Providing pretreatment prior RO filtration is essential to avoid biofouling and subsequent loss of membrane performances. Chlorine is known to degrade polymeric membrane, improving or reducing membrane efficiency depending on oxidation conditions. This study aimed to assess the impact of alternative disinfectant, NH2Cl, as well as secondary oxidants formed during chloramination of seawater, e.g. HOBr, HOI, or used in water treatment e.g. ClO2, O3, on membrane structure and performances. Permeability, total and specific rejection (Cl-, SO4 2-, Br-, Boron), FTIR profile, elemental composition were analyzed. Results showed that each oxidant seems to react differently with the membrane. HOCl, HOBr, ClO2 and O3 improved membrane permeability but decreased rejection in different extent. In comparison, chloramines resulted in identical trends but oxidized membrane very slowly. On the contrary, iodine improved membrane rejection e.g. boron, but decreased permeability. Reaction conducted with chlorine, bromine, iodine and chloramines resulted in the incorporation of halogen in the membrane structure. All oxidant except iodine were able to break amide bonds of the membrane structure in our condition. In addition, chloramine seemed to react with membrane differently, involving a potential addition of nitrogen. Chloramination of seawater amplified membrane performances evolutions due to generation of bromochloramine. Moreover, chloramines reacted both with NOM and membrane during oxidation in natural seawater, leading to additional rejection drop.

Ozone is a powerful oxidant and disinfectant used in potable wastewater reuse to destroy specific harmful compounds, including pharmaceuticals, personal care products and endocrine disrupting compounds. Ozonation also increases the biodegradability of recalcitrant organic compounds and inactivates disease-causing microbes. However, bromate, a regulated possible human carcinogen can form when bromide is present due to natural or industrial sources. Pilot-scale testing on wastewater treatment plant effluent with high bromide concentrations showed that the addition of preformed monochloramine could reduce bromate formation by as much as 97%. Monochloramine addition was able to keep concentrations below the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 µg/L while exceeding 3-log or 99.9% virus removal credit. Preforming monochloramine in separate carrier water prior to addition upstream of ozonation eliminated the potential for disinfection byproduct formation when monochloramine is formed in the main water flow. This also allowed for the mechanisms of bromate suppression by monochloramine to be examined without the influence of reactions between chlorine and dissolved organic matter present. This research can help increase the application of ozonation in water reuse. / MS / Ozone is a powerful oxidant and disinfectant used in potable wastewater reuse to destroy specific harmful compounds, including pharmaceuticals, personal care products and endocrine disrupting compounds. Ozonation also increases the biodegradability of recalcitrant organic compounds and inactivates disease-causing microbes. However, bromate, a regulated possible human carcinogen can form when bromide is present due to natural or industrial sources. Pilot-scale testing on wastewater treatment plant effluent with high bromide concentrations showed that the addition of preformed monochloramine could reduce bromate formation by as much as 97%. Monochloramine addition was able to keep concentrations below the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 µg/L while exceeding 3-log or 99.9% virus removal credit. Preforming monochloramine in separate carrier water prior to addition upstream of ozonation eliminated the potential for disinfection byproduct formation when monochloramine is formed in the main water flow. This also allowed for the mechanisms of bromate suppression by monochloramine to be examined without the influence of reactions between chlorine and dissolved organic matter present. This research can help increase the application of ozonation in water reuse.

