Dissertations / Theses: 'Disinfection'

1

Black, S. H. "Disinfection by-product formation from swimming pool water disinfection." Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284924.

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Winward, Gideon Paul. "Disinfection of grey water." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/2894.

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The reuse of grey water, for applications such as toilet flushing and irrigation, represents a potential sustainable solution to water shortages experienced by regions worldwide. Although reused grey water is not intended for potable use, the potential for transmission of waterborne pathogens by aerosol inhalation, topical contact, or indirect ingestion is a key concern for grey water reuse. This thesis explores the pathogen content of grey water and investigates pathogen removal through treatment and disinfection processes. The impacts of organic and particulate material in grey water on the efficacy of disinfection processes are investigated in depth. Grey water can potentially harbour a range of pathogenic microorganisms, with opportunistic bacterial pathogens in grey water indicating a particular risk of grey water reuse for the vulnerable members of society. The disinfection of grey water is therefore critical prior to reuse. Particulate material in grey water limits the efficacy of disinfection by chlorine, ultraviolet light, and origanum essential oil, by shielding microorganisms from the applied disinfectant. Microbial resistance to the disinfectants was linked to the particle size distribution of the grey water, with increasing particle size offering greater protection to associated microorganisms. Additional organic material was shown to reduce the applied disinfectant but no impact on microorganism resistance to disinfection was observed when a constant disinfectant dose was maintained. Treatment of grey water, targeting the removal of large particulate material, improves the efficacy of grey water disinfection, allowing compliance with stringent microbiological standards for urban water reuse.

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3

Gallagher, Theresa Bernadette. "Application of photoactivated disinfection." Thesis, University of Brighton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511582.

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Fang, Qian. "Chloride-assisted electrochemical disinfection : bacteria and bacteriophage inactivation and disinfection by-product formation /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202004%20FANG.

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Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 111-124). Also available in electronic version. Access restricted to campus users.

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5

Demitry, Mariana. "Evaluating Water Filtration and Disinfection for Household, Using Slow Sand Filters plus Solar Disinfection." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/6911.

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In this research, a household water treatment system was built and evaluated as a trial for improving the drinking water quality of the Nile River for the low-income communities. The system consisted of household-scale slow sand filters, and transparent polyethylene terephthalate-bottles for solar disinfection. The evaluation of the system depended on the removal/inactivation of some surrogates for the reference pathogens, and turbidity. The reference pathogens are pathogens specified by the World Health Organization to evaluate the efficiency of the household water treatment options. They were chosen to represent the classes of pathogens in water (bacteria, viruses, protozoa). The surrogates used in the evaluation of the system are Escherichia coli (E.coli), Clostridium perfringens and Escherichia coli bacteriophage (MS2). The candidate surrogates are also specified by the World Health Organization. The designed household-scale slow sand filter was very efficient in removing the different turbidity levels to ≤0.4NTU. The evaluated system is classified as highly protective because it was able to achieve higher than 4 log removal for E.coli and Clostridium perfringens, and higher than 5 log removal for MS2.

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6

Ye, Zhengcai. "UV Disinfection between Concentric Cylinders." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14641.

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Outbreaks of food-born illness associated with the consumption of unpasteurized juice and apple cider have resulted in a rule published by the U.S. Food and Drug Administration (FDA) in order to improve the safety of juice products. The rule (21 CFR120) requires manufacturers of juice products to develop a Hazard Analysis and Critical Control Point (HACCP) plan and to achieve a 5-log reduction in the number of the most resistant pathogens. Ultraviolet (UV) disinfection is one of the promising methods to reach this 5-log reduction of pathogens. The absorption coefficients of juices typically vary from 10 to 40 1/cm and can be even higher depending on brand and processing conditions. Thin film reactors consisting of two concentric cylinders are suitable for inactivating pathogens in juices. When the two concentric cylinders are fixed, the flow pattern in the gap can be laminar Poiseuille flow or turbulent flow depending on flow rates. If the inner cylinder is rotating, and the rotating speed of the inner cylinder exceeds a certain value, the flow pattern can be either laminar or turbulent Taylor-Couette flow. UV disinfection between concentric cylinders in laminar Poiseuille flow, turbulent flow and both laminar and turbulent Taylor-Couette flow was investigated experimentally and numerically. This is the first systematic study done on UV disinfection between concentric cylinders in all three flow patterns. The present work provides new experimental data for pathogen inactivation in each of the three flow patterns. In addition, the present study constitutes the first systematic numerical CFD predictions of expected inactivation levels. Proper operating parameters and optimum gap widths for different flow patterns are suggested. It is concluded that laminar Poiseuille flow provides inferior (small) inactivation levels while laminar Taylor-Couette flow provides superior (large) inactivation levels. The relative inactivation levels are: laminar Poiseuille flow < turbulent flow < laminar Taylor-Couette flow.

