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Dissertations / Theses on the topic 'Water Purification Disinfection Australia'

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Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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1

Ranmuthugala, Geethanjali Piyawadani. "Disinfection by-products in drinking water and genotoxic changes in urinary bladder epithelial cells." View thesis entry in Australian Digital Theses Program, 2001. http://thesis.anu.edu.au/public/adt-ANU20011207.110344/index.html.

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2

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 OH˙ 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. OH˙ 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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3

Rojko, Christine. "Solar disinfection of drinking water." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0423103-124244.

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4

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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5

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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6

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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7

Cronje, Martin. "Investigation of electrochemical combustion plant for rural water disinfection and industrial organic effluent removal." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16292.

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Thesis (MScIng)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Recent years have seen the development of various treatment methods for the purification of industrial waste waters due to the increased demand for reduced pollutant effluents. Aqueous waste streams containing toxic organic compounds are of special interest, since conventional treatment methods such as biological waste treatment can not always be used. Other popular treatment methods are often ineffective. Catalytic oxidation of organic wastes has been investigated since the 1960s with varying degrees of success. A major problem associated with this method is the high temperatures and pressures required to improve the activation energies involved. Electrochemical oxidation has become a popular method in the literature of treating these wastes, since the applied voltage determines the activation energy, and therefore the process can often be performed at ambient conditions. This thesis investigates the capability of a unique reactor system in the treatment of these wastes. The reactor utilises proton-exchange membrane technology to eliminate the requirement of conductivity in treated waste streams; thus the membrane serves as a solid electrolyte. The reactor system has therefore been referred to as a solid-polymer-electrolyte reactor. Novel metal oxide anodes are responsible for the oxidation of the organic molecules. These metal oxide catalysts show promise in the treatment of a wide variety of organic wastes. A SnO2 catalyst doped with ZrO2 is used as anode in this study. Dopants are added to the catalyst to improve properties such as catalytic activity and conductivity. Kinetic data was obtained on a wide range of values for the chosen experimental parameters (current density and flow rate). Phenol, an organic molecule often referred to in the literature as model contaminant due to its resistance to oxidation,was also used as contaminant in this study. The use of the reactor system in the disinfection of water containing selected pathogens, were included in the experimental work. This kinetic data served in the development of a simple model of the process, and provided the basis for a full analysis regarding potential scale-up and economic feasibility. A requirement of the study was the accurate determination of the various oxidation breakdown products of phenol. This led to the refinement of an HPLC analytical method in order to quantitatively determine these products. The full analysis showed that the current reactor system would not be economically viable — mainly due to very long reactor lengths required for the complete removal of all organic material. Both mass transfer and charge transfer at the chosen experimental conditions influenced the electrochemical oxidation of phenol. High pressure drops, causing low flow rates in the reactor, accounted for this because of the narrow flow channels required in the reactor. Some catalyst deactivation was also suspected to affect the overall reaction, but the full extent of the deactivation was not investigated thoroughly. There is still room for improvement in the electrochemical oxidation of organic wastes. The design of the flow channels, a factor that was not investigated, can significantly improve efficiency. Another aspect that was not investigated was the catalyst type. The catalyst has been identified in the literature as the main contributing factor to the success of the oxidation reaction. A wide variety of metal oxide catalysts are currently being researched and may improve the kinetics of the process even further. Further improvement needs to be made on the membrane/electrode assembly to improve current density distribution. Every improvement of the process in terms of the reactor design and catalyst will impact on the economics of the process, thus making the process more competitive with current treatment technologies.
AFRIKAANSE OPSOMMING: In die afgelope paar dekades, is daar ’n wye verskeidenheid metodes ontwikkel wat gebruik kan word om industri¨ele afvoer strome te behandel. Hierdie ontwikkeling het plaasgevind as gevolg van die verhoogde eis aan skoner afvoerstrome. Wateragtige afvoerstrome wat organiese verbindings bevat, is van besonderse belang omdat hierdie tipe strome soms besonders moeilik kan wees om te behandel. Gebruiklike metodes is in die meeste gevalle ongeskik vir behandelings-doeleindes. Katalitiese oksidasie is sedert die 1960’s gebruik, maar hierdie prosesse benodig dikwels ho¨e drukke en temperature om suksesvol te wees. Elektrochemiese oksidasie het intussen ’n populˆere behandelingsmetode geword, aangesien die aktiveringsenergie vir die oksidasieproses hoofsaaklik afhanklik is van die aangewende potensiaal en dus kan die proses by atmosferiese toestande gebruik word. In hierdie tesis word die geskiktheid van ’n unieke reaktorstelsel vir water-suiwering ondersoek. Die reaktor gebruik ’n proton-uitruilings-membraan om die behoefte vir konduktiwiteit in die water uit te skakel. Die membraan dien dus as ’n tipe soliede elektroliet en as gevolg hiervan word na die reaktorstelsel verwys as ’n soliede-polimeer-elektroliet reaktor. Nuwe metaal-oksied anodes word in die reaktor gebruik aangesien hulle belowende resultate toon in die oksidasie van organiese verbindings. In die navorsing, is ’n SnO2 katalis wat klein hoeveelhede ZrO2 bevat gebruik. Oksiede soos ZrO2 word dikwels gebruik om die aktiwiteit en konduktiwiteit van hierdie kataliste te bevorder. Kinetiese data is oor ’n wye bereik van parameter waardes ingesamel. Die hoof parameters in die eksperimentele werk was stroom digtheid en vloeitempo. Fenol, ‘n komponent wat volgens die literatuur in hierdie tipe van werk gebruik word, isas die besoedelende komponent gekies. Die doeltreffendheid van die reaktor in die ontsmetting van water, wat met ’n verskeidenheid skadelike mikro-organismes besmet is, is ook getoets. ‘n Eenvoudinge model is opgestel m.b.v. die kinetiese data, waarna ’n volledige analise met betrekking tot grootskaalse bedryf en ekonomiese uitvoerbaarheid gedoen is. ‘n Vereiste van die studie was om die konsentrasie van die afbreek-produkte van die oksidasie akkuraat vas te stel. As gevolg hiervan is ‘n ho¨e-druk-vloeistofchromatografie analitiese metode verfyn. Die analise het getoon dat die reaktorstelsel nie ekonomies sou wees nie. Een van die hoofredes hiervoor is die onrealistiese reaktorlengtes wat benodig sou word. Resultate het getoon dat die reaksie deur beide massa-oordrag en lading-oordrag be¨ınvloed word. Ho¨e drukvalle in die reaktor wat gelei het tot lae vloeitempo’s was hiervoor verantwoordelik. Die deaktivering van die katalis be¨ınvloed waarskynlik die reaksie, maar die deaktiveringsverskynsel is nie ten volle ondersoek nie. Die reaktorstelsel kan verder verbeter word deur verskeie elemente van die reaktor te ondersoek. Die ontwerp van die vloeikanale in die reaktor is nie ondersoek nie en kan die werksverrigting van die reaktor verhoog. Uit die literatuur is gevind dat die tipe metaaloksied wat as katalis gebruik word, die reaksie direk be¨ınvloed. Dus kan navorsing wat tans op die kataliste gedoen word nuwe kataliste na vore bring wat meer doeltreffend sal wees. Laastens, is die huidige membraan/elektrode samestelling nog oneffektief en kan die reaktor-opstelling dus nog verbeter word. Elke verbetering wat op die bogenoemde faktore van die reaktor ontwerp verkry word, sal die ekomoniese uitvoerbaarheid van die proses be¨ınvloed. So, sal die proses al meer kompeterend met huidige behandelingsmetodes word.
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8

Har, Yuk-yee Sylvia, and 夏玉兒. "Disinfection in wastewater treatment and its application in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B45013056.

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9

Storlie, Leslee. "An Investigation into Bromate Formation in Ozone Disinfection Systems." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26896.

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Ozonation is used as an alternative disinfection process to chlorination but unfortunately has a potential of oxidizing bromide, a natural component of water sources, to bromate. Bromate is a possible carcinogen with a maximum contaminant level of 10 ppb. To understand bromate formation in full-scale systems, a comprehensive study was conducted at the Moorhead Water Treatment Plant (WTP). Bromide concentrations in source waters were monitored. Water samples from locations in the ozonation chambers were collected and analyzed for bromate and other parameters. Results showed that bromate formation was increased through increases in pH, bromide, and ozone dose during high temperatures and was decreased by increases in organics. The impact of the bromate influential parameters was minimized at low temperatures. To assist Moorhead WTP on developing bromate control strategies, a modeling approach was adopted to predict bromate formation at various operational conditions using temperature, pH, ozone dose, bromide, and TOC.
MWH Global, AWWA Scholarship
American Water Works Association (AWWA), Minnesota and North Dakota sections
North Dakota Water Resources Research Institute
Department of Civil Engineering, North Dakota State University
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10

Gabbai, Udi Edward. "Microbial inactivation using ultraviolet light-emitting diodes for point-of-use water disinfection." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708718.

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11

Malan, Cheryl. "The efficiency of drinking water treatment plants in removing immunotoxins." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5762_1308732795.

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The aim of this study was to evaluate the effectiveness of water treatment processes of two drinking water plants to remove immunotoxins and steroid hormones. Raw and treated drinking water was screened for effects on inflammatory activity using the biomarker IL-6, humoral immunity using the biomarker IL-10 and cell mediated immunity using the biomarker IFN-&gamma
. In vitro human whole blood culture assays were used in order to elucidate potential immunotoxicity.

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12

Heindel, Heather Lee. "A bench-scale examination of the effect of static mixers on the disinfection of cryptosporidium parvum." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20946.

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13

Nguyen, Ha Thi. "Effect of transmittance and suspended soils on the efficacy of UV disinfection of bacterial contaminants in water." Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09AS/09ash111.pdf.

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Errata pasted onto front end-paper. Bibliography: leaves 113-120. To obtain robust and quantitative data on the influence of UV absorption and suspended solids on UV disinfection an experimental study using commercial disinfection technology was undertaken.
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14

Ringer, Erin E. "Reduction of trihalomethanes using ultrasound as a disinfectant." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-050307-084016/.

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15

Wu, L. "The preparation of metal ions modified titanium dioxide and its application in water purification and disinfection." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19578/.

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Conventional water purification and disinfection generally involve potential hazardous substances, some of which known to be carcinogenic in nature. Titanium dioxide photocatalytic processes provide an effective route to destroy hazardous organic contaminants and bacteria, being operational in the UV domain with a potential application in the use of solar radiation. This work explores the possibility of the removal of organic pollutants and microbial contaminant by the application of TiO2 based photocatalysts. The production of series of metal ions doped or undoped TiO2 were carried out by sol gel method and wet impregnation method. Photoreactivity tests were carried out in a solar box with two UVA lamps. The photodegration of phenol and photodisinfection of E. coli in aquatic solution were selected as probe as a measure of photoreactivity. It is found that none of the doped TiO2 show any improvement compared with undoped TiO2 towards phenol degradation. In contrast, Cu doped TiO2 exhibits enhanced results from E. coli photodisinfection. The material properties of prepared photocatalysts were characterized in an attempt to understand the relation among preparation parameters (calcination temperature, the variations of dopant and the level of doping, etc.), material properties and the final photoactvity. The structural characterization includes Brunauer, Emmett and Teller (BET) method, X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). Some field simulation experiments are also included in this research. The results of which proved TiO2 based photocatalytic process to be a promising alternative in the future application in water disinfection and degradation, especially in those tropical developing countries with abundant of solar irradiation and insufficient water sanitation. In the last part of this PhD work, a continuous flow photoreactor was designed. The effectiveness of the system was tested and fitted to mathematical models to describe the bacterial disinfection rate.
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16

Lane, Marshalle. "Dispersive liquid-liquid micro-extraction coupled with gas chromatography for the detection of trihalomethanes in different water sources in the Western Cape, South Africa." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2852.

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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2018.
Trihalomethanes (THMs) are a group of four compounds that are formed, along with other disinfected by-products. This happens when chloride or other disinfectants are used to control microbial contamination in drinking water, which then reacts with natural organic or inorganic substances in water. Trihalomethanes are better known by their common names such as chloroform, bromodichloromethane, chlorodibromomethane and bromoform. These four compounds are known to be classified as cancer group B carcinogens (shown to cause cancer in laboratory animals). Trihalomethane levels tend to increase with pH, temperature, time and the level of “precursors" present. Precursors are known to be organic substances which react with chloride to form THMs. One significant way of reducing the amount of THMs in water is to eliminate or reduce chlorination before filtrations and reduce precursors. There are guideline limits for THMs in the SANS 241:2015 document, but they are not continuously monitored and their levels in natural water are not known. The aim of this study is to develop a rapid, fast and reliable liquid-liquid microextraction technique, to determine the presence of THMs in natural water sources. This study particularly focuses on different water sources e.g. river, underground, borehole and chlorinated water. Chlorinated water is the water that has been presumably treated for bacteria and fungus growth. The results that were obtained for chlorinated water are as follow, 10.120 μg/L − 11.654 μg/L for chloroform, 2.214 μg/L - 2.666 μg/L for bromodichloromethane, 0.819 μg/L − 0.895 μg/L chlorodibromomethane and 0.103 μg/L - 0.135 μg/L for bromoform from validation data. All these THMs concentrations have been found to be below the SANS 241:2015 limits. Natural water shows a very high affinity for chloroform. This is what is expected under normal conditions as chloroform is the most abundant THM of all THMs present in natural water. The liquid-liquid microextraction technique that was optimized and used for the determination of THMs in this study is a rapid, simple and inexpensive technique that provides low limits of detection (LOD) e.g. 0.1999 μg/L chlorodibromomethane and 0.2056 μg/L bromoform and wide dynamic range (LOQ) of 0.6664 μg/L chlorodibromomethane and 0.6854 μg/L bromoform for the determination of THMs.
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17

Olivier, Francois. "Evaluating the potential of ultraviolet irradiation for the disinfection of microbiologically polluted irrigation water." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97970.

