No description available.

M.Tech. / A variety of fungal species belonging to the genera Aspergillus, Penicillium, Fusarium and Alternaria, Cladosporium are common contaminants of food commodities such as grains, cereals, seeds, nuts, and fruits. These fungal species in turn produce mycotoxins under favourable conditions as secondary metabolites, which have been recorded to have harmful effects in both animals and man. The concern for mycotoxin contamination of food commodities grown and produced in sub-Saharan Africa has grown considerably over the years with increased and improved strategies on mycotoxin monitoring. The aim of this project was to determine and evaluate the quality of food commodities grown and produced in selected rural areas of the southern part of Nigeria in relation to fungi and mycotoxins, evaluate the health implications of the mycotoxins, as well as, suggest possible solutions to reduce exposure of the population in these areas to fungi and mycotoxins in the food. This study was of much importance as the populace of these areas depend solely on the food commodities grown and produced in these areas. Ochratoxin A, aflatoxins, deoxynivalenol, fumonisins and zearalenone are major mycotoxins occurring naturally in most food commodities that have important health significances and as such, it was important to determine the exposure of people in this part of the country to these major mycotoxins. A total of 144 samples comprising of rice (41), maize (39), cocoa (39) and cocoa-based powder beverage (25) collected from the fields, markets and stores were screened for Aspergillus, Fusarium and Penicillium species producing mycotoxins using conventional methods and DNA sequencing which were preceded by serial dilution of samples on agar plates. Further analysis for mycotoxin extraction was done using multi-mycotoxin extraction, strong anion exchange columns and immunoaffinity columns, which was followed by identification and quantification via thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Mycological screening of samples showed incidences of various species of filamentous fungi including A. flavus, A. parasiticus, A. ochraceus, A. niger, F. verticillioides, F. proliferatum and F. graminearum, with highest incidences of A. flavus in rice (65.9%), F. verticillioides in maize (76.9%), A. flavus in cocoa (77.8%) and Cladosporium in cocoa-based powder beverages (32%). Mycotoxicological analysis showed occurrences of aflatoxins, ochratoxin A, zearalenone, fumonisins and deoxynivalenol in all food samples analysed with fumonisins, aflatoxins, ochratoxin A and deoxynivalenol prevalent in maize samples; ochratoxin A, aflatoxins and fumonisisn prevalent in rice samples; aflatoxins, ochratoxin A and fumonisins prevalent in cocoa samples and ochratoxin A, fumonisins and zearalenone prevalent in cocoa-based powder beverage samples. Levels of mycotoxin contamination varied from field to market place to storage with higher contamination of mycotoxins in samples from markets and store houses. In order to determine the health implications of the extracted mycotoxins, cytotoxicity analysis was done using MTT (methylthiozol tetrazolium)- assay on human blood lymphocytes and results showed a reduction in cell viabilities on cells exposed to extracts contaminated with mycotoxins at varying concentrations over 24hrs and 48hrs duration. It was seen that although levels of mycotoxins in samples were below and some above the set regulatory limits of mycotoxins in food, daily exposure to these mycotoxins over a long period of time could be dangerous health-wise influencing symptoms such as immunosuppression, kidney disorders, reproductive health disorders, liver and oesophageal cancers. It is therefore necessary to educate rural population and other populace on the health implications of ingesting these mycotoxins as well as teach them simple and cheap methods of preventing mycotoxin contamination of food commodities.

