Jagals, P., Prof. du Preez, H.H., Prof.

Since Actinomycetes have been isolated from finished public drinking water, it is believed that the organisms are unaffected by the chlorination and flocculation of water treatment plants and pass as spores through the filters into the general distribution system. For this reason it was deemed imperative to study the toxic effects of these organisms.

No description available.

Escherichia coli (E. coli) is a gram-negative bacteria found in the intestinal system of humans that can also contaminate food, drinking water, as well as lakes and rivers. While not all strains are pathogenic, some including O157:H7 can cause severe illness. Conventional methods of detecting E. coli contamination in water samples often have limitations for on-site testing applications, which can include their slow detection time or need for expensive laboratory equipment. While several fluorescent biosensors for the detection of E. coli have been developed in the Didar lab, there is increased interest in colourimetric biosensors whose signal can be interpreted with the naked eye. This thesis will describe the development and performance of a hydrogel biosensor, that is made of polyacrylamide chains crosslinked by an E. coli detecting Deoxyribozyme (DNAzyme) and its substrate. In the presence of E. coli, the DNAzyme cleaves its substrate and crosslinking breaks down, resulting in the visible dissolution of the hydrogel. Paired with the use of bacteriophage induced cell lysis to amplify the target protein, detection sensitivity to the order of 10^1 CFU/mL has been achieved using this platform with an incubation time of 18 hours. A convolutional neural network (CNN) trained on optical images of the platform was able to classify samples as contaminated or uncontaminated with a validation accuracy of over 93%. / Thesis / Master of Applied Science (MASc) / Microbial contamination of water sources including surface water, groundwater, and drinking water can pose risks to human health. One bacterial species that can sometimes contaminate these sources is Escherichia coli (E. coli). To determine if E. coli is present in a water sample, it often needs to be sent to a laboratory for testing, which can be time consuming and inconvenient. Therefore, researchers are working to develop new sensors that are able to detect E. coli from water samples, ideally being simple enough to use that testing could be done right away and without sending the sample to another location. In this research project, we have developed a new biosensor that can detect E. coli in water samples. To use the sensor, a water sample is added onto a small red gel in a tube, and this gel breaks apart if E. coli is present in the sample.

No description available.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2018. / Trihalomethanes (THMs) are a group of four compounds that are formed, along with other disinfected by-products. This happens when chloride or other disinfectants are used to control microbial contamination in drinking water, which then reacts with natural organic or inorganic substances in water. Trihalomethanes are better known by their common names such as chloroform, bromodichloromethane, chlorodibromomethane and bromoform. These four compounds are known to be classified as cancer group B carcinogens (shown to cause cancer in laboratory animals). Trihalomethane levels tend to increase with pH, temperature, time and the level of “precursors" present. Precursors are known to be organic substances which react with chloride to form THMs. One significant way of reducing the amount of THMs in water is to eliminate or reduce chlorination before filtrations and reduce precursors. There are guideline limits for THMs in the SANS 241:2015 document, but they are not continuously monitored and their levels in natural water are not known. The aim of this study is to develop a rapid, fast and reliable liquid-liquid microextraction technique, to determine the presence of THMs in natural water sources. This study particularly focuses on different water sources e.g. river, underground, borehole and chlorinated water. Chlorinated water is the water that has been presumably treated for bacteria and fungus growth. The results that were obtained for chlorinated water are as follow, 10.120 μg/L − 11.654 μg/L for chloroform, 2.214 μg/L - 2.666 μg/L for bromodichloromethane, 0.819 μg/L − 0.895 μg/L chlorodibromomethane and 0.103 μg/L - 0.135 μg/L for bromoform from validation data. All these THMs concentrations have been found to be below the SANS 241:2015 limits. Natural water shows a very high affinity for chloroform. This is what is expected under normal conditions as chloroform is the most abundant THM of all THMs present in natural water. The liquid-liquid microextraction technique that was optimized and used for the determination of THMs in this study is a rapid, simple and inexpensive technique that provides low limits of detection (LOD) e.g. 0.1999 μg/L chlorodibromomethane and 0.2056 μg/L bromoform and wide dynamic range (LOQ) of 0.6664 μg/L chlorodibromomethane and 0.6854 μg/L bromoform for the determination of THMs.

Contamination of drinking water with metals is a major problem facing many areas of United States and the World. There is a need for an inexpensive remediation technology for the removal of metals in drinking water that can be applied to small rural water systems. This research will focus on the development of a process for removal of select metals from drinking water by limestone-based material. Metals in drinking water considered for this research include lead and selenium. Limestone-based material has demonstrated the potential to reduce select metals (lead, cadmium and arsenic) in drinking water, with the additional benefit of low-cost disposal of a stable waste product in ordinary landfills. Earlier research by the principal investigators using limestone-based material for drinking water treatment has clearly shown that this material can achieve metals removal of greater than 90 percent. This project will investigate techniques to improve removal efficiency of limestone-based material through adsorption and precipitation. This research will assist in the development of a granular adsorbent product that will remove metals and that can be manufactured and sold for use at the drinking water source, at point-of-use, or at point-of entry.

