Issues of Disinfection By-Product (DBP) formation in response to chlorination in drinking water treatment systems is a common issue encountered by WTP operators. Efforts to minimize DBP formation are complicated by the presence of zebra mussels, which may inhabit the raw water intake of WTPs. While chlorination at the intake to control zebra mussel populations is effective, the formation of DBPs is exacerbated. Methods for reducing DBPs are explored, including adjusting the location for chlorine additions in the treatment sequence. Multivariate models for Total Trihalomethane (TTHM) and Haloacetic Acid (HAA) subspecies are employed to show that in some instances pre-chlorination can be reduced to lower DBP formation, while post-chlorination can be increased. A Regression model (R2 of 0.75) predicts that DBP levels can be lowered by post-chlorination rather than pre-chlorinating raw water for portions of the year except during the combatable life stage to assist in zebra mussel control. A second multivariate regression model for TTHM (R2 = 0.91) which includes bromide, a variable which, due to lack of data, was previously unused, is described and demonstrates that DBP levels can be reduced by lowering pre-chlorination levels. Finally, a Bayesian network is developed using the Webweavr-IV Toolkit, utilizing causal relationships between raw water quality parameters in the form of conditional probabilities. The results show that the average cancer risk can be decreased by while still maintaining zebra mussel control and simultaneously decreasing the incremental cancer risk, which currently fluctuates between 1 in 50,000 to 100,000 in Ontario. / Canada Research Chair Program, Ontario Research Foundation

Source water quality plays a critical role in maintaining the quality and supply of drinking water, yet it can be negatively affected by human activities. In Pennsylvania, coal mining and treatment of conventional oil and gas drilling produced wastewaters have affected source water quality for over 100 years. The recent unconventional natural gas development in the Marcellus Shale formation produces significant volumes of wastewater containing bromide and has the potential to affect source water quality and downstream drinking water quality. Wastewater from coal-fired power plants also contains bromide that may be released into source water. Increasing source water bromide presents a challenge as even small amounts of bromide in source water can lead to carcinogenic disinfection by-products (DBPs) in chlorinated finished drinking water. However, bromide is not regulated in source water and is not removed by conventional drinking water treatment processes. The objective of this work is to evaluate the safe bromide concentration in source water to minimize the cancer risk of trihalomethanes - a group of DBPs - in treated drinking water. By evaluating three years of water sampling data from the Monongahela River in Southwestern Pennsylvania, the present analysis reached three conclusions. First, bromide monitoring for source water quality should be taken at drinking water intake points. Water sample types (river water samples vs drinking water intake samples) can lead to different water quality conclusions and thus affect regulatory compliance decision-making. Second, bromide monitoring at drinking water intake points can serve as a predictor for changes in heavily brominated trihalomethanes concentrations in finished water. Increasing bromide in source water can serve as an early warning sign of increasing formation of heavily brominated trihalomethanes and their associated cancer risks in drinking water. Finally, this work developed a statistical simulation model to evaluate the effect of source water bromide on trihalomethane formation and speciation and to analyze the changing cancer risks in water associated with these changing bromide concentrations in the Monongahela River. The statistical simulation method proposed in this work leads to the conclusion that the bromide concentration in source water must be very low to prevent the adverse health effects associated with brominated trihalomethanes in chlorinated drinking water. This method can be used by water utilities to determine the bromide concentration in their source water that might indicate a need for process changes or by regulatory agencies to evaluate source water bromide issues.

