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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Characterization of natural organic matter and trihalomethane formation potential for NOM fractions isolated from two surface water sources in Manitoba

Goss, Charles 19 January 2012 (has links)
The objective of this study was to evaluate the removal of natural organic matter (NOM) fractions, from the Portage la Prairie water treatment plant (PPWTP), which uses the Assiniboine River as a source, and the Morris water treatment plant (MWTP), which takes water from the Red River, to establish the NOM removal efficiency. The PPWTP sample set for total DOC removal by the plant found the granular activated carbon (GAC) filter was inefficiently removing dissolved organic carbon (DOC) from the water, often with concentrations increasing post-GAC. It was found that one sample set from the MWTP showed that NOM was not being removed by the nano filter with NOM increasing post-nano filtration, from 8.7mg/L to 10.2 mg/L. However, it was found that most of the time the nano filter was operating as manufacturer design showing a reduction of NOM post nano filter to <0.5mg/L.
2

Characterization of natural organic matter and trihalomethane formation potential for NOM fractions isolated from two surface water sources in Manitoba

Goss, Charles 19 January 2012 (has links)
The objective of this study was to evaluate the removal of natural organic matter (NOM) fractions, from the Portage la Prairie water treatment plant (PPWTP), which uses the Assiniboine River as a source, and the Morris water treatment plant (MWTP), which takes water from the Red River, to establish the NOM removal efficiency. The PPWTP sample set for total DOC removal by the plant found the granular activated carbon (GAC) filter was inefficiently removing dissolved organic carbon (DOC) from the water, often with concentrations increasing post-GAC. It was found that one sample set from the MWTP showed that NOM was not being removed by the nano filter with NOM increasing post-nano filtration, from 8.7mg/L to 10.2 mg/L. However, it was found that most of the time the nano filter was operating as manufacturer design showing a reduction of NOM post nano filter to <0.5mg/L.
3

Polysaccharide Materials and Sorption Studies of Chloroform and Total Trihalomethanes (TTHMs) in Aqueous Solution

2013 March 1900 (has links)
In this research, a series of synthetically engineered copolymers were synthesized containing polysaccharides (e.g., β-cyclodextrin and chitosan) to address the removal of trihalomethanes (THMs) from water environments. There are two main parts in this research thesis: i) the preparation and characterization of polysaccharide-based copolymers; ii) sorption studies of the copolymers with chloroform and total THMs (TTHMs) in aqueous solution. In the first part of this thesis, grafted polyester, polyester and grafted polyamide copolymers were prepared by cross-linking β-cyclodextrin (β-CD) and chitosan (CS) with various cross-linkers, including poly (acrylic acid) (PAA), terephthaloyl (TCl), and sebacoyl chloride (SCl), respectively. The synthesized copolymer materials were characterized by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), elemental (C and H) analyses, and NMR spectroscopy. Nitrogen porosimetry was used to analyze the surface area and pore structure characteristics of the copolymers and starting materials in solid state. The sorption properties of the copolymers in aqueous solution were studied using different dye probes (e.g., p-nitrophenol and methylene blue) by UV–Vis spectrophotometry. The copolymers showed markedly varied interactions with dye probes in accordance with their composition, surface area, and pore structure characteristics. Diverse materials were afforded by variation of the synthetic conditions. The sorption isotherms were evaluated with various isotherm models (e.g., Langmuir, BET, Freundlich and Sips). The Sips isotherm showed the best overall agreement with the experimental results and the sorption parameters provided estimates of the sorbent surface area and the sorption capacity for various copolymers in aqueous solution. The copolymer sorbents display tunable physicochemical properties according to the synthetic conditions. In the second part of this thesis, the direct aqueous injection (DAI) method with gas chromatography (GC) with electron capture or electrolytic conductivity detectors (ECD) enabled quantitative detection of chloroform and TTHMs in water. A preliminary adsorption study and kinetic study of chloroform provided the information to establish the experimental protocol for the sorption study. The sorption parameters were evaluated using the Sips model. The sorption capacity (Qm) values of chloroform for these synthetically engineered copolymers at similar conditions ranged from 0.00335-1.70 mmol/g. The relative ordering of the Qm values was observed: β-CD/PAA 1:5 > SCl-5 > SCl-10 ~ CP-1 > β-CD/PAA 1:10 > CP-5 > AC > β-CD/PAA 1:5 at high mixing speed. An extension of the sorption study for copolymers toward the multi-component THMs in water was carried out. The copolymers showed distinct adsorption capacities to THMs: chloroform (0.0485-0.287 mmol/g); DBCM (0.0712-0.277 mmol/g); BDCM (0.0684-0.387mmol/g); and bromoform (0.0522-1.07 mmol/g). The copolymers exhibited relatively high selectivity toward individual components of THMs due to their variable molecular size and polarizability. The copolymers showed favorable adsorption (e.g., β-CD/PAA 1:5, CP-1) and each type of polysaccharide (e.g., β-CD and CS) copolymers displays great potential for the removal of halomethane-based contaminants.
4

