 1,2-dichlorobenzene, 2-chlorophenol and trichloroethylene. During the development of the research, the chlorinated compounds were fed either alone on in different mixtures in order to identify possible effects of each substrate on the degradability of the others. Some operational parameters were varied in order to check the possibility of implementing the system at a larger scale. The MSBR system equipped in this study was effective in the acclimation of a sludge to hardly biodegradable xenobiotic compounds, and the degradation rates achieved were comparable to other similar studies performed, even if in this experimentation, differing from all the others found in literature, good removal rates were achieved for the degradation of the substrates when they were fed in mixtures.

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Wagh, Priyesh Ashokrao. "SYNTHESIS OF BIOLOGICALLY-INSPIRED NANOFILTRATION MEMBRANES USING PROTECTED, MUTATED, AND SIMULATED AQUAPORINS". UKnowledge, 2018. https://uknowledge.uky.edu/cme_etds/92.

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Gram-negative bacterial cells are surrounded by a cell membrane which protects the cell and controls the transport of nutrients and waste products in and out of the cells at a fast rate. This rapid transport of nutrients and wastes through the cell membrane is made possible by channel proteins called porins. Various types of porins present in the cell membrane have specific functions depending on their selectivity towards different nutrients, and channel proteins selective towards water are called aquaporins. These proteins restrict the passage of all entities except water molecules and they provide a fast transport rate of water molecules at 109 molecules/second per channel. The high selectivity of porins has led to their incorporation into synthetic systems, and one example is the addition of porins to separations membranes in order to enhance their performance in terms of selectivity and permeability, in a field called biomimetics. The concept of incorporating aquaporins into synthetic membranes has been studied for the last 10 years in order to enhance the water permeability and selectivity of membranes for water purification; however, there are still limitations such as high costs, difficulties in fabrication of aquaporins, their alignment into synthetic membrane assembly, low stability, and limitations on number of aquaporin molecules that can be introduced into synthetic membranes limit their applicability. In recent years, concurrent with the work on aquaporin-based biomimetic membranes, there has been an increase in the study of synthesizing molecules with similar structure-function relationships of aquaporins. These artificial channels attempt to mimic the high-water permeability and selectivity of aquaporins, while being synthesized using simple chemistry, being solvent compatible, and requiring less space on the membrane surface which helps to incorporate more channels into the membrane assembly. The objectives of this study were to first incorporate aquaporins into synthetic nanofiltration membranes without chemical alteration them to prevent flattening or denaturing of aquaporins; then, the second objective was to install functional groups on aquaporins and align them in the direction of water flow; lastly, the third objective was to synthesize artificial channels in order to overcome the issues with aquaporin stability, alignment, and efficient packing of water channels onto the membrane surface. For the first objective, aquaporins were treated with a polysaccharide, gum Arabic, and incorporated into an amphiphilic polymer, polyvinyl alcohol with alkyl side chains (PVA-alkyl), in order to simulate the natural housing of lipid bilayer for aquaporins and to protect them from denaturing. Long alkyl chains provided the hydrophobic component, while PVA provided the hydrophilic component of the amphiphilic polymer. Membranes modified with aquaporins displayed lower flux declines and higher flux recoveries after reverse flow filtration, along with improved rejection values for both protein and salt solutions as compared to PBI and PBI-PVA-alkyl membranes. However, there was leakage of ions between channels. Therefore, in order to improve the rejection of protons, ions and other impurities, the channels were aligned with the direction of water flow. Functional groups were installed on Aquaporins using site-directed mutagenesis for covalent attachment to the polymer matrix so that the proteins could be immobilized to the membranes and aligned in the direction of the flow. Aquaporin constructs were modified to bear affinity tags or unique amino acids at the N-terminus of the aquaporin molecule, which was used to facilitate directional immobilization. Each aquaporin monomer was modified with a unique amino acid Cys group at the N-terminus right after the first Met, and due to the aquaporin tetrameric nature, these Cys groups became four anchors for attachment. The presence of these four Cys anchors per aquaporin tetramer was used to attach on the membrane surface in alignment with the feed water flow direction. Membranes modified with mutated aquaporins showed consistently higher salt rejection values of ~70% irrespective of feed concentration, along with higher flux recoveries and lower flux declines. Commercial NF-270 membranes provide a monovalent salt (NaCl) rejection of ~50% and divalent salt (MgCl2) rejection of 97%. Also, approximate coverage of membrane surface with attached aquaporins was calculated using simulation studies. Simulation studies showed that immobilized aquaporins with PVA-alkyl provided a diffusion rate equivalent to 64% coverage on the membrane surface. This showed that aquaporins didn’t cover the entire surface area of the membrane. However, immobilized aquaporins were responsible for the rejection of a portion of ions passing through the membrane. In order to overcome the limitations of aquaporin incorporation into polymer membranes, artificial organic frameworks were added as surface modification on PBI membranes. Organic frameworks were synthesized as derivatives of hybrid bisamides. The series of bisamides 1-4 consist of 6-amino-pyridine-2-dicarboxylic acid, 6-hydroxymethyl-pyridine-2-carboxylic acid and ethylenediamine, trimethylenediamine, putrescine, and cadaverine depending on the length of carbon chain. These frameworks are amphiphilic in nature and have strong chemical attachment due to the presence of amines and carboxylic acids into each building block. These molecules were introduced into the membrane matrix using carbodiimide chemistry. FTIR results showed the attachment of these bisamide molecules onto the surface of a modified PBI membrane. Also, modified membranes showed a reduced molecular weight cut off (MWCO) for neutral organic molecules. Overall, membranes modified with aquaporins have shown a potential to provide consistently high salt rejections with increasing feed solutions. Also, preliminary results have shown that bisamide molecules can be attached onto the membrane surface as organic frameworks and have a potential to be an alternative for aquaporins based biomimetic membranes.

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Timoteo, J?nior Jos? Fl?vio. "Membrana de alumina an?dica: comportamento da microestrutura e estudo das propriedades ?pticas ap?s tratamento t?rmico". Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12798.

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Thin commercial aluminum electrolytic and passed through reactions was obtained with anodic alumina membranes nanopores. These materials have applications in areas recognized electronic, biomedical, chemical and biological weapons, especially in obtaining nanostructures using these membranes as a substrate or template for processing nanowires, nanodots and nanofibers for applications noble. Previous studies showed that the membranes that have undergone heat treatment temperature to 1300? C underwent changes in morphology, crystal structure and optical properties. This aim, this thesis, a study of the heat treatment of porous anodic alumina membranes, in order to obtain and to characterize the behavior changes structures during the crystallization process of the membranes, at temperatures ranging between 300 and 1700? C. It was therefore necessary to mount a system formed by a tubular furnace resistive alumina tube and controlled environment, applying flux with special blend of Ag-87% and 13% N2, in which argon had the role of carrying out the oxygen nitrogen system and induce the closing of the pores during the densification of the membrane. The duration of heat treatment ranged from 60 to 15 minutes, at temperatures from 300 to 1700? C respectively. With the heat treatment occurred: a drastic reduction of porosity, grain growth and increased translucency of the membrane. For the characterization of the membranes were analyzed properties: Physical - thermogravimetric, X-ray diffraction, BET surface area; morphological - SEM, EDS through compositional and, optical absorbance, and transmittance in the UV-VIS, and FTIR. The results using the SEM showed that crystallization has occurred, densification and significant changes in membrane structure, as well as obtaining microtube, the BET analysis showed a decrease in specific surface area of the membranes has to 44.381 m2.g-1 to less than 1.8 m2.g-1 and in the analysis of transmittance and absorbance was found a value of 16.5% in the range of 800 nm, characteristic of the near infrared and FTIR have confirmed the molecular groups of the material. Thus, one can say that the membranes were mixed characteristics and properties which qualify for use in gas filtration system, as well as applications in the range of optical wavelength of the infra-red, and as a substrate of nanomaterials. This requires the continuation and deepening of additional study
L?minas delgadas de alum?nio comercial passaram por rea??es eletrol?ticas e obtiveram-se membranas de alumina an?dica com nanoporos. Estes materiais t?m reconhecidas aplica??es nas ?reas eletr?nicas, biom?dicas, qu?micas e biol?gicas, principalmente, na obten??o de nanoestruturas utilizando estas membranas como substrato ou molde para processamento de nanofios, nanopontos e nanofibras para aplica??es nobres. Estudos anteriores apontaram que as membranas que passaram por tratamentos t?rmicos at? a temperatura de 1300? C, sofreram altera??es na morfologia, na estrutura cristalina e nas propriedades ?pticas. O objetivo deste trabalho foi o estudo do tratamento t?rmico de membranas de alumina an?dica porosas, com o intuito de obter e caracterizar as altera??es de comportamento das estruturas, durante o processo de cristaliza??o das membranas, em temperaturas que variaram entre 300 e 1700? C. Assim, foi necess?rio montar um sistema formado por um forno resistivo tubular e tubo de alumina com ambiente controlado, aplicando fluxo com mistura especial de Ar-87% e N2-13%, no qual o arg?nio teve o papel de carrear o oxig?nio para fora do sistema e o nitrog?nio de induzir o fechamento dos poros, durante a densifica??o das membranas. A dura??o dos tratamentos t?rmicos variou de 60 a 15 minutos, para as temperaturas de 300 at? 1700? C respectivamente. Com o tratamento t?rmico ocorreu redu??o dr?stica da porosidade, crescimento do gr?o e aumento da translucidez da membrana. Para a caracteriza??o das membranas, foram feitas an?lises das propriedades: f?sica - termogravim?trica; difra??o de raios-X, ?rea superficial BET; morfol?gica - MEV, composicional atrav?s do EDS; e, ?ptica - transmit?ncia e absorb?ncia no UV-VIS e FTIR. Os resultados por meio do MEV mostraram que ocorreu cristaliza??o, densifica??o e mudan?as significativas na estrutura das membranas, bem como, a obten??o de microtubo; a an?lise de BET constatou uma diminui??o na ?rea superficial espec?fica das membranas que passou de 44,381m2.g-1, para menos de 1,8m2.g-1; na an?lise de transmit?ncia e absorb?ncia foi encontrado um valor de 16,5 % na faixa de 800nm, caracter?stico do infravermelho pr?ximo e no FTIR foram confirmadas os grupos moleculares do material. Assim, pode-se afirmar que as membranas apresentaram caracter?sticas mistas e propriedades que as qualificam para o uso em sistema de filtra??o de gases, bem como, de aplica??es ?ticas na faixa do comprimento de onda do Infravermelho, e como substrato de nanomateriais. Isto requer a continuidade e aprofundamento em estudos complementares

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Chung, Kyung Sun. "Membrane Distillation for Leachate Treatment with Fenton Pre-Coagulation Treatment Process". Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/96701.

