Growing concerns regarding climate change, the increase in demand for energy and the efficient utilization of energy have become of major interest in applications of heating and power generation. A large portion of the energy input to these applications is lost, due to their typical inefficiencies, in the form of waste thermal energy which, if captured and utilized, can offer an abundant source of energy for electricity generation and heating purposes. The use of thermoelectric generators (TEGs) of different designs in waste heat recovery applications has been pursued over the past few decades as the generation of electrical power using TEGs has become viable compared to other conventional systems at low temperatures. This study focuses on the implementation of an annular design for integrated TEG modules in a heat exchanger device for waste heat recovery and the investigation of the effect of different TEG design parameters on the device performance. The integration of the annular TEG design in the heat exchanger was studied using a developed numerical model to investigate the interaction between the heat transfer and the thermoelectric effects and evaluate the performance under specific operating conditions. The heat transferred from the exhaust to the water flow through the TEGs was modelled using a thermal network for the heat flow, coupled with an electrical circuit for the power output. The model was validated using experimental results of the first generation of the TEG device with good agreement (3-6 %) between the predicted and measured performance results: power output, efficiency and the exhaust and water flow temperatures. With the objectives of maximizing the power output and improving the power characteristics, a half annular TEG design was presented. It was able to generate the same power output with double the voltage and half the current, thus improved the power characteristics required for functional operation, compared to the full annular design. The effect of the annular TEG design dimensions on the device performance was studied for a multi-row heat exchanger using the numerical model. The results showed that a maximum power output can be obtained at optimum TEG diameter ratio and thickness. In addition, the TEGs performance was studied under different electrical connection configurations in series and in parallel. The series connection between TEG rows showed better power output characteristics with lower current output, minimal power loss due to temperature mismatch and higher voltage output. The effect of heat exchanger design considerations such as the axial heat conduction was also investigated using the numerical model and the results were compared with an ANSYS model for verification. Good agreement was demonstrated and the results showed a decrease in the total power output of multiple TEG rows when axial conduction of heat was allowed between the TEGs hot-side surfaces in the heat exchanger. A dimensions map was created for annular TEGs integrated in a heat exchanger combining the effects of varying the TEG diameter ratio and thickness on the power output. Further, a dimensionless design parameter (β) was introduced to locate the maximum power region on the map. Using the map as a design tool, the dimensions of the annular TEG modules in a heat exchanger were determined to maximize the power output under a typical current output constraint in order to improve the system power characteristics. Using the map, it was shown that the current output could be reduced by 46 % of its value at the maximum power available on the map and the resultant power output could be maintained at 98 % of its maximum value. This also resulted in a 48% reduction in the TEG material volume and an increased voltage output of the device. As a result, the power output was maximized, the current output was limited to reduce losses in the power management system components and material volume reduction was achieved which would increase the device power density and reduce its overall cost. / Thesis / Master of Applied Science (MASc)

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Land application of poultry litter has been successfully practiced for centuries to maintain and improve soil fertility, although over application may promote loss of nutrients through runoff or leaching. To decrease the potential for adverse environmental impacts of N and P in groundwater, a new approach developed in this research was to use a composted mixture of poultry litter (PL) and yard waste (YW) as a soil amendment for corn (Zea mays L.) production. Objectives of this research were to evaluate effects of pre-compost C:N substrate ratios for poultry litter-yard waste compost (PYC) on the availability of soil P, to determine the P response of corn plants to inorganic P, PL and PYC application, and to study relationships between P availability and both inorganic P and PYC application. Langmuir isotherms were used in this research to select soils with relatively high P fixation capacities. Phosphorus sorption maximum for soils evaluated were as follows: 304 and 449 micrograms of P per gram for A horizon Coastal Plain soils (Series: Kempsville and Myatt, respectively); 487 micrograms of P per gram for an A horizon Ridge and Valley soil (Series: Frederick); 918 and 603 micrograms of P per gram for A horizon Piedmont soils (Series: Elioak and Vance, respectively); 1099 microgram of P per gram for mine tailings (Series: Emporia located in the Coastal Plain); and 1524 microgram of P per gram for A and upper mixed horizon soil (Series: Starr from Piedmont region). Based on intermediate to high P sorption maxima, soil from the Vance and Starr series and mine tailing from Emporia series were selected for greenhouse research to evaluate P availability of PYC . Treatments applied to the soil in the greenhouse and field studies consisted of various levels of P as Ca(H₂PO₄)₂.H₂O, PL and PYC from 15:1, 20:1, and 25:1 C:N ratio substrates. Each P source increased dry weight of corn plants grown in the greenhouse by alleviation of P deficiency. Phosphorus uptake from PYC and PL application was either equal to or higher than P uptake from an equal level of P application as Ca(H₂PO₄)₂.H₂O. Application of 87.2 kg of P per ha increased corn grain yields in a field experiment on Vance sandy loam from 6340 kg per ha on the control to a range of 10,170 to 11,350 kg ha for PYC digested from the three C:N ratio substrates. The yields on PYC treatments were attributed to a combination of factors including slow mineralization of P with less fixation during the growing season. The low P fixing capacity results from the blockage of H₂PO₄⁻ sorption by competition of negative charge from organic material and from the displacement of H₂PO₄⁻ in soil solution by OH⁻ from application of the alkaline composts. It would be desirable from the standpoint of more PL utilization to prepare composts from low substrate ratio substrates. Hence, in this research composts were prepared from 15:1, 20:1, and 25:1 C:N substrates, which consisted of PL and YW. The composting process was complete after only four months for the PYC from the 20:1 and 25:1 C:N ratio substrates. Yard waste compost without PL may require somewhere between two to three years for complete composting as opposed to four months with PL addition. The composting was incomplete in four months (presence of undigested leaves and NH₃) for the PYC from the 15:1 C:N ratio substrate. The latter compost resembled poultry manure rather than a high quality compost after the 4-month composting period. / Ph. D.

