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Seasonal changes of metals in the salt marsh and seagrass beds of the Swartkops Estuary

  • Authors: Nel, Marelé Annette
  • Date: 2022-04
  • Subjects: Salt marshes--Effect of heavy metals on--South Africa--Swartkops River Estuary , Estuarine ecology --South Africa --Swartkops River Estuary
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/55734 , vital:53411
  • Description: Estuaries are historically convenient places to build industries, as it was deemed a suitable place to dispose of large quantities of urban and industrial waste into the ocean. At the time it was judged to be appropriate, as rivers can transport and deposit waste into the ocean, which was considered so vast that it is insurmountable. Therefore, metal pollution in estuaries is a well-known occurrence. Coastal wetlands play an important role in the cycling of metals, and act as effective metal sinks. They provide an important ecosystem service acting as accumulators and phytostabilisers, which make toxic levels of the metals unavailable to the rest of the food chain. The overall aim of this study was to assess the metal pollution in the salt marsh (Salicornia tegetaria and Spartina maritima) and seagrass (Zostera capensis) of the heavily developed Swartkops Estuary. Assessing the metals in the estuary will provide information on effective environmental management strategies. Metal concentrations were measured in the rhizosediment of the three wetland plants, bare sediment, and in the tissues (leaves, shoots, and roots) of the selected plant species. Sampling occurred during one seasonal cycle (2019-2020), and in 5 sites along the middle and lower reaches of the estuary. Metal concentrations were not the highest closest to the point sources in the middle reaches, but the metals rather accumulated downstream in Site 3 (Tiger Bay launch site close to the WwTW) and Site 4 (Tippers’ Creek), which were depositional sites. Although these two sites generally displayed the highest metal concentrations, they also had the most seasonal fluctuations in their metal concentrations and sediment characteristics. Flushing events in spring/summer were likely the determining factor of these fluctuations. The mouth of the estuary (Site 5) consistently had much lower metal concentrations, with distinctly more sandy, low organic content sediment, due to marine-influenced flushing. Thus, spatial differences were distinct in the estuary, however seasonal differences did not play an important role in the metal concentrations, indicating that seasonal sampling was not as important as sampling in different sites. Assessing the metal concentrations in different rhizosediment gave important insights on intertidal accumulation and contrasted with the unvegetated (bare) sediment. The metals generally accumulated more, higher up the intertidal range, due to less frequent tidal inundation and flushing — so that metal accumulated in the vegetation in the following order: Z. capensis > S. maritima > S. tegetaria. Moreover, unvegetated (bare sediment) showed much lower metal concentrations compared to the rhizosediment, indicating that the vegetation trapped small particles, and changes the physical environment to concentrate metals in their rhizosphere. Lastly, the plant species all displayed good accumulation of metals in their roots, while Z. capensis also showed remarkable uptake to its leaves. The study identified S. maritima and S. tegetaria as good phytostabilisers, particularly the latter with its vi high metal stocks and slow root turnover rate. The compartmentalization in these plants were unique to each species, corroborating previous assessments that compartmentalization cannot be compared between similar life forms and genera. These results contribute to local and international research on biogeochemistry in wetlands, and assessment of pollution in developed estuaries. Of note is Z. capensis, an endemic Southern African species, which has not been analysed for compartmentalization of metals before. All three of the studied species have potential as metal accumulators, and therefore a sink of metals. They localize the metals, limiting bioaccumulation to the rest of the food chain, which reduces the ecotoxic effect of metals in the environment. Higher accumulation in vegetated (rhizosediment) over bare sediment, make these habitats valuable metal sinks. This increases their importance in estuaries receiving high pollution loads, and they should be prioritized in conservation efforts. Two sites within the Swartkops Estuary, Tippers’ Creek (Site 4) and the Launch Site (Site 3), are potential sites for long-term monitoring due their capacity to trap and accumulate metals. The results of this study will inform local management on the state of metals in the Swartkops Estuary, providing crucial information on the importance of preserving local wetlands for the purpose of regulating toxic levels of metals in the ecosystem. , Thesis (MSc) -- Faculty of Science, Botany, 2022
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  • Date Issued: 2022-04

Smart catchment management and application in the Swartkops River and Estuary

  • Authors: Mmachaka,Thandi Nthabiseng
  • Date: 2022-04
  • Subjects: Estuarine ecology--South Africa--Swartkops River Estuary
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/55932 , vital:54401
  • Description: The influence of urbanization and industrialization on natural resources results in complex water resource management. In South Africa, there has been escalating rural-urban migration, a growing population in urban areas, and the mushrooming of informal settlements in cities over the last five decades. In the pursuit of protecting water resources, these contextual realities create a significant challenge to policymakers, planners, and implementers. Due to rapid population growth, climate change, recent droughts, and growing competition among agricultural, industrial, commercial, environmental, and domestic sectors, water resources are presently under severe stress in South Africa. This situation necessitates the effective management of water resources. This study completed a situational assessment for the Swartkops Catchment to examine the extent of pollution, mapped sources of pollution, investigated water quality governance and identified hot spot areas to provide the foundation for effective and efficient catchment management. To determine the current water quality status of the Swartkops Catchment, this current study investigated spatial and temporal variation in physico-chemical parameters, nutrients, and faecal bacteria. This study applied a mixed-method research design using semi-structured interviews and focus groups discussions as data collection methods to investigate the water quality governance of the Swartkops Catchment. Following the situational assessment of the Swartkops Catchment, the effectiveness of applying innovative smart catchment practices to improve water quality was investigated. The word smart in this context refers to innovative mechanisms that will ensure effective and efficient water resources management. The PHP scripting language (Hypertext Preprocessor), Android studio, Wampserver, and JavaScript were used to develop the Water Use Screening System (WUSS) and Pollution Incident Reporting System (PRS). In South Africa, stormwater infrastructure suffers from unsustainable utilization. Stormwater systems discharge into many of the country‘s rivers and estuaries, including Swartkops, leading to water quality degradation. To improve the Recommended Ecological Category (REC) of the Swartkops Estuary to Category C, drivers that contribute to poor water quality must be understood to inform appropriate management interventions. Results from sampling in Markman Canal were compared with historical water quality data. The present study showed that the Markman Canal contributed faecal bacteria, nutrients, and trace metals to the Swartkops Estuary. The Markman Canal was the greatest source of trace metals to the Swartkops Estuary compared to the other point sources entering the estuary. The results show that arsenic and mercury levels in the Markman Canal and the Swartkops Estuary were higher than that previously measured. Iron and copper concentrations were higher in the Markman Canal whereas only copper increased in the Swartkops Estuary. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
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  • Date Issued: 2022-04

Spatial modelling of accessibility to tuberculosis treatment: the case of Ngaka Modiri Molema District