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Landfill leachate is considered as a complex wastewater with various organic and inorganic species which must meet strict discharge standards before its release. Due to such high concentration of diverse pollutants, leachate is low in biodegradation; therefore, a proper usage of physicochemical treatments is required. In this study, membrane distillation (MD) has been used along with Fenton treatment process for pre-coagulation to achieve an effective removal of contaminants. MD is a technology derived with vapor pressure difference across the hydrophobic membrane which traps the feed-wastewater vapor at the entrance of the hydrophobic side before permeation. In order to modify and assist in membrane technology's common drawback, which is dealing with foulants, Fenton oxidation is coupled in the leachate treatment process. Fenton is reserved to be the most effective for leachate treatment and is widely used due to its simple operation and low costs. Fenton oxidation was able to lessen the chemical oxygen demand (COD) concentration of leachate up to 55% while increasing the conductivity and reducing the concentration of NH4-N. The membrane flux and volume had a significant increase with a use of lower COD leachate after Fenton treatment coupled with MD.
Master of Science
Landfilling has been recognized as a principal disposal process of municipal solid wastes globally over the past decades, and this disposal method has been one of the leading concerns for a continuous production of landfill leachate. Leachate is considered as a complex wastewater with a variety of organic and inorganic species which must meet strict discharge standards before its release. Due to such high concentration of diverse pollutants, leachate is low in biodegradation; therefore, a proper usage of physicochemical treatments is required. In this study, membrane distillation (MD) has been used along with Fenton treatment process for pre-coagulation to achieve an effective removal of contaminants. MD is a technology derived with vapor pressure difference across the hydrophobic membrane which traps the feed-wastewater vapor at the entrance of the hydrophobic side before permeation. MD has several advantages which include reduced operating temperature compared to conventional distillation processes, fewer requirements of membrane cleaning, and lower operating hydraulic pressure than other conventional pressure-driven membrane processes such as reverse osmosis (RO). This technology has a common drawback along with other membrane-required technologies which is dealing with foulants. For a reduction in membrane fouling, Fenton oxidation is coupled in the leachate treatment process. Fenton is reserved to be the most effective for leachate treatment and is widely used due to its simple operation and low costs.

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12

King, Stanley Wayne. "Mass Transfer Analysis of Polyether Sulfone and Polyamide Membranes Modified by Ion Beam Irradiation". University of Toledo / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1083875419.

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13

Chen, Jeffrey Bou-Wei. "Membrane bioreactors for anaerobic treatment of wastewaters". Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/32045.

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Abstract (sommario):

Anaerobic treatment of municipal wastewaters or other wastewaters of weaker strength has conventionally been difficult, especially in regions of cooler climate. Issues with solids retention and sufficient biomass concentration and activities required for treatment are usually of primary concern in these situations. However, the recent incorporation of membranes in the anaerobic treatment of municipal wastewater has made this technology feasible through the absolute retention of biomass within the reactor. Among the many advantages this technology has over its aerobic membrane bioreactor (MBR) counterpart, the most attractive may be the absence of an energy requirement for aeration. Although the anaerobic membrane bioreactor (AnMBR) is a promising technology, limited understanding of the interactions between the reactor biomass and the filtration membranes in the AnMBR has generally confined it to the lab scale level. To this end, the subject of examination for this study is the feasibility of AnMBR treatment of municipal wastewaters, with a strong focus towards membrane operation at moderate operating temperatures. Two experiments were conducted during this study. The first was the long-term operation of two commercially available membranes (hollow fibre and flat sheet) operated in parallel within the reactor. The achievable operational OLR range for the AnMBR was about 1.25 kg COD/m³-d. COD removal efficiency for the AnMBR system during biomass acclimatization was 84% with the addition of supplemental acetate in the feed. This decreased to 43% after the removal of supplemental acetate at a reactor temperature of 25 °C. Biogas production of the system decreased by 20% subsequent to a temperature decrease of 5 °C, due likely to decreased methanogenic activities. The second experiment was to assess the mechanism(s) of membrane flux decline and to compare them with mechanisms identified for the same membranes applied in an aerobic MBR system. The major difference between filtration of the aerobic and anaerobic mixed liquor was the membrane surface cake layer fouling. The observed anaerobic mixed liquor resistance was nearly 100 times greater than the aerobic contribution. It was observed that the mechanism of flux decline of the organic membrane in an anaerobic environment was due to surface cake layer fouling.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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14

Brookes, Adam. "Immersed membrane bioreactors for produced water treatment". Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/4508.

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The performance of a submerged membrane bioreactor for the duty of gas field produced water treatment was appraised. The system was operated under steady state conditions at a range of mixed liquor suspended solids (MLSS) concentrations and treatment and membrane performance examined. Organics removal (COD and TOC) display removal rates between 90 and 97%. Removal of specific target compounds Benzene, Toulene, Ethylbenzene and Xylene were removed to above 99% in liquid phase with loss to atmosphere between 0.3 and 1%. Comparison of fouling rates at a number of imposed fluxes has been made between long term filtration trials and short term tests using the flux step method. Produced water fed biomass displays a greater fouling propensity than municipal wastewater fed biomass from previous studies. Results indicate an exponential relationship between fouling rate and flux for both long and short term trials, although the value was an order of magnitude lower during long term tests. Moreover, operation during long term trials is characterised by a period of pseudo stable operation followed by a catastrophic rise in TMP at a given critical filtration time (tfi, ) during trials at 6 g. L"1. This time of stable operation, tfit, is characterised by a linear relationship between fouling rate and flux. Results have been compared with the literature. Data for membrane fouling prior to the end of t fit yielded a poor fit with a recently proposed model. Trends recorded at t> trlt revealed the fouling rate to follow no definable trend with flux. The system showed resilience to free oil shocking up to an oil concentration of 200ppmv. Following an increase in oil concentration to 500 ppmv, rapid and exponential fouling ensued.

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15

Fawehinmi, Folasade. "Anaerobic membrane bioreactors for municipal wastewater treatment". Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/8042.

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Abstract (sommario):

Anaerobic treatment has historically been considered unsuitable for the treatment of domestic wastewaters. The work presented in this thesis focuses on the incorporation of membranes into the anaerobic bioreactor to uncouple solid retention time and hydraulic retention time. This in turn prevents biomass washout and allows sufficient acclimatisation periods for anaerobes. However, the exposure of membranes to anaerobic biomass comes with its own inherent problems namely fouling. Fouling was found to take place in two stages; a rapid phase characterised by solid and bacterial cell deposition and a slow phase characterised by the travel of colloidal matter to the membrane surface. Gas sparging was also found to attenuate fouling to a considerable extent despite the fact that biomass characteristics were critical factors in the fouling of the system. In addition, side stream membranes showed differing characteristics to submerged membranes. A comparison of anaerobic membrane bioreactors to conventional anaerobic systems and aerobic membrane bioreactors highlighted the advantage of this system over other comparable technologies. The anaerobic membrane bioreactor is less energy intensive than the aerobic membrane bioreactor, fouls differently to this system and achieves much better performance than would be seen if conventional anaerobic systems were used in the treatment of domestic or municipal wastewaters.

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16

Chtourou, Mariem. "Pharmaceutical and personal care products removal by advanced treatment technologies". Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/664966.

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This thesis evaluates different technologies for treating wastewater with high concentrations of PPCPs. Firstly, a state-of-art revision of advanced treatment technology for removing Triclosan (TCS) from waste water was carried out in an attempt to evaluate the most favourable technologies and discern any major limiting factors. The technological categories evaluated were: (i) adsorption, (ii) advanced oxidation processes, and (iii) membrane technology. The results found in the second chapter are based on treating three PPCP compounds in a cyclic anoxic/aerobic membrane bioreactor. In fact, the target compounds selected for this study were specifically carbamazepine, caffeine and triclosan. The ultrafiltration membrane bioreactor process was an efficient and appropriate technology for chemical oxygen demand removal, as it achieved a removal average of 97%, removal rate for caffeine reaching up to 93.7 ± 9.7 and 89.7 ± 8.3 % for triclosan. In the case of carbamazepine, removal was lower (36.2 ± 6.8%) due to its recalcitrance. Low ammonia removal efficiencies were observed in both experimental systems suggesting that nitrification was inhibited by the presence of triclosan. The deterioration of sludge characteristics induced a fouling increment which forced several chemical cleanings to be carried out. The last section is focused on cork and evaluates its potential as a sorbent material. The cork was firstly characterized to discern its structure. Then a fixed-bed column was chosen as the most suitable technology with which to evaluate the cork adsorption. Four pharmaceuticals (diclofenac, ketoprofen, naproxen and carbamazepine) and two cosmetic compounds (triclosan and methylparaben) were treated in wastewater effluent by using a fixed-bed column. Furthermore, a novel, simple, selective and low-cost method for the pre-concentration sample before chromatography was performed in real wastewater effluent. This methodology is based on a silicone rod micro extraction combined with HPLC-DAD to simultaneous determine the concentration levels of six compounds. The adsorption capacities of cork followed this order: TCS >CBZ and MPB> KET and NAP > DCF. This behaviour could be explained by the fact that the removal of PPCPs by cork is based on hydrophobicity and the charge of the PPCP molecules. Generally, the cork showed a much higher capacity for TCS sorption, minimizing the concentrations of triclosan and avoiding the inhibition effect into biological systems, as well as minimizing fouling in MBRs
Aquesta tesi ha avualuat diferents tractament per l'eliminació d'influent amb alta concentració de fàrmacs i productes cosmètics. Primerament, una estat de l’art sobre els diferents tractaments per eliminar triclosan ha permès establir quines tipologies de tractament podrien ser els més rendibles tant a nivell operacional com de costos. Els tractaments avaluats han estat a) adsorció, b) processos d’oxidació avançada, i c) tractament per filtració amb membrana. La tecnologia de membrana va ser una de les tecnologies escollides per analitzar la capacitat per eliminar els productes farmacèutics i cosmètics, així com per poder establir les causes de l’embrutiment de les membranes. Els compostos escollit en aquest estudi van ser el triclosan, la carbamazepina i la cafeïna. Els rendiments d’eliminació van ser elevats pel triclosan i al cafeïna (>90%), mentre que la carbamazepina va ser molt inferior degut a seu poder recalcitrant (<40%). En l’experimentació també es va detectar una inhibició del procés de nitrificació, degut a la presència de triclosan. Aquesta inhibició és va confirmar en un estudi complementari on es va quantificar la pèrdua de la capacitat nitrificant en un 60%. El darrer capítol es centra en l’avaluació de l’adsorció com a tecnologia de tractament. En aquest cas s’ha utilitzat el suro com a material adsorbent i s’han presentat resultats de caracterització del material i resultats de capacitat d’adsorció. Per dur a terme l’experimentació es va triar la tecnologia de llit fix per tractar quatre composts farmacèutics (diclofenac, fetoprofen, naproxen i carbamazepina) i dos productes cosmètics (triclosan i metilparaben). La metodologia d’anàlisi va ser la micro-extracció en tub de silicona amb HPLC-DAD. Els resultats obtinguts van demostrar que el triclosan era el compost amb major capacitat de ser eliminat i el diclofenac el que presentava menors rendiments. TCS> CBZ i MPB> KET i NAP> DCF

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17

Pacholik, Lucy C. "USE OF FUNCTIONALIZED BIMETALLIC MEMBRANES FOR TREATMENT OF CONTAMINATED GROUNDWATER AT A HAZARDOUS WASTE SITE IN KENTUCKY". UKnowledge, 2019. https://uknowledge.uky.edu/ce_etds/83.

