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1
Kent, Laura. "Photocatalysts for water purification." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/850035/.
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Advanced water purification methods are required to answer the growing demand for clean water throughout the world. Current methods of removing the pollutants rely on moving the pollutants from one place to another rather than breaking them down. The use of advanced oxidative processes (AOPs) presents a highly effective opportunity to achieve the full mineralisation of pollutants without the added cost of regeneration methods. Photocatalysts, such as titanium dioxide and zinc oxide, can be used as AOPs when activated by electromagnetic radiation in the form of ultraviolet and visible light. To facilitate the activation with visible light, titanium dioxide doped with rare earth elements was produced via a sol gel method. Both single doped and co-doped systems were investigated with efficiency determined by the percentage of degraded methylene blue over 48 hours under ultraviolet filtered visible light. The incorporation of rare earth ions restricted the growth of the more active anatase phase and the method produced highly agglomerated, sintered nano particles which exhibited as micron sized particles. The highest methylene blue removal rate achieved in 48 hours for a single doped system was 70% for the 1 mol% yttrium doped titanium dioxide. This was improved further on inclusion of 1 mol% praseodymium which showed an 86% removal of methylene blue over the same time period. The coating of known up-converting phosphors with the successfully developed doped titanium dioxide was investigated. Yttrium silicate doped with praseodymium and lithium, was found to be the most successful known phosphor when used with the commercially available P25 titanium dioxide. When coated with the doped titanium dioxide shell at a 2:1 ratio of phosphor to titanium dioxide, a methylene blue degradation of 94% was reached. Initial tests on the coating of titanium dioxide with the known up-converting phosphor showed that methylene blue was absorbed rather than broken down so was not developed further. An investigation into the incorporation of zinc oxide, both pure and doped with the same successful titanium dioxide system was carried out. Zinc oxide shells were coated onto doped titanium dioxide, the known up-converting phosphor and the doped titanium dioxide coated known phosphor. The crystalline form of zinc oxide was inhibited by the incorporation of rare earth ions, as with the titanium dioxide system, and from the thickness of the zinc oxide shell. The highest degradation achieved was a 91% removal rate for the ZnO-PrY:TiO2-PrY:Y2SiO5-Pr,Li core shell shell structure indicating there was no further improvement on incorporation of zinc oxide, either doped or un-doped.
2
Lacoursière, Stéphanie. "Water purification by membrane distillation." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26112.
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The objective of this work was to evaluate the technical feasibility of potable water production from both sea water and sodium chloride solutions via the membrane distillation process. Membrane distillation is a thermally driven process in which a hydrophobic microporous membrane separates a hot or warm saline solution from a cold desalinated one. Water, in the form of vapour, migrates from the hot solution to the cold one.Two different hollow fibre membrane distillation modules were used to conduct experiments. Tests were performed to determine the sensitivity of permeate flux and quality to stream temperatures and flowrates, and feed concentration. The hot side temperature was found to have a greater effect on the water flux than the cold side temperature. Water flux values ranged from 0.5 to 1.6 Kg/m$ sp2$hr with salt removals of over 99.99%. A semi-empirical model, based on well established heat and mass transfer correlations, was developed and its predictions were validated with the experimental results.
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Davies, R. H. "Semiconductor photocatalysis for water purification." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636399.
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Although many aspects of the semiconductor photocatalysed mineralisation of water contaminants have been studied by researchers over the past decade, there are still certain areas which need further clarification, if the technique is to be used as an alternative to the presently available methods of water purification. It was the objective of the work in this thesis to provide further understanding of some of these remaining areas. One of the greatest inducements for the introduction of the technique of semiconductor photocatalysed pollutant mineralisation, in preference to the currently available technology, would be an efficiency advantage. The work in Chapter 3, studies the effect of many reaction variables (e.g. T, pH, [TiO2]) in order to provide rate enhancements and therefore further efficiency of the technique. In Chapter 4 the model pollutant, 4-chlorophenol, is used to illustrate the role of activation energies in semiconductor photocatalysed mineralisation reactions, an area which has been largely ignored by researchers in this field to date. In order to speed up the process of reactor designs for commercial semiconductor photocatalysis reactors, there was a need for a predictive kinetic model, to provide information on individual pollutant mineralisation rates, under certain reaction conditions. Chapter 5 outlines a kinetic model which is able to accurately model the mineralisation of various pollutants and can also be used as a predictive tool for non-standard conditions. Chapter 6 enhances this work, to provide a model capable of modelling further pollutant systems, previously unable to be modelled. The technique of semiconductor photocatalysed pollutant mineralisation, will only become a plausible alternative to the currently available technology, if it can be scaled up from the batch reactor level. The work in Chapter 7 aims to provide scale up of the batch system used in Chapter 3 from 2.5 ml to 101.
4
Choi, Siwon (Siwon Chloe). "Microfluidic engineering of water purification." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111415.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
The demand for clean water has been increasing for several reasons, such as rapid industrialization of developing countries, environmental pollution and climate change, and development of biofuels and the resulting irrigation growth. To meet the needs for this growing demand for clean water, desalination has become an appealing solution as saline water (brackish water, seawater and brine) are the most abundant water source for most of the world. However, desalination is energy and capital intensive compared to other water treatment processes, and oftentimes it is not economically feasible. Current desalination technologies require further engineering and development to become more sustainable in the long term. My Ph.D thesis is focused on engineering of electromembrane desalination, which is a set of electrically driven desalination technologies that utilize ion transport through ion exchange membranes. We employed microfluidic platforms and numerical modeling tools for the study, for they help reveal novel insights regarding the micro-scale details that are difficult to be discovered from the conventional large-scale systems. In this thesis, we consider three topics: i) engineering of structures that enhance mass transport in electrodialyis (ED), ii) techno-economic analysis of ion concentration polarization (ICP) desalination for high salinity brine treatment, and iii) development of electrocoagulation (EC) - ion concentration polarization (ICP) desalination hybrid that removes dissolved ions and non-ionic contaminants from water in a single device. First, we employed an electrodialysis (ED) system as a model to investigate the mass transport effects of embedded microstructures, also known as spacers, in electromembrane desalination systems. The spacer engineering is especially critical for low salinity (i.e., brackish water) desalination, where the mass transport in the solution is a dominant contributor to the electrical energy consumption in the system. Parametric studies of the spacer design revealed that small cylindrical structures effectively re-distribute the local flow velocity and enhance mass transport in the system. Furthermore, we found that relative diffusivities of cation and anion in the solution should be considered in designing the spacer and that the optimal design should maximize the mass transport while keeping the effect on the hydrodynamic resistance small. Next, we built an empirical model to estimate an electrical energy consumption of ICP desalination and utilized it to obtain the water cost and optimal operating parameters for high salinity applications. We performed cost analyses on two specific cases (i.e., partial desalination of high salinity brine to the seawater level, and brine concentration for salt production) and compared the performance with mainstream desalination technologies for each application. Lastly, we combined two electrical water treatment technologies and created an EC-ICP hybrid for total water treatment, which removes dissolved ions and non-ionic contaminants from the feed solution. We demonstrated a continuous EC-ICP operation that successfully removed salt and suspended solids. Our system is flexible in terms of the system size, and the type and concentration of contaminants it can handle, and thus it can find applications as a portable water treatment system.
by Siwon Choi.
Ph. D.
5
Lyu, Shicheng. "Membraneless Water Purification via diffusiophoresis." Digital WPI, 2020. https://digitalcommons.wpi.edu/etd-theses/1360.
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Clean water is hard to obtain in certain areas, such as remote locations and during emergency response. Our study developed a membraneless water purification system using diffusiophoresis and tested the influence of various factors (gas pressure, liquid flow rate, etc.) on the turbidity of filtered water. The main component in the separation system is a tube-in-tube-in-tube separator. The inner tube and the middle tube are made of a semipermeable material (Teflon AF-2400), which allows gas (CO2) to permeate through it, but retains liquid (water). In this strategy, the CO2 permeates through the inner tube (the end is sealed) then dissolves into the dirty water/particle suspension passing through the middle tube. It then diffuses radially to the outer tube, where a vacuum collects the CO2, forming a concentration gradient of ions through the water, which induces the migration of charged particles to concentrate at the inner wall of the middle tube. The vacuum phase in the outer tube can increase the concentration gradient of ions in the water and recycle the CO2. Finally, purified water can be collected from the center of the middle tube by a needle in the effluent. The purification system is able to take initial turbid water (243 NTU) to below the WHO drinking water standard (
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Jones, Samuel Casey. "Static mixers for water treatment : a computational fluid dynamics model." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20718.
