Theses and dissertations (Engineering and Built Environment)

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Adoption of intelligent transport systems for sustainable transportation in secondary cities of South Africa : a case of Port Shepstone
(2019-08) Madihlaba, Goodness Lerato; Musvoto, Godfrey Gombana
Transportation is one of the major phenomenon which often directs population increase, investments and land use patterns in cities. Most cities, particularly secondary cities often do not entirely plan for future transportation when planning for massive investment developments thus leaving such cities with transportation challenges which include aging transport infrastructure, increased traffic patterns, insufficient parking spaces, high-accidents rates, to name a few. The most ignored transportation solution in secondary cities is the use of technology to manage transportation challenges in which such solutions may include the establishment of Intelligent Transport Systems (ITS). This research study seeks to examine what are the possibilities of using ITS to address the transportation challenges of the secondary city of Port Shepstone, what are the recommendations that can be put forward for establishment of ITS in Port Shepstone. In an attempt to discover these questions, the study conducts a literature review analysis which outlines what others have done in this research area and progressively attempts to provide recommendations on the possible establishment of ITS solutions in Port Shepstone. The literature review focuses on five (5) functional areas (i.e. Advanced Traveller Information Systems (ATIS); Advanced Transportation Management Systems (ATMS); Advanced Public Transport Systems (APTS); Enabled Transportation Pricing System (ETPS) and Data Acquisition Management Systems (DAMS)) which their possibility of being established in the secondary city of Port Shepstone is investigated The literature review analysis is supplemented by semi-structured interviews with various stakeholders within the transportation sector; and their views are constructively analysed to draw converging findings. The empirical findings from both literature review analysis and conducted interviews provide meaningful answers to the research questions and enabled the researcher to draw fundamental recommendations and possible ITS solutions to address the transportation challenges of Port Shepstone.
Anaerobic co-digestion with industrial wastewater for biomethane production
(2020-10-20) Adedeji, Jeremiah; Chetty, Maggie
The increasing demand for energy has led to the utilization of fossil fuels more abundantly as a quick alternative for generation of energy. The use of these sources of energy however as led to the generation of greenhouse gases which tend to cause climate change, thus affecting the ecosystem at large. Thus, there have been the search for alternative sources which cannot be depleted but do generate minimal greenhouse gases. One of such alternate sources is industrial wastewater which have shown to have high concentration of nutrients in the form of organic contents which can be converted by micro-organisms into energy, usually known as biogas, comprising majorly of CH4, CO2 and H2. Another important factor is that industrial wastewaters are a renewable energy source which are continuously generated due to increasing urbanisation and population growth. In this study, the characteristics of three agro-industrial based wastewaters used shows their potential for application in anaerobic co-digestion”. Anaerobic co-digestion method was utilized to harness the synergetic effect of both sewage sludge and agro-industrial wastewater as co-substrate for the generation of biomethane. The result of the effect of varying mix-ratio of the substrates on biomethane production of sugar wastewater and dairy wastewater indicated that mix-ratio of 1:1 for sewage sludge to sugar wastewater operated at 35oC was suitable for optimum generation of biomethane of 1400.99 mL CH4/g COD added and COD reduction of 54%. The model generated using design expert was found to navigate the design space and could perfectly predict the yield of biomethane effectively for the sugar wastewater mix. The biomethane potential tests (BMP) experiment using varying inoculum-substrate ratio (ISR) showed that operating at mesophilic temperature of 25oC with ISR of 1:2 and 2:1 for sugar wastewater and dairy wastewater respectively does increase the methane production within the first three (3) weeks. The kinetic models that best fit the anaerobic co-digestion for sugar wastewater was the first order model while the simplified Gompertz model favoured the dairy wastewater perfectly. The biomethane potential tests indicate significant increase the biomethane production and as well reduction in the volatile solid and chemical oxygen demand (COD) content. In conclusion, both sugar and dairy wastewater can be recommended as co-substrates for anaerobic digestion of sewage sludge for increased and improved biomethane production while simultaneously reducing their COD content at the same time.
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.
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.