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Providing access to clean drinking water will continue to be a challenge for civil engineers for generations to come. Since many communities around the world rely on groundwater as a source of drinking water, remediation technologies must be implemented at sites where groundwater contamination exists due to years of mismanagement of hazardous waste. Using nanosized zero-valent metals such as iron and zinc embedded within and on the surface of functionalized (PAA) membrane filters has shown to be an effective dechlorination technique for contaminated groundwater. Introducing a noble metal such as Pd or Ni increases reaction rates by acting a catalyst for the dechlorination reaction. This study focuses on the treatment of contaminated groundwater at a hazardous waste site in Louisville, Kentucky. Once a chlorinated organic chemical manufacturing plant, the site now operates a treatment system for the contaminated groundwater to prevent migration into the nearby Ohio River. A portable membrane treatment system, built at the University of Kentucky, incorporates this functionalized bimetallic membrane technology for treatment of the groundwater found at the former manufacturing plant. Three bench scale tests were performed with membrane treatment system using DI water spiked with the chemical trichloroethylene (TCE). Results showed that using the functionalized Fe/Pd membranes significant decreased TCE concentrations over time. While further tests should be conducted to verify the results of the preliminary bench-scale tests, the membrane treatment system shows potential for use at the hazardous waste site in Kentucky.

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18

Handelsman, Timothy David. "Membranes for Biorefineries". Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14569.

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This thesis tested the hypothesis that whilst membranes may enable biorefineries to meet discharge specifications, such ‘end-of-pipe’ treatment options are sub-optimal. Greater savings can potentially be made by internal and/or upfront use of membranes. Biorefineries are used to make a wide range of products from substrates such as molasses, corn syrup and cellulosic materials, producing biofuels, pharmaceutical products and mass production of various microorganisms. These are generally produced at low concentrations, resulting in large amounts of wastewater. These wastewaters also contain high concentrations of recalcitrant organic compounds, which have high COD and dark colour. Membrane filtration has in the past typically been used as an ‘end-of-pipe’ treatment option, but can be employed to greater effect further upstream in the baker’s yeast production process. Utilising membrane technology to facilitate the recycling of water and salt from molasses wastewater proved to be successful and could also be used to recover water and other components from lignocellulosic wastewater. Melanoidins are recalcitrant organic macromolecules, which are mainly responsible for the dark brown colour in molasses. The presence of these coloured compounds in the fermentation produces a brown coloured yeast, requiring multiple washing stages to meet the market requirements of the yeast product, the majority of which is sold for the large scale production of sliced white bread. Membranes can be used to remove the bulk of this colour with minimal effect on the yeast’s yield and activity. This thesis has successfully demonstrated the potential of using membrane technologies internally and/or upfront in biorefinery processes, rather than in their customary role as ‘end-of-pipe’ treatment options for both the molasses fermentation industry and the cellulosic ethanol industry, suggesting that membrane technologies have the versatility to be applied across a range of biorefinery processes.

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19

Fonseca, Anabela Duarte. "Denitrification in Membrane Bioreactors". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35212.

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Three membrane bioreactors, a low flux filter (LFF), a diafilter (DF), and an ion-exchange (IE) membrane bioreactor were used to treat water polluted with 50 ppm-N nitrate. The three systems were compared in terms of removal efficiency of nitrate, operational complexity, and overall quality of the treated water. In the low flux filter (LFF) membrane bioreactor an hemo-dialysis hollow fiber module was used and operated continuously for 29 days with a constant flux of permeate. The performance of the system was constant during the span of the experiment, which demonstrated that when the module was operated under constant low flux of permeate, the membrane filtration process was not affected by fouling. The removal rate of the LFF was 100% since the treated effluent did not contain nitrate or nitrite. The volumetric denitrification rate was 240 g-N day-1 m-3, which is within the range of denitrification rates obtained in tubular membrane modules. The treated effluent contained acetate, the carbon source of the biological process, and other inorganic nutrients, which showed that operating this ultrafiltration module at controlled flux did not improve the retention of these substances in the bioreactor. The same hemo-dialysis hollow fiber module employed in the LFF system was used in the diafilter (DF) membrane bioreactor. In the DF system, however, the membrane module was used as a contactor that separated the treated water and the bioreactor system, which allowed the transfer of solutes through the membrane porous structure and supported the growth of a biofilm on the membrane surface. The nitrate removal rate of the DF system increased from 76% to 91% during the 17 days assay. Unfortunately, this improvement could be attributed to microbial contamination of the water circuit because significant concentrations of the carbon source, acetate, nutrients, and nitrate were found in the treated effluent. The volumetric denitrification rate of the system was 200 g-N day-1 m-3, and the surface denitrification rate was lower than values previously reported for contactor membrane bioreactors. The results hereby presented do not evidence any advantage of operating the Filtral 20 ® membrane module as a contactor instead of as a filter such as in the LFF system. On the other hand, the third system herein presented, the IE membrane bioreactor, demonstrated several advantages of a contactor configuration but with a non-porous ion exchange membrane module in place of the Filtral 20 ®. As in a contactor system, the anion membrane provided a surface for biofilm growth, facilitated the transport of nitrate, and prevented mixing of treated water and bioreactor medium. Compared to the two previous systems, the most remarkable result of the IE was the reduction of secondary pollution in the treated water. The concentrations of phosphate and ethanol were zero and less than 1% of the concentration in the bioreactor, respectively. In addition, the IE system was less complex than the two other systems because the ion exchange membrane is non-porous. Therefore, unlike with porous contactors, it was not necessary to control the flux of treated water that could be lost through the bioreactor. The average surface denitrification rate of the IE system was 7.0 g-N day-1 m-2, which is higher than what had been reported for other contactor denitrification systems. However, because of the low surface to volume ratio of the membrane module that was used, the volumetric denitrification rate of the IE system was low, equivalent to 65 g-N day-1 m-3.
Master of Science

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20

Pavasant, Prasert. "Modelling of the extractive membrane bioreactor process". Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266478.

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21

Escalona, Hernández Ivonne Graciela. "Membrane-assisted advanced oxidation processes for wastewater treatment". Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/284445.

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Abstract (sommario):

El bisfenol A (BPA) i la tartrazina (TAR) pertanyen al grup de compostos que són potencialment nocius per a la recuperació d'aigües residuals. El BPA és un disruptor del sistema hormonal o disruptor endocrí, mentre que la TAR és un colorant azoic. Una diversitat d'indústries, especialment la indústria paperera i tèxtil, produeixen un gran volum d'aigües residuals que estan contaminades amb BPA i colorants. Per tant, els efluents que contenen tant BPA com colorants han de ser gestionats de manera eficient amb la finalitat d'evitar problemes ambientals vinculats a ells. Durant l'última dècada, s’han assajat diversos mètodes per a l'eliminació de BPA i TAR d'aigües residuals, resultant ser eficaços i potencialment aplicables a gran escala. No obstant això, la majoria d'ells encara enfronten problemes de costos, la qual cosa exigeix el seu desenvolupament. La nanofiltració (NF) ofereix una solució adequada per a l'eliminació de BPA i colorants de les solucions aquoses, degut a la seva capacitat per retenir substàncies orgàniques dissoltes. És per això que en aquest treball de tesi, es va utilitzar la NF en flux tangencial mitjançant membranes polimèriques per eliminar BPA i TAR de solucions aquoses. Addicionalment, la degradació de BPA i TAR durant els tractaments per Fenton, ozonación i enzimàtic sota diferents condicions d'operació, en combinació amb la seva posterior NF van ser assajats. Resultats indiquen que tant el BPA com la TAR poden ser eficientment degradats per aquests processos. L'ús d'un sistema integrat membrana-reactor va mostrar el potencial i les limitacions de l'ús dels processos d'oxidació avançada en conjunt amb membranes de NF per a la remoció del BPA i de la TAR. En general elevades eficiències de remoció van ser aconseguides amb les diferents membranes de NF utilitzades.
Bisfenol A (BPA) y tartrazina (TAR) pertenecen al grupo de compuestos que son potencialmente dañinos para la recuperación de aguas residuales. BPA es un perturbador del sistema hormonal o disruptor endocrino, mientras que la TAR es un colorante azo. Variedad de industrias, especialmente la industria papelera y textil producen un gran volumen de aguas residuales que están contaminadas con BPA y colorantes. Por lo tanto, los efluentes que contiene tanto BPA como colorantes, deben ser gestionados de manera eficiente con la finalidad de evitar problemas ambientales vinculados a ellos. Durante la última década, varios métodos para la eliminación de BPA y TAR de aguas residuales han sido probados, resultando ser eficaces y potencialmente aplicables a gran escala. Sin embargo, la mayoría de ellos todavía enfrentan problemas de costes, lo cual exige su desarrollo. La nanofiltración (NF) ofrece una solución adecuada para la eliminación de BPA y colorantes de las soluciones acuosas debido a su capacidad para remover sustancias orgánicas disueltas. Es por ello que en esta tesis, la NF en flujo cruzado usando membranas poliméricas fue utilizada para remover BPA y TAR de soluciones acuosas. Adicionalmente, la degradación de BPA y TAR durante los tratamientos por Fenton, ozonación y enzimático bajo diferentes condiciones de operación, en combinación con su posterior NF fueron ensayados. Resultados indican que tanto el BPA como la TAR pueden ser eficientemente degradados por estos procesos. El uso de un sistema integrado membrana-reactor mostró el potencial y las limitaciones del uso de los procesos de oxidación avanzada en conjunto con membranas de NF para la remoción del BPA y de la TAR. En general elevadas eficiencias de remoción fueron alcanzadas con las diferentes membranas de NF utilizadas.
Bisphenol A (BPA) and tartrazine (TAR) belong to the compounds which are potentially harmful during wastewater reclamation. BPA is a typical Endocrine Disrupting Chemical and TAR is an azo dye. Variety of industry, especially paper and textile industries produces a large volume of wastewater that is polluted with BPA and dyes. Therefore, BPA and dyes-charged effluents need to be efficiently managed in order to avoid environmental problems linked to them. During the last decade, several methods for BPA and TAR removal of wastewater have been found effective and potentially applicable for scaling up. However, most of them still face cost problems, thus demanding further development. It is generally accepted that nanofiltration (NF) offers an adequate solution for the removal of BPA and dyes from the aqueous solutions owing to its capacity to remove dissolved organics. In the present thesis, crossflow NF using thin film composite polymeric membranes were applied to reject BPA and TAR from aqueous solutions. Additionally, the degradation of BPA and TAR during Fenton’s, ozonation and enzymatic processes under different operational conditions, in combination with subsequent NF of low concentration remnant BPA and TAR and compounds derived from oxidation was investigated. Results indicate that BPA and TAR could be degraded efficiently in aqueous phase by Fenton, ozonation and enzymatic processes. The use of a membrane-reactor integrated system for BPA and TAR degradation demonstrated the potential and limitations of using advance oxidation processes, operated in a recycling mode coupled to a NF membrane. In general, high BPA and TAR removal efficiencies for several NF membranes were achieved.

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22

Hu, Alan Yung-Chih. "Anaerobic in-tank membrane bioreactor for wastewater treatment". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414422.

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23

Alvarez-Vazquez, H. "Membrane bioreactors for sewage and stabilised leachate treatment". Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/11104.