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Thesis (MSc Food Sc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Fresh produce irrigation water from Western Cape Rivers carries faecal coliforms (FC) (Escherichia coli) at concentrations which often exceed the suggested limit of 1 000 FC per 100 mL and presents a health risk to consumers. On-farm ultraviolet (UV) irradiation presents several advantages for water disinfection but is an uncommon practice in South Africa. The aim of this study was to investigate the use of UV irradiation for river water disinfection prior to irrigation. Escherichia coli (E. coli) strains were exposed to low-pressure (LP) UV (4 mJ.cm-2) and UV/Hydrogen peroxide (H2O2) (4 mJ.cm-2/20 mg.L-1) treatments in Sterile Saline Solution (SSS). Strain variation in reductions was observed and ranged from 1.58 to 3.68 and 1.34 to 3.60 log for the UV and UV/H2O2 treatments, respectively. The UV/H2O2 treatment (4 mJ.cm-2/20 mg.L-1) was more effective, compared to UV singly, against some of the E. coli strains. Selected strains showed increased sensitivity at higher UV doses (8, 10 and 13 mJ.cm-2) and H2O2 concentrations (100 and 200 mg.L-1 with 4 mJ.cm-2) but a 3 log target reduction was not always reached. For all UV and UV/H2O2 treatments maximum resistance was shown by an environmental strain. Reference strains should, therefore, not be used for the optimisation of UV based disinfection parameters. At 10 mJ.cm-2 an American Type Culture Collection (ATCC) reference strain and an environmental strain (ATCC 25922 and F11.2) were both significantly less inactivated in sterilised river water compared to SSS. Enhanced water quality allowed for improved inactivation of the ATCC strain. Also, the efficiency of LP UV (5, 7 and 10 mJ.cm-2) and medium-pressure (MP) UV (13, 17 and 24 mJ.cm-2) radiation was investigated using water from the Plankenburg River. Water was sampled and treated on three respective days (Trials 1 to 3). Physico-chemical and microbiological water quality was always poor. The FC concentration reached a maximum of 6.41 log cfu.100 mL-1 while UV transmission was always below 38%. For LP and MP UV irradiation increased doses resulted in increased disinfection but a 3 log reduction of FC was only attained when MP UV light was used in Trial 1. Disinfection efficiency was dependent on water quality and on the characteristics of the microbial population in the water. Since FC were never reduced to below 3 log cfu.100 mL-1, the water did not adhere to guidelines for produce irrigation. Photo-repair following irradiation was investigated in river water using MP UV doses of 13 and 24 mJ.cm-2 and 3.5 kLux reactivating light, initially. Ultraviolet transmission was close to 50% and total coliform (TC) reduction exceeded 3 log, even at 13 mJ.cm-2. However, TC were reactivated from below 1 000 cfu.100.mL-1 to 3.93 and 4.41 log cfu.100 mL-1 for the 13 and 24 mJ.cm-2 treatments, respectively. A higher MP dose (40 mJ.cm-2) and a different treatment regime (2 x 20 mJ.cm-2) inhibited photo-repair (compared to 13 and 24 mJ.cm-2) but TC were always recovered to a final concentration surpassing 3 log cfu.100 mL-1, even under lower light intensities (1.0 to 2.0 kLux). In the current study UV irradiation did not produce water of acceptable standards for produce irrigation, mainly as a result of extremely poor water quality. However, on farm-scale, UV efficiency could be enhanced by improving water quality before irradiation. Also, stronger lamps that deliver higher UV doses may result in adequate disinfection, irrespective of water quality. Higher UV doses and the use of combination treatments (such as UV/Chlorine and UV/Peracetic acid) should be further investigated also to determine its disinfection efficiency and possible capability to inhibit post-disinfection repair.
AFRIKAANSE OPSOMMING: Varsproduk besproeiingswater vanuit Wes-Kaapse riviere bevat fekale kolivorme (FK) (Escherichia coli) in konsentrasies wat dikwels die voorgestelde limiet van 1 000 FK per 100 mL oorskry en hou `n gesondheidsrisiko vir verbruikers in. Plaasvlak ultraviolet (UV) bestraling bied verskeie voordele met verwysing na water dekontaminering, maar word selde aangewend in Suid-Afrika. Die doel van hierdie studie was om die gebruik van UV bestraling vir die dekontaminering van rivierwater, voor besproeiing, te ondersoek. Escherichia coli (E. coli) isolate is blootgestel aan lae-druk (LD) UV (4 mJ.cm-2) en UV/Waterstofperoksied (H2O2) (4 mJ.cm-2/20 mg.L-1) behandelings in Steriele Sout Oplossing (SSO). Isolaat variasie in reduksies is waargeneem en het gewissel tussen 1.58 tot 3.68 en 1.34 tot 3.60 log vir die UV en UV/H2O2 behandelings, onderskeidelik. In vergelyking met UV bestraling alleen was die UV/H2O2 behandeling (4 mJ.cm-2/20 mg.L-1) meer effektief teen sommige E. coli isolate. Geselekteerde isolate was meer sensitief tot hoër UV dosisse (8, 10 en 13 mJ.cm-2) en H2O2 konsentrasies (100 en 200 mg.L-1 met 4 mJ.cm-2), maar `n 3 log teikenreduksie was nie altyd haalbaar nie. Vir alle UV en UV/H2O2 behandlinge was die meeste weerstand deur `n omgewingsisolaat gebied. Verwysingsisolate behoort daarom nie aangewend te word vir die optimisering van UV-gebaseerde behandelingsparameters nie. By 10 mJ.cm-2 was beide `n ATCC verwysingsisolaat en `n omgewingsisolaat (ATCC 25922 en F11.2) betekenisvol minder gedeaktiveer in rivierwater as in SSO. Verbeterde waterkwaliteit het verhoogde inaktivering van die ATCC isolaat toegelaat. Die doeltreffendheid van LD UV (5, 7 en 10 mJ.cm-2) en medium-druk (MD) UV (13, 17 en 24 mJ.cm-2) bestraling is ook ondersoek deur watermonsters vanuit die Plankenburg Rivier te gebruik. Watermonsters was getrek en behandel op drie verskillende dae (Proewe 1 tot 3). Fisies-chemiese en mikrobiologiese kwaliteit van die water was deurentyd swak. Die FK konsentrasie het `n maksimum van 6.41 log kve.100 mL-1 bereik terwyl UV transmissie altyd laer as 38% was. Vir beide LD en MD UV bestraling het verhoogde dosisse gelei tot verbeterde dekontaminering, maar `n 3 log reduksie is slegs bereik toe MD UV lig gebruik is in Proef 1. Die effektiwiteit van die behandelings was afhanklik van waterkwaliteit en die eienskappe van die mikrobiese populasie in die water. Aangesien FK nooit tot onder 3 log kve.100 mL-1 verminder is nie het die water nie voldoen aan riglyne vir varsproduk-besproeiing nie. Fotoherstel na bestraling was ondersoek in rivierwater deur aanvanklik gebruik te maak van MD UV dosisse van 13 en 24 mJ.cm-2 en 3.5 kLux heraktiverende lig. Ultraviolettransmissie het byna 50% bereik en reduksie van totale kolivorme (TK) het 3 log oorskry, selfs by 13 mJ.cm-2. Totale kolivorme was egter geheraktiveer van onder 1 000 kve.100.mL-1 tot 3.93 en 4.41 log kve.100 mL-1 vir die 13 en 24 mJ.cm-2 behandelings, onderskeidelik. In vergelyking met 13 en 24 mJ.cm-2 het `n hoër MD dosis (40 mJ.cm-2) en `n veranderde bestralingstegniek (2 x 20 mJ.cm-2) fotoherstel onderdruk, maar TK was in elke geval geheraktiveer tot `n finale konsentrasie hoër as 3 log kve.100 mL-1, selfs onder laer intensiteit lig (1.0 tot 2.0 kLux). In hierdie ondersoek het UV bestraling nie water van aanvaarbare standaarde vir varsproduk besproeiing gelewer nie, hoofsaaklik as gevolg van swak waterkwaliteit. Nietemin, op plaasvlak mag die effektiwiteit van UV bestraling verhoog word deur waterkwaliteit voor bestraling te verbeter. Die gebruik van sterker lampe, om hoër UV dosisse te produseer, mag verder bydra tot voldoende dekontaminasie, ongeag van waterkwaliteit. Hoër UV dosisse en die gebruik van kombinasie behandelinge (soos UV/Chloor en UV/Perasynsuur) moet ook verder ondersoek word om die dekontaminasie effektiwiteit, en vermoë daarvan om heraktivering na dekontaminering te onderdruk, vas te stel.
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18

Kim, Dongjin. "Large eddy simulation of flow in water and wastewater disinfection reactors." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41089.

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Hydrodynamic behavior in reactors used for water treatment, particularly in ozone contactors with serpentine flow, is known to strongly affect the process efficiency. However, exact flow characteristics inside these reactors are not well understood, as traditional approach either considers these reactors as black box or relies on less accurate Reynolds-Averaged Navier-Stokes (RANS) simulation. In order to provide a deep understanding of the hydrodynamics and solute transport phenomena in these reactors, high resolution numerical studies using the Large Eddy Simulation (LES) method are performed. The reactor geometries investigated in this research are Constant Baffle Spacing Multi-Chamber (CBSMC) ozone contactors and a Variable Baffle Spacing ozone contactor Model (VBSM). The LES results in two multi-chamber ozone contactors (CBSMC -Normal-Width and -Half-Width) suggest that the flow through these reactors is characterized by the presence of extensive short-circuiting and large internal recirculation. The results also suggest that the flow is highly three dimensional with a pair of symmetric counter-rotating secondary vortices. LES studies based on VBSM, the baffle spacing of which varies between 0.5 times to 5 times the size of the base chamber; suggest that the width of the recirculation zone grows at about the same rate as the baffle spacing. Instantaneous turbulent eddies are prevalent in the chamber and increase turbulent mixing. The elevated levels of turbulence are found in the short-circuiting flow path. The tracer is dispersed along the short-circuiting path and strongly into the recirculation zone due to turbulent diffusion. Baffle spacing greater than the entrance gate height, but also smaller baffle spacing, worsens the disinfection efficiency. Finally, the turbulent Schmidt number of RANS simulation was investigated by employing the previously validated LES simulation. Due to the presence of very strong turbulent diffusion in the reactors, the turbulent Schmidt number is found out to be much less than the values commonly used, and is also specific to the baffle spacing.
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Gandhi, Varun N. "Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45895.

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The validation of UV reactors is currently accomplished by biodosimetry, in which the reactor is treated as a "black-box" and hence cannot account for the dependence of the dose delivery on the complex hydrodynamics and the spatial variation in UV intensity. Alternative methods, such as fluorescent microspheres as non-biological surrogates and computational fluid dynamics (CFD) simulations, have been developed; however, each method has its shortcomings. In this study, a novel technique for the spatial and temporal assessment of the hydrodynamics and the UV dose delivered and the link between these two factors in a lab-scale UV reactor using three dimensional laser induced fluorescence (3DLIF) is developed. This tool can also be utilized for the optimization of UV reactors and to provide data for validation of CFD-based simulation techniques. Regions of optimization include areas around the UV lamp where short-circuiting occurred, a longer inlet approach section that enhances the performance of the reactor by reducing short circuiting paths and a longer outlet region to provide greater mixing. 3DLIF allows real time characterization of mixing and dose delivery in a single lamp UV reactor placed perpendicular to flow by capturing fluorescence images emitted from a laser dye, Rhodamine 6G, using a high speed CCD camera. In addition to three-dimensional mixing, the technique successfully visualized the two-dimensional, transient mixing behaviors such as the recirculation zone and the von Karman vortices and the fluence delivery within the reactor, which has not been possible with traditional tracer test techniques. Finally, a decomposition technique was applied to the flow and fluence delivery based concentration data to reveal similar structures that affect these phenomena. Based on this analysis, changing the flow in the reactor, i.e. the Reynolds number, will directly affect the fluence delivery.
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Baek, Nak-hyun. "The impact of a change in disinfectants on the water quality of a distribution system." Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/902475.

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Chloramine is a widely used alternative disinfectant for chlorine in potable distribution water. This alternative was investigated and employed to show its effect for suppressing coliforms, trihalomethanes(THMs), disinfection by-products (DBPs), and corrosivity.Coliform analyses were performed with m-Endo(total coliform) and m-T7 agar(injured coliform) by using a standard Membrane Filtration method. Heterotrophic bacteria were monitored with HPC agar(PCA) and R2A agar (nutrient limited agar). EPA methods 502.2, 524.2, and 504 were used to determine levels of Trihalomethanes(THMs) and Disinfection by-products(DBPs).In our study, we observed no significant differences in coliform counts, that could be attributed to the switch in disinfectant. The most common coliform identified was Enterobacter cloacae. We also noted that m-T7 performed better than m-Endo in the detection of coliforms. We also observed a low level of corrosion (0.4-3.8 mils/year) in the distribution system (DS). Higher counts of heterotrophic bacteria were enumerated on R2A when compared to HPC. DBP values decreased two fold when compared with DBP values for the two previous years during which chlorine was used as the disinfectant.
Department of Biology
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THURMAN, ROBERT BRUCE. "THE CHARACTERIZATION OF VIRUS INTERACTION WITH SELECTED SURFACE CONTACT DISINFECTANTS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184104.

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The search for alternative water disinfectants to those commonly used, such as chlorine, probably began when the disadvantages of those disinfectants became known. Soluble disinfectants have short half-lives and need to be replenished periodically which requires monitoring the determination of appropriate concentrations for waters being treated. This disadvantage may be balanced by the ability to alter dose concentrations of soluble disinfectants to meet changes in demands. Maintenance of a residual disinfectant concentration which can act throughout a water distribution system is another advantage of soluble disinfectants. Disadvantages due to reaction of organic materials include the loss of disinfecting capability, health hazards related to the disinfectant and the potential loss of aesthetic water qualities such as taste, smell and color. The purpose of this study was to investigate different surface contact disinfectants which, while having an inflexible dose concentration capability and releasing no residual disinfectant concentration, do not require monitoring and do not significantly leach into the waters they contact. Powdered aluminum when mixed with a loamy sand reduces virus concentration 3-4 orders of magnitude better than controls while not significantly altering the pH or aluminum concentration of waters that pass through the soil columns. Labeled poliovirus 1 was found to adsorb onto the aluminum surface in batch experiments and undergo degradation or dissociation of the capsid proteins with release of viral fragments and clumps within 76 hours. Freon dispersion of the viral clumps showed the clumps to be non-infective. Polyacrylamide gel electrophoresis of poliovirus 1 incubated with aluminum for 76 hours suggested degradation or dissociation of viral capsid proteins 1, 2 and 3. Magnesium peroxide and magnesium oxide, while effectively inactivating viruses, significantly increase the pH of water which they contact. Polyhalex resin and I5 resin reduce virus concentration, but release functional groups into the surrrounding water. Contact disinfectants such as aluminum, may find point-of-use application for drinking water, use in septic tank leachfields or sewage treatment infiltration basins to reduce the threat of spreading potential disease-causing organisms.
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22

Park, Sang Hyuck. "Effect of amine-based water treatment polymers on the formation of N-nitrosodimethylamine (NDMA) disinfection by-product." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22549.

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In recent years, a compound N-nitrosodimethylamine (NDMA), a probable human carcinogen, has been identified as an emerging disinfection by-product (DBP) since its formation and detection were linked to chlorine-based disinfection processes in several water utilities in the U.S. and Canada. Numerous organic nitrogen compounds present in water may impact the formation of NDMA during disinfection. Amine-based water treatment polymers used as coagulants and flocculants have been suggested as potential NDMA precursors due to the presence of amine functional groups in their structures, as well as the possible presence of dimethylamine (DMA) residues in polymer products. To minimize the potential risk of NDMA associated with water treatment polymers, the mechanisms of how the polymers behave as NDMA precursors and their contribution to the overall NDMA formation under actual water treatment conditions need to be elucidated. This research involved a systematic investigation to determine whether amine-based water treatment polymers contribute to NDMA formation under drinking water and wastewater treatment conditions, to probe the involved reaction mechanisms, and to develop strategies to minimize the polymers NDMA formation potential. The investigation included five research tasks: (1) General screening of NDMA formation potential of commonly used amine-based water treatment polymers, (2) NDMA formation from amine-based water treatment polymers under relevant water treatment conditions, (3) Probing the mechanisms of NDMA formation from polyamine and PolyDADMAC, (4) Effect of water treatment processes on NDMA formation from amine-based water treatment polymers, and (5) Developing strategies to reduce polymers NDMA formation potential. Direct chloramination or chlorination of high doses of polymers in deionized water at longer than typical contact time was used in the general screening of the NDMA formation potential of water treatment polymers and in the studies to identify reaction mechanisms. On the other hand, realistic dosages of chloramines and polymers and contact time were used in simulating representative water treatment conditions to evaluate the contribution of polymers to the overall NDMA formation in real systems. On the basis of the study results, strategies were developed to reduce the NDMA formation potential of amine-based water treatment polymers, which include modification of polymer structures and treatment parameters.
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Lui, Yuen Shan. "Formation of disinfection by-products and mutagenicity upon chlorination of algal-derived organic materials." HKBU Institutional Repository, 2010. http://repository.hkbu.edu.hk/etd_ra/1181.

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24

Akande, Babatunde Cornelius. "Disinfection by-products and their biological influence on radicle development, biomass accumulation, nutrient concentration, oxidative response and lipid composition of two tomato (Solanum lycopersicum) cultivars." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2336.

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Thesis (DTech (Environmental Health))--Cape Peninsula University of Technology, 2016.
Trihalomethanes are disinfection byproducts of chlorinated waters, and there is a growing interest to understand plant responses to organohalogens. This study investigates the effects of increasing trihalomethane dose on the physiology of tomato (Solanum lycopersicum) and determines whether the extent of physiological impacts of trihalomethane exposure on seedling radicle length, biomass accumulation, concentration levels of 12 key nutrients, oxidative stress, fatty acids and α-tocopherol content in membrane lipids of tomato correlated with either the number of bromine or chlorine atoms in the trihalomethane molecules. The 2 x 4 x 5 factorial experiment was laid out in CRD with four replications. Two cultivars of tomato were exposed to 4 levels of trihalomethanes (bromodichloromethane, bromoform, chloroform and dibromochloromethane) and 5 levels of concentration (0.0, 2.5, 5.0, 7.5, and 10.0 mg.L-1) in a green house. The decrease in seedling biomass and the inhibition of radicle growth increased with increasing trihalomethane concentrations in a dose dependent manner. Also, both these parameters decreased in response to an increase in the number of bromine atoms in the trihalomethane molecule. However, in growing plants the decrease in concentration levels of seven essential nutrients namely nitrogen (N), phosphorus (P), potassium (K), sulphur (S), copper (Cu), zinc (Zn) & boron (B) correlated to an increase in the number of chlorine atoms. Increase in trihalomethane dose also induced a decrease in all the above mentioned nutrients with the addition of manganese (Mn), although the decrease in P and S were not significant at P ≤ 0.05. The increase in trihalomethane dose induced an increase in oxidative stress parameters such as the total phenolic content, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and lipid peroxidation. The increase in the above parameters correlated to an increase in the number of chlorine atoms, however, no such correlations were observed in superoxide dismutase (SOD) activity, general lipid peroxidation, α-tocopherol content and totalsoluble proteins. In plant membrane lipids, increase in the saturated fat hexadecanoic acid was observed in both tomato cultivars that correlated to the degree of chlorination in the trihalomethane molecule. The increase in α-linolenic acid stress signaling correlated with an increase in the degree of chlorination in only one tomato cultivar suggesting variable tolerance between cultivars to chemical action. Membrane lipids adjustments in tomato plants exposed to increasing trihalomethane dose were based on two factors; first the adjustments of membrane fluidity with the increase in plant sterols and fatty acids content and secondly, the increase in lipophyllic antioxidants such as phenols, quinones and α-tocopherol content. The phenolic lipophyllic antioxidant was tentatively identified to be 2,2’-methylenebis [6-(1,1-dimethylethyl)-4-methyl] phenol. In conclusion, the magnitude of plant responses to trihalomethanes is more dependent on the halogenation number of the molecule and less on its concentration.
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25

Farren, Elizabeth Anne. "Reducing trihalomethane concentrations by using chloramines as a disinfectant." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0429103-095058.

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26

McAuley, Kimberley. "Disinfection by-products and public health concerns." University of Western Australia. School of Population Health, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0070.