INTRODUCTION: Syndromic surveillance is a method of rapid disease detection based on categories of syndromes, or signs, experienced before the full onset of disease. It is increasingly being used by government agencies and health departments to identify disease outbreaks in a timely manner. Environmental exposures are known to induce respiratory and gastrointestinal symptoms, tend to have a seasonality component, and adversely affect the health of millions of people. OBJECTIVE: In this study, we assess the availability of environmental exposure data for air pollution (PM2.5, ozone, and NO2), pollen, and water contaminant exposure for use in a syndromic surveillance project. We also evaluate: 1) the general proximity of HMO populations to monitors, and 2) distribution of SES characteristics of the area populations with respect to monitor locations. METHODS: We collected exposure data, patient population data, and Census tract SES data for two metropolitan areas where Kaiser Permanente (KP) provides medical services: Atlanta, Georgia and the northern Virginia, District of Columbia (DC), and Baltimore area. Exposure data for air pollution and pollen were collected for 2013-2014. Straight-line distance from a monitor to the nearest KP clinic, and from each Census tract centroid, to the nearest air pollution or pollen monitor was computed using the Euclidean distance formula. RESULTS: Air pollution is routinely monitored by a Federal mandate, is universally available, and easily obtained. Pollen data is collected by private entities, which in some cases hinders access. Water quality data is generally publically available, but it is collected at the source and not easily traceable to water delivery endpoints. In both Atlanta and DC, Maryland, and Virginia most of the clinics (78% and 94%, respectively) are located within 10 miles of an air pollution monitor; approximately 83% and 94% of the KP populations were located within 10 miles of an air pollution monitor. SES populations differ substantially by race, age, income, and education with respect to the nearest monitor. However, the median and interquartile range of various air pollutants does not differ much across the monitors – indicating that, on average, there is little SES gradient in type of level of air pollution exposure. CONCLUSIONS: Overall, this study adds knowledge regarding future considerations about the coverage of environmental monitors and to what extent exposure measure estimates can be assigned to certain populations located near monitors.

A <i>Pseudomonas</i> sp. capable of degrading tertiary butyl alcohol (TBA) as a sole carbon source, was isolated from a groundwater aquifer (50 ft. deep) at a petroleum refinery. The most probable number (MPN) of TBA degrading microorganisms was 4.9 x 10³ organisms/g (dry wt) of subsurface soil. Pristine subsurface soils, which did not have a history of petroleum contamination, had MPNs of < 2 TBA degrading organisms/g (dry wt) indicating a natural enrichment process at the refinery site. The Q_O2 of <i>Pseudomonas</i> sp. was 4.2 ml O₂/mg dry wt/h when TBA was the substrate. The optimum pH for growth was 7.0. The organism grew faster in continuous culture when TBA was the sole carbon source with a doubling time 33.6 h. The doubling time in batch culture was 112.3 h. When yeast extract was added to a mineral salts + TBA medium to concentrations greater than 1 mg/ml, TBA degradation was inhibited. When the yeast extract concentration was 0.1 mg/ml, a diauxy effect was seen in the growth rate. This suggested that TBA degradation by <i>Pseudomonas</i> sp. was subject to a regulatory mechanism. / M.S.