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Abstract (sommario):

The project aimed to extend the limited knowledge ofMBR (Membrane Bioreactor) operation for the treatment of stabilised (old) landfillleachate using an air-lift tubular membrane configuration and comparing the results with those obtained for sewage treatment under largely identical conditions. SRT (solids retention time) was used as the principal fixed variable in the two trials so as to allow comparison of process performance for the two different feedwaters. Supplementary tests were also conducted on: 1. bench-scale porous pots, used to identify the optimum HRT (hydraulic retention time) value for leachate treatment, and 2. intermittent aeration, used to minimise aeration demand. At bench scale removals of69 ± 1% and 99.9 ± 0.1% chemical oxygen demand (COD) and ammonia (NH/) respectively were achieved at an HR T of 5 d and temperatures ~ 21°C. For this trial the mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSSnvn.SS) ratio was 0.7 ± 0.03 and the volumetric loading rate (VLR) 0.4±0.02 kgCOD m- 3 dol and 0.15 ± 0.003 kgNlI/ m-3 dol; the COD and NH/ food to microorganism ratio (FIM) ratio values were respectively 0.1 ± 0.01 and 0.04 ± 0.004 dol; specific oxygen utilisation rate (SOUR) was 16 ± 7 mg02.gVSS- 1 .h- 1 and nitrifiers:heterotrophs ratio was around 80:20. This compared with similar nitrifiers proportions (i.e. 70 to 80%) reported in the literature. During pilot trials COD removals at the stabilised period were consistently larger for sewage (69 - 83%) than leachates at the pseudo stability phase (28 - 56%), the latter being somewhat lower than values reported in the literature for full-scale plants. However, for both feedwaters maximum was obtained at VLRs between 0.99 and 1.2 kgCOD.m- 3 .d- 1 • NRt + removals were readily achieved with values ~ 88.6%. Biomass characteristics, namely particle size distribution (PSD), extracellular polymeric substances (EPS) concentrations and dynamic viscosity (11) were found to be similar for both sewage and leachate sludges, while soluble microbial products (SMP), MLVSS!.MLSS, F/M, SOUR, and heterotrophslnitrifiers proportions differed. most likely i due to impact of the feedwater character. Microbial dynamics and speciation were highly dependent on feed water quality showing that highly variable feeds such as leachate and sewage would develop inconsistent bacterial communities but analogous to each other. Constant feeds, on the other hand, would develop highly consistent bacterial community profiles. Nevertheless species richness or abundance of neither group (i.e. inconsistent and consistent communities) was significantly correlated to microbial foulants production such as SMP andlor EPS. Even further it was found that either microbial community would have no effect on COD or TOC (total organic carbon) levels of the treated feeds. Critical flux (Je) tests revealed fouling of leachate biomass to be more severe than that imposed by sewage biomass. and that fouling by the leachate biomass is predominantly attributable to the feedwater itself. No correlation between fouling and conventional biomass foulants (i.e. SMP and EPS proteins and carbohydrates) was evident, whilst a stronger correlation of fouling was shown with TOC of the SMP fraction. The ceramic membrane material tested was, as expected, more resistant to fouling than the polymeric membranes used. The highest le values on continuous air-sparging for sewage and leachate were 36 and 24 L.m"2.h"1 respectively. for polymeric membranes, and about 30 L.m"z.h"l during intermittent air-lift conditions for sewage, while absent for leachate. For ceramic membranes no le values were observed at continuous air-sparging. whilst no fouling was evident for either polymeric or ceramic materials challenged with leachate operating with intermittent aeration (0.5 -1 Hz) up to a flux (1) ofl3 and 44 L.m"l.h"l. Cylindrical geometry lumens were found to be more effective during air-lift operations than square lumens.

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24

Alvarez-Vazquez, Héctor. "Membrane bioreactors for sewage and stabilised leachate treatment". Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/11104.

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Abstract (sommario):

The project aimed to extend the limited knowledge ofMBR (Membrane Bioreactor) operation for the treatment of stabilised (old) landfillleachate using an air-lift tubular membrane configuration and comparing the results with those obtained for sewage treatment under largely identical conditions. SRT (solids retention time) was used as the principal fixed variable in the two trials so as to allow comparison of process performance for the two different feedwaters. Supplementary tests were also conducted on: 1. bench-scale porous pots, used to identify the optimum HRT (hydraulic retention time) value for leachate treatment, and 2. intermittent aeration, used to minimise aeration demand. At bench scale removals of69 ± 1% and 99.9 ± 0.1% chemical oxygen demand (COD) and ammonia (NH/) respectively were achieved at an HR T of 5 d and temperatures ~ 21°C. For this trial the mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSSnvn.SS) ratio was 0.7 ± 0.03 and the volumetric loading rate (VLR) 0.4±0.02 kgCOD m- 3 dol and 0.15 ± 0.003 kgNlI/ m-3 dol; the COD and NH/ food to microorganism ratio (FIM) ratio values were respectively 0.1 ± 0.01 and 0.04 ± 0.004 dol; specific oxygen utilisation rate (SOUR) was 16 ± 7 mg02.gVSS- 1 .h- 1 and nitrifiers:heterotrophs ratio was around 80:20. This compared with similar nitrifiers proportions (i.e. 70 to 80%) reported in the literature. During pilot trials COD removals at the stabilised period were consistently larger for sewage (69 - 83%) than leachates at the pseudo stability phase (28 - 56%), the latter being somewhat lower than values reported in the literature for full-scale plants. However, for both feedwaters maximum was obtained at VLRs between 0.99 and 1.2 kgCOD.m- 3 .d- 1 • NRt + removals were readily achieved with values ~ 88.6%. Biomass characteristics, namely particle size distribution (PSD), extracellular polymeric substances (EPS) concentrations and dynamic viscosity (11) were found to be similar for both sewage and leachate sludges, while soluble microbial products (SMP), MLVSS!.MLSS, F/M, SOUR, and heterotrophslnitrifiers proportions differed. most likely i due to impact of the feedwater character. Microbial dynamics and speciation were highly dependent on feed water quality showing that highly variable feeds such as leachate and sewage would develop inconsistent bacterial communities but analogous to each other. Constant feeds, on the other hand, would develop highly consistent bacterial community profiles. Nevertheless species richness or abundance of neither group (i.e. inconsistent and consistent communities) was significantly correlated to microbial foulants production such as SMP andlor EPS. Even further it was found that either microbial community would have no effect on COD or TOC (total organic carbon) levels of the treated feeds. Critical flux (Je) tests revealed fouling of leachate biomass to be more severe than that imposed by sewage biomass. and that fouling by the leachate biomass is predominantly attributable to the feedwater itself. No correlation between fouling and conventional biomass foulants (i.e. SMP and EPS proteins and carbohydrates) was evident, whilst a stronger correlation of fouling was shown with TOC of the SMP fraction. The ceramic membrane material tested was, as expected, more resistant to fouling than the polymeric membranes used. The highest le values on continuous air-sparging for sewage and leachate were 36 and 24 L.m"2.h"1 respectively. for polymeric membranes, and about 30 L.m"z.h"l during intermittent air-lift conditions for sewage, while absent for leachate. For ceramic membranes no le values were observed at continuous air-sparging. whilst no fouling was evident for either polymeric or ceramic materials challenged with leachate operating with intermittent aeration (0.5 -1 Hz) up to a flux (1) ofl3 and 44 L.m"l.h"l. Cylindrical geometry lumens were found to be more effective during air-lift operations than square lumens.

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25

RAO, PRASANNA. "TREATMENT OF ACID MINE DRAINAGE USING MEMBRANE BIOREACTOR". University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1006887417.

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26

Phelane, Lisebo. "Metal nanoparticle modified polysulfone membrane for water treatment". Thesis, University of the Western Cape, 2013. http://hdl.handle.net/11394/4480.

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Abstract (sommario):

>Magister Scientiae - MSc
Membrane separation processes have been widely applied in the treatment of wastewater with polysulfone (PSF) polymer membrane being the most frequently used in ultrafiltration of wastewater due to its chemical and structural stability and mechanical robustness. The disadvantage to these membranes is their hydrophobicity which leads to membrane fouling caused by organic pollutants in water. Many studies have been conducted to increase the hydrophilic properties of the polysulfone membrane surface. Most recently metal oxide nanoparticles have been introduced to the polymer matrix in order to reduce membrane fouling and increase its hydrophilicity with measurable success. Natural organic matters are the one of the major fouling agents during ultrafiltration, reverse osmosis and microfiltration. Two organic acids (Tannic Acid and Alginic Acid) were selected to test the fouling behaviour of nanometallic synthesised polysulfone membranes. For this study, polysulfone casting suspension was prepared by dissolving polysulfone beads in N,N-dimethly acetamide. Three metallic nanoparticles of Silver, Cobalt and Nickel were selected to improve the hydrophilicity of the polysulfone membrane. The metal nanoparticles were prepared using the chemical reduction method. Cobalt nanoparticles were synthesized by dissolving the cobalt chloride salt in deionized water and reduced with sodium borohydride at room temperature. The nickel chloride salt was dissolved in ethanol and reduced with sodium borohydride under magnetic stirrer. Silver nanoparticles were prepared by dissolving the silver nitrate in deionised water and heated to boil, the sodium citrate was added to reduced the silver nitrate. These nanoparticles were then integrated into the polysulfone polymer matrix to form the metal nanoparticle polysulfone nanocomposites. This study focused on four prepared polysulfone nanocomposite membrane; 1 unmodified polysulfone (PSF), 2 polysulfone modified with cobalt nanoparticles (PSF/Co), 3 polysulfone modified with nickel nanoparticles (PSF/Ni) and 4 polysulfone modified with silver nanoparticles (PSF/Ag).

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27

Banks, Stacie. "The treatment of landfill leachate using an MFUF membrane system: Focusing on membrane fouling". Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26572.

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Membrane systems are being used increasingly throughout the western world to treat landfill leachate as environmental regulations tighten. This work examined leachate filtration using a bench-scale MF/UF membrane system, focussing on surface fouling and constituent reductions at the Trail Road Landfill in Ottawa, Ontario. The study found that ultrafiltration membranes with a molecular weight cut-off of 10 KDa and below gave the best overall leachate treatment. A 1 KDa ultrafiltration membrane gave the highest percent removals overall of all the membranes tested, but had one of the lowest steady state fluxes ranging from 2 to 5 L/m2h. Carbonates such as calcite and dolomite were determined to be one of the main foulants/scalants. Iron sulphides or iron oxides tended to form a general coating over the membrane surface and may have been the base for a surface coating of mixed-element origins observed in spring 2003. The fouling type was generally thought to be cake filtration based on flux results and basic fouling determination equations. (Abstract shortened by UMI.)

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28

Keen, Michael. "Evaluation of the impact of membrane change at a membrane softening water treatment plant". [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002961.

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29

Semião, Andrea J. C. "Removal of adsorbing estrogenic micropollutants by nanofiltration membranes in cross-flow : experiments and model development". Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5742.

