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Synthesis, assessment, and application of two-dimensional ferromagnetic nanocomposites for the removal of microplastics from drinking water and wastewater effluent
No full textSubmitted in Fulfilment of the requirements for the Degree of Doctor of Philosophy in Biotechnology at the Durban University of Technology, Durban, South Africa, 2025.The increase in microplastics (MPs) concentration in water matrices continues to pose a serious
threat to aquatic ecosystems, and subsequently human health as a result of bioaccumulation
within these aquatic organisms. Significant number of MPs have been detected from different
water matrices including surface water and wastewater treatment effluent, globally. Recent
reports from South Africa have also indicated their presence in tap water in low concentrations.
Water treatment plants globally, are not optimised or designed for the removal of MPs.
Therefore, technological innovations are required to alleviate the limitations embedded in these
treatment systems. Nanotechnology has emerged as a pivotal technology to address a wide
range of environmental challenges through performance enhancement. Therefore, this study
investigated the removal of MPs from aquatic environments using magnetic nanocomposites
(MNCs). This is the first study to the best of our knowledge that explicitly evaluates the
performance of MNCs g-C3N4@Fe3O4 and BNNS@Fe3O4 for the removal of MPs. Herein, the
application of each MNC is assessed for their removal efficiency of individual and
multitudinous combinations of polystyrene (PS) and polyethylene (PE) MPs, including
different size ranges. Additionally, these MNCs are applied in drinking water and real domestic
wastewater effluent to determine their effectiveness against a combination of PS and PE MPs.
Furthermore, a phytotoxicity study was also conducted to assess the toxicity of g-C3N4@Fe3O4
and BNNS@Fe3O4 on various common agricultural crops (Hordeum vulgare L. (barley wheat),
Cicer arietinum (black chickpea) and Vigna radiatus L. (moong)). The recyclability study was
performed for five successive rounds of reuse and each of the MNCs magnetic stability was
assessed via VSM. Finally, a cost assessment analysis for MPs removal with the best performing MNC (g-C3N4@Fe3O4) was also conducted as well as the mechanistic insights of
the interactions between PE/PS MPs and the MNC was postulated.
The MNCs (g-C3N4@Fe3O4, BNNS@Fe3O4) were synthesized by conventional co precipitation. Synthesized MNCs were characterised by various analytical techniques such as,
XRD, TGA, FTIR, BET, XPS, SEM-EDX, TEM, VSM, and Zeta potential. The optimization
of various parameters (pH, time, MNC dose, MP dose) were done through gradient
experiments. Optimised parameters were applied in batch experiments to investigate g C3N4@Fe3O4 and BNNS@Fe3O4 for the removal of different types and sizes of MPs (PE (125
µM), PS (25-180 µM), PE+PS combo (PE=125 and 25-180 µM) and PS (180-500 µM) from
Milli-Q water, wastewater effluent and drinking water.
The maximum removal of PE (96.16%, size 125 µM), PS (92.5% , size 25-180 µM), PE+PS
combo (94.89%, size PE=125 and 25-180 µM) and PS (45.62%, size 180-500 µM) were
noticed with MNC g-C3N4@Fe3O4 under optimum operating conditions ([pH]= 4; time= 5 h;
[MNC]= 1.2 g/L; [MP]= 0.5 g/L) from Milli-Q water. The maximum removal efficiency of
PE (94.44%, size 125 µM), PS (85.96%, size 25-180 µM), PE+PS combo (88.28%, size
PE=125 and 25-180 µM) and PS (38.77%, size 180-500 µM) were observed with MNC
BNNS@Fe3O4 under optimum operating conditions ([pH] = 3; time= 12 h; [MNC]= 0.9 g/L;
[MP] = 0.5 g/L) from Milli-Q water. A direct correlation was observed between the removal
rate and the size of the MPs. The investigation of MNC removal efficiency in different water
matrices yielded 93.7 and 86.56% from drinking water via g-C3N4@Fe3O4 and BNNS@Fe3O4,
respectively. A removal rate of 91.91 and 83.78% was observed from domestic wastewater
effluent filtered with a 0.22 µM filter for g-C3N4@Fe3O4 and BNNS@Fe3O4, respectively,
whilst a removal rate of 90.28 and 82.23% was observed from the same domestic wastewater
effluent (unfiltered) for g-C3N4@Fe3O4 and BNNS@Fe3O4, respectively. The results for
filtered and unfiltered wastewater effluent are similar indicating that filtering plays no
significant role in improving the removal efficiency. The reusability study revealed that both MNCs retained a removal efficiency of more than 50% after 5 cycles whilst g-C3N4@Fe3O4
retained a removal efficiency of almost 80% after 3 cycles. The VSM results exhibited that
both MNCs possess superparamagnetic behaviour which indicates that both BNNS@Fe3O4 and
g-C3N4@Fe3O4 have excellent magnetic properties, enabling their application in practical
settings. This was further confirmed by the after-treatment results wherein both MNCs retained
their superparamagnetic properties after adsorption of the MPs, allowing for effective magnetic
separation.