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7

Bullock, Gillian. "Disinfection of swimming pool water." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/108.

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Results from this study, which has investigated the impact of the treatment technologies of chlorination, ozonation and UV irradiation on pool water quality are reported. The aim of the study was to evaluate the effect of these technologies in an unbiased way using a unique protocol, and to calculate a mass balance across the pool system. Data refer to a protocol based on operation of a 2.2m (cubed) capacity pilot swimming pool, which allows the comparison of technologies applied with reference to the propensity to generate the chlorinated disinfection by-products (DBPs) of chloramines and trihalomethanes (THMs). The protocol makes use of a specially developed body fluid analogue (BFA), containing simulant endogenous organic matter, with a soiling analogue consisting of commercial humic acid (HA). Using this analogue, levels of organic carbon (OC) and chloramines similar to those recorded in real pools have been obtained, along with somewhat lower levels of THMs. Results revealed conventional chlorination leads to steady-state TOC and DBP levels following an equilibrium period of 200-600 hours, with concentration values which are dependent on BFA loading rate. Following equilibration nitrate is the only DBP accumulating in the pool water, accounting for between 4% and 28% of the ammoniacal nitrogen loaded into the pool depending upon the operating conditions (primarily the Cl:N ratio). Both UV irradiation and ozonation, the latter combined with downstream adsorption, provide a similar efficacy in reducing chloramine levels, with their effect on THM and nitrate formation being highly dependent on the pH level and chlorine dose rate. This study builds on previous experimentation by including a more rigorous analysis of ozone-GAC with respect to DBP formation, a unique analysis of UV irradiation and a more comprehensive mass balance calculation of C, Cl and N across the pool. The study has established that no accumulation of carbon takes place in the pool, contrary to postulations made in previous published studies, and that the balance between the chloramines and THM DBPs is significantly affected by the HA loading.

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Alrousan, Dheaya. "Solar Photocatalytic Disinfection of Water." Thesis, University of Ulster, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493903.

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9

梁啟承 and Kai-shing Alex Leung. "Control of disinfection by-products." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41549429.

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McCraven, Elizabeth Kathleen. "Electro-disinfection of Ballast Water." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/1095.

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This research validates electro-disinfection as a potential secondary ballast water treatment technology. Electricity applied to bacteria laden water produced bactericidal effects, reactive oxygen species and chlorine generation which annihilated bacteria. Evaluation of electro-disinfection experiments showed titanium electrodes had the maximum kill efficacy while disinfection with aluminum and stainless steel electrodes had lesser kill efficacy. A continuous flow electro-disinfection reactor was evaluated utilizing artificial brackish and fresh ballast water. Brackish water had a 100% bacteria kill efficiency utilizing titanium electrodes at a current density of 10 mA/cm2. Fresh water was augmented with the addition of salt to increase its electrical conductivity from 232 μS/cm to 873 μS/cm to ascertain 100% bacteria kill efficiency with titanium electrodes and a current density of 9.8 mA/cm2.

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Blazo, Christopher. "Wastewater Disinfection with HYDROFLOW Technology." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1611.

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Disinfection is the final and very important step of wastewater treatment to maintain healthy ecosystems. Although chlorination is the most prevalent wastewater disinfection method, there are serious safety concerns and ecological problems associated with its use. The purpose of this study was to test the feasibility of using a HydroFLOW 60i unit for wastewater disinfection, as an alternative to chlorination. The study was performed using two different reactors, namely, a bench-scale laboratory batch reactor, and a continuous flow, pilot unit. Using the batch reactor, it was found out that the HydroFLOW 60i unit is effective to kill bacteria; however, modifications to this mode of operation would be required in order to increase the disinfection efficiency and to decrease the detention time. When the continuous flow system was run using a hydraulic detention time of 10 minutes and a single pass through the HydroFLOW unit, the E. coli removal efficiency was negligible. Further research is needed to determine the most economical and efficient reactor configuration in order to make the HydroFLOW unit competitive with conventional wastewater chlorination.

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12

Leung, Kai-shing Alex. "Control of disinfection by-products." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41549429.

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13

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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Paragliola, Raffaele. "Maximizing disinfection procedures in endodontics." Doctoral thesis, Università di Siena, 2021. http://hdl.handle.net/11365/1127093.