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Disinfection by-products (DBPs) are a major group of water contaminants and their role in causing adverse health outcomes, including adverse pregnancy outcomes, endocrine disruption, respiratory related adverse health outcomes and cancer has been subject to extensive epidemiological and toxicological research and review. Determination of safe exposure to DBPs, particularly within drinking water supplies, has been a topic of extensive debate, with a wide range of acceptable levels set across the industrialized world. The focus of the research in this thesis was on two of the main health outcomes associated with DBP exposure, namely adverse pregnancy outcomes and asthma related symptoms. To assess adverse pregnancy outcomes in Perth, an extensive classification quantification of the major DBPs in Perth drinking water was conducted. A registrybased prevalence study was carried out to assess birth defects in relation to high, medium and low DBP areas (defined by the water sampling and analysis). It was found that women living in high THM areas are 22% (odds ratio (OR) 1.22, 95% confidence interval (95% CI) 1.01-1.48) more likely of having a baby with any birth defect. High exposure was also strongly associated with an increased risk of having a baby with a cardiovascular defect (62% increased risk). Low birth weight and prematurity were also assessed; however these outcomes were not associated with an increased risk through an increase in exposure. Following on from this analysis, a population risk assessment model was developed for DBPs in high exposure environments. This involved a three step process: (i) Firstly a questionnaire-based validation and reliability study was used to assess water consumption patterns of a population of pregnant women in Perth. (ii) Secondly a prediction model for teratogenic burden of DBPs in Perth was developed, related to the exposure patterns of the population of pregnant women involved in the validation and reliability study. (iii) Finally, combining the information collected in (i) and (ii), along with the regression slope estimates for birth weight from the prevalence study (defined in Section 2.2.1), a dose-response model for THMs and birth weight was developed. Predictive simulations for birth weights at given THM levels were then conducted. It was estimated that pregnant women in Perth are exposed to between 0.3 – 4.10 µg/day ingested TTHM, and of this, the more toxic brominated forms accounted for between 0.27 – 3.69 µg/day. Based on a dose-response model used, birthweights calculated for the ‘hypothetical’ exposures ranged from 3403.2g for the highest exposure to 3503.5g in the lowest exposure, which is a difference of over 100g. Although the resulting reduction in birth weight is not extreme, there is still a significant reduction in birth weight present as exposure to TTHMs increases. This is the first doseresponse model to be developed to assess an adverse pregnancy outcome based on pregnant women exposure data, and will be a useful tool for assessing varying exposures throughout not only Australia but also throughout the industrialised world, where DBP exposure is highly prevalent.
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Hong, Huachang. "Characteristics of natural organic matter in Hong Kong's source drinking water and its association with the formation of disinfection by-products." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/894.

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28

Kadry, Ahmed Y. "Removal of selected water disinfection byproducts, and MTBE in batch and continuous flow systems using alternative sorbents." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3285/.

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A study was conducted to evaluate the sorption characteristics of six disinfection byproducts (DBPs) on four sorbents. To investigate sorption of volatile organic compounds (VOCs), specially designed experimental batch and continuous flow modules were developed. The investigated compounds included: chloroform, 1,2-dichloroethane (DCE), trichloroethylene (TCE), bromodichloromethane (BDCM), methyl tertiary butyl ether (MTBE), bromate and bromide ions. Sorbents used included light weight aggregate (LWA), an inorganic porous material with unique surface characteristics, Amberlite® XAD-16, a weakly basic anion exchange resin, Amberjet®, a strongly basic anion exchange resin, and granular activated carbon (GAC). Batch experiments were conducted on spiked Milli-Q® and lake water matrices. Results indicate considerable sorption of TCE (68.9%), slight sorption of bromate ions (19%) and no appreciable sorption for the other test compounds on LWA. The sorption of TCE increased to 75.3% in experiments utilizing smaller LWA particle size. LWA could be a viable medium for removal of TCE from contaminated surface or groundwater sites. Amberlite® was found unsuitable for use due to its physical characteristics, and its inability to efficiently remove any of the test compounds. Amberjet® showed an excellent ability to remove the inorganic anions (>99%), and BDCM (96.9%) from aqueous solutions but with considerable elevation of pH. Continuous flow experiments evaluated GAC and Amberjet® with spiked Milli-Q® and tap water matrices. The tested organic compounds were sorbed in the order of their hydrophobicity. Slight elevation of pH was observed during continuous flow experiments, making Amberjet® a viable option for removal of BDCM, bromate and bromide ions from water. The continuous flow experiments showed that GAC is an excellent medium for removal of the tested VOCs and bromate ion. Each of the test compounds showed different breakthrough and saturation points. The unique design of the continuous flow apparatus used in the study proved to be highly beneficial to assess removal of volatile organic compounds from aqueous solutions.
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Adeleye, Adeola Patience. "Perfluorinated compounds, bishenol a and acetaminophen in selected waste water treatment plants in and around Cape Town, South Africa." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2331.

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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016.
The release of wastewater to the aquatic environment is most likely to introduce some trace levels of organic contaminants, some of which may be toxic, carcinogenic, or endocrine disruptors, as well as, persistent in the environment. Additionally, increasing contamination of surface waters by wastewater effluents has made water treatment processes more challenging and expensive. The presence of these pollutants in the receiving water body may have negative effects on aquatic species and often pose potential human health risks through the reuse of treated wastewater for drinking purposes and other household use. In countries like South Africa, Namibia, USA, Singapore and Australia, water agencies are intensifying wastewater reclamation/wastewater reuse as part of their water resource agenda: in order to meet the demands of the growing populations. Nowadays, water reuse is generally considered as a viable method of water supply management. This study focused on the identification of the occurrence, quantification of emerging contaminants and evaluation of removal efficiency in wastewater treatment processes of three classes of emerging contaminants (ECs) in wastewater: 1) six types of perfluorinated compounds (PFCs), namely; perfluorooctanoic acid (PFOA), Perfluorooctane sulphonate (PFOS), perfluoroheptanoic acid (PFHpA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUDA); 2) bisphenol A (BPA); and 3) Acetaminophen (ACP). These contaminants were identified and quantified in four wastewater treatment plants in the Western Cape. These treatment plants include three WWTPs in Cape Town, namely: Bellville WWTP, Scottsdene WWTP and Zandvliet WWTP and one WWTP in the central Karoo (Beaufort West wastewater reclamation plant).
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Andersson, Nina. "Analys av dricksvattenrening med metoderna Mikrobiologisk riskanalys (MRA) och God desinfeksjonspraksis (GDP)." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63084.

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Drinking water is produced from raw water and is either from groundwater or surface water. This thesis aims to find out if the cleaning process of raw water is sufficiently effective. This is important because consumers are otherwise at risk of waterborne infection caused by pathogens. There are three groups of pathogens; bacteria, virus and parasite. These have different characteristics which mean that they require different water treatment to be separated. In addition to normal operation, a number of scenarios were examined. This is to investigate how water treatment would do if they became a reality. The thesis has examined Borg´s waterworks operated by Norrköping Vatten AB. It was defined to cover the distance from water source to the consumer. In the work, the model Quantitative Microbial Risk Assessment (QMRA) was used to perform risk analysis by simulating the normal operation and different scenarios of the water purification process. Thus, knowledge can be obtained about the effectiveness of separation by bacteria, viruses and parasites. However, the QMRA-model is considered to contain some flaws and for that reason the Norwegian model called Good Disinfection Practice (GDP) was also used. GDP is a theoretical model which is based on formulas and tables. The model takes into account the raw water quality and also provides deductions for various measures that the water plant possesses to ensure a good supply of water. The results obtained with both models were similar and showed that the water treatment is sufficient for the bacteria, but not viruses and parasites. Both models were considered to be reliable but viruses and parasites are very difficult to analyze, which has resulted in uncertain literature values and hence in the results. The result also showed that neither viruses nor parasites exceeded the limit by so much that more hygienic barriers to the reduction of them are necessary. The conclusion which may be drawn from the fact that no parasites have been detected in the raw water is that the water treatment still might be sufficient. To determine the effects that an exclusion of various barriers may give, the normal operation was simulated and a purification step at a time was excluded. The result showed that the purification steps which are most important to maintain the treatment process are chemical precipitation followed by rapid filtration, slow filtration and disinfection with chlorine. If any of these cleaning steps were to fail, this introduces a large increase in the risk of waterborne disease. The results showed that the chemical precipitation step gave the greatest separation effect on the virus but also on the parasites. However, the slow filtration gave the largest separation of the parasites. Free chlorine had the greatest effect on bacteria. The investigated scenarios were assumed to be wastewater discharges, sewage discharges in relation to flood the nearby pastures, and sewage overflows due to heavy rainfall. The results of the simulated scenarios were the same when it was only bacteria that in all cases produced a result within the limits of the daily infection probability. Both viruses and parasites exceeded both values. However, there were few studies on these and thus literature values needed to be implemented in the QMRA-model. Hence, the uncertainty of the results was great. The QMRA-model also contained deficiencies in the simulation of the discharge of effluents, where the amount of virus was about 1000-10000 times too much. If this problem as well as more specific data for the investigated area, and more Swedish studies were available, a more credible simulation of the scenarios could be implemented.
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Littlejohn, Carla Louise, and n/a. "Influence of Artificial Destratification on Limnological Processes in Lake Samsonvale (North Pine Dam), Queensland, Australia." Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050211.133123.

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Artificial destratification equipment was installed in Lake Samsonvale in October 1995 to reduce the biomass of potentially toxic cyanobacteria in the reservoir. This study was undertaken to investigate the effects of the destratifier on the limnological processes occurring in the lake and to determine if operation of the destratifier has been effective at reducing the summer populations of Cylindrospermopsis raciborskii and Microcystis aeruginosa. The study showed that artificial destratification of Lake Samsonvale has been successful at reducing the surface to bottom thermal gradient and increasing dissolved oxygen concentrations at depth. While the destratifier has not resulted in the lake becoming completely 'mixed' during summer, it has weakened resistance to mixing from meteorological events, which has led to a reduction in mean concentrations of total and dissolved phosphorus during summer. Although not conclusive, it is likely that the influence of the destratifier is restricted to a narrow radial distance around the bubbleplumes during periods of strong stability, so internal loading may continue to provide a substantial source of nutrients for cyanobacterial growth, particularly in regions of the lake less influenced by the destratifier. The results for cyanobacteria are less encouraging. Despite the reduction in concentrations of dissolved phosphorus, the destratifier has not been effective at reducing summer populations of C. raciborskii and M. aeruginosa. On the contrary, there is evidence to suggest that populations have actually increased which could have serious operational consequences for the lake by mixing the previously buoyant cyanobacteria to the level of the water off-take. The growth season for C. raciborskii has been extended by up to 3 months and population onset now occurs during spring. This increase in spring populations could be a result of significantly greater baseline populations during winter, or the earlier germination of akinetes as a result of increased sediment temperatures. The seasonal successional relationship between C. raciborskii and M. aeruginosa appears to have shifted from one of alternating dominance between the two species to one of co-existence under conditions of intermediate disturbance. It was concluded that although the continued operation of the destratifier may prove useful to minimise water treatment costs through reducing internal loading of dissolved constituents, it has not been successful in achieving its original objective of controlling cyanobacterial populations in the lake.
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Thompson, Scott A. "Managing the acidity of abandoned water filled coal mining voids in Collie (Western Australia) using organic matter." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2000. https://ro.ecu.edu.au/theses/1352.

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The effectiveness of using organic matter additions to increase pH in abandoned water filled coal mining voids in Collie was investigated. Previous studies have demonstrated that passing acidic drainage through organic matter increased the waters pH. Laboratory trials using intact sediment cores (collected from Ewington, Collie, Western Australia) were used to assess the effects of additions of hay, manure and mulched vegetation on pH, nutrients an sulphate levels. In a series of experiments the effect of different quantities of organic material, sulphate reducing bacterial inoculations and alkalinity generation were measured. A subsequent field experiment was conducted to examine the impact that manure and mulch had on mine void water in 18 in situ ponds constructed adjacent to Ewington. It was concluded from the laboratory experiments that mulch and manure treatments were significantly better than hay as an organic matter addition for increasing the pH of acidified mine void water at Ewington. The manure produced the greatest increase in pH, although it contributed less to alkalinity than mulch; suggesting mulch bas a greater ability to release carbonates than did manure. The manure and mulch additions increased the pH in the laboratory and field experiment by 0.5-1.5 pH units. This increase was sustained for most of the 21 week field experiment. An increase in pH in the control ponds was recorded over the last 8 weeks of the experiment which was probably due to the inflow of more alkaline groundwater through the substratum as a consequence of the winter rainfall. pH values measured in the experimental ponds 15 months after the commencement of the project indicated that the ponds treated with manure maintained significantly higher pH levels than either the mulch or the control ponds. There was no difference between the pH values for the ponds treated with mulch and the controls suggesting that manure not only provided a greater increase in pH but also over a longer period. The addition of organic mailer also resulted in an increase in gilvin in the laboratory experiments. Low sulphate and sulphide levels were also recorded in all experiments before and after the introduction of organic materials into mine void water and ponds adjacent to Ewington indicating that sulphate reducing bacterial activity was not the cause for the increase in pH as occurred in other situations, but rather the addition of alkaline organic matter caused the increase in pH. The addition of manure organic material was associated with an increase in the ortho-phosphate levels, resulting in an increase in chlorophyll a concentrations. It is believed to be the first stages of succession processes leading to the establishment of a biologically active wetland system. During this process the emerging ecosystem neutralises the acidic content of the water.
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33

Söderlund, Sundling Robin. "Övervakning av desinfektionseffekt i vattenrenare för dialys." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-163249.

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Dialys är en medicinteknisk teknik som används för att rena blod vid nedsatt njurfunktion. Dialysvätska är en viktig komponent i utrustningen. Syftet med examensarbetet var att utvärdera förbättrade rutiner för kvalitetskontroll av vattnet som används för tillredning av dialysvätskan. Ett program för övervakning av desinfektionseffekt i vattenrenare för dialys har utvecklats i Microsoft Visual Studio, med Windows Forms som plattform och kod skriven i C#. Mjukvaran övervakar konduktivitet, dagar sedan desinfektion, desinfektionseffekt (A₀), aktivitet hos loggningsprogram samt kontrollprogram. Larm skickas via mail vid dåliga värden eller fel, samt visas lokalt på dator i form av en textruta. Ett ytterligare program skapades för att kontrollera att huvudprogrammet är igång, och en varning skickas när aktivitet uteblir under en viss längd. Utöver övervakning skapades även en grafisk del som tillåter visning av loggade data samt beräknade A₀-värden över tid. Analys utförs kring möjligheter att bibehålla mikrobiologisk trend med stabilt låg bakterienivå i vattnet vid minskad desinfektionsfrekvens från tre till två gånger i veckan. Provtagningar tyder på att marginal till gränsvärde inte hotas, men mer data behövs för at bekräfta resultatet. Analys utförs även kring möjligheten att använda beräkning av A₀-värden för att verifiera desinfektionseffekt tidigare än resultat från mikrobiologisk provtagning, vilket resultat från den studie som utförts tyder på är möjligt, med vissa undantag där det inte finns data att förhålla sig till. Vid användning av mjukvaran rekommenderas fortsatta mikrobiologiska provtagningar.
Dialysis is a health technology used for cleaning blood in people with kidney failure. Dialysis fluid is an important component used in the dialysis process. The aim of the project is to evaluate improved quality control routines for the water used in preparation of the dialysis fluid. A program for monitoring disinfection effect in water purification systems for dialysis has been developed in Microsoft Visual Studio, using Windows Forms as platform and the code was written in C#. The software monitors conductivity, days since last disinfection, effect of disinfection (A₀), activity of logging software as well as control software. Warnings are sent by mail for bad results or errors, and a message is shown as a textbox locally on the computer running the software. An additional program was made for monitoring the main programs activity, and a warning is sent after seeing no activity within a time period. Other than monitoring, the software also has a graphical view allowing the user to view logged data and calculated A₀-values over time. An analysis is made regarding the possibility to maintain microbiological trend of low amounts of bacteria in water after reducing the disinfection frequency from three to two times a week. Test results indicate that the margin to the maximum allowed value remains on safe levels, but more data is required to confirm the results. A further analysis is made regarding the possibility to use calculations of A₀-values to verify the disinfection effect earlier than results from microbiological testing. Results from studies indicate that this is possible, but with some exceptions in cases where not enough data is available to draw conclusions. When using the software, continued microbiological testing is recommended.
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34

Cervero, Aragó Sílvia. "Eficàcia deIs desinfectants de I'aigua sobre Legionel·la spp. i les seves amebes hostes = Efficiency of water disinfectants against Legionella spp. and their amoeba hosts." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/128960.

