nÃo hà / O presente trabalho tem por objetivo avaliar a formaÃÃo de compostos orgÃnicos halogenados, especificamente trihalometanos (THM), em um Sistema de Abastecimento de Ãgua que utiliza tecnologia de filtraÃÃo direta descendente, prÃ-oxidaÃÃo com diÃxido de cloro, coagulaÃÃo com cloreto de polialumÃnio, auxiliado por um polÃmero catiÃnico e desinfecÃÃo com cloro liquefeito. Priorizou-se na avaliaÃÃo o estudo dos principais parÃmetros que influenciam a formaÃÃo de trihalometanos em meio aquoso: pH do meio, tempo de contato, temperatura, concentraÃÃo de brometos e residual de cloro livre. Adicionados a estes, foram avaliados parÃmetros operacionais, como a eficiÃncia reacional do processo de produÃÃo de diÃxido por geradores instalados na EstaÃÃo, planos de controle da difusÃo dos THM por toda extensÃo da rede de abastecimento, interferÃncia das estaÃÃes climÃticas da regiÃo (quadra chuvosa e seca), a influÃncia do agente limitante no processo reacional para a produÃÃo de diÃxido de cloro, os pontos de dosagem dos oxidantes utilizados e a distribuiÃÃo dos pontos de amostragem na rede de distribuiÃÃo de Ãgua. Destes parÃmetros, destacam-se, prioritariamente, as elevadas concentraÃÃes de THM observadas na Ãgua distribuÃda, onde somente 36% das amostras coletadas apresentaram valores inferiores ao limite determinado pela Portaria 518/2004 do MinistÃrio da SaÃde. Dentre os trihalometanos identificados, verificou-se formaÃÃo mais acentuada do clorofÃrmio, seguido do bromodiclorometano, dibromoclorometano e bromofÃrmio, tendo sido o cloro o agente que mais viabilizou a formaÃÃo de subprodutos no sistema. Destes, o clorofÃrmio e o bromodiclorometano foram as espÃcies formadas em maior quantidade no perÃodo seco e, no perÃodo chuvoso, os compostos dibromoclorometano e bromofÃmio. Observou-se que o diÃxido de cloro, produzido a partir de Ãcido clorÃdico e clorato de sÃdio, conferiu residual de cloro livre ao meio, potencializando a formaÃÃo de organoclorados. Constatou-se que o tempo de detenÃÃo da Ãgua nas redes de distribuiÃÃo à um fator que contribui para a elevaÃÃo da taxa de formaÃÃo dos THM, e que os planos de amostragem nestas redes necessitam de critÃrios especÃficos de coleta. O atual cenÃrio qualitativo da Ãgua tratada em toda extensÃo do sistema de abastecimento investigado, requer brevidade em aÃÃes estratÃgicas para a mitigaÃÃo dos fatores que potencializam a formaÃÃo dos THM, evitando comprometer a saÃde pÃblica da regiÃo estudada. / This study aims to evaluate the formation of halogenated organic compounds, specifically trihalomethanes in a Water Supply System that uses direct descendant filtration technology, pre-oxidation with chlorine dioxide, coagulation with polyaluminium chloride aided by a cationic polymer. This paper considered the main parameters that influence the formation of trihalomethanes in aqueous medium, according to results of research in the specialized technical literature, namely: pH, contact time, temperature, concentration of bromide and residual chlorine. Additionally, it was evaluated a few items of operational processes that exert an influence on the potential for formation of by-products, such as reaction efficiency of the production process of dioxide by generators installed at the treatment station, plans to control the spread of the THM throughout the water supply network, the interference of the weather (rainy season and dry season), influence of the limiting agent in the reaction process to produce chlorine dioxide, the dosing points of the oxidants used and the definition of control points in the water supply network. These parameters are highlighted as a priority: the high THM concentrations observed in the water distributed, where only 36% of the samples had values below the limit determined by the existing laws of Ministry of Health. Among the trihalomethanes identified, Chloroform was most frequently detected, followed by bromodichloromethane, dibromochloromethane and bromoform, that indicates chlorine as the agent that more enables the formation of by-products in the system. The current scenario of the treated water quality all along the supply system investigated, requires strategic actions to mitigate the factors that increase the formation of THM avoiding to compromise public health in the region studied.