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The purpose of the present thesis was to evaluate/correlate different aspects of the endodontic treatment in order to shed some light on the influence of microorganisms disinfection during root canal treatment.

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15

Komvuschara, Kanyarat. "UV disinfection in comparison with other small scale disinfection technologies for the treatment of domestic greywater." Thesis, University of Hertfordshire, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247322.

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16

Sert, Caglayan. "Booster Disinfection In Water Distribution Networks." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610755/index.pdf.

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Disinfection of the municipal water systems is mostly achieved by means of chlorine addition at water treatment plants known as sources. Thus, there should be an adequate chlorine concentration at the source for an effective disinfection throughout the system by considering upper and lower limits of disinfectant. However, since the disinfectants are reactive and decays through the system, chlorine added at the source may not be enough to maintain desired disinfectant residuals which may lead to water quality problems in the water distribution system. Moreover, the disinfectants such as chlorine has also an effect to be carcinogen due to formation of disinfectant by-products. Thus, the system should balance the amount of disinfectant supplied while minimizing the health risk. In such a case, it is recommended that one or more booster disinfection stations can be located throughout the system. Such a method can provide more uniform distribution of the chlorine concentration while reducing the amount of the disinfectant used. In this thesis, optimum scheduling, and injection rates of the booster disinfection stations have been searched. The objective is to minimize the injected mass dosage rate subjected to the provision of adequate and more uniform residual concentration in the network. Determination of variable network hydraulics and chlorine concentrations is held out by EPANET network simulation sofware. A C++ code was developed to interface with EPANET by means of the EPANET Programmer'
s Toolkit for linear optimization of the disinfectant mass dosage rate applied to the network.

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17

Bond, Tom. "Treatment of disinfection by-product precursors." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/4005.

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Natural organic matter (NOM) in drinking water forms disinfection byproducts (DBPs) through reactions with disinfectants, typically chlorine. Many DBPs are harmful to human health. Potentially the most effective means of controlling DBPs is to remove NOM precursors before disinfection. However, both DBP formation and removal of precursors in natural waters are variable and unpredictable, reflecting the diverse and variable nature of NOM. To better understand the relationships between DBP formation, compound character and treatment, experiments were undertaken with a range of NOM surrogates, assessing both DBP formation and treatability. Activated aromatics, β-dicarbonyls, masked β-dicarbonyls and amino acids were indentified as reactive precursor categories. No correlations were found between compound physicochemical properties and DBP formation. This indicates reliable bulk predictors of DBP formation are unlikely to exist in natural waters. In contrast, treatability was explicable in terms of compound physicochemical properties. Levels of removal by coagulation and anion exchange were controlled by amount of anionic charge, while molecular weight and hydrophobicity also affect removal by activated carbon and nanofiltration. Advanced oxidation processes (AOPs) at high doses was able to completely mineralise all NOM surrogates, however at lower doses DBP formation can be increased, dramatically in the case of two amino acids. Biotreatment is effective in removing amino acids but can cause moderate increases in DBP levels. A DBP control strategy is outlined based on this information. Where a high proportion of DBP precursors are highly-anionic aromatic compounds, coagulation may be sufficient for DBP control. Where reactive precursors are moderately-anionic carboxylic acids, ion exchange should be considered. In waters where less-treatable NOM has a high DBPgenerating capacity, activated carbon should be investigated for removal of neutral or weakly-charged aromatic precursors and a (hydrophobic) nanofiltration membrane for neutral or weakly-charged amino acids or carbohydrates.

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18

Khaengraeng, Rungpetch. "Characterisation of solar photo-oxidative disinfection." Thesis, Northumbria University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402247.

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19

Dalrymple, Omatoyo Kofi. "Mechanistic Modeling of Photocatalytic Water Disinfection." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3057.

