Please read the abstract in the section 00front of this document / Dissertation (M Eng (Control Engineering))--University of Pretoria, 2007. / Chemical Engineering / unrestricted

The objectives of this investigation were to: • Develop a capacitance measuring device that can be used for measuring composition of ethanol-water mixtures. • Implement this measurement technique on a laboratory clistillation column for top product composition measurement and control. • Compare the results obtained in this manner with previously used inferred measurements by temperature. Experiments were conducted to calibrate the capacitance cell ie, to obtain a relation between composition of an ethanol and water mixture and the output of the capacitance cell. Open loop tests were executed on the distillation column to determine if the capacitance device had any negative influence on measurement compared to composition measurements via temperature. Top product composition control using the capacitance cell under dosed loop conditions was also tested, to observe the capacitance cell's performance. The capacitance cell gave repeatable readings during the calibration procedure. In the open loop tests, process models were obtained for control purposes and no negative influence was observed. The capacitance cell's closed loop responses were observed to be satisfactory. It was simple to construct, easy to operate and proved to be a relatively inexpensive device. In the final analysis, the capacitance cell proved to be a useful device in direct measurements of composition of binary mixtures, and offers scope for further development in its application to the control of top product composition in distillation columns of industrial scale. / Dissertation (M Eng (Control Engineering))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

International LCA literature indicates that little data is available pertaining to potable water production and supply, in particular with respect to the environmental burdens generated within the system. This study aims to investigate and assess the environmental burdens associated with the potable water supply to an industrial area (Rosslyn, north of Pretoria, in the Tshwane Metropolitan Municipality). The procedure, as well as the assessment of the environmental impacts of a life cycle, is dependent on a comprehensive life cycle inventory (LCI) of the evaluated system. Water use is included in LCIs, which are incorporated into the LCIA procedure, as it reflects a direct extraction from available resources. The water supply system diagram has been developed and data was collected, treated and analysed in the inventory analysis phase. The study closely followed the four phases as stipulated in the International Organization for Standardization (ISO 14040 series of standards) for conducting LCAs, including: -- goal and scope definition; -- LCI analysis; -- LCIA; and -- interpretation, conclusions and recommendations. The methodology used in the impact assessment phase was the introduced LCIA framework for South Africa in order to determine the extent of different environmental impacts. The inventory analysis, conforming to the scope of the study, provided an overall inventory of energy and other resource requirements, emissions to water and air, dust fallouts and solid or liquid wastes for the system under study. By using this methodology and by tracing all unit processes involved in the potable water supply system, the main contribution to the environmental burdens imposed on the potable water supply system was found to be the extraction of the required water from nature to supply potable water to Rosslyn. The toxicity potential impacts on water resources, mainly due to the electricity required for the water supply system, are of minor importance. This conclusion is valid for the system investigated, and as a result, the recommendations for environmental improvements should focus on water losses that must be addressed foremost. What is required at this stage is strategic planning regarding the extraction, use and conservation of water resources. Furthermore, to optimise all processes of water extraction, and to make them more efficient, electricity and other energy inputs are also of importance, albeit to a lesser extent. / Dissertation (M (Applied Sciences : Environmental Technology))--University of Pretoria, 2007. / Chemical Engineering / unrestricted