MNCs' phytotoxicity on common agricultural crops was assessed to investigate any potential
ecotoxic effects on the crops. The phytotoxicity of domestic raw wastewater influent, final
treated effluent, g-C3N4@Fe3O4, BNNS@Fe3O4, g-C3N4@Fe3O4 filtrate and BNNS@Fe3O4
filtrate were assessed through seed germination indices (G.I.%). The MNC filtrate of g C3N4@Fe3O4 and BNNS@Fe3O4 revealed mild toxicity (approaching non-toxic) and no
toxicity, respectively. The operating cost of g-C3N4@Fe3O4 for MPs removal from domestic
wastewater effluent was approximately 41.09$/m3
. This makes it is a cost-effective treatment
when compared to literature. The four main potential interactions postulated to occur between
the PS/PE MPs and g-C3N4@Fe3O4 and BNNS@Fe3O4 MNCs are: electrostatic interaction, π π interaction, Van Der Waals forces and hydrogen bonding.
In conclusion, this thesis demonstrates the promising potential of MNCs (g-C3N4@Fe3O4 and
BNNS@Fe3O4) for the efficient removal of MPs from various water matrices, including
drinking water and final treated wastewater effluent. The remarkable removal efficiency and
superparamagnetic properties of these materials, coupled with their low environmental toxicity
and cost-effectiveness, highlight their feasibility for practical applications. This thesis further
confers the understanding of g-C3N4@Fe3O4 and BNNS@Fe3O4 MNCs recyclability, therein
promoting a circular economy and a sustainable approach for wastewater treatment. These findings contribute to advancing sustainable wastewater treatment solutions and address the
global challenge of MP pollution
Evaluation of enhancement methods for the production of biogas for anaerobic codigestion of sewage sludge with industrial wastewater
No full textSubmitted in fulfilment of the requirements for the degree of Master of Engineering: Chemical Engineering, Durban University of Technology, Durban, South Africa, 2024.The worldwide move towards a sustainable, equitable future faces two major obstacles:
unsustainable waste management and access to clean energy (Kwietniewska and Tys, 2014).
Alternative renewable energy sources are needed to curb global warming and the consumption
of non-renewable fuels (Akinbami et al., 2021). Industrial and municipal wastewater with high
organic matter content has increased due to rapid industrialisation in many emerging nations.
If appropriately treated, wastewater may produce biogas through anaerobic digestion to
generate green energy (Chrispim et al., 2021). While anaerobic digestion is a mature
technology, challenges around process efficiency remain. Thus, much research has examined
ways of enhancing anaerobic digestion (AD) efficacy.
This research evaluated the suitability and investigated the effects of intermediate municipal
landfill leachate and sugar industry wastewater as co-substrates in the AD of sewage sludge.
The effects of biochar addition synthesised from sugarcane bagasse at three pyrolysis
temperatures (3500C, 4500C and 5500C) together with ultrasonic pretreatment as a potential
enhancement method were evaluated with respect to four key performance indicators: (I)
biogas yield, (II) biogas quality, (III) COD and (IV) Volatile Solid (VS) removal.
Response surface methodology (RSM) was employed to evaluate the following specific
objectives: Five objectives were evaluated: (i) Characterization of primary sewage sludge,
inoculum, and industrial wastewater. The total solids (TS) and volatile solids (VS) for PS were
39.02 (gTS/l) and 29.72 (gVS/L), respectively, falling within the expected range. The results
also suggest that the sludge exhibits excellent biodegradability, evidenced by a VS/TS ratio
of> 50%. Sugar industry wastewater (SIWW) exhibited a VS/TS ratio of 0.68, indicating a
greater presence of organic substances than insoluble ones. The inoculum displayed the lowest
VS/TS value, measuring 0.48, indicating a high concentration of microorganisms vs organic
materials, confirming its potential use as an inoculum rather than as a substrate. (ii) Production
and characterisation of biochar (BC) derived from sugarcane bagasse using energy dispersive
x-ray, scanning electron microscopy (EDX/SEM), and Fourier transform infrared spectroscopy
(FTIR). The BC synthesised at 5500C was the most alkaline at a pH of 9.1, followed by 9.0
(BC 4500C) and 7.0 (BC 3500C). While all the synthesised BC displayed carbon contents > 50
%, BC 5500C exhibited the highest at 78.33%. SEM analysis found BC 4500C exhibited greater
formation of surface micropores. FTIR analysis of the BCs confirmed the presence of carboxyl,
carbonyl, carboxyl, hydroxyl, C=N bond, and ether group. (iii) Investigate the effect of Municipal Intermediate Landfill Leachate (ILL) and Sugar Industry Wastewater (SIWW) as
co-substrates and optimisation of process parameters with RSM. This was executed in two
stages; the first was employed to identify the best-performing IWW. ILL produced the highest
biogas yield at (54,35 mL/gVSadded) vs (12.55ml/gVSadded) for SIWW; ILL achieved the highest
COD removal (46.84%). ILL was found to increase the COD removal by 5.36% compared to
the CNTRL. Hence, ILL was selected as the best-performing co-substrate for process
optimisation. Optimisation facilitated by (RSM) employing Box–Behnken design with cosubstrate loading between (1:20 – 1:5), ISR (1:2– 1.5:1) and temperature (25 – 550C), the
optimum co-substrate loading of (1:20), ISR of (1.5:1), and a temperature of 370C, achieved
desirability of 90.10%. The RSM-BBD models exhibited a significant correlation (0.9 < R2 <
1) with projected outcomes that aligned well with the experimental data. (iv) Investigate the
effect of Biochar as an additive on the AD process. This was executed in two stages; the first
was employed to identify the best-performing BC. BC 450 produced the highest biogas yield
at (50.38mL/gVSadded) vs (46.88 and 26.57mL/gVSadded) for BC 3500C and BC 5500C,
respectively; BC 4500C also achieved the greatest COD and VS removal of 50.86% and
35.11%, respectively. Hence, BC 450 was selected as the best-performing BC for process
optimisation. Optimisation with co-substrate loading between (1:20 – 1:5), BC loading (2.5 –
10 g/L) and temperature (25 – 550C), the optimum co-substrate loading of (1:20), BC loading
of (6.7 g/L), and a temperature of 54.990C, achieved desirability of 94.10%. The RSM-BBD
models exhibited a significant correlation with projected outcomes that aligned well with the
experimental data. (v) Investigate the effect of ultrasonic pre-treatment of industrial wastewater
on the anaerobic digestion process. ILL was subjected to ultrasonic pretreatment and codigested employing the optimum process parameters from (iv) Process efficiency was assessed
with respect to biogas yield, COD and VS removal and biomethane content and achieved a
COD and VS removal of 46.18% and 49.21, respectively. The biomethane content peaked at
78.23% CH4. Representing a marginal decrease in COD and VS removal compared to the
untreated sample.