  • Authors: Ramotsongwa, Karabo Naome
  • Date: 2022-04
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/55435 , vital:52000
  • Description: Accessibility to healthcare refers to the availability, or the provision of healthcare-byhealthcare professionals and stakeholders and individuals' ability to obtain care and treatment. It affects overall physical, social, and mental health; disease and disability prevention; detection and treatment of health conditions; standard of living; preventable death; and life expectancy, and it is crucial to the performance of health care systems around the world. If healthcare services are available and are in sufficient supply, people will be able to seek health care, and a population will have access to services. The leading cause of death globally is Tuberculosis (TB) and South Africa is amongst the top 5 countries most affected by TB. This is aggravated by high HIV/AIDS statistics. Children belowthe age of 4, between the ages of 4- 15, and women and men of working ages are highly affected by TB and it is the primary cause of death in these groups in the Ngaka Modiri Molema District. This study used study tools like Spatial Modelling, Geographic Information Systems and software like ArcGIS 10.5, TerrSet IDRISI 18.30, and secondary data from the North West Departmentof Health (Tier.net &DHIS) and also TB patients’ home addresses to investigate the accessibility of TB treatment in Ngaka Modiri Molema, in order to spatially visualize the distribution of a communicable disease like TB and public healthcare facilities in the Ngaka Modiri Molema (NMM) District and suggest optimum sites for hospital facilities. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
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  • Date Issued: 2022-04

Synthesis and applications of novel fluorescent and colorimetric coumarin-based sensors towards analyte sensing in aqueous systems

  • Authors: Battison, Aidan Leigh
  • Date: 2022-04
  • Subjects: Water-supply engineering--Technological innovations , Polymers--Optical properties , Fluorescent polymers
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/55954 , vital:54558
  • Description: The continuous growth of mankind has not been considerate to the environment. The release of millions of tonnes of toxic heavy metal cations and anionic species through industrial, mining, agricultural, and electronic dumping has led to disease and, in many instances, death. This is usually suffered by low-income informal populations residing in third world countries. Moreover, many unnecessary deaths of children are becoming more prevalent because of consumption and contact with contaminated water, agricultural, and animal sources. Bioaccumulation of these toxic species in fish, plants, and animals, inevitably make their way back to the unaware general population. As growth by mining, agriculture, and electronics are indeed vital aspects of human development, the negative side effects of these activities usually continue unregulated. Therefore, as these processes are set to continue until more stringent regulatory processes are put into legislature; low-cost, sensitive, selective organic based sensors are a step in the right direction towards highlighting the need for environmental restoration and remediation; whilst also aiming to preventing unnecessary disease and death in the process. Herein, coumarin derived small-molecule fluorescent and colorimetric sensors for the quantitative and qualitative assessment of cationic and anionic species in aqueous and organic media are described. Ten fluorescent sensors supporting 1,4-disubstituted triazolyl moieties were synthesized according to Cu(I)-catalyzed azide-alkyne cycloaddition “click” reactions. These sensors were screened for their cationic and anionic affinities in a variety of solvent systems. Majority of the sensors responded well towards Fe3+, characterized by a strong fluorescent quenching response with a good degree of sensitivity and selectivity. Selected sensors were further investigated for their affinities towards anionic species; however, they did not display the same degree of selectivity or sensitivity towards these chosen anions. Titration studies of selected sensors with Fe3+ were able to be used towards determining the modes of fluorescent quenching; the photophysical mechanisms by which quenching occurs; stoichiometric binding ratios, association constants, and the number of coordination sites present between the sensors and Fe3+. Reversibility studies of the sensor-metal complex was investigated with EDTA. Partial reversibility was achieved for the chosen sensors with Fe3+. Hydrogen potential studies further described the application of these sensors over a good pH range. The binding site between the sensors and Fe3+ was investigated by NMR studies. , Thesis (PhD) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
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  • Date Issued: 2022-04

Synthesis of cannibigerol, an antibiotic for methycillin resistant staphylococcus aureus, in continuous flow system

  • Authors: Koeberg, Bryce
  • Date: 2022-04
  • Subjects: Drug resistance in microorganisms , Cannabis -- Therapeutic use -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/55866 , vital:54395
  • Description: This study focuses on the development of a synthetic version of the cannabinoid cannabigerol (CBG) through continuous flow systems. The compound has exhibited antibiotic properties that have been proven to be a potent killer of gram-positive methicillin-resistant Staphylococcus aureus that drive repeat infections. The cannabinoid kills the superbug by disrupting the cell wall integrity of cells that are drug resistant. Research suggests that CBG is not effective against gram-negative multi-drug resistant bacteria. However, when CBG is administered with polymyxin B, an antibiotic that disrupts the outer membrane of gram-negative bacteria the cannabinoid compound wipes out the drug-resistant gram-negative bacteria, thus revealing the extensive medicinal potential of cannabigerol. Cannabinoids, such as CBG, are present in low yields in the plant, depending on the extraction method, usually less than 5% in most strains. Natural medicines have a low amount of active ingredients due to the lab intensive and time-consuming extraction and isolation process; this has hindered the application of natural products in drug development. A major health concern of the human consumption of cannabis plant extracted cannabinoids is that the plant may be contaminated with microbes, heavy metals and pesticides due to the lack of regulation. Thus, it is proposed that these cannabinoids are synthetically produced through the integration of microfluidic technology, eliminating the presence of pesticides, microbes and heavy metals. The proposed method would even further speed up the rate of production at a lowered cost, produce greater yields of the product compared to extraction procedures / in batch reactions and improve the purity of cannabinoid compounds. This was achieved in flow chemistry whereby the key intermediates (olivetol, a derivative of methyl 6-n-pentyl-2-hydroxy-4-oxo-cyclohex 2-ene-l-carboxylate and cannabigerol) were produced at high conversions (67%, 100% and 34% respectively) in LTF glass microreactors. Cannabigerol was successfully synthesized in flow at high yields compared to literature, however, it was further discovered that the formation of side products was a hindrance to further improvement of the obtained yield in flow. , Thesis (MSc) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
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  • Date Issued: 2022-04

The foraging ecology of female Cape fur seals (Arctocephalus pusillus pusillus) in South Africa

  • Authors: Botha, Jonathan Aubrey , Kirkman, Stephen , Lombard, Amanda
  • Date: 2022-04
  • Subjects: Seals (Animals)--Habitat—Conservation , Marine ecology—South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/55965 , vital:54559
  • Description: The marine environment is spatially and temporally dynamic and many marine ecosystems are experiencing impacts of broad-scale climate change. Within these ecosystems, marine predators play a crucial role in ecosystem function through their top-down influences on prey populations. These predators may also respond to bottom-up influences and changes at lower trophic levels. A thorough understanding of marine predator foraging ecology is thus important to improve our understanding of ecosystem function, inform conservation and management measures, and to predict the response of predators to future environmental change. The Cape fur seal (Arctocephalus pusillus pusillus) comprises a major proportion of the southern African marine predator biomass. However, little is known about the foraging distribution and behaviour of the species, despite its obvious importance within the ecosystem and increasing concerns regarding seal-fisheries conflict. Using a variety of technologies, including, GPS and satellite-linked tags, dive behaviour recorders, accelerometers and stable isotope analysis, this thesis investigated the foraging ecology of female Cape fur seals breeding on the coast of South Africa. First, to identify important foraging areas and assess the influence of geographic, temporal and environmental factors on these areas, lactating females from three breeding colonies were fitted with GPS or Argos-linked tracking devices, while individuals from two of these colonies were also fitted with dive behaviour recorders. Results revealed geographic differences in the foraging distributions and ranges of individuals between breeding colonies, which likely reflects a combined influence of ecological setting and density dependant competition. In addition, dive behaviour recorders revealed the occurrence of benthic foraging at both sites where they were deployed, and the dominance of this strategy in some individuals. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
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  • Date Issued: 2022-04

The Impact of socio-Economic and institutional factors on the Livelihoods of artisanal fisherfolk of Korsten, Gqeberha.