Removal of turbidity and organic matter from raw water using nonwoven and biofilter

Liao, Tzu-Hsiang 29 June 2011 (has links)
Extreme rainfall in raw water resource is greatly caused by climate change in Taiwan now. When typhoons are occurred, the turbidity in raw water is caused a high concentration frequently. In Taiwan the raw water, used by water treatment plants, comes from majorly river water. Most water treatment plants use chlorine disinfection; the disinfection process also produced excess disinfection by-products when raw water contains high turbidity and organic matter. In recent years, membrane method is widely being applied in water purification, but shortcomings were the higher price and not longer life. The purpose of this study is to investigate the treatment efficiency of turbidity, TOC, AOC, THMs and THMFP by using cheap nonwoven and biofilter (denoted as This System). In this study we used the base weight of 35 g/m2 nonwoven in filtration experiments for turbidity removal. Experimental results show turbidity removal by this system was nearly 90% when inlet turbidity is under moderate condition. The turbidity of treated water in effluent is all below 2 NTU that is compliance with national drinking water quality standards. Turbidity removal was about 90% using nonwoven with 21 pieces. Removal of organic matter is about 39% using biofilter when influent was in the low concentration of TOC. The removal rate is about 77% when the high TOC concentration in influent. In removal of TOC, TOC removal of raw water (I) was about 26.41%. The concentration of TOC was reduced from1169.9 £gg/L to 856.9£gg/L. The TOC removal of raw water (¢º) was about 19.65%. The concentration of TOC was reduced from 680.8£gg/L to 521£gg/L. The TOC removal of raw water (¢») was about 48.78%. The concentration of TOC was reduced from 1819 £gg/L to 936.5£gg/L. In removal of AOC, the removal rate of raw water (I) was about 50.83%. The concentration of AOC was from 59.51 £gg acetate-C/L to 28.42 £gg acetate-C/L). The removal of raw water (¢º) was about 50.97%. The concentration of AOC was from 73.08 £gg acetate-C/L to 35.8 £gg acetate-C/L. The removal of raw water (¢») was about 65.07%. The concentration of AOC was from 226.60 £gg acetate-C/L to 81.19 £gg acetate-C/L. The suggested limit level of AOC in treated water is 50£gg acetate-C/L Longer empty bed contact time of biofilter should enable the concentration below 50 £gg acetate-C/L. Removal of AOC increased with increased the empty bed contact time of biofilter . In removal of THMs and THMFP (denoted as precursors), the raw water (I) : THMs removal was about 50.22%. The concentration of THMs was reduced from 34.64 £gg/L to 17.56 £gg/L. The raw water (¢º): THMFP removal was about 46.83%. The concentration of THMs was reduced from 34.18 £gg/L to 18.27 £gg/L. The raw water (¢»): THMFP removal was about 51.81%. The concentration of THMFP was reduced from 81.49 £gg/L to 39.25 £gg/L. They were all lower than national standard of drinking water (THMs 80 £gg/L). Thus, this system can effectively remove turbidity, TOC, THMs and THMs precursors in raw water.
5

Investigação da toxicidade, tratabilidade e formação de subprodutos tóxicos em efluentes clorados de lagoas de estabilização com e sem pós-tratamento. / Investigation of toxicity, treatability and toxic disinfection by-products formation in chlorinated stabilization ponds effluents with and without post-treatment.