Chloramines are used for disinfection in many water treatment facilities because of their ability to provide residual protection of water supplies while minimizing the formation of disinfection-by-products. However, chloramines can impart taste and odor to the water, which can lead to customer complaints. Furthermore, the removal of monochloramine from water is essential for certain industries. Previous research at the University of Texas at Austin has demonstrated the potential of several granular activated carbons (GAC) for removal of monochloramine under conditions typical of water treatment plants. The goal of this research project is to further quantify steady-state monochloramine reduction in fixed bed reactors (FBR) with three commercially available GACs, and improve the understanding of the physical and chemical properties that influence removal. The research was divided into 3 phases: 1. A laboratory scale fixed bed reactor experiment was used to quantify steady state monochloramine removal over time. City of Austin tap water viii was used for three GAC types (Jacobi CAT, Norit CAT, Nority CNS) at pH 8 and 9. 2. Physical characterization of each GAC was performed using analysis of nitrogen adsorption isotherms. Specific surface area, pore volume, and pore distribution were determined. Chemical characterization was performed quantitatively using Boehm titrations. Qualitative analysis was performed by analyzing FTIR spectra of untreated activated carbon samples. 3. The Monochloramine Catalysis (MCAT) model was calibrated using results from the Phase 1 and 2 experiments. Simulations of full scale point of use drinking water filters were run for various empty bed contact times and influent monochloramine concentrations. These results were compared against National Sanitation Foundation monochloramine reduction certification criteria. Results show that steady state removal was achieved for all of the activated carbons tested and this removal efficiency can reach nearly 90% using a 0.75-minute empty bed contact time. This steady state performance indicated that catalysis of the monochloramine was occurring, and removal could theoretically occur for very long periods of time. The second stage of the research shows correlation between chemical characteristics (acidity and basicity) and removal efficiency. Furthermore, physical characteristics, mainly micro-porosity, were shown to largely impact performance. Finally, the MCAT model provides a reasonable estimate of steady state removal, and is used to predict full scale point of use performance. / text

Maintaining water quality in distribution systems has become a prominent issue in the study of water networks. This thesis concentrates on disinfectant and particle counts as two important indicators of water quality. The models discussed in this work are based on data collected by the author. The experimental set-up and procedure are described and observations of particle counts, particle counter size distributions, monochloramine as disinfectant, temperature, heterotrophic plate counts and epifluorescence microscopy counts are reported. A model of the response of particle counts to an increase in flow is developed. This model is obtained from specification derived from the data and assumptions, and is validated by its interpretability and its fit to data. A local shear-off density and an initial biofilm shedding profile were introduced and thus a linear model for this part of the water quality dynamics could be obtained. A procedure for the identification of the parameters of the local shear-off function and for the determination of the biofilm shedding profile is presented. This profile can be used to provide information about the status of the distribution system in terms of shear-off from the biofilm on the pipe walls. Monochloramine decay dynamics are investigated. The chlorine meter data is preprocessed with the help of titration data to correct meter drift. The data is then used in calibrating two different possible chlorine models: a model with a single decay coefficient and a model with bulk decay coefficient and wall demand (as used in Epanet). Important difficulties in identifying these parameters that come about because of the structure of the models are highlighted. Identified decay coefficients are compared and tested for flow, inlet chlorine and temperature dependence. The merits and limits of the approach to modelling taken in this work and a possible generalisation are discussed. The water industry perspective and an outlook are provided.

The antibacterial agent, triclosan, is widely used in many household personal care products, and it has recently been detected in wastewater treatment plant effluents and in source waters used for drinking water supply. Accordingly, the reactivity of triclosan with the disinfectants used in wastewater treatment and in the production of potable water is of interest. Monochloramine is used as an alternative disinfectant in drinking water treatment to minimize production of regulated disinfection by-products. This study examined the reactions between triclosan and monochloramine and involved analysis of monochloramine and triclosan decay and product formation under drinking water treatment conditions over a pH range of 6.5 to 10.5. Monochloramine decay in the presence of triclosan was measured relative to monochloramine auto-decomposition in the absence of triclosan using UV-VIS spectrophotometry. Experimental results showed that the monochloramine auto-decomposition intermediates, free chlorine and dichloramine, are responsible for a majority of the observed triclosan decay and product formation. A kinetic model for monochloramine auto-decomposition was modified to include terms and rate coefficients for the reactions of triclosan with monochloramine (<i>k</i> = 90.4 M^-1h^-1), free chlorine (<i>k</i> = 1.94&#215;10⁷ M^-1h^-1), and dichloramine (<i>k</i> = 2&#215;10⁵ M^-1h^-1), and was able to predict triclosan and monochloramine decay. It was determined that the reactions of dichloramine and free chlorine with triclosan were 10³ and 10⁵ times faster, respectively, than the reaction of monochloramine with triclosan. The products of these reactions, detected using GC-MS, included three chlorinated triclosan intermediates, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. Low levels of chloroform were detected at pH values of 6.5 and 7.5. / Master of Science

