Thesis (M.A.)--University of Toledo, 2010. / Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Arts Degree in Geography." "A thesis entitled"--at head of title. Title from title page of PDF document. Bibliography: p. 76-82.

Thesis (M.Sc.)--University of Hong Kong, 1996. / Includes bibliographical references. Also available in print.

Dissertation submitted in compliance with the requirements of the Master's Degree in Technology in Biotechnology, Durban Institute of Technology, 2003. / The measured kinetics of a bacterial culture degrading a single organic compound as a sole carbon source in a batch reactor depends on the history of the culture, the identifiability of the parameters, and the manner in which the experiment to measure them is run. The initial substrate to biomass ratio (So/Xo) used in the experiment is particularly important because it influences both parameter identifiability and the expression of the culture history. / M

Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Durban Institute of Technology, 2004. / M

M.Sc. (Chemistry) / In this study the stability as well as the fate and behavior of ZnO engineered nanoparticles (ENPs) in municipal wastewater systems were investigated. The first part of the study examined the influence of pH and ionic strength on the stability of ZnO ENPs in domestic wastewater to elucidate the dynamic changes on the ENPs physicochemical characteristics (e.g. aggregation or dissolution). The ZnO ENPs obtained commercially were characterized using transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), dynamic light scattering (DLS), BET surface area determination, and energy dispersive X-ray spectrometry (EDS). Results derived from inductively coupled plasma optical emission spectrometry (ICP-OES) for zinc analysis indicated a decrease on the released zinc concentration from wastewater as the pH and ionic strength increased. Conversely, an increase on zinc concentration from the sludge was observed. The findings suggest the removal of ZnO ENPs from the influent wastewater as the sludge settled out, and the removal efficiency was directly proportional to ionic strength and pH. In addition, the ZnO ENPs suspension in the wastewater was used to monitor the particle size distribution using the dynamic light scattering analysis (DLS). The formation of agglomerates was observed which the TEM and EDS analysis confirmed to be ZnO aggregates. The distribution of zinc in the sludge was investigated using XRD analysis and the findings indicated partial sedimentation of ZnO ENPs as the sludge settled out. The second part of the study assessed the fate and behavior of ZnO ENPs in wastewater treatment systems. This study was carried out in a simulated activated sludge wastewater treatment plant (AS WWTP), constructed in accordance to the Organization for Economic Co-operation and Development (OECD 303 A) guidelines. Results from the ICP-OES analysis for zinc indicated 50 – 200 μgL-1 and about 3 000 mgkg-1 were released into the effluent and sludge, respectively, after spiking the influent wastewater with 5 mgL-1 ZnO ENPs. Moreover, we noted that increasing the ZnO ENPs concentration up to 20 mgL-1 resulted in a linear increase in the zinc releases into effluent wastewater. However, the increase was insignificant in comparison to the zinc found in the control unit. Therefore, the findings indicated that ZnO ENPs had stronger affinity for the suspended bio-solids during wastewater treatment, and postulated that the ENPs removal from the influent wastewater was due to bio-sorption, and bio-solid settling mechanisms. These were confirmed by results from XRD and diffuse reflectance spectroscopy (DRS) analysis of the sludge as they showed the presence of ZnO in the sludge. The dissolved organic carbon (DOC) and chemical oxygen demand (COD) were concurrently monitored during the ENPs exposure studies to indirectly assess the ZnO ENPs impact to the bacterial degradation of the organic matter. An average of 43 and 91 % for DOC and COD removal efficiencies, respectively, were observed throughout the study. Overall, from results obtained indicated the suitability of the OECD 303 A method to assess the fate and behavior of ZnO ENPs in WWTPs. Secondly, in light of low concentrations of ZnO ENPs found in the treated effluent due to their removal with the waste activated sludge (WAS), suggest low likelihood of ZnO ENPs release and dispersion into the aquatic systems from WWTPs as point sources. Finally, the elevated concentrations of ZnO ENPs in the sludge therefore necessitates additional treatment steps to ensure mitigation of possible dispersion of ENPs from various disposal mechanisms such as landfilling, incineration, and agricultural applications.