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Abstract:
Les infeccions causades per Legionella són un greu problema de salut pública al nostre país. La majoria de casos esporàdics i de brots epidèmics es relacionen amb aigües de consum que han estat sotmeses a un o més processos de desinfecció. Tot i això, Legionella spp. no només és capaç de sobreviure a aquests tractaments sinó que es multiplica al llarg dels sistemes de distribució convertint-se en un risc ambiental. Els principals factors que afavoreixen la supervivència i multiplicació de Legionella als sistemes d’aigua resideixen en la pròpia biologia del bacteri, que ha demostrat en moltes ocasions ser resistent a condicions físico-químiques extremes, així com les interrelacions que estableix amb altres microorganismes com els protozous, amb els que comparteix hàbitat. Els protozous, i en concret les amebes de vida lliure dels gèneres Acanthamoeba o Hartmannella s’han descrit en els últims anys com habitants freqüents dels sistemes de distribució d’aigua. Aquestes sobreviuen a condicions adverses mitjançant la formació d’estructures de resistència anomenades cists. La font nutricional de les amebes són els bacteris els qual fagocita i digereix. Tot i això, alguns d’aquests bacteris han desenvolupat estratègies per sobreviure la digestió amebiana i no sols això sinó que com en el cas de Legionella, poden fins i tot aprofitar els resursos cèl•lula hoste per multiplicar-se. A més, en estat endosimbiont Legionella queda protegida de l’efecte de desinfectants fet que podria originar una ràpida recolonització dels sistemes d’aigua un cop acabats els tractaments de desinfecció. Tres dels desinfectants més utilitzats a nivell europeu per tractar l’aigua de consum són el clor, la temperatura i la radiació UV. Tot i que el seu ús està regulat en nombroses normatives estatals, aquestes s’apliquen sense tenir en compte les amebes de vida lliure i les interrelacions que aquestes poden tenir amb altres microorganismes. L’objectiu principal d’aquest treball va ser estudiar l’eficàcia d’aquests tres desinfectants de l’aigua aplicant les mateixes condicions d’estudi sobre Legionella spp.; amebes de vida lliure en els dos estats de vida, trofozoïts i cists; i sobre els simbionts que estableixen Legionella i Acanthamoeba. En primer lloc es van obtenir soques de Legionella spp., i amebes de vida lliure de diferents orígens, tant ambientals com de col•lecció i es van optimitzar els protocols de cultiu dels diferents microorganismes, especialment pel que fa a les amebes. A continuació es van posar a punt mètodes quantitatius que ens permetessin comparar la viabilitat cel•lular després de cada tractament amb els tres desinfectants. I es van establir les condicions d’assaig per a cada un dels desinfectants. Finalment es van establir co-cultius per observar si l’associació entre Legionella i Acanthamoeba modificava d’alguna manera l’eficàcia dels desinfectant envers aquests dos microorganismes. La formació de co-cultius i el seu monitoreig mitjançant la tècnica del FISH ens va permetre observar com la soca de Legionella passava d’un estat plactònic a un estat d’emdosimbiont a l’interior dels trofozoïts. Analitzant la susceptibilitat de les diferents soques de Legionella, d’amebes de vida lliure, tan en estat de trofozoït com de cist, així com de Legionella com a endosimbiont d’Acanthamoeba per cadascun dels tractaments aplicats, es van proposar diferents models per descriure’n la cinètica d’inactivació. A partir d’aquí els resultats obtinguts es van comparar amb altres estudis publicats i se’n van extreure unes conclusions finals. Els resultats mostraren que clor, temperatura i radiació UV tenen un efecte desinfectant diferent pel que fa a les diferents soques de Legionella i amebes de vida lliure. Les diferències observades entre els diferents tractaments poden ser atribuïbles a la concentració de desinfectant, el temps d’exposició i a les diferències intrínseques de cada soca per cada microorganisme utilitzat. Pel que fa a la susceptibilitat de les amebes, trofozoïts i cists es van comportar de maneres diferents, sent els trofozoïts més sensibles que els cists. Finalment, L. pneumophila va resultar ser més resistent als tractaments amb desinfectants aplicats associada a trofozoïts d’Acanthamoeba en comparació amb el bacteri en condicions axèniques. Per tant, a l’hora d’aplicar tractaments de desinfecció, cal tenir en compte la complexa ecologia de Legionella com a endosimbiont d’amebes perquè aquests siguin eficaços i evitar així processos de recolonització.
Legionella infections are serious problem which causes concern to health public services in our country. Despite all measures and controls realized, most sporadic cases and outbreaks have been related to drinking water systems that have been subjected to one or more disinfection processes. Legionella spp., not only survive these treatments but multiplied over the distribution system becoming a potential environmental hazard. The main factors that promote Legionella survival and proliferation in water systems are the bacteria biology itself, since Legionella is able to survive under a wide range of environmental conditions, as well as the relationship that Legionella establishes with other microorganisms that live in the same habitat as protozoa. Protozoa, and specifically free-living amoebae of the genera Acanthamoeba and Hartmannella have been described as common inhabitants of drinking water distribution systems. These amoebae survive in front harsh environmental conditions by forming resistant structures called cysts. Amoebae feed mainly on bacteria which are engulfed by phagocitosis and digested intracellularly. However, some of these bacteria have developed some strategies to survive amoebae digestion and some of them, as Legionella are able to use host cellular resources to multiply within it. In addition, as an endosimbiont, Legionella remains protected from disinfectants which could lead to a rapid recolonization of water distribution systems once disinfection treatments have been applied. Three of the most commonly used water disinfectants in Europe for drinking water treatment are chlorine, temperature and UV radiation. Although its use is regulated by many national guidelines, its efficacy relies mainly on bacterial inactivation without considering other microorganisms such as free living amoebae and its relationships with other microorganisms as Legionella. Therefore, the main objective of this work was to study the effectiveness of these three water disinfectants applying the same study conditions, on Legionella spp.; free-living amoebae considering its two life stages; and on the simbionts between Legionella and Acanthamoeba. First of all, several strains of Legionella spp., and free-living amoebae from different origins (environmental and from culture collections) were obtained and culture protocols were optimized, especially for free-living amoebae. Second, test conditions were established for each of the disinfectants and a quantitative method was implemented in order to compare cell viability after every disinfection treatment. Finally, to see whether the association between Legionella and Acanthamoeba modifies the effectiveness of the three disinfectants towards these two types of microorganisms, co-cultures of Legionella and Acanthamoeba were realized. Co-culture formation was monitored by using a FISH method, which led us observe how axenic Legionella changed to an intracellular state within Acanthamoeba trophozoites. Analyzing the susceptibility of the Legionella spp. strains; free-living amoebae strains, either trophozoites and cysts stages; as well as Legionella as an Acanthamoeba endosymbiont, for each of the treatments applied, inactivation kinetics models were proposed. Results obtained were compared with studies published by other authors and final conclusions were considered. Results showed that, chlorine, temperature and UV radiation have a disinfectant effect on the different Legionella strains used, as well as on free living amoebae. Differences on the disinfectant effect could be atributted to disinfectant concentration, exposure time and strain intrinsic characteristics. Regarding free living amoeba, trophozoites and cysts had a significantly different behaviour, being trophozoites more sensitive to disinfectants than cysts. Finally, L. pneumophila as and endosymbiont of amoeba strains showed a greater resistance to disinfectant compared with the axenic state. Because of that, when applying disinfections treatments, the complex ecology of Legionella as an amoeba endosymbiont should be considered in order to prevent a system recolonization.
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35

Pires, Marco Roberto. "Desinfecção de esgotos com radiação ultravioleta : influencia da qualidade do efluente e da fotorreativação." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258116.

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Abstract:
Orientador: Jose Euclides Stipp Paterniani
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil
Made available in DSpace on 2018-08-02T03:02:10Z (GMT). No. of bitstreams: 1 Pires_MarcoRoberto_D.pdf: 5271302 bytes, checksum: 360fb9a15e870769155cec24f76d1dab (MD5) Previous issue date: 2002
Resumo: Desinfecção de esgotos com radiação ultravioleta vem sendo utilizado, principalmente, em países europeus e nos EUA. A fotorreativação dos microrganismos tem sido avaliada para determinar seu grau de interferência na desinfecção. Este trabalho teve como objetivo avaliar a radiação ultravioleta para diferentes qualidades de efluentes e estudar a fotorreativação. Foram utilizados dois reatores diferentes, sendo um com lâmpadas emersas e outro imersa. Os reatores foram testados em seis efluentes diferentes para quatro vazões diferentes para cada reator. Os coliformes totais e fecais foram analisados para avaliar a eficiência dos reatores. Ensaios de fotorreativação em condições controladas foram realizadas. De forma geral, o Reator I foi mais eficiente que o Reator TI, e a qualidade do efluente muitas vezes foi mais importante que a dose aplicada como apresentada no Ponto de Coleta 3 para coliformes fecais, em que a inativação foi maior para a vazão 4 (com menor tempo de exposição à luz) em vez de ocorrer para a vazão 1 (com maior tempo de exposição). Doses de radiação ultravioleta mais altas implicam em valores iniciais e finais de fotorreativação menores, porém para atingir o valor máximo necessita de mais tempo. Quanto maior a dose de radiação ultravioleta aplicada menor é o grau de fotorreativação; os coliformes totais tem melhor correlação para análises desta natureza quanto comparado com a E.co/i
Abstract: Disinfection of effluents with ultraviolet radiation has been used in Europeans countries and United States. The photoreactivation of microorganism have been estimated to determine the influence on the disinfection. The objective of this work had to evaluate the ultraviolet disinfection to different qualities of effluent and photoreactivation. Two different kinds of reactors were used in experimental analyzed. The reactors were tested to six different effluents for four flows. Total and fecal coliforms were analyzed to estimate the efficiency of reactors. Assays of photoreactivation were analyzed in controlled conditions. In most of case, the Reactor I was more efficient than Reactor II, and effluent quality was more important than the dose uv applied. Dose uv higher imply in initial and final values of lower photoreactivation. The total coliforms have better correlation than E.coli
Doutorado
Saneamento e Ambiente
Doutor em Engenharia Civil
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36

Högberg, Anna. "Analys av dricksvattenrening med metoderna Mikrobiologisk riskanalys, MRA och God desinfeksjonspraksis, GDP." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63106.

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Abstract:
Vatten är ett livsmedel som vi kommer i kontakt med dagligen. För att inte råka ut för sjuk-domar och infektioner renas dricksvattnet på vattenverken, främst för att reducera antalet patogener, d.v.s. sjukdomsframkallande mikroorganismer. Man brukar prata om tre grupper mikroorganismer i vattenrening; bakterier, virus och parasiter. Dessa grupper är vitt skilda i många avseenden och reduceras därför olika bra av olika reningssteg. Ju mer kunskap man kan få om reningsprocessen, desto bättre kan reningen optimeras. Därmed minimeras riskerna för konsumenterna att drabbas av infektioner. I det här arbetet används två modeller för att beskriva och utvärdera Borgs vattenverk som drivs av Norrköping Vatten AB. Modellen God desinfeksjonspraksis (GDP) är ett resultat av ett norskt projekt och baserar sig på formler och tabeller. Först avgörs råvattenkvaliteten genom att vattenverkets storlek och förekomst av mikroorganismer bedöms. Därefter görs diverse avdrag för förebyggande åtgärder, rening utöver desinfektion m.m. Slutligen bedöms desinfektionsgraden genom att det tillsatta klorets avklingning bestäms för beräkning av Ct-värdet; produkten av kontakttiden och koncentrationen. Genom att jämföra råvattenkvaliteten med avdragen och desinfektions-graden kan en bedömning göras om huruvida reningsprocessen är tillräcklig eller inte. I Mikrobiologisk riskanalys (MRA) bygger man upp en modell av sitt vattenverk i ett program och väljer patogenhalter för råvattnet. Efter det beräknar programmet renings-processens reduktion, riskerna för daglig respektive årlig sannolikhet för infektion samt DALYs, som gör att man kan jämföra risken för vattenburen smitta med exempelvis risken att förolyckas i trafiken. Det amerikanska naturvårdsverket och WHO har satt gränsen för den acceptabla årliga sannolikheten för infektion på grund av vattenrelaterad sjukdom till 1/10 000 invånare respektive 1 µDALYs. Fördelen med MRA är att när man väl byggt upp sitt vattenverk i programmet kan olika scenarion simuleras genom att patogenhalterna varieras. Tyvärr är det svårt att uppskatta patogenhalterna då de provtagningar som skulle behövas sällan är gjorda. Även litteraturvärden kan vara svårt att hitta, särskilt för virus som är så små att de är svåra att analysera. Resultatet av bägge modellerna visade på att Borgs vattenverks reduktionsförmåga är tillräcklig med avseende på bakterier, men inte för virus och parasiter. I MRA är det emellertid svårt att säga hur korrekt detta påstående är, då endast litteraturvärden kunnat användas för de två sistnämnda patogenerna. En del provtagningar har gjorts och då har inga parasiter kunnat påvisas i råvattnet, men för att inte underskatta riskerna användes litteratur-värdena ändå. GDP påvisade inga stora brister i reduceringen av virus och parasiter och i MRA låg resultatet i samma storleksordning som gränsen för DALYs. Eventuellt behöver alltså inga stora åtgärder vidtas för att minska de mikrobiologiska riskerna. De viktigaste stegen i reningsprocessen är långsamfiltrering, desinfektion med fritt klor och fällning och sedimentering med efterföljande filtrering. Infektionsrisken blir störst om fällningssteget slås ut. I samtliga simulerade scenarion låg infektionssannolikheten för bakterier fortfarande på en acceptabel nivå. Det värsta scenariot av de modellerade är om avloppsledningen från Skärblacka skulle börja läcka samtidigt som det regnar kraftigt. Det skulle leda till att förorening från betesmark spolas med ut i Motala Ström där råvattnet hämtas. Detta ger den högsta patogenhalten och därmed också den största infektionsrisken.
Water is one of the most basic things in life and is something we come in contact with on a daily basis. To prevent diseases and infections, the drinking water is purified, mainly in order to reduce the number of pathogens. The most important groups of microorganisms in water purification are bacteria, viruses, and parasites. These groups are very different in many respects and are therefore reduced most efficiently by different purification processes. If more knowledge is gained, the waterworks can optimize the purification process. This would lead to a minimization of the risk of getting infections caused by consuming the drinking water. In this paper two models are used to describe and evaluate Borg’s waterworks, run by Norrköping Vatten AB. Good Disinfection Practice (GDP) is the result of a Norwegian project and is based on formulas and tables. First, the raw water quality is determined by evaluating the presence of microorganisms and the number of people supplied. Then deductions are made due to security precautions and water treatment besides disinfection etc.  Finally the disinfection is determined by calculating the reduction of the added chlorine to gain the Ct-value, which is the product of the contact time and concentration. By comparison of the raw water, the deductions and the disinfection, the purification process can be evaluated as sufficient or not. In Quantitative Microbial Risk Assessment (QMRA) the purification process is modelled and concentrations of pathogens in the raw water are chosen. The program then calculates the reduction of the pathogens by the purification process. The result is also presented as probability of daily or annual infection and DALYs, which makes it possible to compare the risks of waterborne diseases with for example, the risk of traffic accidents. The US Environmental Protection Agency and the World Health Organization have determined the limit for the acceptable annual probability of infection due to water-related disease to 1/10,000 and 1 µDALYs. The advantage of the QMRA is that once you have modelled your purification process a variety of scenarios can be simulated. Unfortunately, it is difficult to estimate the concentrations of pathogens in the raw water and the acquired analysis are rarely made. Even literature values can be difficult to find, especially for viruses due to the difficulties in analysing them because of their small size. Both the models’ results showed that Borg’s waterworks reduction capacity is sufficient for bacteria, but not viruses and parasites. It is however difficult to say how accurate this conclusion is. In QMRA only literature values have been used as a basis to determine the risk for viruses and parasites. In fact, no parasites have been found when samples have been run on the raw water. But since an overestimation of the risk is to be preferred, literature values were used anyway. GDP showed only small shortcomings in the reduction of viruses and parasites and the values obtained from QMRA were in the same order of magnitude as the limit of DALYs. Therefore only small measures might be needed to lower the microbiological risks. The most important steps in the purification process are slow sand filtration, disinfection with free chlorine and precipitation and sedimentation with subsequent filtering. Elimination of the precipitating step results in the greatest risk of infection. In all the scenarios simulated the likelihood of infections caused by bacteria is still acceptable.  The worst-case scenario would be a sewage water leak during heavy raining. The rain would cause excrement from cattle to be washed into and contaminate the raw water in addition to the sewage contamination. This provides the highest concentration of pathogens in the raw water and therefore also the greatest risk of infection.
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37

"Disinfection of wastewater bacteria by photocatalytic oxidation." 2008. http://library.cuhk.edu.hk/record=b5893433.