  • Authors: Forbes-Liberty,Abigail
  • Date: 2022-04
  • Subjects: Fishing--Social aspects -- South Africa , Korsten-- Gqeberha
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/55584 , vital:53334
  • Description: his dissertation focuses on a relatively underrepresented group of the fishing industry: subsistence fisherfolk. By using a Sustainable Livelihoods Approach (SLA) and Community Capitals Framework (CCF) as a theoretical framework and interpretive lens, the purpose of this qualitative study is to explore the impact of socio-economic and institutional factors on the livelihoods of artisanal fisherfolk of Korsten, Gqeberha (formerly known as Port Elizabeth). By highlighting the socio-spatial implications of the forced removals of the past, this dissertation shows that legislative reforms should consider the population that they affect. Food security is a major issue on a global scale and South Africa is not impervious to food security concerns. This dissertation focuses on the negative impact that socio-economic climate and legislation has had on subsistence fisherfolk. Hunger and poverty eradication is one of the key goals of sustainable development. In this case, subsistence fishers faced legislative reforms at two distinct points in its tumultuous past, both of which had a detrimental impact on this sector of society's ability to support a healthy livelihood. This research fills a theoretical and practical gap in research regarding the current livelihoods, policies, and laws, as well as provides a deeper understanding of the socio-economic context of the subsistence fishing community of Korsten, Gqeberha. The SLA and CCF helps readers understand how subsistence fishers contribute to local livelihoods and integrate into the greater processes of the community. Further, exploration of the institutional policies limiting subsistence fishers helps understand decision making processes and laws in artisanal fisheries and the implications thereof. A snowball sampling method was used to recruit and enrol participants for this study. The sample size consisted of fourteen (14) participants consisting of eight (8) subsistence fishers and six (6) relatives of subsistence fisherfolk. Narrative analysis is a qualitative method that was conducted in this study. Participant observation and semi-structured interviews were conducted as the methods of data collection and analysed in ATLAS.ti 9 Qualitative Analysis Software. Most participants indicated that fishing plays an integral part of their lives. It contributes to and still ensures the food security in the families of Korsten. In addition, participants highlighted the constant legislative and socio-economic barriers as well as the social and personal benefits of fishing in the community. A key recommendation is made for policy-makers to be cognizant of subsistence fishers and to include this underrepresented group in decision making processes. , Thesis (MSc) -- Faculty of Science, Geosciences, 2022
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  • Date Issued: 2022-04

The potential impacts of hydraulic fracturing on Khoisan peoples’ sense of place: in the case of Karoo Region, South Africa

  • Authors: Tembe, Thandeka
  • Date: 2022-04
  • Subjects: Hydraulic fracturing--Environmental aspects--South Africa--Eastern Cape , Khoikhoi (African people) -- History
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/55701 , vital:53408
  • Description: Hydraulic fracturing is a practical solution to minimising production of fossil fuels and to boost the South African economy. However, this development comes at a cost to the society, environment and heritage of the Karoo, which is home to majority of the Khoisan community. Developments such as hydraulic fracturing are barely understood by local communities therefore this study tried to determine the potential impacts of hydraulic fracturing on Khoisan people’s sense of place in the Karoo region, to also establish their perceptions, attitudes, opinion and knowledge on hydraulic fracturing, to facilitate and improve understanding. A mixed method approach was employed to gather relevant information from participants. The qualitative data collection used semi structured interviews to gain participants perceptions, attitudes, opinions and knowledge on hydraulic fracturing, whereas quantitative used questionnaire survey which was administrated to gain socio-demographics and sense of place of Khoisan people (N=50) using survey based psychometric approach to examine the relationship between Khoisan people and sense of place on proposed hydraulic fracturing in the Karoo region (Cradock). Primary data was employed to gain in depth raw data directly from participants and secondary data from literature that already exists. The purposive and snowball sampling technique was used to draw Khoisan participants from the Karoo region (Cradock). Data acquired was analysed using SPSS v26 and Microsoft excel. The results concluded that most Khoisan participants (N= 43) are not aware of what hydraulic fracturing is and therefore there is a need to be taught about the development. The (N= 7) of the participants who have an idea of what hydraulic fracturing is had attended a workshop that was facilitated by the AEON research institute, others learnt about it on the internet and others were informed by someone who either learnt from the internet or attend the workshop. The study also concluded that the Khoisan people have a strong positive sense of place (α= 0.922) with the Karoo region therefore going ahead with the proposed hydraulic fracturing will cause massive damage and could possibly lead to solastalgia and loss of sense of place. vi The recommendation of the study was to involve all stakeholders who will be part of the development of hydraulic fracturing from government, research institutes to oil and gas companies to thorough research, educate and inform local communities in the Karoo. Therefore, it is essential for the government to protect the Karoo culture and heritage, local peoples sense of place by communicating with local communities on such development and assist in holding these companies reliable for any misconducts. , Thesis (MSc) -- Faculty of Science, Environmental Geography, 2022
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  • Date Issued: 2022-04

The use of psychometric test systems as a pre-selection tool for identifying successful harvesting machine operators

  • Authors: Schwegman, Kylle
  • Date: 2022-04
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/55246 , vital:51102
  • Description: A shift towards fully mechanized forest activities, such as harvesting and, more recently, silviculture, has occurred from the early 2 000’s. The reason for mechanizing these activities differs for each country, although for most countries there is concern relating to the health and safety of forest workers. With mechanization in harvesting, the forest worker has moved away from the physical intensity of having to fell, debranch, debark and cross-cut trees into logs using either an axe or chainsaw, to operating a machine. Studies revolving around the human element (operator) have been conducted specifically relating to the ergonomics of the machines and how operators may influence machine productivity. Results showed that due to the repetitive nature of the work, the operators are exposed to associated stresses for longer periods. Typical injuries associated to these kinds of stressors are whole body vibrations (WBVs), repetitive hand and arm movements, non-neutral body postures and manual lifting, which lead to musculoskeletal symptoms in the lower back, neck and shoulders. However, as machine technology improves so does the ergonomic conditions which are experienced by machine operators. Machine productivity can be influenced by various factors, with the most influential being tree volume. However, a recent study showed that over 40% of variation in machine productivity has been observed amongst different machine operators operating similar machines. The specific reason for these differences has yet to be determined. However, decision making, motivation, planning capacity, concentration, memory, motor coordination, pattern recognition, logic reasoning, and spatial perception are abilities that have been described as important for successful harvesting work. The pre-selection of operators using psychometric and cognitive tests is not new to forestry, although very little information is available relating to the aptitude test known as the Vienna test system as well as the best possible demographic associated with successful harvesting operators. The overall aim of this study was to determine whether the high variation found amongst harvesting machine operators could be reduced initially through a preselection process which involves the use of aptitude tests (Vienna Test System) and demographic questionnaires. A study was implemented in Zululand, South Africa, testing whether there were significant productivity differences between nine machine operators. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Management, 2022
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  • Date Issued: 2022-04

