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Enhanced bioethanol production from potato peel waste: nano-assisted detoxification, co-fermentation with Saccharomyces cerevisiae and Pichia stipitis, and process scale-up.
(2026) Adebule, Adeniyi Philip.; Gueguim Kana, Evariste Bosco.; Sanusi, Adeyemi Isaac.
The environmental and climate impacts associated with fossil fuel consumption have led to the search for sustainable alternatives, including renewable, bio-based fuels and products from lignocellulosic biomasses. Lignocellulosic biomass, particularly agro-industrial residues like potato peels, has emerged as a promising feedstock for second-generation bioethanol production. However, the microbial conversion of lignocellulosic biomass into large-scale bioethanol production is challenged by several factors, including the formation of inhibitory compounds during biomass pretreatment, inefficient utilization of mixed sugars and low yield. Therefore, this study explored the co-fermentation of S. cerevisiae and P. stipitis, integrated with nanoparticle-based detoxification of inhibitory compounds, process kinetics and scale-up to enhance bioethanol production efficiency from potato peel waste (PPW) hydrolysates.
In this study, the pretreated PPW hydrolysate was subjected to a Fe3O4 nanoparticle-assisted detoxification process modelling and optimization using Response Surface Methodology (RSM) for the simultaneous removal of five key fermentation inhibitors: furfural, 5-hydroxymethylfurfural (HMF), phenol, acetic acid, and formaldehyde. An artificial neural network (ANN) was employed to model the removal of inhibitors and identify key process variables. The RSM and ANN strategies were complemented with sensitivity analysis, adsorption-desorption kinetics, and thermodynamic studies to further elucidate the underlying detoxification mechanisms. The detoxified PPW hydrolysate was employed for bioethanol production, comparatively using simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) strategies to establish the most efficient fermentation strategy. This was followed by substrate utilization, growth and bioethanol production kinetic studies. Thereafter, the simultaneous saccharification and co-fermentation (SSCF) process with S. cerevisiae and P. stipitis was modelled and optimized using the RSM to maximize sugar bioconversion for improved bioethanol production. The optimised SSCF was evaluated for preliminary scale-up with specific consideration given to reactor geometry, rheological behaviour, and hydrodynamic parameters.
First, the pretreated PPW hydrolysate was subjected to optimized nanoparticle-assisted detoxification conditions, resulting in significant removal efficiencies for furfural (1.65-fold), 5-hydroxymethylfurfural (1.21-fold), phenol (1.95-fold), acetic acid (3.25-fold), and formaldehyde (1.55-fold), without sugar loss. Sensitivity analysis revealed that pH and initial inhibitor concentration were the critical influencing factors. The characteristic profile and adsorption mechanism of Fe3O4 nanoparticles (NPs) were elucidated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV spectrophotometry, X-ray diffraction (XRD), point of zero charge (PZC), and the Brunauer–Emmett–Teller (BET), suggesting surface adsorption and complexation as the primary detoxification mechanisms. The adsorption mechanisms were further substantiated through pseudo-first-order, pseudo-second-order, intra-particle diffusion, Elovich, Langmuir, Freundlich, Temkin and thermodynamic studies. The finding indicated chemisorptive interactions between Fe3O4 nanoparticles and inhibitors. Phenol and HMF adsorption best fitted the Langmuir model (R² = 0.997 and 0.966), respectively, suggesting monolayer adsorption on uniform surfaces. Acetic acid and formaldehyde followed the Freundlich model (R² = 0.985 and 0.980), respectively, indicating heterogeneous surface adsorption, while furfural fitted the Temkin model (R² = 0.970), reflecting moderate, energy-distributed adsorption. The Fe3O4 nanoadsorbent demonstrated a multi-site adsorption mechanism involving hydrogen bonding, π–π interactions, and electrostatic forces, consistent with chemisorption. Hence, the optimally detoxified hydrolysate was employed for bioethanol production.
The SSF bioethanol production strategies demonstrated improved performance over SHF, achieving a saccharification efficiency of 88.95% and a bioethanol yield of 26 g/L. Consequently, the logistic function, modified Gompertz, Luedeking-Piret, and modified Luedeking-Piret performed on the SSF process further revealed improved metabolic performance that was predominantly growth-associated (α = 3.515 g P/g X and γ = 6.543 g S/g X), with a low cell maintenance coefficient (δ) value (0.0019 g S/g X h). This data indicated that S. cerevisiae relies strongly on efficient substrate availability and processability for optimal ethanol biosynthesis under detoxified conditions. However, the inefficient bioconversion of fermentable sugars in the detoxified hydrolysate necessitated the adoption of a co-fermentation strategy to enable simultaneous utilization of glucose and xylose present in the hydrolysate. For the SSCF process optimization, the optimal co-fermentation conditions were determined to be a zero-hour co-inoculation time, an inoculation ratio of 1:4 (S. cerevisiae to P. stipitis), and a 10% solid loading. Under these conditions, improved bioethanol concentration of 48.7 g/L, maximum specific growth rate (μmax) (0.752 h-1), bioethanol productivity (4.06 g/L/h), yield (0.505 g/g) and fermentation efficiency of 99% were achieved.
