A comprehensive literature survey looking at different aspects of organic contaminants in sewage sludge is incorporated in the thesis. It is clear from the data available that plants do not take up most of the organic pollutants. However, a risk of contamination of the food chain exists when sludge is spread directly onto crops that are to be consumed raw or semi-cooked. The major source of human exposure to sludge-borne organic pollutants is through the consumption of animal products such as meat and milk through the bioaccumulation of compounds such as polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), polychlorinated biphenyls (PCBs) or polynuclear aromatic hydrocarbons (PAHs). This is due to the ingestion of soil and sludge by livestock due to the spreading of sludge on the land used for grazing. Currently little is known about the plant uptake of phthalates and nonylphenols, which are present in relatively high levels in sludge. Included in the literature survey is a list of the most common methods normally used for extraction of organic compounds and the possible methods of analysis. What is noted is that there is no universally accepted and validated analytical method for analysing most of the organic compounds. In addition, data concerning levels of organic pollutants is scarce worldwide. The methods selected for this project were EPA Methods 35IOC (Liquid-liquid extraction) and 3540C (Soxhlet extraction) for the aqueous and solid sewage sludge respectively. These two methods were chosen because they are simple, inexpensive and effective. The chosen purification method was the sulfur clean-up process (EPA Method 3660B). This is because sulfur precipitates were observed in most of the concentrated extracts, especially from the solid samples. A total of 109 samples from 78 sewage works were extracted, using Soxhlet extraction for solids and liquid-liquid extraction for liquid samples. All the extracts were analysed using GC-MS. The identification of the organic compounds was made possible by the use of GC-MS Wiley library. A total of 712 organic compounds were identified in the South African sewage sludge. These included Phenols, Pesticides, PAHs, Phthalates, PCBs, Furans, Amines, Aldehydes, Esters, Acids, Chlorinated Hydrocarbons, Alcohols, Hydrocarbons and Others (all sorts of organic compounds that did not belong to the named categories). The extraction efficiency and reproducibility using a "clean" sludge matrix was carried out. The results showed that the method chosen for extraction i.e. Soxhlet method had an efficiency of over 80% and the results were reproducible. A total of 14 samples were selected for the quantification of p-cresol, nonylphenol and pesticides listed in the current legislation. The results showed negative results for pesticides, confirming that the pesticides listed in the legislation are not the compounds that need to be regulated as far as organic pollutants are concerned. The reasons for this are most likely due to the fact that most of the pesticides listed are banned or their use is severely restricted. The results for the quantification of p-cresol and nonylphenol, when comparing the liquid and the solid extracts of the liquid sludge, show that 99% of p-cresol is concentrated in the liquid phase. The opposite is true when looking at nonylphenol where 90% of it is trapped in the solid matrix leaving 10% in the liquid phase. It is also noted that liquid sludge contains high concentrations of both p-cresol and nonylphenol when compared to the solid sludge. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Orientador: Luíz Vicente de Andrade Scalvi / Banca: Valmor Roberto Mastelaro / Banca: Joelma Perez / Banca: Fenelon Martinho Lima Pontes / Banca: Luiz Henrique Dall'Antonia / Resumo: Os semicondutores BiVO4 e NiO vem sendo bastante estudados nos últimos anos para aplicação em fotoeletrocálise, mais especificamente na degradação de poluentes orgânicos em meio aquoso, implicando em sustentabilidade ambiental. Neste trabalho, estes materiais foram obtidos na forma de filmes finos pelas técnicas: Síntese de Combustão em Solução e Co-precipatação, combinadas ao processo de deposição via molhamento (dip-coating). A composição, microestrutura e morfologia dos filmes foram avaliadas por TG-DTA, DTX e MEV. Os resultados de TG-DTA e DRX permitiram verificar a temperatura de formação das classes desejadas, 287ºC para o BiVO4 e 305ºC NiO. Imagens MEV mostram que os filmes são compostos por partículas de formato aproximadamente eférico, com boa dispersão sobre o suporte. Espectros UV-VIS mostraram que filmes de BiVO4 absorvem na região do visível com bandgap da ordem de 2,5 eV, e filmes de NiO absorvem no ultravioleta no ultravioleta com bandgap da ordem de 3,0 eV. A caracterização elétrica, trouxe resultados surpreendentes, particularmente no filme de NiO, onde iluminação com luz de energia acima do gap aumentou a resistividade do material, o que está ligado a variâncias de Ni2+. A caracterização eletroquímica, realizada por voltametria cíclica e cronoamperometria, mostrou que ambos os filmes respondem à excitação à excitação com luz de determinado comprimento de onda, além de apresentar estabilidade na corrente fotogerada. Ambos os filmes se mostraram eletroativos frente à reação de degradação do azul de metileno, sendo que na presença de luz ocorre a maior degradação. Um eletrodo com heterojunção p-n foi confeccionado utilizando estes dois materiais. O eletrodo FTO/p-NiO/n-BiVO4 apresentou excelente desempenho frente à degradação do azul de metileno, em... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The semiconductor BiVO4 and NiO have been extensively studied in recent years for the photoelectrocatalysis application, more specifically in the organics polluants degradation in aqueous solution, which leads to sustainability environment. In this work, these materials were obtained in the form of thin films by Solution Combustion Systhesis and co-precipitation techniques, combinee with the dip-coating deposition process. The composition, microstructure and morphology of these films was evaluated by TG-DTA, XRD and SEM. TG-DTA and XRD results were important to verify the temperature of the desired phase formation, which tuned out as 287ºC and 305ºC for the BiVO4 and NiO, respectively. SEM images show that the films consist of spherical particles with good dispersion on the support . UV-VIS Spectroscopy, have shown that BiVO4 thin film absorbs in the viable region with bandage energy of about 2.5 eV, whereas the NiO thin film absorbs in the ultraviolet region with bandagap energy about 3.0 eV. The electrical characterization has shown striking results, particularly on the NiO film, where irradiation with above bandgap light leads to a resistivity increase, which was related to the presence of Ni2+ vacancies. The electrochemical characterization, carried out by cyclic voltammetry and chronoamperometry, has shown that both the films respond to excitation with light of specific wavelength and provides stability in the photocurrent. Both the films are electroactive in the methylene blue dedradation reaction and that the greatest degradation takes place in the presence of light. A p-n heterojunction electrode was made using these two materials. The FTO/p-NiO/n-BiVO4, electrode showed excellent performance in the methylene blue degradation in different electrolytes under visible and UV light ilumination. The percentages of... (Complete abstract click electronic access below) / Doutor