Using information visualization to support the self-management of type 2 diabetes mellitus

  • Authors: Nauder, Meggan Kate
  • Date: 2022-04
  • Subjects: Information visualization , Diabetics --Treatment --South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/55711 , vital:53409
  • Description: The globally increasing number of individuals suffering from Type 2 Diabetes Mellitus (T2DM), a completely preventable incurable disease of the pancreas, highlights the need for an effective tool for users to understand the relationship between their behaviours and the effect that those behaviours can have on their blood glucose levels (BGLs). There are few Information Visualisation (IV) tools available that can be used to reduce the cognition required to understand correlations between behaviour and BGLs. Existing tools require time-consuming, lengthy inputs and provide simple visualisations that do not show correlations. This leads to ineffective self-management of T2DM. Information Visualisation (IV) techniques can be used to support effective self-management of T2DM and reduce the cognition required to interpret DM data. Suitable IV techniques were identified and used to visualize T2DM data to aid in the self-management of the disease. Temporal charts, i.e. The Bar, Pie and Line Chart as well as heat maps, were selected as the most appropriate IV techniques to visualize T2DM data as they support time-series data well. A prototype, MedicMetric was created as an IV tool for visualizing T2DM data. MedicMetric incorporated three designed charts, namely the Change Rate Line View, the Radial Progress View, and the Annotated Line View. The Change Rate Line View and Annotated Line View both used line IV techniques, while the Radial Progress View made use of the bar IV technique. The Change Rate Line View performed the worst overall. A usability evaluation was conducted to compare these techniques and to determine which technique is most suitable for visualizing T2DM data. The results leaned significantly in favour of the Annotated Line View. This view is most similar to the line charts typically used in other IV tools. For this reason, the MedicMetric app was briefly compared to the MySygr and Diabetes:M application. In effectiveness and efficiency, MedicMetric and MySugr obtained almost identical results. However, participants indicated that MedicMetric supported their tasks using the Visual Information Seeking Mantra (VISM) the best overall, with 100% of participants stating that they would prefer to use the MedicMetric application. Several usability problems were identified with the IV techniques and they were addressed shortly after the study was complete. Overall participants were most satisfied with the Annotated Line View. , Thesis (MSc) -- Faculty of Science, Computing Sciences, 2022
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  • Date Issued: 2022-04

Zooplankton dynamics of Algoa Bay (South Africa) under varying oceanographic conditions

  • Authors: Bizani,Mfundo
  • Date: 2022-04
  • Subjects: Marine zooplankton -- South Africa , Climate changes
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/55943 , vital:54554
  • Description: the ecological significance of ocean plankton in terms of nutrient cycling and energy transfer is widely recognised, as is their mechanistic link with both oceanographic processes and climate. Consequently, plankton are widely regarded as sentinels of climate change, principally owing to their responsiveness to changing environmental conditions. Developing an understanding of the ecological as well as socio-economic consequences associated with changes in marine plankton dynamics has emerged as a key issue worldwide. Though many exciting advances in this respect have been attained with the aid of long-term plankton time series (>50 y), global environmental datasets and innovative meta-analyses, building deep knowledge of regional bio-physical dynamics and responses to specific perturbed states remains an essential component of the collective effort. Algoa Bay, situated on the warmtemperate south-east coast of South Africa presents a unique opportunity to study key elements of plankton ecology relevant to climate change problems in the regional sense. The embayment is locally subjected to frequent wind-driven upwelling and regionally, to periodic mesoscale oceanographic forcing (e.g., large solitary meanders, Agulhas Current intrusions), all of which culminate in a complex physical and biogeochemical environment. Using zooplankton as the focal component and drawing from a multi-year monthly dataset incorporating a bay-scale sampling framework, the present study addressed three key hypotheses pertaining to 1) drivers of spatio-temporal variability, 2) biomass rate of change over temporal scales using time-series analyses, and 3) community responses to a bay-scale biological perturbation event. Zooplankton biomass exhibited prominent seasonal patterns with bimodal peaks corresponding with near-consistent year-to-year autumn and spring blooms. Overall, the spatial trend showed no heterogeneity, though statistical significance between-station variability was noted per season. An analytical framework involving generalised additive models revealed zooplankton spatial heterogeneity in Algoa Bay to be a function of seasonal variation in a suite of physicochemical variables, including the combined effects of temperature, salinity, dissolved oxygen, total nitrogen and silicate, but not ammonium, phosphate or chlorophyll-a (as proxy for phytoplankton). Fronts (including river plumes), warm water intrusion from the Agulhas Current, and wind-driven upwelling were postulated to be key driving forces. Structural breaks analysis performed on station-specific time series revealed significant incremental increases in zooplankton biomass over time, which in turn, corresponded with a gradual decrease in thermocline depth. The most pronounced increasing effect was associated with a period (2013– 14) of amplified land-derived nutrient input and increasing harmful algal bloom (HAB) activity. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
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  • Date Issued: 2022-04

A critical exploration of the attitudes towards and knowledge of natural resource management amongst first-year Natural Resource Management students

  • Authors: Jooste, Eileen
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's , text
  • Identifier: http://hdl.handle.net/10948/53666 , vital:45688
  • Description: Available literature suggests that there is a need to gain more understanding of what students’ environmental attitudes and knowledge are and how they are developed by education systems. Education, in general, plays an important role in students’ attitudes and their knowledge of the world around them. It can shape students’ awareness of their natural environment and contribute to their understanding of environmental issues. Education can also strengthen students’ critical thinking, build awareness, stimulate problem solving, and promote sustainable practices. It has the potential to empower students to address global challenges from their own diverse perspectives and prepare them to uphold the economy. Education can improve and maintain societal wellbeing and can help students to maintain the natural environment, along with achieving sustainable development. Environmental education, specifically, can play a big role in how students deal with the natural environment. The primary aim of this qualitative research study was to examine first-year students’ environmental attitudes and knowledge in the School of Natural Resource Management at the Nelson Mandela University George Campus, South Africa. First-year students’ environmental attitudes and knowledge were examined as they entered the university, and then again at the end of the first semester once they had completed a module in ecology. More specifically, at the outset of the research the objectives were (1) to establish an understanding of the baseline environmental attitudes and knowledge of first-year students who were undertaking three ecological modules being offered by the School of Natural Resource Management; (2) to assess the changes in the first-year students’ environmental attitudes and knowledge, using a post-intervention strategy; (3) to understand what type of teaching approaches were used by the lecturers teaching the ecological modules; and (4) to evaluate how the teaching approaches of the lecturers influenced the baseline environmental attitudes and knowledge of the student group. This research took place in the midst of the Corona Virus pandemic, which had significantly influenced the teaching and learning environment. Multiple education systems, including those of the Nelson Mandela University George Campus, had to rapidly transition to online teaching and learning. So, although unplanned for, this research could not ignore the rapid transition to online teaching and learning and the role it played in shaping the first-year School of Natural Resource Management students’ environmental attitudes and knowledge. It also impacted the teaching approaches of the environmental lecturers. An additional objective in response to the rapid transition to online teaching and learning was, therefore, added: (5) to understand the experiences of the first-year School of Natural Resource Management students and the three environmental lecturers who had to rapidly transition to online teaching and learning. Data was collected via questionnaires and semi-structured interviews with students and staff in the School of Natural Resource Management at Nelson Mandela University George Campus within three different natural resource management programs, namely Agriculture, Nature Conservation, and Forestry. Baseline questionnaires were conducted with 107 students for a baseline assessment as the students entered the university. An online post-intervention questionnaire was conducted with 33 of the initial group of students at the end of the semester for a post-intervention assessment. In-depth semi-structured interviews were conducted with three environmental lectures before they taught their three ecology modules in each of the programs. Additional online semi-structured interviews were also done with the same three environmental lectures after the rapid transition to online teaching and learning took place. The significant findings from this research were analyzed and discussed. This included the baseline environmental attitudes and knowledge of the student body upon arrival at the university and the changes in their environmental attitudes and knowledge after they were exposed to the ecology modules taught in each of the programs. The discussion also included the teaching approaches adopted by the environmental lecturers and the influence their teaching approaches had on the students’ environmental attitudes and knowledge. In addition, the results shed light on the experiences of students and lecturers during the rapid transition to online teaching and learning. The main conclusions reached were that the first-year School of Natural Resource Management students did not have a deep understanding of ecological concepts prior to arriving at university, but they did show a concern for the natural environment. Their lack of understanding was reduced as the students progressed with the ecology module. A greater understanding resulted in a change in students’ perspectives on the ecological module, their program, and the industry they were preparing to enter after being exposed to the ecology module. The environmental lecturers’ teaching approaches contributed to improving the students’ environmental attitudes and knowledge. When it came to the rapid transition to online teaching and learning, both the first-year School of Natural Resource Management students and environmental lecturers experienced benefits and challenges. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
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  • Date Issued: 2021-12