Application of cold plasma for inactivation of waterborne pathogens
No full textSubmitted in fulfilment for the Degree of Master of Applied Science in Biotechnology, Durban University of Technology, Durban, South Africa, 2025.The inactivation of harmful pathogenic microorganisms during water treatment is
essential for ensuring safe and clean water for human consumption. Current
treatment technologies exhibit limitations in effectively eliminating pathogenic
contaminants, necessitating the exploration of advanced disinfection
technologies. This study investigates the application of atmospheric cold plasma
(ACP) as a novel disinfection method for water contaminated with various
pathogens, optimising key treatment parameters such as electrode distance and
gas type (oxygen, argon and air) at voltages of 9.56 kV- 13.53 kV over treatment
durations of 0.5-2.5 minutes.
The study assessed ACP’s efficacy against chlorine-resistant and non-chlorineresistant bacteria, examining direct ACP treatment and effects after 24 h storage
post-treatment. Bacterial suspensions at initial concentrations of 1 x 107 CFU/mL
were exposed to varying treatment conditions, with bacterial inactivation
analysed via colony counts and statistical analyses (two-way ANOVA with
Tukey’s post-hoc). The results indicated significant log reductions in bacterial
populations, with ACP achieving up to 4-log reductions, particularly against
chlorine-resistant, Gram-negative bacteria. Among the gases tested, argon
plasma had the highest bacterial inactivation rates, outperforming oxygen and air
plasma, particularly against chlorine–resistant bacteria.
Environmental water samples treated with ACP showed 90-100% bacterial
inactivation, corresponding to log reductions of 3-5 logs, consistent across both
direct and 24 h storage post-treatment samples. Argon and oxygen plasma
showed high efficacy, with oxygen plasma having the highest inactivation in the
uMhlanga Lagoon sample. The sustained antibacterial effect of ACP after 24 h
storage post-treatment was attributed to its disruption of bacterial cellular
functions, effectively inhibiting regrowth and ensuring long-term water safety. These findings confirm the potential of ACP as a highly effective and adaptable
disinfection technology for water purification, particularly in targeting bacteria with
carrying resistance profiles. While this study highlights the efficacy of ACP in
inactivating pathogenic bacteria, further research is needed to ensure the safety
of treated water for human consumption and to evaluate its effectiveness in
removing chemical contaminants. This study demonstrates that ACP is a highly
effective disinfection technology for water treatment, with consistent success in
inactivating a wide range of pathogenic bacteria.
Performance analysis of a reverse electrodialysis stack for electricity generation in KZN, SA
No full textThis dissertation is submitted in the fulfilment of the requirements for the degree of Master of Engineering in Chemical Engineering, Durban University of Technology, Durban, South Africa, 2024.The Earth is now 1.1 ℃ warmer than in the 19th century, with a 50% surge in atmospheric CO2
levels. Climate scientists stress the importance of limiting global warming to 1.5 ℃ by 2100,
emphasizing the need for immediate action. However, without intervention, projections
suggest a potential temperature rise exceeding 2 ℃ or even reaching 2.4 ℃ by the end of this
century. Failure to address this issue could result in catastrophic consequences, including
severe heatwaves, widespread displacement due to rising sea levels, and irreversible damage
to plant and animal species. The urgency to curb greenhouse gas emissions and mitigate the
impacts of climate change is paramount to safeguarding the future of the planet.
In 2015, leaders of different countries made a crucial global initiative in Paris, France—the
Paris Agreement. This agreement addresses urgent climate challenges, recognizing that failure
to tackle climate change could lead to catastrophic consequences, from severe heatwaves to the
irreversible loss of biodiversity. By committing to curb greenhouse gas emissions, the Paris
Agreement provides a vital framework for safeguarding the planet's future and fostering
international collaboration in the face of climate adversity.
South Africa faces a critical energy challenge marked by frequent load shedding and heavy
reliance on coal-based electricity generation. The energy sector plays a pivotal role in the
nation's socio-economic development, and the persistent power shortages have significant
repercussions on industrial output, livelihoods, and environmental sustainability. This
precarious situation necessitates a shift towards sustainable and renewable energy sources. In
February 2020, South Africa released its Low Emission Development Strategy, with the goal
of achieving a net-zero carbon economy by 2050. This dynamic strategy provides flexibility
for South Africa to adapt its approach, considering emerging innovations and alternative energy
options. One promising avenue is the utilization of Reverse Electrodialysis (RED) technology,
which harnesses the salinity gradient between concentrated solutions usually seawater and less
concentrated solution usually river water to generate electricity. Despite its potential, the
integration of RED technology into South Africa's energy landscape remains underexplored
and underutilized.