Scaling the SSCF process from 1 L to 10 L while maintaining constant non-gassed power (0.012 W), impeller tip speed (0.35 m/s), temperature (35°C), and pH 5.78, ensured comparable bioethanol production efficiencies with productivities of 3.653 and 3.635 g/L/h and bioethanol concentrations of 43.68 g/L at 1 L and 10 L, respectively. A desirable pumping capacity (VP = 3.9 ˟ 10-4 m3/s) and a 10-fold reduction in Power-to-Volume ratio (P/VL= 1.2 W/m3) characterised the 10L scale, indicating a significant improvement in energy efficiency at pilot scale. The logistic model (R2 >0.938) yielded maximum specific growth rate (μmax) of 0.436 h−1 (1 L) and 0.415 h−1 (10 L), and maximum biomass concentration (Xmax) of 16.40 g/L (1 L) and 16.88 g/L (10 L). The modified Gompertz model (R2 >0.99) showed comparable maximum potential bioethanol concentration [Pm] (44.37 g/L for 1 L; 44.09 g/L for 10 L), maximum bioethanol production rate [rp,m] (6.68 g/L/h for 1 L; 6.63 g/L/h for 10 L), and lag time [tL] (2.94 h for 1 L; 2.69 h for 10 L). Interestingly, growth-associated product (α, 4.744 g P/g X) and substrate utilization (γ, 6.611 g S/g X) coefficients further aligned with experimental data (R2 >0.90), confirming model fitness across scales.
This study presents a novel integrated strategy that combines dual optimisation of Fe3O4 nanoparticle-assisted detoxification of pretreated potato peel waste (PPW) hydrolysate and co-fermentation of detoxified PPW hydrolysate using S. cerevisiae and P. stipitis to enhance bioethanol production. The findings further demonstrated the efficiency and underlying mechanisms of Fe3O4 nanoparticles in improving the processability of hydrolysate, substrate affinity, substrate uptake as well as growth kinetics of S. cerevisiae and P. stipitis, thereby enhancing bioethanol productivity, yield and subsequent pilot scale-up. Underscoring the suitability of the developed process design for industrial implementation towards sustainable large-scale bioethanol production from agricultural residues.
Exploring the experiences of non-specialist mathematics teachers in implementing the curriculum in the intermediate phase at Tongaat schools.
(2023) Rambali, Risha.; Msiza, Vusi Jan.
The experiences of non-specialist teachers in relation to their subject and pedagogical knowledge remains under-researched both nationally and internationally. Scholarship reports that teachers’ subject matter and pedagogical knowledge contribute significantly to their teacher experience. However, existing literature on the experiences of non-specialist teachers suggests that there is a disconnect between their knowledge and their practice, especially in the cases where they are teaching core subjects like mathematics. This study aimed to explore the experiences of non-specialist mathematics teachers in implementing the curriculum in the intermediate phase at schools in Tongaat, KwaZulu-Natal. To understand the participants’ experiences, I used Shulman’s (1987) model of teacher knowledge as the theoretical framework. In the study I adopted a qualitative approach and a case study methodology with two data generation methods. Data from the participants (non-specialist mathematics teachers) was generated using a semi-structured interview consisting of an hour and thereafter followed by a one-hour lesson observation. In this study, purposive sampling was used to recruit the participants. The data was analysed through thematic analysis and I adopted both inductive and deductive ways of interpreting the data. The study found that most of the participants experienced challenges teaching mathematics as non-specialists. The reasons varied amongst the participants, although a common finding was a lack of both subject matter knowledge and pedagogical content knowledge. The study also found that most participants lacked passion, and this affected how they implemented the curriculum. Furthermore, another crucial finding was the lack of training and support afforded to the participants. The study has shown that all the above factors affect the quality of teaching and learning that takes place and therefore requires attention or intervention. The study, therefore, suggests that there is a need to understand the lived experiences of non-specialist teachers and to provide specialised training and support for them through workshops and mentorship. The study also suggests that the Department of Basic Education, should consider placing teachers in subjects that they specialised in.
Wrestling with underperformance pressures: narratives of six secondary school principals in Ilembe District.
(2023) Simelane, Ishmael Chibelihle; Bhengu, Thamsanqa Thulani
According to statistics, Grade 12 pass rate in the iLembe District has been progressively falling. Poor examinations result of Grade 12 learners in South Africa have caused major concerns in the educational and public sectors, particularly because there has been a growing awareness about issues of accountability for underperformance. Accountability meetings and criticism from commentators put principals under severe pressure, but some of them choose to skip meetings by taking lengthy sick leaves. These accountability sessions have caused a lot of stress on the principals involved, and in some instances, with lethal consequences. However, very little is known about the experiences of principals who experience pressure because of Grade 12 poor performance. This study has adopted a qualitative approached within an interpretive research paradigm and Narrative Inquiry was adopted as a research methodology. Field texts (data) were generated through narrative interviews and artefact inquiry. Narrative analysis and analysis of narratives—were completed. The study's focus was on six principals in the iLembe District. The study adopted three theories as its framework, and these are Identity Theory, Teacher Education and Diversity (ITTED), Context-Responsive Leadership (CRL)and Five Domains of Instructional Leadership Model. The findings suggested their leadership responses to underperformance in Grade 12 examinations was associated with the identities they had constructed about who they are. One of the major findings is that the performance of their school improved remarkably. From the strategies that these principals adopted, this study has generated a model I call a Multi-Stage Underperformance Pressure Coping Mechanism. This model is presented in Chapter Eight, and this model serves as one of the original contributions of this thesis.