Conventional landfills are built to dispose of the increasing amount of municipal solid waste (MSW) generated each year. A relatively new type of landfill, called a bioreactor landfill, is designed to optimize the biodegradation of the contained waste to stabilized products. Landfills with stabilized waste pose little threat to the environment from ozone depleting gases and groundwater contamination. Limited research has been done to determine the importance of biodegradation enhancement techniques and the analytical methods that are used to characterize waste stability. The purpose of this research was to determine the effectiveness of several biodegradation enhancements and to evaluate the analytical methods which predict landfill stability. In the first part of this study leachate recirculation, and moisture and temperature management were found to significantly affect the biodegradation of MSW. Leachate recirculation, increased moisture, and higher temperatures increased the first order degradation rates of cellulose and volatile solids. Of the three enhancements, temperature was shown to have the biggest impact on the biodegradation of waste, but sufficient moisture is critical for degradation. Plastic material was also shown to significantly impact the measurements for volatile solids and lignin, which is important if these measurements are used to establish waste stability. In the second part of the study the analytical methods used to characterize waste were evaluated to determine if relationships existed between the methods and which methods were the best predictors of waste stability. Volatile solids and cellulose were found to be the best parameters to monitor waste in landfills. These parameters correlate well with each other, age of the waste, and other parameters. Volatile solids and cellulose are also relatively easy to determine, quick, and show little variation. / Master of Science

A test method and the associated equipment have been developed to investigate the effect of suspended solids on the flow of fluid into a deep injection well system. Preliminary testing indicates that the equipment and test method can be used to determine the permeability of rock samples with a high degree of accuracy. Additionally this equipment can be used in a testing program which will eventually lead to the development of guidelines for the degree of pre-injection treatment required for suspended solids so that the operational life of the well is not impaired.

Yes / This paper is a comparative analysis of Municipal Solid Waste Management in West Africa focusing on Ghana, Mali and Nigeria. The paper offers a rich discussion on Municipal Solid Waste, (hereinafter referred to as MSW), its negative impacts, possible benefits and missed opportunities due to mismanagement of the same. The discussion focuses on both international and domestic legislation of the case study states on MSW and the right to environment. Inevitably, this extends to policy considerations in as far as they impact on MSW management, and to recommendations intended to enable the case study states realise the benefits of a proper MSW management system that is in line with global standards and the right to clean and healthy environment.