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Yang, Zi. "INORGANIC MEMBRANES FOR WATER PURIFICATION APPLICATIONS." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1588556057684163.
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Schillo, Melissa C. "Mesoporous Inorganic Membranes for Water Purification." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313586746.
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Baruah, Arabinda. "Smart nanostructured materials for water purification." Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7002.
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Wong, Kit Iong. "Chemical removal of dichloromethane (DCM) from contaminated water using advanced oxidation processes (AOPs) :Hydrogen Peroxide Ozone UV." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3868740.
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Mangombo, Zelo. "The electrogeneration of hydroxyl radicals for water disinfection." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5745_1190373027.
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This study has shown that OHË radicals can be generated in an Fe/O2 cell from the electrode products via Fenton&rsquo
s reaction and used for water disinfection. The cell system in which the experiments were carried out was open and undivided and contained two electrodes with iron (Fe) as the anode and oxygen (O2) gas diffusion electrode. Typically, 100 ml of Na2SO4.10H2O (0.5M) solution was used as a background electrolyte. OHË radicals were produced in-situ in an acidic solution aqueous by oxidation of iron (II), formed by dissolving of the anode, with hydrogen peroxide (H2O2). The H2O2 was electrogenerated by reduction of oxygen using porous reticulated vitreous carbon (RVC) as a catalyst.
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Siguba, Maxhobandile. "The development of appropriate brine electrolysers for disinfection of rural water supplies." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=init_6284_1180438520.
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A comparative study of electrolysers using different anodic materials for the electrolysis of brine (sodium chloride) for the production of sodium hypochlorite as a source of available chlorine for disinfection of rural water supplies has been undertaken. The electrolyser design used was tubular in form, having two chambers i.e. anode inside and cathode outside, separated by a tubular inorganic ceramic membrane. The anode was made of titanium rod coated with a thin layer of platinum and a further coat of metal oxide. The cathode was made of stainless steel wire. An assessment of these electrolysers was undertaken by studying the effects of some variable parameters i.e.current, voltage and sodium chloride concentration. The cobalt electrolyser has been shown to be superior as compared to the ruthenium dioxide and manganese dioxide electrolysers in terms of hypochlorite generation. Analysis of hydroxyl radicals was undertaken since there were claims that these are produced during brine electrolysis. Hydroxyl radical analysis was not successful, since sodium hypochlorite and hypochlorous acid interfere using the analytical method described in this study.
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Hardy, Scott Andrew. "Effectiveness of static mixers for disinfection of cryptosporidium oocysts." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20925.
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Belghazi, A. "Heterogeneous semiconductor UV-photocatalysis for water purification." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636072.
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As traditional disinfection techniques have proved to be inefficient in coping with toxic pollutants, there is a real need to create and develop alternatives such as Advanced Oxidation Processes (AOP's). As one of the most promising AOP's developed to date, heterogeneous semiconductor UV-photocatalysis has been shown to efficiently mineralise and inactivate a wide range of organic, inorganic and biological pollutants. This technique is based on the powerful redox properties of UV-illuminated semiconductors. The photocatalyst (semiconductor), which is insoluble in water, can be used in the form of a dispersion or as a thin coated film over which the pollutant can flow and interact in the liquid as well as in the gas phase. Although many pollutants have been studied, the development of more powerful analytical tools has meant that trace levels of water pollutants such as bromate, a potential carcinogenic by-product of the ozonation process and their destruction needs to be addressed. Chapters Three, Four and Five investigate the development and use of an analytical method for monitoring trace levels of bromate (ppb level or μg.dm-3), in studies involving the use of Granular Activated Carbon (or GAC) and platinised TiO2 (Pt-TiO2) UV-photocatalysis for the removal of this inorganic pollutant. In Chapter Six, a study of TiO2 photocatalysed oxidation of urea-based pesticides is given. Chapter Seven investigates two photoreactor designs for use in flow systems with larger volumes of pollutant which is required if the system is to be commercially viable. These flow photoreactors use thin immobilised films of TiO2 over which the pollutant can flow. Finally, using the flow photoreactor designs studied in Chapter Seven, Chapter Eight presents a study of the photocatalysed oxidation of volatile organic pollutants (or VOC's) in the gas phase.
15
Harries, Richard R. "Water purification by ion exchange mixed beds." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/18591.
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Ion exchange is used extensively for the removal of ionised impurities found in natural waters. The final stage in the production of ultra pure water is normally a bed of mixed anion and cation exchange resins. Three areas within the operating cycle of a regenerable mixed bed - resin separation, resin mixing and anion exchange kinetics - have been investigated. Complete separation of the two resins by backwashing, prior to chemical regeneration, is necessary to prevent the subsequent release of trace impurities into the purified water. Various published models of particle segregation by backwashing were examined but none accurately described the separation of two ion exchange resins with similar bead size distributions and densities. A new model has been proposed based on variations in fluidised bed porosity combined with overlapping bulk circulation cells of particles. A graphical technique has been developed to predict resin separability and the predictions compared with practical data. The effects of variations in bead size, bead density, backwash flow rate and temperature have been calculated. The variations in bead density with ionic form and polymer/matrix type of the exchanger have been measured. Following regeneration the resins are remixed by air agitation of a resin/water slurry. A mechanism to describe the progressive stages of air mixing has been proposed, based on bubble transport and bulk circulation of resin beads. The subsequent sedimentation of the resins was also considered. Laboratory and full scale studies confirmed the predicted effects of mixing fault conditions, particularly re-separation of the mixed resins. A mass transfer equation has been developed to describe the leakage of influent ions through a column of exchange resins. In conjunction with laboratory column tests the equation has been used to investigate the influence on anion exchange of polymer/matrix type, influent anion and the presence of foulants on the resin beads. Sulphate and phosphate ions exchange more slowly than monovalent chloride and nitrate ions. On a fouled exchanger the rate of sulphate exchange deteriorates more rapidly and seriously than for chloride exchange. This has been attributed to steric hindrance of the divalent sulphate ion. A laboratory method has been developed for the routine assessment of mixed bed anion exchangers and the prediction of their performance potential in service, with particular application to condensate purification for boiler feedwater.
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Shen, Junjie. "Application of membrane technologies in water purification." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3147.
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The world is facing a serious water crisis due to rapid population growth, industrialization and climate change. Water purification using membrane technologies provides a promising solution to address this problem. This thesis investigated the feasibility of membrane technologies in a wide range of applications covering drinking water purification and wastewater treatment. Target contaminants included fluoride, natural organic matter (NOM), emerging contaminants bisphenol A (BPA) and cimetidine, and the waterborne parasite Cryptosporidium. The first part of the thesis explored the solute-solute interactions of fluoride and humic substances (HS) in order to understand the behaviour of fluoride in natural water and during membrane filtration processes. It is shown that, at low pH and high ionic strength, fluoride ions are temporarily trapped inside the structure of HS aggregates. The second part of the thesis examined the feasibility of nanofiltration (NF) and reverse osmosis (RO) in treating challenging natural waters in Tanzania containing high fluoride and NOM concentrations, with the aim to increase the availability of drinking water sources. Fluoride retention was found to be dependent on ionic strength and recovery, which was predominantly due to a solution-diffusion mechanism. NOM retention was independent of water matrices but was governed by a size exclusion mechanism. NOM was observed to have a positive impact on fluoride removal. The third part of this work evaluated the on-site performance of a pilot-scale renewable energy powered membrane system in remote areas under varying solar conditions. While the technology is well established, the adaptation to remote areas is far from achieved. The system used in this study reliably produced high-quality drinking water despite of solar fluctuations. This area requires further work in terms of integration, technology adaptation and operation and maintenance schemes. The last part of the thesis reported the development of a series of novel photocatalytic polymers and tested their capabilities in removing wastewater contaminants. The photoactive polymers were highly capable of degrading BPA and cimetidine, as well as inactivating Cryptosporidium. These are very promising materials for simultaneous decontamination and disinfection of wastewater. The results obtained from this thesis provide new insights into solute-solute interactions, solute transport mechanisms, decentralized membrane system and novel membrane materials, which are hoped to contribute to advancements in current membrane technologies.
