Theses and dissertations (Engineering and Built Environment)

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Application of DMAIC technique to improve supply chain efficiency
(2025) Mthembu, Bongakonke Thandwayinkosi; Olanrewaju, Oludolapo Akanni; Mncwango, Bongumenzi T.
This study presents a detailed analysis of the use of Lean manufacturing approaches to improve operational efficiency and minimize waste in the production processes of a sugar packaging company situated in South Africa. Faced with obstacles in fulfilling waste reduction targets and improving operational efficiency, the study attempted to carefully identify underlying sources of waste and implement Lean concepts, notably the DMAIC technique. The study used a range of Lean problem-solving approaches, beginning with an ABC analysis to identify Stock Keeping Units (SKU) with the greatest waste levels, followed by a mix of the 5- Whys probing methodology and Ishikawa diagrams to go deeper into waste reduction initiatives. Matrix prioritization was then used to prioritize actions and implementations that address identified inefficiencies and issues, leading to the creation and execution of an implementation strategy. During the improvement phase, waste was significantly reduced, notably in the 500g stock-keeping unit. Despite encountering obstacles associated with 1 kg SKUs, due to variances in the Bill of Materials (BOM), significant progress was accomplished. The DMAIC framework offered an organized method that included problem identification, process evaluation, data analysis, improvement implementation, and control installation. The study indicated significant waste levels, which were above weekly targets, resulting in a 70% production efficiency, (or 30% inefficiency), emphasizing the need for process improvements. Among other recommendations, the study suggests improving supervisor handover methods and introducing non-conformance reports (NCRs) to increase supplier responsibility and raw material quality. Supplier participation in performance reviews emerged as a crucial driver in dramatically decreasing waste and increasing production efficiency, resulting in a remarkable 20% improvement in production efficiency, thus raising the production efficiency levels to 90%. In essence, this study sheds light on the efficacy of the DMAIC methodology within the sugar company, offering practical insights into enhancing supply chain efficiency and minimizing waste. By targeting significant process inefficiencies, the research contributes to enhancing sugar production operations, benefiting stakeholders, and bolstering industry competitiveness. The results advocate for the adoption of Lean methodologies to optimize production processes and enhance profitability.
Experimental investigation of epoxy-based foam composites for buoyancy applications
(2025) Ajayi, Ayodele Abraham; Mohan, Turup Pandurangan; Kanny, Krishnan
Selection of appropriate materials for composite design is very crucial in critical engineering applications such as aerospace, marine and automobile industries. This study focused on developing lightweight hybrid-filled foam composite panels with enhanced mechanical and thermal properties. Hollow glass microspheres (HGM) and nanoclay were the fillers used in the foam core. The HGM content was varied from 1wt.% to 3wt.% in foam composites panel while nanoclay content was varied from 1wt.% to 5wt.% in each of the HGM-filled series of foam composites panel, these foam composite panels were fabricated using a conventional resin casting method. These hybrid-filled foam panels were also reinforced with banana fibres as facesheet in the sandwich composites. Comprehensive characterization was carried out on the foam composite panels, this involve investigating their physical properties. The results obtained showed that tensile and flexural strength improved by 12% and 23.1% respectively with the infusion of hybrid fillers content of 3%wt.HGM+1%wt.clay and 1%wt.HGM+1%wt.clay into the epoxy when compared to neat epoxy. Thermal strength was optimum with infusion of 1%wt.HGM+5%wt.clay into the epoxy while the buoyancy results revealed that the sample with 3%wt. hollow glass microspheres concentration has the highest buoyancy due to the low density of the HGM used which is 0.19 g/cm3 and because sample 3%wt.HGM has the highest concentration of HGM with the respect to series of samples considered in this study. Similar trend of improvement in mechanical properties and physical properties was observed when the fabricated hybrid-filled foam panels was used as core in the sandwich composites developed which resulted to 22.11% and 29.53% improvement as flexural strength and tensile strength while there was 32.26% improvement in the impact energy. Also, there was 8.61% reduction in the water uptake. Furthermore, the tensile and flexural results was validated numerically by using finite element method and abaqus® 6.13 software and this revealed that most of the modelled samples are stronger than the experimental tested samples with up to 9% increase from experimental values obtained because of limitation in some parameter estimation of the numerical model such as the thermal properties, perfect contact and linear failure criteria. Since the improvement in mechanical and thermal properties has been established, the composite panels developed are suitable for applications in manufacturing ship propellers. Future studies aims to improve the fire retardation of sandwich composites for marine applications
An evaluation of factors triggering accidents on construction sites
(2025) David, Opeyemi Ayobami; Anugwo, Iruka C.
The Construction Industry (CI) continues to be one of the most physically demanding and risky industries, especially in developing countries where construction activities are more labor-intensive and key issues of health and safety are not adequately addressed when compared with construction practice in the developed countries. Reports of fatal occupational health and safety incidents in the South African construction industry indicate an increase in construction site accidents. This study aims to identify key factors contributing to construction site accidents and propose effective management strategies for mitigating occupational injuries in KwaZulu Natal's construction sector. Thus, this study adopted a quantitative research method, utilising the questionnaire survey as a data collection tool. A purposive sample size of 100 South African Council for the Project and Construction Management Professions (SACPCMP) practitioners were recruited as respondents. Out of the 100 questionnaires distributed among the respondents, only 65 were filled out, returned and valid, yielding a response rate of 65%. The data collected was analyzed using percentages, mean scores and standard deviations, and all the questions contained in the questionnaires were rated using the SPSS statistical package. Study findings indicate that poor scaffolding, contact with energized power sources, and substandard materials significantly contributes to construction site accidents. These issues have key resultant effects such as the cost of case litigation processes, damage to plant and equipment, damage to the reputation of the employer, settlement payments for injuries and death, and the disruption of site operations. This study recommends enhanced training, stricter safety regulations and improved site inspections as key measures to reduce accident rates. However, the study further recommends structured training programs, policy enhancements and stricter enforcement of safety standards to mitigate site accidents and improve construction safety culture in South Africa
Optimization of photocatalytic degradation of wastewater using oxide and non-oxide photocatalysts
(2025) Munien, Caressa; Rathilal , Sudesh; Tetteh, Emmanuel Kweinor
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
Climate change modeling for water resources management : Tana Sub-Basin, Ethiopia
(2025) Tesfaw, Bewuketu Abebe; Dzwairo, Bloodless; Sahlu, Dejene
