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This research investigated the influence of bromide-ion concentrations upon trihalomethane (THM) formation and speciation. There is some speculation that bromide will increase the amount of THMs on a mass and/or molar basis. Previous research had indicated that bromide will affect the speciation to form the more brominated forms of THMs, but the extent of this speciation has not been clearly defined. Speciation is important when evaluating THM removal processes. The brominated species may require activated carbon for removal as opposed to air stripping for removal of the volatile species (chloroform). To investigate the role of bromide ion, a half-fractional, factorial matrix was used in which the DOC, pH, and temperature were varied at two levels; chlorine dosage and bromide-ion concentration were varied at three levels; and time was varied at five levels (up to six days). Over 750 experimental observations were used to generate five empirical models employing the six factors. An empirical model was generated to determine the mass for the THM species and to estimate the Total THMs. The results indicate the following: 1) all variables were positively correlated to trihalomethane formation; 2) bromide-ion concentration is a significant factor for each species; 3) bromide increased the THM yield both on a mass and a molar basis; and 4) bromide shifted the species distribution almost completely suppressing chloroform production in favor of the brominated THM species.

A pilot plant study was conducted in Newport News, Virginia to investigate the effectiveness of powdered activated carbon [PAC] and granular activated carbon [GAC], with and without preoxidation, for reducing trihalomethane [THM] precursor concentrations in Harwood's Mill Reservoir water. Preoxidation with ozone followed by GAC is referred to as the "biological activated carbon" [BAC] process. This study showed that the GAC and BAC processes obtained the same level of organic removal; however, BAC would provide longer bed life and require less carbon than the GAC process. PAC treatment of alum coagulated water provided significantly higher TOC and THMFP removals than alum coagulation alone. The use of a preoxidant (ozone) with PAC slightly improved the organic removal efficiency. While treatment by PAC increased THMFP removals, it was not as efficient as the GAC and BAC processes. UV absorbance measured at 254 nm and TOC were found to be good surrogates for THMFP in the GAC column, but not in the BAC column. / Master of Science

Two surface water sources in the southwestern United States, Colorado River Water (CRW) and California State Project Water (SPW), were studied in bench-scale experiments examining two Trihalomethane (THM) precursor removal processes, activated carbon adsorption and ozone oxidation. Both source water contained bromide (Br-) ion leading to brominated THMs upon chlorination. Activated carbon removed THM precursors, as measured by dissolved organic carbon (DOC), while having little effect on bromide. The net result was an increase in the ratio of Br-/DOC and an increase in the relative abundance of brominated THMs. Ozone oxidized higher molecular weight precursor molecules into lower molecular weight by-products which were less reactive with chlorine. Moreover, ozonation transformed Br- to hypobromous acid (an "in-situ" oxidant), leading to an increase in the percentage of brominated THMs.