Chlorine is still the most commonly used disinfectant in many water treatment plants all over the World. However, studies conducted demonstrated that the chlorine reacts with the natural organic matter (NOM) in source waters, and leads to the formation of a variety of chlorinated organic compounds, disinfection by-products (DBPs). Among these, the most common are the trihalomethanes (THMs). In this study, kinetics of the THM formation was investigated. Kinetic experiments were carried out with the raw waters from Devege&ccedil / idi and Atat&uuml / rk Reservoirs as well as with water containing a model compound, humic acid. THM and Chlorine concentrations were measured for 6 weeks on a seasonal basis. The simulation model developed by USEPA was used for predicting THM concentrations. The results of this study have shown that THM formation increases with increasing time and higher chlorine doses result in higher THM formation. Also, higher organic matter concentrations resulted in higher chlorine demands and both these parameters increased the TTHM concentrations. But, on the contrary to the standard THMFP testing, THM formation did not complete in seven days. In addition, THM formation and chlorine consumption were very rapid during the first 24 hr followed by a more gradual formation and decay after 24 hr. THM formation rates ranged between 35-66 &micro / g/L.day for Atat&uuml / rk Reservoir, between 80-167 &micro / g/L.day for Devege&ccedil / idi Reservoir and between 85-248 &micro / g/L.day for humic acid during the first 24 hr, and ranged between 2-6 &micro / g/L.day for Atat&uuml / rk Reservoir, between 7-16 &micro / g/L.day for Devege&ccedil / idi Reservoir and between 3-14 &micro / g/L.day for humic acid after 24 hr.

abstract: Disinfection byproducts are the result of reactions between natural organic matter (NOM) and a disinfectant. The formation and speciation of DBP formation is largely dependent on the disinfectant used and the natural organic matter (NOM) concentration and composition. This study examined the use of photocatalysis with titanium dioxide for the oxidation and removal of DBP precursors (NOM) and the inhibition of DBP formation. Water sources were collected from various points in the treatment process, treated with photocatalysis, and chlorinated to analyze the implications on total trihalomethane (TTHM) and the five haloacetic acids (HAA5) formations. The three sub-objectives for this study included: the comparison of enhanced and standard coagulation to photocatalysis for the removal of DBP precursors; the analysis of photocatalysis and characterization of organic matter using size exclusion chromatography and fluorescence spectroscopy and excitation-emission matrices; and the analysis of photocatalysis before GAC filtration. There were consistencies in the trends for each objective including reduced DBP precursors, measured as dissolved organic carbon DOC concentration and UV absorbance at 254 nm. Both of these parameters decreased with increased photocatalytic treatment and could be due in part to the adsorption to as well as the oxidation of NOM on the TiO2 surface. This resulted in lower THM and HAA concentrations at Medium and High photocatalytic treatment levels. However, at No UV exposure and Low photocatalytic treatment levels where oxidation reactions were inherently incomplete, there was an increase in THM and HAA formation potential, in most cases being significantly greater than those found in the raw water or Control samples. The size exclusion chromatography (SEC) results suggest that photocatalysis preferentially degrades the higher molecular mass fraction of NOM releasing lower molecular mass (LMM) compounds that have not been completely oxidized. The molecular weight distributions could explain the THM and HAA formation potentials that decreased at the No UV exposure samples but increased at Low photocatalytic treatment levels. The use of photocatalysis before GAC adsorption appears to increase bed life of the contactors; however, higher photocatalytic treatment levels have been shown to completely mineralize NOM and would therefore not require additional GAC adsorption after photocatalysis. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2011