Léo, Luís Fernando Rossi 16 April 2008 (has links)
Entre as principais dificuldades que os sistemas de tratamento de esgotos domésticos compostos por lagoas de estabilização enfrentam para atender as exigências impostas pela Resolução CONAMA 357/2005 podem se destacar as concentrações elevadas de nitrogênio amoniacal, fósforo e coliformes fecais e totais. Estes últimos, quando os sistemas utilizam corpos receptores classe 2 ou 3 geram a necessidade de desinfecção. Dentre as diversas tecnologias disponíveis para a desinfecção dos esgotos, a cloração é bastante atrativa pelo custo reduzido, em relação às outras tecnologias, bem como pela elevada experiência que as companhias e municipalidades possuem neste tipo de sistema, advinda dos sistemas de tratamento de água. Dentre os sistemas de cloração, o uso de hipoclorito de sódio torna-se interessante pela segurança, simplicidade das instalações e de operação. A desvantagem do uso deste tipo de sistema se dá na possibilidade da formação de subprodutos tóxicos, dentro os quais pode-se destacar os trihalometanos (THMs) e os ácidos haloacéticos (AHAs), porém esta formação pode ser teoricamente reduzida pela presença de elevadas concentrações de nitrogênio amoniacal nos efluentes destes sistemas, por sua reação preferencial com o cloro, na formação de cloraminas. Outras possibilidades de redução na formação é reduzir a concentração de precursores, reduzir a dosagem de cloro e utilizar método de descloração dos efluentes após a desinfecção. Este trabalho, ambientado no desenvolvimento das pesquisas do Edital 4 do PROSAB/FINEP (Programa Nacional de Pesquisa em Saneamento Básico), desenvolveu testes de desinfecção em efluentes de lagoas anaeróbias e facultativas utilizando como desinfetante hipoclorito de sódio, em dosagens de 8,0 mgCl/L e 12,0 mgCl/L. Desenvolveu também testes de desinfecção com efluentes anaeróbios e facultativos pós-tratados por meio de coagulação/floculação/sedimentação e coagulação/floculação/flotação com ar dissolvido, com dosagens de 2,0 mgCl/L e 4,0 mgCl/L. Para todos os testes de desinfecção foram realizados também testes de descloração das amostras. Desta forma foi possível estudar, dentro de uma faixa limitada, as possibilidades de reduzir a formação de subprodutos tóxicos na desinfecção de efluentes de lagoas de estabilização com hipoclorito de sódio. Nas amostras foram determinados por meio de cromatografia gasosa as concentrações dos THMs e AHAs. Por meio das metodologias do Standard Methods 20th Edition foram realizadas as análises físico-químicas dos parâmetros pH, temperatura, DQO, DBO, Ntotal, N-NH3, NTK, cloro livre, cloraminas, coliformes e outros microrganismos indicadores. A formação de THMs se mostrou bastante pequena, em média abaixo dos 20,0 µg/L em todos os testes, aparentemente devido às elevadas concentrações de N-NH3, da ordem de 30,0 mg/L. O mesmo não ocorreu com os AHAs. Em muitos testes a concentração encontrada de AHAs totais superou o padrão de 80,0 µg/L preconizados pela USEPA para água potável, e aqui adotado como padrão comparativo. A descloração reduziu em média 52% a concentração de AHAs nos testes, colocando quase todas as amostras dentro do padrão de 80,0 µg/L. Os bioensaios mostraram que a presença de cloro livre nas amostras eleva a toxicidade aguda em Daphnia similis provocada pelos efluentes e que a cloração seguida de descloração produz efluentes com toxicidade inferior à toxicidade dos efluentes apenas clorados e toxicidade também inferior àquela dos efluentes sem cloração. / The main difficulties that the stabilization ponds for sewage treatment systems face to meet the requirements imposed by CONAMA Resolution 357/2005 can highlight the high concentrations of ammonia nitrogen, phosphorus and fecal and total coliform. When the systems use receivers water bodies Class 2 or 3 generate the need for disinfection. Among the different technologies available for the disinfection of sewage, the chlorination is very attractive at reduced cost compared to other technologies, as well as the high experience that companies and municipalities have in this type of system, because the water treatment systems. About the chlorination technologies, the use of sodium hypochlorite becomes interesting for security, simplicity of installation and operation. The disadvantage of using this type of system is given the possibility of formation of toxic by-products, within which you can highlight the trihalomethanes (THMs) and haloacetic acids (AHAs), but this formation can theoretically be reduced by the presence of high concentrations of ammoniacal nitrogen in effluents of these systems, for its preferential reaction with the chlorine in the formation of cloraminas. Other possibilities for reducing the training is to reduce the concentration of precursors (organic matter), reduce the dosage of chlorine and use dechlorination method after disinfection. This work, developed in PROSAB / FINEP (National Program for Research on Sanitation) research announcement number 4, developed tests for disinfection of anaerobic and facultative ponds effluents using sodium hypochlorite as a disinfectant, in concentrations of 8.0 mgCl/L and 12.0 mgCl/L. Were also developed tests for disinfection with anaerobic and facultative ponds effluents post-treated by coagulation / flocculation / sedimentation and coagulation / flocculation / flotation with dissolved air, with concentrations of 2.0 mgCl/L and 4.0 mgCl/L. For all of disinfection tests were also conducted dechlorination tests. This made it possible to study the possibilities of reducing the formation of toxic byproducts of the stabilization ponds effluents disinfection with sodium hypochlorite. The THMs and AHAS concentrations were determined by gas chromatography. Through the methods of Standard Methods 20th Edition analyses were carried out physical-chemical parameters of pH, temperature, COD, BOD, total nitrogen, ammoniacal nitrogen, total Kjeldhal nitrogen, free chlorine, chloramines, coliforms and other indicator microorganisms. The formation of THMs was very low, on average below the 20.0 µg/L in all tests, apparently due to high concentrations of NH3-N, the order of 30.0 mg/L. The same did not occur with AHAs. In many tests found concentrations of AHAs exceeded the standard of 80.0 µg/L recommended by the USEPA for drinking water. Dechlorination reduced 52% of AHAs concentrations, in average. Bioassays showed that the presence of free chlorine in the samples increase the acute toxicity in Daphnia similes. Chlorination followed by dechlorination produces effluents with less toxicity than the toxicity of chlorinated and effluent without chlorination.
6

