Theses and dissertations (Engineering and Built Environment)

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Analysing South Africa’s automotive energy consumption : application of index decomposition analysis
(2021-01) Machivha, Rofhiwa Tevin; Olanrewaju, Oludolapo Akanni
This research focuses on applying the Index Decomposition Analysis (IDA) to South Africa’s automotive industry to decompose energy consumption and further make use of regression analysis to understand how it relates to the economy. South Africa has been going through an energy crisis, which has resulted in ongoing load shedding as a way to manage this crisis. Looking at South Africa’s energy generation, it can be noted that the entire country depends on Eskom as the main supplier and of electricity, but it is unable to keep pace with the demand. The results of the research show that there exists a nexus across all segments between energy consumption and GDP; furthermore, the decomposition results show that energy consumption in some years experienced a reduction. However, it can be seen that an increase in energy consumption year on year is predominant; this then suggests that the reductions experienced were the result of a special event; hence, it can be deduced that overall energy consumption has increased slightly. The increase is as a result of the activity effect which contributed the most towards this whilst the structural effect yielded a negligible contribution. Lastly, the intensity effect contributed to the reduction in energy consumption as a result of sectoral shifts; this reduction contributed towards keeping the overall increase in energy consumption low. This study aimed to outline the differences in energy consumed during the production of different vehicle classes, citing various factors responsible for the changes in energy consumption during vehicle production, raising awareness with manufacturers on the impact industrial energy consumption has on the national energy grid and on advising medium to large manufacturers to become suppliers.
The application of lean principles to mitigate greenhouse gas emissions in an automotive industry
(2020-09) Ramsunder, Keshav; Olanrewaju, Oludolapo Akanni
A common factor for industrial production is energy, and the level of energy consumed is typically used to measure the growth and economic development of countries. However, as the industrial sector expands and makes efforts to gain competitive advantage, there is a growing concern regarding energy consumption and the ecological burden related to energy use. Thus far, industry has relied on the Lean manufacturing paradigm to gain the contemporary benefits of profitability, flexibility, and increased efficiency. More recently, the association of Lean manufacturing and environmental impacts has grown in both the industrial and academic fields. The main aim of this research is to investigate the correlation between lean tools and their effect on Green House Gas emissions, ultimately measuring environmental performance. The research is quantitatively based and entails the study of a weld process production line at Toyota South Africa Motors. The environmental impacts of the production process were observed and measured before and after the implementation of three lean tools: Value Stream Mapping (VSM), Total Productive Maintenance (TPM) and Standardized Work. Comparing the outcomes, the study found significant differences in the pre-test and post-test of each lean technique applied. VSM allows one to visualize and magnify the environmental performance of the process, which allows for simple quantifying of environmental metrics. TPM brings to light that equipment that is regularly maintained to operate at optimum condition reduces non-value adding energy usage. However, in contrast, Standardized Work has shown minimal benefits within the context of this research. The findings of this research are beneficial as they contribute to gaining a better understanding of the way lean tools affect environmental performance. While the study contributes to the current body of knowledge, it can also enlighten Small to Medium Enterprises, practitioners and larger organizations to rethink current strategy and allow for simultaneous implementation of Lean Green operations.
An appraisal of building information modelling technology in building construction and maintenance in Africa : a case of Nigeria and South Africa
(2023-05) Toyin, James Olaonipekun; Mewomo, Modupe Cecilia
Building Information Modelling technology (BIM-T) continues to gain attention. Its adoption creates a platform that allows the built environment professionals to share project information through a common database. At the same time, there is an increased perception that implementing BIM on construction projects will positively influence building production throughout its lifecycle. Recent studies have revealed a low level of BIM implementation in the African construction industry. Currently, the utilisation of BIM for building production has received a significant acceptance rate in developed regions, while in African countries, it is still at an infant stage. Moreover, previous studies have established that BIM application comes with various barriers. These barriers contribute to its low adoption, application and implementation. Nevertheless, there are still some notable benefits and impacts on building production, which have been the main drivers for its continual adoption. Therefore, this study aimed to research BIM-T applications in African countries, focusing on the Nigerian and South African construction industries. The goals are to assess its level of awareness, usage, barriers hindering its application/implementation and benefits accruable with its adoption. BIM impacts the building production lifecycle and determines the strategies to promote its application among construction professionals for sustainable construction in developing countries. To achieve the objective of this research, an extensive review of the literature was conducted on usage, barriers to BIM adoption, application/implementation, benefits of adopting BIM, its impacts on building production, and strategies to promote its application/implementation. A structured questionnaire elicited constructive data from the Nigerian built environment professionals (NIA, NIOB, NIQS, and NSE) and the South African construction-related professionals (SACPCMP). The web-based (Google form) questionnaire was distributed online. According to the distribution among the professionals, 276 and 105 respondents indicated their willingness and availability to participate in the research from Nigeria and South Africa, respectively. The generated data was analysed using the following descriptive measures: mean item score (M.I.S), relative important index (RII), ranking and frequency and quantitative inferential analysis (factor analysis, pairwise comparison, one-way ANOVA and Kruskal-Wallis). It was found that there is a significant increase in the level of BIM awareness among Nigerian and South African construction professionals compared to previous findings. 98.55% and 96.19% of respondents, respectively affirmed that they are aware of BIM. Nevertheless, these findings established that there are still BIM-related barriers peculiar to both countries; the top common three barriers are low computer skills among some of the professionals, habitual resistance to change from the traditional style of design and build, and government's unwillingness to support BIM use. These barriers could be responsible for the professional’s low level of BIM tool usage. The study also revealed that all 13 identified BIM benefits are significantly important in both countries. From this, it could be concluded that BIM application has significantly improved the production of buildings through its contribution to performing tasks from building design to post-construction stages. Finally, the respondents identified the need for foundational knowledge in an educational institution on BIM tool use and its applications as a critical area of focus that could assist the promotion of BIM. This study has extensively documented the various research contributions carried out in this study's area of focus. The preliminary survey result concludes that the findings will assist the professional body in making intelligent decisions and adequate measures to advance the adoption, application/implementation of BIM among their members. It will also inform the institutions about what is required from their construction graduates to improve their employability in the industry.
An appraisal of procurement challenges facing emerging contractors in public sector projects in South Africa
(2024-05) Bangani, Sibabalo Edmond; Mewomo, Modupe Cecilia
Poor participation and performance of emerging contractors in public sector construction projects is currently an issue of major concern in South Africa (SA), as economic development relies mainly on the sustainability of small businesses. While the South African government has endeavoured to make provisions for the advancement of the emerging contractors through the regulatory framework and Section 217(i) of the constitution, earlier studies have revealed that the emerging contractors continue to face several procurement challenges. These procurement challenges have adversely impacted the growth and development of small contractors. Unfortunately, the available provisions in the constitution and the regulatory framework have not been able to adequately solve the problem. This has led to a high rate of small business failures in South Africa. These procurement challenges include late payments, poor contract management, poor cash flow management, the complexity of regulations, too much competition, political interference, and a lack of skills in pricing techniques, to mention a few. This study aimed to appraise the procurement challenges facing emerging contractors in public sector projects in South Africa with a view to developing strategies to mitigate the challenges experienced. The study focused on CIDB-registered construction companies in Gauteng province under CIDB levels 4 and 5 registered as general building and civil engineering classified contractors. The study adhered to a quantitative explanatory approach. A survey questionnaire comprising structured questions relating to the study’s objectives was drawn up and distributed to the participants. The data is presented using the tables while the analysis of the data was achieved through using the appropriate descriptive and inferential statistics to measure characteristics of the study population and to make inferences about the population from data set respectively. The study found that late payments, political interference, poorly managed cash flows, too much competition, and a lack of understanding of pricing techniques were the top five critical challenges facing the emerging contractors in the South African construction industry. Further investigation on the impacts of the identified challenges facing the emerging contractors in South Africa revealed that project cost and time overruns, lack of access to public sector contractors, loss of profits, blacklisting by creditors, liquidation, and abandoned projects negatively impact the success of the emerging contractors in South Africa. The study further identified potential measures to overcome the identified procurement challenges. These measures include: reviewing procurement policies for contractor development with emphasis on business and management skills development programmes; access to finance be made easily accessible; contractors be trained to separate business operations from family operations, including proper cash flow management; skills development training specifically for small contractors; joint venture partnerships for emerging contractors to curb financial and administrative burdens and skills transfer; implementing early payment arrangements with the organs of state and ensuring timely payments from clients; breaking down bids into smaller projects; the provision of more and detailed information for bids during the tender stage; the relaxation of unnecessary bureaucratic procedures; the provision of tax holidays; and after care and follow-up training to be provided to ensure that the small contractors remain in business. Based on these findings, impacts, and mitigation measures, the study recommends revising government policies regarding the payment of emerging contractors to address the challenge of late payments, thus prioritising timely payments for all emerging contractors and, where possible, establishing early payment arrangements; the training of emerging contractors and skills development be prioritised; and entry-level training for CIDB Level/Grade 1 contractors be implemented to upskill those emerging contractors.