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.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A formaÃÃo de trihalometanos na Ãgua de abastecimento humano representa um grande problema para a saÃde pÃblica, visto que esses compostos sÃo suspeitos de serem carcinogÃnicos. A tÃcnica referenciada para determinaÃÃo de trihalometanos na Ãgua à a cromatografia gasosa, onde se utiliza o detector de captura de elÃtrons. Essa tÃcnica apresenta algumas desvantagens que inviabilizam sua implantaÃÃo em uma estaÃÃo de tratamento de Ãgua (ETA). Um mÃtodo espectrofotomÃtrico desenvolvido pela empresa Hach pode auxiliar a operaÃÃo de uma ETA quanto ao monitoramento dos trihalometanos, pois esse mÃtodo analÃtico tem menor custo, uma resposta imediata dos resultados e à de fÃcil implantaÃÃo e operaÃÃo quando se compara com a cromatografia gasosa. Nesta pesquisa, foi realizada uma avaliaÃÃo do mÃtodo espectrofotomÃtrico comercial por alguns parÃmetros do Instituto Nacional de Metrologia, NormalizaÃÃo e Qualidade Industrial (INMETRO) e foi dividida em trÃs etapas. Na primeira etapa, realizou-se um teste para certificar-se que o agente redutor neutralizava todo o cloro residual presente na Ãgua. Foi adicionado tiossulfato de sÃdio na Ãgua final da ETA GaviÃo e determinou-se concentraÃÃo de âzeroâ mg L-1 na determinaÃÃo de cloro residual. A segunda etapa consistiu na implantaÃÃo e operaÃÃo da anÃlise de trihalometanos por cromatografia gasosa. Foram realizadas duas curvas utilizando dois padrÃes diferentes: um padrÃo de clorofÃrmio e um padrÃo de uma mistura contendo os quatro trihalometanos, todos com a mesma concentraÃÃo. Nessa etapa, todas as curvas construÃdas apresentaram um Ãndice de correlaÃÃo dentro da faixa exigida pelas normas do INMETRO e do mÃtodo. A terceira etapa consistiu na construÃÃo de curvas utilizando novamente os dois padrÃes, porÃm utilizando a tÃcnica espectrofotomÃtrica. Foram realizadas duas curvas de cada padrÃo pelo mesmo analista e uma curva de cada padrÃo por outro analista. Com os dados obtidos, estudou-se a precisÃo, exatidÃo, robustez, seletividade, linearidade, faixa de trabalho e faixa linear. AlÃm disso, foram realizados testes de adiÃÃo de padrÃo e um teste para verificar a interferÃncia de diferentes matrizes na anÃlise. Constatou-se que o mÃtodo nÃo apresentou precisÃo, nem exatidÃo. Pequenas mudanÃas realizadas no procedimento analÃtico causaram alteraÃÃo no resultado, indicando falta de robustez do mÃtodo analÃtico, alÃm de ser extremamente suscetÃvel a erros aleatÃrios e, possivelmente, quantificar outros subprodutos da desinfecÃÃo / The formation of trihalomethanes in human water supply represents a big problem to the public health, since these compounds are suspected carcinogens. The technique referred for determination of trihalomethanes in water is gas chromatography, which uses an electron capture detector. This technique has some disadvantages that unfeasible the implantation in the water treatment plant. A spectrophotometry method developed by Hach can assist the operation of a water treatment plant on the monitoring of trihalomethanes, since this analytical method has a lower cost, an immediate response by the results and is easy to implantation and operate when compared with gas chromatography. In this research, an evaluation of commercial spectrophotometry method was realized for some parameters of the Instituto Nacional de Metrologia, NormalizaÃÃo e Qualidade Industrial (INMETRO) and was divided into three stages. In the first stage, performed a test to make sure that the reducing agent neutralize any residual chlorine in the water. Sodium thiosulfate was added treated water of GaviÃoÂs water treatment plant, to determine the concentration of âzeroâ mg L-1 in the determination of residual chlorine. The second stage consists in the implantation and operation of the analysis of trihalomethanes by gas chromatography. Two curves were performed using two different standards: a standard of chloroform and a standard of a mixture containing the four trihalomethanes, all with the same concentration. At this stage, all curves constructed showed a correlation coefficient in the range required by the rules of the INMETRO and of the method. The third step was the construction of curves by using again the two standards, but using the spectrophotometric method. Two curves of each standard by the same analyst and a curve of each standard of the other analyst were performed. With the data obtained, was studied the precision, accuracy, robustness, selectivity, linearity, working range and linear range. In addition, a standard addition test and a test for interference in the analysis of different matrices were performed. It was found that the method no had precision and accuracy. Small changes made in the analytical procedure caused change in the result, indicating lack of robustness of the analytical method, besides being extremely susceptible to random errors and possibly quantify other disinfection byproducts

Bibliography: leaves 263-270.