Este projeto de pesquisa foi desenvolvido visando quantificar possíveis distúrbios de vazão em emissores do tipo gotejador (irrigação localizada) submetidos à aplicação de cloro livre e acidificação em condições estática e dinâmica de fluxo de água no sistema. O experimento foi realizado no período de setembro de 2005 a junho de 2006, utilizando-se 14 modelos de gotejadores autocompensantes com suas respectivas linhas gotejadoras montadas em uma bancada de ensaios em estrutura metálica. Os tratamentos utilizados no experimento foram: a) aplicação dinâmica de 100 mg L-1 de cloro livre com pH na faixa de 5,5 a 6,0; b) aplicação estática de 100 mg L-1 de cloro livre com pH na faixa de 5,5 a 6,0; c) aplicação de ácido nítrico com pH na faixa de 2,0 a 3,0 durante ½ h (sistema pressurizado); d) aplicação de ácido nítrico com pH na faixa de 2,0 a 3,0 durante 12 h (sistema pressurizado). Foram realizadas curvas vazão versus pressão para cada tratamento em três diferentes temperaturas da água (15, 25 e 40° C). O delineamento experimental utilizado foi o inteiramente aleatorizado em esquema fatorial, com utilização dos testes ?F? para análise de variância e Tuckey, a 5% de significância, para comparação de médias e análise de regressão. Os resultados obtidos mostram que para o tratamento da água com 100 mg L-1 de cloro livre em condição dinâmica, ocorreu um decréscimo de 10 a 20% em média da vazão (L h-1) para alguns modelos de gotejadores mais sensíveis aos produtos químicos, sendo que o modelo I apresentou redução drástica de vazão na ordem de 100% em virtude do bloqueio total do labirinto do emissor, em decorrência do aumento de 112% do volume da membrana após 2688 h de aplicação contínua de cloro. Os tratamentos estáticos não apresentaram variações acentuadas de vazão média (L h-1), coeficiente de variação (%), uniformidade de distribuição (%), Vazão Relativa (%) e Grau de Entupimento (%). Verificou-se relação linear entre a vazão e a temperatura da água para os gotejadores novos, sendo que após a aplicação dos diferentes tratamentos, as curvas vazão versus pressão para cada modelo de gotejador sofreram influência tanto da pressão quanto da temperatura de maneira distinta. / This research project was developed to quantify possible flow rate variation in emitters (drip irrigation) submitted to the application of free chlorine and acidification under static and dynamics conditions of water flow. The experiment was accomplished in the period of September, 2005 to June, 2006, being analyzed 14 models of pressure compensating emitters set up in a metallic bench. The treatments used in the experiment were the following ones: a) dynamic application of 100 mg L-1 of free chlorine with pH 5,5 to 6,0; b) static application of 100 mg L-1 of free chlorine with pH 5,5 to 6,0; c) application of acid nitric with pH 2,0 to 3,0 during ½ h (pressurized system); d) application of acid nitric with pH 2,0 to 3,0 during 12 h (pressurized system). The operating pressures and emitter model combination were: 50, 100, 200, 300, 400 kPa for emitters A to N, in three different water temperatures (15, 25 and 40° C). The obtained values of flow rate were used to calculate the CUD, CV, relative flow rate, the percentage of drippers in each flow rate range, and the number of the drippers completely clogged. The statistical analysis of the treatments were accomplished by Tukey test at 5% probability. The obtained results show that for the treatment of the water with 100 mg L-1 of free chlorine in dynamic condition, a reduction from 10 to 20% of the flow rate (L h-1) occurred for some models more sensitive to chemical products. Model I presented drastic reduction of flow rate in the order of 100% by total blockade of the labyrinth of the emitter, due to the increase of 112% of the volume of the membrane after 2688 h of continuous application of 100 mg L-1 of chlorine free with pH 5,5 to 6,0. The static treatments didn\'t present accentuated variations of medium flow rate (L h-1), variation coefficient (%), distribution uniformity (%), relative flow rate (%) and degree of blockage (%). For pressure compensating emitters, where the discharge sensitivity to temperature is insignificant, after the application of the different treatments, the measured discharge/pressure relationship for each emitter model was sensitive to pressure as well to temperature.

