The objectives of this study were to determine: (1) whether or not heterotrophic microorganisms exert an effect on the trihalomethane (THM) or total organic halogen (TOX) formation potentials of algal extracellular products (ECP), and (2) whether or not diurnal cycling of THM and TOX precursors occurs in vitro. These objectives were addressed through culture studies of heterotrophic microorganisms and pure algae from both the green and blue-green divisions. Culture conditions were varied to study different aspects of algal and bacterial interactions. Results from continuous light assays indicated that heterotrophs, grown in the same culture vessel with algae, affected an increase in the potential of chlorinated culture filtrate to form THMs. No significant changes in TOX-formation potential were observed. Heterotrophs grown in volumes of algal ECP (cell-free filtrates of algal cultures) used the algal-produced organic carbon as their sole carbon source. These microorganisms further reduced both the dissolved organic carbon (DOC) concentration and the concentration of the DOC fraction that reacted to form TOXs. The fraction which produced THMs was not reduced. Heterotrophic microorganism metabolic activity increased the rate at which THMs fanned from chlorinated algal ECP but did not alter the seven-day THM-formation potentials. Their activity also increased the initial rate of TOX formation, but decreased the seven-day formation potential of these compounds. Attempts to demonstrate diurnal cycling of the concentration of THM precursors and other halogenated organic precursors, a phenomenon previously demonstrated in a eutrophic reservoir, were unsuccessful. / M.S.

The molecular size, charge, and solubility, distributions of natural DOC in raw and treated surface waters were investigated to determine the types of organic compounds removed by coagulation and settling. The distribution of organic precursors that react with chlorine to form organic halide compounds was also determined, along with the reaction rates. DOC removal by coagulation was size dependent. Compounds over 5,000 d were readily removed while compounds under 1,000 d were largely unaffected. Acidic and basic molecules were precipitated much more effectively than neutral ones. Both hydrophilic and hydrophobic molecules were selectively removed compared to compounds of intermediate solubility. Two groups of organic halide precursors were identified. Fulvic acids had high specific organic halide yields, and fast reaction rates with chlorine, but could be effectively removed by coagulation. Nonpolar neutral compounds were lower in molecular weight, slower to react with chlorine, and produced less organic halide, but could not be precipitated by coagulation. / Ph. D. / incomplete_metadata

The Arctic has long been considered to be a pristine environment, far from population centers and pollution sources. The detection of synthetic organochlorine compounds in various elements of the Arctic food web has confirmed the global dispersion of pollutants, particularly of persistent compounds such as organochlorines and heavy metals. Levels of heavy metals, although elevated, appear to be naturally so throughout much of the Arctic. Arctic pollution is both a humanitarian and ecological concern. Many arctic coastal communities depend heavily on marine mammal fat for sustenance, and are therefore potentially exposed to high levels of organochlorines and some metals. From an ecological perspective, the structure of arctic food webs, the importance of lipid mobilization for winter survival, and the adaptive physiologies of arctic organisms may result in an enhanced response to contaminant exposure. This thesis assesses the exposure and effect of organochlorine and heavy metal exposure in inland freshwater ecosystems of Arctic Alaska, and evaluates the physiological response of arctic grayling to experimental polychlorinated biphenyl (PCB) exposure. / Graduation date: 1995

Mémoire (M.P.Aquat.)--Université du Québec à Chicoutimi, 1990. / Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--Oregon State University, 2011. / Printout. Includes bibliographical references (leaves 69-74). Also available on the World Wide Web.

M.Sc. / The contamination of water by toxic compounds is one of the most serious environmental problems today. These toxic compounds mostly originate from industrial effluents, agriculture runoff, natural sources (e.g. heavy metals in water from rocks and soil erosion) and human waste. The contamination, which is both “organic” and “inorganic” has an impact on the environment and human health. The demand for water and the pressure to re-use this valuable resource has increased the need for improved techniques and materials to remove pollutants from water. The Nanomaterials Science research group at the University of Johannesburg has focused on developing synthetic polymers that can be employed in water treatment and pollutant monitoring. Recently, cyclodextrins (CD) and carbon nanotubes (CNTs) have been included in polymers for this application. For example, CD-co-hexamethylene-/toluene-diisocyanate polyurethanes and CNT-modified equivalents have been developed and have been successfully applied in removing organic contaminants from water to very low levels.1 Calixarenes are synthetic analogues of cyclodextrins that can be exploited via chemical modification to express a range of properties. In the present study, calixarenes, thiacalixarenes and carbon nanotube-based polymeric materials incorporating these molecules have been synthesised, characterised and tested for removing both organic pollutants (such as p-nitrophenol) and inorganic pollutants (Cd2+, Pb2+) from water. Lead(II) and Cadmium(II) are a threat in South Africa because of their toxicity, and while p-nitrophenol is much less of a problem it represents a useful model organic pollutant. The absorption capacity of the polymers towards heavy metals and organic contaminants was tested by mixing the polymer with synthetic water containing known concentration of the contaminants at about 10 mg/L. Atomic absorption spectrometry (AAS) and ultraviolet-visible spectrometry (UV-vis) were used to determine the levels of heavy metals and organic contaminants, respectively. The target pollutants (Cd2+, 1 see KL Salipira MTech dissertation, University of Johannesburg 2008 Pb2+ and p-nitrophenol) were all successfully removed from water by the various polymers, however the degree of removal and loading capacities of the polymers differed. This information gives some insight into what functional components are needed for making successful adsorbents. It was observed, for example, that ptert- butylcalix[8]arene/hexamethylene diisocyanate (C8A/HMDI) had a higher adsorption capacity towards p-nitrophenol and Pb2+ than towards Cd2+, and also a higher capacity than the corresponding calix[4]arene polymers with smaller calixarene cavities.

