3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Municipal solid waste management in South Africa: evaluation of waste to energy technologies for generating electricity from municipal solid waste, Gauteng Province(2019) Dlamini, Smangele Qondile“Waste-to-energy” technologies have been presented as one of the avenues to improve the management of solid waste through the recovery of waste whilst promoting a clean urban environment and increasing renewable energy generation. The Gauteng province, however, is still high and solely dependent on landfills for municipal solid waste management. Because of the concern on the depletion of the City of Johannesburg’s landfills airspace by the year 2023, increasing waste generation and greenhouse gases emission, the province has an urgent need for a better waste management strategy. This projection becomes a motivation for the identification of suitable waste-to-energy alternative avenues to manage waste in the province. This study evaluated the potential of municipal solid waste for electricity production in nine municipalities in the Gauteng province using landfill gas to energy, incineration and anaerobic digestion technologies as well as the economic viability of the waste-to-energy technologies. The LandGEM equation was used to estimate methane generation from the waste generated in each year in order to evaluate the electricity generation potential of the technologies. The levelised cost of energy, net present value and payback period methods were used to determine the economic viability of the technologies. The study also evaluated the global warming potential, acidification potential and dioxin/furan emission potential of the waste-to-energy technologies using the life cycle assessment methodology. Four scenarios were evaluated, namely scenario 1- landfill, scenario 2 - landfill with energy recovery, scenario 3 - incineration with anaerobic digestion and scenario 4 - incineration with landfill with energy recovery. Key findings revealed that the City of Johannesburg municipality has the highest waste generation potential of 2.18925×109 – 3.9103×109 kg/yr between the years 2016 to 2035 with methane generation estimates of 181700000 m3/yr (12210 ft3/min). The incineration technology is the next best and appropriate technology option for municipal solid waste management in the province in terms of waste recovery and electricity generation potential. However, from an economic point of view, anaerobic digestion technology presented itself as an economically viable waste-to-energy technology with the lowest payback period compared to landfill gas to energy technology and incineration technology. Scenario 3 (incineration with anaerobic digestion) has the highest greenhouse gas emissions in all the municipalities. This was expected as the electricity generation potential for incineration was high in all the municipalities followed by the anaerobic digestion technology with high methane generation during biological degradation of organic waste. Scenario 4 (incineration with landfill gas to energy) has the highest acidification potential compared to the other scenarios. Dioxin emission in scenario 4 (incineration with landfill gas to energy) was higher than that in scenario 2 (landfill gas to energy) and it was not surprising as dioxin are emitted through the combustion of waste. This study is very useful to policy makers, scientists and investors for decision making purposes as it could lead to optimal investment in waste-to-energy technologies.Item Evaluation the knowledge and implementation of waste management by contractors in Gauteng province(2019) Maneli, SiyawakhaWhile much has been written about the barriers to sustainable construction globally and particularly in South Africa, the implementation of the concept is still a challenge. The aim of this research is to investigate the awareness and understanding towards environmental aspects specifically on-site Construction Waste management (Handling of waste, use of prefabrication and reuse of waste) as sustainable practise amongst construction contractors in South Africa. These barriers have limited adaptability within the industry and hence depriving the industries of the expected benefits associated with sustainable construction practices. This research focuses on the knowledge, implementation and the impact of construction waste management and the use of prefabrication as sustainable construction practices in South African buildings projects, Gauteng. A questionnaire on construction waste management was directed to experienced professionals, on recently completed building projects and on-going building projects. Previous results shown that construction waste management by reduction, re-use and recycle is one of the major benefits of using prefabrication compared with conventional construction. In this study it was observed that South Africa contractors, particularly in the Gauteng province, fail to adopt basics of sustainable construction practices in construction of buildings projects. Observed also was the eight (8) most common barriers to the construction of sustainable buildings are Knowledge and Implementation, Prefabrication as a substantial componentry, Waste management as a sustainable construction practice reduces cost, Precast as sustainable construction practice at design stages, Materials recycle and re-use on your projects as sustainable construction practice. Others are; the effect of cost of sustainable materials compared to normal construction, environmental management, exposure to experts in one’s profession and the commitment of construction firm/ organisation. Also noticed was that some contractors mentioned government involvement or funding into the practice of sustainable construction practices. In conclusion, the research demonstrates that much needs to be done in Gauteng province with regards to waste management and sustainable construction practise be it by the government through funding and schools including professionals working in the industry.Item Critical factors in effective construction waste minimisation at the design stage: a Gauteng region case study(2015-04-28) Wortmann, Anine EschbergerConstruction waste minimisation and avoidance at the design stage of a construction project is the most favourable solution in the existing waste management hierarchy triangle. However, there are currently only a limited number of exploratory and context-specific studies that state effective construction waste minimisation factors which can be implemented during the design stage. This can be regarded as a relatively new concept and new research topic, especially as no studies have been done in a South African or a Gauteng region context. This research report aims to address this local knowledge gap. The research method included an initial conceptual framework of factors (identified from surveying both global and local literature) as a launch pad in order to quantitatively survey design consultants in Gauteng with regards to both the significance and ease of implementation of the identified factors. The research target population consisted of; architects, architectural technologists, architectural draughtsman, structural engineers, structural technologists, structural draughtsman and finally sustainability consultants. The target population was further narrowed by only including designers who have both attempted to minimise construction on greenfield projects in Gauteng and who have received Green Building Council of South Africa (GBCSA) accreditation on the same project. This report presents a hierarchical list of twenty-six critical factors that can be implemented during the design stage in order to minimise or avoid construction waste in the context of Gauteng, South Africa. The report further indicates which of these factors will be easier to implement than others. These factors are aimed mainly at clients of construction projects, as they are in essence the stakeholders who will contractually enforce designers to implement these construction waste minimisation factors in order to lower project costs. Furthermore; these factors will also serve as valuable references for the Gauteng Provincial Government as the factors can be utilized in order to drive provincial construction waste regulations and eventually national reform.