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Abstract (sommario):

Nanofiltration (NF) can be used in water and wastewater treatment as well as water recycling applications, removing micropollutants such as hormones. Due to their potential health risk it is vital to understand their removal mechanisms by NF membranes aiming at improving and developing more effective and efficient treatment processes. Although NF should be effective and efficient in removing small molecular sized compounds such as hormones, the occurrence of adsorption onto polymeric membranes results in performances difficult to predict and with reduced effectiveness and efficiency. This study aims firstly at defining, understanding and quantifying the relevant filtration operation parameters and, secondly, in identifying the physical mechanisms of momentum and mass transfer controlling the adsorption and transport of hormones onto polymeric NF membranes in cross-flow mode. The hormones estrone (E1) and 17-b-estradiol (E2) were chosen as they have very high endocrine disrupting potency. The NF membranes used and tested were the NF 270, NF 90, BW30, TFC-SR2 and TFC-SR3 since they have a wide span of pore sizes. The first step is to experimentally acquire the knowledge of how fluid flow hydrodynamics and mass transfer close to the membrane affect hormone adsorption. The focus will be particularly on the effect of operating pressure, circulating Reynolds numbers (based on channel height, Reh) and hormone feed concentration. These hydrodynamic parameters play an important role in concentration polarisation development at the membrane surface. A Reh increase from 400 to 1400 for the NF 270 membrane caused the total mass adsorbed of E1 and E2 to decrease from 1.5 to 1.3 ng.cm-2 and 0.7 to 0.5 ng.cm-2, respectively. In contrast, a pressure increase from 5 to 15 bar yielded an increase in the adsorbed mass of E1 and E2 from 1.0 to 1.8 ng.cm-2 and 0.5 to 0.7 ng.cm-2, respectively. Moreover, increasing hormone feed concentration caused an increase in the mass adsorbed for both hormones. These observations led to the conclusion that adsorption is governed by the initial concentration at the membrane surface which, in turn, depends on the hormone feed concentration, operating Reh and pressure. Membrane retention, however, depends on the initial polarisation modulus, defined as the ratio between the initial concentration at the membrane surface and the initial feed concentration. The same trends were obtained for the TFC-SR2 membrane. However, this membrane has a much lower permeability compared to the NF 270 one (7.2 vs 17 L.h-1.m-2.bar-1, respectively) and concentration polarisation is less severe. The experimental variations in mass adsorbed and retention as a function of the operating filtration parameters (Reh and pressure) were therefore lower. Based on these experimental results, a sorption model was developed. This model predicts well both feed and permeate transient concentrations for both hormones and membranes (NF 270 and TFC-SR2) in the common range of operating pressures and Reh of spiral-wound membrane modules. The model was further applied for E2 in the presence of background electrolyte, yielding good predictions. These findings are an important advancement in determining which membrane would be more suitable to effectively remove hormones with a substantial reduction of experimental work. The above-mentioned developed model does not give insight into the phenomena occurring inside the membrane since it focuses on the feed conditions. However, membrane characteristics, such as material and pore radius were found to have an impact in adsorption and retention of hormones. It was found experimentally that polyamide, from which the active layer of the NF membranes is made, adsorbs three times more mass of hormone than any other polymers constituting the membranes. Since this active layer is the membrane selective barrier of the membrane that is in contact with the largest hormone concentration (due to concentration polarization in the feed solution) it is concluded that the active layer adsorbs most of the hormones. Further experimental work carried out in this thesis showed that increasing the pore radius from 0.32 nm to 0.52 nm increased the E2 mass adsorbed from 0.17 ng.cm-2 to 1.1 ng.cm-2 and decreased the retention from 88% to 34%. These results show that the wider the pore, the larger the quantity of hormone that penetrates (i.e. partitions) inside the membrane and, therefore, the more the membrane adsorbs the hormone. For membranes of similar pore radius, the membrane with larger internal surface area was found to adsorb more. All the previous results led to the establishment of a new model for the hormone transport inside the membrane pore taking convection, diffusion and adsorption into account. Since the differential equation describing the transport with adsorption inside the pore has no analytical solution, a numerical model based on the finite-difference approach was applied. With such a model, its validation against experiments and parametric studies it was possible to understand the transport mechanisms of adsorbing hormones through NF membranes. The results show that for low pressures the hormone transport is diffusion dominated. In contrast, for higher pressures (above 11 bar) the transport is convection dominated, showing that a purely diffusion transport model does not describe well the actual transport phenomena of hormones in NF membranes. Furthermore, it was found that two similar molecules can behave very differently in terms of adsorption on the membrane. E1, which adsorbs 20% more than E2 in static mode, being slightly smaller than E2, partitions more inside the membrane pore and adsorbs double under filtration conditions. This study contributes to illuminating the adsorption mechanisms of hormones onto NF membranes by understanding what parameters control adsorption such as hydrodynamics, materials, structure, etc. This not only identifies a potential problem in large scale applications, but it also provides an understanding of the mechanisms involved in the removal of these hormones and a tool that can be used to design future membranes for the improvement of micropollutant removal.

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30

Goldman, Joshua E. "Relationship between biofilm removal and membrane performance using Dunedin reverse osmosis water treatment plant as a case study". [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002162.

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31

Yan, Bing. "Effects of Thermal Treatments on Perfluorosulfonate Ionomer Membranes". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/44195.

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Abstract (sommario):

Perfluorosulfonate ionomer (PFSI) membranes were annealed at elevated temperature for various periods of time in order to investigate the morphological effects of thermal treatments. For NafionÂ® 117, the DSC thermograms of Na+-, Cs+- and tetramethylammonium(TMA+)-form membranes show an endothermic peak develops upon annealing at 200ÂºC, indicating the development of crystallinity in the membrane. For these three samples annealed under same conditions, the heat of fusion (Î H) values of the endothermic event increases with increasing counterion size. Larger tetraalkylammonium ions, tetraethylammonium(TEA+) and tetrapropylammonium(TPA+), result in no significant peak upon annealing at 200ÂºC. DSC thermograms of annealed Na+-form 3M Ionomer show no peak upon annealing and DSC thermograms of annealed TMA+-form 3M Ionomer show a very small peak that develops with annealing time at high equivalent weights. Annealed TMA+-form Dow Ionomer, which has a side chain shorter than both NafionÂ® and 3M Ionomer and a smaller mole% of side chains at the same equivalent weight, shows a relatively high Î H value, which might also be related to its blocky nature. These results show that the isothermal crystallization kinetics of PFSI is affected by the counterion attached to the sulfonate group, the length of side chain, the mole% of side chains and the nature of the membrane. Water uptake analysis has been performed on annealed membranes, and the result shows that water uptake decreases with increasing degree of crystallinity.
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32

Walker, Steven. "Hollow Fiber Ultrafiltration of Ottawa River Water: Impact of Different Pre-treatment Schemes". Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31323.

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To minimize membrane fouling many water treatment plants pre-treat water prior to microfiltration (MF) or ultrafiltration (UF). Coagulation/flocculation/sedimentation is a common form of pre-treatment, but little research has been conducted on floatation as a part of the pre-treatment. The objective of this thesis is to compare pre-treatment with floatation and with sedimentation for Ottawa River water, a typical Northern Canadian water with a high natural organic matter (NOM) content and a large hydrophobic (HPO) NOM fraction. Fouling tests consisted of multiple filtration/backwashing cycles performed by an automated bench-scale UF hollow fiber membrane system. Test were conducted with Ottawa River water (ORW) and ORW subjected to three different types of pre-treatment conducted at closely-located full-scale water treatment plants, including one using floatation. Both Alum pre-treatments resulted in decreases in NOM (63% and 68% TOC) and HPO NOM (56% and 68%TOC) which helped to reduce fouling. However, the remaining NOM and HPO NOM still caused significant hydraulically and chemical irreversible fouling. The water pre-treated with floatation produced the least severe hydraulically irreversible fouling for all experiments while Raw ORW produced the highest. During the early stages of membrane filtration (~10 hours), the TMP sharply increases which may imply that adsorption is dominant. Statistical analysis during the initial stages of filtration showed that the HPO fraction of NOM was linked to hydraulically irreversible fouling, which may be attributed to adsorption. Raw ORW also had the highest hydraulically reversible fouling while all pre-treatments were able to reduce this type of fouling. Statistical analysis suggested that the transphilic (TPI) fraction of NOM and particulate organic carbon (POC) were responsible for hydraulically reversible fouling during subcritical flux experiments, which may be attributed to cake formation on the membrane surface. It was found that for all waters and experiments, hydraulically irreversible fouling was greater than hydraulically reversible fouling. This may be because of the high HPO concentrations in the ORW. Hydraulically reversible fouling and backwash efficiencies were found to fluctuate with time. It is hypothesised that the cake formation adheres to the membrane surface and is not fully removed until enough backwash pressure has developed. Further investigation into alternative cleaning procedures is required as the NaOH cleaning was not very effective for some of the pre-treated waters.

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33

Giacobbo, Alexandre. "Biorreator à membrana aplicado ao tratamento de efluentes". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26538.

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A preocupação com a qualidade das águas está intensificando estudos com tecnologias avançadas para tratamento de efluentes. Uma tecnologia promissora no Brasil é a de biorreatores à membrana (MBR), pois há a possibilidade de trabalhar com altas taxas de aplicação e ainda pode obter um efluente tratado passível de reuso. Assim, o presente trabalho teve por objetivo estudar um MBR com módulo de membranas externo. Para tanto, foram estipulados os parâmetros operacionais em ensaios preliminares, tais como compactação da membrana, permeabilidade hidráulica e permeabilidade ao lodo ativado. Desta forma, efetuou-se a montagem do MBR, o qual foi inicialmente alimentado com um efluente sintético e posteriormente com efluente de curtume coletado pós-tratamento convencional. Operando com efluente sintético, obteve-se redução superior a 95% para DQO e turbidez. Com efluente de curtume pós-tratamento, obteve-se eficiência de 46%, 88%, 16%, 67% e 48% para DQO, DBO5, NTK, P-Total e cromo, respectivamente. Ademais, após 15 dias de operação, o sistema estabilizou com fluxo permeado elevado: 43 L/m².h.
The preoccupation with the quality of water resources is intensifying studies about advanced technologies for wastewater treatment. A promising technology in Brazil is the membrane bioreactors (MBR), due its capacity to operate with high application rates and may also obtains a treated effluent able to reuse. Thus, this work aimed to study a MBR with external membrane module. Firstly, it has been determined operational parameters by preliminary studies, namely: membrane compactation, hydraulic permeability and permeability to activated sludge. After that, the MBR was setting. Then, it was initially fed a synthetic wastewater and, then, with tannery wastewater collected after conventional treatment. Operating with synthetic wastewater, it was obtained a reduction of more than 95% for COD and turbidity. The operation with tannery wastewater post treatment resulted in efficiency of 46%, 88%, 16%, 67% and 48% for COD, BOD5, TKN, Total-P and chromium, respectively. Moreover, after 15 days of operation, the system has stabilized with high permeate flux: 43 L/m².h.

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34

Alkmim, Aline Ribeiro. "Membrane Bioreactor for treating petroleum refinery effluent: treatment performance, membrane fouling mechanism and fouling control". Universidade Federal de Minas Gerais, 2015. http://hdl.handle.net/1843/BUBD-9Y2HVT.