This study, conducted in the Tana Sub-basin, Ethiopia, aimed to model the impact of climate change on water resources management. The Soil and Water Assessment Tool (SWAT), SPI generator, and RStudio were employed to conduct a comprehensive analysis of climate variability, hydro-climatic extremes, and the impact of land use land cover change on water resources within the region. The findings highlight the significant impacts of both climate variability and land use land cover change on water resources management in the Tana Sub-basin. Changing climate patterns and hydro-climatic extremes were identified as key factors posing increasing challenges to water availability and sustainable management within the region. In analyzing the variability and trends of climate parameters in the Tana Sub-basin, various statistical methods and indices were employed to assess precipitation and temperature patterns. The findings indicated a statistically non-significant increasing trend in rainfall across the Sub basin, with values ranging from 1.64 to 5.37 mm/year. With regard to temperature, an increase was observed, but it was also not statistically significant. The seasonality index ranged between 0.87 and 1.03. In 36.69% of the Sub-basin, rainfall occurs in marked seasonal patterns with a long dry season and the remaining 63.31% is concentrated in three or fewer months, indicating a different rainfall distribution pattern. The assessment of precipitation concentration found that 57.5% of the rainfall data exhibited strong irregular concentration; 41.5% showed irregular concentration, and 1% exhibited moderate concentration. This decreasing trend in projected mean annual precipitation and increasing trend in temperature under the RCP4.5 and RCP8.5 scenarios from 2020 to 2100 indicated significant changes in climate conditions in the Tana Sub-basin. In conclusion, the study underscores the presence of climate change, variability, and trends in the Tana Sub-basin, highlighting the need to align agricultural and water resource management practices with the observed climate variability. Hydro-climatic extremes in the Tana Sub-basin, including drought events, were investigated using several statistical measures and tests including coefficient of variation, seasonality index, precipitation concentration index, Mann-Kendall trend test, and Sen’s slope estimator. Three categories of drought were identified: meteorological drought, agricultural drought, and hydrological drought. The frequency of meteorological drought ranged from 1.05% to 10.04%, agricultural drought from 1.26% to 12.21%, and hydrological drought from 0.21% to 14.5% in the study area. The variability in drought occurrence indicates that certain areas and seasons in the Tana Sub-basin are more susceptible to drought conditions than others. The observation of a potential trend in drought and wet extent occurrences in the study area until 2100 suggests that it may experience significant shifts in hydro-climatic patterns due to climate change. This highlights the importance of considering both spatial and seasonal patterns when assessing drought risks and implementing appropriate measures for water resource management and agricultural practices. In conclusion, the study emphasizes the significance of understanding spatial and seasonal variations in drought occurrence and aligning agricultural practices and water resource management accordingly. This study also assessed the impacts of land use land cover change on water resources using the Soil and Water Assessment Tool. Three land use land cover maps (1986, 2000, and 2014) were analyzed to assess and quantify the changes and their impact on water resources. The findings indicated that changes in land use land cover have a significant impact on various components of the water balance in the study area. Compared to the baseline year of 1986, the average annual water yield increased by 14.88% and 12.6% in 2000 and 2014, respectively. Baseflow exhibited an increase of 18.4% in 2000 but decreased by 7.16% in 2014. Surface runoff increased by 12% and 16.16% in 2000 and 2014, respectively. Evapotranspiration decreased by 18.39% and 13.49% in 2000 and 2014, respectively. The expansion of cultivated land and the decline of forestland and grassland have implications for water resources and hydrological processes. The study thus demonstrates that land use land cover changes in the Tana Sub-basin have significant implications for surface runoff, water yield, evapotranspiration, and baseflow. The analysis of water consumption by different sectors in the Sub-basin in 2020 indicated total annual water consumption for irrigation and horticulture of approximately 555.76 and 46.52 MCM, respectively. Livestock consumes about 31.78 MCM annually. Urban and rural domestic iii water consumption is estimated to be around 22.03 and 33.43 MCM/year, respectively. The highest water-consuming sectors in the Sub-basin are rainfed agriculture and hydropower, accounting for more than 3,700 MCM annually. The projected increase in water demand, as indicated by the estimated water requirements of 6079.01 MCM in 2025, 6423.99 MCM in 2030, and 7519.93 MCM in 2035, emphasizes the urgency of sustainable water resource management. The study proposes adaptive strategy options for integrated water resource management as a crucial step in addressing the scarcity of water and ensuring sustainable use of water resources in the area. Assessing and updating water demand and available water resources are fundamental for informed decision-making and effective management of water resources in the Tana Sub-basin. Implementation of the adaptive strategy options outlined is essential to mitigate the challenges posed by increasing water demand and consumption, ultimately contributing to sustainable management of water resources in the region
Methanation of CO2 over nickel and molybdenum bi-metallic catalyst system supported on activated carbon
(2025) Akpasi, Stephen Okiemute; Kiambi, Sammy Lewis; Isa, Yusuf Makarfi; Mahlangu, Thembisile Patience; Ngema, Peterson Thokozani
The escalating environmental impact of CO₂ emissions has driven the demand for innovative solutions to capture and convert CO₂ into useful energy forms, with CO₂ methanation standing out as a viable approach for generating methane (CH₄) as a clean fuel. This research focuses on developing and evaluating bimetallic Ni–Mo catalysts supported on activated carbon (AC) for CO₂ methanation, exploring the effects of Mo concentration and synthesis techniques on catalytic performance. The catalysts, synthesized with a Ni base of 13 wt.% and Mo as a promoter (5–11 wt.%), were prepared using three distinct methods: incipient wetness impregnation (IWI), sol-gel (SG), and mechanical mixing (MM). These methods provided a range of catalyst properties, allowing for a thorough investigation of how synthesis conditions influence activity, stability, and CO₂-to-CH₄ conversion efficiency. Advanced characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS), were employed to reveal the structural, morphological, and electronic properties of the catalysts. The introduction of Mo significantly modified the Ni/AC catalyst, enhancing pore size, and active site dispersion. Results indicated that optimal Mo concentration, specifically 7 wt.%, improved Ni dispersion and electron transfer properties, reducing the catalyst’s activation energy for CO₂ methanation to 54.6 kJ/mol, compared to 115 kJ/mol for undoped Ni/AC. This facilitated superior catalytic activity, with Ni-7%Mo/AC achieving a high CO₂ conversion rate of 92% and CH₄ selectivity of 80% at a moderate reaction temperature of 250 °C. Among the preparation techniques, the incipient wetness impregnation (IWI) method yielded the most promising results, with the Ni-7%Mo/AC catalyst synthesized via IWI showing the highest CO₂ conversion (56%) and (>95%) CH₄ selectivity at 350 °C. This enhanced performance is attributed to improved metal dispersion, stronger metal-support interactions, and structural stability, resulting from the IWI method. The sol-gel and mechanical mixing methods, while effective, demonstrated lower CO₂ conversion rates of 51.4% and 51.2%, respectively, under similar conditions. These variations highlight the critical role of synthesis techniques in optimizing catalyst performance for CO₂ methanation. To complement the experimental findings, an informetric analysis was conducted on global research trends in molybdenum-enhanced Ni-based catalysts for CO₂ methanation. This analysis utilized VOSviewer and RStudio to identify publication trends, collaboration networks, and research focus areas across highly cited studies from 1994 to 2023. The results highlighted an increasing interest in Mo-doped Ni catalysts, particularly for their ability to enhance CO₂ methanation activity, stability, and resistance to deactivation through sintering and coking. The bibliometric insights highlighted the relevance of Mo in creating efficient, long-lasting catalysts and identified key contributors and leading publications in the field. A review of AC-based materials further illustrated their potential for sustainable CO₂ methanation applications, emphasizing AC’s large surface area, porosity, and cost effectiveness as a catalyst support. The role of AC in enhancing catalyst stability and facilitating CO₂ adsorption positions it as an ideal material for carbon capture and utilization (CCU) technologies. Despite these advantages, challenges remain in optimizing the catalyst formulation for industrial-scale applications, particularly in maintaining stability and minimizing energy requirements. Conclusively, this study demonstrates that Ni-7%Mo/AC, synthesized via incipient wetness impregnation, is an optimal catalyst for CO₂ methanation, achieving high efficiency in converting CO₂ to CH4. These findings not only advance the understanding of CO₂ methanation over Ni-Mo catalysts but also establish a foundation for scaling up this process to support global sustainability goals.