abstract: Granular activated carbon (GAC) is effectively used to remove natural organic matter (NOM) and to assist in the removal of disinfection byproducts (DBPs) and their precursors. However, operation of GAC is cost- and labor-intensive due to frequent media replacement. Optimizing the use of GAC is necessary to ensure treatment efficiency while reducing costs. This dissertation presents four strategies to reduce improve GAC usage while reducing formation of DBPs. The first part of this work adopts Rapid Small Scale Tests (RSSCTs) to evaluate removal of molecular weight fractions of NOM, characterized using size exclusion chromatography (SECDOC). Total trihalomethanes (TTHM), haloacetic acids (HAA5) and haloacetonitriles (HAN) formation were quantified after treatment with GAC. Low MW NOM was removed preferentially in the early bed volumes, up until exhaustion of available adsorption sites. DBP formation potential lowered with DOC removal. Chlorination prior to GAC is investigated in the second part of this work as a strategy to increase removal of NOM and DBP precursors. Results showed lower TTHM formation in the effluent of the GAC treatment when pre-chlorination was adopted, meaning this strategy could help optimize and extend the bed life if GAC filters. The third part of this work investigates in-situ GAC regeneration as an alternative to recover adsorption capacity of field-spent GAC that could potentially offer new modes of operation for water treatment facilities while savng costs with reactivation of spent GAC in an external facility. Field-spent GACs were treated with different oxidant solutions and recovery in adsorption capacity was evaluated for NOM and for two micro pollutants. Recovery of GAC adsorption capacity was not satisfactory for most of conditions evaluated. This indicates that in-situ GAC regeneration could be more effective when the adsorbates are present at high concentrations. Lastly, this work investigates the impact of low molecular weight polyDADMAC on N-nitrosodimethylamine (NDMA) formation. Water treatment facilities rely on polyDADMAC as a coagulant aid to comply with NOM removal and turbidity requirements. Since polymer-derived NDMA precursors are not removed by GAC, it is essential to optimize the use and synthesis of polyDADMAC to reduce NDMA precursors during water treatment. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2017

No Brasil, a desinfecção e oxidação da água para o abastecimento público, são usualmente feitas com a adição de cloro nas formas de gás cloro, hipoclorito de sódio e hipoclorito de cálcio. A presença de substâncias húmicas em águas destinadas ao abastecimento público tem ocasionado diversos problemas, decorrentes da formação de subprodutos orgânicos halogenados, principalmente quando se emprega o cloro na oxidação e desinfecção da água. Alguns destes subprodutos são compostos carcinogênicos, como é o caso dos trialometanos. Avaliou-se neste estudo a formação de trialometanos em ensaios de ciclo completo, coagulação, floculação, sedimentação, filtração e pós-cloração, com e sem o uso da pré-oxidação com cloro e dióxido de cloro. A água de estudo utilizada nos ensaios foi preparada utilizando água de poço artesiano da Escola de Engenharia de São Carlos - Universidade de São Paulo, com adição de substâncias húmicas aquáticas extraídas de água coletada do rio Itapanhaú - Bertioga/SP, filtradas em membrana de 0,45µm, resultando cor verdadeira de 100uH. Foi estudada também, a influência do tipo de coagulante, sulfato de alumínio e cloreto férrico, na eficiência de remoção das substâncias húmicas aquáticas por meio de ensaios de coagulação, na qual foram determinadas as dosagens e o pH de coagulação a serem utilizadas nos ensaios finais de ciclo completo. O cloreto férrico teve um desempenho superior ao do sulfato de alumínio, principalmente nas velocidades de sedimentação mais altas. Isso se deve ao fato da floculação da água coagulada com o cloreto férrico ter gerado flocos de tamanhos superiores aos gerados com o sulfato de alumínio, e isso fez com que houvesse maior eficiência na sedimentação. O cloreto férrico, por esse motivo, foi o coagulante usado nos ensaios finais de ciclo completo, os quais foram feitos com e sem o uso da pré-oxidação com cloro e dióxido de cloro. As amostras foram coletadas em todas as etapas do tratamento e nos tempos de contato de 0,5 e 24h após o término da pós-cloração para a avaliação da formação de trialometanos. Os trialometanos foram identificados e quantificados por cromatografia gasosa com detector de captura de elétrons (CG-DCE) e os resultados analíticos demonstraram que os ensaios de ciclo completo com pré-oxidação, com dióxido de cloro e com coagulante foi eficiente na redução da formação de trialometanos se comparado com os ensaios de ciclo completo com pré-oxidação com cloro. Os resultados também demonstraram que nos ensaios de ciclo completo sem pré-oxidação houve uma menor formação de trialometanos se comparados com os ensaios de ciclo completo com pré-oxidação. Foi observada a formação de clorofórmio em todas as amostras de água de estudo em uma faixa de concentração de 2,6 a 29,1µg L-1. / In Brazil, the water supply disinfection and oxidation is by means