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The work developed discusses the potential use of MBR to treat refinery effluent and operational strategies that may mitigate fouling. At first, MBR performance was evaluated in terms of pollutants removal and fouling investigation in conditions of shock load. The results demonstrated that MBR was able to reduce effectively the pollutants, meeting guideline standards of disposal and reuse for non-potable ends. FTIR results showed that organic matter was removed by biological oxidation and/or retained by adsorption in the biological sludge or retention in the UF membrane. Furthermore, SMP was produced during treatment. In terms of membrane permeability, the results showed that the soluble fraction of mixed liquor contributed significantly to membrane fouling due to the presence of SMP fraction. Secondly, the sludge filterability was studied as an important parameter to evaluate sludge properties and the potentiality of membrane fouling in MBR. Three filterability assessment methods described in the literature were compared regarding their capability to sense sludge quality variation and reproducibility treating petroleum refinery effluents. This study showed that, among the methods evaluated, Time To Filter was the most effective to assess the filterability both in terms of its capability to detect sludge quality variation and reproducibility. The results have also shown that filterability is directly related to membrane fouling potential, and can be used as a tool to monitor and control fouling process in MBR. Significant filterability correlations among colloidal TOC, EPS and floc size were found. The third study assessed the long-term use of cationic polyelectrolyte to improve the sludge filterability, as well as membrane fouling control in bioreactor membrane while treating refinery effluents. Corrective and preventive cationic polyelectrolyte dosages have been added to the MBR in order to evaluate the membrane fouling mitigation in both strategies. The results have confirmed that the use of this product increased sludge filterability, and reduced membrane fouling. During monitoring time stress events occurred due to increase in oil and grease and phenol concentrations in the MBR feed. The preventive use of cationic polyelectrolyte allowed a more effective and stable sludge filterability with lower consumption without decreasing MBR pollutant removal overall performance.
O trabalho desenvolvido aborda o uso do BRM tratando efluente de petróleo e estratégias operacionais que possam minimizar a incrustação. Primeiramente, avaliou-se o desempenho do BRM em termos de remoção de poluentes e investigou-se o comportamento da incrustação em ocorrências de cargas de choque. Os resultados demonstraram que o BRM foi capaz de reduzir efetivamente os poluentes, alcançando padrões de descarte e reuso. Os resultados de IV mostraram que a matéria orgânica é removida por oxidação biológica e/ou retenção por adsorção no lodo biológico ou retenção pela membrana. Além disso, verificou-se que o SMP é produzido durante o tratamento. Em relação à permeabilidade da membrana, verificou-se que a fração solúvel do lodo biológico contribui significativamente para a incrustação da membrana devido a presença de SMP. No segundo estudo a filtrabilidade do lodo foi estudada como um importante parâmetro para a avaliação das propriedades do lodo e o potencial de incrustação da membrana em BRM. Foram comparados três métodos de determinação da filtrabilidade relatados na literatura em termos de capacidade de detecção de variações da qualidade do lodo e da reprodutibilidade, avaliando a aplicação deste parâmetro como ferramenta para o monitoramento e controle de incrustação de BRM. O estudo mostrou que o método Time To Filter foi o mais eficiente para medição da filtrabilidade, tanto em termos de capacidade de detecção de variação da qualidade do lodo, como em reprodutibilidade. Verificou-se também que a filtrabilidade está diretamente relacionada ao potencial de incrustação na membrana. Encontraram-se correlações significativas da filtrabilidade com os parâmetros COT coloidal, EPS e tamanho de floco. No terceiro estudo, avaliou-se a utilização de um polieletrólito catiônico a fim de melhorar a filtrabilidade do lodo e consequentemente controlar a incrustação da membrana. Dosagens corretiva e preventiva do polieletrólito foram realizadas nos BRM a fim de avaliar o melhor controle da incrustação nas duas estratégias. Os resultados confirmaram que o uso do produto aumenta a filtrabilidade do lodo e reduz a incrustação da membrana. Durante o período de monitoramento ocorreram choques de carga com altas concentrações de óleos e graxas e fenol na alimentacão. O uso preventivo do polieletrólito catiônico permitiu uma filtrabilidade mais efetiva e estável sem prejudicar o desempenho do BRM quanto à remoção de poluentes.

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35

Abegglen, Christian Konrad. "Membrane bioreactor technology for decentralized wastewater treatment and reuse /". Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17998.

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36

Bernat, Camí Xavier. "Treatment of biorefractory wastewater through membrane-assisted oxidation processes". Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/8583.

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Abstract (sommario):

La escasez de agua se presenta como uno de los mayores retos para asegurar el desarrollo sostenible. Entre otras actuaciones, se deben investigar e implementar sistemas eficientes de tratamiento de aguas biorecalcitrantes, que necesitan ser condicionadas antes de su depuración biológica. Uno de los posibles pre-tratamientos es el proceso Fenton de oxidación avanzada, que presenta dos principales inconvenientes: la utilización de sales de hierro como catalizador homogéneo, que abandonan continuamente la etapa de oxidación, y el elevado consumo de oxidante, en parte desaprovechado. La presente tesis se centra en el estudio de la mejora del proceso Fenton de aguas fenólicas mediante su acoplamiento con tecnologías de membrana como la nanofiltración, la emulsificación con membranas o los reactores de membrana. El acoplamiento de dichas tecnologías con el proceso Fenton permite el confinamiento del catalizador y el aumento de la eficiencia de oxidación, mejorando así el tratamiento en términos ambientales y económicos.
Water scarcity is one of the major challenges for assuring a sustainable development. Among other measures, research into efficient wastewater treatment systems to deal with biorefractory wastewaters, which need to be amended before their biological degradation, is required. The Fenton process is an advanced oxidation process that can be used as potential pre-treatment for this purpose. However, the pre-treatment presents two main limitations: the use of iron salts as homogeneous catalyst, which are continuously thrown away in the reactor effluent, and the high consumption of oxidant, which is partially wasted. The present thesis aims at studying the improvement of the Fenton process applied on phenolic wastewater through its coupling with membrane technologies such as nanofiltration, membrane emulsification or membrane reactors. The coupling allows confining the catalyst and increasing the oxidation efficiency, thus enhancing the treatment efficiency in environmental and economic terms.

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37

Lambie, Mark Robert. "Local membrane versus systemic consequences of peritoneal dialysis treatment". Thesis, Keele University, 2015. http://eprints.keele.ac.uk/2328/.

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The primary intent of this thesis is to delineate the relative roles of local membrane and systemic consequences of peritoneal dialysis therapy, with particular reference to the role of inflammation and a severe, uncommon complication, encapsulating peritoneal sclerosis (EPS). Data sources comprised observational cohort studies as well as registry data: the Stoke PD study, a single centre study with clinical data, the Global Fluid Study (GFS), a multinational study with clinical data and repeated dialysate and plasma samples, and Scottish Renal Registry (SRR) and AnzData registry data. Through a cross sectional analysis of dialysate and plasma samples from GFS for inflammatory cytokines, we demonstrated that peritoneal and systemic inflammation are mostly separate processes although there is an association for IL-6 along with a steep concentration gradient from dialysate to plasma. Peritoneal inflammation, though IL-6, is the strongest determinant of peritoneal solute transport, and systemic inflammation, though IL-6, is a strong predictor of patient survival although peritoneal may contribute to systemic inflammation. Through a nested case control study of GFS we showed that inflammatory cytokines are upregulated within the peritoneum prior to developing EPS. With a nested case control design from the Stoke PD study, we showed that a decrease in ultrafiltration, likely due to increased fibrosis causing a reduction in osmotic conductance to glucose, also predisposes to EPS. A competing risks analysis of SRR and AnzData showed that patients at a high risk of death, have a low risk of EPS. These findings provide supporting evidence for the theory that the risk of EPS develops through the accumulation of inflammation-driven fibrosis due to dialysate exposure over a long period of time. Dialysate contains high concentrations of glucose and absorption of this drives impairment of systemic glucose metabolism, demonstrated through a cross sectional analysis of GFS.

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38

Murray, Simon Thomas. "Applications of membrane aerated biofilm reactors for wastewater treatment". Thesis, Queen's University Belfast, 2016. https://pure.qub.ac.uk/portal/en/theses/applications-of-membrane-aerated-biofilm-reactors-for-wastewater-treatment(af60a6ed-09b7-4b95-8730-d3de83b3876e).html.

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Despite being the subject of peer reviewed research since the mid-1980s, the conservative nature of the wastewater treatment industry means that the commercial application of membrane aerated biofilm reactors has not realized the potential that the published research demonstrates. The early research demonstrated the ability of membrane aerated biofilm reactors to achieve good levels of pollutant removal from various types of wastewater, but also exposed several weaknesses of the technology (i.e. cost of membranes, control of biofilm thickness) which have prevented the concept of MABfRs being developed in viable wastewater treatment technologies. However, as membrane technology has developed, the cost of suitable membranes has fallen, prompting the research community to revisit the concept. This later batch of research has identified several niche applications where membrane supported biofilms can be used for effective removal of pollutants from water. Using the MABfR for the treatment of secondary effluent as a polishing step is another niche application which has been identified and is examined in this work; leading to the development of a patented treatment technology – the BioSettler.

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39

Facey, Roderick M. "Treatment of pulp mill membrane concentrates by freeze-thaw". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ39525.pdf.

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40

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.

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41

Skouteris, George S. "Low energy membrane bioreactors for decentralised waste water treatment". Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527518.

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42

Janus, Tomasz. "Modelling and simulation of membrane bioreactors for wastewater treatment". Thesis, De Montfort University, 2013. http://hdl.handle.net/2086/9507.