The impact of independent smallholder irrigation on rural livelihoods in Msinga local municipality, KwaZulu-Natal Province, South Africa.
(2022) Dube, S'nethemba Valencia.; Caister , Karen Fern.
Independent irrigation is becoming more recognised in the research community and policy worldwide, apart from South Africa. It is associated with improving rural livelihoods by boosting household incomes and reducing poverty and food insecurities. South African literature sources on these irrigators do not present enough evidence to consider independent irrigation a reliable investment for irrigation development. In filling this gap, this research aimed to describe the livelihoods of independent irrigators and their contribution to rural livelihoods in Msinga Local Municipality. The study collected survey data from 101 irrigators selected using snowball sampling and four Focus Groups Discussions with participants chosen using a homogeneous purposive sample technique. The data were analysed using descriptive statistics, inferential statistics, the Probit model, and Thematic Content Analysis.
The study revealed that irrigator households in this Msinga had a weak asset base. Irrigators had restricted access to agricultural land, and most irrigators suffered severe limitations in irrigation water availability due to the unpredictability of their irrigation water source, hampered by periodic droughts in the research region. Msinga’s restricted land access meant crop production activities were limited to microscale production, and irrigation water shortcomings further hindered Msinga's independent irrigation land productivity. In Msinga, the study found that the crop production physical assets were limited to hand tools, implying that the physical assets were sufficient for independent irrigators’ current production spaces but needed to be improved to engage in crop production on a larger scale. Typical of the livelihoods of rural households in South Africa, Msinga households were ‘diversified’ because they typically contained multiple ways of obtaining income but centred around claiming against the state. Production of independent irrigated land was the second most important income source. Despite all its shortcomings, independent irrigation increased average annual household income by R8 156.90, 15.3% of the total average household income. Crops harvested at the irrigation plot were also consumed at home, forming part of the food expenditure and the money from sales was used to purchase other food items. Even though the contribution was "limited", independent irrigation improved Msinga irrigator households’ livelihoods through income generation and security of food. With relevant interventions in supporting these irrigators, independent irrigation could be an appropriate development path for rural households with proper interventions.
Citizens’ movement and COVID-19 in Senegal: textual analysis of songs concerning COVID-19 by Y’en a marre and other Senegalese musicians.
(2026) Nomvete, Asithandile.; De Meyer, Bernard Albert Marcel Sylvain.
Y’en a marre is a social movement that emerged in Senegal in 2011 in reaction to widespread social injustices, corruption, and the inefficacy of President Abdoulaye Wade’s administration. Founded by rappers Thiat and Kilifeu together with journalist Cheikh Fadel Barro, the movement initially responded to recurring power outages in Dakar caused by state mismanagement of the energy sector. It rapidly gained momentum, mobilizing youth against unemployment, inequality, and corruption through grassroots activism and politically engaged music. Their civic interventions contributed significantly to Wade’s electoral defeat in 2012, cementing Y’en a marre as a central actor in Senegalese civil society. The Covid-19 pandemic marked a new stage in the trajectory of this movement. Restrictions on gatherings limited its traditional forms of protest, but Y’en a marre and affiliated artists adapted by channelling their activism into public health awareness campaigns. They composed songs that promoted hygiene, mask-wearing, and social distancing, thereby making crucial information accessible to populations with varying levels of literacy. In this way, music became both a medium of resistance and an instrument of health communication. As Ndiaye and Rowley (2022) argue, Senegalese musicians collectively contributed to a form of “COVIDliteracy” through songs that addressed preventive measures, symptoms, and broader social meanings of the pandemic. Building on this scholarship, my dissertation focuses on the
contributions of Y’en a marre and other Senegalese artists in order to examine how music was mobilized during the crisis.
The study pursues two central lines of inquiry: first, how Y’en a marre positioned itself in relation to state power during the pandemic, shifting from an oppositional stance to a more collaborative role in public health efforts; and second, what discursive strategies were employed by these artists to transmit preventive messages and encourage civic responsibility. By engaging these questions, the research highlights the adaptability of Senegalese musicians and activists who transformed cultural practices into tools for collective resilience. This dissertation thus situates Y’en a marre within the broader landscape of Senegalese musical activism during Covid-19, illustrating how art and activism intersected with public health. More broadly, it contributes to discussions on the role of social movements in times of crisis, 6 showing how music can transcend its artistic function to become a form of civic engagement and a vehicle for social change.