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The main goal of this research was to develop a mechanism-based model for photocatalytic disinfection of bacteria in water using suspended catalyst pthesiss in batch reactors. The photocatalytic disinfection process occurs as a semiconductor photocatalyst, most commonly titanium dioxide (TiO2), is irradiated with light of wavelength less than 380 nm to produce hydroxyl radicals and other highly reactive oxidants which can inactivate microorganisms. Photocatalytic disinfection involves a complex interaction of many fundamental mechanisms such as light absorption and scattering by semiconductor pthesiss, electrochemical surface reactions, and heterogeneous colloidal stability. Current models, based largely on chemical reacting systems, do not adequately account for these fundamental mechanisms. Even the Langmuir model developed for heterogeneous systems cannot describe the interactions of such large colloidal pthesiss. As a result, it is difficult to assess the combined effects of many important factors which go into the design of a photocatalytic disinfection system. A mechanistic modeling approach is desirable because it provides a framework to understand the influence of many important parameters on the disinfection process. It requires a description of the physical properties of the catalyst, the nature of the suspending electrolyte solution, the physical and chemical properties of the cell surface, and the energetic aspects that influence the interaction of the pthesiss. All these aspects are interrelated. While it is customary to envision the adsorption of reactants unto a catalyst surface, for photocatalytic disinfection involving suspended catalyst pthesiss, multiple catalyst pthesiss adhere to the bacterial surface. In this work a mechanistic model has been developed that simulates the effect of light intensity and catalyst concentration on the disinfection process. The simulations show good agreement with the experimental data for stable colloidal suspensions, that is, suspensions in which rapid aggregation of cells and TiO2 do not occur. Increased disinfection rates and high levels of inactivation can be achieved by maintaining a relatively low catalyst-to-microbe ratio while maximizing the light intensity. The influence of pH and ionic strength on the disinfection process have been included in the model, but these are only expected to be accurately predicted when the solution remains stable.

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20

Alotaibi, Modhawi. "Black Virus Disinfection in Chordal Rings." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31170.

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The topic of this thesis is black virus disinfection using mobile agents. The black virus is a faulty node that destroys any visiting agent without leaving a trace; moreover, once the black virus is triggered by an agent, it clones itself and spreads to neighbouring nodes. These viruses can only be destroyed if they move to nodes that have been occupied by agents. In this thesis, we consider the black virus disinfection problem in chordal rings. Initially, the system contains a single black virus that resides at an unknown location. We propose a solution that involves deploying a team of mobile agents to locate the original black virus and to prevent further damage once it has been triggered. Our protocol is divided into two phases: 1) searching the graph until the black virus is found and triggered and 2) sending agents to occupy the neighbouring nodes of the black virus in order to trigger and destroy all the black viruses at once. Our solutions are monotone, meaning that once a node has been explored it is protected from re-infection. In order to measure the efficiency of our protocol we consider the total number of agents required for disinfection, the overall number of black viruses and the number of moves required by the agents. We then analyze the cost of all our solutions, providing optimal bounds for some classes of chordal rings.

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21

Tree, Julia Anne. "The virucidal efficacy of wastewater disinfection." Thesis, University of Surrey, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387537.

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22

Gradel, Kim Oren. "Disinfection of Salmonella in poultry houses." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398775.

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23

Silvestry, Rodriguez Nadia. "Silver Disinfection in Water Distribution Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194756.

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Silver was evaluated as disinfectant to maintain water quality in water distribution system. It was used to inhibit growth of two opportunistic bacteria in planktonik form and in biofilm formation in Robbins devices with stainless steel and PVC surfaces. The results of this work show that silver is a potential secondary disinfectant to be used in water distribution systems

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24

Acosta, Vega Julio A. "Electro-Disinfection of Municipal Waste Water using Direct Current." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1899.

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Wastewater treatment has always been a problem to human settlers. Events such as the great stink of London during the summer of 1858 have pushed engineers into developing new technologies to deal with such wastes in effective and safe ways. Research projects like this aim to find ways of improving performance, economics, or environmental friendliness of treatment and disinfection methods. This thesis deals with the effectiveness, mechanisms of action, by-products and side effects of using DC current to disinfect secondary effluent. It is proposed as an alternative to conventional methods, such as chlorination, which are not always environmentally friendly or feasible. It was demonstrated that DC current efficiently kills pathogens. DC properly used achieves disinfection significantly higher than the minimum required by the EPA. Nevertheless disinfection by products such as residual chlorine should be taken into account when considering this technology as an alternative to conventional chlorination.

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25

Tamas, Andrea. "Successful promotion of solar water disinfection (SODIS) /." [S.l.] : [s.n.], 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000278508.

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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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Broers, Teresa. "Abruptio placentae and chlorination disinfection by-products." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63274.pdf.

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Kosa, Samia Abdulhamied. "Photoelectrocatalytic disinfection of E. coli by TiOâ‚‚." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407580.

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Wallis, C. "The ozone disinfection performance of rotary contactors." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315668.

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Wang, Tao. "Waterborne microorganism disinfection with pulsed UV light." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417348.

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Sicairos, Ruelas Enue Erdemely. "The Development of Alternative Methods of Disinfection." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194751.