L'objectif de ce travail de thèse est d'évaluer les performances des systèmes proposés pour le contrôle en temps réel de la qualité d’eau dans le réseau d’eau potable. Il a été mené dans le cadre du projet européen SmartWater4Europeet du projet SunRise qui vise la construction d’un démonstrateur à grande échelle de la ville intelligente et durable sur le Campus de la Cité Scientifique. Le travail comporte 4 parties:La première partie présente une étude bibliographique des travaux réalisés sur le suivi en temps réel de la qualité de l’eau. Il présente les paramètres utilisés pour surveiller la qualité de l’eau et les technologies disponibles pour suivre ces paramètres.La seconde partie présente la construction d’un pilote en laboratoire pour l’analyse des performances des systèmes de contrôle de la qualité de l’eau et une description des systèmes utilisés (EventLab, s::can et Intellisonde). La troisième partie est consacrée à l’étude de l'efficacité du suivi du chlore pour la détection des contaminants microbiens. Les résultats montrent que le suivi du chlore constitue un outil efficace pour la surveillance de la qualité microbiologique de l'eau potable.La quatrième partie présente les réponses des systèmes utilisés à l’injection de contaminants. Les essais montrent une grande fiabilité d’EventLab et de S::can pour détecter les contaminants chimiques. Concernant les contaminants biologiques, s::can montre une capacité à détecter ces contaminants pour des concentrations bactériennes supérieures à 106UFC/ml.La dernière partie présente le réseau d'eau de la Cité Scientifique qui constitue le support du projet « SunRise». Les résultats des tests de contrôle de la qualité de l’eau sont présentés et analysés. On donne aussi la localisation des systèmes de contrôle de la qualité de l’eau qui seront installés sur le réseau d’eau. / The objective of this thesis is to evaluate the performance of systems proposed for real-time monitoring of water quality in the drinking water network. It was conducted within the European project SmartWater4Europe and SunRise project, which aims at the construction of a demonstrator of the smart city on the campus of the“Cité Scientifique”. The work consists of 4parts:The first part presents a literature review of the work conducted on the real-time monitoring of water quality. It shows the parameters used to monitor the water quality and the technologies available to monitor these parameters.The second part presents the construction of a Lab pilot for analyzing the performance of the water quality control systems. After a description of the systems used in this thesis(EventLab, s :: can and Intellisonde), we present the procedure followed for the realization of contaminant.The third part is devoted to the study of the performance of chlorine monitoring for detection of microbial contaminants. The results show that monitoring of chlorine constitutes an effective tool for monitoring the microbiological quality of drinking water.The fourth part presents the responses of EventLab and s::can to the injection of contaminants. Tests show a high reliability of EventLab and s::can to detect chemical contaminants. Regarding biological contaminants, s::can shows an ability to detect these contaminants for bacterial concentrations exceeding 106UFC/ml.The final part presents the water network of Cité Scientifique. The results of the water quality control are presented and analyzed. It also gives the location of the water quality control systems that will be installed on the water network.

Biogeochemical reactions and vadose zone transport, in particular gas phasetransport, are inherently coupled processes. To explore feedback mechanisms between these processes in a quantitative manner, multicomponent gas diffusion and advection are implemented into an existing reactive transport model that includes a full suite of geochemical reactions. Multicomponent gas diffusion is described based on the Dusty Gas Model, which provides the most generally applicable description for gas diffusion.Gas advection is described by Darcy's Law, which in the current formulation, is directly substituted into the transport equations. The model is used to investigate the interactions between geochemical reactions and transport processes with an emphasis to quantify reaction-induced gas migration in the vadose zone. Simulations of pyrite oxidation in mine tailings, gas attenuation in partially saturated landfill soil covers, and methane production and oxidation in aquifers contaminated by organic compounds demonstrate how biogeochemical reactions drive diffusive and advective transport of reactive and non-reactive gases. Pyrite oxidation in mine tailings causes a pressure reduction in the reaction zone and drives advective gas flow into the sediment column, enhancing the oxidation process. Release of carbondioxide by carbonate mineral dissolution partly offsets pressure reduction, and illustrates the role of water-rock interaction on gas transport. Microbially mediated methane oxidation in landfill covers reduces the existing upward pressure gradient, there by decreasing the contribution of advective methane emissions to the atmosphere and enhancing the net flux of atmospheric oxygen into the soil column. At an oil spill site, both generation of CH⁴ in the methanogenic zone and oxidation of CH⁴ in the methanotrophic zone contribute to drive advective and diffusive fluxes. The model confirmed that non-reactive gases tend to accumulate in zones of gas consumption and become depleted in zones of gas production. In most cases, the model was able to quantify existing conceptual models, but also proved useful to identify data gaps, sensitivity, and inconsistencies in conceptual models. The formulation of the model is general and can be applied to other vadose zone systems in which reaction-induced gas transport is of importance. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.

In March 1994, a report was issued to the Indiana Department of Environmental Management after Jim Allen Maintenance, Inc. found levels of total petroleum hydrocarbons (TPH) exceeding the level appropriate for action (100 parts per million) during an underground storage tank closure report assessment. Creek Run L.L.C Environmental Engineering was contracted by Jay Petroleum to complete an initial site characterization. Through quarterly monitoring of benzene, toluene, ethyl benzene, and methyl tert-butyl ether for 11 years, Creek Run L.L.C determined that biodegradation was occurring. Upon using BIOSCREEN, a contaminant transport modeling software that simulates natural attenuation over time, it was determined that the retardation factor was 1.4, and the biodegradation rate constant was 4.6 per year. This indicates that the contaminant migration is slow in comparison to groundwater flow, and the rate of biodegradation is at an appropriate value to allow natural attenuation to occur on its own.

No description available.

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.

Graduation date: 1968