Full text
Abstract:
So, Wai Man.
Thesis submitted in: October 2007.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2008.
Includes bibliographical references (leaves 112-124).
Abstracts in English and Chinese.
Acknowledgements --- p.i
Abstract --- p.ii
Table of Contents --- p.vi
List of Figures --- p.x
List of Plates --- p.viii
List of Tables X --- p.v
Abbreviations --- p.xvii
Equations --- p.xix
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Importance of water disinfection --- p.1
Chapter 1.2 --- Conventional disinfection methods --- p.2
Chapter 1.2.1 --- Chlorination --- p.2
Chapter 1.2.2 --- Ozonation --- p.3
Chapter 1.2.3 --- Ultraviolet-C (UV-C) irradiation --- p.4
Chapter 1.2.4 --- Sunlight irradiation --- p.5
Chapter 1.2.5 --- Others --- p.6
Chapter 1.3 --- Photocatalytic oxidation --- p.7
Chapter 1.3.1 --- Reactions in PCO --- p.8
Chapter 1.3.2 --- Disinfection mechanism of PCO --- p.11
Chapter 1.3.3 --- Photocatalysts --- p.14
Chapter 1.3.3.1 --- Titanium dioxide (TiO2) --- p.14
Chapter 1.3.3.2 --- Modification of TiO2 --- p.15
Chapter 1.3.3.2.1 --- Sulphur cation-doped TiO2 (S-TiO2) --- p.17
Chapter 1.3.3.2.2 --- Copper(I) oxide-sensitized P-25 (Cu20/P-25) --- p.18
Chapter 1.3.3.2.3 --- Silicon dioxide-doped TiO2 (SiO2-TiO2) --- p.18
Chapter 1.3.3.2.4 --- Nitrogen-doped TiO2 (N-TiO2) --- p.19
Chapter 1.4 --- Bacterial defense systems against oxidative stress --- p.20
Chapter 1.5 --- Bacterial species --- p.22
Chapter 1.5.1 --- Salmonella typhimurium --- p.23
Chapter 1.5.2 --- Klebsiella pneumoniae --- p.24
Chapter 1.5.3 --- Bacillus thuringiensis --- p.25
Chapter 1.5.3 --- Bacillus pasteurii --- p.26
Chapter 2. --- Objectives --- p.27
Chapter 3. --- Material and Methods --- p.28
Chapter 3.1 --- Culture media and diluents --- p.28
Chapter 3.2 --- Screening of target bacteria --- p.28
Chapter 3.3 --- PCO disinfection reaction --- p.29
Chapter 3.3.1 --- Photocatalysts --- p.29
Chapter 3.3.2 --- Bacterial cultures --- p.31
Chapter 3.3.3 --- PCO reactor --- p.32
Chapter 3.3.4 --- PCO efficacy test --- p.34
Chapter 3.3.5 --- Comparison of different photocatalysts --- p.35
Chapter 3.4 --- Optimization of PCO disinfection conditions --- p.35
Chapter 3.5 --- Transmission electron microscopy (TEM) --- p.39
Chapter 3.6 --- Superoxide dismutase (SOD) activity assay --- p.42
Chapter 3.7 --- Catalase (CAT) activity assay --- p.44
Chapter 3.8 --- Spore staining --- p.45
Chapter 3.9 --- Atomic absorption spectrophotometry (AAS) --- p.45
Chapter 3.10 --- X-ray photoelectron spectrometry (XPS) --- p.46
Chapter 4. --- Results --- p.47
Chapter 4.1 --- Screening of wastewater bacteria --- p.47
Chapter 4.2 --- PCO efficacy test --- p.49
Chapter 4.3 --- PCO under visible light irradiation --- p.53
Chapter 4.3.1 --- Fluorescence lamps with UV filter --- p.53
Chapter 4.3.2 --- Solar lamp with UV filter --- p.61
Chapter 4.3.3 --- Sunlight with UV filter --- p.67
Chapter 4.4 --- Optimization of PCO disinfection conditions --- p.75
Chapter 4.4.1 --- Effect of visible light intensities --- p.75
Chapter 4.4.2 --- Effect of photocatalyst concentrations --- p.77
Chapter 4.4.3 --- Optimized conditions --- p.79
Chapter 4.5 --- Transmission electron microscopy (TEM) --- p.79
Chapter 4.6 --- Superoxide dismutase (SOD) activity assay --- p.83
Chapter 4.7 --- Catalase (CAT) activity assay --- p.84
Chapter 4.8 --- Spore staining --- p.85
Chapter 4.9 --- Studies on Cu20/P-25 --- p.88
Chapter 4.9.1 --- Atomic absorption spectrophotometry (AAS) --- p.88
Chapter 4.9.2 --- X-ray photoelectron spectrometry (XPS) --- p.88
Chapter 5. --- Discussion --- p.90
Chapter 5.1 --- Screening of wastewater bacteria --- p.90
Chapter 5.2 --- PCO efficacy test --- p.90
Chapter 5.3 --- Comparison between different light sources --- p.90
Chapter 5.4 --- Comparison between different photocatalysts --- p.93
Chapter 5.5 --- Optimization of PCO disinfection conditions --- p.95
Chapter 5.5.1 --- Effect of visible light intensities --- p.95
Chapter 5.5.2 --- Effect of photocatalyst concentrations --- p.96
Chapter 5.6 --- Transmission electron microscopy (TEM) --- p.97
Chapter 5.7 --- Comparison between different bacterial species --- p.99
Chapter 5.8 --- Possible factors affecting susceptibility of bacteria towards PCO --- p.99
Chapter 5.8.1 --- Formation of endospores --- p.99
Chapter 5.8.2 --- Differences in cell wall structure --- p.100
Chapter 5.8.3 --- SOD and CAT activities --- p.101
Chapter 5.9 --- Dark control of Cu20/P-25 --- p.103
Chapter 5.10 --- Studies on Cu20/P-25 --- p.104
Chapter 6. --- Conclusion --- p.107
Chapter 7. --- References --- p.112
Chapter 8. --- Appendix --- p.125
Chapter 8.1 --- Production of S-Ti02 --- p.125
Chapter 8.2 --- Production of Si02-Ti02 --- p.125
Chapter 8.3 --- Production of N-Ti02 --- p.125
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38

"Disinfection of bacteria by photocatalytic oxidation." 2006. http://library.cuhk.edu.hk/record=b5892910.

Full text
Abstract:
Wong Man Yung.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 106-120).
Abstracts in English and Chinese.
Acknowledgements --- p.i
Abstract --- p.ii
Table of Contents --- p.vi
List of Figures --- p.xi
List of Plates --- p.xiii
List of Tables --- p.xv
Abbreviations --- p.xvi
Equations --- p.xviii
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Water disinfection --- p.1
Chapter 1.2 --- Bacterial species --- p.2
Chapter 1.2.1 --- Staphylococcus saprophyticus --- p.2
Chapter 1.2.2 --- Enterobacter cloacae --- p.3
Chapter 1.3 --- Disinfection methods --- p.4
Chapter 1.3.1 --- Physical methods --- p.4
Chapter 1.3.1.1 --- UV-C irradiation --- p.4
Chapter 1.3.1.2 --- Solar disinfection --- p.5
Chapter 1.3.2 --- Chemical methods --- p.6
Chapter 1.3.2.1 --- Chlorination --- p.6
Chapter 1.3.2.2 --- Ozonation --- p.7
Chapter 1.3.2.3 --- Mixed disinfectants --- p.8
Chapter 1.3.3 --- Other disinfection methods --- p.8
Chapter 1.4 --- Advanced oxidation processes (AOPs) --- p.9
Chapter 1.5 --- Photocatalytic oxidation (PCO) --- p.10
Chapter 1.5.1 --- PCO process --- p.12
Chapter 1.5.2 --- Photocatalysts --- p.14
Chapter 1.5.2.1 --- Titanium dioxide (P25) --- p.15
Chapter 1.5.2.2 --- Silver sensitized P25 (Ag/P25) --- p.16
Chapter 1.5.2.3 --- Silicon dioxide doped titanium dioxide (SiO2-TiO2) --- p.17
Chapter 1.5.2.4 --- Copper(I) oxide sensitized P25 (Cu2O/P25) --- p.18
Chapter 1.5.3 --- Irradiation sources --- p.19
Chapter 1.5.4 --- PCO disinfection mechanisms --- p.20
Chapter 1.6 --- Bacterial defense mechanisms against oxidative stress --- p.22
Chapter 2. --- Objectives --- p.25
Chapter 3. --- Materials and Methods --- p.26
Chapter 3.1 --- Chemicals --- p.26
Chapter 3.2 --- Bacterial culture --- p.26
Chapter 3.3 --- Photocatalytic reactor --- p.27
Chapter 3.4 --- PCO efficacy test --- p.30
Chapter 3.5 --- Optimization of PCO conditions --- p.31
Chapter 3.5.1 --- Effect of P25 concentrations --- p.31
Chapter 3.5.2 --- Effect of UV intensities --- p.32
Chapter 3.5.3 --- Combinational study of P25 concentrations and UV intensities --- p.32
Chapter 3.5.4 --- Effect of stirring rates --- p.32
Chapter 3.5.5 --- Effect of initial cell concentrations --- p.33
Chapter 3.6 --- PCO disinfection using different photocatalysts --- p.33
Chapter 3.6.1 --- Effect of CU2O/P25 concentrations --- p.33
Chapter 3.6.2 --- Effect of CU2O powder on the two bacterial species --- p.33
Chapter 3.7 --- Transmission electron microscopy (TEM) --- p.34
Chapter 3.8 --- Catalase (CAT) test --- p.37
Chapter 3.9 --- Superoxide dismutase (SOD) activity assay --- p.39
Chapter 4. --- Results --- p.40
Chapter 4.1 --- Efficacy test --- p.40
Chapter 4.2 --- PCO disinfection under UV irradiation --- p.40
Chapter 4.2.1 --- Control experiments --- p.40
Chapter 4.2.2 --- Optimization of PCO conditions using P25 as a photocatalyst --- p.42
Chapter 4.2.2.1 --- Effect of P25 concentrations --- p.42
Chapter 4.2.2.2 --- Effect of UV intensities --- p.45
Chapter 4.2.2.3 --- Combinational study of P25 concentrations and UV intensities --- p.48
Chapter 4.2.2.4 --- Effect of stirring rates --- p.54
Chapter 4.2.2.5 --- Effect of initial cell concentrations --- p.57
Chapter 4.2.3 --- Comparison of PCO inactivation efficiency between S. saprophyticus and E. cloacae --- p.60
Chapter 4.2.4 --- PCO disinfection using different photocatalysts --- p.62
Chapter 4.2.4.1 --- Control experiments --- p.62
Chapter 4.2.4.2 --- Ag/P25 --- p.62
Chapter 4.2.4.3 --- SiO2-TiO2 --- p.64
Chapter 4.2.4.4 --- Cu2O/P25 --- p.64
Chapter 4.3 --- PCO disinfection under visible light irradiation --- p.66
Chapter 4.3.1 --- Effect of Cu2O/P25 concentrations --- p.67
Chapter 4.3.2 --- Effect of CU2O powder on the two bacterial species --- p.70
Chapter 4.4 --- Feasibility use of indoor light (fluorescent lamps) for PCO disinfection --- p.71
Chapter 4.5 --- Transmission electron microscopy (TEM) --- p.74
Chapter 4.5.1 --- Morphological changes induced by PCO using P25 as a photocatalyst --- p.74
Chapter 4.5.2 --- Morphological changes induced by PCO using Cu2O/P25 as a photocatalyst --- p.77
Chapter 4.6 --- Catalase (CAT) test --- p.80
Chapter 4.7 --- Superoxide dismutase (SOD) activity assay --- p.82
Chapter 5. --- Discussion --- p.83
Chapter 5.1 --- Efficacy test --- p.83
Chapter 5.2 --- PCO disinfection under UV irradiation --- p.83
Chapter 5.2.1 --- Optimization study --- p.84
Chapter 5.2.1.1 --- Effect of P25 concentrations --- p.84
Chapter 5.2.1.2 --- Effect of UV intensities --- p.85
Chapter 5.2.1.3 --- Combinational study of P25 concentrations and UV intensities --- p.86
Chapter 5.2.1.4 --- Effect of stirring rates --- p.86
Chapter 5.2.1.5 --- Effect of initial cell concentrations --- p.87
Chapter 5.2.2 --- Comparison of PCO inactivation efficiency between S. saprophyticus and E. cloacae --- p.88
Chapter 5.2.3 --- PCO disinfection using different photocatalysts --- p.89
Chapter 5.2.3.1 --- Ag/P25 --- p.89
Chapter 5.2.3.2 --- SiO2-TiO2 and Cu2O/P25 --- p.90
Chapter 5.3 --- PCO disinfection under visible light irradiation --- p.90
Chapter 5.3.1 --- Effect of Cu20/P25 concentrations --- p.91
Chapter 5.3.2 --- Effect of CU2O powder on the two bacterial species --- p.92
Chapter 5.4 --- Feasibility use of fluorescent lamps for PCO disinfection --- p.93
Chapter 5.5 --- Transmission electron microscopy (TEM) --- p.95
Chapter 5.5.1 --- Morphological changes induced by PCO using P25 as a photocatalyst --- p.95
Chapter 5.5.2 --- Morphological changes induced by PCO using CU2O/P25 as a photocatalyst --- p.96
Chapter 5.6 --- Catalase (CAT) test --- p.98
Chapter 5.7 --- Superoxide dismutase (SOD) activity assay --- p.99
Chapter 6. --- Conclusion --- p.101
Chapter 7. --- References --- p.106
Chapter 8. --- Appendix --- p.121
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39

"Visible-light-driven photocatalysts for bacterial disinfection: bactericidal performances and mechanisms." 2012. http://library.cuhk.edu.hk/record=b5549674.