The effects of in-basin storage of sludge on the iron, manganese, and TOC removal of water treatment plant (WTP) clarifiers and on the dewatering characteristics of sludge were examined. The use of chlorine dioxide as a preoxidant to retard observed detrimental effects was also investigated. Sludge samples that were stored over a period of 120 days were found to release up to ten times the original supernatant concentration of iron and manganese from the sludge into the overlying supernatant liquor when sludge redox potential values decreased below +100 mV. Organic carbon also increased in the supernatant but to a lesser extent. Sludge dewatering characteristics as measured by specific resistance and capillary suction time were found to improve when sludge redox potential readings remained over 100 mV but varied greatly when readings were below this level. Field monitoring and sampling of the clarifiers at Lee Hall WTP and Harwood's Mill WTP from April to July showed that the removal efficiencies of the clarifiers was not related to in-basin sludge storage. This conflicted with a later portion of the study and was thought to be due to the lack of standardized sampling techniques. The final phase of the investigation dealt with the use of chlorine dioxide to retard the negative effects of in-basin storage of sludge. Sludge accumulation in clarifiers resulted in decreased iron and manganese removal efficiencies when chlorine dioxide was not used. Addition of chlorine dioxide improved the iron and manganese removal efficiencies of the clarifiers. Sludge dewatering characteristics were found to improve with the use of chlorine dioxide as a preoxidant. / Master of Science

published_or_final_version / Civil and Structural Engineering / Master / Master of Philosophy

Providing water and proper sanitation to poor communities by 2015 is one of the United Nations targets for this millennium. In South Africa many communities aspire to waterborne sanitation. However, there is a technology gap for decentralized and sustainable waterborne sanitation systems capable of treating domestic wastewater (Foxon et al., 2006). Although domestic wastewater is more commonly treated using aerobic processes, anaerobic processes may be more appropriate for decentralized applications since they do not require aeration. Research is currently being undertaken to understand the behavior of a combined ABR-MBR unit for treating domestic wastewater. In this study, the anaerobic baffled reactor (ABR) was investigated by analyzing physico-chemical and biochemical data from experiments on a laboratory-scale ABR. This anaerobic reactor was treating complex particulate wastewater made up of sludge from the ventilated improved pit latrine toilets (known as VIP sludge). The main focus of this study was to establish the relationship between the increasing organic loading rates and the effluent characteristics (such as chemical oxygen demand: COD and extrapolymeric substances: EPS). The present work was structured in two parts; in the first part the reactor was operated at constant hydraulic retention time (HRT) without controlling feed characteristics. In the second part, the ABR was operated with step increases in organic loading rates. It was logistically not possible to provide a feed of real domestic wastewater to the laboratory-scale equipment. Consequently, a pit latrine sludge diluted with tap water was used to feed the ABR. This feed was found to have different biodegradability characteristics compared to domestic wastewater. However, the results still give insight into the performance of the ABR and into the treatability of VIP sludge. COD removal ranged from 52 to 80 % depending on the inlet COD. Some COD removal was due to solids retention in compartments, while it was estimated that only 28% of COD removal was due to biological degradation. Soluble extrapolymeric substances (proteins and carbohydrates) which are usually a by -product of anaerobic degradation were higher in the feed than in the effluent despite the increasing organic loading rates. However, more than 50 % of soluble extrapolymeric substances from the influent remained in the effluent and were found (in a parallel project) to influence membrane fouling in the membrane section of the experimental set-up (ABR-MBR unit). Parameters such as pH, conductivity, alkalinity, total and volatile solids were also investigated in this study. The pH decreased slightly from the inlet to the outlet during all runs even though the loading rates were increased. Conductivity increased significantly from influent to effluent with the increasing organic loading rates. Large amounts of total solids were retained in the reactor during the treatment process. Low alkalinity production was recorded during the operation of the reactor. In most cases, the data recorded in this study showed a low biological activity taking place while the reactor was working at room temperatures. Overall, up to 80% of removal efficiencies in terms of total COD and solids were recorded with increasing organic loading rates at constant hydraulic retention time. While these results do not allow the prediction of ABR-MBR performance during the treatment of real wastewater, it was concluded that: Most solids retention occurred in the feed tank. Most COD removal occurred as a result of solids retention and digestion. Loading characteristics did not strongly influence effluent EPS, pH or alkalinity, but did influence COD and conductivity. The relatively low biodegradability of the feedstock indicates that anaerobic digestion is not the most appropriate treatment for VIP sludge. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

The purpose of this study was to extend our understanding of the ecological relationships of P. aeruginosa by investigating the differences or similarities between the strains of this organism found in sewage and those found as pathogens in human infections. This research was approached by comparing the serological types of P. aeruginosa isolated from sewage contaminated waters in Argentina (South America) to those isolated from sewage contaminated waters in Texas. They were typed with sera obtained using P. aeruginosa isolated from human infections. The data obtained revealed that bacteria isolated from sewage in Texas and from soil and water in Argentina are antigenically similar to those isolated from human infections.

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