M.S.

A stochastic dynamic constituent transport model was developed, capable of simulating the operation of a water distribution system containing pumps and storage tanks, and subject to random demands and contaminant inputs. Long term operation of a hypothetical small town water supply system containing one pump station and one storage tank was simulated while the system was subjected to external contaminant inputs. Repeated simulations were made under different regimes of external contamination applied to the tank, the pump station and at system nodes, and internal contamination representing biofilm effects based on assumed relationships between flow velocities and bioflim cell detachment. Seven sampling plans representing regulatory requirements and industry practice were applied during the simulation to evaluate their ability to detect the contamination under a presence/absence criterion. The simulations were able to identify contamination patterns and provide information useful in the definition of sampling plans. Time of sampling was found to be as important as location. This was true both within the monitoring period, and particularly within the diurnal cycle of demand. Spreading samples over different days within the monitoring period rather than sampling all on one day, always improved contaminant detection. Detection by plans based on fixed times and locations were very sensitive to those times and locations. There was no best plan suitable for all situations tested. The better sampling plans were those that captured the temporal and spatial contamination patterns present in the system. No consistent advantage was noted from sampling in proportion to population served or in locating sampling nodes systematically instead of randomly. The location and timing of sampling for most plans could be improved with the knowledge of actual contamination patterns and timing provided by the model. The presence of a storage tank was found to have a strong influence on hydraulic patterns and the location and timing of contamination reaching different parts of the system. / Ph. D.

A bench study was conducted to compare two membrane filter techniques for their efficiency in recovering fecal coliforms exposed to selected heavy metals. The effects on recovery by increasing time and metal concentration were also examined. The recovery methods employed included the standard membrane filter technique (S-MF) and a modified membrane filter technique (M-MF)~ which consisted of a lactose agar overlay and a five-hour preincubation at 35 C. The heavy metals Cd, Cr, Pb, and Zn were examined, each at two concentrations, to evaluate their effect on the recovery of the I. coli test organism, after exposure for 6, 24, and 48 hours. A statistical analysis of the data found the recoveries obtained by the M-MF to be significantly greater (.0001 level) than those of the S-MF, in all cases. Time was also found to significantly effect recovery, with recoveries decreasing as time increased. A significant difference was also found between the effects of the heavy metals tested and the concentrations of metals was likewise found to significantly effect recovery, with decreased recoveries being obtained at the high concentration of each metal. / Master of Science

Abstract available in file 07summary.pdf / Thesis (PhD (Microbiology))--University of Pretoria, 2007. / Microbiology and Plant Pathology / unrestricted

Contaminants can exist in a wide range of states in aqueous environments, especially in surface waters. They can be freely dissolved or associated with dissolved or particulate organic matter depending on their chemical and physical characteristics. The freely dissolved fraction represents the most bioavailable fraction to an organism. These freely dissolved contaminants can cross biomembranes, potentially exerting toxic effects. Passive sampling devices (PSDs) have been developed to aid in sampling many of these contaminants by having the ability to distinguish between the freely dissolved and bound fraction of a contaminant. A new PSD, the Lipid-Free Tube (LFT) sampler was developed in response to some of the shortcomings of other current PSD that sample hydrophobic organic contaminants (HOCs). The device and laboratory methods were original modeled after a widely utilized PSD, the semipermeable membrane device (SPMD), and then improved upon. The effectiveness, efficiency, and sensitivity of not only the PSD itself, but also the laboratory methods were investigated. One requirement during LFT development was to ensure LFTs could be coupled with biological analyses without deleterious results. In an embryonic zebrafish developmental toxicity assay, embryos exposed to un-fortified LFT extracts did not show significant adverse biological response as compared to controls. Also, LFT technology lends itself to easy application in monitoring pesticides at remote sampling sites. LFTs were utilized during a series of training exchanges between Oregon State University and the Centre de Recherches en Ecotoxicologie pour le Sahel (CERES)/LOCUSTOX laboratory in Dakar, Senegal that sought to build "in country" analytical capacity. Application of LFTs as biological surrogates for predicting potential human health risk endpoints, such as those in a public health assessment was also investigated. LFT mass and accumulated contaminant masses were used directly, representing the amount of contaminants an organism would be exposed to through partitioning assuming steady state without metabolism. These exposure concentrations allow for calculating potential health risks in a human health risk model. LFT prove to be a robust tool not only for assessing bioavailable water concentrations of HOCs, but also potentially providing many insights into the toxicological significance of aquatic contaminants and mixtures. / Graduation date: 2010

Previously, issues concerning the use and conservation of the natural resources were restricted to certain groups of individuals, normally those considered to be scientific experts. However with the emergence of sustainable development and the adoption of its principles therein, there has been increased community concern over environmental quality issues resulting in pressure for transparency in environmental decision-making processes. The result has been a dramatic expansion in the number of organisations at the local, national and global scales committed to environmental improvement. This in turn has let to dramatic changes in the role of the public in decisions relating to natural resource management. Participatory development is now acknowledged as critical in achieving sound environmental management. The initiation of community-based environmental decision-making has led to the formation of new and interesting partnerships. Environmentalists, communities, policy makers and business people have begun to work together in an attempt to find consensus concernIng environmental problems and related socio-economic inequalities. This has resulted in the development of new ways of integrating local and scientific knowledge systems. This thesis illustrates community-based environmental decision-making in the management of the use of the south coast of Durban. It outlines a partnership, through the formation of the Permit Advisory Panel (PAP), comprising industry (Sappi Saiccor), government, through its Department of Water Affairs and Forestry, environmental organisations, and the local people in the monitoring of the impacts of effluent produced by the industry and disposed of into the sea. The aim of this thesis is to develop an alternative methodology that will be acceptable to all stakeholders, for the collection and analysis of data in the monitoring of the Sappi Saiccor effluent. This was achieved through the following objectives: to develop a methodology for the collection and analysis of data, to assess the performance of the new pipeline in terms of reduced aesthetic impacts of the effluent, to assess the role of local knowledge in the monitoring process, and finally to assess the role of this study in the functioning of the PAP. This thesis attempts to integrate qualitative and quantitative methodologies. The subjective local data collected by the divers is analysed using statistical methods to assess the impacts of the effluent on marine water quality and the effect the new pipeline has had in reducing these impacts. Qualitative surveys such as questionnaires and interviews were administered to assess the role of local knowledge in the monitoring process and also to assess the role this study has had in the functioning of the PAP. The statistical analysis did not reveal any major improvement in underwater visibility since the pipeline was extended. There is a 6% and 4% improvement in the number of effluent days and visibility respectively. This however is due to some limitations inherent in the data collection process, and as a result the improvement brought about by the pipeline extension has been toned down. An effluent and visibility index is therefore recommended as an alternative method of data collection and analysis to reduce the level of inaccuracy. The role of local knowledge is perceived by many of the PAP members as vital in the monitoring process. This study was therefore thought of as an important step in validating this local knowledge such that it can be a reliable data source to be used in the monitoring process. It also played an important role in resolving the conflict between the PAP members. It is therefore recommended that the divers data should be continually used in the monitoring process, though the divers have to be more actively involved. The PAP is therefore tasked with liasing with the community members, especially the divers such that they can assume a more active and responsible role within the PAP. They should be involved in the development of the methods of data collection and analysis. / Thesis (M.A.)-University of Natal, Durban, 2002.