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Chlorine is the primary method for disinfection of drinking water in the United States; however, growing concerns about the potential hazards associated with carcinogenic chlorine disinfection by-products have resulted in increased efforts to develop alternative methods of water disinfection. In addition, it is sometimes difficult to maintain an adequate concentration of free chlorine throughout a drinking water distribution system due to intrusion events and the presence of biofilms.Silver and copper are widely used as environmental biocides and as clinical antimicrobial agents. Copper has been extensively used as an algaecide for many years, and is reported to be one of the most toxic metals to heterotrophic bacteria in aquatic environments. In this study, silver and copper, both individually and in combination, were able to significantly reduce the numbers of the bacterial pathogens Salmonella typhimurium, Escherichia coli, Listeria monocytogenes, and Mycobacterium fortuitum in aqueous solutions. Silver and copper together could potentially be used as a secondary disinfectant in water treatment because their residual effect is long lasting and no harmful byproducts are generated.Besides water, produce can also be a source of microbial pathogens. Fruits and vegetables are the third leading source in microbial foodborne outbreaks, accounting for more than 10,000 cases of foodborne illness in the U.S. between 1990 and 2001. Alternative produce sanitizers in addition to chlorine were evaluated against foodborne pathogens inoculated onto lettuce. Overall, FitÂ® (citric acid, grapefruit oil extract) and chlorine yielded the greatest reductions of the study organisms.A large number of compounds are available for use as disinfectants; however, some are highly toxic, corrosive and produce harmful by-products. Natural antimicrobial products are another possible alternative. The efficacy of a natural peptide-based antimicrobial, Absolute Fx, was assessed against bacteria and viruses. Absolute Fx effectively inactivated the study organisms.

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Artiola, Janick F., Channah Rock, and Gary Fix. "Water Storage Tank Disinfection, Testing, and Maintenance." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2012. http://hdl.handle.net/10150/255333.

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Mangombo, Zelo. "The electrogeneration of hydroxyl radicals for water disinfection." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5745_1190373027.

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This study has shown that OHË radicals can be generated in an Fe/O2 cell from the electrode products via Fenton&rsquo
s reaction and used for water disinfection. The cell system in which the experiments were carried out was open and undivided and contained two electrodes with iron (Fe) as the anode and oxygen (O2) gas diffusion electrode. Typically, 100 ml of Na2SO4.10H2O (0.5M) solution was used as a background electrolyte. OHË radicals were produced in-situ in an acidic solution aqueous by oxidation of iron (II), formed by dissolving of the anode, with hydrogen peroxide (H2O2). The H2O2 was electrogenerated by reduction of oxygen using porous reticulated vitreous carbon (RVC) as a catalyst.

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Pole, Jason. "Quantifying misclassification in water disinfection by-product analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ53021.pdf.

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35

Szomolay, Barbara. "Analysis and control of a biofilm disinfection model." Diss., Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/szomolay/SzomolayB1206.pdf.

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36

Sanden, Gary Noble. "Disinfection of potable-quality water containing Legionella pneumophila." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/25377.

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37

Martin, G. C. "Development of an orally relevant biofilm disinfection model." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1346469/.

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This thesis describes the development and use of a novel microtitre plate biofilm system for testing the antimicrobial activity of test materials. The developed model is capable of high-throughput screening and furthermore the system has been shown to be stable and reproducible. The search for new antimicrobial agents for improved plaque control requires appropriate screening models. Key criteria for these models include; predictive of clinical data, orally relevant organisms (mixed species, bacteria present in biofilms), short contact time, rapid, reproducible and high throughput. The most widely used biofilm system for evaluating oral antimicrobials are the Constant Depth Film Fermentor (CDFF) and the Minimum Biofilm Eradication Concentration (MBEC) model systems. Each system has advantages for specific investingations; however neither and no other single system fulfils all of the criteria listed above. The CDFF is an orally relevant model that mimics biofilm development under constant salivary flow; typically the inoculum is derived from human dental plaque. Microbial analyses of in vitro growth show populations that are representative of in vivo plaque. However, the system is prone to contamination, is labour intensive and has limited capacity for testing multiple agents. The MBEC model investigates the antibacterial susceptibility of attached bacteria to the 96-pegs on the lid of a microtitre plate based system. Unfortunately, this model was not originally designed for use with oral bacteria; therefore, concerns exist for the use of the MBEC with oral bacteria including the development of oral biofilms on non-orally relevant surfaces such as polystyrene, as found in the MBEC pegs. The aim of this project was to develop a microtitre plate based biofilm assay that could assess the effects of antimicrobials against orally relevant biofilms grown on a relevant surface and compare it to recognised standard model systems. Biofilms derived from a defined inoculum were grown on hydroxyapatite-coated microtitre plate wells. Biofilm characteristics were assessed and were shown to be reproducible and allow for high-throughput screening. Antimicrobial testing showed a dose response and known actives were able to be 'ranked' in the same order as seen in clinical trials. This research has culminated in the development of a simple, high-throughput, reproducible 'off-the-shelf' method for the rapid screening of antimicrobial compounds against an orally relevant biofilm.