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Abstract:
在過去的幾十年中，人們越來越關心由致病微生物引起的水傳播疾病的爆發。作為一種綠色技術，太陽能光催化在不引起二次污染的殺滅各種致病微生物方面引起了廣泛關注。但是，目前最廣泛應用的TiO₂光催化劑僅在紫外光激發範圍內有效，而紫外光僅占太陽光譜的4%。因為太陽光譜中有45%是可見光，所以新型可見光催化劑的開發是現今光催化技術亟待解決的問題。另一方面，目前對於光催化殺菌機理的研究報導非常稀少而且主要集中于紫外-TiO₂光催化系統中，而對於可見光催化系統中的殺菌機理研究還鮮有報導。
本研究介紹三種新型可見光催化劑的殺菌性能。它們是B,Ni共摻TiO₂微米球（BNT），BiVO₄納米管（BV-NT）和CdIn₂S₄微米球（CIS）。其中一種是修飾的TiO₂催化劑，另兩種是新型的非TiO₂基催化劑。採用加入各種湮滅劑結合一種分離裝置的研究方法系統研究了三種催化劑的可見光殺菌機理。首先，研究發現當用BNT作為光催化劑的時候，可見光催化降解染料和殺菌之間存在巨大的差異。對於光催化降解染料，光催化反應主要發生在催化劑的表面，是由表面活性物質如h⁺, ・OHs和・O₂⁻參與，而細菌可以被擴散物種如・OH[subscript b]和H₂O₂，以不直接接觸催化劑表面的方式被殺死。可擴散的H₂O₂在這種殺菌過程中起了最重要的作用，而它可以在催化劑價帶以・OH[subscript b]溶液體相耦合和・OH[subscript s]催化劑表面耦合兩種方式產生。
其次，在用BV-NT作為光催化劑可見光殺滅大腸桿菌的過程中，光生空穴（h⁺）以及由空穴產生的氧化物種，如・OH[subscript s], H₂O₂和・HO₂/・O₂⁻，是主要的活性物種。但是這個殺菌過程只有很少量的H₂O₂可以擴散到溶液中，導致有效殺菌需要細菌和光催化表面直接接觸。研究還發現，細菌本身可以捕獲光生電子（e⁻）來降低空穴-電子複合率，這個作用在無氧氣參與的殺菌過程中尤為明顯。透射電鏡顯示，細菌的破壞是由細胞壁開始從外到內的被破壞。研究認為，表面羥基・OH[subscript s]比溶液體相羥基・OH[subscript b]更加重要，並且很難從BV-NT表面擴散進容易中。
最後，研究還發現CIS也具有不接觸細菌而有效可見光催化殺滅大腸桿菌的能力，這也歸結為可擴散H₂O₂，而不是・OH的作用。H₂O₂可以通過・O₂⁻從催化劑導帶和價帶同時產生。本研究提供了幾種具有應用前景的高效可見光催化殺菌催化劑，並對其光催化機理提出了新的思路，指出可見光催化殺菌機理與使用的光催化劑是密切相關的。更重要的是，本研究建立了一種簡便易行的研究方法，可用於對其他各種可見光催化殺菌系統進行深入的機理研究。
During the last few decades, there has been an increasing public concern related to the outbreak of waterborne diseases caused by pathogenic microorganisms. As a green technology, solar photocatalysis has attracted much attention for the disinfection of various microorganisms without secondary pollution. However, the most commonly used TiO₂ photocatalyst is only active under UV irradiation which accounts for only 4% of the solar spectrum. Therefore, new types of photocatalysts that can be excited by visible light (VL) are highly needed, as 45% of the solar spectrum is covered by VL. In addition, existing reports on the mechanisms of photocatalytic bacterial disinfection are rather limited and mostly based on TiO₂-UV irradiated systems, thus the mechanisms in visible-light-driven (VLD) photocatalystic disinfection systems are far from fully understandable.
In this study, three different kinds of VLD photocatalysts were discovered for the photocatalytic bacterial disinfection. They were B-Ni-codoped TiO₂ microsphere (BNT), bismuth vanadate nanotube (BV-NT), and cadmium indium sulfide (CIS). One was modified TiO₂-based photocatalyst, and the other two were new types of non-TiO₂ based photocatalyst. The mechanisms of VLD photocatalytic disinfection were investigated by multiple scavenging studies combined with a partition system. Firstly, significant differences between VLD photocatalytic dye decolorization and bacterial disinfection were found in the case of BNT as the photocatalyst. For photocatalytic dye decolorization, the reaction mainly occurred on the photocatalyst surface with the aid of surface-bounded reactive species (h⁺, ・OH[subscript s] and ・O₂⁻), while bacterial cell could be inactivated by diffusing reactive oxidative species such as ・OH[subscript b] and H₂O₂ without the direct contact with the photocatalyst. The diffusing H₂O₂ played the most important role in the photocatalytic disinfection, which could be produced both by the coupling of ・OH[subscript b] in bulk solution and ・OH[subscript s] on the surface of photocatalyst at the valence band.
Secondly, when using BV-NT as the photocatalyst for Escherichia coli K-12 inactivation, the photogenerated h⁺ and reactive oxidative species derived from h⁺, such as ・OH[subscript s], H₂O₂ and ・HO₂/・O₂⁻, were the major reactive species. However, the inactivation requires close contact between the BV-NT and bacterial cells, as only a limited amount of H₂O₂ can diffuse into the solution to cause the inactivation. The bacterial cells can trap e⁻ in order to minimize e⁻-h⁺ recombination, especially under anaerobic condition. Transmission electron microscopic study indicated the destruction process of bacterial cell began from the cell wall to other cellular components. The ・OH[subscript s] was postulated to be more important than ・OH[subscript b] and was not supposed to be released very easily from BV-NT surface.
Finally, it was found that E. coli cells could be effectively inactivated without the direct contact with CIS, which was attributed to the function of diffusing H₂O₂ rather than ・OH. H₂O₂ was produced from both conduction and valance bands with the involvement of ・O₂⁻, which were detected by ESR spin-trap with DMPO trapping technology. While this study provided promising candidates of efficient VLD photocatalysts for water disinfection as well as deep insights into the disinfection mechanisms, it was notable that the photocatalytic disinfection mechanisms were quite dependent on the selected photocatalysts. Nevertheless, the research methodology established in this study was proved to be facile and versatile for the in-depth investigation of mechanisms in different VLD photocatalyst systems.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Wang, Wanjun.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 140-170).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
Acknowledgements --- p.i
Abstract --- p.vi
List of Figures --- p.xvi
List of Plates --- p.xxiii
List of Tables --- p.xxiv
List of Equations --- p.xxv
Abbreviations --- p.xxvii
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Water disinfection --- p.1
Chapter 1.2 --- Traditional water disinfection methods --- p.2
Chapter 1.2.1 --- Chlorination --- p.2
Chapter 1.2.2 --- Ozonation --- p.3
Chapter 1.2.3 --- UV irradiation --- p.4
Chapter 1.3 --- Advanced oxidation process --- p.5
Chapter 1.4 --- Photocatalysis --- p.6
Chapter 1.4.1 --- Fundamental mechanism for TiO₂ photocatalysis --- p.7
Chapter 1.4.2 --- Photocatalytic water disinfection --- p.12
Chapter 1.5 --- Visible-light-driven photocatalysts for water disinfection --- p.16
Chapter 1.5.1 --- Modified TiO₂ photocatalysts --- p.16
Chapter 1.5.1.1 --- Surface modication of TiO₂ by noble metals --- p.16
Chapter 1.5.1.2 --- Ion doped TiO₂ --- p.18
Chapter 1.5.1.3 --- Dye-sensitized TiO₂ --- p.19
Chapter 1.5.1.4 --- Composite TiO₂ --- p.20
Chapter 1.5.2 --- Non-TiO₂ based photocatalysts --- p.22
Chapter 1.5.2.1 --- Metal oxides --- p.22
Chapter 1.5.2.2 --- Metal sulfides --- p.24
Chapter 1.5.2.3 --- Bismuth metallates --- p.25
Chapter 1.6 --- Photocatalystic disinfection mechanisms --- p.27
Chapter 2 --- Objectives --- p.30
Chapter 3 --- Comparative Study of Visible-light-driven Photocatalytic Mechanisms of Dye Decolorization and Bacterial Disinfection by B-Ni-codoped TiO₂ Microspheres --- p.32
Chapter 3.1 --- Introduction --- p.32
Chapter 3.2 --- Experimental --- p.35
Chapter 3.2.1 --- Materials --- p.35
Chapter 3.2.2 --- Characterizations --- p.36
Chapter 3.2.3 --- Photocatalytic decolorization of RhB --- p.36
Chapter 3.2.4 --- Photocatalytic disinfection of E. coli K-12 --- p.37
Chapter 3.2.5 --- Partition system --- p.40
Chapter 3.2.6 --- Scavenging study --- p.41
Chapter 3.2.7 --- Analysis of ・OH and ・O₂⁻ --- p.42
Chapter 3.2.8 --- Analysis of H₂O₂ --- p.43
Chapter 3.3 --- Results and Discussion --- p.44
Chapter 3.3.1 --- XRD and SEM images --- p.44
Chapter 3.3.2 --- Photocatalytic decolorization of RhB --- p.46
Chapter 3.3.2.1 --- Role of reactive species --- p.46
Chapter 3.3.2.2 --- Partition system for dye decolorization --- p.49
Chapter 3.3.3 --- Photocatalytic bacterial disinfection --- p.51
Chapter 3.3.3.1 --- Role of reactive species --- p.51
Chapter 3.3.3.2 --- Partition system for bacterial disinfection --- p.54
Chapter 3.3.3.3 --- pH effects --- p.58
Chapter 3.3.3.4 --- Role of H₂O₂ --- p.60
Chapter 3.3.4 --- Role of ・O₂⁻ in RhB decolorization and bacterial disinfection --- p.67
Chapter 3.4 --- Conclusions --- p.75
Chapter 4. --- Visible-light-driven Photocatalytic Inactivation of E. coli K-12 by Bismuth Vanadate Nanotubes: Bactericidal Performance and Mechanism --- p.76
Chapter 4.1 --- Introduction --- p.76
Chapter 4.2 --- Experimental --- p.78
Chapter 4.2.1 --- Materials --- p.78
Chapter 4.2.2 --- Photocatalytic bacterial inactivation --- p.80
Chapter 4.2.3 --- Bacterial regrowth ability test --- p.82
Chapter 4.2.4 --- Analysis of reactive species --- p.82
Chapter 4.2.5 --- Preparation procedure for bacterial TEM study --- p.83
Chapter 4.2.6 --- Analysis of bacterial catalase activity --- p.84
Chapter 4.2.7 --- Analysis of potassium ion leakage --- p.84
Chapter 4.3 --- Results and Discussion --- p.85
Chapter 4.3.1 --- Photocatalytic bacterial inactivation --- p.85
Chapter 4.3.2 --- Mechanism of photocatalytic inactivation --- p.87
Chapter 4.3.2.1 --- Role of primary reactive species --- p.87
Chapter 4.3.2.2 --- Role of direct contact effect --- p.96
Chapter 4.3.3 --- Destruction model of bacterial cells --- p.98
Chapter 4.3.4 --- Analysis of radical production --- p.104
Chapter 4.4 --- Conclusions --- p.109
Chapter 5 --- CdIn₂S₄ Microsphere as an Efficient Visible-light-driven Photocatalyst for Bacterial Inactivation: Synthesis, Characterizations and Photocatalytic Inactivation Mechanisms --- p.111
Chapter 5.1 --- Introduction --- p.111
Chapter 5.2 --- Experimental --- p.113
Chapter 5.2.1 --- Synthesis --- p.113
Chapter 5.2.2 --- Characterizations --- p.114
Chapter 5.2.3 --- Photocatalytic bacterial inactivation --- p.116
Chapter 5.3 --- Results and Discussion --- p.117
Chapter 5.3.1 --- Characterizations of Photocatalyst --- p.117
Chapter 5.3.2 --- Photocatalytic bacterial inactivation and mechanism --- p.121
Chapter 5.3.3 --- Destruction process of bacterial cell --- p.128
Chapter 5.3.4 --- Analysis of radical generation --- p.131
Chapter 5.4 --- Conclusions --- p.133
Chapter 6 --- General Conclusions --- p.135
Chapter 7 --- References --- p.140
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40

Loeb, Stephanie. "Nanostructured Photocatalysis for Water Purification." Thesis, 2013. http://hdl.handle.net/1807/43101.

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Abstract:
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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41

"Photocatalytic disinfection towards freshwater and marine bacteria using fluorescent light." 2008. http://library.cuhk.edu.hk/record=b5893609.

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Abstract:
Leung, Tsz Yan.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2008.
Includes bibliographical references (leaves 132-146).
Abstracts in English and Chinese.
Acknowledgements --- p.i
Abstract --- p.ii
Table of Contents --- p.vii
List of Figures --- p.xii
List of Plates --- p.xiv
List of Tables --- p.xvii
Abbreviations --- p.xviii
Equations --- p.xxi
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Water crisis and water disinfection --- p.1
Chapter 1.2 --- Common disinfection methods --- p.2
Chapter 1.2.1 --- Chlorination --- p.2
Chapter 1.2.2 --- Ozonation --- p.4
Chapter 1.2.3 --- Ultraviolet-C (UV-C) irradiation --- p.6
Chapter 1.2.4 --- Solar disinfection (SODIS) --- p.7
Chapter 1.2.5 --- Mixed disinfectants --- p.9
Chapter 1.2.6 --- Other disinfection methods --- p.10
Chapter 1.3 --- Advanced oxidation processes (AOPs) --- p.11
Chapter 1.4 --- Photocatalytic oxidation (PCO) --- p.13
Chapter 1.4.1 --- Understanding of PCO process --- p.15
Chapter 1.4.2 --- Proposed disinfection mechanism of PCO --- p.18
Chapter 1.4.3 --- Titanium dioxide (Ti02) photocatalyst --- p.21
Chapter 1.4.4 --- Irradiation sources --- p.22
Chapter 1.4.5 --- Bacterial species --- p.23
Chapter 1.4.5.1 --- Escherichia coli K12 --- p.23
Chapter 1.4.5.2 --- Shigella sonnei --- p.24
Chapter 1.4.5.3 --- Alteromonas alvinellae --- p.25
Chapter 1.4.5.4 --- Photobacterium phosphoreum --- p.26
Chapter 1.4.6 --- Bacterial defense mechanism towards oxidative stress --- p.27
Chapter 1.4.6.1 --- Superoxide dismutase (SOD) activity --- p.28
Chapter 1.4.6.2 --- Catalase (CAT) activity --- p.29
Chapter 1.4.6.3 --- Fatty acid (FA) profile --- p.30
Chapter 1.4.7 --- Significance of the project --- p.31
Chapter 2. --- Objectives --- p.34
Chapter 3. --- Material and Methods --- p.36
Chapter 3.1 --- Chemicals --- p.36
Chapter 3.2 --- Screening of freshwater and marine bacterial culture --- p.36
Chapter 3.3 --- Photocatalytic reaction --- p.39
Chapter 3.3.1 --- Preparation of reaction mixture --- p.39
Chapter 3.3.2 --- Preparation of bacterial culture --- p.39
Chapter 3.3.3 --- Photocatalytic reactor --- p.41
Chapter 3.3.4 --- PCO disinfection reaction --- p.42
Chapter 3.3.4.1 --- Effect of initial pH --- p.44
Chapter 3.3.4.2 --- Effect of reaction temperature --- p.45
Chapter 3.3.4.3 --- Effect of growth phases --- p.45
Chapter 3.4 --- Measurement of superoxide dismutase (SOD) activity --- p.47
Chapter 3.5 --- Measurement of catalase (CAT) activity --- p.49
Chapter 3.6 --- Fatty acid (FA) profile --- p.50
Chapter 3.7 --- Bacterial regrowth test --- p.51
Chapter 3.8 --- Atomic absorption spectrophotometry (AAS) --- p.52
Chapter 3.9 --- Total organic carbon (TOC) analysis --- p.53
Chapter 3.10 --- Chlorination --- p.55
Chapter 3.11 --- UV-C irradiation --- p.56
Chapter 3.12 --- Transmission electron microscopy (TEM) --- p.56
Chapter 4. --- Results --- p.60
Chapter 4.1 --- Screening of UV-A resistant freshwater and marine bacteria --- p.60
Chapter 4.2 --- Control experiments --- p.62
Chapter 4.3 --- Treatment experiments --- p.65
Chapter 4.3.1 --- UV-A irradiation from lamps --- p.65
Chapter 4.3.2 --- Fluorescent light from fluorescent lamps --- p.65
Chapter 4.3.3 --- Effect of initial pH --- p.67
Chapter 4.3.4 --- Effect of reaction temperature --- p.70
Chapter 4.3.5 --- Effect of growth phases --- p.70
Chapter 4.4 --- Factors affecting bacterial sensitivity towards PCO --- p.73
Chapter 4.4.1 --- Superoxide dismutase (SOD) and catalase (CAT) activities --- p.73
Chapter 4.4.2 --- Superoxide dismutase (SOD) and catalase (CAT) induction --- p.74
Chapter 4.4.3 --- Fatty acid (FA) profile --- p.75
Chapter 4.5 --- Bacterial regrowth test --- p.78
Chapter 4.6 --- Disinfection mechanisms of fluorescent light-driven photocatalysis --- p.79
Chapter 4.6.1 --- Atomic absorption spectrophotometry (AAS) --- p.79
Chapter 4.6.2 --- Total organic carbon (TOC) analysis --- p.81
Chapter 4.6.3 --- Transmission electron microscopy (TEM) --- p.83
Chapter 4.7 --- Chlorination --- p.89
Chapter 4.7.1 --- Disinfection efficiency --- p.89
Chapter 4.7.2 --- Transmission electron microscopy (TEM) --- p.92
Chapter 4.8 --- UV-C irradiation --- p.96
Chapter 4.8.1 --- Disinfection efficiency --- p.96
Chapter 4.8.2 --- Transmission electron microscopy (TEM) --- p.96
Chapter 5. --- Discussions --- p.103
Chapter 5.1 --- Screening of UV-A resistant freshwater and marine bacteria --- p.103
Chapter 5.2 --- Comparison of PCO coupled with UV-A lamps and fluorescent lamps --- p.103
Chapter 5.3 --- Effect of initial pH --- p.105
Chapter 5.4 --- Effect of reaction temperature --- p.106
Chapter 5.5 --- Effect of growth phases --- p.107
Chapter 5.6 --- Factors affecting bacterial sensitivity towards PCO --- p.108
Chapter 5.6.1 --- Superoxide dismutase (SOD) and catalase (CAT) activities --- p.108
Chapter 5.6.2 --- Superoxide dismutase (SOD) and catalase (CAT) induction --- p.110
Chapter 5.6.3 --- Fatty acid (FA) profile --- p.110
Chapter 5.6.4 --- Cell wall structure --- p.112
Chapter 5.6.5 --- Bacterial size --- p.114
Chapter 5.6.6 --- Other possible factors --- p.114
Chapter 5.7 --- Bacterial regrowth test --- p.115
Chapter 5.8 --- Disinfection mechanisms of fluorescent light-driven photocatalysis --- p.116
Chapter 5.8.1 --- Atomic absorption spectrophotometry (AAS) --- p.116
Chapter 5.8.2 --- Total organic carbon (TOC) analysis --- p.117
Chapter 5.8.3 --- Transmission electron microscopy (TEM) --- p.118
Chapter 5.9 --- Chlorination --- p.122
Chapter 5.9.1 --- Disinfection efficiency --- p.122
Chapter 5.9.2 --- Transmission electron microscopy (TEM) --- p.122
Chapter 5.10 --- UV-C irradiation --- p.123
Chapter 5.10.1 --- Disinfection efficiency --- p.123
Chapter 5.10.2 --- Transmission electron microscopy (TEM) --- p.124
Chapter 5.11 --- Comparisons of three disinfection methods --- p.124
Chapter 6. --- Conclusions --- p.126
Chapter 7. --- References --- p.132
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42

"Visible-light-driven photocatalytic disinfection of bacteria by the natural sphalerite." Thesis, 2011. http://library.cuhk.edu.hk/record=b6075360.

Full text
Abstract:
Chen, Yanmin.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (leaves 140-160).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
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43

Alfa, Dorcas Enaji. "Evaluation of a small scale water disinfection system using WFMF." Thesis, 2017. http://hdl.handle.net/10321/2543.

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Abstract:
Submitted in fulfillment of the academic requirement for the degree Master of Engineering in Chemical Engineering, Department of Chemical Engineering, Faculty of Engineering and the Built Environment, Durban University of Technology, Durban, South Africa, 2017.
Provision of microbiologically safe drinking water for people living in the rural areas of developing countries remains a major challenge to date. One of the reasons is due to the inability to access potable water mainly because of poor existing water purification systems. Current measures have been put in place to address the challenges of rural water supply. Development of appropriate technologies such as decentralized water treatment supply in the form of point of use (POU) systems are been considered. In lieu of the above, an appropriate POU system known as the Remote Rural Water Treatment System (RRWTS) was developed at Durban University of Technology (DUT). The RRWTS is polyester based locally sourced Woven Fabric Microfiltration (WFMF) membrane system. The unit is made up of flat sheet modules that are assembled into a pack. It is a robust gravity driven system with the ability to remove suspended solids and colloids in the form of turbidity. The system has high flux of 35 ± 7 LMH and turbidity below 1 NTU, it has the ability to remove pathogens well above 95%. However, this does not comply with WHO and SANS drinking water standards of zero E. coli count/100 ml of treated water. In order to bring the water treated by RRWTS to a satisfactory level for drinking, it is then necessary to add a separate disinfection step like chlorination step to further remove the remaining microbial contaminants. Thus the main objective of the study was to evaluate the disinfection efficacy of two disinfectants namely waterguard and bromochlor tablet disinfectants and investigate their integration with the WFMF membrane. The study was categorised into three parts. The first part is the addition of disinfectants to unfiltered river water sources for the determination of residual chlorine and the most optimum dose that will yield effective disinfection and also evaluate the extent of E. coli removal by the disinfectants. The second stage was the filtration of four river water sources using the woven fibre membrane (WFM) to determine the efficiency of WFMF. Finally the effect of disinfection kinetics on disinfection was achieved by agitating the water after disinfection and allowing it to stand at different contact times. Performance of the RRWTS was determined by the amount of E. coli and turbidity removed during filtration using WFMF and by chemical disinfectants after filtration. The results on residual chlorine for different water sources showed that feed quality and disinfectant dose determines the quantity of residual chlorine on all the water sources. The effectiveness of chemical disinfectants in E. coli removal is affected by the quality of water to be disinfected. The study showed that turbidity plays a major role on disinfection by increasing chlorine demand on water sources with high turbidity levels. The WFMF demonstrated excellent filtration performance by producing permeates with turbidity less than 1 NTU for feed turbidities ranging from 10 to 200 NTU. The E. coli removal efficiency by WFMF was very high on all the water sources treated. There was 95-99.8% E. coli removal on raw feeds with influent E. coli ranging between 500 and 44500 CFU/100 ml. It was seen that major benefits are derived from integrating the WFMF (RRWTS) with chemical disinfection. The benefits includes; better disinfection that meets drinking water set guidelines of zero E. coli and improved quality of water. The need for disinfection kinetics in order to obtain superior disinfection was eliminated. The possibility of disinfection-by-product formation was reduced as smaller quantities of chemical disinfectants were required for complete disinfection on the filtered water.
M
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44

"Genetical and physiological studies of photocatalytic disinfection of Escherichia coli." 2012. http://library.cuhk.edu.hk/record=b5549496.