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Yang, Jingming. "Characteristics of a novel anaerobic fluidized bed reactor for waste water treatment." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/25318.
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Li, June Yonghong. "A study of ozonation kinetics of phenolic compounds in single and solute systems." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/20821.
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Kulati, Thanduxolo Cullinan. "Evaluation of physiochemical qualities and heavy metal levels of the final effluents of some wastewater treatment facilities in the Eastern Cape Province of South Africa." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/1547.
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Water is the most abundant substance in nature and vital for life activities. The major water sources for use are surface water bodies such as rivers and lakes, and underground aquifers and pore spaces down the water table (Ring, 2003). Water derived from these sources is not necessarily pure since it contains dissolved inorganic and organic substances, living organisms (viruses, bacteria, etc). For these reasons, water intended for domestic uses should be free from toxic substances and microorganisms that are of health significance (WHO, 2005). The availability and quality of water always have played an important role in determining the quality of life. Water quality is closely linked to water use and to the state of economic development (Chennakrishnan et al., 2008). Ground and surface waters can be contaminated by several sources. In urban areas, the careless disposal of industrial effluents and other wastes may contribute greatly to the poor quality of water (Mathuthu et al., 1997). In most developing countries, most areas are located on the watersheds which are the end points of effluents discharged from various industries (Oberholster and Ashton, 2008). South Africa, as a developing country, is experiencing rapid demographic changes due to urbanization, industrialization and population growth. The country has also been identified as being water-scarce, which can lead to a challenge of meeting the increasing water demand due to industrialization and urbanization. Such population growth increase may result in an increase in wastewater output, especially around urban areas.
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Khan, Wesaal. "Microbial interactions in drinking water systems." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/53751.
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Thesis (PhD)--Stellenbosch University, 2004.ENGLISH ABSTRACT: Microorganisms show a tendency to accumulate on surfaces in aqueous environments to form biofilms. Microbial biofilms represent a significant problem in public health microbiology as the development of these microbial communities, especially in water distribution systems, may lead to (i) the enhanced growth of opportunistic pathogens, (ii) the development of organoleptic problems, (iii) the reduction in the flow rate and (iv) the regrowth of microorganisms. In this project, biofilm monitors were installed in a large water distribution system to study biofilm phenomena in drinking water systems, and to deduce the biological stability and quality of the potable water. Measurements of biofilm formation potential showed that biofilms did not reach a steady state after 100 to 150 days. The microbial cells in these biofilms were mostly non-culturable. The contribution of the heterotrophic colony count to active biomass, as determined with cell numbers based on ATP measurements were often < 1%, while the ratio of heterotrophic plate counts and direct acridine orange counts were also <1%. The ratio between cell numbers based on ATP measurements and direct acridine orange counts were often < 100%. Results also showed that under certain conditions, such as those investigated in the present study, 1 pg of ATP may not be equal to approximately 104 active bacteria/cells, as stipulated by previous investigations, and that the average ATP content per active bacterial cell is indeed less than 10-16 - 10-15 g. It was calculated that threshold values for assimilable, and dissolved organic carbon below -5 IJg Gil and -0.5 mg Gil, respectively, should be target values for the control of biofilm formation in this system. It was shown that polyethylene, polyvinylchloride, teflon, plexiglass, copper, zinc-coated steel and aluminium provide favourable attachment surfaces that allowed primary colonisation and subsequent biofilm formation. Significant (p < 0.05) differences in surface colonisation on the materials were observed, indicating that the composition of the material has a direct influence on microbial colonisation. The two grades of stainless steel evaluated in this study were the least favourable materials for biofilm formation. It was further demonstrated that the nature of the surface of these materials, flow conditions and water type all had a direct influence on biofilm formation. While modification of the attachment surface did not result in significant differences (p > 0.05) in disinfection efficiency of two commonly used biocides, the concentration of the biocide, as well as the material to which the biofilm is attached, greatly influenced biocidal efficiency. The results show that biofilm monitoring needs to be implemented at the water treatment plants in addition to common biostability measurements.
AFRIKAANSE OPSOMMING: Mikro-organismes neig om te akkumuleer aan oppervlaktes in akwatiese omgewings om biofilms te vorm. Mikrobiese biofilms verteenwoordig In betekenisvolle probleem in publieke gesondheidsmikrobiologie omdat die ontwikkeling van hierdie mikrobiese gemeenskappe in waterverspreidingsisteme mag lei tot (i) die verhoogde groei van opportunistiese patogene, (ii) ontwikkeling van organoleptiese probleme, (iii) die vermindering in die vloeitempo en (iv) die hergroei van mikro-organismes. In hierdie projek was biofilm monitors geïnstalleer in In groot waterverspreidingsisteem om biofilm fenomene in drinkwatersisteme to bestudeer, en om die biologiese stabiliteit en kwaliteit van drinkwater af te lei. Bepalings van biofilmvormingspotensiaal het aangetoon dat biofilms nie In stabiele stadium na 100 tot 150 dae bereik nie. Die mikrobiese selle in hierdie biofilms was meestal niekweekbaar. Die bydrae van die heterotrofiese kolonie tellings tot aktiewe biomassa, soos bepaal deur seltellings gebaseer op ATP metings was dikwels < 1%, terwyl die verhouding van die heterotrofiese plaatteIIings en direkte akridien oranje tellings ook < 1% was. Die verhouding tussen seltellings, gebaseer op ATP metings en direkte akridien oranje tellings was dikwels < 100%. Resultate het ook aangetoon dat onder sekere omstandighede, soos dié wat ondersoek was in die huidige studie, 1 pg ATP nie gelyk is aan min of meer 104 aktiewe bakterieë/selle soos gestipuleer deur vorige ondersoeke nie, en dat die gemiddelde ATP inhoud per aktiewe bakteriële sel inderdaad minder as 10-16 tot 10-15 g is. Dit was bereken dat die drempelwaardes vir assimileerbare en opgeloste organiese koolstof onder -51-1g C/l en -0.5 mg C/l, onderskeidelik, teikens moet wees vir die beheer van biofilmvorming in hierdie sisteem. Dit was aangetoon dat polyetileen, polyvinielchlroried, teflon, plexiglas, koper, sink-bedekte staal en aluminium gunstige aanhegtings oppervlaktes voorsien wat primêre kolonisering en daaropvolgende biofilmvorming toelaat. Betekinisvolle (p <0.05) verskille in oppervlak kolinisering op die materiale was waargeneem, wat aandui dat die samestelling van die materiaal In direkte invloed op mikrobiese kolonisering het. Die twee tipes vlekvryestaal wat geëvalueer was in hierdie studie, was die minder gunstige materiale vir biofilmvorming. Dit was verder gedemonstreer dat die aard van die oppervlak van hierdie materiale, vloeitoestande, en water tipe almal In direkte invloed het op biofilmvorming. Terwyl die aanpassing van aanhegtingsoppervlak nie die ontsrnettinqsdoeltreffendheid resultaat van die twee algemeen-gebruikte biosiede betekinisvol (p > 0.05) beïnvloed het nie, het die konsentrasie van die biosiede doeltreffendheid grootliks beïnvloed. asook die aanhegtings-materiaal, biosied Die resultate het aangetoon dat biofilm monitering geïmplementeer moet word by waterbehandelingsaanlegte as In alternatief vir algemene biostabiliteit metings.
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Lam, Chun-wai Ringo, and 林俊偉. "Development of photocatalytic oxidation technology for purification ofair and water." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38572382.
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Hastie, Michele. "Energy and Water Conservation in Biodiesel Purification Processes." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20384.
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Biodiesel purification processes generate wastewater streams that require a large amount of energy when distillation is used as a treatment technology. Process simulation software was used to show that an alternative water treatment process involving ion exchange would require only 31% of the energy used by distillation. Experiments showed that multiple washing stages were required to meet the standard specification for sodium, an impurity present in crude biodiesel, when washing biodiesel made from used frying oil. A comparison was made between washing biodiesel in a cross-current washing configuration and a counter-current configuration. Both configurations met the specification for sodium within three washing stages; however, the counter-current configuration required less water, making it the more efficient process. Lastly, the removal of sodium from wastewater samples using an ion exchange resin was experimentally investigated. The results validated the use of ion exchange to reduce energy consumption in biodiesel purification.
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Ahmed, Abd El-Safey Ibrahim. "Novel N-halamine Biocidal Polymers for Water Purification." Thesis, University of Surrey, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505994.