Application of chitosan-carbon nanotube hydrogel beads composite in the removal of antibiotic compounds and perfluoroalkyl substances from aqueous solution
(2024) Khumalo, Siphesihle Mangena; Rathilal, Sudesh; Bakare, Babatunde Femi
The environmental occurrence of antibiotics and perfluoroalkyl acids (PFAAs), particularly in portable water sources, is very evident that current wastewater treatment plants cannot completely eradicate these emerging contaminants of environmental concern. On the other hand, long term exposure to these contaminants poses serious health risks to human and aquatic life. Available literature suggests that antibiotics and PFAAs can be eradicated by solid-liquid adsorption. Therefore, there is an urgent need to develop environmentally green and cost-effective adsorbents for the remediation of antibiotics and PFAAs. As such, the present study focuses on investigating the treatment efficiency of chitosan-carbon nanotube (CCNT) hydrogel beads for the removal of antibiotics viz. amoxicillin (AMX), ciprofloxacin (CIP), and sulfamethoxazole (SMX) as well as PFAAs i.e., perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) from synthetic aqueous solutions. The scope of the present work includes elucidating the adsorption kinetics, isotherms, thermodynamic parameters as well as breakthrough curves for the uptake of AMX, CIP, SMX, PFOS and PFOS on CCNT hydrogel beads. Moreover, Monte Carlo simulations were performed to elucidate the interaction of PFOA, PFOS and sulfamethazine (SMT) with polyethylene (PE) and polypropylene (PP) relative to water. Herein, CCNT hydrogel beads were synthesised using a two-step precipitation approach and analysed using Fourier transformation infrared (FTIR) technology. From the FTIR results it was evident that the synthesised model adsorbent was characterised with strong peaks of carboxylic and hydroxyl functional groups which were essential for the uptake of the model adsorbates i.e., AMX, CIP, SMX, PFOA and PFOS. Post the adsorption process, band stretches were observed cementing the uptake of the model adsorbates on CCNT hydrogel beads. Single adsorption kinetics experimental data for the uptake of AMX, CIP, SMX, PFOA and PFOS were well fitted by the nonlinear pseudo-first order (PFO) kinetic model recording R2 values of more than 0.9 for all model adsorbates. It is worth noting that the competing PFO and pseudo-second order (PSO) kinetic models were validated by applying the Bayesian Information Criterion (BIC) as a statistical analysis parameter. Furthermore, the findings of the present study from the Weber-Morris kinetic model suggest that multiple processes were limiting the overall adsorption rate of AMX, CIP, SMX, PFOA and PFOS on CCNT hydrogel beads. Adsorption isotherm studies were conducted for a temperature range of 283 K, 293 K and 303 K for a contact time of 24 hours for AMX, CIP, and SMX, and 168 hours for PFOA and PFOS. The findings of the present study suggest that AMX, CIP, SMX, PFOA and PFOS single adsorption experimental data were well fitted by the nonlinear Freundlich isotherm model suggesting the heterogeneity of the surface as well as the exponential distribution of the active sites of the model adsorbent. On the other hand, the binary and ternary AMX, CIP, and SMX adsorption experimental data were well fitted by the nonlinear competitive extended Sips adsorption isotherm model. Furthermore, results for the binary and ternary adsorption systems explicitly demonstrated that the multicomponent adsorption systems exhibited both antagonistic and synergistic effects on the uptake of AMX, CIP and SMX. Interestingly, binary adsorption experimental data for PFOA and PFOS were well fitted by the extended-Langmuir isotherm model (R2=0.996 for PFOA and R2=0.995 for PFOS) and extended-Sips isotherm model (R2=0.996 for PFOA and R2=0.997 for PFOS), with the system strictly exhibiting antagonistic effects for the uptake of one adsorbate in the presence of another adsorbate. From thermodynamic studies, it is evident that the uptake of AMX, CIP, SMX, PFOA and PFOS is an endothermic process, and it cannot be explicitly classified as a chemical nor physical adsorption process but as a physicochemical adsorption process. The presence of sodium chloride (NaCl) and humic acid (HA) demonstrated antagonistic effects on the uptake of AMX, CIP and SMX by CCNT hydrogel beads due to formation of aggregates with an increase in ionic strength. Single factor analysis of variance results recorded p-values of less than 0.05 for the uptake of AMX, CIP and SMX indicating that there was a statistical difference between the means of the independent and depended variables, thus cementing the negative effect of increasing ionic strength on the uptake of the mode adsorbates. However, NaCl ions exhibited minimal competitive effects with adsorbate molecules for active adsorption sites on CCNT hydrogel beads compared to HA. On the other hand, the presence of NaCl as a competing ion exhibited synergistic effects in the uptake of PFOA and PFOS from aqueous solutions. Furthermore, for the present work, breakthrough curves from the experimental data were well fitted by the Thomas model recording R2 and adjusted-R 2 values of greater than 0.9 for all adsorbates investigated indicating that the breakthrough curves for the present work can be described by a symmetrical function. Additionally, the breakthrough points time predicted by the Thomas model was aligned with the experimentally determined breakthrough points time cementing its practical utility and superiority over the log-Gompertz and Bohart-Adams models. On the other hand, from the Monte Carlo simulation results, it is evident that, in an aqueous environment, both PFOA and PFOS may be taken up preferentially by PP and PE, although less strongly by PE. The degree of polymerisation of PE and PP did not significantly influence the observed behaviour. In terms of sorption affinity, the observed affinity was PFOA>PFOS>SMT which was consistent for both PE and PP. Based on the results obtained, it was concluded that CCNT hydrogel beads composites have the potential to be applied as adsorbents for the removal of antibiotics and PFAAs from aqueous solutions. Furthermore, the simulation results obtained suggest that Monte Carlo simulations in Material Studio can be used as an effective tool in elucidating the interaction between antibiotics and PFAAs with microplastics relative to water as co-existing contaminants. Therefore, the findings of the present work have successfully addressed the research questions for the current study
Microalgae growth in industrial wastewater for the production of hydrocarbons
(2025) Kukwa, Donald Tyoker; Chetty, Manimagalay
Microalgae have demonstrated unique abilities to photosynthesise the conversion of biodegradable organic materials and inorganic carbon to value-added biomass because dissolved nitrogen and reactive phosphate are present in the cultivation medium. The absence of a breakthrough in biomass production that would enable it to meet and exceed the existing fossil energy demand has elicited research into technologies and protocols that would yield competing energy output. The financial and energy implications associated with the technology employed for biomass harvesting would significantly contribute to the overall cost of the process. Would the microalgae strains that exhibit high growth rates and lipid content, as well as accommodate culture conditions, enhance biomass and lipid productivity? The goal of this study was to provide microalgae with nutrients from industrial wastewater while also producing hydrocarbon compounds that could have positive social effects. A tailored airlift-raceway photobioreactor was utilised to grow microalgae in industrial wastewater after the wastewater was characterised and the optimum conditions for microalgae development were investigated. The resulting production of hydrocarbon derivatives was optimised. Wastewater from the sugar refinery, brewing industry, and dairy industry was characterised by its physical, chemical, mineral, and biological properties using conventional methods. The different industrial wastewater sources were tested for microalgal growth rate and biomass output. The generated biomass was assayed for carbohydrates, lipids, and protein contents of the microalgae strains, and the wastewater that gave the