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38

Chavez, Reyes Xavier A. "Electrochemical Disinfection of Municipal Wastewater using Alternating Current." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1907.

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This research focused on chlorine-free disinfection of wastewater by complying with today's regulations. The equipment used was a continuous flow electrochemical reactor connected to an alternating current (AC) power supply. The electrodes used were made out of titanium coated with iridium oxide. To determine the inactivation of Escherichia Coli, a bacterial count method based on the USEPA method 1603 was used. After several experiments it was determined that electrochemical disinfection using AC was not efficient and economic enough to be classified as a viable alternative to chlorine disinfection. It was demonstrated that chlorine can be produced by electrolysis using AC and that no hydrogen could be noticed as a byproduct of the electrolysis of wastewater. When the results from this investigation were compared to the ones obtained using DC in Acosta (2014), it was determined that the belief that AC and DC are equally efficient at disinfecting wastewater is wrong.

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De, Grau Vidal Luis. "Field Study of Electrochemical Disinfection of Municipal Wastewater." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2064.

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Research on electrochemical disinfection of municipal wastewater has been conducted at the University of New Orleans using a continuous flow electrochemical reactor connected to a direct current (DC) power supply changing its polarity and varying the electrode distance. Bacterial inactivation and chlorine production were the main parameters that were recorded. After months of research, it was determined that the electrochemical disinfection reactor is efficient and has a great potential for the future. There is no need to use chlorine and it has low operation costs. The following design recommendations for an electrochemical disinfection unit were given: A detention time of 5 +- 0.3 minutes A minimum volumetric current density of 1000 amps/m3 A minimum detention current density of 80 amps.hr/m3 The combination of the three recommended design values yielded excellent disinfection efficiencies and low chlorine production.

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Martins, Celso Filipe Ferreira. "Functional polymers as antimicrobial agents for oral disinfection." Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/9539.