Architectural considerations and resource allocation in energy efficient networking
(2022-09-29) Molefe, Mlungisi; Nleya, Bakhe
Word-wide data traffic is continuously surging, triggered mainly by the emergence of Internet-of-Things (IoT)’s services and Fog-Cloud computing-based applications. This calls for existing optical and wireless-based network infrastructures to upgrade capacity accordingly to meet required massive bandwidth demands to accommodate the ever-surging data traffic volumes. However, continuously elevating the resource requirements in terms of bandwidth provisioning implies increasing the number of en-ergy-consuming network elements, which will increase overall operational expendi-tures and carbon footprint due to extra power generation. Carbon emissions contribute significantly to global warming. To avert this, it has become necessary to promote en-ergy-efficient networking. For that reason, it necessitated an emphasis on energy effi-ciency in the design, operation, and planning of transport networks. The current dense wavelength division multiplexing (DWDM) based optical transport network architectures operate with fixed-grid employing fixed data rates. So, making this rigid approach to capacity allocation leads to inefficiencies in both spectrum allo-cation and energy usage. Flexible (or elastic) optical transport networks with flexible-grid were proposed to improve bandwidth provisioning efficiencies. Such networks support adaptive line rates and OFDM-based optical transmission, thus, this will lead to lesser network elements deployed and, consequently an improvement in energy ef-ficiency. Similarly, wireless networks, whose data traffic is mostly derived from de-vice-to-device (D2D) communication and heterogeneous 5G cellular networks (HET-NETs) have since made tremendous strides to further enhance bandwidth by way of overlaying multiple types of low power small cells in a high-power macro cell. They afford more opportunities to explore the potential cognition and cooperation diversi-ties to improve spectral efficiency. Thus in this work, we focus on both architectural design and operation of wireless and optical transport networks coupled with resource allocation. A model joint all photonic and wireless transport network architecture framework is proposed and analyzed. The architecture’s performance in servicing high-capacity mobile back-haul and front-haul traffic and real-time services support is evaluated by both analytical and simulation approaches. Various routing and switching scenarios are considered. Overall, results demonstrate that elasticity allocation of resources (bandwidth) can vastly improve the network performance in terms of spectral efficiency, reduced locking probability, and enhanced end-to-end network throughput.
An assessment of the adoption of smart building concept in the Nigerian construction industry
(2022-05-13) Ejidike, Cyril Chinonso; Mewomo, M. C.
Technological penetration across developing countries has impacted the construction industry, with more construction stakeholders deploying various technologies into the building lifecycle's design, construction, management, and maintenance. The building sector has evolved by adopting and implementing smart tools for its operations over the past few years. Building information modelling (BIM), the internet of things (IoT), and smart devices (sensors) are game-changers that have helped to reduce the complexity of construction activity and increase productivity. Meanwhile, introducing the sustainable development concept in the construction industry has enabled the proper management of the earth's natural resources and provided a pathway for ecosystem balance alongside socio-economic development. Amid the skyrocketing population growth, urban sprawl, and globalization, the building industry is confronted with the challenge of providing adequate and holistic built infrastructures such as efficient energy management, good water supply, occupants' indoor comfort, and the management of construction waste. The smart building concept (SBCs), which employs sustainable construction whereby the built product is constructed according to best practices, including efficient energy use, the recycling of raw material, and the realization of a sustainable and carbon-free environment, has demonstrated the digitalization of sustainable development in the construction industry. Therefore, this dissertation seeks to asseeement of the adoption of smart building concepts in the Nigerian construction industry. The research poses the following questions: 1) What is the awareness level of construction professionals in the adoption of the smart building concept (SBCs) in the Nigerian construction industry? 2) What factors can enhance the awareness of the smart building concept among construction professionals in the Nigerian construction industry? 3) What factors enhance the adoption of SBCs among professionals in the Nigerian construction industry? 4) What are barriers to adopting SBCs in construction projects in the Nigerian construction industry? A random sampling technique in selecting the construction professionals. The total population of construction professionals within the study area is 5,108, comprising construction professionals of Architects, Builders (Mechanical, Electrical, and Structural), Engineers, and Quantity Surveyors practicing in Lagos state. The sample size selection was made using the Yamane formula (1967) for calculating sample size. Therefore, the sample for this study is 363. A well-structured questionnaire of 363 was administered to construction professionals to gather relevant data on the topic. The data collected were analyzed using the Kruskal Wallis H test and weighted mean, factor analysis, and binary regression analysis, and mean item score and agreement analysis technique. The key finding of the research indicated that construction professionals are generally aware of the smart building concept. Administration, education, organizational, and environmental factors were discovered to enhance the adoption of smart building concepts among construction professionals. Furthermore, the research indicates that energy and cost-saving, job creation, safety and security, and health care are the critical factors enhancing in adoption of smart building concepts among construction professionals in the Nigerian construction industry. Lastly, the research result discovered that the high cost of smart building materials, inadequate power supply, resistance to change from the use of traditional technology, poor maintenance culture, poor knowledge of smart building technology, inadequate well-trained labour in the practice of smart building construction, and inadequate finance schemes are the significant barriers to the adoption of smart building concept. Based on this research finding, the research recommends that construction professionals engage more in smart building concepts, propagating the country's awareness and development of smart building construction. Furthermore, the government should establish a common platform for the collaboration of all stakeholders, such as professionals in the construction industry and academia, by way of policymaking and funding of research and development towards implementing these smart technologies. It will go a long way for employment creation and improve the country's economy. This study contributes to the body of knowledge by discovering the critical factors that will aid the successful adoption of the smart building concept in the Nigerian construction industry.
An assessment of the impact of selected construction materials on the life cycle energy performance and thermal comfort in buildings
(2021) Haripersad, Rajesh; Lazarus, Ian Joseph; Singh, Ramkishore; Aiyetan, Olatunji Ayodeji
South Africa is a developing country with various construction projects that are being undertaken both by government and the private sector. The requirements for the construction of energy-efficient buildings as well as the selection methods for providing construction materials have hence become important. Energy efficiency improvements needs to be implemented in the construction of these buildings in order to decrease energy usage and costs and provide more comfortable conditions for its occupants. Previous studies revealed that most of the focus for improving energy efficiency in buildings has been on their operational emissions. It is estimated that about 30% of all energy consumed throughout the lifetime of a building is utilized as embodied energy (this percentage varies based on factors such as age of building, climate and materials). In the past this percentage was much lower, but with increased emphasis placed on reducing operational emissions (such as energy efficiency improvements in heating and cooling systems), the embodied energy contribution has become more significant. Hence, it is important to employ a life-cycle carbon framework in analysing the carbon emissions in buildings. The study aims to augment energy efficiency initiatives by showcasing energy reduction strategies for buildings. The study assessed the thermal performance of selected construction materials by analysing different buildings using energy modelling program, EnergyPlus and TRNSYS. The parametric study was set in the central plateau region of South Africa and was performed to determine appropriate energy efficiency improvements that can be implemented for maximum savings. A life cycle cost analysis was performed on the selected improvements. The models created are representative of the actual buildings when simulated data is compared to recorded data from these buildings. Results showed a significant variation in energy and construction costs with varying construction materials over the buildings’ life cycle. Findings suggest that there is a significant reduction in energy usage when simple efficiency measures are implemented. The study recommends the use of different energy efficient building materials and the implementation of passive interventions in the constructing of buildings; the thermal performance of a building be optimized to ensure thermal comfort and the developed model be adopted for use in the engineering and construction industry for the reduction of energy consumption.