highest biomass and lipid yields was used for advanced cultivation techniques. After careful consideration, the brewery wastewater was found to be the most effective wastewater for microalgae growth and was thus selected for this investigation. Using a novel airlift-raceway photobioreactor system, Scenedesmus sp. biomass was produced in brewery wastewater using optimised conditions. Also, the biomass of a microalgae consortium, native to Durban, South Africa, was produced, leading to hydrocarbons and hydrocarbon derivatives using nutrient-enriched brewery wastewater. This study investigated these capabilities to sequester heavy metals and other pollutants from brewery wastewater and sparged carbon dioxide gas. The light was sourced from 40 W fluorescent tubes, which were powered by a 210 V supply and used at different electromagnetic frequencies ranging from red to blue in a novel airlift raceway system for microalgae cultivation. The microalgal biomass, which was harvested by filtration, was freeze-dried and the surface morphology was analysed using the scanning electron microscope (SEM). The microalgal lipid was extracted with a hexane-methanol solvent system by the soxhlet technique. The morphology of the extracted biomass was analysed using SEM, and the composition of the microalgae oil was analysed using gas chromatography-mass spectrometry (GC-MS). Investigations revealed that the sugar wastewater (SWW) used did not support microalgal growth. However, dairy wastewater (DWW) only supported microalgal growth to some extent, while brewery wastewater (BWW) was best suited for the growth of Scenedesmus sp. and the microalgae consortium. The BWW was nutrients enriched through the oxidation pond, thus raising the influent NO3 - -N (4.98±0.13 mg/L), PO4 3- (13.34±0.48), BOD (35±19), and COD (3979±3) to NO3 - -N (15.98±0.91), PO4 3- (39.93±1.83), BOD (279±10), and COD (5855±4), respectively. GC-MS analysis of the oil extract of the microalgae biomass showed the presence of saturated, monounsaturated (MU), and polyunsaturated (PU) fatty acids in both Scenedesmus sp. and the microalgae consortium, and the presence of an isolated C4 iv and C8-C38 hydrocarbons and hydrocarbon derivatives, mostly fatty acid esters, in the microalgal oils. Nutrient enrichment of the brewery wastewater enables microalgal growth sustainably, thus encouraging lipid accumulation. Using the novel airlift-raceway photobioreactor in this study changed the mass transfer dynamics due to the enhanced hydrodynamics of the novel reactor. Because of this, it was simpler for light and nutrients to reach every area equitably, which is what propels the formation of biomass. The dominance of fatty acid esters in the microalgal oil demonstrates that the protocols adopted in this study can serve to save on the cost of the transesterification step in the production of biodiesel and other useful bio-products. This serves as a major contribution to the body of knowledge on this subject.
A feasibility study for the development of an automation tender processes : case of KwaZulu-Natal Department of Public Works
(2024) Mhlongo, Scelo; Aiyetan, Ayodeji Olatunji
The standard operation procedure provides an organized foundation for the organization's infrastructure supply and maintenance. This framework, which is broken down into phases, includes processes, methods, and procedures that are methodical, regulated, consistent, unified, and readily auditable. This study aims to investigate factors that militate against tendering processes, with the view of developing an automation system of tendering processes at the KwaZulu-Natal (KZN) Department of Public Works (DPW), South Africa (SA). The sample size consists of architects (50), quantity surveyors (50), contractors (100) and cconstruction managers (100) that were selected using the convenient sampling technique due to the small nature of the study. The data analysis was conducted using descriptive statistics. Findings of the study include the occurrence of corruption; and political and unethical practices as the factors causing poor tendering at KZN DPW. This results in time and cost increases. Based on these, the study developed an app to automate the processes of tendering at the processes at KZN DPW, SA. The study also finds that benefit accrues from automated tendering, which are reduction in corruption and affords transparency. The study recommends the adoption of the app developed for tendering practices the procurement of projects at KZN DPW, SA.
The coagulation of wastewater using biowaste materials as coagulants
(2025) Ngomane, Londiwe Zikhona; Mahlangu, Thembisile Patience; Tetteh, Emmanuel Kweinor; Rathilal, Sudesh
In recent years, there has been a growing societal, governmental, and industrial concern about chemical and biological contamination of water. Numerous domestic and industrial operations generate wastewater that contains undesirable toxic contaminants. Chemical coagulants (aluminium and iron-based salts) effectively pre-treatment water and wastewater via coagulation and flocculation. Nevertheless, accumulating these chemical coagulants in the form of sludge and metal oxides significantly affects the environment, as well as human and aquatic life. Against this background, along with biowaste generation and the desire to meet the United Nations Development Goal on Clean Water and Sanitation (UN SDGs#6,9 and 12). Addressing chemical coagulant challenges with alternative solutions, such as using biowaste as coagulants, comes in handy. Therefore, this study aimed to examine the potential of banana peel, eggshell, and seashell powder as substitutes for traditional coagulants in water and wastewater treatment. The biowaste materials (banana peel, eggshell and seashell) underwent calcination at 400°C- 800°C for 2 -3 hours. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Brunauer Emmett Teller (BET), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to analyse the morphology, elemental composition of the structure, the pore surface area, the functional and molecular properties and the crystal structure, respectively. The overall analysis demonstrated the calcination of the engineered biochar was successful. Among the samples, the calcined banana peel was found to have the highest BET surface area of 4.3889 m2 /g, and the peeks on the XRD showed that calcined banana peels have the presence of calcium and potassium. The observed functional groups included O-H, C-O and C-H groups. This was followed by a feasibility study via the coagulation process using the calcined and uncalcined bio-coagulants. The results affirmed that these bio-coagulants are suited for wastewater treatment. In the preliminary studies, the removal efficiencies for turbidity and chemical oxygen demand (COD) were over 80% between the 0.8 – 8 g/L dosage range. The response surface methodology (RSM) was used for the optimisation process with an input variable coagulant dosage (1 g/L – 6 g/L), mixing speed (30 rpm – 150 rpm), mixing time (2 min – 15 min), and settling time (20 min – 120 min) and colour, turbidity and COD removal as responses. The Box-Behnken design response model had a correlation factor (R2 ) of over 0.9 at 95% confidence level. The optimum conditions were 1.6963 g/L (coagulant dose), 119.796 min (settling time), 2.25 min (mixing time), and 30 rpm (a mixing rate), achieving a removal efficiency of 92.39% COD removal, 99.77% Turbidity removal and 104.59 % colour removal at a desirability performance of 100%. The optimum conditions were then validated with various bio-coagulants for the removal of the physiochemicals (COD, Turbidity, and colour) and other emerging contaminants such as phenol, phosphate, nitrate, and ammonia. The response model's predicted results were in total agreement with the experimental results, with less than 5% deviation. In addition, the calcined seashells had the best removal efficiency, with over 80% removal for phenol, phosphate, and ammonia and under 60% removal for nitrates. The findings of this research show that bio coagulants (eggshells, seashells and banana peels) have valuable potential to be substituted for conventional coagulants in the water sector. Therefore, exploring if their economic and environmental viability for water and wastewater treatment is feasible for adaptation and implementation by policy makers and stakeholders is recommended.