Full text
Abstract:
水資源缺乏引起的一系列問題在世界上已建得到廣泛關注，因此，確保提供潔淨衛生的水在保護人類健康和環境方面起著重要作用。近來，光催化作為頗有前景的替代方法被廣泛應用殺菌除污。二氧化鈦是目前研究最多應用最廣的光催化劑。基於紫外光譜照射，催化劑表面產生活性氧化物種，這些物種具有強氧化性能殺滅細胞。
本文首次研究了母體菌種大腸桿菌BW25113和它的同源單基因缺陷變異體對光催化殺菌的靈敏度差異。母體菌種和變異菌種表現出不同的耐受性。基於此，能幫助發掘出重要的變種。通過生物化學方法，可以檢測出不同菌種的生理性特徵。結合其他方法，可以進一步揭示光催化殺菌的生理性機理。
首先，我們篩選出了兩種重要的變異體。一種是大腸桿菌JW1081，即脂肪酸變異體，該菌種缺乏脂肪酸合成調節的關鍵基因。一種是大腸桿菌JW3942，即乙酰輔酶A變異體，該菌種缺乏乙酰輔酶A合成調控得到關鍵激酶。我們發現脂肪酸變異體對光催化處理的耐受性稍低，而乙酰輔酶A變異體則耐受性較高。 同時發現，溫度可以調節細胞膜的不飽和酸和飽和酸的比例。因此，我們提出脂肪酸和乙酰輔酶A是光催化殺菌中的重要影響因子。
更進一步研究發掘了細胞內酶和光催化產生的活性氧物種間的關係。大腸桿菌JW3914，即過氧化氫酶變異體，是發現的另一個重要的變異體。通過對母體和變異體的淬滅劑實驗，主要的殺菌活性氧物種是光催化產生的雙氧水，而不是羥基自由基。細胞體內的過氧化氫酶誘導在母體菌體內發現，而未在變異體內檢測到。
本課題採用母體/單基因變異體的研究方法，為全面深刻理解光催化殺菌的深層機理提供一種全新的研究思路。
Many problems associated with the lack of clean, fresh water worldwide are well known. Developing countries will particularly be affected by water availability problems and there will be further pressure on water demand resulting from economic development and population growth. Therefore, the provision of safe and clean water plays a key role in protecting human health and the environment. Recently, photocatalytic oxidation (PCO) has been widely accepted as a promising alternative method of water disinfection. Titanium dioxide (TiO₂) has been investigated extensively and is the most widely used photocatalyst. Upon the irradiation of UVA lamp, reactive charged and oxidative species are generated on TiO₂ surface and can inactive the bacterial cells.
In this study, the photocatalytic performances of a parental strain (E.coli BW25113) and its isogenic single-gene deletion mutant strains have been investigated for the first time. These bacterial strains exhibited different sensitivies towards photocalytic inactivation. Based on this, it can help reveal some important mechanism from the mutations. Biotic factors were confirmed by physiological biochemical measurement.
Firstly, we screened out the potential mutation fabF⁻ mutant (E. coli JW1081, carrying the mutation of fabF759(del)::kan) and coaA⁻ mutant (E. coli JW3942, carrying the mutation of coaA755(del)::kan). The isogenic fabF⁻ mutant is slightly more susceptible, and coaA⁻ mutant is less susceptible to photocatalytic inactivation. Through conditioning temperature, it adjusts the ratio of unsaturated to saturated fatty acid (FA) of cell membrane. We propose that FA profile and coenzyme A level significantly affect photocatalytic inactivation of bacteria. Moreover, we show photogenerated electrons (e⁻) can directly inactivate the cells of E. coli.
Furthermore, we report the relationship between the bacterial intracellular enzyme and the reactive charged and oxidative species (ROSs) generated during photocataltic inactivation. The katG⁻ mutant, E. coli JW3914, carrying the mutation of katG729(del)::kan is another important mutation. The parental and katG⁻ mutant strains reveal that photogenerated H₂O₂ but not OH[subscript free] is another important reactive oxygen species to inactivate bacteria. The inducible catalase (CAT) corresponding to H₂O₂can be detected in parental strain but not in katG⁻ mutant.
The research methodology using parental/single-gene deletion mutant strains is expected to shed light on fully understanding of the fundamental mechanism of photocatalytic inactivation of E. coli.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Gao, Minghui.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 130-177).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
Acknowledgements --- p.i
Abstract --- p.v
Table of contents --- p.ix
List of Figures --- p.xiii
List of Plates --- p.xvii
List of Tables --- p.xviii
List of Equations --- p.xix
Abbreviations --- p.xxi
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Water crisis --- p.1
Chapter 1.2 --- Traditional disinfection methods --- p.3
Chapter 1.2.1 --- Chlorination --- p.4
Chapter 1.2.2 --- Ozonation --- p.6
Chapter 1.2.3 --- Ultraviolet irradiation --- p.8
Chapter 1.2.4 --- Multiple disinfectants --- p.10
Chapter 1.3 --- Advanced oxidation process (AOPs) --- p.10
Chapter 1.3.1 --- Hydrogen Peroxide/Ozone (H₂O₂/O₃) --- p.11
Chapter 1.3.2 --- Ozone/Ultraviolet Irradiation (O₃/UV) --- p.12
Chapter 1.3.3 --- Hydrogen Peroxide/ Ultraviolet Irradiation (H₂O₂/UV) --- p.12
Chapter 1.3.4 --- Fenton's --- p.Reaction
Chapter 1.4 --- Solar photocatalytic disinfection (SPC-DIS) --- p.14
Chapter 1.4.1 --- Photocatalyst-TiO₂ --- p.31
Chapter 1.4.2 --- Irradiation sources --- p.35
Chapter 1.4.3 --- TiO₂ photocatalytic process --- p.35
Chapter 1.4.4 --- The role of photogenerated reactive charged and oxidative species (ROSs) --- p.38
Chapter 1.5 --- Bacteria --- p.40
Chapter 1.5.1 --- E. coli BW25113 --- p.40
Chapter 1.5.2 --- E. coli Keio Collection --- p.41
Chapter 1.5.3 --- Bacterial defense mechanism towards oxidative stresses --- p.44
Chapter 1.6 --- Photocalytic applications --- p.53
Chapter 1.7 --- Significance of the project --- p.55
Chapter 2. --- Objectives --- p.58
Chapter 3. --- Genetic studies of the roles of fatty acid and coenzyme A in photocatalytic inactivation of Escherichia coli --- p.61
Chapter 3.1 --- Introduction --- p.61
Chapter 3.2 --- Materials and methods --- p.65
Chapter 3.2.1 --- Photocatalyst --- p.65
Chapter 3.2.2 --- Bacterial nutrient --- p.66
Chapter 3.2.3 --- Bacterial strains --- p.67
Chapter 3.2.4 --- Photocatalytic inactivation --- p.69
Chapter 3.2.5 --- Fatty acid profile --- p.72
Chapter 3.2.6 --- Fluorescent measurement of bacterial coenzyme A content --- p.74
Chapter 3.2.7 --- The role of photogenerated electrons (e⁻) to bacterial inactivation --- p.74
Chapter 3.2.8 --- Transmission Electron Microscopic (TEM) --- p.75
Chapter 3.2.9 --- Photoelectrochemical measurement --- p.77
Chapter 3.3 --- Results --- p.77
Chapter 3.3.1 --- Photocatalytic inactivation --- p.77
Chapter 3.3.2 --- Effects of pre-incubation at different temperatures --- p.80
Chapter 3.3.3 --- Fatty acid profile --- p.83
Chapter 3.3.4 --- Fluorescent measurement of bacterial coenzyme A content --- p.84
Chapter 3.3.5 --- The role of electron (e⁻) in photocataytic inactivation --- p.84
Chapter 3.3.6 --- Transmission electron microscopy (TEM) --- p.89
Chapter 3.3.7 --- Photocurrent measurement --- p.90
Chapter 3.4 --- Discussion --- p.90
Chapter 3.5 --- Conclusions --- p.96
Chapter 4 --- Genetic and physiological studies of the role of Catalase and H₂O₂ in photocatalytic inactivation of E. coli --- p.98
Chapter 4.1 --- Introduction --- p.98
Chapter 4.2 --- Materials and methods --- p.101
Chapter 4.2.1 --- Bacterial strains --- p.101
Chapter 4.2.2 --- Photocatalytic performance --- p.102
Chapter 4.2.3 --- Scavenger studies --- p.103
Chapter 4.2.4 --- Effects of different pHs on photocatalytic inactivation --- p.104
Chapter 4.2.5 --- Measurement of bacterial catalase activity and H₂O₂ --- p.104
Chapter 4.2.6 --- Transmission electron microscopy (TEM) --- p.105
Chapter 4.2.7 --- Atomic absorption spectrophotometer (AAS) --- p.105
Chapter 4.3 --- Results and discussion --- p.106
Chapter 4.3.1 --- Photocatalytic performance --- p.106
Chapter 4.3.2 --- Scavenger studies --- p.108
Chapter 4.3.3 --- Contribution of hydrogen peroxide (H₂O₂) --- p.111
Chapter 4.3.4 --- Effects of different pHs on photocatalytic inactivation --- p.114
Chapter 4.3.5 --- Bacterial catalase (CAT) activity --- p.116
Chapter 4.3.6 --- Destruction model of bacterial cells --- p.118
Chapter 4.4 --- Conclusions --- p.120
Chapter 5. --- General conclusions --- p.122
Chapter 6. --- Prospectives --- p.125
Chapter 7. --- Appendix --- p.127
Chapter 8. --- References --- p.130
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45

"Disinfection of Legionella pneumophila by photocatalytic oxidation." 2005. http://library.cuhk.edu.hk/record=b5892344.

Full text
Abstract:
Cheng Yee Wan.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.
Includes bibliographical references (leaves 95-112).
Abstracts in English and Chinese.
Acknowledgements --- p.i
Abstract --- p.ii
Table of Contents --- p.vi
List of Figures --- p.xi
List of Plates --- p.xiv
List of Tables --- p.xvi
Abbreviations --- p.xviii
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Legionella pneumophila --- p.1
Chapter 1.1.1 --- Bacterial morphology and ultrastructure --- p.2
Chapter 1.1.2 --- Microbial ecology and natural habitats --- p.4
Chapter 1.1.2.1 --- Association with amoeba --- p.5
Chapter 1.1.2.2 --- Association with biofilm --- p.5
Chapter 1.2 --- Legionnaires' disease and clinical significance --- p.6
Chapter 1.2.1 --- Epidemiology --- p.6
Chapter 1.2.1.1 --- Worldwide distribution --- p.6
Chapter 1.2.1.2 --- Local situation --- p.7
Chapter 1.2.2 --- Clinical presentation --- p.7
Chapter 1.2.3 --- Route of infection and pathogenesis --- p.8
Chapter 1.2.4 --- Diagnosis --- p.10
Chapter 1.2.4.1 --- Culture of Legionella --- p.10
Chapter 1.2.4.2 --- Direct fluorescent antibody (DFA) staining --- p.13
Chapter 1.2.4.3 --- Serologic tests --- p.13
Chapter 1.2.4.4 --- Urine antigen testing --- p.14
Chapter 1.2.4.5 --- Detection of Legionella nucleic acid --- p.15
Chapter 1.2.5 --- Risk factors --- p.15
Chapter 1.2.6 --- Treatment for Legionella infection --- p.16
Chapter 1.3 --- Detection of Legionella in environment --- p.16
Chapter 1.4 --- Disinfection methods --- p.17
Chapter 1.4.1 --- Physical methods --- p.19
Chapter 1.4.1.1 --- Filtration --- p.19
Chapter 1.4.1.2 --- UV-C irradiation --- p.20
Chapter 1.4.1.3 --- Thermal eradication (superheat-and-flush) --- p.21
Chapter 1.4.2 --- Chemical methods --- p.21
Chapter 1.4.2.1 --- Chlorination --- p.21
Chapter 1.4.2.2 --- Copper-silver ionization --- p.22
Chapter 1.4.3 --- Effect of biofilm and other factors on disinfection --- p.23
Chapter 1.5 --- Photocatalytic oxidation (PCO) --- p.24
Chapter 1.5.1 --- Generation of strong oxidants --- p.24
Chapter 1.5.2 --- Disinfection mechanism(s) --- p.27
Chapter 1.5.3 --- Major factors affecting the process --- p.28
Chapter 2. --- Objectives --- p.30
Chapter 3. --- Materials and Methods --- p.31
Chapter 3.1 --- Chemicals --- p.31
Chapter 3.2 --- Bacterial strains and culture --- p.31
Chapter 3.3 --- Photocatalytic reactor --- p.33
Chapter 3.4 --- PCO efficacy tests --- p.33
Chapter 3.5 --- PCO sensitivity tests --- p.35
Chapter 3.6 --- Optimisation of PCO conditions --- p.35
Chapter 3.6.1 --- Optimization of TiO2 concentration --- p.36
Chapter 3.6.2 --- Optimization of UV intensity --- p.36
Chapter 3.6.3 --- Optimization of depth of reaction mixture --- p.36
Chapter 3.6.4 --- Optimization of stirring rate --- p.37
Chapter 3.6.5 --- Optimization of initial pH --- p.37
Chapter 3.6.6 --- Optimization of treatment time and initial cell concentration --- p.37
Chapter 3.6.7 --- Combinational optimization --- p.37
Chapter 3.7 --- Transmission electron microscopy (TEM) --- p.38
Chapter 3.8 --- Fatty acid profile analysis --- p.40
Chapter 3.9 --- Total organic carbon (TOC) analysis --- p.42
Chapter 3.10 --- UV-C irradiation --- p.44
Chapter 3.11 --- Hyperchlorination --- p.44
Chapter 3.12 --- Statistical analysis and replication --- p.45
Chapter 3.13 --- Safety precautions --- p.45
Chapter 4. --- Results --- p.46
Chapter 4.1 --- Efficacy test --- p.46
Chapter 4.2 --- PCO sensitivity --- p.47
Chapter 4.3 --- Optimization of PCO conditions --- p.48
Chapter 4.3.1 --- TiO2 concentration --- p.48
Chapter 4.3.2 --- UV intensity --- p.48
Chapter 4.3.3 --- Depth of reaction mixture --- p.51
Chapter 4.3.4 --- Stirring rate --- p.56
Chapter 4.3.5 --- Effect of initial pH --- p.56
Chapter 4.3.6 --- Effect of treatment time and initial concentrations --- p.56
Chapter 4.3.7 --- Combinational effects --- p.63
Chapter 4.4 --- Transmission electron microscopy (TEM) --- p.66
Chapter 4.4.1 --- Morphological changes induced by PCO --- p.66
Chapter 4.4.2 --- Comparisons with changes caused by UV-C irradiation and chlorination --- p.67
Chapter 4.5 --- Fatty acid profile analysis --- p.71
Chapter 4.6 --- Total organic carbon (TOC) analysis --- p.73
Chapter 4.7 --- UV-C irradiation --- p.74
Chapter 4.8 --- Hyperchlorination --- p.74
Chapter 5. --- Discussion --- p.76
Chapter 5.1 --- Efficacy test --- p.76
Chapter 5.2 --- PCO sensitivity --- p.76
Chapter 5.3 --- Optimization of PCO conditions --- p.77
Chapter 5.3.1 --- Effect of TiO2 concentration --- p.77
Chapter 5.3.2 --- Effect of UV intensity --- p.78
Chapter 5.3.3 --- Effect of depth of reaction mixture --- p.79
Chapter 5.3.4 --- Effect of stirring rate --- p.79
Chapter 5.3.5 --- Effect of initial pH --- p.80
Chapter 5.3.6 --- Effect of treatment time and initial concentrations --- p.81
Chapter 5.3.7 --- Combinational effect --- p.82
Chapter 5.4 --- Transmission electron microscopy (TEM) --- p.83
Chapter 5.4.1 --- Morphological changes induced by PCO --- p.83
Chapter 5.4.2 --- Comparisons with changes caused by UV-C irradiation and chlorination --- p.85
Chapter 5.5 --- Fatty acid profile analysis --- p.85
Chapter 5.6 --- Total organic carbon (TOC) analysis --- p.86
Chapter 5.7 --- Comparisons of the three disinfection methods --- p.88
Chapter 6. --- Conclusion --- p.91
Chapter 7. --- References --- p.95
Chapter 8. --- Appendix --- p.113
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46

Amos, Steve A. "Ultraviolet disinfection kinetics for potable water production." 2008. http://hdl.handle.net/2440/50044.