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Mole, Jonathan Michael. "Titanium dioxide as a photocatalyst in water purification." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309747.
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Choong, Looh Tchuin (Looh Tchuin Simon). "Application of electrospun fiber membranes in water purification." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98153.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
Electrospun membranes are attractive for the liquid filtration applications especially as microfiltration membranes because they are low in solidity and have open, highly interconnected porous structures. Nevertheless, liquid filtration processes are pressure driven; hence, it is crucial to understand the compressive behaviors of electrospun membranes. Compressive properties of electrospun fiber mats are reported for the first time in this thesis. Membranes of bisphenol-A polysulfone (PSU) and of poly(trimethyl hexamethylene terephthalamide) (PA6(3)T) were electrospun and annealed at a range of temperatures spanning the glass transition temperature of each polymer. The data for applied stress versus solidity of membrane were found to be welldescribed by a power law of the form [sigma]zz =kE([phi]n - [phi]no) where [sigma]-zz is the applied stress and [phi] is solidity, in accord with the analysis of Toll (Polym. Eng Sci., 2004). The values of n range from 3.2 to 6 for PSU and from 8.0 to 20 for PA 6(3)T. The lowest values in each case were exhibited by mats annealed near the glass transition temperature of the fiber material. The higher values of n are attributed to fiber slippage via a mechanism analogous to that of work hardening of metals. The values of kE can vary by an order of magnitude and were difficult to determine precisely, due to the nature of the power law and the inhomogeneity of the mats. The hydraulic permeabilities of electrospun fiber membranes are found to be functions of their compressibilities. Hydraulic permeabilities of electrospun PSU membranes experience a decrease of more than 60% in permeability between 5 and 140 kPa, due to the increase in solidity, attributed to flow-induced compression. This behavior is explained using a simple model based on Darcy's law applied to a compressible, porous medium. Happel's equation is used to model the permeability of the fiber membranes, and Toll's equation is used to model their compressibilities. The permeation model accurately estimates the changes in solidity, and hence the permeability of the electrospun membranes, over a range of pressure differentials. The permeability of commercial phase inversion membrane was higher than those of electrospun membranes at pressures greater than 8 kPa. Microfiltration of emulsions of oil (dodecane) in water using electrospun PA6(3)T membranes was demonstrated. Rejection of the emulsified dodecane decreased from (85 +/- 5) % to (4.3 +/- 0.9) % when the ratio of droplet diameter to fiber diameter (dp/df) decreased from 2.5 +/- 0.4 to 0.57 +/- 0.04, respectively. The normalized flux (relative to the pure water flux) decreased in proportion to the increase in emulsified oil concentration, and decreased with the increase in the total solidity of the membranes. The resistances from the oil were in series with the resistances of the membranes tested. The resistivity of the foulant increased with an increase in the concentration of oil. Foulant deposition models showed that the oil droplets formed a coating that enveloped the fibers. The normalized flux of electrospun membranes was approximately three times higher than that of commercial phase inversion membrane of comparable bubble point diameter, while exhibiting a similar rejection.
by Looh Tchuin (Simon) Choong.
Ph. D.
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Koura, Mbadinga Pauline Joella. "A solar water purification system for rural areas." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2612.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2015.Access to adequate quantities of clean drinking water has become a serious issue on the worldwide level. This is particularly true in arid and rural areas where for the majority of people water is a limited and a vulnerable resource. These water sources which are often highly contaminated are potentially the cause for several diseases (waterborne diseases) and ultimately death especially in infants. Due to poverty and sometimes to the remote conditions of their regions, the population is unable to afford adequate water purification technologies, since they are relatively expensive and energy intensive. It is therefore vital to investigate appropriate water purification technology that people can afford or construct, operate and maintain themselves. A promising technology is solar distillation for the supply of drinking water on a small-scale level. It has proved to be a unique purification method as it can purify almost any type of water by using the high solar energy potential of the affected regions. The most basic form of solar distillation is the use of a single basin single slope solar still. However the downside of this technology is that it presents a low efficiency and productivity. To try to tackle this problem, many studies have been carried out to enhance productivity, effectiveness and efficiency of single-basin solar stills. In this present study, a solar distillation unit was designed, fabricated and experimentally tested. Its performance in terms of distillate output and energy efficiency was analysed under Cape Town conditions and compared to similar stills that have been reported in the literature. The main configuration of the solar still is a double glazed single basin solar still coupled to an external condenser. The study indicated that the performance of the solar still unit can be enhanced by increasing the evaporation rate which is a combined effect of solar radiation, ambient temperature, and the system components temperature. It was concluded that the applied techniques such as the external condenser, double glazing, good insulation and low level of water are effective. The unit was found to have an efficiency ranging between 21 and 29% over the test period and a mean distillate yield of about 2.5 litres per square meter was achieved per day.
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Mechelhoff, Martin. "Electrochemical investigation of electrocoagulation reactors for water purification." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/8896.
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Boahen, Anthony Kwaku. "Purification of oily water with cross flow microfiltration." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311233.
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Neba, Alphonsus. "The Rhodes BioSURE process and the use of sustainability indicators in the development of biological mine water treatment." Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1004043.
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Polluted waters, arising from extensive past and ongoing mining operations in South Africa, pose serious environmental threats to the limited fresh water resource. The long time periods, of decades to centuries, over which decanting mine waters may be expected to flow raises additional concerns about the sustainability of these resources. Responses to the problem have thus increasingly been directed towards the long-term sustainability of mine water treatment technologies (MWTT) as a critical indicator in both their research and development, and application. Bioprocess treatments have been considered in this regard and, among these, the Rhodes BioSURE Process has been investigated in preliminary studies using complex organic carbon wastes as the carbon source and electron donor for the central sulphate reduction unit operation. Although both the mining industry and the related statutory/regulatory authority in South Africa share public commitment to sustainability in the treatment of mine waters, no systematic mechanism has emerged to enable the application of sustainability thinking as a guiding principle in the selection and application of MWTTs, nor in the research and development undertaking. This study undertook the development of a Sustainability Indicator Framework in order to provide a systematic basis for the incorporation of sustainability objectives in MWTT bioprocess development, and specifically to use this framework as an input to the investigation of the scaleup development of the Rhodes BioSURE Process. In the development of the MWTT Sustainability Indicator Framework, an initial survey of industry thinking in this area was undertaken and, based on these outcomes, a detailed questionnaire methodology was developed in order to identify and quantify critical sustainability indicators. These included analysis of environmental, economic, social and technical indicators used in sustainability accounting practice in the industry. Statutory/regulatory sustainability targets in the same categories were derived from State of the Environment Reports (SoER) from Provincial authorities where mining is undertaken in South Africa. A synthesis of industry and SoER values was derived from weighted averages and the Sustainability Indicator Framework based on these outcomes. A Conceptual Decision-Support System, to guide the selection and development of MWTTs, was proposed and also based on these results. In the development of the Rhodes BioSURE Process the use of primary sludge (PS) had been investigated as a potential complex carbon and electron donor source. In this regard the utility operator, and sewage treatment process infrastructure, was identified as potentially meeting aspects of the sustainability objectives identified for MWTT application development. Both the Sustainability Indicator Framework and the Conceptual Decision-Support System provided inputs in the formulation of the experimental programme relating to the scale-up development of the Rhodes BioSURE Process. Based on these outcomes, a series of single- and multi-stage reactor configuration, optimisation and enzymology studies were undertaken at bench-, pilot- and technical-scale operations. These units were operated at hydraulic retention times (HRT) ranging between 22 to 72 hours and at chemical oxygen demand to sulphate ratios (COD:SO[subscript 4]) ranging between 1:1 to 2:1. Studies undertaken in fed-batch, bench-scale reactors confirmed the preliminary feasibility of using established sewage treatment infrastructure as a replacement for novel reactor configurations that had been used in the initial studies. The results further indicated that the hydrolysis of PS occurred at different rates under biosulphidogenic conditions in the different reactor configurations investigated. Scale-up of these findings in multi-stage pilot- (7.4m[superscript 3]) and technical-scale plants (680m[superscript 3]) showed comparable performances between the unit operations in terms of SO[subscript 4] and COD removal. These results indicated no apparent advantages in the uncoupling of hydrolysis and sulphate reduction in separate unit operations as had been suggested in previous studies. Scale-down/scale-up studies were undertaken in a continuously fed single-stage reactor configuration and showed that the process could be effectively operated in this way. Previous proposals that chemical and biological gradients established in the sludge bed of the Recycling Sludge Bed Reactor (RSBR) exercised an influence on the rates of substrate hydrolysis were investigated and the relative activity of α- and β-glucosidase and protease enzymes was measured. Results provided additional support for this hypothesis and it was shown that enzyme assay may also provide a useful tool in process development and monitoring studies. While sulphide recovery, following the sulphate reduction step in the BioSURE Process, was not investigated as a component of this study, the treatment of final effluent or waste spills was identified as an important sustainability requirement given the toxicity of sulphide to human and ecosystem environments. A conventional trickle filter reactor system was evaluated for this purpose and showed close to 100% oxidation to sulphate in a short contact time operating regime. Although residual COD removal was low at ~20% of influent, it is considered that high rate recycle biofilter operation could achieve the COD discharge standard of 75 mg/l. The results of the above studies provided inputs into the design, construction and commissioning of the first full-scale commercial application of the Rhodes BioSURE Process for mine wastewater treatment using sewage sludge as the carbon and electron donor source. An adjacent mine and sewage works have been linked by pipeline and an operational capacity of 10 Ml/day water treated has been established with sulphate reduced from ~1300mg/l to <200mg/l. These developments constitute a novel contribution in the mine waste water treatment field.