Les circuits de refroidissement des centrales nucléaires en bord de rivière sélectionnent par leur mode de fonctionnement des micro-organismes à caractère thermophile, parmi lesquels le micro-organisme pathogène, Legionella pneumophila. Pour lutter contre le développement de ce genre bactérien, un traitement de désinfection de l’eau des circuits de refroidissement à la monochloramine peut être employé. Pour participer à la maitrise des risques sanitaires et environnementaux liés à la modification physico-chimique et microbiologique de l’eau naturelle prélevée, EDF s’est engagé dans une démarche d’amélioration des connaissances sur l’écologie de Legionella pneumophila dans les circuits de refroidissement et des liens que cette espèce bactérienne entretient avec son environnement (physico-chimique et microbiologique) favorisant ou non sa prolifération. Ainsi, la diversité et la dynamique des Legionella pneumophila cultivables ont été déterminées dans les quatre centrales nucléaires en bord de Loire pendant un an et leurs liens avec leur environnement physico-chimique et microbiologique ont été étudiés. Cette étude a mis en évidence une forte diversité des sous-populations de Legionella pneumophila et une apparente dynamique qui semble être liée à l’évolution d’un nombre restreint de sous-populations. Les sous-populations de Legionella pneumophila semblent entretenir des relations souche-spécifiques avec les paramètres biotiques et présenter des sensibilités différentes aux variations physico-chimiques du milieu. La conception des circuits de refroidissement pourrait impacter la communauté de légionelles. L’utilisation de la monochloramine perturbe fortement l’écosystème mais ne sélectionne pas de populations tolérantes au biocide. / The cooling circuits of nuclear power plants, by their mode of operating, can select thermophilic microorganisms including the pathogenic organism Legionella pneumophila. To control the development of this species, a disinfection treatment of water cooling systems with monochloramine can be used. To participate in the management of health and environmental risks associated with the physico-chemical and microbiological modification of water collected from the river, EDF is committed to a process of increasing knowledge about the ecology of Legionella pneumophila in cooling circuits and its links with its environment (physical, chemical and microbiological) supporting or not their proliferation. Thus, diversity and dynamics of culturable Legionella pneumophila were determined in the four nuclear power plants along the Loire for a year and their links with physico-chemical and microbiological parameters were studied. This study revealed a high diversity of Legionella pneumophila subpopulations and their dynamic seems to be related to the evolution of a small number of subpopulations. Legionella subpopulations seem to maintain strain-specific relationships with biotic parameters and present different sensitivities to physico-chemical variations. The design of cooling circuits could impact the Legionella pneumophila community. The use of monochloramine severely disrupts the ecosystem but does not select biocide tolerant subpopulations.

Although the kinetics and mechanism of monochloramine decay in organic-free waters are relatively well understood, those in natural waters are not, due to exceedingly complex and poorly defined interactions of monochloramine with natural organic matter (NOM) and particles. Ozonation followed by a biologically activated carbon (BAC) filtration is a commonly practiced process option that affects the characteristics of both dissolved and particulate constituents in the water. However, how these changes in water constituents affect stability of the residual disinfectant, or monochloramine in particular, are currently unknown. Kinetics of monochloramine decay in water samples obtained before and after ozonation and BAC treatments were performed under varying operating conditions were determined by bench-scale batch experiments. Stability of monochloramine in the BAC filter effluent samples obtained at different times after backwashing was determined. It was found that in most cases monochloramine stability was greatly decreased after BAC filtration. Further filtering the BAC effluents with 1.2 and #61549;m polycarbonate membrane resulted in a substantial increase in monochloramine stability. A further increase was observed after filtering the samples using a 0.4 m membrane. This finding suggested that particulate matter generated from the filters could be the major cause of monochloramine instability. The fines from the activated carbon, possible components of the particulate matter eluting from the BAC filters, were found to exert an insignificant monochloramine demand both in the presence and absence of NOM, which is contrary to previous speculation in the literature about their demand for monochloramine. While there appears to exist a relationship between chloramine demand and HPC count of the filter effluent, more research will be needed to determine the effect of nature and type of microorganisms and their byproducts have on chloramine demand. Effect of ozonation on monochloramine stability is also under investigation using both the water sampled from full-scale plant and the synthetic water prepared with Suwannee River NOM.