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2018-04-10T23:17:52Z No. of bitstreams: 1 Disserta??o_Janderson_Versao_Final.pdf: 7521820 bytes, checksum: 18fa39470356e8c8276a28e568152e4c (MD5) / Made available in DSpace on 2018-04-10T23:17:52Z (GMT). No. of bitstreams: 1 Disserta??o_Janderson_Versao_Final.pdf: 7521820 bytes, checksum: 18fa39470356e8c8276a28e568152e4c (MD5) Previous issue date: 2017-03-31 / Water is essential for the maintenance of life, however, environmental pollution has been causing the loss of the quality of water resources, affecting not only the life of living beings. The reservoirs represent the main source of water to supply the demands of the Brazilian Northeast. However, the quality of stored water has suffered from the effects of anthropic activities makes it compromised for human consumption, animal and for irrigation. In this context, the present work aimed to elaborate a case study on water quality in semi-arid regions, not for human consumption, specifically in the Sisal Identity Territory, having as main study area the main public dams in the municipality of Teofil?ndia-BA. In order to meet the proposed objective, a mapping of the main water bodies of the municipality of Teofil?ndia-BA was carried out, using images from Landsat 8 satellite, OLI sensor of 2014, orbit 216/68 by supervised classification. Subsequently, fieldwork was carried out consisting of three (3) campaigns for the collection of surface water, occurring in the period of May (pre-rain), June (post-rain) and November (dry). The physico-chemical parameters and metals analyzed were: Temperature, Salinity, Chloride, pH, OD, BOD, COD, Turbidity, Temotolerant Coliforms, Cadmium, Lead, Copper, Chromium, Manganese, Nickel and were compared with the standards established by Resolution N? 357 / 2005 of the National Environmental Council - CONAMA. In the evaluation of the results of the Land Use Use map, it was verified that the agricultural culture class predominates in the region with about 44,46%, permanent agriculture (agave) covers 10,72%. The area used with the vegetation (caatinga) is representative, totaling 17,15%. The exposed soil class represents 6,64% and 8,82% of the shade classes. The identifiable water bodies in the satellite image represent 0,16% and 12,05% of urban area. The accuracy of the mapping for the water bodies, provided by the Tau index, was 0,70. Regarding the results of the water quality evaluation of the three public dams located near the urban perimeter in the municipality of Teofil?ndia-BA during the three campaigns, it was possible to observe that the concentrations of Chloride, Electrical Conductivity, OD, BOD, COD and Thermotolerant Coliforms presented Variations that exceeded the limits established by current legislation. As for the evaluated metals, only Cd was not detected at any point and sampled period. There were no, in their greatest majority, correlation between the variable studies. In the pre-rain period the trend of contamination in the water followed the decreasing order: Ni> Pb> Mn> Cr, in the post-rain: Ni> Pb> Mn> Zn and not dry: Ni> Pb> Cu> Zn. From the data presented, it can be inferred that the main source of pollution of the waters of the dams is derived from anthropogenic origin, mainly by agricultural activities and insufficient sewage network. / A ?gua ? essencial para a manuten??o da vida, entretanto, a polui??o ambiental vem causando a perda da qualidade dos recursos h?dricos, afetando n?o apenas a vida dos seres vivos. Os a?udes representam a principal fonte de ?gua para suprir as demandas no semi?rido do nordeste brasileiro. No entanto, a qualidade da ?gua armazenada tem sofrido os efeitos provenientes das atividades antr?picas tornando-a comprometida para o consumo humano, animal e para irriga??o. Nesse contexto, o presente trabalho elaborou um estudo de caso sobre a qualidade da ?gua, n?o para suprimento humano, em regi?es semi?ridas, especificamente no Territ?rio de Identidade do Sisal, tendo como ?rea de estudo os principais a?udes p?blicos no munic?pio de Teofil?ndia-BA. Para atender o objetivo proposto foi realizado um mapeamento dos principais corpos de ?gua do munic?pio de Teofil?ndia-BA, utilizando imagens do sat?lite Landsat 8, sensor OLI do ano de 2014, ?rbita 216/68 por meio da classifica??o supervisionada. Posteriormente foram realizados trabalhos de campo constando de 3 (tr?s) campanhas de coleta de ?guas superficiais, ocorridas no per?odo de maio (pr?-chuva), junho (p?s-chuva) e novembro (seco). Os par?metros f?sico-qu?micos e metais analisados foram: Temperatura, Salinidade, Cloreto, pH, OD, DBO, DQO, Turbidez, Coliformes Termotolerantes, cadmio, chumbo, cromo, cobre, mangan?s, n?quel e zinco foram comparados com os padr?es estabelecidos pela Resolu??o N? 357/2005 do Conselho Nacional de Meio Ambiente ? CONAMA. Na avalia??o dos resultados do mapa de Uso Ocupa??o do Solo verificou-se que a classe da cultura agropecu?ria predomina na regi?o com cerca de 44,46%, a agricultura permanente (agave) abrange, 10,72%. A ?rea utilizada com a vegeta??o (caatinga) ? representativa totalizando 17,15%. A classe solo exposto representa, 6,64% e 8,82% das classes sombras. Os corpos d??gua identific?veis na imagem de sat?lite representam 0,16% e 12,05% de ?rea urbana. A acur?cia do mapeamento para os corpos d??gua, fornecida pelo ?ndice Tau, foi de 0,70. Com rela??o ao resultado da avalia??o da qualidade da ?gua dos tr?s a?udes p?blicos localizados pr?ximo ao per?metro urbano no munic?pio de Teofil?ndia-BA durante as tr?s campanhas, foi poss?vel observar que as concentra??es de Cloreto, Condutividade El?trica, OD, DBO, DQO e Coliformes Termotolerantes apresentaram varia??es de valores que excederam os limites estabelecidos pela legisla??o vigente. Quanto aos metais avaliados somente o Cd n?o foi detectado em nenhum dos pontos e per?odos amostrados. N?o houve, em sua grande maioria, correla??o entre as vari?veis estudadas. No per?odo pr?-chuva a tend?ncia de contamina??o na ?gua seguiu a ordem decrescente: Ni>Pb>Mn>Cr, no p?s-chuva: Ni>Pb>Mn>Zn e no seco: Ni>Pb>Cu>Zn. A partir dos dados apresentados, pode-se inferir que a principal fonte poluidora das ?guas dos a?udes ? proveniente de origem antropog?nica, principalmente por atividades agropecu?rias e insufici?ncia de uma rede de esgotamento sanit?rio.