A data-driven decision-making model for the third-party logistics industry in Africa

  • Authors: Moyo, Faith
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/53875 , vital:46022
  • Description: Third-party logistics (3PL) providers have continued to be key players in the supply chain network and have witnessed a growth in the usage of information technology. This growth has enhanced the volume of structured and unstructured data that is collected at a high velocity, and is of rich variety, sometimes described as “Big Data”. Leaders in the 3PL industry are constantly seeking to effectively and efficiently mature their abilities to exploit this data to gain business value through data-driven decision-making (DDDM). DDDM helps the leaders to reduce the reliance they place on observations and intuition to make crucial business decisions in a volatile business environment. The aim of this research was to develop a prescriptive model for DDDM in 3PLs. The model consists of iterative elements that prescribe guidelines to decision-makers in the 3PL industry on how to adopt DDDM. A literature review of existing theoretical frameworks and models for DDDM was conducted to determine the extent to which they contribute towards DDDM for 3PLs. The Design-Science Research Methodology (DSRM) was followed to address the aim of the research and applied to pragmatically and iteratively develop and evaluate the artefact (the model for DDDM) in the real-world context of a 3PL. The literature findings revealed that the challenges with DDDM in organisations include three main categories of challenges related to data quality, data management, vision and capabilities. Once the challenges with DDDM were established, a prescriptive model was designed and developed for DDDM in 3PLs. Qualitative data was collected from semi-structured interviews to gain an understanding of the problems and possible solutions in the real-world context of 3PLs. An As-Is Analysis in the real-world case 3PL company confirmed the challenges identified in literature, and that data is still used in the 3PL company for descriptive and diagnostic analytics to aid with the decision-making processes. This highlights that there is still room for maturity into using data for predictive and prescriptive analytics that will, in turn, improve the decision-making process. An improved second version of the model was demonstrated to the participants (the targeted users), who had the opportunity to evaluate the model. The findings revealed that the model provided clear guidelines on how to make data-driven decisions and that the feedback loop and the data culture aspects highlighted in the design were some of the important features of the model. Some improvements were suggested by participants. A field study of three data analytics tools was conducted to identify the advantages and disadvantages of each as well as to highlight the status of DDDM at the real-world case 3PL. The limitations of the second version of the model, together with the recommendations from the participants were used to inform the improved and revised third version of the model. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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  • Date Issued: 2021-12

A spatial assessment of riparian vegetation density and implications for streambank erosion in relation to land tenure in the Mgwalana Catchment, Eastern Cape Province, South Africa

  • Authors: Maxama, Asakhile
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/53864 , vital:46026
  • Description: Riparian vegetation provides an array of various ecosystem functions and has significantly shaped the conditions of catchments. It has strong controls on fluvial geomorphology and erosion processes. The Mgwalana catchment has been intensively studied over the years and the current environmental condition of the study has been linked to land use history. The catchment has been subjected to land use/cover changes (LUCC) over the years. However, spatial variations in riparian vegetation, their implications for stream bank stability and the contribution of land tenure systems to stream channel degradation are poorly understood. The study sought to assess the implications of the spatial variations in riparian vegetation density for stream bank erosion in relation to land tenure on a catchment scale. Land tenure units comprising the catchment of study are traditional and betterment villages (communal lands), and former white commercial farms. A three-pronged approach using GIS and remote sensing, field investigations and laboratory procedures for soil analysis was employed in this study. Variations of riparian vegetation density in the catchment were mapped using ArcGIS for the two land tenure units to assess the spatial variations of riparian density along stream reaches and to determine the spatial relationship between land tenure units and riparian vegetation diminution. Other mapped shape files include sediment accumulation zones to analyse the spatial relationship between riparian vegetation density and sediment sinks. LUCC classification and analysis of the Normalized Difference Vegetation Index (NDVI) were carried out in IDRISI Selva, using Landsat 8 TM imagery of 2018 to represent the current spatial riparian vegetation variations in the catchment. Field investigations were conducted to determine the coupling among hillslope gully erosion, riparian vegetation density and sink areas; and to assess physical characteristics of soil. This would permit an assessment of the implications of riparian vegetation for stream bank erosion and sediment accumulation within the tenure units. Soil samples were taken from scantily and densely vegetated stream reaches, as well as measurements of channel widths and depths. Analyses of soil physical properties viz; grain size distribution, bulk density, soil texture and aggregate stability were done. Results demonstrated that a sparse riparian vegetation distribution was consistent with the communal villages, confined to the upper catchment area. Dense riparian vegetation distribution was consistent with former commercial farms in the lower catchment area. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-12