This research aims to investigate the parameters that affects power generation in a RED stack
using local waters. The impact of electrode rinse solution on the stack remains a scarcely
explored area. Despite the significant advancements in RED technology, there is a notable gap
in understanding the effect of electrode rinse solutions on RED stack performance. The study was divided into three parts. The first part of the study involved comparing the effects of
different electrode rinse solutions (ERS) on open-circuit voltage (OCV), power density, and
internal resistance. The solutions tested included Potassium Chloride (KCl), Sodium Chloride
(NaCl), Sodium Sulphate (Na2SO4), and a mixture of Potassium Ferricyanide anhydride,
Potassium Ferrocyanide trihydrate, and Sodium Chloride [K3Fe(CN)6, K4Fe(CN)6, and NaCl].
The comparison was based on Open Circuit Voltage (OCV), Voltage Under Load (VUL),
internal resistance, and power density. Variables investigated included the flow rate of the rinse
solution, concentration, and composition. The flow rate of the ERS was varied from 9.15 to
18.3 L/h, and the concentration was varied from 5 to 30 g/L. But for the mixture, four of the
most commonly used molar concentrations in literature were chosen. The experiments were
conducted at room temperature (25 ℃ ± 0.5). The feed comprised of synthesized sodium
chloride solutions flowing at a constant rate of 900 mL/min, with concentrations of 0.4 g/L for
the less concentrated solution and 38 g/L for the more concentrated solution. The results
indicated that the ERS significantly influences the power generation of the stack. The mixture
demonstrated the best performance in terms of OCV, VUL, internal resistance, and power
density. This superior performance can be attributed to the presence of redox species in the
mixture. The highest recorded values for OCV, VUL, and power density were 4.354 V, 0.966
V, and 8.964 W/m2
, respectively, and these were exclusively measured when using the mixture
as an ERS. When comparing the highest power density measurement for the mixture to the
highest power density measurement for KCl solution, a notable difference of 73% was
observed. Additionally, the lowest internal resistance recorded was 14.26 Ω, and it occurred
with the mixture as the ERS.
The second part of the study involved using seawater and various river water samples as feed
solutions, with manipulated variables including the temperature and flow rate of the feed. The
temperature ranged from 25 to 40 ℃, and the flow rate varied between 900 and 1550 mL/min.
The ERS was circulated at a constant flow rate of 153 mL/min. Results indicated that
temperature had a more pronounced effect on power generation compared to flow rate.
Notably, the highest increase in power density was 60.0% from a temperature of 25 to 40 ℃.
On the other hand, the highest increase in power density was 31.3% from a flow rate of 900 to
1550 mL/min. Internal resistance was significantly influenced by temperature, with the lowest
values consistently observed at the highest temperatures and flow rates.
In the final part of the study, a software tool, Design Expert, was employed to identify the
optimum point for the system. uMkomaas river water sample was utilized for this analysis. Data of the runs was feed to the Design Expert software under historical data. Low coded
factors, which is -1, were 900 and 25 for flow rate and temperature, respectively. High coded
factors, which is 1, were 1550 and 40 for flow rate and temperature, respectively. The responses
of the system were OCV and VUL. ANOVA was used to analyze the system’s historical data
and optimize the process. The order of optimization was Quadratic. The adjusted R2
for OCV
and VUL were 0.8048 and 0.6484, respectively. The surface response was analyzed. The
optimum conditions achieved a desirability of 92.7%. Four runs were conducted as
confirmation.
The impact of COVID-19 pandemic on supply chain performance : a case of an earth-moving equipment manufacturer
No full textSubmitted in fulfilment of the requirements of the degree of Master of Engineering, Durban University of Technology, Durban, South Africa, 2024.The COVID-19 pandemic impacted the supply chain performance of an earth-moving
equipment manufacturer in KwaZulu-Natal, South Africa. The pandemic damaged the
company's supply chain, causing material shortages and production problems which
made it difficult to satisfy customer demand. This research aims to maximize the supply
chain of an earth-moving equipment manufacturer in South Africa through the
identification and addressing of supply chain blockages that were created by the COVID19 pandemic. The study seeks to characterise the defining elements of supply chain,
identify factors affecting performance, apply value stream mapping for efficiency, and
develop a framework model for supply chain optimization. Ultimately, the study seeks to
address gaps in comprehending the long-term effects of the pandemic on earth-moving
equipment manufacturers' supply chains and propose strategies to build resilience
against future disruption. Quantitative approach was used to analyse forecast data
against actual deliveries to control productivity and delivery performance. Six Sigma,
cause-and-effect diagrams, and time studies methods were used to identify inefficiencies.
Supply change elements were characterised using Gemba walks and process flow
mapping, which provided direct observations of operations and visualizing interconnected
processes. Pareto analysis, cause-effect diagrams, value stream mapping, and time
studies were used for identifying supply chain performance issues, improving supply
chain efficiency, and recognizing waste and production blockages. Qualitative
observations and quantitative measurements of production processes were used for data
collection. The methodology provided a comprehensive insight into the supply chain
problems and areas to apply targeted improvements to increase efficiency and customer
satisfaction. Findings highlighted the importance of developing strategies including
diversification among suppliers, workforce development, logistics optimization, adoption
of digital technologies, and improvement in demand planning. The study also identified
that adaptable production scheduling increased the company's capability to meet
customer demands. The influencing factors on supply chain performance were found to
be inventory management problems, supplier reliability, workforce issues, and
technological adoption, requiring a collaborative approach for long-term supply chain
resilience. The study concluded that a comprehensive approach to technological adoption, workforce development, supplier collaboration, and flexible operations is
fundamental for maximizing performance within the supply chain and building resilience
against future disruptions.