Investigating the efficacy of the Bachelor of Engineering Technology degree in Mechanical Engineering at the Durban University of Technology
(2024) Sheoratan, Shoreek; Roopchund, Rishen; Maladzhi, Rendani Wilson; Graham, Bruce
As of 2018, the Durban University of Technology’s (DUT) Mechanical Engineering Department offers a Bachelor of Engineering Technology (BET) degree, as well as master’s (MEng) and doctorate (DEng) degrees. DUT subsequently launched a BET honour’s qualification in 2022, which serves as a stepping stone from the BET degree to the master’s degree. The BET degree was initiated for several reasons to replace the existing National Diploma as part of the aligned process to the newly introduced Higher Education and Qualifications Sub-Framework (HEQSF). The BET degree also constitutes those academic requirements necessary to apply for registration as a Professional Engineering Technologist with the Engineering Council of South Africa (ECSA). This dissertation investigates the success of the new degree by assessing the academic success of Mechanical Engineering students enrolled in the BET programme. The investigation is not limited to students who have successfully completed their studies, but includes students who have begun their studies and have failed to complete them, or do so in a reasonable amount of time, for several reasons. The primary data source for the research included information from the institution's Management Information System (MIS). Conforming to a positivist paradigm, the research employed mixed methods methodology, comprising five sub-studies to understand student success in the BET programme. The first sub-study involved success rate analysis. Since the commencement of the BET degree in 2018, the success rates of the cohorts (2018, 2019, 2020, and 2021) were analysed to assess programme efficacy. The second sub-study concerned the relationship between National Senior Certificate (NSC) results and students’ performance in first-year modules. Students' NSC results were compared to their first-year module outcomes to determine the correlation between NSC Maths, NSC Physics, NSC English, and the appropriate first year engineering modules. The third sub-study relates to Graduate Attributes (GAs) and their implications on student throughput. The concern was that if a student failed a GA, they would also fail the module. An investigation was conducted to determine whether students are failing primarily because of failing GAs. The fourth sub-study related to selected modules offered in successive semesters (‘back-to-back’ modules). The purpose of which was to determine whether offering Strengths of iv Materials I and Mechanics of Machines I in the first semester resulted in higher success rates, and whether this intervention ought to be maintained. The fifth and final sub-study related to the student success in National Diploma (ND) vs. BET modules. Student success rates of BET modules that were deemed similar to modules offered within the ND qualification were compared and analysed. Performing these five sub studies resulted in insights into the success of the BET Mechanical Engineering programme at DUT, and is anticipated to enable DUT’s Mechanical Engineering Department to make informed decisions in addition to placing interventions in the programme to ensure greater student success. The content comprising this dissertation was disseminated into one abstract (Walker, Graham and Sheoratan 2022a), one poster (Walker, Graham and Sheoratan 2022b) and one full conference paper (Walker, Graham and Sheoratan 2023) and one journal article (2024 – still under review). See Appendix D (Publications).
DC microgrid energy optimization
(2025) Jiyanen, Muziwenkosi; Pillay, N.; Sewsunker, R.
Microgrids that generate electricity using photovoltaic panels or wind turbines and batteries, provide a viable solution to meet low to moderate energy needs in rural, remote and informal settlements. However, these solutions are limited because they depend on the availability of sunlight or wind. To solve these limitations, researchers have proposed hybrid systems that combine multiple energy sources and can be more efficient than battery-powered photovoltaic or wind systems. These hybrid systems use dynamic dispatching to optimize the overall cost and performance of the microgrid. Energy management systems are widely used to achieve this dynamic energy distribution, including load profiling and intelligent decision-making for energy distribution. While many energy management systems focusing on automated demand side management have been deployed worldwide to optimize microgrids, less work has been done in South Africa. This research is focused on designing a hybrid PV-driven battery and fuel cell backup system, initially concentrating on sizing the PV, battery, and fuel cell. The focus then shifts to developing an energy management system. The proposed system follows a low-power provision in a 48 VDC format, offering electricity for lighting, computing, entertainment devices, and communication modules. Seven rural households were chosen for the study, collectively consuming 8.64 kWh/day. The efficacy of the microgrid is examined with and without demand-side management and considering the impact of load scheduling. The findings revealed that reducing energy demand by the demand side led to an increase in current and output power due to the proportional relationship between current and power, while the bus voltage remained constant at 48V DC. Furthermore, an increase in loads resulted in a decrease in output power. The simulation was carried out using the MATLAB® Simulink™ environment.
Infinite dilution activity coefficient measurements of different organic solutes in cyrene as a potential green solvent for chemical separation processes
(2025) Danisa, Melusi; Ngema, Peterson Thokozani; Nkosi, Nkululeko; Ramsuroop, Suresh
Biofuels are increasingly consumed globally. The search for eco-friendly solvents to replace conventional organic solvents derived from fossil fuels continues to grow. Biofuels derived from plant dry matter are abundantly available, which justifies researchers' ongoing interest in them. Researchers are exploring several options to facilitate the easy integration of this resource into existing systems. The focus of this project as a replacement for volatile organic compounds VOCs, a bio-derived solvent (BDS), cyrene, classified as dihydrolevoglucosenone by evaluating its extractive efficiency in this study for various separation using pre-screening technique known as gasliquid chromatography (GLC) instead of directly testing cyrene as a potential alternative to conventional solvents. In contrast to direct methods, GLC offers the advantage of assessing numerous separation problems in a shorter period than direct methods. Cyrene’s intermolecular interaction strengths with 32 volatile organic compounds (i.e. alkanes, alkenes, alkynes, cycloalkanes, ketones, alcohols, aromatics, heterocyclics, nitrile, esters and water) were assessed using infinite dilution activity coefficients (IDAC) measured at T = (303.15 to 333.15) K and 101.3 kPa. Further analysis of IDAC data was performed to determine the chemical thermodynamic properties, i.e., partial excess molar properties (∆𝐻1 𝐸,∞, E, T S ref i   ,∆𝐺𝑖 𝐸,∞) obtained at infinite dilution, to assess the cyrene and solute mixtures and quantify their nonideal behaviour in real mixtures. Addition to this, Aspen Plus and COSMO-RS software were used to build thermodynamic models in conjunction with the experimental data to make predictions.