Full text
Abstract:
Irradiation with ultraviolet (UV) light is used for the disinfection of bacterial contaminants in the production of potable water, and in the treatment of selected wastewaters. However, efficacy of UV disinfection is limited by the combined effect of suspended solids concentration and UV absorbance. Limited published UV disinfection data are available that account for the combined effects of UV dose, suspended solids concentration and UV absorbance. This present lack of a rigorous quantitative understanding of the kinetics of UV disinfection limits process optimisation and wider application of UV treatment. The development and validation of an adequate model to describe UV disinfection kinetics presented in this thesis can therefore be justified by an increased confidence of reliability of design for UV disinfection. Using the published data of Nguyen (1999), four established model forms were assessed to account for the combined effect of suspended solids and/or soluble UV absorbing compounds, and UV dose on the efficacy of disinfection. The four model forms were: a log-linear form, Davey Linear-Arrhenius (DL-A), Square-Root (or Ratkowsky- Belehradek) and a general nth order Polynomial (nOP) form that was limited to a third order. Criteria for assessment of an adequate predictive model were established including: accuracy of predicted against observed values, percent variance accounted for (%V), and; appraisal of residuals. The DL-A model was shown to best fit the data for UV disinfection of Escherichia coli (ATCC 25922); followed by the nOP, log-linear and Square-Root forms. However, the DL-A form must be used in conjunction with a first-order chemical reaction equation, and was shown to predict poorly at high experimental values of UV dose (> 40,000 μWs cm-2). The DL-A model was not amenable to extrapolation beyond the observed UV dose range. To overcome the shortcomings of the Davey Linear-Arrhenius model synthesis of two new, non-linear model forms was undertaken. The two models were a modified exponentially damped polynomial (EDPm) and a form based on the Weibull probability distribution. The EDPm model has three terms: a rate coefficient (k), a damping coefficient (λ), and; a breakpoint dose ([dose]B). The rate coefficient governs the initial rate of disinfection prior to the onset of tailing, whilst the breakpoint is the UV dose that indicates the onset of tailing. The damping coefficient controls curvature in the survivor curve. The Weibull model has just two terms: a dimensionless scale parameter (β0), and; a shape parameter (β1). The scale parameter represents the level of disinfection in the tail of the survivor curve (as log10 N/N0), whilst the shape parameter governs the degree of curvature of the survivor data. Each model was assessed against the independent and published UV disinfection data of Nelson (2000) for treatment of faecal coliforms in a range of waste stabilisation pond effluents. Both models were found to be well suited to account for tailing in these UV disinfection data. Overall, the EDPm model gave a better fit to the data than the Weibull model form. To rigorously validate the suitability of the new EDPm and Weibull models a series of experimental trials were designed and carried out in a small-scale pilot UV disinfection unit. These trials included data determined specifically at low values of UV dose (<10,000 μWs cm-2) to fill the gap in the experimental data of Nguyen (1999). The experimental trials were carried out using a commercially available, UV disinfection unit (LC5TM from Ultraviolet Technology of Australasia Pty Ltd). Purified water contaminated with Escherichia coli (ATCC 25922) with a range of feed water flow rates (1 to 4 L min-1) was used. E. coli was selected because it is found in sewage, or water contaminated with faecal material, and is used as an indicator for the presence of enteric pathogens. E. coli should not be present in potable water. The hydrodynamics of water flow within the disinfection unit were established using digital video photography of dye trace studies with Methylene Blue. Nominal UV dose (2,700 to 44,200 μWs cm-2) was controlled by manipulating the flow rate of feed water through the UV disinfection unit (i.e. residence time), or by varying the exposed length of the control volume of the disinfection unit. The transmittance of the feed water (at 254 nm) was adjusted by the addition of either a soluble UV absorbing agent (International RoastTM instant coffee powder; 0.001 to 0.07 g L-1), or by addition of suspended matter as diatomaceous earth (Celite 503TM; 0.1 to 0.7 g L-1, with a median particle size of 23 μm). The absorbing agent (instant coffee), when in a comparable concentration, was found to produce a greater reduction in water transmission than the suspended material (Celite 503TM). It therefore contributed to a greater reduction in the initial rate of disinfection. Neither agent was found to produce a systematic reduction in the observed efficacy of disinfection however. Experimental results highlight that in the absence of soluble absorbing agents, or suspended solids, the initial rate of disinfection is higher when fewer viable bacteria are initially present. Both the new EDPm and Weibull forms gave a good fit to the experimental data. The EDPm better fitted the data on the basis of residual sum-of-squares (0.03 to 2.13 for EDPm cf. 0.16 to 4.37 for the Weibull form). These models are both of a form suitable for practical use in modelling UV disinfection data. Results of this research highlight the impact of water quality, as influenced by the combined effect of UV dose, suspended solids concentration and UV absorbance, on small-scale UV disinfection for potable water production. Importantly, results show that the concentration of soluble UV absorbing agents and suspended solids are not in themselves sufficient criteria on which to base assessment of efficacy of UV disinfection
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342403
Thesis (M.Eng.Sc.) - University of Adelaide, School of Chemical Engineering, 2008
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47

Amos, Steve A. "Ultraviolet disinfection kinetics for potable water production." Thesis, 2008. http://hdl.handle.net/2440/50044.

Full text
Abstract:
Irradiation with ultraviolet (UV) light is used for the disinfection of bacterial contaminants in the production of potable water, and in the treatment of selected wastewaters. However, efficacy of UV disinfection is limited by the combined effect of suspended solids concentration and UV absorbance. Limited published UV disinfection data are available that account for the combined effects of UV dose, suspended solids concentration and UV absorbance. This present lack of a rigorous quantitative understanding of the kinetics of UV disinfection limits process optimisation and wider application of UV treatment. The development and validation of an adequate model to describe UV disinfection kinetics presented in this thesis can therefore be justified by an increased confidence of reliability of design for UV disinfection. Using the published data of Nguyen (1999), four established model forms were assessed to account for the combined effect of suspended solids and/or soluble UV absorbing compounds, and UV dose on the efficacy of disinfection. The four model forms were: a log-linear form, Davey Linear-Arrhenius (DL-A), Square-Root (or Ratkowsky- Belehradek) and a general nth order Polynomial (nOP) form that was limited to a third order. Criteria for assessment of an adequate predictive model were established including: accuracy of predicted against observed values, percent variance accounted for (%V), and; appraisal of residuals. The DL-A model was shown to best fit the data for UV disinfection of Escherichia coli (ATCC 25922); followed by the nOP, log-linear and Square-Root forms. However, the DL-A form must be used in conjunction with a first-order chemical reaction equation, and was shown to predict poorly at high experimental values of UV dose (> 40,000 μWs cm-2). The DL-A model was not amenable to extrapolation beyond the observed UV dose range. To overcome the shortcomings of the Davey Linear-Arrhenius model synthesis of two new, non-linear model forms was undertaken. The two models were a modified exponentially damped polynomial (EDPm) and a form based on the Weibull probability distribution. The EDPm model has three terms: a rate coefficient (k), a damping coefficient (λ), and; a breakpoint dose ([dose]B). The rate coefficient governs the initial rate of disinfection prior to the onset of tailing, whilst the breakpoint is the UV dose that indicates the onset of tailing. The damping coefficient controls curvature in the survivor curve. The Weibull model has just two terms: a dimensionless scale parameter (β0), and; a shape parameter (β1). The scale parameter represents the level of disinfection in the tail of the survivor curve (as log10 N/N0), whilst the shape parameter governs the degree of curvature of the survivor data. Each model was assessed against the independent and published UV disinfection data of Nelson (2000) for treatment of faecal coliforms in a range of waste stabilisation pond effluents. Both models were found to be well suited to account for tailing in these UV disinfection data. Overall, the EDPm model gave a better fit to the data than the Weibull model form. To rigorously validate the suitability of the new EDPm and Weibull models a series of experimental trials were designed and carried out in a small-scale pilot UV disinfection unit. These trials included data determined specifically at low values of UV dose (<10,000 μWs cm-2) to fill the gap in the experimental data of Nguyen (1999). The experimental trials were carried out using a commercially available, UV disinfection unit (LC5TM from Ultraviolet Technology of Australasia Pty Ltd). Purified water contaminated with Escherichia coli (ATCC 25922) with a range of feed water flow rates (1 to 4 L min-1) was used. E. coli was selected because it is found in sewage, or water contaminated with faecal material, and is used as an indicator for the presence of enteric pathogens. E. coli should not be present in potable water. The hydrodynamics of water flow within the disinfection unit were established using digital video photography of dye trace studies with Methylene Blue. Nominal UV dose (2,700 to 44,200 μWs cm-2) was controlled by manipulating the flow rate of feed water through the UV disinfection unit (i.e. residence time), or by varying the exposed length of the control volume of the disinfection unit. The transmittance of the feed water (at 254 nm) was adjusted by the addition of either a soluble UV absorbing agent (International RoastTM instant coffee powder; 0.001 to 0.07 g L-1), or by addition of suspended matter as diatomaceous earth (Celite 503TM; 0.1 to 0.7 g L-1, with a median particle size of 23 μm). The absorbing agent (instant coffee), when in a comparable concentration, was found to produce a greater reduction in water transmission than the suspended material (Celite 503TM). It therefore contributed to a greater reduction in the initial rate of disinfection. Neither agent was found to produce a systematic reduction in the observed efficacy of disinfection however. Experimental results highlight that in the absence of soluble absorbing agents, or suspended solids, the initial rate of disinfection is higher when fewer viable bacteria are initially present. Both the new EDPm and Weibull forms gave a good fit to the experimental data. The EDPm better fitted the data on the basis of residual sum-of-squares (0.03 to 2.13 for EDPm cf. 0.16 to 4.37 for the Weibull form). These models are both of a form suitable for practical use in modelling UV disinfection data. Results of this research highlight the impact of water quality, as influenced by the combined effect of UV dose, suspended solids concentration and UV absorbance, on small-scale UV disinfection for potable water production. Importantly, results show that the concentration of soluble UV absorbing agents and suspended solids are not in themselves sufficient criteria on which to base assessment of efficacy of UV disinfection
Thesis (M.Eng.Sc.) - University of Adelaide, School of Chemical Engineering, 2008
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48

"Investigation of turbidity and chlorine disinfection in South African waters." Thesis, 2010. http://hdl.handle.net/10413/1433.

Full text
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49

Chong, Meng Nan. "Nano-photocatalytic mineralization and disinfection for water reclamation: from catalyst engineering to process optimization and modelling." Thesis, 2010. http://hdl.handle.net/2440/63156.

Full text
Abstract:
In this thesis, a feasible photocatalytic technology for water treatment was explored using a bottom-up approach in four separate research and developmental stages. These include (1) the synthesis, characterizations and photocatalytic activity (PCI) evaluation of a thin nanocrystals layer of titanium dioxide (TiO₂) immobilised onto modified mesoporous kaolin clay; (2) optimization and kinetics study of the photocatalytic reaction with recalcitrant organic dye Congo red (CR); (3) optimization and kinetics study of the photocatalytic disinfection with surrogate Escherichia coli and (4) assessment of a sequential batch reactor (SBR) mode for semi-continuous removal of dissolved pharmaceutical organic matters from secondary municipal wastewater. A modified two step sol-gel approach was used to immobilise layered of TiO₂ nanocrystals onto structurally stable kaolin (TiO₂-K) particles for enhanced physical properties. The TiO₂-K demonstrated a superior settling ability, adsorption capacity, PCI and stability compared to other conventional TiO₂ particles. Microscopic characterizations revealed that the modified kaolin provides a delaminated sandwich silica structure which minimizes chemical intercalation and further promotes high external surface area for heterocoagulation with microporous TiO₂ nanocrystals. Thermal regeneration cycles for the photocatalysts lifespan study examines that the PCI of TiO₂-K was improved over six treatment cycles, as a result of the change in average TiO₂ nanocrystals size and porosity. The real operational performances of the TiO₂-K photocatalysts for the organic degradation in water were investigated in a self-designed laboratory scale annular slurry photoreactor (ASP) system. The effect of key operational factors for the ASP system, such as TiO₂-K loading, pH, aeration rate and CR concentration were investigated. Results show that pH was the most significant factor that affects the adsorption and photocatalytic reactions in the ASP system. The point of zero charge (PZC) for the TiO₂-K particles was found to shift towards more basic extent of 9.5, resulting in a detrimental PCI when the ASP was operated at pH > PZC (TiO₂-K). The optimum operating conditions of the ASP was found to be 6.0 g L⁻¹ TiO₂-K loading, pH 7.0, 7.5 L min⁻¹ aeration rate and 40 mg L⁻¹ CR concentration. Under these optimum ASP conditions, the CR was completely photo-degraded in 4 h along with 80% reduction in chemical oxygen demand (COD) of the LC/MS-identified intermediates species. Owing to the lack of understanding and predictive in the singular optimum ASP condition, the Taguchi method was employed to collectively optimise the operating factor; determine the synergistic factor interactions and key influential factors, and further develop an empirical response surface model for the PCI prediction. From the Taguchi experiments, the photo-oxidation kinetics of CR exhibited saturation kinetics and thus, the Langmuir-Hinshelwood (L-H) model was applied. The Taguchi method predicted the optimum L-H apparent first order rate constant of 3.46 x 10⁻² min⁻¹ under the ASP operating conditions of 8.0 g L⁻¹ TiO₂-K, pH 5.0, 7.5 L min⁻¹ aeration rate and 40 mg L⁻¹ CR. Analysis of variance revealed that the CR concentration is the most significant factor, while pH appears to be the least significant one. The aeration rate in ASP was determined to have a significant synergistic effect on the TiO₂-K loading from the 3-D response surface plot. When the photo-oxidation of CR was referenced to the anatase titanate nanofiber (TNC) with PZC of 4.6, it was observed that the ASP operation was constrained by a narrow functional pH range. The optimum ASP operating conditions with slurry TNC were 4.0 g L⁻¹ TNC loading, pH 3.0, 5 L min⁻¹ aeration rate and 60 mg L⁻¹ CR, resulting in a degradation rate of 3.47 x 10⁻² mol L⁻¹ min⁻¹. Subsequent Taguchi analysis found that the low PZC (TNC) has a profound effect on the synergistic interaction with its loading concentrations. The 3D response plots showed that the low PZC (TNC) could be compensated with a high TNC loading at pH >PZC (TNC) and low aeration rate for optimal conditions. The Taguchi method predicted that the optimum ASP operating conditions were 6.0 g L⁻¹ TNC, pH 9, 5.0 L min⁻¹ aeration rate and 20 mg L⁻¹ CR. Analysis of variance shows that the pH, aeration rate and CR concentration were the significant factors, while TNC loading is the least significant one. The PCI for both photocatalysts were also tested against the photo-disinfection of Escherichia coli (ATCC 11775) as the surrogate indicator in the batch ASP system. In both investigations, the photocatalytic inactivation kinetics was found to exhibit non-linearity in the enumerated bacteria against irradiation time. The modified Hom model was used to fit a sigmoidal-shape bacterial survivor curve with strong shoulder and tailing characteristics. Using the TNC, the dissolved oxygen level in the open ASP system was found to be constantly replenished and further affects the photocatalytic inactivation kinetics. An L-H mechanistic model was proposed to determine oxygen transfer limitation in the photocatalytic disinfection process at different TNC loadings. A Fe²⁺ up to 1.0 mg L⁻¹ could initiate the residual disinfecting effect (RDE) of the photocatalytic reaction in the ASP, with constant dissociation of hydrogen peroxide (H₂O₂) to hydroxyl radicals (OH•). The RDE was diminished with increasing COD values. To effectively suppress the bacterial regrowth, the dissolved organic carbon should be well suppressed below 16 mg COD L⁻¹. Finally, the ASP system was operated as a SBR mode to allow semi-continuous treatment of the secondary municipal wastewater spiked with pharmaceutical Carbamazepine (CBZ) compound. A microfiltration module of 0.2 μm in porosity was fitted parallel to the reactor light source. The effects of key factors such as SBR cycles, nitrate (NO₃⁻), phosphate (PO₄³⁻), COD and photocatalysts on the effective photocatalytic CBZ removal were investigated. When the CBZ was degraded in the presence of high molecular weight effluent organic matter (EOM) in wastewater, the photocatalytic reaction appeared to have a preferential attack on the EOM that subsequently lower the degradation efficiency of CBZ. Other than this, the PO₄³⁻ in the wastewater showed a detrimental effect of photocatalyst fouling and deactivation on both TiO₂ catalysts used, resulting in a strong catalyst deactivation, and fouling of the catalysts. The deactivation and fouling are site specific and do not completely retard the photoactivity of the catalysts used. The sequential batch-annular slurry photoreactor (SB-ASP) was effectively operated up to two SBR cycles at catalyst loading (1 gL⁻¹) without any photocatalyst replacement, as the semi-continuous operation allows simultaneous water discharge and UV photocatalyst reactivation phase.
Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2010
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"Synthesis, characterization and assessment of nanocomposites-based ultrafiltration membrane with reduced fouling and better wastewater disinfection." Thesis, 2015. http://hdl.handle.net/10210/13702.

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Ph.D. (Chemistry)
This study addressed the incorporation of nanotechnology-based materials, either through incorporating nanomaterials or by introducing nanostructures onto the membrane matrix, to form nano-enabled polymeric membranes with high specific flux and better anti-fouling profile. The aim of the study was to integrate nanotechnology and membrane science in order to improve the performance of water filtration membranes by alleviating some of the specific shortcomings of water treatment membranes......
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