Physical activity and health during the SARS-COV-2 pandemic : the effectiveness of an online physical activity intervention
No full textThesis submitted in fulfilment of the requirements for the Doctor of Philosophy in Health Sciences
at the Durban University of Technology, Durban, South Africa, 2025.Regular physical activity (PA) is known to have several benefits in terms of physical and
mental wellbeing. Researchers in the field of public health have investigated these benefits for
several years with the general consensus that regular PA has immense potential to maintain
health, prevent the development of non-communicable diseases and to contribute toward
overall well-being. The last years have seen the emergence of online PA programmes as an
option for increasing PA and this continues to increase with the evolution of technology and
development of resources. The overall concept of online PA has been shown to provide PA
opportunities for individuals who may not be able to, or may not desire to, access traditional
PA establishments such as gyms, sports centres and clubs, among many others. It also provides
an additional option for the accumulation of PA.
In March 2020, South Africa became integrated in the fight against the SARS-CoV-2
pandemic. The pandemic was an unpredictable time for the global population, with this highly
contagious virus creating a state of disaster around the world. SARS-CoV-2, otherwise known
as COVID-19, left the health sector in a state of turmoil. The high mortality and hospitalisation
rates associated with the virus rapidly depleted healthcare resources. Government officials
around the world were forced to impose lockdown restrictions in an attempt to control the
spread of the virus, decrease mortality and hospitalisation rates and conserve healthcare
resources. The lockdown restrictions were implemented according to WHO guidelines and
allowed for individuals to move around only when considered essential. These restrictions may
have assisted in managing the pandemic, however, the isolation created an underlying concern
with regards to PA, particularly as a result of the closure of most public spaces, including sport
establishments. Consequently, this necessitated a dire need for online PA programmes to
become a more focused mechanism for promoting the accumulation of PA and minimising the
impact of the reduced conventional PA opportunities, during the pandemic.
Aims & Objectives
This study aims to interrogate existing online PA programmes and their effects on physical and
mental outcome measures and to evaluate the effectiveness of an online physical activity
intervention programme during the SARS-CoV-2 pandemic. Objective 1
To conduct a PROSPERO registered systematic review and meta-analysis pertaining to online
PA interventions and its effectiveness in healthy individuals with regard to physical and mental
outcome measures.
Objective 2
To conduct a re-focused analysis of and report on the South African data from an international
online population-based survey.
Objective 3
To lead the South African cohort of a multicentred, two-armed, randomised-controlled trial and
specifically re-analyse and report on the South African specific data obtained from this trial.
Objective 4
To provide guidelines and recommendations for future online PA programmes based on the
research findings.
Methods
Systematic Review and Meta-analysis
A literature search was conducted on PubMed, Cochrane and Google Scholar. RCTs that were
4-weeks or longer in duration which investigated the effectiveness of online exercise (OE)
versus no exercise (NEX) controls or face-to-face (FFE) exercise in healthy adults were
included. A quality rating of each study included was conducted using the PEDro scale.
Relevant data from each study were then extracted for a meta-analysis. The effect sizes were
pooled using robust variance estimation.
South African Survey
A focused analysis of the SA statistics from the global Activity and health during the SARS-
CoV-2 Pandemic (ASAP) study was conducted. This descriptive study consisted of an online
cross-sectional questionnaire that was administered from 3 April 2020 to 9 May 2020. The
questionnaire used the Nordic Physical Activity Questionnaire-short (NPAQ-short), and a five-
point Likert scale to quantify changes in PA levels and WHO PA guideline compliance
respectively. The data were analysed according to age and gender categories. Logistic
regression was performed to identify significant themes emerging from the data. South African Analysis of a Global Randomised Controlled Trial
A multicentred RCT was conducted to assess the effects of an 8-week trial (4-weeks of active
intervention and 4-weeks of recorded sessions), with live-streaming exercise sessions provided
by professionals in the field of sports and exercise medicine. Measures of physical and mental
wellbeing were evaluated by means of weekly digital surveys. These measures included the
NPAQ-short for PA levels, Generalised Anxiety Disorder Scale-7 (GAD-7) for anxiety, WHO-
5 for mental wellbeing, Medical Outcome Study Sleep Scale (MOS sleep scale) for sleep,
Chronic Pain Grade Scale (CPGS) for pain and disability and Self-Concordance Scale (SKK)
for exercise motivation. The thesis includes a focused analysis of SA data from the global
study, to assess SA-specific changes in PA levels and exercise motivation during the initial 4
weeks (live-streaming sessions) of the intervention.
Guidelines for Future Online Physical Activity Interventions
Specific recommendations for future online PA programs, have been formulated based on the
findings of the various parts of this thesis.
Findings
Systematic Review and Meta-analysis
A total of 18 moderate to high methodological quality studies (PEDro scale) were included.
OE improved more than NEX in measures of strength (Standard Mean Difference (SMD)
=0.61), balance (SMD=0.52), endurance (SMD=0.85), PA (SMD=0.46), depression
(SMD=1.08), mood/emotion (SMD=0.47), mental wellbeing (SMD=0.79), and self-efficacy
(SMD=1.1). OE was less effective than FFE in all outcomes. GRADE classification revealed
a low-moderate evidence certainty.
