Thesis (Ph. D.)--Duke University, 2008.

Dissolved air flotation (DAF) is an attractive solid/liquid separation process for highly colored, low turbidity water supplies. Low density floc is produced when these waters are coagulated, therefore DAF may be more effective than conventional gravity settling (CGS). Communities required to filter their supplies should consider DAF as an alternative pretreatment prior to filtration. Although DAF is a promising alternative to CGS, no rational basis has been developed for selection, design and operation of DAF facilities. The research objectives were: (1) to develop a fundamental basis for the application of DAF to water treatment, (2) to determine via experiment the key variables which affect DAF performance for the removal of clay turbidity and natural organic matter (NOM), and (3) to compare DAF to CGS. A conceptual model was developed based on colloidal stability and particle deposition and used to identify the variables which affect DAF. The variables which included pH, coagulant type and dose, temperature, DOC and clay concentrations, flocculation time, DAF detention time, and bubble concentration were studied using synthetic waters. Synthetic waters were used to compare DAF to CGS. Synthetic waters were prepared from extracted aquatic fulvic acid and research grade montmorillonite clay--their use allowed water quality variables to be carefully controlled. Synthetic water results were then verified using two natural waters. Modelling predicted that particle stability and size, bubble size and rise rate, bubble volume concentration, and detention time would affect DAF performance. Experiments indicated particles must be coagulated for successful flotation. Temperature and flocculation time affected DAF performance in experiments using alum. It is hypothesized that the effects of cold temperature on DAF performance are due to changes in coagulation mechanism and the physical and chemical stability of the particles as it relates to charge and bound water at the surface. In addition, bubble volume affected DAF performance for high DOC waters and waters containing clay. Comparisons of DAF to CGS indicated that the DOC, organic halide precursors, and dissolved aluminum after treatment were comparable for both. However, DAF produced significantly lower turbidities than CGS, particularly at colder temperatures.

Thesis (M.P.A.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 123-127).

Thesis (M.P.A.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 123-127). Also available in print.

Numerous informal houses have been built on and adjacent to a landfill in iBayi, Port Elizabeth, South Africa, which accepted domestic and industrial waste. Formal housing surrounds most of the site at a greater distance - some 60 m, or further, from the landfill. Both formal and informally housed residents complain of odours, burning eyes, sore throats and headaches - symptoms which they believed were caused by the landfill. The landfill gas and ambient air were analyzed to classify and quantify the VOCs (volatile organic compounds) emitted and then to compare the quantitative data with recognised standards to establish if the residents are at risk. Eighteen target (potentially hazardous) VOCs were quantified. A wide variety of compounds were detected in both the ambient air and landfill gas. The results of the VOC analyses were similar to those of other workers in both the qualitative and quantitative studies. The concentrations of the VOCs were mostly lower than the TLV (threshold limit values) values, but exceeded the MRLs (minimum recommended levels). The combined concentrations of the VOC’s in the ambient air either approached or exceeded the limit values for combined exposure thus indicating that a potential health hazard exists. One third of the VOCs were detected in both the ambient air and the subsurface gas, however, external pollution sources also appear to contribute to the VOC concentrations ambient air. Dangerously high methane concentrations were repeatedly detected in the landfill gas amongst the informal houses. There was a vast improvement in the aesthetic qualities of the landfill since the disposal restriction to accept only domestic refuse and building rubble in July 1997. The ambient air was less odorous and landfill site littered. Fewer informal recyclers were present and their concomitant squabbling over valuables had almost vanished. The management of the iBayi landfill holds much room for improvement. There is potential for serious injury or even death if no action is taken to remedy the problems at the iBayi landfill. A holistic solution will have to be found to make the landfill a safe neighbour. Some complementary analyses (such as pH, heavy metal concentrations in the water and sediments etc.) were performed on the leachate and water surrounding the landfill.