A value alignment smart city stakeholder model

  • Authors: Van der Hoogen, Anthea Vivian
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/54129 , vital:46309
  • Description: The concept of a Smart City has evolved over the last three decades and has attracted the increasing interest of the scientific research community. Unfortunately, many Smart City projects and initiatives do not provide the value expected by all the stakeholders. Many of the reasons for this relate to a lack of data management, data integration, data access and stakeholder participation. People are an integral part of any city’s ecosystem, and the Smart City concept was introduced to address the challenges of an ever-growing global population leading to the risk of depletion of economic, environmental and social resources. The problem addressed in this study is based on the challenges preventing the creation of the value of smart cities or stakeholders. Limited research has been published on the status of Smart City initiatives or on the impact of various success factors on the potential value creation for stakeholders including citizens. Studies on initiatives in developing countries, such as South Africa are even less. Whilst some challenges and constraints related to smart cities in Africa have been reported, there are no studies reporting on initiatives across the data value chain that consider all types of stakeholders, nor the impact of these initiatives. This study addressed this gap in research and designed a theoretical Value Alignment Smart City Stakeholder (VASCS) Model based on a Systematic Literature Review and a review of related theories. The model has important components that should form part of any Smart City project or Smart City initiative. These five main components are: 1) nine Smart City dimensions with related success factors; 2) four stakeholder roles (enablers, providers, utilisers and users); 3) the data value chain; and 4) the five phases of stakeholder benefits/value realisation that can be linked to; 5) stakeholder value alignment. This study applied the VASCS Model to Smart City initiatives in two case studies in the Eastern Cape Province of South Africa, which were the Nelson Mandela Bay and Buffalo City to investigate and understand the status of such initiatives and the alignment of value thereof. The stakeholder interviews were conducted in two rounds with various stakeholders of Smart City initiatives, referred to as cases in the two case studies. An expert review of the VASCS Model was conducted with eight experts in the field of Information Systems and Smart Cities. The findings of this review served to confirm the components of the model, with only minor improvements recommended. It was confirmed that all of the components need to be considered in planning Smart City projects. The first round consisted of six interviews with enablers and providers and the second round consisted of 22 interviews with users, utilisers and citizens. The interviews investigated the value and impact experienced by stakeholders of these initiatives, with a particular focus on the users, utilisers and citizens of the cases. The interview data was transcribed and qualitatively analysed by using Atlas.tiand Excel. The data was analysed according to the Technological, Organisational and Environmental theory constructs and other identified themes. The interview analysis findings revealed several drivers for these initiatives, which were primarily cost reduction, integration and quality assurance. The results also highlighted access to resources, such as technical skills as a challenge. Another challenge identified was connectivity related to access to data and the digital and physical divide that can impact decision making. The main benefits of Smart City initiatives highlighted were the provision of infrastructure, education and training and digitalisation. The theoretical contribution of this study is the VASCS Model, which can assist other researchers and practitioners with knowledge of the factors, drivers, challenges and value obtained in Smart City initiatives. The model has two supplementary components: A Stakeholder Classification Model and a Smart City Success Factor Evaluation Template. The practical contribution of this study is the potential use of the VASCS Model by practitioners, city management, researchers and other stakeholders, who can use the model, with the related model and template for planning and evaluating Smart City initiatives. The model can be used to classify the digital activities according to a Smart City’s success factors while evaluating the value created by these activities. The impact of these initiatives can then be assessed through value realisation and alignment for stakeholders. The scientific contribution is the adoption of the model to the cases in the Eastern Cape. To reveal in depth, rich, interview findings that provide important lessons learnt relating to the value created for the stakeholders and the addition of these findings to the body of knowledge. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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Applying a systems analysis approach to support marine spatial planning in Algoa Bay, South Africa

  • Authors: Vermeulen, Estee Ann
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/54121 , vital:46312
  • Description: Ocean health provides the foundation for human health through the provisioning of ecosystem services. Increasing demands on ocean space and resources are, however, resulting in a decline in ocean health, with direct and indirect knock-on effects on marine uses and ultimately on human health. In response, there is a growing need to acknowledge and better manage complex human-ocean interactions. This has been recognised in global sustainable development goals and in integrated ocean management processes, leading to widespread endorsement of an ecosystem-based marine spatial planning (MSP) process, including in South Africa. In support of the national MSP process, significant progress has been made in understanding the spatial extent of marine activities and associated marine pressures, but the temporal dynamics of marine activities and interconnections with the marine environment are less well understood. To plan for the growth of marine activities and associated user conflicts, the drivers of these temporal dynamics and associated feedback effects need to be analysed and potential policy and management interventions identified and tested. To support South Africa’s national MSP process, this study adopts a systems analysis approach, using system dynamics modelling, to explore the temporal change in marine uses under alternative growth scenarios in Algoa Bay. Algoa Bay is an appropriate study area because it is experiencing a rapid expansion of marine activities, coupled with a growing uncertainty regarding marine sustainability outcomes. To assist future marine management decisions, the Algoa Marine Systems Analysis Tool (Algoa MSAT) was developed, comprising seven sub-models. Five of the sub-models represent selected marine uses in Algoa Bay, whereas the sixth and seventh integrate the outputs from each marine use in terms of sustainable management indicators (marine health, marine wealth and marine labour). Model development primarily adopted an expert-based model ling approach, although the involvement of stakeholders, through a collaborative modelling process, assisted in integrating knowledge on different marine sectors’ activities, impacts and planning visions into the model framework. Model results were generated under different scenarios to investigate changes in the growth of marine activities and marine sustainability indicators under different levels of ocean governance. Under the baseline (or business-as-usual) model scenario, marine activities were shown to grow increasingly within their respective management limits, with an increase in marine wealth and labour and a consequential decrease in marine health. This scenario particularly highlights that current ocean governance practices are ineffective in sustaining the projected growth of the marine uses, particularly for those that are vulnerable to negative changes in marine health. Conversely, sectors that hold more value in marine wealth and are more resilient to changes in marine health, may continue to grow regardless of negative knock-on effects of the health of the marine environment and on other uses in the bay. This emphasises that an alternative governance strategy is needed to achieve the long-term goal of an ecosystem-based MSP process, as required by South African MSP legislation. To achieve this will require multiple, adaptive cross-sectoral management interventions that are directed towards the ‘deeper leverage points’ that are able to maintain the growth of marine activities within appropriate limits defined by marine health. Using the model interface developed in this project, decision-makers and stakeholders can use the model to explore the temporal dynamics in marine activities under different governance scenarios. Although the model is limited to Algoa Bay, the model boundary can be adapted to assist in marine planning processes at national or trans-national scales. Such analytical assessments and tools are critical to progress the ecosystem-based management approach in MSP, as is required to achieve global sustainable development goals. , Thesis (PhD) -- Faculty of Science, Coastal and Marine Research Unit, 2021
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  • Date Issued: 2021-12

Beneficiation of pyrolysis-derived waste tyre char by blending with torrefied wood and microalgae to produce solid fuel