Development of an adaptive protection scheme for compensated transmission network with high level penetration of renewable energy sources
(2025) Mazibuko, Ntombenhle; Akindeji, Kayode Timothy; Moloi, Katleho
The 2030 Agenda for Sustainable Development, adopted by all United Nations Member States in 2015, presents a unified framework designed to promote peace and prosperity for individuals and the planet, both in the present and for future generations. At the heart of this agenda are the 17 Sustainable Development Goals (SDGs), which call for immediate action from all countries regardless of their development status through a global partnership. Specifically, SDG 7 seeks to guarantee access to affordable, reliable, sustainable, and modern energy for everyone by 2030. South Africa, recognized as one of the most developed nations in Africa, is also the continent's largest energy consumer. The combination of a growing population and an ongoing power crisis has resulted in heightened electricity demand and a need for alternative energy solutions. In recent years, the country has launched various projects focused on renewable energy sources (RESs). However, despite these investments, the contribution of renewables—particularly wind, solar photovoltaic (PV), and concentrated solar power (CSP)—remains limited, accounting for only 13.7% of the total energy mix, which decreases to 7.3% when hydroelectric sources are excluded. Nuclear and diesel energy make up 4.6% and 1.6%, respectively. The ongoing gap between energy supply and demand remains a critical issue. Additionally, transmission line compensation techniques have emerged as a promising method to enhance transmission capacity, minimize losses, and improve stability within power systems. Although these technique increases the energy availability factor, they frequently present technical challenges in the routine functioning of power systems, especially regarding network protection systems. Protection is crucial not only for ensuring system stability but also for the safety of equipment and personnel. Fundamental principles of any protection strategy encompass accuracy, selectivity, and reliability. This research introduces a machine learning-based protection scheme tailored for a compensated transmission line within a renewable energy network. Initially, a simple two-bus network is created, and a series capacitor compensation method is integrated to assess the impact of transmission line compensation on protection systems. Data is gathered and utilized across three different machine learning detection and classification techniques: K-Nearest Neighbours (K-NN), Medium Neural Network (MNN), and Quadratic Support Vector Machine (QSVM). Additionally, the network is expanded to incorporate both solar and wind energy sources to evaluate performance with the inclusion of renewables. The classifiers are then tested and fine-tuned for enhanced performance. Performance metrics, including confusion matrix analysis, precision-recall curves, and ROC curves, are employed to assess the effectiveness of each machine learning approach. The results indicate that the accuracy and reliability of protection are influenced by the application of these techniques, as evidenced by the rate of fault misclassification. Moreover, machine learning methods show promise in enhancing the protection scheme's performance for a network architecture that includes a compensated transmission line and renewable energy sources. Among the classifiers, the SVM has emerged as the most effective machine learning classifier, achieving an average accuracy of 99.2%.
Thermochemical conversion of lignocellulosic biomass into biofuels and petrochemicals
(2025) Shezi, Manqoba; Kiambi, Sammy Lewis; Isa, Yusuf Makarﬁ
The depletion of conventional fossil fuel reserves, including oil, gas, and coal, has intensified concerns over environmental sustainability and energy security. Consequently, there has been a substantial shift towards exploring alternative energy technologies and developing sustainable products and processes. Biomass has gained significant traction as a renewable feedstock of interest in recent decades. Bio-oil derived from biomass holds promise for diverse energy production, chemical synthesis, and potential energy carrier applications. However, crude bio-oil exhibits inherent challenges stemming from its physical and chemical properties that preclude its direct integration into existing fuel infrastructures. Notably, the high acidity, low viscosity, high density, elevated oxygen content, substantial moisture levels, low heating value, complex molecular composition, and instability. These drawbacks can lead to issues such as corrosion, coking during upgrading, and difficulties in storage and transport. Addressing these challenges require advanced refining and treatment techniques to enhance the bio-oil's compatibility and usability within established industrial frameworks. Hence, studies that aimed to improve the properties of the bio-oil organic phase were conducted. Initially, the research embarked on catalytic and non-catalytic fast pyrolysis of Giant Reed using a zeolite as a catalyst. The results indicated that the presence of the HZSM-5 catalyst significantly improved the quality of the pyrolysis oil. Catalytic pyrolysis consistently yielded bio-oil with lower moisture content and higher carbon content than non-catalytic pyrolysis. At 550°C and 10 °C/min, the HHV of the catalytic pyrolysis product was 23.0 MJ/kg compared to 21.3 MJ/kg for non-catalytic pyrolysis. Applying the HZSM-5 catalyst at 650°C and 50 °C/min significantly enhanced the production of aromatic hydrocarbons and phenolic compounds while reducing the presence of undesirable oxygenates in the bio-oil organic phase. However, this observation was a trade-off to lower bio-oil yields and high energy consumption due to a high operating temperature. As a result, 550°C and 10 °C/min was considered as the operating condition for bio-oil organic phase production. Another sub-study focused on investigating the effect of periodic variations on the fuel properties of Giant Reed and assessing its influence on pyrolysis product yield, quality, and distribution. This study was carried out after the incineration of giant reed along the river banks in Ladysmith, RSA, with the aim of minimizing artificial flooding occurrence as a result of stormwater drainage blockages. Four periodic variations, late spring (HS-4), late summer (HS1), late autumn (HS-2), and late winter (HS-3), were considered to investigate the effect of characterization, and bio-oil organic phase (BOP) fuel properties. The considered biomasses herein had average calorific values of 18.86 ± 0.05, 19.73 ± 0.05, 19.23 ± 0.04, and 18.44 ± 0.04 MJ/kg during HS-1, HS-2, HS-3, and HS-4, respectively. The biomass, bio-oil organic phase, biochar, and pyrolysis gas were characterized using thermogravimetric analysis (TGA), gas chromatography-mass spectroscopy (GCMS), Fourier transform infrared spectroscopy (FTIR), micro-GC, and scanning electron microscopy (SEM/EDS). The organic phase of biooil was isolated using a 125 ml separating funnel, allowing natural stratification of the immiscible phases. BOP yield increased from 5 to 11 wt% during HS-4 and HS-3, respectively. The increase in the BOP yield correlated with the lignification effect significantly, as shown by the R2 value of 0.97. Higher heating values (HHV) of the BOP ranged from 19.4 ± 0.03 to 22.6 ± 0.02 MJ/kg in relation to the active growth stage and senescence-dormant phase. Physical and chemical properties (TAN, density, viscosity, water content, and CHNS) and chemical compound groups of organic phase bio-oil were analyzed. The produced BOP was rich in phenolics for all considered periods. The effect of harvest time showed that biomass and bio-oil organic phase fuel properties are improved during the senescence-dormant period. As a result, giant reed biomass should be harvested during autumn to avoid incineration that releases carbon dioxide into the atmosphere and will also reduce the occurrence of artificial flooding. Fast pyrolysis of biomass is crucial for sustainable biofuel production, necessitating thorough characterization of feedstocks to optimize thermal conversion technologies. The third study investigated the isothermal pyrolysis of bamboo and pinewood biomass in a sand-fluidized bed reactor to assess biomass suitability for commercial bio-oil production. The pyrolysis products and biomass species were characterized through proximate and ultimate analyses, GCMS, FTIR, SEM/EDX, and structural analysis, to assess their chemical and physical properties. Results indicated that pine bio-oil possesses superior energy density, with a higher calorific value (20.38 MJ/kg) than bamboo (18.70 MJ/kg). Pine biomass yielded greater organic phase bio-oil (BOP) at 13 wt%, while bamboo produced 9 wt%. Energy yields were also notable, with pine exhibiting an energy yield of 15% for bio-oil organic phase (EBOP), compared to 11% for bamboo. The fibrous nature of bamboo biomass resulted in less reacted biomass at constant reaction time due to flow resistance during pyrolysis. Pine bio-oil organic phase (PBOP) demonstrated a higher