A escassez de água e a grande geração de esgoto doméstico com necessidade de tratamento estimulam o uso de águas residuárias na agricultura. A irrigação por gotejamento caracteriza-se como um sistema seguro para esta finalidade, mas possui como barreira tecnológica o entupimento dos gotejadores. Neste trabalho, objetivou-se selecionar modelos de gotejadores e manejos mitigadores do entupimento por uso de água residuária oriunda de tratamento secundário de esgoto doméstico. Desenvolveu-se o estudo em três etapas: (I) a caracterização de 15 modelos de gotejador novos, (II) a préseleção dos emissores e (III) a seleção da combinação manejo e modelo. Os manejos foram controle, cloração a 0,5 mg L-1 de cloro residual livre ao final da irrigação medido ao final do sistema, ar comprimido a 1,96 kPa na entrada dos emissores e a combinação de cloração e ar comprimido, utilizando-se filtragem de areia (De = 0,59 mm), disco (120 mesh) e tela (200 mesh) em todos os tratamentos. Procederam-se avaliações de vazão e cálculos de coeficiente de variação de vazão (CVq) e de grau de entupimento (GE). Os modelos apresentaram coeficiente de variação de fabricação aceitável e diferentes sensibilidades ao entupimento. O entupimento foi parcial, ocorreu de maneira desuniforme, independente da uniformidade de distribuição de água (UD) do emissor novo, e surgiu pela formação de biofilme bacteriano associado a sólidos dissolvidos. Houve aumentos de vazão em alguns modelos. A cloração reduziu o grau de entupimento ao longo do tempo e evitou o entupimento total em emissores. O modelo B associado à cloração apresentou a maior probabilidade de encontrar emissores na faixa de 5 % de variação de vazão em relação aos novos e o modelo M associado à filtragem ou a tratamentos com ar comprimido, as menores probabilidades. Os manejos mostraram-se semelhantes quanto ao GE e ao CVq e obtiveram-se valores de UD inferiores a 60 %, CVq superiores a 20 % e GE superiores a 5 %. Finalmente, de acordo com o objetivo, selecionou-se o modelo B associado à cloração como a combinação que melhor atenuou o entupimento dos emissores. / The sustainable management of water resources, given the current and projected severe water shortages, requires that appropriate methods of water usage be implemented. One of these is the application of treated wastewater to agricultural land using drip irrigation systems, which is safe and among the most resource efficient methods of irrigation. However, the use of drip irrigation with wastewater is constrained by the potential for clogging in the emitters. To elucidate the mechanism of clogging, fifteen drip emitters models from different manufacturers were tested with secondary treated wastewater in the laboratory and two field experiments were conducted to evaluate emitters and treatments according to the degree of clogging (DC) and flow rate coefficient of variation (CVq). The treatments were control (filtrage only), chlorination (0.5 mg L-1 free residual chlorine injected at the end of each irrigation cycle), compressed air (1.96 kPa in the inlet drippers) and the chlorine and compressed air combination. The manufacture coefficient of variation was acceptable and different clogging susceptibility. The clogging was partial, non-uniform and was caused by biofilm with dissolved solids. Some drippers with overflow rates were noted. The chlorination decreased clogging overtime and reduced the complete clogging. The dripper model B (pressure compensated, flat and inserted in the line, with rectangular elastic membrane over a 30 mm passageway, 0.8 mm narrowest aperture, 1.61 L h-1 under 98 kPa) with chlorination was identified as having the best performance, with the highest number of emitters with a flow rate within five percent of the flow rate when new, and the dripper model M with chlorination was the worst performance with the lowest percent. The filtrage, chlorine and air treatments did not have a statistically significant affect in the DC or CVq. Distribution uniformities higher than 60 %, CVq higher than 20 % and DC higher then 5 % were found. Finally, according to the purposed, It was selected the dripper model B with chlorination as the best combination to mitigate the clogging