  • Authors: Dube, Cleopatra Thulani
  • Date: 2021-12
  • Subjects: Pyrolysis , Solid fuel reactors
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/58439 , vital:59241
  • Description: he thermal decomposition of waste tyres via pyrolysis is considered to be amongst the most promising methods of recycling tyres due to its minimal environmental impact (in terms of reduction in pollution). During pyrolysis, tyres are thermally degraded in an inert environment to produce gas, oil and char. The gas and oil have promising commercialization prospects while the char remains a pollutant despite the strides made in a lot of research to upgrade the char to carbon black, activated carbon and even for reuse as a filler in tyre manufacture. For pyrolysis to be profitable, or worthy of investments, all three of its products (oil, char and gas) need to be valorised. Pyrolysis-derived tyre chars (PT-char) have an energy value equivalent to high rank coals, however, the use of PT char as a solid fuel is uncommon due to the high contents of sulphur and mineral matter as well as low volatile matter content of the PT-char. As such, the combustion of PT-char is characterised by high ignition temperature, low thermal reactivity, and no flame formation due to the low amounts of volatile matter. On the other hand, biomass are clean, renewable feedstock, having low sulphur and mineral matter contents, as well as high thermal reactivity. The blending of PT-char with biomass could potentially improve the combustion properties of PT-char and minimise the release of toxic emissions from the char, and thus, could make PT-char suitable for use as a fuel source. In this study, PT-char was blended with torrefied wood and microalgae biomass to demonstrate the suitability of using PT-char-biomass-fuel blend as an energy feedstock. To this effect, a mixture design of experiments was used to formulate the PT-char biomass blends and regression analysis was employed to select an optimum blend formulation for the combustion and mechanical properties of the blends. Proximate analysis results showed a non-linear increase in the volatile matter and a non-linear decrease in the fixed carbon and ash yield as the biomass ratio increased. The calorific value also increased on an additive basis with increasing biomass proportion. The elemental analysis results showed a decrease in the calcium, zinc and bromine contents and an increase in the potassium and iron contents increased with increasing biomass proportion. Likewise, the sulphur content decreased while the oxygen, hydrogen and nitrogen contents increased with increasing biomass ratio. vi Thus, the fuel properties of the blends improved with increasing biomass ratio and without compromising the calorific value of the PT-char. Moreover, the TG-MS analysis showed that the PT-char and the respective blends did not show any release SO2 up to 650°C. Thus, making the fuel suitable for use in low temperature applications such as household and certain boilers. The results of the regression analysis showed that the blend formulation with the highest proportions of biomass, thus C55-T30-M15, is the optimum blend to produce a solid fuel with a low initial decomposition (214°C) and char ignition temperatures (532°C) as well as maximum burn-out temperature (640°C). In essence, the high thermal reactivity of PT-char is improved when both biomasses are loaded at maximum ratios as per the experimental design. The results of the MS showed a decrease in CO2 and NO2 emissions with increasing biomass proportion. The optimum blend (C55-T30-M15) was found to have a comparably higher gross calorific value (26 MJ/kg), lower sulphur content (1.1 wt.%), low ash yield (11wt.%) and lower concentration of minerals (i.e. zinc) than raw PT-char. In addition, the volatile matter content of the blend (20 wt.%) was found to be higher than that of PT-char and the ignition temperature of the optimum fuel blend was relatively lower and its burnout temperature higher than that of PT char. The MS results revealed that the CO2 and NO2 emissions were higher in the optimum blend than the PT-char. The mechanical properties of the pellets; impact resistance and compressive strength increased with increasing biomass blending ratio and even more so with increasing microalgae ratio. The C55-T30-M15 and C75-T10-M15 were selected as optimum blends using regression analysis and both blends exceeded the benchmark for mechanical properties except for water resistance. The blending did not improve the water resistance and all the blends did not meet the minimum threshold for water resistance. Overall, the blending of PT-char with torrefied wood and microalgae biomass has shown to improve the fuel properties PT-char, and therefore, making it a suitable potential fuel source. , Thesis (MSc) -- Faculty of Science, 2021
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  • Date Issued: 2021-12

Coordination polymers for denitrogenation of fuel oils

  • Authors: Dembaremba, Tendai O
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/53630 , vital:45682
  • Description: In this thesis, we present adsorptive removal of nitrogen-containing compounds from fuel oil as an alternative to complement conventional hydrotreatment to obtain ultra-low sulfur and nitrogen levels. This is in cognizance of the challenges nitrogen-containing compounds pose to the hydrotreatment process, particularly their inhibition and/or poisoning of the catalysts used in the process, of which basic nitrogen-containing compounds are the major culprits. Selectivity is the biggest challenge for adsorptive removal of nitrogen-containing compounds. We explore reticular synthesis of metal organic frameworks and the use of coordinatively unsaturated metal sites in 1-dimensional coordination polymers to achieve good selectivity for nitrogen-containing compounds. In the first part of the thesis, reticular synthesis of metal organic frameworks to control the size of the cavity, and strategically use the linkers and metal centres was envisaged. In this work we explored variation of the metal centres in the secondary building units (SBUs of the MOFs as the first step to the testing and implementation of the design strategies. Carbazole, representing carbazoles which the major compounds that remain in hydrotreated fuel, was the target compound. Four MOFs of zinc (Zn-CDC-bpe), copper (Cu-CDC-bpe), nickel (Ni-CDC-bpe) and cobalt (Co-CDC-bpe) based on the formation of a dinuclear metal paddlewheel SBUs with the ligand 9H-Carbazole-3,6-dicarboxylic acid (H2CDC) and occupation of the axial positions of the paddlewheel by 1,2-Bis(4-pyridyl)ethane (bpe) to form porous networks were synthesized. A fifth MOF containing only CDC which forms a [Zn4O(O2C-R)5(O2HC-R)] SBU was also synthesized (Zn-CDC). The ligand H2CDC was inspired by the possibility of improving selectivity for carbazole via π–π interactions through the more preferred parallel-offset stacking as well as the possibility for further substitution of the carbazole N-H to add groups that improve selectivity. The sizes of the MOF cavities can then be controlled by choosing different lengths of ligands analogous to 1,2-Bis(4-pyridyl)ethane (bpe), e.g. 4,4’-bipyridine and pyrazine. All the MOFs showed good selectivity of carbazole. The Zn-CDC MOF also had good selectivity for the basic nitrogen-containing compounds tested: quinoline, isoquinoline, quinaldine and 1-naphthylamine. Its uptake of carbazole was also slightly higher. This was attributed to the presence of an unsaturated Zn site in the SBU. Adsorption in all the MOFs was primarily due to physisorption. It was concluded that the role of the metal centre does not play a significant role in the adsorption of carbazole besides providing a template for reticular synthesis. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
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  • Date Issued: 2021-12

Corrosion and hydrogen resistant modified zirlo surfaces for nuclear fuel cladding