heating value (23.90 MJ/kg) than bamboo (B-BOP). The findings suggest that while both biomass types are viable renewable energy sources, pine biomass is more favourable for commercialization due to its superior energy properties and efficiency in pyrolysis. Conventional mild hydrotreatment processes of bio-oil present significant challenges of high degree of polymerization, low oil yield, high coke formation, and poor catalyst recovery. To address these challenges, the fourth study looked into investigating and enhancing the properties of raw bio-oil organic phase samples via a solvent-assisted stabilization approach using methanol (METH), ethanol (ETHA), isopropyl alcohol (IPA), and ethyl ether (ETH). Solvents like methanol (METH) and ethanol (ETH), which are highly polar, yielded higher oil fractions (64% and 62% respectively) compared to less polar solvents like ethyl ether (DME) at 59%. Isopropyl alcohol (IPA), with intermediate polarity, achieved a balanced oil yield of 63%, indicating its ability to dissolve both polar and non-polar components. The moisture reduction in stabilized bio-oils followed the order: IPA > ETH > METH > DME, with IPA showing the highest reduction due to its structural characteristics facilitating dehydration. Viscosity reduction varied with IPA > ETH > DME > METH. Carbon recovery in stabilized bio-oils ranged from 65% to 75% for DME, ETH, and METH and was 71% for IPA. The heating values of stabilized bio-oils ranged from 28 to 29 MJ/kg, with IPA-stabilized bio-oil showing the highest value (29.05 ± 0.06 MJ/kg). METH demonstrated high efficiency (74.8%) in stabilizing bio-oil, attributed to its strong hydrogen-donating capability. ETH followed closely at 69.5%, indicating its comparable performance in bio-oil stabilization. With moderate efficiency (69.3%), IPA presented a balanced alternative considering its molecular structure and hydrogen solubility. In contrast, DME exhibited lower efficiency (63.6%) due to its weaker hydrogenation capability and propensity for undesired side reactions. The study suggested that subcritical conditions up to 200°C are adequate for METH, ETH, and IPA in bio-oil stabilization, comparable to results obtained under supercritical conditions. harvest time on biomass fuel properties, pyrolysis product distribution, non-condensable gas
Framework for evaluation of energy sustainability in university students’ housing in Ghana
(2025) Miller, Appau Williams; Anugwo, Iruka Chijindu; Okorie, Victor Nnannaaya; Simpeh, Fredercik
Traditional student housing designs have not adequately addressed sustainability, leading to thermal discomfort, poor indoor air quality, and inadequate acoustic and visual comfort, resulting in negative impacts on students’ health, academic performance, and social well-being. While previous research has largely centered on energy demand, power systems optimization, and usage behavior, less attention has been paid to the role of sustainable student housing design. The study aims to develop a conceptual framework to assess indoor energy sustainability in student housing in Ghana. It examines the impacts of sustainable design on energy consumption, identifies drivers and barriers to sustainable design, and evaluates behavioral control influences on energy consumption in Ghanaian student housing. Grounded in the Theory of Planned Behavior and integral sustainable design, the research adopts a pragmatist approach and uses an explanatory sequential mixed-methods design, combining quantitative and qualitative data. The sample consists of 65 student housing units across Southern and Northern Ghana, involving 340 housing managers, 224 architects, 342 student housing leaders, 65 investors, and 12 energy experts for focus group discussions. The study uses Partial Least Squares Structural Equation Modeling (PLSSEM) with SmartPLS 4 software to analyze the relationship between sustainable housing design and energy consumption. Exploratory Factor Analysis (EFA) identifies the key drivers and barriers to sustainable housing design, and the Relative Importance Index (RII) evaluates the influence of student energy behaviors on energy consumption. Key findings reveal that sustainable design decisions are influenced by building orientation, envelope design, window glazing, indoor circulation area, and floor span. However, issues like low compliance with indoor circulation space and window glazing standards negatively impact energy efficiency. Major drivers for sustainable design include high energy costs, energy-sharing mechanisms, and health and safety concerns. Barriers include high upfront investment costs, lack of knowledge, limited skills, and expensive building materials. The study develops a four-quadrant integrated framework for indoor environmental energy sustainability in student housing, providing a foundation for university management and planning institutions in Ghana. It suggests further research into social, economic, and institutional sustainability, improving compliance with the Ghana Building Code, and fostering collaboration between the Ghana Energy Commission and the Physical Planning Unit.
Corrosion rate measurement of sheet pile wall in the port of Durban
(2025) Nyawo, Mncedisi Mangaliso; Allopi, Dhiren
Ports and harbours are typically located along coastal and inland waterways. Harbours refer to water bodies adjacent to the shore that shelter watercrafts from stormy weather and provide anchorage for ships. Ports, on the other hand, denote infrastructure designed for docking vessels that transport passengers and cargo to and from land. In essence, harbours become ports when they are utilised for commercial activities, such as loading and unloading cargo, embarking passengers, or any other revenue-generating operations. At the Port of Durban, steel sheet piles were installed beneath the quay walls to protect against rising sea levels, prevent soil erosion, and support the riprap beneath the deck of the pile quay wall. However, these steel sheet piles have reached the end of their design life. Furthermore, the thickness of the steel sheet piles at several berths has decreased due to corrosion. The aim of this study was to determine the corrosion rate (mm/year) and estimate the remaining thickness of steel sheet pile walls at Island View Berth 3 and Maydon Wharf Berth 12 in the Port of Durban. This investigation provided an estimation of the quay wall’s functionality and determine whether maintenance, reinforcement, or replacement is necessary. Additionally, the determined corrosion rate will inform future designs of steel sheet piles. Island View Berth 3 was constructed in 1993 using the ARBED BZ 7 sheet pile type, while Maydon Wharf Berth 12 Berth was rebuilt in 2012 with the new HZM/AZ combined sheet pile wall system. The latter utilised over 2 800 tonnes of HZ 1180M A-24 king piles and 440 tonnes of AZ 18-700 sheet pile pairs as intermediate piles. A significant challenge at the Port of Durban was the development of excessive sinkholes behind berths, believed to result from erosion caused by deteriorating sheet pile structures. Currently, the Port lacks mechanisms to measure the remaining thickness of the steel sheet piles or perform underwater maintenance of these structures. Furthermore, no system is in place to monitor or track the condition of the sheet piles, making it difficult to determine when replacement or maintenance is necessary. During the inspections, 42 points were examined: 22 in Island View Berth 3 and 20 in Maydon Wharf Berth 12. Island View Berth 3 was inspected over two days in January 2020, while Maydon Wharf Berth 12 was inspected over 14 days. Prior to measurements, divers cleaned 200 mm x 200 mm patches of the steel sheet pile wall. Marine growths were manually removed using a steel scraper, hammer, and wire brush. The outer flanges surface of the steel sheet pile was cleaned from top of pile to the bottom of sheet pile. An ultrasonic thickness (UT) gauge was employed to assess the remaining thickness of steel sheet piles at both berths. This device emits high-frequency sound pulses through a hand-held probe in contact with the metal, measuring the time taken sound waves to travel through the material, reflect off the back wall, and return to the probe. The remaining thickness was determined by calculating the sound speed in steel and using half the total travel time. Corrosion rates were calculated using the formula icorr =(To−Ta)/t, where To is the original thickness, Ta is the actual thickness, and t is the exposure time in years. This data can inform the design of new steel sheet pile structures for ports. At Island View Berth 3, the average corrosion rate 28 years after installation was 0.0516 mm/year. Maydon Wharf Berth 12 showed varying corrosion rates by zone: 0.0545 mm/year (splash zone), 0.0485 mm/year (tidal zone), 0.0345 mm/year (lowwater zone), and 0.0290 mm/year (immersion zone), with an overall corrosion rate of 0.0466 mm/year. This study highlights significant corrosion variability across studied zones and emphasises the need for a comprehensive maintenance plan. These findings provide essential insights for future design and preservation strategies of marine structures at the Port of Durban.