South African Survey
The analysis of 456 adult participants questionnaire responses revealed that, moderate (MPA)
and vigorous (VPA) PA were reported to have reduced by 53.5% and 58%, respectively. The
SA reductions in PA were higher than the those noted in the overall global study where
reductions were reported as 41% in MPA and 42.2% in VPA. Approximately one third (30%)
of the SA sample recorded a reduction in WHO PA guideline compliance during lockdown
restrictions. South African Analysis of a Global Randomised Controlled Trial
The analysis of the data from 105 participants (65 intervention; 40 control), that completed the
initial 4-weeks active phase of the RCT showed a reduction in MPA in both the intervention
group (IG) and control group (CG) of 32.6% and 16.1% respectively. VPA also reduced in the
IG (42.1%), however, increased in the CG. Scores for exercise motivation increased by 13.1%
and 16.9% IG and CG, respectively.
Conclusion
The systematic review and meta-analysis conducted in this thesis, indicates that there is a
moderate level of evidence to support the use of online PA, when attempting to improve
markers of physical and mental health. The SARS-CoV-2 pandemic, placed further emphasis
on the need for effective online PA protocols, that allow for an increase in PA engagement as
shown by the results of the survey analysed in this thesis. This need is exaggerated in instances
when individuals are unable to access face-to-face PA facilities, especially since literature
analysis indicated there is merit to online PA programs. However, the RCT analysis revealed
that, in order for specific populations like South Africans, to benefit fully from such programs,
there needs to be a level of customisation in the program planning. This customisation should
carefully consider the context, strengths and limitations that are population specific.
Notwithstanding this, there is great potential in the field of online PA intervention research,
particularly considering that existing online PA interventions have been reported as effective
in not only improving PA levels but also towards supporting overall wellbeing. Future online
PA interventions should therefore consider the identified key focus aspects during the
development and implementation, to maximise uptake outcomes and overall impact of such
programmes.
Metabolomic profiling, computational and experimental validation of sunflower seeds as therapeutics against type-2diabetes mellitus
No full textSubmitted in fulfilment for the Degree of Master of Applied Science in Biotechnology, Durban University of Technology, Durban, South Africa, 2025.Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by impaired
glucose metabolism due to insufficient insulin secretion or insulin resistance. This global health
crisis is projected to affect an estimated 7079 individuals per 100,000 by 2030. While
medications like metformin are effective, accessibility and affordability are issues consistent
with low-income populations alongside potential side effects like hypoglycaemia, nausea and
gastrointestinal issues that have limited their use in clinical practice. More importantly,
uncontrolled T2DM can lead to serious complications like retinopathy, nephropathy,
neuropathy, and delayed wound healing. Therefore, this prompts the search for alternative
management options that are safer, easily accessible, affordable and with minimal side effects.
Plants and their products are becoming increasingly important due to their relative ease of
accessibility, affordability and potential health benefits. Sunflower seed, a popular dietary
snack, has rich nutritional profile and has found significant health benefits as an antiinflammatory, antioxidant, anticancer, antimicrobial, and antidiabetic agent. While the
antidiabetic potential of sunflower seeds has been explored, there remains a lack of
understanding on its mechanism of action. This study addressed this knowledge gap by
establishing the comprehensive metabolite profiles and investigating the antidiabetic efficacy
of sunflower seed extracts through a two-pronged approach: targeted enzyme inhibition and
network pharmacology analyses complemented with experimental validation in vitro.
Metabolomic profiling of six cultivars of sunflower seeds commonly consumed in South
Africa, namely, AGSUN 8251, 5270, 5101 CLP, 5103 CLP, 5106 CLP and 5108 CLP was
performed using Liquid chromatography – mass spectrometry (LC-MS) and Gas
chromatography – mass spectrometry (GC-MS) techniques. A total of 94 metabolites were
identified, with LC-MS analysis revealing 44 phenolic compounds across the six cultivars with
a minor variance of 39.7%, while GC-MS analysis revealed the presence of volatile compounds
such as organic acids, alkanes, alcohols, terpenes, heterocyclic compounds and hydrocarbons
in all the cultivars in similar abundance. Noteworthily, 84 of the 94 metabolites profiled passed
Lipinski’s rule of five and were selected for further analysis.
For the enzyme inhibition study, molecular docking analysis was initially used to screen the
profiled metabolites against the key enzymes [α-amylase (AAMY), α-glucosidase (AGLU),
aldose reductase (AR), sorbitol dehydrogenase (SDH), dipeptidyl peptidase 4 (DPP-4) and protein tyrosine phosphatase 1B (PTP1B)] implicated in T2DM pathogenesis and its secondary
complications. The top-ranked metabolites against each enzyme were further subjected to
molecular dynamics (MD) simulation to identify putative leads with the strongest binding
affinity, and unperturbed structural integrity through evaluation of their stability, compactness
and intermolecular interactions. This aspect of the study identified sonchuside I (SON I) -
AAMY (–47.26 kcal/mol), sacranoside A (SAC A) - α-glucosidase (–40.10 kcal/mol),
pelatoside A (PLT) - AR (–58.84 kcal/mol), sacranoside A (SAC A) - SDH (–48.03 kcal/mol),
4α,6S,7α)-6α-[6-O-(4-Hydroxybenzoyl)-β-D-glucopyranosyloxy]-7βmethyloctahydrocyclopenta[c]pyran-1-one) (PYR) -DPP-4 (–37.93 kcal/mol) and chlorogenic
acid (CGA)-PTP1B (–24.32 kcal/mol) as potential lead inhibitors of the respective enzyme
relative to their respective reference standards. This was further supported by their improved
thermodynamic properties and favourable post-dynamic simulation parameters such as
improved stability and compactness of their resulting complexes. These observations are
suggestive of multiple mechanisms by which sunflower seed may exert its antidiabetic effects
such as anti-hyperglycaemia (α-amylase and α-glucosidase), prevention and management of
diabetic complications (AR and SDH), increasing insulin signalling (DPP-4) and sensitivity
(PTP1B) by the respective putative leads.