Bioremediation of acid mine drainage and crude contaminated soils
(2020-09) Anekwe, Ifeanyi Michael; Isa, Yusuf Makarﬁ
Pollution is one of the greatest ills plaguing the existence of the ecosystem which could lead to the annihilation of terrestrial and aquatic habitat if not remedied. Acid mine drainage (AMD) and crude oil are among the major land and water pollutants cause by industrial and human activities. The constant exploration, mining, and processing of mineral resources and prevalent use of petroleum products for economic purposes have contributed to contamination of soil and proximate water bodies which results in environmental degradation; thus, remediation becomes necessary. The treatment of AMD contaminated soils using the conventional methods has some room for improvement to meet the remediation purpose. Bioremediation technology provides a sustainable and eco-friendly approach to the treatment of contaminants. This study aims to evaluate the performance of different potential bioremediation techniques and conduct a comparative analysis of these methods for the treatment of AMD and crude oil-contaminated soils. The treatment approach for both pollutants comprises of soils separately contaminated with AMD and crude oil before the application of bioremediation techniques. For the biostimulation study, contaminated soils were amended with varying ratios of the brewery or municipal wastewaters (BWW and MWW), while the bioventing (BVT) treatment involved wastewater amendment and supply of atmospheric air from the vadose zone at 3L/min at 30 minutes intervals every 48 hours. The bacteria strain Pseudomonas aeruginosa ATCC 15442 used for the study which was inoculated at 5%(w/w) was cultured in two different media for respective treatments and wastewater was amended as an extra energy source for bioaugmentation (BAU) study while Bioattenuation (BAT) which received no amendment was used as a control treatment for the study. The treatments were conducted in plastic bioreactors under mesophilic conditions for 28 days and samples were collected from each treatment system on weekly basis to analyse for sulfate, heavy metals, and total petroleum hydrocarbon (TPH) reduction. The result of the study showed that the amendment of contaminated soils with wastewater increased alkalinity in the system which enhanced microbial activities for effective remediation which recorded 52.43 and 51.23% average TPH and metal removal efficiency for the BSTc treatment. Also, the combined application of bioremediation techniques was more effective than single application as the introduction of oxygen into the treatment system with wastewater amendment increased the TPH and metal removal efficiency by an average of 12.98 and 13.17% respectively but efforts to enhance sulfate removal by air-injection (BVTa) proved abortive with 17.20 and 14.67% removal efficiencies less than BSTa and BAUa respectively as sulfate-reducing bacteria thrive in an anaerobic environment. However, P. aeruginosa ATCC 15442 adopts the sorption process in the reduction of hydrocarbon and metal toxicity with 42.02 and 41.81% average removal efficiencies respectively and the amendment extra nutrient (wastewater) increased the removal efficiency of these pollutants by 25.24 and 16.23% respectively. The results of the study inferred that wastewater (BWW and MWW), air-injection and P. aeruginosa ATCC 15442 showed great potentials in the degradation and removal of TPH, metals and sulfate contaminants, hence, can serve as a viable strategy for the remediation of AMD and crude oil polluted soils while improving waste management and amelioration of pollution aftermath faced by communities involved in mining and oil production and/or processing. There is a need for optimization to ensure effective remediation while further study is required to validate large scale application.
Biosorption of Fe2+ from potable water using natural and modified sugarcane bagasse
(2023-05) Ndebele, Nompumelelo Lindi Gelsiah
Even though some metals are crucial for the health and development of human bodies, their presence in higher concentrations is worrisome because it has a detrimental effect on people's health. These heavy metals cause cancer and cannot be broken down by biological processes. The removal of heavy metals from water using traditional techniques; such as reverse osmosis, precipitation, ion exchange; has been the subject of extensive investigation. However, because these processes are so expensive to run, a lot of research is currently focusing on using agricultural biomasses to remove these heavy metals. Dumping of this agricultural waste (sugarcane bagasse) in landfills creates dangers of spontaneous combustion, because of microbial activities. The functionality of circular economy depends on waste resources being utilized to their fullest potential, with almost no production of recoverable waste. In a circular economy, sugarcane bagasse is utilized as a fuel source for the boilers that generate process steam and electricity in the sugar mill facilities. Sugarcane bagasse is used in the manufacturing of paper and paper goods, as well as in the agricultural sector. Stakeholders across the value chain, from product design to waste management, This study fulfils the functionality of the circular economy where it looks at extracting the valuable components of the sugarcane bagasse, then further using the sugarcane bagasse to remove heavy metals from potable water. In this study, the adsorption capacities of unmodified and modified sugarcane bagasse for removing Fe2+ from potable water were investigated in batch experiment studies. Sugarcane bagasse comprises cellulose, hemicellulose and lignin. In order to determine the effect of removing/ extracting each component from the sugarcane bagasse, sugarcane bagasse was pretreated with different concentrations of sodium hydroxide and sulphuric acid, ranging between 0.5 wt% and 2.5 wt%, predominantly used to extract lignin and hemicellulose. A cellulosic structure was left behind after the simultaneous removal of both amorphous components (the lignin and the hemicellulose) using the combined pretreatments of sodium hydroxide and sulfuric acid. The advantages of extracting or eliminating these components came from their high value in many sectors. Lignin is used in the paper business and costs between R11 300 and R17 420 per ton, hemicellulose is used in the pharmaceutical sector and costs between R500 and R1000 per ton, and cellulose is utilized in the textile sector. The concentrations of all chemical pretreatments used on the sugarcane bagasse ranged from 0.5 to 2.5%, with alkaline pretreatments intended to extract lignin, acid pretreatments intended to extract hemicellulose, and combination pretreatments intended to remove both lignin and hemicellulose. While cellulose content increased from 32.02 to 65.65% after sodium hydroxide pretreatment, lignin and hemicellulose content reduced from 22.30 and 24.30% to 7.56% and 13.63%, respectively. Lignin and hemicellulose concentration for the sulphuric acid pretreatment went from 22.30 and 24.30% to 14.90% and 13.63%, respectively, while cellulose content went from 35.02 to 65.65%. After the sugarcane bagasse underwent chemical pretreatments, batch studies were conducted on both the natural and chemically pretreated sugarcane bagasse in order to determine how the removal of lignin, hemicellulose, and cellulose affected the performance of the biosorbents in the biosorption of Fe2+ from drinkable water. To assess the efficacy of natural and modified sugarcane bagasse on the Fe2+ removal, the operational parameters investigated in the batch experiments were initial concentration ranging from 1 to 30 mg/L; pH ranging from 2 to 7, contact time ranging from 5 -100 minutes, and adsorbent dose ranging from 0.2 to 1.4 g. For every variation investigation, one variable was varied at a time while keeping the other variables constant. The experimental runs done were repeated thrice and average values are reported throughout the study. According to the biosorption results, 1% NaOH was the best performing biosorbent for the alkali-pretreatment. The most effective biosorbent for the acidpretreatment variation was 2.5% H2SO4. The optimal combination for the pretreatment was (0.5% NaOH + 0.5% H2SO4). Regarding initial concentration variations, all biosorbents were most effective at a concentration of 1 mg/L, where natural sugarcane bagasse was able to remove 50% of Fe2+, 1% NaOH was able to remove 99.7% Fe2+, 2.5% H2SO4 removed 75.93% Fe2+, and the combined-pretreated biosorbent of (0.5% NaOH + 0.5% H2SO4) removed 87.17% Fe2+ . The increase in biosorbent dose led to an increase efficiency of the natural and chemically pretreated biosorbents. The highest removal of Fe2+ was obtained at 1 g (both for the natural and for all the pretreated biosorbents), with 32.2% for the natural; 79.04% for the 1% NaOH; 58.79% for the 2.5% H2SO4 and 70.73% for (0.5% NaOH + 0.5% H2SO4). Results of the study also showed that the highest removal of Fe2+ for the pH variation of 2-7 was at pH “6” for both the natural and pretreated biosorbents. For the variation of the agitation speed, the highest Fe2+ removal was at 160 rpm with 52% Fe2+ removal for the natural sugarcane bagasse. The Langmuir and Freundlich adsorption isotherms were used to study the biosorption mechanisms. Good correlation coefficients (R 2 ) of > 0.95 were obtained for both the Langmuir and Freundlich isotherms for both the natural and modified sugarcane bagasse, indicating that the biosorption followed both homogeneous and heterogeneity interaction between Fe2+ ions and active functional groups of the surface and pores of the biosorbents. Biosorption results for the natural sugarcane bagasse best fitted with the Langmuir isotherm with qmax of 0.770 mg/g, R 2 of 0.987 and RL of 0.938. The alkali and acid-pretreated biosorbents favoured both the Langmuir and Freundlich isotherms with R 2 > 0.95; RL < 1 and 1 𝑛 < 1. The highest qmax of 9.199 and 5.743 mg/g was obtained at 1% NaOH and 2.5% H2SO4, respectively. The combined pretreatment fitted best with only the Langmuir isotherm with R 2 of 0.987, the R 2 of the Freundlich isotherm was less than 0.9. The biosorption of Fe2+ followed both the pseudo-first-order and pseudo-second-order kinetic reactions with 𝑞𝑒(𝑒𝑥𝑝) in close proximity to 𝑞𝑒(𝑐𝑎𝑙𝑐) and R 2 > 0.9. These results showed that sugarcane bagasse had great adsorption capacity after removing the valued components, namely, lignin and hemicellulose. Characterization studies, which included FTIR, XRD, BET and SEM, were also carried out on the natural and pretreated bagasse before and after adsorption experiments. FTIR confirmed the existence of carbonyl, hydroxyl and carboxyl functional groups as major groups responsible for the adsorption of Fe2+ onto the natural and pretreated sugarcane bagasse. XRD revealed that the natural structure of the sugarcane bagasse was of native cellulose consisting of both amorphous and crystalline regions; this structure became more crystalline after the chemical pretreatments as the crystallinity index increased from 39.04% to 66.85% at 1% NaOH; 57.47% at 2.5% H2SO4; and 57.92% at (0.5% NaOH + 0.5%H2SO4). The natural sugarcane bagasse structure featured rough surfaces, according to SEM data, and the main constituents were silicon (Si), carbon (C), and oxygen (O). According to the BET data, employing 1% NaOH, 2.5% H2SO4, and (0.5% NaOH + 0.5% H2SO4), respectively, the initial surface area of 0.904 cm3 /g rose to 1.503, 1.233, and 1.376 cm3 /g and the pore size of 56.33 ̊A increased to 99.63, 93.680, and 99.10 ̊A. According to the EDS data, sodium hydroxide pretreatment performed better in terms of adsorption, followed by combined pretreatment and sulphuric acid. The natural sugarcane bagasse, 1% NaOH, 2.5% H2SO4, and (0.5% NaOH + 0.5% H2SO4) were able to biosorb 0.77, 7.89, 1.63, and 3.8% Fe2+, respectively.
Characterisation of concrete with expanded polystyrene, eggshell powder and non-potable water : a case study
(2023-05) Mncwango, Bonke; Allopi, Dhiren
Urbanisation has brought many benefits but it has also highlighted the global lack of housing alongside global natural resource scarcity. Lack of housing on the surface appears to be a singular problem, however in reality it represents a number of society’s biggest challenges such as crime, pollution (as a result of inadequate waste disposal strategies), unhygienic living conditions, as well as numerous health problems. Governments across the world have made various attempts at addressing the issue of lack of housing, including embarking on large scale social and public housing initiatives, building smaller homes for the homeless, as well as removing certain regulatory barriers to allow more houses to be built at a reduced timeframe. These advances have assisted many individuals and families globally, however, there are still many individuals and families that government housing-aid or housing initiatives have not yet reached. These individuals and families are faced with solving their housing crisis on their own, with their own resources. Globally, concrete remains a supreme building material in the construction industry and therefore is a primary factor of consideration for solving the housing crisis, especially for those who have no financial assistance or aid from government. Concrete’s composition is simple: cement, fine aggregate, coarse aggregate and water. The intricate interaction between all four components is meant to stand the test of time. Unfortunately, it is not only the earth’s diminishing natural resource reserves which are causing a decline in the popularity of conventionally produced concrete, but it is also the irreparable harm that it is causing to the environment. The process of concrete production requires large volumes of cement, and cement remains one of the biggest producers of carbon dioxide. Carbon dioxide is a greenhouse gas which in excessive amounts creates a cover that traps the sun’s heat energy in the atmosphere. Another major criticism of conventional concrete is the requirement that it be produced with clean water which is of a drinkable standard. This criticism is justified when considering the extreme water shortages that are experienced by many low to middle income countries around the world. The amount of financial and human resources that local authorities invest in cleansing water to bring it to a drinkable standard is often overlooked. It is obvious that it is less expensive to use water directly from a river in its natural state than using it after it has undergone numerous cleansing processes by local authorities. There have been a notable number of advances in making concrete more resource-efficient and environmentally friendly. These include the advent of lightweight concretes such as expanded polystyrene concrete. Expanded polystyrene concrete not only saves the amount of aggregate that would normally be required in conventional concrete, it also has excellent acoustic and thermal properties, thereby reducing energy consumption which in turn saves money. However, even with such excellent properties, expanded polystyrene concrete still fails to address two of concrete’s major criticisms which are related to the amount of cement used as well as the amount of clean potable water required for mixing. Therefore, by building on the qualities of expanded polystyrene concrete, this research investigates the potential of lowering the amount of cement required in a concrete mix through the use of eggshell powder. Eggshells are a waste product found everywhere in the world and are readily available in almost limitless quantities. The use of eggshells in concrete to lower the amount of cement required will not only achieve a reduction in the amount of carbon dioxide that is produced in the process of producing concrete, it will also assist in contributing toward solving the escalating waste disposal crisis that currently exists for many waste types such as eggshells. It is common for communities to reside close to a river or a natural flowing watercourse, so this research included river water as a variable. Four different concrete mix scenarios were tested to ascertain through experimentation whether the strength properties of concrete that contains expanded polystyrene, eggshell powder and natural river water in various proportions could in any way compare to a conventionally produced concrete mix. In order to comprehensively study material behaviour in this case, sieve analysis, bulk density, fineness modulus, moisture content as well as specific gravity tests were performed on all aggregates used. Furthermore, in order to achieve the required analytical depth for the materials being studied, x-ray diffraction and energy dispersive spectroscopy tests were conducted. As a means of conducting further trend analysis on the different experimental mixes, logarithmic regression models were developed. Through analysis of the output attained from the aforementioned strategies, this research study found that when cement was substituted by eggshell powder at a percentage of 5 % and simultaneously when coarse aggregate was also substituted by expanded polystyrene at a percentage of 5 %, all mixed with non-potable water, the compressive and flexural strength outcomes marginally differed from the strength outcomes of conventionally produced concrete. Furthermore, the substitution of stone by EPS at a percentage of 10 % when mixed with river water was comparable to the substitution of stone by EPS at a percentage of 10 % when mixed with potable water. The results showed that there was a difference of not more than 1.4 MPa and 0.3 MPa in compressive and flexural strength respectively amongst the averages obtained at each age tested. Study results show that the substitution of potable water by non-potable water reduced both the compressive and flexural strength of the concrete when the mix did not contain eggshell powder. However, when eggshell powder was included in the mix, the strength outcomes of the compressive and flexural strength of the concrete mix was comparable to that of conventionally produced concrete. There may be many reasons why it is important to not deviate from convention in the production of numerous products such as concrete; nevertheless, the value of experimentation as demonstrated in this research is that experimentation can give rise to a variety of innovations accompanied by a wealth of solutions to the environmental and socio-economic issues that the world is currently faced with.
Collaborative approaches in achieving sustainable private-public transportation services in inner-city areas : a case of the Durban minibus taxis
(2022-05-13) Mabandla, Lonna S.; Musvoto, Godfrey Gombana; Moodley, Sogendren M.