Mycobacterium avium, an opportunistic human pathogen, infects between 25 and 50% of advanced-stage acquired immuno-deficiency syndrome (AIDS) patients in the United States. M. avium has been isolated from many environmental sources including: natural waters, soils, and aerosols. M. avium has also been recovered from within municipal and hospital drinking water systems. Rhesus macaques (Macaca mulatta) infected with the simian HIV analog, SIV, have been shown to acquire M. avium infections from potable water. Reduced-aggregate fractions (cell suspensions free of large aggregates) of Mycobacterium avium were exposed to chlorine, monochloramine, chlorine dioxide, and ozone and kinetics of disinfection measured. Chlorine disinfection kinetics was also measured in M. avium cultures grown in biofilms. M. avium exhibited a high resistance to chlorine compared to E. coli. M. avium CT99.9% (disinfectant concentration x time to 3 logs cell inactivation) values were between 571- and 2318 -times those of E. coli. Clinical isolates of M. avium showed 0.24 and 2.5-fold increase in resistance to chlorine compared to their pulsed-field-gel-electrophoresis- (PFGE) matched environmental isolates. M. avium strains exhibited a mixed response to exposure to monochloramine. The CT99.9% values of three strains (2 clinical, 1 environmental) were between 6.3- and 23.5- times that of E. coli. Two strains (1 clinical, 1 environmental) exhibited CT99.9% values approximately the same as E. coli, a difference from all the other disinfectants which were much less effective on M. avium than on E. coli. M. avium strains exhibited a high resistance to chlorine dioxide when compared to E.coli. M. avium CT99.9% values of between 133- and 706- times higher that that of E. coli. In the paired isolates tested, the clinical isolate was 5.3 times more resistant than the matched environmental isolate. M. avium exhibited a high resistance to ozone when compared to E. coli. M. avium strains exhibited a CT99.9% value of between 52 and 90 times higher that that of E. coli. In the paired isolates tested, the clinical isolate was nearly identical as judged by CT99.9% values. M. avium strain 5002 exhibited an unusual disinfection kinetics curve. Disinfection rate increased by a non-logarithmic factor, indicating that inactivation efficiency was increasing over time. M. avium strain 1060 showed between a 17% decrease to a 265% increase in CT99.9% value when grown as biofilms as opposed to suspension. Due to the large variance in biofilm density and and CT99.9% values, any conclusions based on these experiments should be considered tentative at best. M. avium's resistance to chlorine and chlorine dioxide approaches that of the protozoan cysts of Giardia muris and Entamoeba hystolytica. M. avium is much less resistant, relatively, to monochloramine possessing values similar to E. coli. Ozone resistance of M. avium is two orders of magnitude greater than E. coli and one order of magnitude of less than G. muris cysts. A critical concentration threshold level for chlorine dioxide was found. That is, there was no linear relationship between concentration of chlorine dioxide and cell inactivation. Initial experiments using a range of concentrations from 0.1 ppm to 0.5 ppm chlorine dioxide showed a biphasic curve with the inflection point (indicating the critical concentration) between 0.3 and 0.4 ppm chlorine dioxide. / Master of Science