Prediction of THMs formation in water distribution system of Downtown Kaohsiung City

Shin, Jian-Ming 09 July 2012 (has links)
Chlorine is always used in disinfection process of water treatment plant (WTP) in Kaohsiung, and the major of disinfection by-products (DBPs) is THMs. Reaction of THMs producing were found in relation to lots of factors of water quality. Therefore we used SPSS to analysis the relation between water quality and THMs content for making prediction model of THMs formation in water distribution system in downtown Kaohsiung city. It is expected to estimate the concentration of THMs with a simple method, and to reduce THMs by controlling some items of water quality. While the variance of TOC value is low, we found that concentration of THMs is related to temperature, pH, and residual chlorine by regression method. In these items, residual chlorine had the highest correlation. While the variance of TOC value is high, the correlation between the three items and THMs is weaker than the front one. From this finding, TOC is best one fitting factor in prediction of THMs. In this study, we found that R-square value of Multivariate regression prediction is higher than the value of Univariate regression prediction probably for THMs producing is a complex reaction, so formation model was hard using only one item of water quality.
7

Survey on Satisfaction of Indirect Water Supplies in A Distribution System and Varriation of THMs Concentration in Kaohsiung City

Huang, Hsiu-fang 15 July 2008 (has links)
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.
8

Determination Of Thmfp Of The Reservoirs In Turkey : Kinetics Aspect

Artug, Mine 01 November 2004 (has links) (PDF)
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.
9

Investigação da toxicidade, tratabilidade e formação de subprodutos tóxicos em efluentes clorados de lagoas de estabilização com e sem pós-tratamento. / Investigation of toxicity, treatability and toxic disinfection by-products formation in chlorinated stabilization ponds effluents with and without post-treatment.