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Mestrado em Biologia Aplicada - Microbiologia Clínica e Ambiental
A flora microbiana da boca é uma das mais ricas e diversas do corpo humano. É no entanto, altamente variável de indivíduo para indivíduo, sendo por isso, impossível estabelecer com rigor o número e tipo de espécies que fazem parte desse bioma. Microrganismos patogénicos presentes na boca têm vindo a ser progressivamente associados a patologias de sistemas orgânicos que ultrapassam o âmbito estrito da cavidade oral. São diversos os casos descritos de endocardites, cancro, infeções respiratórias e até diabetes, provocados por microrganismos presentes na flora oral. Dada a relevância clínica que as infeções orais têm vindo a assumir nos últimos anos, o conhecimento detalhado sobre a composição da microflora oral e a sua suscetibilidade a compostos antimicrobianos passíveis de aplicação em desinfeção oral reveste-se de particular relevância. Foram efetuadas recolhas de amostras microbiológicas da boca de pacientes da clínica de medicina dentária universitária do Instituto Superior de Ciências da Saúde Egas Moniz, com o objetivo de isolar o maior número possível de estirpes encontradas para, posteriormente, se testar a eficácia antimicrobiana de dois oligómeros previamente sintetizados no decurso do projeto. Foram isoladas 103 estirpes, representando 37 espécies diferentes. Cada um dos 103 isolados obtidos foi caracterizado quanto à sua suscetibilidade aos compostos PMETOX-DDA e LPEI através da determinação da concentração mínima inibitória (MIC). Os valores médios de MIC obtidos foram de 0,530 mg.mL-1 para LPEI e 0,723 mg.mL-1 para PMETOX-DDA, sendo os valores de dispersão mais elevados para LPEI. Ambos os polímeros foram eficazes e, possivelmente, complementares enquanto agentes antimicrobianos. Os resultados deste estudo são consistentes com os previamente obtidos em ensaios microbiológicos preliminares, confirmando as poli-oxazolinas como uma promissora nova alternativa terapêutica em alternativa a agentes antimicrobianos convencionais. Paralelamente, informação sobre a composição da microflora dos diferentes compartimentos da boca foi analisada em conjunto com informação sobre a história clínica e hábitos de higiene oral de cada paciente, recolhidos por médicos dentistas através de observação e inquérito. Foram obtidos resultados significativos do teste não-paramétrico de Kruskal-Wallis (p <0,05) na análise a alguns hábitos de higiene e do historial clínico. Os valores da análise de similaridade e dissimilaridade entre grupos (SIMPER) foram estatisticamente relevantes, assim como a análise ANOSIM (global R = 0,765, com um nível de significância estatística de amostra de 0,1%) confirmando perfis de distribuição diferentes de acordo com as diferentes zonas da boca. A escovagem da língua e uso do fio dental são os hábitos de higiene oral mais relevantes na colonização oral por microrganismos.
The microbial flora of the mouth is one of the richest and most diverse in the human body. However, it is highly variable from individual to individual being, therefore, impossible to determine the exact number and kind of species that are part of this biome. Pathogens present in the mouth have been progressively associated with diseases of organic systems that go beyond the strict scope of the oral cavity. There are several reported cases of endocarditis, cancer, respiratory infections and even diabetes, caused by microorganisms in the oral flora. Given the clinical relevance that oral infections have been taking in recent years, a detailed knowledge about the composition of oral microflora and its susceptibility to antimicrobial compounds likely to be applied in oral disinfection, assumes particular relevance. Microbiological sampling of patients from the mouth of the university dental clinic of the Institute of Health Sciences Egas Moniz was conducted, in order to isolate the largest possible number of strains to subsequently test the efficacy of two antimicrobial oligomers, previously synthesized in the course of the project. A set of 103 strains, representing 37 different species, was obtained. Each of the 103 isolates was characterized for their susceptibility to compounds PMETOX-DDA and LPEI by determining the minimum inhibitory concentration (MIC). Mean obtained MIC values were 0.530 mg.mL-1 to LPEI and 0.723 mg.mL-1 to PMETOX-DDA, being dispersion values higher to LPEI. Both polymers were effective and possibly complementary as antimicrobial agents. The results of this study are consistent with results previously obtained in preliminary microbiological assays, confirming poly(oxazoline)s as a promising new therapeutic alternative to conventional antimicrobial agents. In addition, information on the composition of the microflora of the mouth of different compartments was analyzed along with information on the clinical history and oral hygiene habits of each patient, collected by dentists through observation and investigation. Statistically significant results of non-parametric Kruskal-Wallis test were obtained (p-value<0.05) for some hygiene habits and medical history events. SIMPER analysis values of dissimilarity between groups and similarity within groups were statistically relevant, as well as the ANOSIM analysis (global R=0.765, with a significance level of sample statistic of 0.1%), confirming the existence of different distribution profiles according to different areas of the mouth. Tongue brushing and flossing are the more relevant oral hygiene habits in oral colonization by microorganisms.

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Pole, Jason. "Quantifying misclassification in water disinfection by-product analysis." Ottawa : National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.nlc-bnc.ca/obj/s4/f2/dsk1/tape4/PQDD%5F0021/MQ53021.pdf.

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Patel, Nikita. "use of household bleach products for emergency disinfection." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/190716.

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Fitzpatrick, Heather L. "Covering chlorine contact basins at the Kanapaha Water Reclamation Facility effects on chlorine residual, disinfection effectiveness, and disinfection by-product formation /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010400.

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Moody, A. P. "A peroxide sensor for the food and beverages industry." Thesis, Cranfield University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269479.

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Cozzi, Pierluigi. "A study of the flow through ultraviolet disinfection systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ45452.pdf.

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Hardy, Scott Andrew. "Effectiveness of static mixers for disinfection of cryptosporidium oocysts." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20925.

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Kerwick, Mark Ian. "An evaluation of alternative technologies for drinking water disinfection." Thesis, University of Surrey, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594172.