of chlorine addition in the form of chlorine gas, sodium hypochlorite and calcium hypochlorite. The presence of humic substances in the drinking water supply has caused many problems due to the formation of halogenated organic by-products, especially when it uses chlorine in the water oxidation and disinfection. Some of these by-products are carcinogenic substances, as for instance trihalomethanes. This study assessed the formation of trihalomethanes in complete test cycles, coagulation, flocculation, sedimentation, filtration and post-chlorination, with and without the use of the preoxidation with chlorine and chlorine dioxide. The water used in the tests was prepared using artesian well water at the School of Engineering of São Carlos - University of São Paulo, with the addition of aquatic humic substances extracted from the Itapanhaú river (Bertioga, SP, Brazil), resulting in a true color of 100uH. The influence of the type of coagulant, aluminum sulphate and ferric chloride was also studied for the efficiency of removing aquatic humics substances by means of coagulation tests, which determined the dosages and coagulation pH to be used in the final complete cycle tests. The ferric chloride indicated a superior performance when compared to aluminum sulphate, mainly in higher settling velocities. This is due to the fact that flocculation of the coagulated water with ferric chloride generated bigger floc sizes than that generated with aluminum sulphate, hence giving rise to greater sedimentation efficiency. Thus, ferric chloride was the used coagulant in the complete cycle final tests, which were used with and without the preoxidation with chlorine and chlorine dioxide. The samples were collected throughout the treatment stages and in the contact times of 0.5 and 24h at the conclusion of after-chloration, in order to evaluate the formation of trihalomethanes. The trihalomethanes were identified and quantified by gas chromatography with electron capture detector (GC-ECD) and the analytical results demonstrated that the complete cycle tests with daily preoxidation, with chlorine dioxide and with coagulant were efficient in the reduction of trihalomethane formation, when compared to the complete cycle tests with daily chlorine preoxidation. The results also demonstrated that in the complete cycle tests without daily preoxidation there was a decrease in trihalomethane formation, when compared to complete cycle tests with daily preoxidation. The chloroform formation was observed in all the studied water samples in a concentration band of 2.6 to 29.1?g L-1.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of chlorine and other compounds to treat water for human consumption has attracted the attention of the scientific community, due to reactions with natural organic matter (NOM) that could generate subproducts undesirable from the human health perspective. The trihalomethanes (THMs) are frequently found in water treatment systems, with chloroform (CHCl3), dichlorobromomethane (CHBrCl2), dibromochloromethane (CHBr2Cl) and bromoform (CHBr3) being the most common. Alternative adsorbents for removal of these compounds are sought, that are economically viable, easily disposed of and readily regenerated without losing their properties. The objective of the present work was to assess the performance of batch and fixed bed column systems, using humin in natura and immobilized on sodium silicate, respectively, for adsorption of the principal THMs found in water supply systems, as well as to determine the regeneration capacity of humin following thermal desorption. Kinetically, adsorption of THMs by humin followed a pseudo-second order reaction, with more than 50 % removal in the first 5 minutes for all compounds studied, and equilibrium described by the Freundlich model reached in 240 minutes. The THM adsorption results were significant at p < 0.05 for both batch (74.6 83.2 % removal) and column (99.7 % removal in optimized tests) experiments, and were significantly (p < 0.05) influenced by flow rate and bed height. The potential of humin for removal of the THMs was confirmed in thermal desorption tests, when increases in adsorption capacity (significant at p < 0.05) of 18.88 % (CHBr3), 18.09 % (CHBr2Cl), 24.16 % (CHBrCl2), 20.15 % (CHCl3) and 24.16 % (total trihalomethanes) were observed 17 between the first and fifth uses of the same adsorbent bed. The results demonstrate the potential of humin for removal of THMs. / A utilização de cloro e outros compostos nas Estações de Tratamento de Água para consumo humano têm atraído a atenção da comunidade científica devido as suas reações com a matéria orgânica natural (MON) as quais podem gerar subprodutos indesejáveis na perspectiva da saúde