Transportation is a catalytic feature within cities and is interdependent on land use activity by means of a feedback loop that is created between the two. The most catalytic example of this is public transportation routes internal to inner-cities: they draw focus to these areas by enhancing accessibility, therefore creating spaces that are conducive for business activity, while business activity also informs public transportation routes. It is for this reason that this dissertation focuses on public transportation within inner-city areas. Durban is the chosen case study where the dominating form of public transportation within the central business district (CBD) is minibus taxis. The paradox here is that minibus taxis still form part of the informal economy even though they are the leading form of public transportation in South Africa. There have been many attempts to formalise this industry in order for it to follow more regulatory practices, but minibus taxis are privately owned and operate within the capitalist economy. The interventions put in place were aimed to better integrate minibus taxis into the urban fabric of cities for the purpose of creating a more harmonious urban environment, but to date all attempts have failed to produce the intended outcome. This research explores ways in which public and private institutions can collaborate for the intention of creating a better public service. This is critical given that an informal economic entity is dominating the public spaces of South Africa. This research is inspired by the notion of the just city which has major sway in contemporary urban thinking. A just city embraces principles such as good access and heterogeneity in public spaces, amongst others, which are hugely influenced by transportation. The argument of this study is that the application of collaborative planning through a sustainable partnership between the public and private sector will improve the social and environmental sustainability of public transportation. This process is complicated however and one of the major challenges that exist within such collaborative endeavours are power dynamics. As a result, a key focus in the study is around power relations. Practically, power relations should be observed over a period of time, specifically when the different stakeholders engage with each other, so as to reflect valid data. However, a length data collection process was not possible to observe during the data collection phase of this research. Instead interviews were conducted focusing on existing procedural planning practices between the inner-city minibus taxi association (South and North Beach Taxi Association), the eThekwini Transport Authority(ETA), and the eThekwini Town Planning Department. Conclusions and recommendations were then generated based on these data
Comparative analysis of the implementation of Toyota Production System between a tier-one and tier-two supplier
(2024-05) Govender, Prenisha; Dewa, Mendon
The Toyota Production systems (TPS) is a methodology that is widely used in the manufacturing automotive industry. The Toyota pyramid model consists of four levels which can be dissected into the first level of philosophy, the second level named process, the third pillar of people and partners, and lastly the problem-solving level. These are also characterised by 14 principles of the model. However, many suppliers face challenges in implementing these principles from the Toyota pyramid model due to lack of knowledge, understanding or available framework for easy implementation and guidance. This study aims to conduct a comparative analysis of the level of implementation of the 14 principles of the Toyota pyramid model by a tier-one and tiertwo supplier. This study also identified areas of strengths and weakness and made provisions for continuous improvement initiatives at each supplier for future work. A quantitative research methodology with a questionnaire as the research instrument, was adopted for this study. A 5-point Likert type scale was used to elicit responses from 25 research participants from the tier-one and tier-two suppliers. Data analysis was conducted through descriptive values of the means, skewness and kurtosis, and an independent sample t-test was used as an inferential tool to establish the relationship between the tier-one and tier-two supplier. Value stream mapping was also deployed to identify the current production processes and kaizen bursts that characterized the two organisations. The results from the comparative analysis of the level of implementation of the Toyota pyramid model revealed that tier-one supplier was demonstrating better performance than tier-two supplier in the implementation of the 14 principles. In addition, the results demonstrated that principle 1, from the philosophy level had a higher mean or was stronger for each supplier. On the hand, principle 8 and principle 12 were found to be weaker in each supplier respectively. The areas of improvement which were highlighted in the kaizen bursts on the value stream map were addressed and kaizen implementation was undertaken. These improvement initiatives included rebalancing a seat-cover assembly line and deployment of an andon management system at the tier-one supplier to improve line efficiency and line management. A framework was also proposed for the tier-two supplier to bridge the gap in its practice for implementation of the Toyota pyramid model principles. Additional principles were added to this framework to ensure an easier and understandable methodology and framework to be referred to for suppliers and companies to improve.
Comparison for raw and commercial castor oil in the production of biodiesel
(2024-05) Masango, Sandile Brendon; Ngema, Peterson Thokozani; Olangunju, Olusegun Ayodeji; Ramsuroop, Suresh
The development of industries is associated with higher pollution levels and higher fuel costs. The research on clean energy helps to lessen the reliance on fossil fuels, the ozone layer’s depletion, and the release of hazardous pollutants. The development of renewable energy sources increases energy independence and lessens the harm that fossil fuels do to the environment in the Republic of South Africa (RSA), one of the African Nations. The main the challenge is the fragility of crude oil prices, high unemployment, worries about climate change, and the requirement for the continent's developing economies to use their resources sustainably are what motivate the establishment of a successful biodiesel (Fatty Acid Methyl Ester) business. Particularly in recent years, biodiesel has evolved into one of the most popular biofuels for fuel substitution with biodiesel. In this study, homogeneous alkaline transesterification was used to produce methyl ester biodiesel (FAME) from refined or commercial castor oil (CCO) and raw castor oil (RCO) feedstock. The obtained results were compared to those evaluated, which produce better yield by varying essential parameters, which include reaction temperature, catalyst concentration, and alcohol: oil molar ratio at a constant period of 90 minutes. The effect of potassium hydroxide (KOH) as a catalyst between raw and refined castor oil was compared. The result revealed the performance of the KOH catalyst on raw castor oil yields 98.49% FAME, which was higher than the refined castor, oil which yield was 97.9% FAME. The optimal conditions was reaction temperature 45 oC, methanol:oil mole ratio 1:9, and catalyst concentration 0.625 % w/w, were obtained from refined castor oil were applied to raw castor oil because of the same properties. It was found that the yield of raw castor oil was 98.49% which is higher to that of refined castor oil which is 97.9%. General Rate Equation, Pseudo first order model, Second order model, and Modified-Second order model are the kinetics models that were evaluated and discussed. The kinetic models behavior is that the rate of reaction r increase with the increase in temperature, at the maximum reaction temperature of the study 343.15 K, 5.1×10-07 (K.mL/mol.min) General Rate Equation, 5.7×10-08 (K.mL/mol.min) Pseudo first order, 6.9×10-07 (K.mL/mol.min) Second order model, and 61.4×10-04(K.mL/mol.min) Modified-Second order model. Pseudo first order model and Second order model were the best fitted kinetic models then PFO shows to be best kinetic model for the study by measuring absolute error 1.4×10-04 and relative error 0.999 was very low. The methodology adopted for the study include fuel quality of castor oil (raw and commercial) and produced biodiesel were tested for physicochemical properties. Physicochemical properties and ASTM standard.for raw castor oil :- kinematic viscosity 1.98 (cSt) @50 oC, ASTM D445 , Ash 0.03 (g), ASTM D874, Flash point 114 oC, ASTM D93, sulphur 0.64 ppm, ASTM D5453, density 920 kg/m3 , ASTM D1298/0452, water content 0.05 %, ASTM D2709, and calorific value 44121kJ/kg, ASTM D6751, while for commercial castor oil:- kinematic viscosity 2.98 (cSt) @50 oC, ASTM D445, Ash 0.05 (g), ASTM D874, Flash point 116 oC ASTM D93, sulphur 0.65 ppm, ASTM D5453, density 960 kg/m3 , ASTM D1298/0452, water content 0.04 %, ASTM D2709, and calorific value 44121kJ/kg ASTM D6751. The study is also assessed for economic feasibility to determine if it will be profitable. The process design comprises the main processing unit, reactor, separator, mixing tank, centrifugal pumps and heat exchangers. In this study only, reactor was simulated using ASPEN Plus version 11 software utilizing the generated data from the laboratory. Economic feasibility was based mostly on the reactor and scaling up to plant scale. The cost of biodiesel production per year is R 205391.34/ year, sales cost is R 2464696.08/ year which gives a profit of R 1117077.48/ year which proves economic feasibility of the study. It was concluded that raw castor oil can be suitable used in the process of producing biodiesel since it exhibit higher yield. It was recommended that one must use the generated data to up-scale the process and design other unit in details. Asides vegetable oils, castor seeds are among the identified raw materials from which raw castor oil can be extracted for biodiesel production because it has high oil content up to 60%
Designing a stormwaterharvest system in new smart cities in KwaZulu-Natal, South Africa
(2024-05) Mukome, Bwija
The nexus between climate change and water management represents one of the contemporary challenges confronting economic development and sustainable livelihoods in many cities the world over. Thus, assessing the impacts of climate change for evolving smart-city water management, especially for a country like South Africa that is classified as a “water-stressed” country, constitutes an innovative way to water management. This study aimed at proposing an alternative water supply augmentation source that is sustainable for new smart cities under different climatic scenarios within the KwaZulu-Natal Province of South Africa. The specific objectives of the study were to assess the impacts of climate change and the imperativeness of a sustainable and efficient stormwaterharvesting (SWH) system in the new smart city; determine the social, economic and technical barriers to an efficient SWH system; evaluate the technical and financial feasibility of stormwaterharvesting system integration in smart cities; and design a prototype sustainable and efficient pilot-scale engineering SWH system. To address these objectives, the aggregated views of stakeholders within the Water/ Climate change sector were solicited through questionnaires and interviews collected data were analysed using a statistical package and thematic classification. The triangulation method was used to justify acceptable opinions where both the qualitative and quantitative responses were in opposing positions. The standardised rainfall anomaly index (SRAI), simple precipitation ratio (SR), coefficient of variation in rainfall distribution (CV), precipitation concentration index (PCI), and the seasonal precipitation index (SPI) were used to evaluate the impacts of climate change on rainfall variability; whilst different inferential statistics techniques like Mann Kendal, Sen slope, regression, correlations, multifactor analysis (MFA), and chi-square test values- interpreted using the p-values- were used to identify the abrupt changes, trend patterns and significant impacts of climate change on the hydrological water balance for the study area, which in turn influenced decision-making in designing a new smart city. Based on a monthly water balance evaluation, the technical and financial feasibility of stormwater harvest system integration in smart cities was thematically deduced from survey interviews conducted and validated with simple component costing for SWH design and operation. The design of a sustainable and efficient pilot-scale engineering SWH system was synthesised through an extensive literature review for future adaptation. The various analyses and results in ranking the socio-economic and technical barriers to SWH system integration into smart cities connotes ageing infrastructure; the lack of proactive maintenance; and a lack of finance as the biggest challenges to efficient stormwaterharvesting system implementation. The study concludes that SWH presents a viable alternate source for water that might improve urban water self-sufficiency sustainability under different climatic smart city assessments, whilst recommending capacity development where climate change experts transfer knowledge, skills and expertise to upcoming researchers.