Volcanic ash, pumice and Moringa oleifera (M. oleifera) were investigated as indigenous materials for removal of natural organic matter (NOM) at Kampala and Masaka water treatment plants in Uganda. Coagulation and filtration experiments were done using raw water at Kampala (Ggaba) and Masaka (Boma) National Water &amp; Sewerage Corporation water treatment plants. Assessment of the two plants was done and they were found to be faced with differing challenges given the nature of their raw water sources. Therefore, the study was conducted to seek appropriate treatment processes that suite the conditions at the respective plant and avoid or minimize formation of unwanted chlorination by-products. The results from the study indicated that there were both operational and design handicaps at the Ggaba treatment plant with a need to modify the filtration and clarification units. At Masaka, pre-chlorination led to increases in total trihalomethanes as high as 4000%. The characterization studies indicated the major fraction of NOM to be hydrophilic and there was no variation in the character of NOM along the unit treatment processes investigated. On the other hand experiments conducted at both the pilot and laboratory scale gave promising results. Simple horizontal flow roughing filter at Masaka gave rise to dissolved organic carbon (DOC) and ferrous iron removals of 27% and 89% respectively. With a combined use of pumice and hydrogen peroxide in the filter, DOC removals of up to 68% were achieved. The results from jar test experiments also indicated that use of alum with M. oleifera coagulant extracted with sodium chloride solution as coagulant aid is promising as a first stage in the treatment train for waters with a humic materials and high content of iron, typical of swamp water sources. Therefore the findings show that it is possible to avoid the formation of unwanted by-products by application of roughing filtration with hydrogen peroxide in place of the pre-chlorination process. Assessment of the characteristics of the volcanic ash showed that it meets the requirements for a filtration material; and results obtained from the pilot study showed that it was a suitable alternative material for use in a dual media filtration system. There was an increase in the filter run length of about two and half fold in the dual media filtration column compared to the mono medium column. / Vulkanaska, pimpsten och Moringa oleifera (M. oleifera) undersöktes som inhemska material for borttagande av naturligt organiskt material (NOM) i Kampala och Masaka reningsverk i Uganda. Koagulation och filtreringsexperiment gjordes med hjalp av råvatten i Kampala (Ggaba) och Masaka (Boma)reningsverk, som ingår i Nationella Vatten- och avloppsreningsverk, ett företag i Uganda. En bedömning av de två anläggningarna gjordes och det visade sig stå inför olika utmaningar på grund av de olika råvattnens karaktär. Den här studien genomfördes för att söka lämpliga processer för behandling av anpassade till förhållandena vid respektive anläggning samt för att undvika eller minimera uppkomsten av olika klorerade biprodukter. Resultatet från studien visade att det fanns problem både när det gäller design och arbetsrutiner på reningsverket Ggaba med ett behov att ändra filtrerings- och klarningsenheternaI Masaka ökade förkloreringsprocessen den totala mängden trihalometaner med 4000 %. Karakteriseringen av naturligt organiskt material (NOM) visade på en stor andel hydrofilt material och att ingen förändring av det organiska materialets karaktär skedde längs den undersökta processenheten. Å andra sidan visade både laboratorieförsök och experiment i pilotanläggningen att lovande resultat. Ett enkelt horisontellt flöde genom ett grovt filter i pilotanläggningen i Masaka resulterade i 89% mindre järn och 27% mindre NOM. Med en kombination av pimpsten och väteperoxid i filtret var avlägsnandet av löst organiskt material(DOC) från vattnet 68%. Resultaten från batchexperiment (jar test) i laboratoriet visade också lovande resultat för aluminium tillsammans med en koagulant extraherad med natriumklorid från Moringa oleifera (MOC-SC), som ett första steg för vatten från sumpmark med höga halter av järn och organiskt material. Således visar resultaten att det går att undvika bildandet av höga halter av trihalometan (THM) genom genom tillämpning av grovfitrering med väteperoxid i stället för förkloreringsprocessen. Utvärderingen av vulkanaskans egenskaper visade att vulkanaskan uppfyller kraven på ett filtermaterial och resultaten från pilotanläggningen visade att det är ett lämpligt material i ett filtreringssystem med två media. Den utnyttjade delen av filtret var 2,5 gånger längre i körningen med dubbla medier jämfört med ett medium. / <p>QC 20120910</p> / MAKERERE – Sida/SAREC RESEARCH COLLABORATION

The quality of drinking water effects not only human health, but also plays a decisive role in daily life. Although the Taiwan water corporation has improved water quality of Kaohsiung in recent years and most of the random testing results of the drinking water done by the EPB could meet the drinking water standards, many people still lack confidence in the tap water. This study (1) select 500 multi-unit residences from 11 districts in Kaohsiung and survey the water quality of the indirect water supply storage devices to understand the tap water quality of indirect water distribution network in Kaohsiung. (2) Aiming at the inhabitants living in multi-unit residences, a questionnaire about the satisfaction with the tap water in Kaohsiung is undergone by random sampling in order to understand the satisfaction with the tap water of the public. (3) The monitoring values of total trihalomethanes (TTHMs) in tap water distributional network in four seasons from December 2006 to September 2007 are used to analysis the seasonal changes, the equal concentration distribution figure, and the ration of all kinds of compounds of the THMs to the total amounts. The results of above analyses can be offered to Taiwan Water Corporation to make improvement and as the references of following studies. The result of the survey of satisfaction shows that 47% people incline to use tap water as drinking water¡F53% people don¡¦t have confidence in tap water and choose to the bottled water from water stations as drinking water source. 49.1% people living in cluster housing in Kaohsiung consider the quality of tap water common¡F15.4% people are satisfied with the tap water quality and 35.7% people are not satisfied with it. The main reason is the old pipelines, and the secondary reason is about the distasteful water. Most people wish to renew old pipelines as soon as possible, and give priority to strictly control the tap water quality. The analysis result of THMs concentrations shows that the average value of THMs in each district is highest in spring and lowest in autumn, especially in Cianjhen, Siaogang, and Cijin districts. The THMs concentration distribution of Cianjhen district is higher in the spring and winter. The proportion of CHCl3 (chloroform) to total amount of THMs is the highest in the water supply network, and it is also the major source of THMs.