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Abstract (sommario):

The work presented in this thesis leads to the formulation of a dynamic mathematical model of an immersed membrane bioreactor (iMBR) for wastewater treatment. This thesis is organised into three parts, each one describing a different set of tasks associated with model development and simulation. In the first part, the Author qualitatively and quantitatively compares various published activated sludge models, i.e. models of biochemical processes associated with bacterial growth, decay, lysis and substrate utilisation in activated sludge systems. As the thesis is focused on modelling membrane bioreactors (MBRs) which are known to experience membrane fouling as a result of adsorption of biopolymers present in the bulk liquid onto and within the membrane, all activated sludge models considered in this thesis are able to predict, with various levels of accuracy, the concentrations of biopolymeric substances, namely soluble microbial products (SMP) and extracellular polymeric substances (EPS). Some of the published activated sludge models dedicated to modelling SMP and EPS kinetics in MBR systems were unable to predict the SMP and EPS concentrations with adequate levels of accuracy, without compromising the predictions of other sludge and wastewater constituents. In other cases, the model equations and the assumptions made by their authors were questionable. Hence, two new activated sludge models with SMP and EPS as additional components have been formulated, described, and simulated. The first model is based on the Activated Sludge Model No. 1 (ASM1) whereas the second model is based on the Activated Sludge Model No. 3 (ASM3). Both models are calibrated on two sets of data obtained from a laboratory-scale system and a full-scale system and prove to be in very good agreement with the measurements. The second part of this thesis explains the development of two membrane fouling models. These models are set to describe the loss of membrane permeability during filtration of various solutions and suspensions. The main emphasis is placed on filtration of activated sludge mixtures, however the models are designed to be as general as feasibly possible. As fouling is found to be caused by a large number of often very complex processes which occur at different spatial as well as temporal scales, the two fouling models developed here have to consider a number of significant simplifications and assumptions. These simplifications are required to balance the model's accuracy, generality and completeness with its usability in terms of execution times, identifiability of parameters and ease of implementation in general purpose simulators. These requirements are necessary to ascertain that long term simulations as well as optimisation and sensitivity studies performed in this thesis either individually on fouling models or on the complete model of a MBR can be carried out within realistic time-scales. The first fouling model is based on an idea that fouling can be subdivided into just two processes: short-term reversible fouling and long-term irreversible fouling. These two processes are described with two first order ordinary differential equations (ODEs). Whilst the first model characterises the membrane filtration process from an observer's input-output point of view without any rigorous deterministic description of the underlying mechanisms of membrane fouling, the second model provides a more theoretical and in-depth description of membrane fouling by incorporating and combining three classical macroscopic mechanistic fouling equations within a single simulation framework. Both models are calibrated on a number of experimental data and show good levels of accuracy for their designated applications and within the intended ranges of operating conditions. In the third part, the first developed biological model (CES-ASM1) is combined with the behavioural fouling model and the links between these two models are formulated to allow complete simulation of a hollow fibre (HF) immersed membrane bioreactor (iMBR). It is assumed that biological processes affect the membrane through production of mixed liquor suspended solids (MLSS), SMP and EPS which cause pore blockage, cake formation, pore diameter constriction, and affect the specific cake resistance (SCR). The membrane, on the other hand, has a direct effect on the bulk liquid SMP concentration due to its SMP rejection properties. SMP are assumed to be solely responsible for irreversible fouling, MLSS is directly linked to the amount of cake depositing on the membrane surface, whereas EPS content in activated sludge affects the cake's SCR. Other links provided in the integrated MBR model include the effects of air scouring on the rate of particle back-transport from the membrane surface and the effects of MLSS concentration on oxygen mass transfer. Although backwashing is not described in great detail, its effects are represented in the model by resetting the initial condition in the cake deposition equation after each backwash period. The MBR model was implemented in Simulink® using the plant layout adopted in the MBR benchmark model of Maere et al. [160]. The model was then simulated with the inputs and operational parameters defined in [36, 160]. The results were compared against the MBR benchmark model of Maere et al. [160] which, contrary to this work, does not take into account the production of biopolymers, the membrane fouling, nor any interactions between the biological and the membrane parts of an MBR system.

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43

Hopkins, Janet. "Plasma treatment of polysulfone gas separation membranes". Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5231/.

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The chemical and topographical nature of a polymer surface can be changed by non-equilibrium glow discharge treatment. Surface modification of polysulfone and polyethersulfone was examined using a variety of plasma treatments at a fixed power, pressure and treatment time. The modification observed was found to be dependent upon the type of feed gas employed. Tetrafluoromethane plasmas fluorinate polymer surfaces. The influence of polymeric structure on the extent of modification was examined. Phenyl ring containing polymers experienced a greater extent of modification compared to saturated polymers. The extent of modification is dependent upon both the fluorination mechanism and the surface affinity. Plasmas contain a variety of species accompanied by an electromagnetic spectrum. The role of vacuum ultraviolet radiation in a plasma was investigated as a function of feed gas (argon, krypton, xenon and oxygen) on polyethylene and polystyrene, in an oxygen atmosphere. The xenon vacuum ultraviolet treatment gave rise to the greatest oxidation whilst the O(_2) vacuum ultraviolet treatment was found to result in the least oxidation. The activation mechanisms varied with the feed gas chosen for the experiment. Non-equilibrium glow discharge treatment can alter the transport properties of gases permeating through an asymmetric polysulfone membrane. The selectivity and permeability alter as a function of the treatment. The deposition of a methane plasma polymer onto the surface of the membrane resulted in an increase in the gas flux. Similarly CF(_4) plasma treatment also gave rise to an increase in the gas flux. The deposition of a methane plasma polymer followed by a CF(_4) plasma treatment resulted in a decrease in gas flux and a small increase in the oxygen/nitrogen selectivity.

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44

Saleem, Mubbshir. "Application of dynamic membranes in wastewater treatment". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3422308.

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The research highlighted the performance of dynamic membrane (DM) in most challenging conditions where advanced technologies like MBR etc. have been successfully applied. In this regard, treatment of old landfill leachate, production of bio hydrogen and enrichment of Anammox bacteria was mostly focused. The research also presented the strategies to expedite the formation of DM under both aerobic and anaerobic conditions. Pneumatic In situ cleaning mechanism was also proposed and proved to be effective in speedy and effective permeability recovery of excessively fouled DM under anaerobic conditions without chemical cleaning. Similarly, the effect of feed characteristics on development and performance of DM was also highlighted for the first time and the associated role of mesh porosity of underlying support was also discussed.
La ricerca ha evidenziato le prestazioni della membrana dinamica (DM) nelle condizioni più difficili in cui sono state applicate con successo tecnologie avanzate come MBR ecc. A questo proposito, il trattamento del percolato di discarica precedente, la produzione di bio idrogeno e l'arricchimento dei batteri Anammox sono stati principalmente concentrati. La ricerca ha anche presentato le strategie per accelerare la formazione di DM in condizioni sia aerobiche che anaerobiche. È stato anche proposto un meccanismo di pulitura in situ pneumatico che si è dimostrato efficace nel recupero rapido ed efficace della permeabilità del DM eccessivamente sporco in condizioni anaerobiche senza pulizia chimica. Allo stesso modo, l'effetto delle caratteristiche del mangime sullo sviluppo e sulle prestazioni del DM è stato anche evidenziato per la prima volta e anche il ruolo associato della porosità della mesh del supporto sottostante è stato discusso.

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45

Strachan, Laura Fay. "The Extractive Membrane Bioreactor : flux enhancement and biofilm control". Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266892.

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46

Ferrer, Mallén Olga. "Substitution of conventional pre-treatment units by membrane based processes in drinking water treatment". Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/334975.

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This thesis focused on the feasibility of substituting, partially or totally, drinking water treatment plant (DWTP) conventional pre-treatment by membrane based units, in particular by ultrafiltration (UF). For such purpose, bench and pilot scale tests with natural water were conducted, first, to address the technical feasibility and, second, to optimize its performance in order to determine whereas the proposed scheme was competitive from hydraulic and quality perspectives with the current conventional pre-treatment. Moreover, tailored microbes based tests were defined to assess its proper functioning and reliability, and additional advantages related to direct UF besides those purely related to the pre-treatment unit were investigated. The case study selected was Sant Joan Despí DWTP (Barcelona, Spain) due to its particularities: it treats Llobregat River water, which is a highly variable water resource in terms of quality and quantity, and it is a complex multistage system. As a result, this study covered a wide range of conditions and the technology under consideration could be pushed to its limits. Results showed that direct UF of raw river water was a competitive alternative to dioxichlorination, coagulation/flocculation, settling and sand filtration. The pilot plant was able to continuously treat raw river water during 2 years, independently of its quality (e.g. turbidity > 1,000 NTU), delivering water of high and stable quality, both physico-chemically and microbiologically. In terms of pre-treated water quality, most of the physico-chemical parameters monitored presented lower values and variability in the direct UF scheme than in the conventional pre-treatment process. From a microbiological perspective, the direct UF scheme tested ensured an average removal of > 5 log10 units of bacteria and viruses greater than 60 nm. The highest water yields achieved ranged between 94.0%-94.7% in optimal conditions, involving 1 or 2 chemically enhanced backwashes (CEBs) per day, transmembrane pressure (TMP) below 1 bar, filtration fluxes of 40¿70 L/(m2¿h) and low reagents consumption. When a micro-coagulation previous to the UF was applied, the increase of the hydraulic resistance during filtration was decreased and stabilized, especially in winter, the hydraulic cleaning efficiency raised and the CEB frequency diminished. Since fouling indicators (SDI15 and MFI0.45) of the direct UF permeate were lower than those associated to the conventional pre-treatment, the subsequent reverse osmosis (RO) unit would require less chemical cleanings and thus, its lifetime would be extended. In addition to this, besides the economic savings associated to the significant reduction of reagents dosed within the direct UF scheme (chemical disinfectants and coagulants mainly), a minimization of risk of RO membrane degradation was demonstrated. Studies concerning the effects on physico-chemical and transport properties of RO membranes exposed to chemicals used within the conventional pre-treatment scheme but avoided in the direct UF treatment were also undertaken. An advanced characterisation of the exposed membranes enabled understanding the RO membranes performance changes with its composition and structure modification. The implementation of direct UF would imply the pre-treatment being a single membrane filtration step. This has advantages in terms of process complexity, space requirements, as well as avoidance of chemical based disinfectants dosage. Nevertheless, the preservation of its separating properties along time is of utmost importance, especially from a microbiological standpoint. Consequently, microbes based tailored tests aiming at assessing membrane integrity were defined and conducted periodically, to determine the removal capacity reliability of the pre-treatment scheme proposed in this thesis. Results showed that membrane integrity had not been compromised despite the challenging conditions that direct UF posed.
Aquesta tesis s'ha centrat en l'estudi de la substitució, total o parcial, de l'etapa de pre-tractament d'estacions de tractament d'aigua potable (ETAPs) per processos de membrana, en particular per ultrafiltració (UF). Per a tal fi, es van realitzar experiments a nivell laboratori i pilot per, en primer lloc, avaluar la seva viabilitat tècnica, i en segon, optimitzar el seu funcionament per determinar així si l'esquema de tractament proposat era competitiu des d'un punt de vista hidràulic i de qualitat amb el pre-tractament convencional actual. A més, es van definir assajos per assegurar el seu correcte funcionament i fiabilitat, i es van identificar avantatges addicionals a les purament associades a l'etapa de pre-tractament. El cas d'estudi seleccionat va ser l'ETAP de Sant Joan Despí (Barcelona) degut a les seves particularitats: tracta aigua del riu Llobregat, que és un recurs altament variable en termes de qualitat i quantitat, i és un sistema multi-etapa complex. En conseqüència aquest estudi va cobrir un ampli rang de condicions i va permetre portar la tecnologia en qüestió a condicions límit. Els resultats vam mostrar que la UF directa d'aigua crua de riu és capaç de substituir, i resulta competitiva, amb la dioxicloració, coagulació/floculació, decantació i filtració per sorra. La planta pilot va ser capaç de tractar contínuament aigua crua durant 2 anys, independentment de la seva qualitat (ex. terbolesa d'entrada > 1000 NTU), produint aigua de qualitat alta i estable, tant fisicoquímicament com microbiològicament. La majoria dels paràmetres fisicoquímics avaluats van presentar valors inferiors i amb menor variabilitat en l'esquema d'UF directa que en el pre-tractament convencional. Des d'una perspectiva microbiològica, l'esquema d'UF directa avaluat va assegurar una eliminació > 5 log10 unitats de bactèries i virus de tamany superior a 60 nm. El rendiment hídric va oscil.lar entre 94.0-94.7% en condicions òptimes, requerint 1 o 2 contra rentats químics al dia, una pressió transmembrana per sota d'1 bar, fluxos de filtració entre 40-70 L/(m2.h) i un baix consum de reactius químics. En aplicar una micro-coagulació prèvia a la UF, l'increment de la resistència hidràulica durant la filtració va disminuir i es va estabilitzar, l'eficiència del contra rentat va augmentar, i la freqüència dels contra rentats químics va davallar. Degut a que els indicadors d'embrutiment (SDI15 i MFI0.45) del permeat d'UF directa van resultar inferiors als del pretractament convencional, és d'esperar que la unitat següent d'osmosis inversa (OI) precisi menys neteges químiques i per tant, la seva vida útil es prolongui. Addicionalment, a part de l'estalvi econòmic associat a la reducció significativa de reactius dosificats en l'esquema l'UF directa (desinfectants químics i coagulants principalment), es va demostrar una disminució del risc de degradació de les membranes d'OI. Es van dur a terme estudis avaluant els efectes de l'exposició de certs químics (dosificats en el pre-tractament convencional però no en l'UF directa) en les propietats fisicoquímiques i de transport de membranes d'OI. Una caracterització avançada va permetre relacionar els canvis de funcionament de les membranes d'OI amb els seus canvis de composició i d'estructura. La implementació de la UF directa implica que el pre-tractament consisteixi únicament en una etapa de filtració. Això suposa avantatges en termes de complexitat del procés, requeriments d'espai així com d'evitar l'ús de desinfectats químics. Tanmateix, la preservació de les seves propietats de separació al llarg del temps és de gran importància, sobretot des d'un punt de vista microbiològic. En conseqüència, es van definir i dur a terme periòdicament assajos en base a microorganismes per avaluar la integritat de la membrana d'UF directa. Els resultats van indicar que la integritat de la membrana d'UF s'havia preservat durant els 2 anys d'estudi, malgrat les condicions severes que la UF directa va suposar