Development and evaluation of woven fabric immersed membrane bioreactor for treatment of domestic waste water for re-use
(2014) Cele, Mxolisi Norman; Rathilal, Sudesh; Pillay, Visvanathan Lingamurti
Increased public concern over health and the environment, the need to expand existing wastewater treatment plants due to population increase, and increasingly stringent discharge requirements, have created a need for new innovative technologies that can generate high quality effluent at affordable cost for primary and secondary re-use. The membrane biological reactor (MBR) process is one of the innovative technologies that warrant consideration as a treatment alternative where high quality effluent and/or footprint limitations are a prime consideration. MBR processes have been applied for the treatment of industrial effluent for over ten years (Harrhoff, 1990). In this process, ultrafiltration or microfiltration membranes separate the treated water from the mixed liquor, replacing the secondary settling tanks of the conventional activated sludge process. Historically, energy costs associated with pumping the treated water through the membranes have limited widespread application for the treatment of high volumes of municipal wastewater. However, recent advancements and developments in membrane technology have led to reduced process energy costs and induced wider application for municipal wastewater treatment (Stephenson et al., 2000). This report describes a small and pilot scale demonstration study conducted to test a woven fabric microfiltration immersed membrane bioreactor (WFM-IMBR) process for use in domestic wastewater treatment. The study was conducted at Durban Metro Southern Wastewater Treatment Works, Veolia Plant, South Africa. The main objective of this project was to develop and evaluate the performance of an aerobic woven fabric microfiltration immersed membrane bioreactor (WFM-IMBR) for small scale domestic wastewater treatment. The experiments were oriented towards three sub objectives: to develop the membrane pack for immersed membrane bioreactor based on WF microfilters; to evaluate the hydrodynamics of WF membrane pack for bioreactor applications; and to evaluate the long-term performance and stability of WFM-IMBR in domestic waste water treatment. The literature was reviewed on membrane pack design for established commercial IMBR. The data collected from literature was then screened and used to design the WF membrane pack. Critical flux was used as the instrument to measure the WF membrane pack hydrodynamics. Long-term operation of the WFM-IMBR was in two folds: evaluating the performance and long term stability of WFM-IMBR. The membrane pack of 20 flat sheet rectangular modules (0.56 m by 0.355 m) was developed with the gap of 5 mm between the modules. The effects of parameters such as mixed liquor suspended solids or aeration on critical flux were examined. It was observed that the critical flux decreased with the increase of sludge concentration and it could be enhanced by improving the aeration intensity as expected and in agreement with the literature. Hence the operating point for long term subcritical operation was selected to be at a critical flux of 30 LMH and 7.5 L/min/module of aeration. Prior to the long term subcritical flux of WFM-IMBR, the operating point was chosen based on the hydrodynamic study of the WF membrane pack. The pilot scale WFM-IMBR demonstrated over a period of 30 days that it can operate for a prolonged period without a need for cleaning. Under subcritical operation, it was observed that there was no rise in TMP over the entire period of experimentation. Theoretically this was expected but it was never investigated before. Good permeate quality was achieved with 95% COD removal and 100% MLSS removal. The permeate turbidity was found to be less than 1 NTU and it decreased with an increase in time and eventually stabilized over a prolonged time. Woven fibre membranes have demonstrated great potential in wastewater treatment resulting in excellent COD and MLSS removal; low permeate turbidity and long term stability operation. From the literature surveyed, this is the first study which investigated the use of WF membranes in IMBRs. The study found that the small scale WFM-IMBR unit can be employed in fifty equivalence person and generate effluent that is free of suspended solids, having high levels of solid rejection and has acceptable discharge COD for recycle. Future work should be conducted on energy reduction strategies that can be implemented in WFM-IMBR for wastewater treatment since high energy requirements have been reported by commercial IMBRs.
Development of a hybrid fuzzy-mathematical cleaner production evaluation tool for surface finishing
(2007) Telukdarie, Arnesh
The metal finishing industry has been rated among the most polluting industries worldwide. This industry has traditionally been responsible for the release of heavy metals such as chrome, nickel, tin, copper etc into the environment. The application of cleaner production systems to a range of industries, including the metal finishing industry has provided significant financial and environmental benefits. An example of a successful application cleaner production in the metal finishing industry is the reduction in the typical water consumption from 400 1/m² to less than 10 1/m² of plated product. The successful application of cleaner production to the mental finishing industry has encountered many barriers. These barriers include the need for a highly skilled cleaner production auditor and the need for rigorous plant data to effectively quantify the cleaner production potential of the company under consideration. This study focuses on providing an alternate user-friendly audit system for the implementation of cleaner production in the mental finishing industry. The audit system proposed eliminates the need for the need for both a technical auditor and rigid plant data. The proposed system functions solely on plant operator inputs. The operator’s knowledge is harnessed and used to conduct an efficient and effective cleaner production audit. The research is based on expert knowledge, which was gained by conducting audits on some 25 companies using traditional auditing tools. This company audits were used to construct a database of data that was used in the verification of the models developed in this study. The audit is separated into different focus components. The first system developed was based on fuzzy logic multi variable decision-making. For this system the plant was categorized into different sections and appropriate fuzzy ratings were allocated based on experience. Once the allocations were completed multi variable decision analysis was used to determine the individual variable impact. The output was compared and regressed to the database equivalent. Operator inputs can then be used to determine the individual category outputs for the cleaner for the production rating for the company under consideration. The second part of this study entails the development of mathematical models for the quantification of chemical and water consumptions. This was based on the present and ideal (cleaner production) plant configuration. Cleaner production operations are compared to present operations and potential savings quantified. Mathematical models were developed based on pilot scale experiments for the acid, degreaser and zinc plating process. The pilot experiments were carried out on a PLC controlled pilot plant. These models were developed form factorial experimentation on the variables of each of the plating processes. The models developed aid in the prediction of the relevant optimum consumptions. The key challenge in traditional evaluation systems has been the quantification of the plant production. The most effective measure of production is by means of the surface area plated. In this study a novel approach using the modeled acid consumption is proposed. It was assumed that the operator inputs for the above models would not be precise. The models developed allowed for input variations. These variations were incorporated into the model using the Monte Carlo technique. The entire cleaner production evaluation system proposed is based on an operator questionnaire, which is completed in visual basic. The mathematical model was incorporated into the visual basic model. For the purpose of model verification the mathematical models were programmed and tested using the engineering mathematical software, Mat Lab. The combined fuzzy logic and mathematical models prove to be a highly effective means of completing the cleaner production evaluation in minimal time and with minimal resources. A comparative case study was conducted at a local metal finishing company. The case study compares the input requirements and outputs from the traditional systems with the system proposed in this study. The traditional model requires 245 inputs whilst the model proposed in this study is based on 56 inputs. The data requirements for the model proposed in this study is obtained from a plant operator in less than one hour whilst previous models required high level expertise over a period of up to two weeks. The quality of outputs from the model proposed is found to be very comparable to previous models. The model is actually found to be superior to previous models with regards predicting operational variations, water usages, chemical usages and bath chemical evolution. The research has highlighted the potential to apply fuzzy-mathematical hybrid systems for cleaner production evaluation. The two limitations of the research were found to be the usage of a linear experimental design for model development and the availability of Mat Lab software for future application. These issues can be addressed as future work. It is recommended that a non-linear model be developed for the individual processes so as to obtain more detailed process models.