No description available.

Submitted in fulfillment of the requirements of the Degree of Master of Technology: Chemistry, Durban University of Technology, 2014. / This project arose out the need for a simple method to analyse NOM on a routine basis. Water samples were obtained from the Vaal dam, which is one of the dams used by a hydroelectric power station. Analysis was preceded by separation of NOM into the humic and non-humic portions. The humic portion was separated into two fractions by employing a non-ionic resin (DAX-8) to separate humic acid from fulvic acid. High performance size exclusion chromatography (HPSEC), equipped with an Ultraviolet( UV) detector and an Evaporative Light Scattering (ELS) detector connected in series, was used to obtain molecular weight distribution information and the concentration levels of the two acids. Mixed standards of polyethylene oxide/glycol were employed to calibrate the selected column. Suwanee River humic acid standard was used as a certified reference material. The molecular weight distributions (MWDs) of the isolated fractions of humic and fulvic acids were determined with ELSD detection as weight-average (Mw), number-average (Mn) and polydispersity (ρ) of individual NOM fractions. The Mw/Mn ratio was found to be less than 1.5 in all the fractions, indicating that they have a low and narrow size fraction. An increase in Mn and Mw values, with increasing wavelength for all three humic substances (HS) examined was observed. The HS, isolated from the dam water, was found to be about the same molecular weight as the International Humic Acid Standard (IIHSS). For the fulvic acid standard, the molecular weight was estimated to be around 7500 Da. Characterization of NOM was done to assist in the identification of the species present in the water. FTIR-ATR was used to as a characterization tool to identify the functional groups in the structure of the humic and fulvic acid respectively present in the Vaal Dam. Analysis of the infrared (IR) spectra indicated that the humic acids of the Vaal dam have phenolic hydroxyl groups, hydroxyl groups, conjugated double bond of aromatic family (C=C), and free carboxyl groups. The isolation method has proved to be applicable and reliable for dam water samples and showed to successfully separate the humic substances from water and further separate the humic substances into its hydrophobic acids, namely, humic and fulvic acids. It can be concluded that the Eskom Vaal dam composes of humic substance which shows that the technique alone gives a very good indication of the characteristics of water. The HPSEC method used, equipped with UV and ELSD was able to identify the molecular weight range of NOM present in source water as it confirmed that the Eskom Vaal dam contains humic substances as humic acid and fulvic acid and these pose a health concern as they can form disinfectant byproducts in the course of water treatment with chemicals. FTIR characterization was successful as important functional groups were clearly assigned. Lastly, the use of the TOC and DOC values to calculate SUVA was also a good tool to indicate the organic content in water. It is recommended to use larger amounts of water must be processed to obtain useful quantities of the humic and fulvic acid fractions.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology, 2016 / Natural organic matter if not removed from water used for electricity generation has dire consequences that affect the long term plant health. The main problem is that organic matter at higher temperature and pressure disintegrate into smaller organic acids and carbon dioxide. This causes the cycle water and steam to be acidic and this can result in corrosion of the plant. The raw water from the Komati (Arnot power station) and Usutu (Kriel power station) scheme were analysed to determine the organic profile and seasonal variation. There was a noticeable variation in the quality of the water with an increase in DOC during rainy season. The water was found to be containing hydrophobic as well as hydrophilic molecules that could be quantified with a liquid chromatography organic detector (LC-OCD). Current water treatment processes employed at the two stations, Arnot and Kriel, has demonstrated the capability of removing organics to just over 50 percent at the pre-treatment section. The water treatment plant includes demineralisation plant that was able to produce water that met Eskom’s target specifications of less than 250 ppb DOC values. Qualitative and quantitative analysis of the steam-condensate water was done by use of an ion chromatography method. The determined organic anions were found to be acetates, formats and lactates.