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Richman, Marjorie Timmerly. "Particle and biomass detachment during biological filter backwashing : impact of water chemistry and backwash method." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19519.
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Skeens, Brian Michael. "Pilot scale evaluation and comparison of static mixers for coagulation in water treatment." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19522.
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Conley, LuAnne Simpson. "Removal of complexed iron by chemical oxidation and/or alum coagulation." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03172010-020643/.
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Jeffcoat, Stuart Blakely. "The importance of hydrophobicity/hydrophilicity on particle removal in deep bed filtration and macroscopic filtration modeling." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/20149.
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Weinberg, Marla Kaye. "The effectiveness of an electrochemical treatment process and its applications in textile wastewater treatment." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/8697.
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Shah, Anup G. "Fate and effect of the antioxidant ethoxyquin on a mixed methanogenic culture." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/19904.
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Omoniyi, Emmanuel Oluseyi. "Comparative study of brine treatment using a functionalized nanofibre and an ion exchange resin." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2334.
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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2015.In this study, comparative sorption studies of the major metal ions (Mg2+, Ca2+, K+ and Na+) in the brine wastewater were performed on hydrophilic materials (PAN nanofibre, PAN+TiO2 nanofibre, PAN+ZEOLITE nanofibre) and Purolite S950 resin to investigate their uptake performances. For this purpose, PAN nanofibre was electrospun and subsequently doped with 3 wt% each of titanium dioxide and zeolite respectively, in controlled experimental conditions in order to improve its performance. This was followed by the characterization of the respective hydrophilic materials (PAN, PAN+TiO2 and PAN+ZEOLITE nanofibres) using Fourier Transform Infrared Spectroscopy (FT-IR); Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). SEM showed that the incorporation of titanium dioxide or zeolite into the PAN structure made the surface rougher than that of the ordinary PAN nanofibre and FT-IR revealed the peaks belonging to titanium dioxide and zeolite respectively, showing the inorganic materials are within the PAN structure. The XRD analysis complemented the FT-IR of the nanofibres by revealing the peaks characteristic of titanium dioxide and zeolite are present on the PAN structure.
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Liu, Jinlin, and 刘金林. "Wastewater organic as the precursors of disinfection byproducts in drinking water: characterization,biotransformation and treatment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46289562.
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Santoyo-Gutierrez, Socrates. "Absorption heat pump assisted effluent purification." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245055.
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Bach, Altai. "Water purification by advanced oxidation processes using nano particles." Online version, 2010. http://dds.crl.edu/CRLdelivery.asp?tid=13238.
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Rodríguez, Rodríguez Juan Martín. "Sputter deposited titanium oxide films for photoelectrochemical water purification." Universidad Nacional de Ingeniería. Programa Cybertesis PERÚ, 2000. http://cybertesis.uni.edu.pe/uni/2000/rodriguez_rj/html/index-frames.html.
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Non-stoichiometric polycrystalline Ti oxide thin films were prepared by reactive DC magnetron sputtering of Ti in Q2+Ar. Sputtered Ti oxide samples with four values of the film thickness were investigated by transmission electron microscopy (TEM) Cross-sections of (he specimens shows thai iheir most salienl feature is a parallel penniform structure extending over che fall cross-sections of the films. A very large intemal surface is manifest Rutile and anatase phase films were obtained by heating the substraia during the deposition. Incident photon-to-currem efficiency (IPCE) was studied as a function of several spuuenng parameters such as temperature of the substrate, film thickness, and 02/Ar gas flow ratio. The IPCE increased as the crystallinity of Ti oxide was systematically varied from amorphous to a mixture of analise and rutile, and it was also enhanced in films depositad at !ow O2/Ar ratios. The photogenerated current was found to be highly dependen on the composition, thickness, and structure of Ti oxide films. Optical constans of the films were determined from spectrophotometric measuremems of reflectante and transmittance. The amorphous films had a band gap of -3.4 cV and a wide absorption tail extending 10 lower energics. The crystalime films displayed a band gap of 3,3-3.35 eV and a more narrow absorption tail. The optical constants were dependem on film ihickness The crystalline films showed evidence of structural inhomogeneilics Icading to diffuse scatiering in the thicker films as well as to a grading of the refraciive Index. The complex dielectric permittivity £ was determined in the 10'3 to 107 H2 range from measurements using a capacitor configuration. The real and imaginary parts of s displayed power-law dependencies from - 10 Hz up to a value between 1 and 10 kHz, Our data could be rationalized in terms of a model for screened hopping of vacancy-inouced charge carriers, but details remain poorly undcrstood. The internal surface area was enhanced with increasing film ihickness, and that property could be correlated with an enlarged photoelectric conversión eficiency. Ti oxide films with thicknesses in the 1,9-8.0-mm range were sputter deposited orno etectrically conductive transparenl glass substrates. X-ray diftraction indicated a dominating rutile structure. The films were used to investigate photo-electrocatalytic degradation of 4-chlorophenol in water solution, employing a specially designed reactor. ITV light was used for (he photocatalysis, and a bias potential was applied for avoiding electron-hole recombination. The photocurrent and the kineiics of the catalytic reaaion were tested with potentiosiatic and spectrophotometric measurements, The reaction producis were investigated using different arrangements of a Ti oxide working electrode and a Pt counter electrode, IA irradiation through the gfass substrate yielded an enhancement of the reaction kinetics for increased film thicknesses and applied bias potential. X-ray diffractomeiry showed that nitile-like and anatase-Hke films were produced depending on the oxygen conteni in the sputter plasma. Rutherford backscatiering spectrometry documented some oxygen overstoichiometry. Spectral optical measurements were used to analyze the absorption around ihe fundamentari band gap and lo give evidence of some hydration and hydroxylation in ihe films. The various Ti oxide films were broughi in contact wiih 4--chlorophenol (4-CP), whose photo-electrocatlytically induced degradation under ukraviolet irradiation was investigated in a reacior allowing optical probing of 4-CP as well as of intermediate reaction products such as benzoquinone. A miile-üke structure was conductive to the degradation of 4-CP, which can be reconciled with the band gap being suitable for producing photoinduced heles capable 10 effecting oxidation of the pollutant.
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John, Wilson. "Synthesis, properties and analysis of polydadmac for water purification." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/19531.