Ozonation is an integral process in ozone-biofiltration treatment systems and is beginning to be widely adopted worldwide for water reuse applications. Ozone is effective for pathogenic inactivation and organics oxidation: both increasing assimilable organic carbon for biofiltration and eliminating trace organic contaminants which may pose a threat to human health. However, ozone can also form disinfection byproducts such as bromate from the oxidation of naturally occurring anion bromide. Bromate is a known human carcinogen and is regulated by the EU, WHO, and USEPA to a maximum limit of 10µg/L. In waters high in bromide, especially above 100µg/L, bromate formation becomes a major concern. In the secondary wastewater effluent studied, bromide concentration may exceed 500µg/L. Several bromate suppression techniques have been devised in previous work, including free ammonia addition, monochloramination, and the chlorine-ammonia process. While free ammonia addition was not found to adequately reduce bromate formation below the required MCL, monochloramine addition and the chlorine-ammonia process were found to be effective. However, the impact of these chemical suppression techniques on organics oxidation and disinfection has not been fully studied. This study explored the impact of these bromate suppression techniques at a wide range of ozone doses on bromate formation, pathogenic inactivation, ozone-refractory organics oxidation through the surrogate 1,4-dioxane, and N-nitrosodimethylamine (NDMA) formation. Additionally, bromate suppression mechanisms of monochloramine were explored further through a variety of different water quality parameters, such as through hydroxyl radical exposure and ultraviolet absorption spectrum measurements, which were correlated and utilized to develop a hydroxyl radical exposure predictive model. / Master of Science / Ozone is a powerful oxidant used in water treatment in order to degrade contaminants of emerging concern into less harmful moieties and to inactivate pathogens. Upon application to process water, ozone quickly reacts with constituents in the water to form hydroxyl radicals: the most powerful oxidant in water treatment. These hydroxyl radicals, though with extremely short half-lives, are able to degrade ozone-recalcitrant organics, such as 1,4-dioxane through a process called advanced oxidation. Ozone itself also has the capability of inactivating a multitude of pathogenic organisms, including viruses Giardia and Cryptosporidium parvum when specific contacts times are met. However, ozone does have the potential to form disinfection byproducts such as Nnitrosodimethylamine (NDMA) and bromate. NDMA, though not currently regulated by the United States’ Environmental Protection Agency (USEPA), has a drinking water health advisory limit of 10ng/L in the State of California. Bromate, on the other hand, is a known human carcinogen regulated to 10µg/L by the USEPA. Formed within the ozone system from the naturally occurring ion bromide, bromate can be limited through various chemical treatments such as ammonia addition, pH adjustment, monochloramination, and the chlorine-ammonia process. To date, these methods of bromate suppression have not been comprehensively studied in terms of bromate suppression as well as disinfection and organics oxidation in water reuse systems. The purpose of this research was to minimize bromate formation while ensuring NDMA formation was minimized, and disinfection and organics oxidation were maximized. Through this study, system efficiencies were improved and water quality for future generations will be improved.

Ce travail décrit la réactivité du chlore et de la monochloramine sur les aminophénols en solution aqueuse.Cette étude a ciblé, d'une part la détermination des vitesses réactionnelles de chloration et de monochloramination des aminophénols et d'autre part, l'identification des sous-produits d'oxydation formés.Les demandes en oxydant et le potentiel de formation en composés organohalogénés adsorbables (AOX), chloroforme, acides haloacétiques (HAA) and haloacétonitriles (HAN) ont été déterminés lors de la chloration et la monochloramination des aminophénols. Les 3-aminochlorophénols et le 2-amino-3H-phénoxazin-3-one (APX) ont été respectivement identifiés lors de la monochloramination de 3AP et 2AP.L'étude cinétique de la chloration des aminophénols en réacteur continu a montré que les vitesses sont du même ordre de grandeur pour le 2-aminophénol (2AP) et le 3-aminophénol (3AP) à pH neutre. La modélisation cinétique de la chloration du 3AP a indiqué que la forme aminophénolate est la plus réactive vis-à-vis du chlore.Quant à l'étude cinétique de monochloramination du 3AP en réacteur fermé, elle a permis de conclure que la vitesse de monochloramination diminue en passant du pH 7 à 9 et la forme neutre de 3AP est la plus réactive vis-à-vis de la monochloramine. Par comparaison, la vitesse de chloration du 3AP a été plus importante d'un facteur 105 à celle de la monochloramination. / This work describes the reactivity of chlorine and monochloramine with aminophenols in aqueous solution. Chlorination and monochloramination kinetic rates of aminophenols were investigated, first and final oxidation by-products were identified.Oxidant demands and formation potential of adsorbable organic halides (AOX), chloroform, haloacetic acids (HAA) and halonitriles (HAN) were determined during the chlorination and the monochloramination of aminophenols. The 3-aminochlorophenols and the 2-amino-3H-phenoxazin-3-one (APX) were respectively identified during the monochloramination of 3AP and 2AP.Chlorination of aminophenols in a continuous flow reactor showed that the kinetic rates of 2-aminophenol (2AP) and 3-aminophenol (3AP) have the same order of magnitude at neutral pH. Kinetic modelling of 3AP chlorination indicated that aminophenolate is the most reactive species with chlorine.Monochloramination kinetics of 3AP in a batch reactor showed that the rate of monochloramination decreases when pH increases from 7 to 9 and the neutral form of 3AP is the most reactive with monochloramine. In comparison, chlorination rate of 3AP was estimated to be 105-fold higher than monochloramination rate.