For network pharmacology analysis, the filtered sunflower seed metabolites were used to create
a gene-compound library that was subsequently used to identify genes commonly associated
with both the metabolites and T2DM. Thereafter, Kyoto Encyclopaedia of Genes and Genomes
(KEGG) pathway enrichment analysis was performed to identify the most significantly
enriched pathways with key target genes for molecular docking and MD simulations to identify
lead metabolites. Finally, the antidiabetic activity of sunflower seed extracts and the findings
from the network pharmacology analysis were validated using insulin-resistant HepG2 cells
where glucose consumption assay and gene expression analysis were performed. The network
pharmacology analysis revealed a total of 87 genes common to sunflower seeds metabolites
and T2DM, whereas KEGG enrichment analysis highlighted 35 signalling pathways
potentially influenced by the metabolites. Of these, the Peroxisome proliferator-activated
receptor (PPAR) signalling pathway and its hub receptors, Matrix metalloproteinase-1(MMPI)
and peroxisome proliferator-activated receptor alpha (PPAR) were selected as the most
significant. These receptors interacted mostly with the identified metabolites, with CGA (–
43.74 kcal/mol), GPA (–41.62 kcal/mol), and CFG (–45.36 kcal/mol) having lower binding
free energy than both reference standards, rosiglitazone (ROS) and metformin (MET) against MMP1 after 100 000 ps MD simulation. In contrast, ROS (–46.98 kcal/mol) had better affinity
against PPARA compared to the top-hits derived from sunflower seeds. However, against both
genes, the top-hits had significant thermodynamic stability, flexibility, and compactness, which
are attributable to their bond interactions and molecular orbital properties. These findings are
suggestive of the essential role of the top-hits in the antidiabetic potential of sunflower seeds
through activation of the PPAR signalling pathway and most especially MMP1. In this regard,
the modulation of MMP1 and PPARA genes by the identified metabolites of sunflower seeds
may enhance insulin sensitivity and glucose homeostasis in the management of T2DM. Finally,
the in vitro validation using insulin-resistant HepG2 cells revealed cultivar-specific effects on
cell viability, with each cultivar having a unique optimal concentration. Overall, all cultivars
demonstrated the ability to stimulate glucose consumption, suggesting their potential
antihyperglycemic activity. Among the cultivars, AGSUN 5103 CLP (14.4 mmol/L), 8251
(14.6 mmol/L), and 5101 CLP (13.7 mmol/L) exhibited the most pronounced glucose lowering
action compared to the untreated cells (23.3 mmol/L) after 24 h, highlighting their promising
antidiabetic effects. These three cultivars also modulate the PPAR signalling pathway, as
evidenced by the upregulation of MMP1 and PPARA expression. Specifically, AGSUN 5101
CLP emerged as a particularly promising candidate based on its superior glucose lowering
potential and higher fold increase expression of MMP1 (1.88) and PPARA (4.59) compared to
the effect observed with the untreated cells (1.00).
In conclusion, this study provides compelling evidence for the antidiabetic potential of
sunflower seeds. The observed effects on enzyme inhibition, activation of the PPAR signalling
pathway, and stimulation of glucose uptake in HepG2 cells suggest a multifaceted approach by
the seeds in regulating blood sugar levels. The identification of cultivar-specific effects and
promising lead compounds warrants further investigation to explore the therapeutic potential
of sunflower seeds in managing T2DM.
The perceived role and representation of women on television : a study of South African soap operas
No full textSubmitted in fulfillment of the requirements of the degree of Doctor of Philosophy in Public Relations and Communication, Durban University of Technology, Durban, South Africa, 2025.This study focuses on media representation of women through selected South African
television soap operas. The problem at the crux of the study is that women encounter
prejudiced depictions from different media, resulting in women being perceived as
inferior and of less status compared to men. This subject has a significant effect on
gender relations in society, as media representations of gender shape gender identity.
The study examines the roles and representation of women on television soap operas
to discover how these depictions reflect, reinforce or contest societal gender norms.
Soap operas are a prominent genre on television, and they have been historically
linked to female audiences and are frequently regarded as a crucial arena for the
negotiation of gender identities. The research utilises a predominantly qualitative
mixed-methods approach, gathering data through focus group discussions, semistructured interviews, and questionnaires. The research integrated textual analysis of
selected soap operas with audience feedback to evaluate the positioning of women
within narrative frameworks, character roles, and thematic progressions.
Results indicate an intricate interaction between progressive and stereotyped
portrayals. Some female characters are shown as assertive and autonomous, while
others are restricted to traditional roles that highlight domesticity, emotionality, and
reliance on male counterparts. The research emphasises the cultural importance of
soap operas in influencing public views on gender and illustrates the medium's
capacity to reinforce or contest prevailing gender beliefs. The study’s boarder
significance is that, women’s fair representation can play a role in tackling social
injustices suffered by women, such as gender-based violence (GBV) and femicide.
Media do not directly cause femicide or any other acts of injustice directed to women,
however, their coverage and depiction can influence public perception and attitudes
towards injustice, potentially normalising and trivialising it.