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Thesis (PhD)--Stellenbosch University, 2008.ENGLISH ABSTRACT: This study concerns the synthesis, properties and quantitative analysis of polydiallyldimethylammonium chloride (polyDADMAC), a water-soluble polymer used world-wide for potable water purification. The special interest in this polymer is the result of its widespread use and the current lack of adequate analytical methods for it. This is especially important for water treatment organisations. A novel gel permeation chromatography (GPC) method was developed and evaluated for polymer analysis. The scope was extended to determine the presence of unreacted monomer (DADMAC) as well as the percentage active polymer. polyDADMAC was first prepared using a known synthesis method. The product was purified and characterized by GPC and 13C-NMR spectroscopy. New and conclusive evidence of the existence of a five-member pyrrolidine ring system was obtained. A proposed mechanism of polymerization was determined. The activity of the synthesized polyDADMAC was evaluated and it was found to perform effectively as a coagulant. The physical and chemical properties of polyDADMAC were then studied under simulated water treatment conditions. The polymer reaction with chlorine revealed the formation of trihalogenated methane compounds (THMs). Gas chromatography–mass spectrometry (GC–MS) was used to conclusively identify the formation of chloroform. The polymer stability under different conditions of heat exposure, UV radiation and pH variations was studied. GPC results indicated that polyDADMAC is a very stable polymer and undergoes structural change only when subjected to extremes of pH, temperature and UV conditions. Results of a short study on microbial degradation indicated growth of the cultures, and subsequent polymer degradation. Reactions of polyDADMAC were concluded with a study of the impact of ozone on polyDADMAC. GPC results indicated a significant change in the ozonated polymer peak profile. Analytical methods to determine polyDADMAC residues in water were reviewed and critically evaluated. Methods based on complex formation/spectroscopy suffered from severe limitations and produced no meaningful results, contrary to claims made by previous researchers. Colloid titration based on an established method was promising but required extensive modification for quantitative analysis. Finally four novel methods were developed, including: solid phase extraction, membrane filtration-GPC, the HACH complexation method, and a GPC method with indirect UV detection. The study is concluded with a chemical risk assessment that indicated minimal human health risks associated with the production and use of polyDADMAC.
AFRIKAANSE OPSOMMING:Hierdie studie behels die sintese, eienskappe en kwantitatiewe analise van polidiallielmetielammoniumchloried (polyDADMAC), 'n wateroplosbare polimeer wat wêreldwyd vir drinkwatersuiwering gebruik word. Die belangstelling in hierdie spesifieke polimeer is as gevolg van die wydverspreide gebruik daarvan en die feit dat daar tans onvoldoende eenvoudige analitiese metodes daarvoor bestaan. Dit is veral belangrik vir waterbehandelingsorganisasies. 'n Nuwe gelpermeasiechromatografie (GPC) metode is ontwikkel en geevalueer vir die analise van hierdie polimeer. Die omvang van die studie is later uitgebrei om die teenwoordigheid van ongereageerde monomeer (DADMAC) asook die persentasie aktiewe polimeer te bepaal. polyDADMAC is eers volgens 'n bekende sintesemetode berei. Die produk is gesuiwer en gekarakteriseer m.b.v. GPC en 13C-KMR. Nuwe bewyse vir die bestaan van 'n vyflid pirollidoonringsisteem is verkry. 'n Meganisme vir hierdie polimerisasie metode is vasgestel. Die aktiwiteit van die bereide polyDADMAC is geevalueer en daar is bevind dat dit effektief as koaguleermiddel optree. Daarna is die chemiese en fisiese eienskappe van polyDADMAC onder gesimuleerde waterbehandelingskondisies bepaal. polyDADMAC het met chloor gerageer om trihalogeneerde metaanverbindings (THMs) te vorm. Gaschromatografie–massa-spektrometrie (GC–MS) is gebruik om die ontstaan van chloroform te bevestig. Daarna is die stabiliteit van die polimeer onder verskei reaksiekondisies bepaal: hitte, UV-bestraling, en pH. GPC-resultate het aangeduiui dat polyDADMAC baie stabiel is en ondergaan strukturele veranderings slegs onder uiterste kondisies van pH, temperatuur en UV. 'n Kort studie van die effek van mikro-organismes op polyDADMAC het egtermikrobiese kultuurgroei met die gevolglike afbreek van die polimeer getoon. Resultate van 'n studie van die impak van osoon op polyDADMAC het getoon dat daar 'n groot verandering in die GPC-profiel van die ge-osoneerde vorm van die polimeer was. Verdere analitiese metodes wat al gebruik is om polyDADMAC residue in water te bepaal, is uitgevoer en krities geevalueer. Metodes gebasseer op kompleksvorming/ spektroskopie het erge beperkings gehad en het nie betekenisvolle resultate gelewer nie. Dit was in teenstelling met wat voorheen deur ander navorsers bevind is. 'n Kolloiedtitrasie gebasseer op 'n bestaande metode het goeie resultate gelewer maar het omvattende veranderings benodig om kwantitatiewe resultate te lewer. Ten slotte is vier nuwe metodes ontwikkel: soliede fase-ekstraksie, membraanfiltrasie-GPC, die HACH-komplekseringsmetode, en 'n GPC-metode met indirekte UV-waarneming.. Die studie is afgesluit met 'n bepaling van die chemiese risiko wat poly DADMAC vir die gesondheid van die mens inhou. Daar is tot die gevolgtrekking gekom dat die produksie en gebruik van poly DADMAC slegs‘n minimum gesondheidsrisiko inhou.
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De, Villiers David. "Design and evaluation of photocatalytic reactors for water purification." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52178.
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Thesis (PhD)--Stellenbosch University, 2001.ENGLISH ABSTRACT: The photo-mineralization of organic compounds (in the combined presence of a Ti02 based semiconductor catalyst, UV radiation and molecular oxygen) represents an advanced oxidation technology with significant potential for environmental pollution abatement. This oxidation process (generally known as photocatalytic oxidation - PCO) is currently the subject of extensive global research, with the main objective being the oxidative removal of organic and inorganic pollutants from water, air and soil. Presently, many barriers still block the way to commercial implementation of this technology, hence a unique (and effective) configuration of catalyst, light source and reactor design needs to identified. In terms of the water treatment scenario (which is the emphasis of this work) the need exists to develop a practical and affordable PCO reactor for water treatment on a large scale. The two laboratory-scale PCO reactors investigated in this work were based on a "falling film" flow reactor design and were constructed with commercially available materials and components. Degussa P-25 Ti02 was used as semiconductor catalyst and two types of low-pressure mercury lamps as the UV light source. Three modes of operation were investigated in order to determine the practical feasibility of the reactors. These included the recirculation, single pass and sequential single pass modes. The reactors were operated either as a Ti02 slurry-phase reactor (Reactor 1), or with Ti02 immobilized on stationary fiber glass and fibrous activated carbon sheet modules (Reactors 2A and 28 respectively). Extensive parametric evaluations were done using conventional one-factor variation and statistical methods according to optimal experimental design principles. The PCO treatment of two model organic pollutants (para-Chlorophenol and cyanobacterial microcystin YA, YR, LR and RR) were investigated. These pollutants were spiked into various water matrices to the desired concentration level. The combined photocatalyticcarbon adsorption treatment of these two pollutants was also investigated in Reactor 28. The experimental results obtained through this work showed that both model pollutants were successfully degraded in several water matrices by means of treatment in the respective PCO reactors. Moreover, this research was the first ever demonstration of the Ti02 photocatalytic degradation of microcystin toxins in the aqueous phase. The large number of parametric and optimization studies yielded the relative contributions of the various process parameters (in terms of the defined photocatalytic efficiency parameters as responses) very effectively. Furthermore, statistical evaluation of the experimental data provided valuable insight into the scientific phenomena associated with Ti02 mediated PCO processes.