humana. Os trihalometanos são frequentemente encontrados nos sistemas de tratamento de água, sendo os mais comuns o clorofórmio (CHCl3), diclorobromometano (CHBrCl2), dibromoclorometano (CHBr2Cl) e bromofórmio (CHBr3). Adsorventes alternativos são pesquisados para remoção desses compostos, os quais sejam economicamente viáveis, de fácil disposição e que possam ser facilmente regenerados sem perda das suas propriedades. Assim, o objetivo do presente trabalho foi avaliar a performance da adsorção em batelada e em coluna de leito fixo usando humina in natura e imobilizada em sílica de sódio, respectivamente, na adsorção dos principais trihalometanos (THM) encontrados no sistema de abastecimento de água, bem como avaliar a capacidade de regeneração da mesma após a dessorção térmica. Cineticamente, a adsorção dos THM por humina pode ser descrita pelo modelo de pseudo segunda ordem, com capacidade de remoção de mais de 50% nos primeiros cinco minutos para todos os compostos em estudo. O modelo da isoterma de Freundlich foi o que melhor se ajustou com tempo de equilíbrio de 240 min. Os resultados da adsorção dos THM foram significativos p<0,05 para os ensaios em batelada (74,6-82,2% de remoção) e em coluna (99,7% de remoção para os testes otimizados), sendo influenciado significativamente pelo fluxo e altura do leito adsorvente. Os ensaios de dessorção térmica 15 comprovaram o potencial da humina na remoção dos THM, devido ao aumento significativo p<0,05 de 18,88, 18,09, 24,16, 20,15 e 24,16% para o CHBr3, CHBr2Cl, CHBrCl2, CHCl3 e trihalometanos totais respectivamente, na capacidade de adsorção da humina entre primeiro e o quinto ciclo de reuso do leito. O trabalho demonstra o potencial da humina na remoção de THM.

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.

The unwanted occurrence of biofilms in various industries requires critical remedial action in order to prevent their detrimental effects which potentially result in huge economic losses. Adequate monitoring of biofilms is a powerful tool to aid their thorough understanding and ultimate control. The Rotoscope is an instrument based on the principle of light absorption and reflection that was used in this study to monitor and study biofilms. Biofilm development of cocci and bacilli species was monitored using the Rotoscope and microscopy. Light reflectance decreased over time as the biofilm developed. Information on the different stages of biofilm development could also be deduced from light reflectance assays of the Rotoscope. Microscopy validated results which were obtained from light reflectance assays. Information on the morphology of the bacteria, depth of the biofilm as well as the different stages of biofilm development was deduced from EM and CLSM images. The Rotoscope was an easy, effective, on-line monitoring device for the development of biofilms. It was a lso showed to be useful in coll ecting informati on to help characterize bacteria species present within a biofilm The Rotoscope was integrated into a simulated soft drink (SO) production line to monitor biofouling and the efficacy of a clean-in-place (CIP) regime using electrochemically acti vated (ECA) water. During CIF the Catholyte and Anolyte (components of ECA) were effective as detergent and disinfectant respecti vely. This was indi cated by results obtained from microbial analysis of removable slides from the MPD, microscopic analysis, as well as pH, ORP and EC analysis. The absence of microbial growth and soil on microscope slides from the Rotoscope were a good indication of the high efficacy of Catholyte and Anolyte (components of ECA) as detergent and disinfectant respectively in a crp system. In addition, the re latively constant values reported for pH, ORP and EC before and aft er CIP suggests that the Catholyte and Anolyte were effective during CIF. The effect of Anolyte on trihalomethane (THM) formation was observed because of the presence of chl orine compounds. Low levels of THMs were obtained from CIP effluent which provided a good indicati on that Anolyte is an environmentally friendly alternative disinfectant compared to conventional disinfectants currently used in CIP. Increased pH and the presence of bromide resulted in an overall increase of THMs in systems using dissolved organic carbon (DOC) models (Glucose, maltose and phenol). There was however variation in the amount of THM produced using the three DOC models. The differences were attributed to the composition of organic matter in particular the aromacity and the nature and position of the functional groups of the model DOCs. / Dissertation (MSc)--University of Pretoria, 2012. / Microbiology and Plant Pathology / unrestricted

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