Development of an Intelligent Standalone Solar Photovoltaic 48V DC microgrid system
(2024-05) Makhanya, Thandeka; Pillay, N; Sewsunker, R
With load shedding negatively affecting South Africans there are many concerns regarding stable power delivery to residential households. Amid all the power delivery concerns some rural communities are still not connected to the existing power infrastructure. Implementation of newer efficient clean energy sources is in demand. A standalone Photovoltaic (PV) Solar distributed renewable energy Direct Current (DC) microgrid can be the best possible approach to tackle the power grid shortcomings and to electrify communities that are not yet covered by the power grid or communities that want to transition to clean energy. The research focuses on the design of an optimal 48 VDC Multiple-PV Standalone microgrid in remote areas not covered by the main grid. The proposed microgrid can be typically used for lighting, charging phones, and other low-power applications. The microgrid will consist of 4 microgrid subgrids, each consisting of a dedicated Solar PV array, battery storage systems, loads, and other components that connect to the DC Bus and need to be monitored and controlled for efficient operation. Furthermore, the subgrids were designed based on the meteorological data of the selected location and the load demand for each subgrid. The microgrid design enables the subgrids to share power through a bidirectional DC-DC converter based on certain conditions. A power-sharing management system was implemented to manage power-sharing ensuring that the sharing subgrid does not drive its users to load shedding. Moreover, the microgrid design was simulated on Matlab/Simulink to observe the operation of the designed system and to determine if the proposed design would be able to achieve the desired goal. The results obtained from simulations indicate that the proposed microgrid design can provide an optimal service to its users by allowing the subgrid with surplus energy to share its power with the subgrid when needed.
Development of integrated model and framework for sustainable energy resources and systems planning
(2024-05) Akpan, Joseph Samuel; Oludolapo, Olanrewaju Akanni
Sustainable energy development (SED) is a crucial component of the Sustainable Development Goals (SDG), aiming to maintain economic and social progress while protecting the environment and mitigating climate change's effects. SED serves as a transition paradigm for sustainable development, providing a blueprint for energy peace and prosperity for people and all uses. The first objective of this dissertation is to identify 10 interlinked themes of SED and explore 2 of them, which are the least studied in existing SED reviews. These two themes include energy financing and commitment to climate change and the need for 100% renewable energy (RE), a part of the decarbonization strategy towards the 1.5 - 2.0 °C Scenario. The study suggests that the current G20 countries' contributions, if done continuously per annum, in addition to 80% more funding from private investment of the same amount in the 1.5°C scenario financial requirement for clean energy, is sufficient to limit global warming. In addition to the present drive for 100% RE for all purposes, an emphasis is placed on addressing other issues, such as energy storage options, developing countries' development agenda, and regional security stability to prevent energy wars. Emerging SED decarbonization strategies are presented across power, transport, building, and industrial sectors. This part concludes with a summary of SED progress and directions for future research, mainly the need for re-defining Nationally Determined Contribution (NDC) through a centralized global or regional stock-taking strategy for greenhouse gas emissions reduction. Consequently, the next study attempts to address the limitations of the current NDC by formulating a policy hypothesis and applying it to an integrated assessment tool (here, termed the environmental model) for strategic stock-taking in reducing GHG emissions. In developing this indexing model, being the first objective of this thesis, we analysed the potential impact of Nationally Determined Contributions (NDCs) under the Paris Agreement on global temperature rise used as the key model input parameters with countries' historical data and other parameters such as GDP, population growth. With the use of an integrated assessment tool based on the concept of system dynamics, the analysis constructs a framework to project global temperature changes under five policy scenarios, namely baseline, current (announced energy policies 1 and 2), and optimum (2.0 0 C Scenario), and most optimum (1.5 0 C) case scenarios. The hypothesis is formulated based on the analysis of current, announced, and best-case global and or applicable national policy scenarios. The model aims to address critical questions regarding the effectiveness of the on-going NDCs commitments in limiting global temperature rise to well below 2 0 C, in alignment with the Paris Agreement's goals. The simulation results offer a roadmap for optimizing the current NDCs in global and national energy policies and treaties, fostering international collaboration, and reinforcing the global commitment to combating climate change. Leveraging on the preceding simulation result of the environmental model, a novel emissions budgeting (EB) model tool (here, termed the economic model) was introduced as a simplified approach for the determination of the economic attractiveness of the policy scenarios of the environmental model. Hence, the second objective, which was to determine the economic benefit of policy scenarios, was achieved. Some advanced countries’ rapid population, economic growth, and energy consumption from mostly 100% electricity that is majorly fossil-based contributes significantly to global CO 2 emissions. In contrast, the case in most developing countries is different. For instance, electricity access in Africa is less than 60%. Hence, this presents challenges and opportunities for achieving the United Nations’ Sustainable Development Goals (SDGs) 7 and 13 of generating all energy from cleaner or low-carbon sources to reduce CO 2 emissions in all countries and combating climate change consequences. Therefore, considering the peculiar situation of other developmental goals, such as increasing population access to electricity while being obliged with the need to transit to complete renewable energy, as our third objective, we explored the idea and transition paradigm of reaching a 100% renewable energy that is void of unjust energy transitioning, climate injustice, and unbiased drive for increasing renewables energy penetration in the global energy mix. The increasing need for renewable energies has been widely acknowledged to greatly advance the climate change agenda as increasing clean energy usage depletes the accumulation of GHG in the atmosphere. Alongside reducing the accumulation of GHG, increasing RE share in the national mix has constantly become the core of many countries' energy policies and the agenda of many of the NDCs reported by countries. Presently, about 30 countries already with over 70% of their national electricity mix from RE. A part of this has birthed a new paradigm and an emerging field of 100% RE for all purposes, recently receiving much attention from academia and in public discourse. Upon establishing the need for analysing the transition towards 100% RE, the thesis demonstrated this conceptual idea through a model (here, termed the energy model) to analyse the possibilities for a 100% renewable energy system at the global level. Because several studies have already done such analysis, however, this has hardly been directly linked to the climate scenarios. Therefore, this thesis bridged this gap in the literature by synthesising the energy transition at different percentage shares in the global primary energy mix over time with the effect on global temperature levels. The rationale behind this was to present a discussion on the pathway possibilities and challenges of achieving 100% RE and whether it is possible to meet the total global energy demand through RE, with what effect on the climate scenarios. To do this analysis, we further define our hypothesis using baseline, optimum, more optimum, and extreme optimum path scenarios to ascertain such possibilities. Finally, we used an integrated assessment model based on the principles of system dynamics to analyse these hypotheses and to find the implications of each action or scenario on other factors such as global temperature, GHG emissions, energy storage breakthrough while keeping the population growth at maximum possible value of 12.4 billion persons by 2100 with GDP growth rate not less than 1.5%. The findings are valuable in helping us discuss if 100% RE can be a reality and what the implications are. Our results show that in the baseline current scenarios, the global average temperature will most likely be kept at 3.3 0 C. Hence, the world would need very urgent and unprecedented efforts beyond the current baseline of business as usual. Interestingly, our findings also indicate that to stay within the 1.5 and 2.0 0 C Scenarios, the world may need just between (58.6 - 77.3) % and (62.7 - 82.8) %, respectively, in the global energy mix. For the most optimistic scenario, (75.5 - 99.8) % RE may be required, and this is able to keep the temperature rise even well below 1.5 0 C but at 1.1 0 C. The 1.1 0 C possibility is quite highly ambitious, in my opinion, because it requires the intensity of global mix energy generation of about 6627 extra joules from renewables only. The major challenge with the idea of 100% RE for all purposes is that achieving such a feat requires a more diverse approach and scarcely are there 100% RE studies that incorporate holistically the interrelation of several pertinent strategies. Therefore, there exists a need to meet both the technical and non-technical requirements. In order to address this shortcoming, our third objective introduces six methodological or evaluation mechanisms (herein, identified as 100% RE evaluation metrics) suitable for existing and future 100% renewable energy analysis. It then reviews energy modelling tools to identify their applicability to 100% RE analysis. The perspectives presented in this thesis are valuable in developing a common integrated methodology and modelling tool for analysing full renewable energy adoption in countries or regions with best trade-offs, using performance indices that have not been previously used. The proposed metrics could also help with proper national and regional energy resources and system planning for new energy projects and installations, contributing to sustainable development. The framework and narrative, presented in the form of a model within this dissertation, make a noteworthy contribution to the ongoing discourse surrounding the energy transition as, to the best of my knowledge, this concept has not been presented this way. The results from this dissertation can be further investigated through a streamlined application of the approach at individual country or regional level to facilitate inclusive and climate-responsive planning and execution strategies for sustainable energy and electricity generation, distribution, and utilization at both national and urban levels. The implications of the findings have the potential to inform the United Nations Framework on Climate Change Convention (UNFCCC) and Conference of Parties (COP) policies in better ways of promoting equitable support for countries, regions, energy consumers, utilities, and prosumers.