AFRIKAANSE OPSOMMING: Die foto-mineralisasie van organiese verbindings (in die gekombineerde teenwoordigheid van 'n Ti02 gebaseerde halfgeleier katalisator, UV straling en molekulêre suurstof) verteenwoordig 'n gevorderde oksidasie-tegnologie met beduidende potensiaal vir bekamping van omgewingsbesoedeling. Hierdie oksidasie-proses (algemeen bekend as fotokatalitiese oksidasie - FKO) is tans wêreldwyd die onderwerp van ekstensiewe navorsing, met hoofdoel die oksidatiewe verwydering van organiese en anorganiese besoedelingstowwe uit water, lug en grond. Huidiglik bestaan daar nog vele struikelblokke wat die weg na kommersiële implementering van hierdie tegnologie blokkeer, gevolglik moet 'n unieke (en effektiewe) konfigurasie van katalisator, ligbron en reaktor-ontwerp nog identifiseer word. In terme van die waterbehandeling situasie (wat die klem van hierdie werk is) bestaan die nodigheid om 'n praktiese en bekostigbare FKO reaktor te ontwikkel vir watersuiwering op 'n groot skaal. Die twee laboratorium-skaal FKO reaktore in hierdie studie was gebaseer op 'n "vallende film" vloeireaktor ontwerp en is gekonstrueer met kommersieël beskikbare materiale en komponente. Degussa P-25 Ti02 is aangewend as halfgeleier katalisator en twee tipes lae-druk kwik lampe as die UV ligbron. Drie bedryfsmodes is ondersoek met die doel om die praktiese haalbaarheid van die reaktore te bepaal. Hierdie het ingesluit die resirkulasie, enkeldeurvloei en enkeldeurvloei-sekwensie modes. Die reaktore is bedryf as óf 'n Ti02 flodder-fase reaktor (Reaktor 1) óf met Ti02 ge-immobiliseer op 'n stasionêre veselglas en veselagtige ge-aktiveerde koolstof blad-modules (Reaktor 2A en 28 onderskeidelik). Omvattende parametriese evaluasies is gedoen deur gebruik te maak van konvensionele een-faktor variasie en statistiese metodes na aanleiding van optimale eksperimentele ontwerp beginsels. Die FKO behandeling van twee modelorganiese besoedelingstowwe (para-Chlorofenol en siano-bakteriese mikrosistien YA, YR, LR en RR) is ondersoek. Hierdie besoedelingstowwe is ge-ent in verskeie watermatrikse tot die verlangde konsentrasievlak. Die gekombineerde fotokatalitiese - aktiveerde koolstof behandeling van die twee besoedelingstowwe is ook ondersoek in Reaktor 28. Die eksperimentele resultate verkry deur hierdie werk het getoon dat beide die modelbesoedelingstowwe suksesvol gedegradeer is in verskeie watermatrikse deur behandeling in die onderskeie FKO reaktore. Trouens, hierdie navorsing was die eerste demonstrasie ooit van die Ti02 fotokatalitiese degradasie van mikrosistien toksiene in die waterige fase. Die groot aantal parametriese en optimiseringstudies het die bydraes van die verskeie proses-parameters (in terme van die gedefinieerde fotokatalitiese effektiwiteitsparameters as response) baie effektief verskaf. Verder, statistiese evaluasie van die eksperimentele data het waardevolle insig verskaf tot die wetenskaplike verskynsels te assosieer met Ti02 gemedieërde FKO prosesse.
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Vasylchenko, D. "The study and analysis of various water purification methods." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45938.
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Water has always been an important and life-sustaining drink to humans and is essential for the survival of all known organisms. Though water is available in plenty, in the present day scenario availability of pure drinking water has become a rare commodity that is attributed to a number of known reasons.
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Haikola, Matilda, and David Fridlund. "District Heat-driven Membrane Distillation for Drinking Water Purification." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232824.
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The demand for clean and accessible water is growing worldwide due to population growth and still millions are without this necessity. Urban areas are developing rapidly but adequate water is frequently a deficiency in these areas. Bottled water is often the solution to this problem but a more thoughtful alternative in terms of cost and environmental impact would be preferable. Membrane distillation presents as an alternative for this problem. Membrane distillation is a thermally driven water purification process which requires heat as an energy source. A source of heat which have become more widespread in urban areas today is district heating. The integration of membrane distillation with district heating could therefore provide an environmentally and economically sustainable solution for clean and accessible water. This thesis presents a techno-economic and environmental analysis of a potential integration of a membrane distillation unit with district heating network. The focus of the study has been on finding and evaluating costs for a membrane distillation system integrated with district heating as well as examining the environmental impact from the purification process. The study use Germany as a case example for the integration and commercialization of membrane distillation technology as the country have a developed district heating network in urban areas and a high consumption of bottled water. The findings from the study is that, for the system design employed, the cost for water purified with membrane distillation is $0.0111/litre, which is cheaper than the average price of bottled water in Germany ($0.3/litre). The environmental impact for water purified with membrane distillation is 0.024 kg CO2e/litre, which is significantly lower than the environmental impact from bottled water (0.225 kg CO2e/litre).Efterfrågan av rent vatten ökar globalt på grund av befolkningstillväxt och fortfarande är miljoner människor utan denna nödvändighet. Stadsområden utvecklas snabbt, men dricksvatten är ofta en brist i dessa områden. Flaskvatten är ofta lösningen på problemet, men ett mer genomtänkt alternativ med avseende på kostnad och miljöpåverkan skulle vara att föredra. Membrandestillation presenterar sig som ett alternativ för detta problem. Membrandestillation är en termiskt driven vattenreningsprocess som kräver värme som energikälla. En värmekälla som har blivit mer utbredd i stadsområden idag är fjärrvärme. En integrering av membrandestillation med fjärrvärme kan därför ge en miljömässig och ekonomisk hållbar lösning för rent dricksvatten. Denna avhandling presenterar en teknoekonomisk analys med ett miljöperspektiv av en potentiell integration av en membrandestillationsenhet med fjärrvärmenätet. Rapportens fokus har varit på att hitta och utvärdera kostnader för ett membrandestillationssystem integrerat med fjärrvärme samt att undersöka miljöpåverkan från reningsprocessen. Studien använder Tyskland som ett exempel på land för integration och kommersialisering av membrandestillationstekniken. Detta eftersom landet har ett välutvecklat fjärrvärmenät i stadsområden och en hög konsumtion av flaskvatten. Resultaten från rapporten är att kostnaden för vatten renat med membrandestillation, för den systemkonstruktion som använts, är 0,0111 USD/liter, vilket är billigare än genomsnittspriset för flaskvatten i Tyskland (0,3 USD/liter). Miljöpåverkan för vatten renat med membrandestillation är 0,024 kg CO2e/liter, vilket är lägre än miljöpåverkan från flaskvatten (0,225 kg CO2e/liter)
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Shafieian, Dastjerdi Abdellah. "A solar‐driven membrane‐based water desalination/purification system." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2323.
Full textAbstract:
Lack of fresh water has turned into one of the major challenges of the world in the present century. Desalination of brackish or seawater has been proven to be one of the best solutions to cope with this global challenge. Among all the desalination methods, Membrane Distillation (MD) is well known as a cost effective and profitable technology for treating saline water. However, higher energy consumption compared to other separation techniques has been reported as MD’s main drawback. That is why the application of solar energy to provide the thermal energy requirement of MD modules has been the focal point of research in this field in recent years. Despite many studies and efforts that have been conducted to date, solar driven membrane based
systems have still many undiscussed aspects. Integrating solar energy and membrane technology is not yet a straightforward matter and has many opportunities for technical and economic improvements. Utilizing new solar technologies, their combination with thermal driven membrane modules, and trying to improve thermal and overall efficiency of this integration can be the bedrock of novel researches. Furthermore, most of the previous studies and research activities have been focused on desalination systems, while the proposed systems have been either inefficient or energy intensive, and other sources for improving water quality such as wastewater is completely under-researched. That is why, this study proposed a novel integrated solar membrane-based desalination and wastewater treatment system taking advantage of technologies such as heat pipes, vacuum tubes, and direct contact membrane distillation (DCMD) modules.
A theoretical study was considered to firstly investigate the performance and feasibility of the proposed system and secondly to obtain the optimum physical and operational characteristics of both solar and desalination systems. The theoretical analysis was performed by using appropriate energy and exergy equations which were solved in Matlab software. Heat and mass transfer equations along with energy and mass balance equations were considered in this study. A new multi-step theoretical approach was proposed and developed to model the DCMD unit, while the thermal resistance network method was applied in the simulation of the solar system including vacuum glasses, heat pipes, and manifold.
Based on the optimum data obtained from the mathematical models, an experimental rig was designed, manufactured, and tested under different climatic and operational conditions. The system was controlled using a central control unit including a control unit, a National Instrument Data Acquisition (NI-DAQ) system, and a power unit. An application program interface (API) was programmed in the LabVIEW 2014 software to record the data at 10- second intervals. Climatic data including solar radiation, ambient temperature, and wind velocity were collected from the weather station located at Edith Cowan University, Joondalup Campus which is located 23 km north of Perth business district.