[pt] A cinética da carbocloração do pentóxido de vanádio (V2O5) puro, pelo tratamento com gás cloro, de misturas sob a forma de pó, não-compactadas, de V2O5 e grafite (agente redutor), foi investigada, com o emprego do método termogravimétrico, no intervalo de 350 a 550°C, sendo estudada a influência, sobre a velocidade de reação, das seguintes variáveis: temperatura de cloração, percentagem de agente redutor na amostra inicial e pressão parcial do cloro. Na avaliação do efeito da temperatura de cloração sobre a cinética da reação, o Modelo do Núcleo Não Reagido foi utilizado para interpretar os resultados experimentais obtidos. O valor calculado para a energia de ativação da reação foi de 52 kJ, na faixa de 350 a 400°C, sugerindo a reação química como a etapa controladora do processo, e de 12 kJ, na faixa de 400 a 550°C, caso em que a difusão do gás reagente (condições fluidodinâmicas) poderia ser o mecanismo controlador. O efeito da percentagem de carbono, no intervalo de 17 a 30%, nas temperaturas de 350 e 500°C, revelou comportamentos distintos da reação, sugerindo a predominância, conforme o caso estudado, de fatores diferentes, tais como o contato sólido-sólido, atuando para aumentar a taxa de reação, e o excesso estequiométrico de carbono ou a dificuldade de penetração do gás reagente, concorrendo para diminuir a taxa de reação. A reação investigada caracterizou-se por ser aproximadamente de segunda ordem em relação ao cloro, à temperatura de 350°C, e, de primeira ordem, a 500°C. / [en] The kinetics of the carbochlorination of pure vanadium pentoxide (V2O5) by the treatment of a powdered mixture of V2O5 and graphite with chlorine gas, was investigated, using the termogravimetric method, in the temperature range of 350°C to 550°C. The effect of chlorination temperature, amount of reducing agent (graphite) and partial pressure of chlorine gas on the reation kinetics was studied. Regarding the influence of temperature on the reaction kinetics, the shrinking-core or topochemical model was used to explain the experimental results obtained during this study. The activation energy of the reaction, in the temperature range of 350 to 400°C, was 52 kJ, suggesting the chemical reaction as the rate controlling step, and, in the temperature range of 400 to 550°C, was 11 kJ, as the diffusion of the reacting gas (fluid-dynamic conditions) seems to be the limiting step. The effect of the amount of graphite, in the range of 17 to 30%, at the temperatures of 350°C and 500°C, leads to distinct reaction behaviors, distinguishing the predominance of different factors according to the case studied, such as the contact between the reacting solids, which acts in order to increase the reaction rate, and the excess of carbon amount or the difficult of penetration of the reacting gas, acting towards a reduction of the reaction rate. The reaction occurred to be about second-order with respect to Cl2, at the temperature of 350°C, and first-order, at 500°C.

MSc. (Applied Chemistry) / Remediation of POPs particularly the chlorinated compounds in water is therefore crucial. This research work describes the modification of polyethersulfone (PES) thin-film membrane composite (TFC) with functionalised carbon nanotubes (f-CNTs) using the phase invasion method. The oxidised CNTs were successfully decorated with Zero-Valent (ZV) Fe/Ni nanoparticles for the adsorption and degradation studies of polychlorinated organic pollutants (in this case the dichlorodiphenyltrichloroethanes (DDTs)). The in situ modification procedure was carried out using different quantities (0.04 wt%, 0.1 wt% and 0.2 wt%) of Fe/Ni-f-CNTs nanohybrids dispersed in a DMAc solution and dipping the polyethersulfone powder into a suspension containing the Fe/Ni-f-CNTs to form a nano-composite membrane. The formed composite membrane characteristics were investigated with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA) and X-ray diffraction spectroscopy (XRD). The incorporation of nanohybrid in the PES membrane was found to increase the surface smoothness and the hydrophilicity of the composites. In addition, there was an increase in the adsorption of DDTs with increase in the nano-hybrid loading as indicated by the adsorption studies using the Langmuir isotherm and Freundlich isotherm studies. The data obtained from the batch studies closely fitted with the Langmuir isotherm based on the characteristic parameter RL found to lie within the standard range 0 < RL < 1 .