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47

Lindroos, Magnus. "Utveckling av en kontinuerlig process som renar vatten från läkemedel med hjälp av biopolymertäckta celler". Thesis, KTH, Skolan för bioteknologi (BIO), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172100.

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48

Wei, Chunliang. "Nutrient removal and fouling reduction in electrokinetic membrane bioreactor at various temperatures". Water Science. & Technology, 2009. http://hdl.handle.net/1993/31635.

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With the aim of mitigating membrane fouling, an electrocoagulation (EC) based electrokinetic membrane bioreactor (EMBR) was developed and operated with real municipal wastewater under low temperatures. Both batch tests and continuous EMBR experiments demonstrated the significant advantages in membrane fouling reduction over the conventional antifouling strategies, ushering its potential applications as an attractive hybrid MBR technology for decentralized wastewater treatment in remote cold regions. The main research observations and findings could be summarized as follows: (1). Effective membrane fouling mitigation at low temperatures was due to destruction of extracellular polymeric substances (EPS) and subsequent reduction of the biocake resistance. The transmembrane pressure (TMP) increased at a much slower rate in EMBR and the filtration resistance was about one third of the control MBR prior to chemical cleaning cycle; (2). A new membrane parameter, the specific fouling rate (SFR) was proposed, relating the fouling rate with permeate flux and temperature-dependent viscosity. Pore clogging and biocake resistances were quantified for the first time with the same membrane module and operating conditions as in regular MBR, rather than resorting to the use of batch filtration setups; (3). The floc size in EMBR did not increase as a result of the air scouring shear force and decrease in the extracellular polymeric substances (EPS); (4). When current intensity was less than 0.2 A, polarity reversal had minimal impact on electrode passivation reduction due to insignificant hydrogen yield, however, if current intensity was above 0.2 A, frequent polarity reversal (< 5 min per cycle) was detrimental to electrode passivation if no sufficient mixing was provided; (5). Viability of the microorganisms in the EMBR system was found to be dependent on duration of the current application and current density. The bacterial viability was not significantly affected when the applied current density was less than 6.2 A/m2; (6). Significant abiotic ammonification was found in electrocoagulation (EC). DO in the treated liquid was depleted within an hour, under the anaerobic condition in EC, nitrate was chemometrically reduced to ammonium following a two-step first order reaction kinetics. Aeration (DO > 2 mg/L) was shown effective in suppressing abiotic ammonification; (7). Magnetic resonance imaging (MRI) technology was used for the first time as an in-situ non-invasive imaging tool to observe membrane fouling status in an EMBR.
October 2016

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49

Berg, Josephine. "An Ion-Selective Electrode for Detection of Ammonium in Wastewater Treatment Plants". Thesis, KTH, Kemi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298183.

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Att följa ammonium i reningsverk är avgörande för att förbättra reningsprocessen och kontrollera flödet av föroreningar ut till ekosystemet. Jonselektiva elektroder (ion-selective electrodes, ISEs) är en lovande teknik inom området, där polymermembran baserade på nonactin är de mest studerade membranen för ammoniumsensorer. Membranet droppas tillsammans med ett jon-till-elektron transducerande material på ett elektrodsubstrat av grafit eller glasartat kol. Nonactin-baserade jonselektiva elektroder har typiskt en detektionsgräns inom storleksordningen 10-5 M, men uppvisar betydande kaliuminterferenser. Ett elektrodsystem baserat på grafitelektroder, inkluderande en ISE och en referenselektrod (RE), studerades i detta examensarbete. De jonselektiva elektroderna producerades genom att droppa jon-till-elektron trandsducerande funktionella flerväggiga kolnanotuber (functional multiwalled carbon nanotubes, f-MWCNTs) lösta i tetrahydrofuran (THF) och en membrancocktail innehållande polyvinylklorid (PVC), mjukgörare och nonactin löst i THF på grafitelektroder. Membranet täcktes sedan med en buffrad polyvinylalkohol (PVA) hydrogel med pH 7 och ett gas-permeabelt membran. Referenselektroderna producerades genom att droppa en membrancocktail av polyvinylbutyral (PVB) mättat med NaCl på grafitelektroder. Jonselektiva elektroder med f-MWCNTs som jon-till-elektron transducerande lager och ett PVC-baserat ammonium-selektivt membran med nonactin producerades framgångsrikt. Elektroderna hade en detektionsgräns i storleksordningen 10-5 M, vilket kan jämföras med tidigare artiklar publicerade inom området. Ytterligare producerades PVB-baserade referenselektroder mättade med NaCl framgångsrikt. Referenselektroderna uppvisade små variationer när koncentrationer av olika salt varierades. Arbetet visade att det gaspermeabla membranet Hyflon AD i kombination med en PVA hydrogel inte var lämplig i den föreslagna konfigurationen, då hålrum formades i torkningsprocessen av det gaspermeabla membranet och membranet delaminerade. Det föreslogs att beteendet kunde vara en konsekvens av inkompatibilitet mellan PVC och det gaspermeable membranet, till följd av deras skillnad i polaritet.
Monitoring ammonium in wastewater is vital to improve the treatment process and monitor the release of the pollutant into the ecosystem. Ion-selective electrodes (ISEs) is a promising technique in the area where the ISE is often based on a polymeric membrane containing the ionophore nonactin. The polymeric ion-selective membrane is drop-cast onto graphite or glassy carbon electrode substrates together with an ion-to-electron transducing layer. Nonactin-based ISEs typically demonstrate a limit of detection (LOD) in the range of 10-5 M, but exhibit significant potassium interferences. A solid-state system based on graphite electrodes, including an ISE and a reference electrode (RE), was investigated in this study. The ISEs were produced by drop-casting ion-to-electron transducing functional multi-walled carbon nanotubes (f-MWCNTs) dispersed in tetrahydrofuran (THF) and a membrane cocktail comprising poly(vinyl chloride) (PVC), plasticizer, and nonactin dispersed in THF onto graphite electrodes. The membrane was then covered with a buffered poly(vinyl alcohol) (PVA) hydrogel of pH 7 and a gas-permeable membrane (GPM). The solid-state RE was produced by drop-casting a poly(vinyl butyral) (PVB) membrane cocktail saturated with NaCl onto the graphite electrode. ISEs using f-MWCNTs as ion-to-electron transducers and a PVC-based ammonium-sensitive membrane with nonactin were successfully produced. The electrodes exhibited LODs in the range of 10-5 M, which is comparable to previous articles published on the subject. Additionally, PVB-based solid-state REs saturated with NaCl were successfully produced. The reference electrodes exhibited minor influences when varying the concentrations of various salts. The study showed that the GPM Hyflon AD combined with a PVA hydrogel was not suitable in this configuration, as air voids were formed in the drying process, and the membrane was easily delaminated. It was suggested that this behavior could be a consequence of the incompatibility of PVC and the GPM due to their difference in polarity.

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50

Muya, Francis Ntumba. "Hydrophilic Polysulfone-Hydrogel Membrane Material for Improved Nanofiltration in Wastewater Treatment". University of the Western Cape, 2013. http://hdl.handle.net/11394/4274.

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>Magister Scientiae - MSc
Over the last decade polysulfone membranes have been demonstrated to be one of the best membrane types in wastewater treatment, especially in ultrafiltration, owing to its mechanical robustness, structural and chemical stability. Regrettably these membranes are mostly hydrophobic by nature and therefore highly vulnerable to fouling due to chemosorptive mechanisms. Fouling may be caused by cake formation on the surface of the membrane or by surface assimilation of the foulants. Many studies have been directed at improving hydrophilic properties of polysulfone membranes by introducing different types of nanoparticle composite such as TiO2, ZnO2, Au and Ag nanoparticles to the polymer matrix, in order to reduce fouling potential and increase membrane performance. In the present investigation a hydrogel material was developed by crosslinking polyvinyl alcohol (PVA) with polysulfone (PSF), using glutaraldehyde as crosslinker. PVA has excellent film formation, emulsifying and adhesive properties, it is highly flexible and has high tensile strength. Introducing PVA into the PSF polymer matrix was expected to impart its advantageous properties onto the resulting membrane and enhance hydrophilic characteristics of the membrane. The cross linking of PVA and PSF was controlled at three different ratios to evaluate the effect of the PSF contribution i.e. 25:75, 50:50 and 75:25. The crosslinked polymer composites produced three unique hydrogel materials, which were evaluated for the separation of selected small organic molecules, under hydrodynamic conditions, using rotating disk electrochemistry. The hydrogel thin film behaved as a chemical sensor for the oxidation of tannic acid in aqueous solution, with negligible shift in peak potential as a function of concentration. The nanomaterials prepared were characterised using spectroscopic, morphological and electrochemical techniques. Hydrogel performance in the presence of analyte molecule was evaluated by hydrodynamic voltammetry and electrochemical impedance spectroscopy. From calibration curves based on cyclic voltammetry, hydrodynamic, macroscopic and spectroscopic techniques, the 75% polysulfone and 25 % polyvinyl alcohol hydrogel (75:25 PSF-PVA) presented the best performance for quantitative detection and best sensitivity toward alginic acid and tannic acid than the corresponding composites (50:50 and 25:75 PSF-PVA). Optical results (contact angle) show an agreement with spectroscopic (EC) and microscopic (AFM) result. A decrease in contact angle gives an increase in roughness and diffusion coefficient. High surface roughness was linked to improved hydrophilicity of the polysulfone.

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