Submitted in fulfilment of the requirements of the egree of Master of Technology: Chemical Engineering, Durban University of Technology, 2011. / The South African electroplating industry generates large volumes of hazardous waste water that has to be treated prior to disposal. The main source of this waste water has been the rinse system. Conventional end-ofpipe waste water treatment technologies do not meet municipality standards. The use of technologies such as membranes, reverse osmosis and ion exchange are impractical, mainly due to their cost and technical requirements. This study identified source point reduction technologies, close circuiting of the electroplating process, specific to the rinse system as a key development. Specifically the application of a low flow counter current rinse system for the recovery of the rinse water in the plating bath was selected. However, the recovery of the rinse tank water was impeded by the low rates of evaporation from the plating bath, which was especially prevalent in the low temperature operating plating baths. This master’s study proposes the use of an induced draft evaporative cooling tower for facilitation of evaporation in the plating bath. For total recovery of the rinse tank water, the rate of evaporation from the plating bath has to be equivalent to the rinse tanks make up water requirements. A closed circuit plating system mathematical model was developed for the determination of the mass evaporated from the plating bath and the cooling tower for a specified time and the equilibrium temperature of the plating bath and the cooling tower. The key criteria in the development of the closed circuit plating system model was the requirement of minimum solution specific data as this information is not readily available. The closed circuit plating system model was categorised into the unsteady state and steady state temperature regions and was developed for the condition of water evaporation only. The closed circuit plating system model was programmed into Matlab and verified. The key factors affecting the performance of the closed circuit plating system were identified as the plating solution composition and operational temperature, ambient air temperature, air flow rate and cooling tower iv packing surface area. Each of these factors was individually and simultaneously varied to determine their sensitivity on the rate of water evaporation and the equilibrium temperature of the plating bath and cooling tower. The results indicated that the upper limit plating solution operational temperature, high air flow rates, low ambient air temperature and large packing surface area provided the greatest water evaporation rates and the largest temperature drop across the height of the cooling tower in the unsteady state temperature region. The final equilibrium temperature of the plating bath and the cooling tower is dependent on the ambient air temperature. The only exception is that at low ambient air temperatures the rate of water evaporation from the steady state temperature region is lower than that at higher ambient air temperatures. Thus the model will enable the electroplater to identify the optimum operating conditions for close circuiting of the electroplating process. It is recommended that the model be validated against practical data either by the construction of a laboratory scale induced draft evaporative cooling tower or by the application of the induced draft evaporative cooling tower in an electroplating facility.

Construction waste generation is a global issue in the sustainable construction context and several studies have been performed in different parts of the world to develop methods and tools for waste prevention, reduction, reuse and recycling. Most of these studies adopted a linear approach by focussing on a specific project phase, such as design, procurement or construction. However, there is a consensus in the literature that factors causing construction waste span across the project life cycle and recent researchers emphasised the need for a more integrated lifecycle approach to holistically assess and evaluate causes of waste to suggest recommendations to reduce lifecycle construction waste generation. Over recent years, the UK government has been investing billions of pounds in new and refurbished healthcare projects, where the healthcare buildings are often referred to, in literature, as complex buildings. This large investment has created a number of sustainability issues including water consumption, CO2 emissions, energy consumption, and more significantly construction waste generation. However, no significant research has been undertaken to propose a systematic construction waste minimisation mechanism for healthcare construction projects. Therefore, this research aims to develop a lifecycle construction waste minimisation framework for healthcare projects (HC-WMF). In order to identify the research problem and construction waste generation issues peculiar to healthcare projects, nine preliminary interviews were conducted with healthcare clients (N=3), architects (N=3), and contractors (N=3). The findings revealed that healthcare projects generate high rates of waste compared to other building projects throughout the project lifecycle, identified complex features that have an effect on waste generation, and identified particular causes of construction waste in healthcare projects. A further in-depth study based on four case studies was undertaken to understand the impact of waste generation due to the causes of waste, the relationship between complex features in healthcare projects and the causes of waste, and best waste minimisation practices to be implemented throughout a healthcare project lifecycle to address construction waste causes. Three interviews (client, architect, and contractor) from each case study were undertaken during the data collection stage. A Healthcare Construction Waste Minimisation Framework (HC-WMF) and Self-Assessment Tool (SAT) were then developed based on the findings of the literature review, preliminary data collection study and case studies, and adoption of the key concepts of problem solving methodology. This HC-WMF comprised six waste minimisation strategies (project documents management, stakeholders waste awareness, communication and coordination, buildability, materials selection and procurement, and change management) to be followed throughout the lifecycle stages of a healthcare project. SAT provides a means to assess the effectiveness in implementing HC-WMF and to obtain feedback and learning outcomes for continuous further improvements. In order to validate the developed HC-WMF and SAT a validation questionnaire (N=26) and validation interviews (N=4) were conducted. The validation results showed that the HC-WMF and SAT would be very useful in reducing construction waste generation from healthcare projects. The research contributes to construction waste minimisation research introducing a novel approach to lifecycle waste reduction. Also, the research revealed the complex features in healthcare projects that affect construction waste generation, causes and origins of waste peculiar to healthcare projects, and best waste minimisation strategies to implement to reduce construction waste generation from healthcare projects. Most importantly, through HC-WMF, this research produced a set of guidelines to be followed throughout the healthcare project lifecycle to reduce construction waste generation. The study has made recommendations which, if adopted, will lead to significant improvements in sustainable healthcare construction due to construction waste minimisation. The content should be of interest to clients, designers, and contractors dealing with construction waste minimisation and sustainable construction in healthcare projects. Key words: Construction waste, Healthcare, Causes of waste, Healthcare complexities, Waste minimisation, UK.