Development of multi-objective optimization model for project portfolio selection using a hybrid method
(2024-05) Mogbojuri, Akinlo Olorunju; Olanrewaju, Oludolapo Akanni
Selecting inappropriate projects and project portfolios can result in irreversible wasted economic opportunities, reduced manpower value, and missed prospects and other resources for the organization. As a result, to achieve the best possible outcome, all criteria to enable the best possible choices to be made should be considered. Choosing projects wisely and managing the project portfolio can assist organizations in gaining a better understanding of their projects and their risks and advantages. When faced with budget and other constraints, the ability to select an optimal mix of projects is a significant advantage in the project selection process. The selection of projects by means of employing an effective method is uncommon because many methods are deemed ineffective due to limitations on the number of projects that can be chosen, along with the failure to select economical projects. Project selection is a complex, multicriteria decision-making procedure involving numerous and frequently competing goals. The complexities of project selection problems stem primarily from the large number of projects that are required to be selected for an appropriate collection of investment projects. The study identified some research gaps such as limited studies on social sustainability benefits, criteria for public project selection not being considered or mentioned, and the decision-making committee or expert generating weight to the deviational variables instead of using weighting techniques. The aim of this study is to employ an integrated approach to establish a multi-objective optimization approach for public project portfolio selection. The specific research objectives are to develop an integrated method of Analytic Hierarchy Process, Goal Programming and Genetic Algorithm (AHP-GP-GA), establish a relationship for the developed models to correct the bias of each model and apply the integrated method in a selected community with a set of projects. Data was collected by compiling a well-structured questionnaire for decision-makers analysed by applying the AHP and GP methods. The composition of the integrated approach includes decision support tool with exact and includes meta-heuristic modelling known as Analytic Hierarchy Process, Goal Programming and Genetic Algorithms (AHP-GP-GA) for solving public project portfolio selection problems. The Analytic Hierarchy Process model was used to develop project selection criteria, assign relative priority weights of decision makers, and determine the overall weight of project alternatives. The GP constructed the mathematical model to handle large numbers of objectives and constraints. The GA is the solution algorithm for the effective and flexible optimization model to produce optimal solutions. The AHP and GA employed Spice Logic and MATLAB software packages to analyse, validate and enhance the research. The AHP model highlighted some sub-criteria and project criteria attributes that are significant to project selection criteria. These criteria are economic development, job creation, community acceptance, structure aligned with company goals, employment record of project manager, locality of the project, finish period of the project selected, project threats and political impact. Meanwhile, empirical research on public agencies was undertaken with the AHP-GP-GA, AHP-GP and GP separately to address the problem. The GP and AHP-GP used the LINGO 18.0 software package, while the developed integrated method AHP-GP-GA was solved using MATLAB software package to exhibit the competence of the model and the research. The high point of the empirical research showed that the AHP-GP-GA model can solve large-scale, or complex problems with a large number of decision variables. It selected more projects compared to the AHP-GP and GP standalone model and provided more optimal solutions, which made the approach robust and flexible for solving decision-making problems. The theoretical and practical contributions of the study are the research, which will improve the knowledge and understanding of researchers or academia in PPSP and add to the literature to enhance the existing methods of integrated approaches. The stakeholders in project management practitioners like organization management, top executives, senior and junior supervisors, and personnel connected to the projects will also benefit from the research in selecting optimal projects from the various solution options, saving costs, and learning how to handle and select more complex projects in large-scale real-life situations. This study recommends further research on the integration of stochastic models, evolutionary algorithms, or computation with AHP and GP for the Public Project Portfolio Selection Problem.
The effect of heavy metal composition on the performance of sugarcane bagasse as an adsorbant in water treatment
(2021-04) Buthelezi, Nokulunga Priscilla; Isa, Yusuf Makarﬁ
Wastewater produced by the industries is potentially harmful to the ecosystem because of various contaminants like heavy metals that find their way into soil and water supplies. Industrial waste constitutes different kinds of metal which contaminate natural water. Heavy metals can build up in the environment and enter living organisms through chain elements such as the food chain and therefore, pose a major health risk to living organisms. The situation has been worsened by the absence of broadly accepted heavy metal treatment techniques, thus this challenge continues to receive considerable attention from stakeholders including scientists and researchers. While many technologies have been proposed such as reverse osmosis, flocculation, ion exchange and so on and so forth, they continue to suffer from a number of drawbacks including generation of secondary wastes and cost ineffectiveness. Thus, in the present study, adsorption was chosen as a cost effective, efficient, and environmentally friendly treatment process. Sugar cane milling production produces a lot of sugar cane bagasse which is considered as environmental waste if not disposed properly. It is imperative to remove heavy metals from polluted water before discharging it into the environment, rivers and lakes using sustainable techniques. Heavy metal removal from wastewater using low-cost adsorbents like sugarcane bagasse addresses two problems: removal of pollutants from water and utilization of agricultural waste. This study evaluated the performance of sugarcane bagasse in the removal of heavy metals. Sugarcane bagasse was characterized to determine the functional groups, the porosity and surface area, crystallinity and morphology using FTIR, SEM and XRD. One factor at a time (OFAT) approach was used to evaluate the effect of operating parameters on the removal of heavy metal ions. A 3-system component of the stock solution of synthesized wastewater namely single, binary and ternary were studied. The 3 metal ions evaluated were Copper, Chromium and Cadmium. The factors considered in the OFAT design of experiments were contact time (30-240 mins), adsorbent dosage (5-30g/L), initial concentration (50-500 mg/L), pH(2-9), and particle size (75-600 μm). It was observed that all adsorption parameters had an effect on the adsorption rate. However, an adsorption dosage had a greater impact on the adsorption rate. An increase in the adsorption dosage from (5-20 g) showed that the percentage removal efficiency for chromium, copper and cadmium increased from (40-72%, 44-75% and 39-59%) in a single metal system. In addition, the percentage removal increased from (34-62% for chromium, 47- 78% for copper, and 34-62% for cadmium) in a binary metal system. Furthermore, the percentage removal increased from (38-52%, 40-59% and 24-43%) for chromium, copper, and cadmium in a ternary metal system. Adsorption capacity of the adsorbent was determined using the optimal operating parameters obtained from the OFAT design of experiments. Langmuir and Freundlich isotherms were used to analyze the adsorption data. The OFAT design of experiments resulted in producing the optimum conditions for adsorption. The optimum conditions for maximum adsorption were, contact time (180 mins), initial concentration (50 mg/L), pH (7), dosage (20 g), particle size (340-450 μm) and a mixing speed of 150 rpm. Adsorption capacities differed between the 3 system components. Maximum adsorption capacities of 38.41 mg/L were registered for copper ions and was recorded for the single component system. Stock solutions containing copper ions registered the highest adsorption capacity. There was a significant decrease in the maximum adsorption capacities for copper ions of the binary and ternary system components which were 21.45 mg/L and 1.237 mg/L respectively. This was attributed to the co-metal ion dependence in both the binary and ternary system components. In conclusion, the study showed that sugarcane bagasse can be used as an adsorbent in the efficient removal of heavy metal ions present in wastewater.