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A methodology has been developed and used to evaluate the alternatives to chlorination for primary and residual drinking water disinfection. From the evaluation process it was concluded that at present none of the altemalives could viably replace chlorination for both primary and residual disinfection. The study did however highlight the potential of electrochemical disinfection technologies to provide primary and residual disinfection in the future by the generation of a range of oxidants including chlorine species. Hence, three electrochemical technologies (a mixed oxidant generator, a direct electrolyser with carbon aerogel electrodes, and a direct electrolyser called Zappi ™ )were chosen to assess their potential as an alternative to conventional chlorination for primary and residual disinfection. The disinfection efficiencies of the three devices were assessed. Anolyte produced from the mixed oxidant generator was compared directly with hypochlorite at equal doses. Anolyte was shown be more effective against E. coli, reducing the E. coli count by >6 logs and to have the same potential for trihalomethane formation in slow sand filtered water, generating 30).μg/L when dosed at lmg/L for 24 hours. The carbon aerogel and Zappi™ direct electrolysers were shown to disinfect E. coli in a range of electrolytes and water matrices. Total measurable E. coli log reductions were achieved in both devices using a chloride electrolyte. Significantly, both devices were effective against E. coli in sulphate electrolytes without the generation of chlorine, with 3 and 4 log reductions respectively. The carbon aerogel device was also shown to be effective in a good quality sewage effluent matrix and tap water reducing E. coli by >4 logs. Whilst, the Zappi was shown to reduce E. coli by >2 logs in slow sand filtered water. Phosphate was shown to significantly reduce disinfection in both direct devices. The effectiveness of the direct electrolysers was shown to be variable against other micro-organisms. The Zappi™ device was effective against the virus, bacteriophage MS2 in a sulphate electrolyte, with a >5 log inactivation after 30 minutes. Whilst, the carbon aerogel device achieved a > 1 Jog reduction of Enterovirus after 40 minutes in tap water and a 2 log reduction of Cryptosporidium oocysts in tap water. It should be noted that the reduction in Cryplosporidium could be attributable to removal via filtering rather than inactivation by oxidant attack. Possible mechanisms for electrochemical disinfection were investigated of these oxidant generation was shown t~ be responsible for disinfection_ Determination of the oxidant species generated proved to be problematic. The presence of chlorine and the high voltages used in all three devices made it difficult to isolate specific oxidants. The bactericidal properties of two poly-viologens were assessed 10 determine their potential for mediating oxidant generation for drinking water disinfection. The poly-viologens were shown to reduce the E. coli count by 6 logs. However, the results were inconclusive due to the variability between poly-viologen batches. These studies do however infer that poly-viologens may still have a future use as oxidant mediators in disinfection devices.

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Evaldsson, David, and Jakob Hahrs. "Prognostisering av efterfrågan : En fallstudie på Getinge Disinfection AB." Thesis, Linnéuniversitetet, Institutionen för ekonomistyrning och logistik (ELO), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-44582.

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Bakgrund: För företag är logistikverksamheten ett område som är av stor betydelse för lönsamheten. Lönsamheten förbättras genom att öka antingen vinstmarginalen eller kapitalomsättningshastigheten, där det senare kan erhållas genom att minska lager-nivåerna. Lager leder till ett antal kostnader, bland annat kapitalbindning. En viktig faktor inom lagerstyrningen är prognoser. Företag använder prognoser för att uppskatta produkternas framtida efterfråga i syfte att planera sin verksamhet. Då prognoser sällan stämmer mot verkligt utfall uppstår en osäkerhet. I lagerstyrningen täcks osäkerheten upp genom användning av säkerhetslager, som baseras på prognosmodellers avvikelser samt efterfrågevariationen. Därmed kan en förbättring av prognosarbetet minska kapitalbindningen, eftersom säkerhetslagernivån kan sänkas vid en reducering av osäkerheten. Syfte: Som ett led i fallföretagets eget arbete mot minskad kapitalbindning i säkerhets-lagret är syftet med studien att testa vilka prognosavvikelser olika prognosmodeller ger för Getinges komponenter i produktfamilj 46. Vidare är syftet att analysera vad som ligger till grund för prognosmodellernas utfall utifrån komponenternas olika efterfråge-strukturer. Slutsats: Studiens resultat visar vilka prognosavvikelser de utvalda prognosmodellerna genererar för komponenterna i Getinges produktfamilj 46. Författarna konstaterar att exponentiell utjämning är den prognosmodell som ger lägst prognosavvikelser gentemot verklig efterfråga. Anledningen beror på prognosmodellens utformning där närliggande och färskare information viktas högre än äldre data. Vidare visar studiens resultat att komponenternas efterfrågestruktur påverkar prognosmodellernas avvikelser. Komponenter med hög efterfrågad kvantitet, hög efterfrågefrekvens samt låg variation i efterfrågan bidrar till minskade prognosavvikelser. Detta gör att författarna kan bekräfta befintlig teori rörande hur produkters efterfrågestruktur påverkar prognosmodellers träffsäkerhet.

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Cheung, Chi-shing, and 張志成. "Economic valuation of UV disinfection in Hong Kong sewage." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31255802.

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Chia, Catherine Anne. "Effect of incident beam angulation on disinfection of dentinaltubules." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45165749.

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Dissertations / Theses on the topic 'Disinfection'

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