Luís Fernando Rossi Léo 16 April 2008 (has links)
Entre as principais dificuldades que os sistemas de tratamento de esgotos domésticos compostos por lagoas de estabilização enfrentam para atender as exigências impostas pela Resolução CONAMA 357/2005 podem se destacar as concentrações elevadas de nitrogênio amoniacal, fósforo e coliformes fecais e totais. Estes últimos, quando os sistemas utilizam corpos receptores classe 2 ou 3 geram a necessidade de desinfecção. Dentre as diversas tecnologias disponíveis para a desinfecção dos esgotos, a cloração é bastante atrativa pelo custo reduzido, em relação às outras tecnologias, bem como pela elevada experiência que as companhias e municipalidades possuem neste tipo de sistema, advinda dos sistemas de tratamento de água. Dentre os sistemas de cloração, o uso de hipoclorito de sódio torna-se interessante pela segurança, simplicidade das instalações e de operação. A desvantagem do uso deste tipo de sistema se dá na possibilidade da formação de subprodutos tóxicos, dentro os quais pode-se destacar os trihalometanos (THMs) e os ácidos haloacéticos (AHAs), porém esta formação pode ser teoricamente reduzida pela presença de elevadas concentrações de nitrogênio amoniacal nos efluentes destes sistemas, por sua reação preferencial com o cloro, na formação de cloraminas. Outras possibilidades de redução na formação é reduzir a concentração de precursores, reduzir a dosagem de cloro e utilizar método de descloração dos efluentes após a desinfecção. Este trabalho, ambientado no desenvolvimento das pesquisas do Edital 4 do PROSAB/FINEP (Programa Nacional de Pesquisa em Saneamento Básico), desenvolveu testes de desinfecção em efluentes de lagoas anaeróbias e facultativas utilizando como desinfetante hipoclorito de sódio, em dosagens de 8,0 mgCl/L e 12,0 mgCl/L. Desenvolveu também testes de desinfecção com efluentes anaeróbios e facultativos pós-tratados por meio de coagulação/floculação/sedimentação e coagulação/floculação/flotação com ar dissolvido, com dosagens de 2,0 mgCl/L e 4,0 mgCl/L. Para todos os testes de desinfecção foram realizados também testes de descloração das amostras. Desta forma foi possível estudar, dentro de uma faixa limitada, as possibilidades de reduzir a formação de subprodutos tóxicos na desinfecção de efluentes de lagoas de estabilização com hipoclorito de sódio. Nas amostras foram determinados por meio de cromatografia gasosa as concentrações dos THMs e AHAs. Por meio das metodologias do Standard Methods 20th Edition foram realizadas as análises físico-químicas dos parâmetros pH, temperatura, DQO, DBO, Ntotal, N-NH3, NTK, cloro livre, cloraminas, coliformes e outros microrganismos indicadores. A formação de THMs se mostrou bastante pequena, em média abaixo dos 20,0 µg/L em todos os testes, aparentemente devido às elevadas concentrações de N-NH3, da ordem de 30,0 mg/L. O mesmo não ocorreu com os AHAs. Em muitos testes a concentração encontrada de AHAs totais superou o padrão de 80,0 µg/L preconizados pela USEPA para água potável, e aqui adotado como padrão comparativo. A descloração reduziu em média 52% a concentração de AHAs nos testes, colocando quase todas as amostras dentro do padrão de 80,0 µg/L. Os bioensaios mostraram que a presença de cloro livre nas amostras eleva a toxicidade aguda em Daphnia similis provocada pelos efluentes e que a cloração seguida de descloração produz efluentes com toxicidade inferior à toxicidade dos efluentes apenas clorados e toxicidade também inferior àquela dos efluentes sem cloração. / The main difficulties that the stabilization ponds for sewage treatment systems face to meet the requirements imposed by CONAMA Resolution 357/2005 can highlight the high concentrations of ammonia nitrogen, phosphorus and fecal and total coliform. When the systems use receivers water bodies Class 2 or 3 generate the need for disinfection. Among the different technologies available for the disinfection of sewage, the chlorination is very attractive at reduced cost compared to other technologies, as well as the high experience that companies and municipalities have in this type of system, because the water treatment systems. About the chlorination technologies, the use of sodium hypochlorite becomes interesting for security, simplicity of installation and operation. The disadvantage of using this type of system is given the possibility of formation of toxic by-products, within which you can highlight the trihalomethanes (THMs) and haloacetic acids (AHAs), but this formation can theoretically be reduced by the presence of high concentrations of ammoniacal nitrogen in effluents of these systems, for its preferential reaction with the chlorine in the formation of cloraminas. Other possibilities for reducing the training is to reduce the concentration of precursors (organic matter), reduce the dosage of chlorine and use dechlorination method after disinfection. This work, developed in PROSAB / FINEP (National Program for Research on Sanitation) research announcement number 4, developed tests for disinfection of anaerobic and facultative ponds effluents using sodium hypochlorite as a disinfectant, in concentrations of 8.0 mgCl/L and 12.0 mgCl/L. Were also developed tests for disinfection with anaerobic and facultative ponds effluents post-treated by coagulation / flocculation / sedimentation and coagulation / flocculation / flotation with dissolved air, with concentrations of 2.0 mgCl/L and 4.0 mgCl/L. For all of disinfection tests were also conducted dechlorination tests. This made it possible to study the possibilities of reducing the formation of toxic byproducts of the stabilization ponds effluents disinfection with sodium hypochlorite. The THMs and AHAS concentrations were determined by gas chromatography. Through the methods of Standard Methods 20th Edition analyses were carried out physical-chemical parameters of pH, temperature, COD, BOD, total nitrogen, ammoniacal nitrogen, total Kjeldhal nitrogen, free chlorine, chloramines, coliforms and other indicator microorganisms. The formation of THMs was very low, on average below the 20.0 µg/L in all tests, apparently due to high concentrations of NH3-N, the order of 30.0 mg/L. The same did not occur with AHAs. In many tests found concentrations of AHAs exceeded the standard of 80.0 µg/L recommended by the USEPA for drinking water. Dechlorination reduced 52% of AHAs concentrations, in average. Bioassays showed that the presence of free chlorine in the samples increase the acute toxicity in Daphnia similes. Chlorination followed by dechlorination produces effluents with less toxicity than the toxicity of chlorinated and effluent without chlorination.
10

Monitoring of fouling and clean-in-place (CIP) using the Rotoscope and microscopy and monitoring of trihalomethanes (THMs) produced from electro chemically activated (ECA) water during CIP

Mashangoane, Boitumelo Francina 07 February 2012 (has links)
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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