O objetivo deste estudo foi verificar se a evolução do saneamento ambiental promoveu a redução na prevalência de Ascaris lumbricoides na população do município de Pindamonhangaba-SP, como também levantar a distribuição temporal e espacial da freqüência desse parasito e identificar área de risco para sua ocorrência. Para a realização do estudo foi empregado o banco de dados do Laboratório Público do Município, referente ao período de janeiro de 2004 a dezembro de 2007, considerando-se as seguintes variáveis: gênero, faixa etária, local de moradia e o resultado do exame parasitológico de cada indivíduo. Dados do saneamento ambiental foram obtidos junto à Prefeitura e à Sabesp, referentes ao período de 1990 a 2008 e in loco. Baseando-se na organização por setores do município, procedeu-se uma análise comparativa da relação entre resultados parasitológicos e da evolução do saneamento ambiental. Dos 52780 resultados de exames parasitológicos analisados, 18,06% apresentaram alguma espécie de helminto ou protozoário, sendo a freqüência de Ascaris lumbricoides de 0,93%, (média mínima de 0,14% e máxima de 1,85%). Verificou-se uma relação inversa entre a frequência do parasito e de faixa etária e, quanto ao gênero a maior freqüência ocorreu entre os homens. Concluiu-se que no município de Pindamonhangaba-SP, em alguns setores estudados, houve a diminuição da frequência de Ascaris lumbricoides, que coincidiu com o período de implantação do sistema de saneamento ambiental. Há setores, localizados na zona rural, e alguns de zona urbana, que foram identificados como sendo áreas de risco para a ocorrência de A. lumbricoides, devido à condição precária de saneamento e ambiente propício ao desenvolvimento de formas infectantes do parasito. / This study aim was to verify if the sanitation environmental evolution promoted the reduction of the prevalence Ascaris lumbricoides in the population of Pindamonhangaba town, also to raise the temporary and special distribution of the frequency parasite and identify areas of risks to the occurrence of the worn. Realizing these studies was applied the information from public municipal laboratory for the period of January 2004 up to December 2007, considering the following changeable, such as: gender, age, the place of living and the result of the parasitosis exam of each person. Data of environmental sanitation were from the obtained municipality and of Sabesp, for the period 1990 to 2008 and on the spot. Based on the organization by sectors of the municipality, was made a comparative analysis of the relationship between parasitological results and the developments of environmental sanitation. Among 52780 result of the parasitosis exam analyzed, 18,06% presented some parasitosis spicie, being the frequency of Ascaris lumbricoides 0,93% (minimum average of 0,14% and 1,85% maximum). There was an inverse relationship between the frequency of the parasite and age, regarding gender the prevalence was higher among men. Concluded that in Pindamonhangaba town- São Paulo some areas studied there was the diminish of the frequency of Ascaris lumbricoides, that coincided with the period of the establishment of the sanitation environmental. There are some areas located in the countryside and some in the town being areas of risks to the occurrence of A. lumbricoides, because of bad condition of sanitation and suitable environment to the development of the forms infecting.

The provision of a basic water supply and sanitation service to the 12 million South Africans without an adequate water supply and the 21 million without basic sanitation is a mammoth task that is currently being undertaken by the Department of Water Affairs and Forestry. Billions of rands have been spent on, and committed to, water and sanitation projects that involve national, provincial and local spheres of government, as well as parastatals, non-government organisations and private developers. It is acknowledged that important successes have been achieved in the water and sanitation sector. However, despite the provisions provided in national and local legislation, internationally lauded policy directives, the numerous studies undertaken and recommendations made by institutions such as the Water Research Commission, problems have continued to emerge in the sustainable delivery of water and sanitation projects, particularly in the peri-urban and rural areas. It is clear that the installation of physical structures such as pipes, taps and ventilated improved pit latrines in these areas have created a sense of 'delivery' however, little thought seems to have gone into how these projects are to be sustained. International experience has shown that the concept of 'community ownership' is very important in providing sustainable water and sanitation services. The most important principles in achieving sustainability are community participation and community decision-making throughout both the development of the project as well as the further operation and maintenance of the system. International experience has also shown that financial contributions towards the scheme from the community (in cash, labour or materials), also assists in obtaining community ownership. Over the past decade emphasis in South Africa has shifted towards community participation and the empowerment of previously disadvantaged communities where communities play an active role in determining the level of service provided and the manner in which these services are delivered. However, current government policy advocates that water must be treated as an economic resource to achieve sustainability and this does not always lie comfortably with the policy of delivering free basic water. As a result of these two often-juxtaposed concepts, the delivery of sustainable water and sanitation services, a function performed by local government, is thus made more difficult. This study assesses the importance of delivering a potable water supply and adequate sanitation service to enhance the quality of lives of people. It also considers the key issues that contribute towards sustainable water and sanitation service delivery, with particular reference to the concept of 'community ownership'. The complex nature of the policy, legislative and institutional framework for water supply and sanitation is considered along with an analysis of the Msunduzi Municipality's water supply and sanitation policy and objectives. The study then focuses on the delivery of water and sanitation services to one such project, Edendale Unit RR (commonly known as Newtown), as an in-situ upgrade case study. A Provincial Housing Board funded project has, over the last five years, provided housing units, roads, stormwater drains, and water and sanitation infrastructure to this community. This initial research is undertaken with the intention of providing an evaluation of the installation of the water supply and sanitation service to the in-situ upgrade of Newtown. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.