Assessment of the lower Isipingo catchment’s ability to mitigate flooding, considering the existing drainage system
(2025) Nzuza, Zinhle Nomfundo; Dzwairo, Bloodless
The Lower Isipingo Catchment is located south of Durban in the KwaZulu-Natal Province, South Africa. It presents a particular challenge to urban flood risk. The Lower Isipingo Catchment comprises the split Isipingo and Umlazi River estuarine systems. The significance of the catchment is that it has become one of Durban's most industrially developed areas. The Isipingo wetland was converted into a flatland to facilitate the economic development of industries in the 1940s. The Isipingo Diversion Works System was implemented in 1960 as a flood mitigation strategy using canals at the tail end of the Isipingo and Umlazi rivers. This strategy was not successful, as extreme flooding is a regular occurrence within the Lower Isipingo Catchment, causing constant socio-economic losses and infrastructure damage. The study evaluated the catchment’s capacity to mitigate flooding, considering the existing drainage system. The study's findings can be used to improve the resilience of the catchment against flooding events. The study objectives were made up of three components. The first was to evaluate the effects of urbanisation on the catchment's drainage system. This was achieved by calculating the peak flow. The Rational Method was used to quantify the volumetric flow rate of surface water draining from the catchment area over 20 years. Peak flows were assessed for pre- and postdevelopment scenarios in 2002 and 2022. The catchment was split into four subcatchments: Isipingo 1, Isipingo 2a, Isipingo 2b, and Isipingo 2c. The findings demonstrated that there has been a rise in economic activity through developments in the Prospecton industrial area and the Isipingo Central Business District (CBD) in the lower catchment. As a result, the upper catchment now includes denser residential zones with fewer green spaces and lower surface infiltration. The unit hydrographs show higher peak flows and reduced lag time under post-development scenarios. Isipingo 1 produced the highest increase in runoff flow at 50%, followed by Isipingo 2a and 2b with 33%, and lastly Isipingo 2c with an increase of only 25%. Development in the catchment has led to more impervious surfaces, which has increased stormwater runoff. This increases the vulnerability to flooding as conventional drainage systems do not consider the effects of urbanisation on runoff volume. The second objective was to determine the extent to which solid waste impacts the drainage system’s functionality. This was achieved by physically inspecting the drainage infrastructure using visual inspections. The study found that the system was not functioning at its designed capacity due to the accumulation of debris and waste within the drainage inlets conveyed by runoff in all four sub-catchments. The drainage structures are blocked with silt and debris and damaged in certain instances, preventing the flow of stormwater within the stormwater networks. It was observed that the culverts in Isipingo 2b are under-maintained to withstand the flows and volumes of stormwater. The result of these factors is that stormwater is unable to enter or leave the stormwater systems efficiently, which can further reduce mitigation capacity and increase the risk of flooding. The third objective was to assess the performance of the existing drainage system with varying rainfall data. This was achieved through the completion of a stormwater hydraulic model for the drainage networks. The Personalized Computer Storm Water Management Model detailed the hydrological characteristics of the catchment and the configuration of the drainage network system. The models are based on a 1-hour storm simulation using the 1 in 5-year design rainfall and the 2019 and 2022 flood rainfall experienced on the catchment. The results specified the flooding networks and the severity of flooding, depending on the digital elevation model data and the distribution and intensity of the rainfall. The model’s results indicated that stormwater infrastructure is sufficient to mitigate stormwater runoff for the 1 in 5-year design rainfall and the April 2019 and 2022 flood rainfall. However, due to hydraulic inconsistency of the stormwater network pipe sizes, slopes, cover, and invert levels, the hydraulic capacity has proven to be insufficient in certain areas. This has resulted in localised flooding in Isipingo CBD located downstream in the sub-catchments of Isipingo 1, 2a and 2b along Phila Ndwandwe Road, Thie Road, Clark Road, Pardy Road, and Lotus Road. There is also visible flooding in Isipingo 2c, the Prospecton industrial area, with the following areas being vulnerable: the N2, Prospecton Road, Winter Road, Avenue East Road, Joyner Road, Ocean Road, Delta Road, Duiker Road, and Inner Circuit Road. It was also noted that relying entirely on model outputs and ignoring real-site circumstances might result in an underestimation of flood hazards associated with high rainfall occurrences. The findings of this study can assist eThekwini Municipality to be more proactive rather than reactive to the frequent flooding in the Lower Isipingo Catchment. Knowing the location of the vulnerable areas within the catchment, including the factors increasing the flood risk, can assist in improved resource allocation and preparedness against frequent floods. The implementation of this study’s recommendations could have positive economic, social, and environmental effects on the Lower Isipingo Catchment. Adopting water-sensitive urban design principles with the use of sustainable urban drainage systems is the new approach to the management of stormwater. Treating stormwater as a resource in the water cycle rather than a nuisance. Sustainable urban drainage systems can be retrofitted into the existing drainage network to increase flood mitigation capacity for frequent heavy rainfalls and reduce stormwater contaminants in receiving waters. An all-inclusive strategy that combines modelling with on-site inspections and maintenance will offer a clearer understanding of the system's capabilities and limits, resulting in improved readiness and reaction strategies in the face of changing weather patterns. A holistic approach can be used through cross-sector collaboration amongst various stakeholders to implement innovative institutional structures, policies, and management methods. This network can implement the following: infrastructure planning and upgrading, public participation, early warning systems, stormwater management, and asset management.
Evaluation of enhancement methods for the production of biogas for anaerobic codigestion of sewage sludge with industrial wastewater
(2025) Estrice, Denzil Erwin; Chetty, Maggie; de Koker, T.H.
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.
Spatial planning for electronic communication infrastructure in South African municipalities : a case of the eThekwini Municipality, KwaZulu-Natal, South Africa
(2025) Chetty, Jenisha; Lincoln, Gilberte Marie; Musvoto, Godfrey Gombana
The Fourth Industrial Revolution (4th IR) is marked by the convergence of digital, biological, and physical technologies supported by Information and Communication Technology (ICT). As societies increasingly rely on digital connectivity for economic growth, social interaction, and technological advancement, robust spatial planning frameworks to accommodate this infrastructure become paramount. Spatial planning for electronic communication infrastructure, a component of ICT in the 4th IR, is essential to shape a connected, resilient, and inclusive digital future. Despite the South African regulatory framework’s recognition of ICT’s potential to address socio-economic issues, electronic communication infrastructure delivery falls short due to financial constraints, governance failures, and policy misalignment between the tiers of government. This study focused on the eThekwini Municipality, South Africa's third-largest city, to evaluate spatial planning and statutory processes’ responsiveness and effectiveness in facilitating electronic communication infrastructure development. More specifically, it examined the alignment of the municipality’s spatial plans, policies, and legislation with the national regulatory framework and its goals for ICT development. The study assessed the purpose and influence of statutory planning applications for infrastructure development and drew lessons from international and local precedents to enhance statutory procedures. By addressing these issues, it aimed to identify regulatory and procedural shortfalls and provide recommendations to improve electronic communication infrastructure development in the municipality. These include enhancing alignment with regulatory frameworks originating from national government and adaptive and flexible planning approaches to inform municipal planning and development for ICT and electronic communication infrastructure.

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