  • Authors: Ngongo, Sinoyolo
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/54077 , vital:46252
  • Description: Zirconium (Zr) alloys are used as fuel cladding material in all modern water cooled commercial nuclear reactors. Zr alloys have many desirable properties for the nuclear reactor core environment, however, it also has a weakness in that overheated zirconium alloy fuel rods react with hot steam resulting in the release of hydrogen. High temperatures increase the oxidation rate and hence the hydrogen production rate which in turn increase the risk of a hydrogen gas explosion such as what is surmised to have happened in the 2011 Fukushima Daiichi nuclear plant incident. The some of the hydrogen produced will also diffuse into the zirconium alloy and form zirconium hydrides which will weaken the original zirconium alloy material. The development of accident tolerant fuel became a major focus area after the Fukushima event in March 2011 with the U.S. congress directing the U.S. Department of Energy to develop fuel with enhanced accident tolerance at high temperatures. The main objective in the case of zirconium alloy cladding has been the modification of cladding surface layers by coating or doping in order to reduce the oxidation rate and hydrogen generation rate by the reaction of steam with zirconium alloy cladding at high temperatures. This thesis focuses on two surface modifications to decrease the surface corrosion rate of ZIRLOTM (the Zr alloy used in this study) and reduce hydrogen uptake by ZIRLO. The first modification involves an oxidation-resistant nano-crystalline diamond (NCD) film deposited on ZIRLO. The NCD layer was deposited in a microwave plasma-enhanced linear antenna chemical vapor deposition (MW-LA-PECVD) system after immersion of the ZIRLO tubes in a water-based solution containing nanodiamonds. ZIRLO tube samples were coated with 200 nm and 500 nm thick NCD layers. The 200 nm thick NCD coated ZIRLO was kept as control sample whereas the 500 nm thick NCD coated ZIRLO was exposed to steam oxidation at 360 °C for 90 days. The results revealed that the NCD exfoliated in some areas leaving the ZIRLO exposed to the steam. In the areas where the diamond did not exfoliate, the diamond was still attached to the ZIRLO with an amorphous carbon layer present between the NCD and the zirconium oxide layer.The transmission electron microscopy (TEM) results of this study indicate the presence a sp3 – hybridised diamond phase for the NCD layer as well as an intermediate amorphous carbon layer between the NCD and ZrO2 layers. Analyses of the area where the NCD layer had exfoliated showed no evidence of an NCD layer. It is possible that the amorphous carbon layer between the diamond and the zirconium oxide is responsible for weak interfacial bonding leading to partial exfoliation during oxidation in steam 360 °C for 90 days. In the second modification, the effectiveness of a Cr doped ZrO2 layer to reduce the migration rate of hydrogen in ZrO2 was investigated. The ZIRLO tube used for this part of the study did not have a thin oxide passivation surface layer. Two different procedures were used to create chromium doped zirconium oxide surface layers on ZIRLO. The ZIRLO surface was coated with chromium using cathodic arc deposition followed compression plasma flow (CPF) treatment to facilitate intermixing of the Cr and the ZIRLO. In procedure 1, the surface modification was achieved through the incorporation of chromium into the zirconium surface layer using a compression plasma flow (CPF) technique, followed by the oxidation of the chromium doped zirconium. The oxidation process was conducted at 500 °C for 6 hours. In procedure 2, the chromium was incorporated into the zirconium oxide layer again using the CPF technique. Hydrogen desorption was measured from pure ZIRLO and CPF modified samples using a special gas reaction controller system. The key finding of the results is that the chromium doped (incorporated) zirconium oxide layer on ZIRLO sample exhibited the lowest hydrogen desorption rate of all the samples analysed. This indicates that H in the Cr doped zirconium oxide layer had the lowest mobility of all the samples investigated. This is consistent with the theoretical predictions that the doping of ZrO2 by Cr reduces the solubility of hydrogen in ZrO2. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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  • Date Issued: 2021-12

Effect of coal and microalgae biomass co-firing on CO2, SO2 and NOx emissions: An experimental evaluation

  • Authors: Magida, Nokuthula Ethel
  • Date: 2021-12
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/53817 , vital:45984
  • Description: There is increasingly stringent legislation on the environmental impact of energy production from coal combustion, and this has led to growing pressure to reduce the emission of greenhouse gases (GHGs). Thus, there is a significant need to develop and implement clean coal combustion technologies that would reduce the environmental gas pollutants. For power generation, the co-firing of biomass fuels at conventional coal-fired power stations is recognised as one of the low-cost, low-risk options to achieve significant reductions in GHG emissions. When coal is co-utilized with biomass there is added attractiveness because the biomass is CO2 neutral, and there is interest in using waste biomass and microalgae. Thus, the co-combustion of coal and biomass for energy production results in pollutant reduction, especially in the emissions of NOx, SOx, volatile organic compounds and polyaromatic hydrocarbons. The synergistic activity observed for toxic organic emissions is not well understood and is thought to involve chemical interaction between the volatiles from each fuel coupled with possible catalytic activity from the inorganic constituents of the fuels. The characterization of co-firing products and gases emitted from coal and microalgae (particularly the Scenedesmus strain) co-combustion has received limited attention. Therefore, this study seeks to understand possible interactions occurring during co-combustion of coal and Scenedesmus microalgae (Coalgae®). Additionally, the study aims to determine the effect of co-firing coal and Scenedesmus microalgae on CO2, SO2 and NOx emissions. The term “Coalgae®” refers to the mixture of coal and microalgae biomass. The study looks at physico-thermal characteristics as well as CO2, SO2 and NOx emissions of various coal-microalgae blending ratios by mass; 100:0 (coal), 95:5 (Coalgae® 5%), 90:10 (Coalgae® 10%), 85:15 (Coalgae® 15%) and 80:20 (Coalgae® 20%). Characterization techniques carried out included proximate and ultimate analyses, Fourier-transform infrared (FT-IR) and Scanning electron microscopy and X-ray energy dispersive spectroscopy (SEM/EDS). For combustion studies two techniques were applied. Low heating rate was obtained through a Thermogravimetric-Mass spectrometer analysis (TG-MS). Other combustion experiments were performed on the five lumpy fuels (coal and Coalgae® 5% - 20%) exposed to the flame in a fixed-bed combustion reactor. The emission concentrations of CO2 (%), NOx (ppm) and SO2 (ppm) of coal and Coalgae® blends were measured during the combustion of the five materials using a Lancom 4 portable flue gas analyser. The mass reduction (g) and temperature (°C) at the reactor exit were recorded during the combustion tests to compare the combustion behaviour of the four mixtures to that of raw coal. TG-DTG curves of coal and microalgae confirmed that the combustion behaviour of these materials was different. Coal showed one reaction during the combustion process, while microalgae and the Coalgae® blends showed three reactions. A significant reduction in activation energies of 160.4 kJ/mol, 159.6 kJ/mol, 151.3 kJ/mol, and 134.2 kJ/mol for Coalgae® 5% - Coalgae® 20%, respectively, compared to coal (161.3 kJ/mol) was achieved. The lowering of activation energy could be attributed to the relative fixed carbon content. SEM morphology images of ash obtained from the combustion of coal and Coalgae® 5% - 20% confirmed changes in devolatilization and combustion behaviour of solid raw fuel. The ash of Coalgae® blends had higher fluxing elements (Fe, Ca, K and Mg) than coal and this shows possibility of slagging and fouling in combustion systems. The Coalgae® blends showed a synergistic effect due to different combustion characteristics of coal and Scenedesmus microalgae. The combustion results obtained from the fixed-bed reactor showed significant reductions in concentrations of CO2, SO2 and NOx emissions for Coalgae® blends compared to baseline coal. Microalgae reduced CO2 emissions from baseline coal by 14.9%, 19.5%, 23.5% and 31.4% for Coalgae® 5%, 10%, 15% and 20%, respectively. SO2 reductions of 1.9%, 10.6%, 15.8% and 18.2%, and NOx reductions of 22.4%, 26.1%, 24.4% and 16.9% were achieved with Coalgae® 5%, 10%, 15% and 20%, respectively. Moreover, the combustion efficiency of Coalgae® blends increased significantly by up to 14.5% from baseline coal (86.4%) to Coalgae® 20% (98.9%). Based on the above findings, the co-firing of coal and Scenedesmus microalgae biomass was necessary for the reduction of CO2, SO2, and NOx emissions. As such, Coalgae® blends can be considered as alternative fuels in any coal driven process for energy generation. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
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  • Date Issued: 2021-12
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