Optimization of photocatalytic degradation of wastewater using oxide and non-oxide photocatalysts
No full textA dissertation submitted in fulfillment of the academic requirement for the degree of Master of Engineering: Chemical Engineering, Durban University of Technology, Durban, South Africa, 2025.Wastewater treatment is a global concern, especially in developing countries with
limited access to safe and clean facilities, resulting in individuals practicing unsafe
and unsustainable human practices. This poses challenges for South African
wastewater treatment plants (WWTPs) due to the aging infrastructures and the use
of conventional technologies. Also, recent population growth, urbanization, and
industrial activities have given rise to contaminating water resources with
recalcitrant organic micropollutants (OMPs). Organic micropollutants cause
severe environmental pollution, imbalanced ecosystems (aquatic life), human
health risks, and oxygen depletion due to accelerated chemical oxygen
demand (COD). Apart from the detrimental effects of wastewater on human health
and the ecosystem, the United Nations (UN) sustainability development goal of
obtaining clean water and sanitation (SDG #6) by 2030 is continuously threatened.
Therefore, treating wastewater for reuse in the environment with good quality comes
in handy.
Against this background, photocatalysis, such as the advanced oxidation process
(AOP), is reported as a promising, eco-friendly, and cost-effective technology for
degrading organic contaminants (COD) into harmless compounds. However, the
TiO2-based photocatalytic process has setbacks, such as recoverability and
treatability efficiency, limiting its industrial application. Therefore, this study explored
oxide and non-oxide photocatalysts as alternatives to TiO2-based photocatalytic
processes for a local South African wastewater treatment. The photocatalysts
considered were Titanium dioxide (TiO2), Iron (III) oxide (Fe2O3), Zinc Sulphide
(ZnS), and Copper Sulphide (CuS). Their applicability was conducted
experimentally by evaluating and optimizing the performance of oxide (TiO2, Fe2O3)
and non-oxide (ZnS, CuS) photocatalysts under UV, UV-visible, and natural sunlight
irradiation.
The One-Factor-at-a-Time (OFAT) approach was used on the photocatalytic system
to identify the relationship between the variables that influence the photocatalytic
degradation treatment of municipal wastewater. The water quality parameters
considered were pH, turbidity (NTU), colour (Pt. Co), and COD (mg/L). By
employing the oxides and non-oxides under a constant UV irradiation light source
vi
and OFAT approach, the catalyst load (0.5-2.5 g/L), mixing speed (30-150 rpm),
and exposure time (10-60 minutes) were investigated. Among the photocatalysts,
CuS displayed the best results overall for above 50% COD removal efficiency, whilst
ZnS was also efficient in removing above 50% turbidity and colour at a catalyst load
of 1.5 g/L, mixing speed of 90 rpm, and UV exposure time of 45 minutes. It was
established that CuS was the cheapest at R2.01/1.5g as compared to TiO2 at
R32.47/1.5g.
Subsequently, the photocatalysts were investigated using three different light
sources: UV, UV-visible, and sunlight irradiation. UV-visible was the most
favourable at a catalyst load of 1.5 g/L, mixing speed of 90 rpm, and irradiation time
of 60 minutes. Thus, the high light intensity of UV-visible, 191,000 Lux, enhanced
the photocatalytic performance of the four photocatalysts under this study, with the
optimum COD removal values at 72.25%, 70.87%, 70.20%, and 46.66% for Fe2O3,
ZnS, CuS, and TiO2 respectively.
Furthermore, response predictive models were developed as a function of the input
factors of the photocatalytic system for the treatment of municipal wastewater. This
was done utilizing the response surface methodology (RSM) via the Box Behnken
design (BBD) with the best-performing catalyst (CuS) and the best light source (UV visible), at the optimal conditions of catalyst load of 2 g/L CuS, a mixing speed of
120 rpm, and an exposure time of 30 minutes with treatability desirability of 96%.
The selected optimal condition was then validated experimentally, and the results
obtained were agreeable with the model-predicted values at 95% confidence levels.
Moreover, a comparative study with CuS and TiO2 was evaluated with synthetic
wastewater (SW) and raw wastewater (RW) at the optimal conditions. The results
by CuS demonstrated above 55% COD, turbidity, and colour removal from both the
SW and RW compared to the TiO2, which obtained below 35% removal from both
SW and RW. Therefore, under the conditions investigated in this study, CuS was
found to be the most cost-effective and viable photocatalyst alternative to TiO2 for
wastewater treatment. However, the techno-economic and life cycle assessment
must be explored to encourage the prospects of the CuS in the water settings
The impact of COVID-19 on the financial performance of insurance companies in South Africa
No full textThe research aims to examine the influence of the Covid-19 pandemic on the
financial performance of insurance companies in South Africa. The research sample
comprises 37 insurance companies that are duly registered with the Financial
Sector Conduct Authority (FSCA). The research used a descriptive analytical
technique, focusing on quantitative and numerical data from annual financial
reports published by insurance companies. The data was used to assess financial
performance indicators over a time period of six consecutive years (2017–2022). The
study indicated that Covid-19 had diverse impact on the financial performance of
insurance companies. The study demonstrates a positive and statistically significant
correlation between COVID-19 and ROA. This conclusion indicates that, despite the
obstacles posed by the pandemic, several insurance companies adeptly managed
their assets to maintain profitability. Conversely, the findings demonstrate a negative
correlation between COVID-19 and ROE, underscoring the strain on equity returns