The comparison of the theoretical and experimental results revealed the capability of the developed model to accurately predict the performance of the proposed system. In addition, the optimum characteristics of the system, including the optimum solar collector’s surface area, feed and permeate streams mass flow rates and temperatures, were determined. The results revealed that the application of this nanofluid as the solar working fluid along with implementing a variable mass flow rate technique significantly improved the overall efficiency of the solar system. Sodium Dodecyl BenzeneSulfonate (SDBS) at 0.1 wt.% was the optimum concentration of SDBS for 0.05 wt.% Al2O3/DI water nanofluid exhibiting the highest stability and thermal conductivity enhancement. The results also showed the high dependency of the DCMD module to the physical (e.g., length) and operational (e.g., feed and permeate mass flow rates) parameters, while its performance was independent of salinity. The highest freshwater production rates in hot and cold seasons were observed to be 3.81 and 2.1 L/m2h, respectively. Moreover, the maximum gained output ratios of the system were around 0.79 and 0.58 in hot and cold seasons, respectively.
The results also indicated that the gained output ratio and overall efficiency of the system improved upon application of a cooling unit in the permeate flow loop of the system, indicating the effectiveness of the proposed configuration. In addition, the freshwater production increased up to 37% when the system was equipped with a cooling unit. However, the economic feasibility of implementing the cooling unit needs further investigations. Moreover, the proposed system effectively removed the contaminating metals from wastewater by showing the removal percentage of 96, 89, 96, 100, 100, and 94% for Fe, Mn, Cu, Na, K, and Ca, respectively.
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Isaeva, Margarita, and Castro Natasha Montes. "Water Treatment for the Removal of Iron and Manganese." Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-5357.
Full textAbstract:
The purpose of the study is to find a suitable method for removal of iron and manganese considering local economic and environmental aspects. El Salvador is situated in Central America with a coast line towards the Pacific Ocean. The country borders Guatemala and Honduras. Aguilares is a town situated in the department of San Salvador, with a population of approximately 33,000 people. Currently, the population is provided with water for about two hours per day, since it is the highest capacity of the existing wells. During these two hours many households fill a small tank with water to use for the remainder of the day. The water is not safe to use for oral consumption because of the levels of bacteria and other contamination. One of the wells, situated in the community of Florída is not in use at this date because of the high levels of Iron and Manganese in the ground water which cannot be removed with the present technique.Ground water is naturally pure from bacteria at a depth of 30 m or more, however solved metals may occur and if the levels are too high the water is unsuitable to drink. The recommended maximum levels by WHO (2008) [1] for Iron and Manganese are 2 mg/l and 0.5 mg/l respectively.Literature and field studies led to the following results; Iron and manganese can be removed by precipitation followed by separation. Precipitation is achieved by aeration, oxygenation or chemical oxidation and separation is achieved by filtration or sedimentation.The different methods all have advantages and disadvantages. However the conclusion reached in this report is that aeration and filtration should be used in the case of Florída. What equipment and construction that should be used depends on economic and resource factors as well as water requirements, which is up to the council of Aguilares to deliberate.
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Wang, Po-Yang, and 王伯洋. "Water purification of brackish water aquaculture." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/85210277667013176328.
Full textAbstract:
碩士崑山科技大學
環境工程研究所
105
A water purification testing site for saltwater fishponds was established in Cieding, Kaohsiung, to promote the application of water purification technology and improve water quality of fishponds. Water circulation and purification in fishponds was accomplished by external water purification ponds and internal cultivation of saltwater aquatic plants and algae. The experimental fishponds had an area of approximately 1942 m2, average depth of 1.8 m, whereas the effective volume of the water purification pond was 55 m3. The water purification system was powered by a 2 hP pump, the hydraulic retention time of the water purification pond was 2.75 h, and the daily energy consumption was 17.9 kWH. Aquatic plants with water purification abilities were cultivated in the water purification pond. Water quality of the fishpond was monitored continuously by a multiparameter water quality monitoring device. The monitored items included dissolved oxygen, pH, water temperature, conductivity, and redox potential. In addition, regular sampling was performed to test the ammonia nitrogen, suspended solids, and water turbidity. In 2015, the mean concentration of ammonia nitrogen was 0.64 mg/L, which was a 46% decrease compared to that of the unpurified control (1.20 mg/L). The overall energy-saving effect was up to 6.5%. In addition, under similar rearing conditions, the mean weight of each milkfish reared in the purified fishpond was 15.3 tael, which was a 36.6% increase compared to that of the control group (11.2 tael). In 2016, due to the effects of temperature stratification, the mean concentration of ammonia nitrogen was 0.45 mg/L, which was a 21% decrease compared to that of the unpurified control (0.57 mg/L). The overall energy-saving effect remained at 6.5%. Furthermore, under similar rearing conditions, the mean weight of each milkfish reared in the purified fishpond was 22.4 tael, which was a 10.7% increase compared to the 20 tael of the control group (harvest delayed by four months). The effectiveness of the fishpond water purification was very significant. This fishpond water purification technology can be applied to improve the water quality of fishponds and reduce the risks of aquaculture.
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Loeb, Stephanie. "Nanostructured Photocatalysis for Water Purification." Thesis, 2013. http://hdl.handle.net/1807/43101.
Full textAbstract:
The integration of photocatalytic advanced oxidation into solar disinfection is a robust method of improving the microbial and chemical quality of treated water. This study evaluates the performance of photocatalytic solar irradiated batch reactors through an analytical model that reduces treatment parameters by simplifying photoreactor geometry and relating performance to reactor configuration. Accompanying experiments compare the performance of titanium dioxide coated foams of varying pore size to suspended and fixed film configurations through degradation of organic dyes (acid orange 24 and methylene blue), Escherichia coli, and 1,4-dioxane. Results indicate that a catalyst immobilized on a foam support can match the performance of a suspension due to effective mass transport and association between analyte and foam. Additionally, the potential treatment capacity of solar photocatalysis was compared to conventional treatment methods. Results of this comparison stress the fundamental limitation of solar photocatalysis if visible light wavelengths are not harnessed.
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Lin, Jia-Bao, and 林嘉寶. "DMAIC PLUS-Water purification Case." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/07088727433805232391.
Full textAbstract:
碩士國立勤益科技大學
工業工程與管理系
100
This study proposes DMAIC PLUS (DMAIC+) as the improvement of DMIAC approach to reinforce DMAIC when there is an unexpected accident. A case study contained three water factories that illustrate the purification process is adopted to explain and verify our proposal. DMAIC+ concept is applied when there is a sudden of high turbidity water during the water resource purification process where progress can be tightly tracked and monitored, and in turn safe drinking water standards can be reached with effectiveness.
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CHEN, WEI-LIN, and 陳威霖. "Water purification of freshwater aquaculture." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/88b6rz.
Full textAbstract:
碩士崑山科技大學
環境工程研究所
107
In this study, a freshwater fish farm in Xuejia, Tainan, with an area of 2,060 m2 and a depth of 1.5 m, was used for the investigation of water purification. total of two identical channels with an effective volume of 3.3 m3, and a hydraulic retention time of 1.12 hr was used for the purification of contaminated fish farm water. The water purification system was powered by a 1 HP pump. Different aquatic plants were grown to purify the fish farm water, including emergent plant Da’an water jacket (Hygrophila pogonocalyx Hayata, 2016 test run); submerged aquatic plant hornwort (Ceratophyllum demersum L., 2017 test run); and floating aquatic plant water hyacinth (Eichhornia crassipes (Mart.) Solms, 2018 test run). In water quality monitoring programs, dissolved oxygen, pH, water temperature, conductivity, redox potential, ammonia nitrogen, suspended solids, nitrite nitrogen, and turbidity, were measured weekly to evaluate the performance of water purification. The results obtained in this study indicated improvement in water quality. During the 2016 test run, Da'an water jackets was used to purify the water, and SS levels in the influent ranged from 10.0 to 44.0 mg/L with an average level of 25.9 mg/L (RSD=25.1%, n=12). After treatment, performance of suspended solid removal was 27.9% During the 2017 test run, Hornwort was used to purify the water, and the ammonia nitrogen levels in the influent ranged from 0.05 to 0.21 mg/L, with an average level of 0.068 mg/L (RSD=63.9%, n=19). After treatment, performance of ammonia nitrogen removal was 11.7%. However, owing to strong growth of algae, hornwort was not able to become dominant. During the 2018 test run, water hyacinth was used to purify the water, and dissolved oxygen in water increased from 6.08 mg/L to 7.82 mg/L. After treatment, the level of nitrite nitrogen decreased from 0.46 mg/L to 0.40 mg/L, performance for nitrite nitrogen removal was 13.0%. The results obtained in this study indicated that the present system do not have good performance for the purification of freshwater aquaculture. A purification channel with longer hydraulic retention time and lower depth of water are suggested.