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22841号 / 工博第4781号 / 新制||工||1748(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 伊藤 禎彦, 教授 米田 稔, 准教授 越後 信哉 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

While free (breakpoint) chlorination is widely utilized in humanitarian water treatment, a main challenge limiting its effective application is in determining the initial dose to satisfy both health requirements and aesthetic considerations (i.e. taste and odour). International guidelines and studies showed varying recommendations for the initial chlorine dose and many did not consider chlorine decay during water transportation and storage for up to 24 hours. The main objective of this thesis is to develop a tool for humanitarian staff to accurately determine the initial chlorine dose for achieving free chlorine residual (FCR) objectives with the limited instrumentation and information in the field. The first manuscript included in the thesis gathered and evaluated seven basic chlorine decay models’ applicability in humanitarian treatment contexts. All seven models were found able to accurately describe chlorine decay in water representative of humanitarian treatment contexts with more than half of the regression resulted in R2 over 0.95. However, each model had its own limitations, which were discussed. The second manuscript involved conducting extensive chlorine decay tests in water with different characteristics, explored the relationships between the estimated chlorine decay constant and several water parameters including pH, turbidity, ultraviolet absorption at 254 nm wavelength (UVA254), temperature and 30-minute chlorine demand. It was found that the UVA254 of water followed linear and exponential relationships with the decay constant in Feben and Taras’s empirical model and that in the first order model respectively. Arrhenius-type relations were verified between the decay constant and water’s temperature. A model developed to predict FCR decay in water with known 30-minute chlorine demand accurately predicted FCR level in synthetic water (with humic acid being the main constituent) but underpredicted FCR decay in water with additional chlorine consuming matter. Further research on additional chlorine decay mechanisms are needed to expand the applicability of the model. / Graduate / 2021-04-13

The research presented in this dissertation provides the results of a comprehensive assessment of the water treatment requirements for the City of Sarasota. The City’s drinking water supply originates from two sources: (1) brackish groundwater from the Downtown well field, and (2) Floridan surficial groundwater from the City’s Verna well field. At the time the study was initiated, the City treated the brackish water supply using a reverse osmosis process that relied on sulfuric acid for pH adjustment as a pretreatment method. The Verna supply was aerated at the well field before transfer to the City’s water treatment facility, either for softening using an ion exchange process, or for final blending before supply. For the first phase of the study to evaluate whether the City can operate its brackish groundwater RO process without acid pretreatment, a three-step approach was undertaken that involved: (1) pilot testing the plan to reduce the dependence on acid, (2) implementing the plan on the fullscale system with conservative pH increments, and (3) continuous screening for scale formation potential by means of a “canary” monitoring device. Implementation of the study was successful and the annual savings in operating expenditure to the City is projected to be about $120,000. From the acid elimination study, using the relationship between electrical conductivity in water and total dissolved solids in water samples tested, a dynamic approach to evaluate the performance of the reverse osmosis plant was developed. This trending approach uses the mass transfer coefficient principles of the Homogeneous Solution Diffusion Model. Empirical models iv were also developed to predict mass transfer coefficients for solutes in terms of total dissolved solids and sodium. In the second phase of the study, the use of nanofiltration technology to treat aerated Verna well field water was investigated. The goal was to replace the City’s existing ion exchange process for the removal of hardness and total dissolved solids. Different pretreatment options were evaluated for the nanofiltration pilot to remove colloidal sulfur formed during pre-aeration of the groundwater. Sandfilters and ultrafiltration technology were evaluated as pretreatment. The sandfilter was inadequate as a pre-screen to the nanofiltration pilot. The ultrafiltration pilot (with and without a sandfilter as a pre-screen) proved to be an adequate pretreatment to remove particulates and colloids, especially the sulfur colloids in the surficial groundwater source. The nanofiltration pilot, was shown to be an efficient softening process for the Verna well field water, but it was impacted by biofoulants like algae. The algae growth was downstream of the ultrafiltration process, and so chlorination was used in the feed stream of the ultrafiltration process with dechlorination in the nanofiltration feed stream using excess bisulfite to achieve stable operations. Non-phosphonate based scale inhibitors were also used to reduce the availability of nutrients for biofilm growth on the nanofiltration membranes. The combined ultrafiltration-nanofiltration option for treatment of the highly fouling Verna water samples is feasible with chlorination (to control biofouling) and subsequent dechlorination. Alternatively, the study has shown that the City can also more economically and more reliably use ultrafiltration technology to filter all water from its Verna well field and use its current ion exchange process for removal of excess hardness in the water that it supplies

No description available.

No description available.