Studying the interactions between bacteria and soil colloidal particles in the environment is important for bioaugmentation purposes. Different factors affect the transport of the bacteria in porous media. For example, the soil type, the ionic strength of the substrate, and biological properties, such as the bacterial cell motility. Since organic materials are present in almost all subsurface media, the presence of natural organic matter (NOM) is considered an important factor influencing bacterial transport in porous media. In this work, a model system was developed to examine the interactions between natural colloidal particles and environmental bacteria using Atomic Force Microscopy (AFM). The natural colloids in the environment were modeled by a surface film of adsorbed NOM onto spherical SiO2 particles. Poly(methacrylic acid) (PMA), a simple linear polyelectrolyte, was used to mimic NOM since both are dominated by carboxylic acid functional groups. Soil Humic Acid (SHA) and Suwannee River Humic Acid (SRHA), two acidic polyelectrolytes, were used in further experiments to represent more complicated NOM. A smooth strain of Pseudomonas aeruginosa (PAO1) that coexpresses A-band and B-band polysaccharides, and its rough mutant (AK1401) that only expresses the A-band polysaccharides, were chosen to represent environmental bacteria. The model system was characterized through analysis of the measured forces between the chemically-modified colloidal probes and the bacterial cells. Interestingly, we found that PMA was not a good model for the more complex NOM substances. Differences were also observed in how each bacterium interacted with the three forms of NOM. For example, P. aeruginosa PAO1 had the highest adhesion with both complex forms of NOM, while P. aeruginosa AK1401 had the lowest adhesion with the complex forms of NOM. Since the lipopolysaccharide (LPS) structure is the only difference between the two strains, we attribute the different interactions to differences in LPS structure. The polymer density on the bacterial surface was found to be the most important factor in controlling the nature of the interaction forces.

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Abstract not available

Thesis (M.Eng.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 130-137.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 148-158). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.