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
Crash modeling of a light composite aircraft
(2014) Moletsane, Moeletsi Augustinus; Jonson, David
ABSTRACT The study presented here was focused on the crash analysis of light composite aircraft on relatively survivable accidents. The crash analysis approach was based on the numerical simulation using the finite element software (MSC.Dytran). The aircraft crash environment, impact terrain, impact angles and material properties were identified, and later introduced into the aircraft crash model. The background on composite materials is discussed and more focus was given to their response at high strain rates. The modeling methodology is also discussed with more emphasis on the finite element analysis approach and the failure theories behind composite materials. The failure criteria are based on assumptions considered for the classical lamination theory, and each of the failure theories in MSC.Dytran were evaluated before being introduced into the crash model. The Tsai-Wu failure criterion was found to be capable of predicting the progressive ply failure of the composite lamina. The Ravin 500 light composite aircraft model was used for the purpose of this study and four crash scenarios of impacting the aircraft onto the soil model were considered. The aircraft was impacted at the same crash velocity but different flight path angles were considered. The 10⁰, 15⁰, 20⁰ and 30⁰ crash angles together with a crash velocity of 22m/s were used. The impact approach was influenced by the previous literature; it shows that the structural damage of an aircraft during crash accident is affected largely by the crash angle. The results of each crash scenario are presented and mainly focused on the failure response of the aircraft structure. The conclusion on the crashworthiness of the Ravin 500 light composite aircraft is also drawn based on the numerical work. Details regarding the future work or recommendations for the design philosophy and means of improving the crashworthiness of the light composite aircraft are also presented. In addition, more emphasis is focused in the occupant’s space within the aircraft.
A critical analysis of participation using the planning context of the Durban Back of Port Precinct
(2023-05) Ngubane, Sibongiseni Memory; Hansmann, Robynne; Musvoto, Godfrey
Communities located in the Durban Back of Port area experience the compounded burden of environmental degradation with the legacy of untransformed Apartheid neighbourhoods. Despite the documented concerns and priority to deal with the cumulative environmental impacts on the communities of South Durban within planning policy documents, the participation process is unclear. Poorly defined participation processes not only inhibit the substantial issues being raised but fail to inform processes to address the concerns raised. These weakly defined civic engagements were found in the study to reflect some of the implementation challenges in the field of urban planning. The primary aim of the research study is to critically analyse participation processes for development as outlined in planning policy documents to make proposals within the context of the Durban Back of Port case study from sampled stakeholder categories; corporate community, civil society, and government. The Durban Back of Port case study is a geographical area under the authority of eThekwini Municipality in KwaZulu Natal. This precinct represents a situation where communities live near one of Sub-Saharan Africa’s busiest industrial areas, and at the backside area of one of the most active ports in Africa. This research study found the precinct residents to have been subjected to both environmental racism, and post-Apartheid environmental injustice. The study area presents contrasting land uses, where negative externalities of industrial development impact on the adjacent residential uses. In effect, the legacy of Apartheid spatial planning is layered with environmental racism and has evolved into environmental injustice in present time. This is a qualitative research study that applies hybrid analytical tools; document analysis, policy analysis and thematic analysis to critically analysis participation processes within the case study. This research study established three type categories of stakeholders representing varying interest; economic, social, and environmental. The purposely sampled categories comprised of corporate community, civil society, and the spheres of government, these are organisations that are either located or have jurisdictional authority in the Durban Back of Port. It uses the theoretical lenses of Environmental Justice, Advocacy Planning, Communicative Rationality and Action, Collaborative Planning, Participatory Planning, and Arnstein’s Ladder of Participation to better understand participation processes.
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.
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.
Energy-efficient resource management framework for cloud data centers
(2023-05) Sibiya, Khulekani; Nleya, Bakhe
The continuing global surge in various cloud services, IoT, and Edge (Fog) computing has led to a sudden increase in the demand for Datacenters. By definition, a data center is a physical facility that corporations/organizations use to house their critical applications and data. A data canter‟s design is based on a network of computing and storage resources that enable the delivery of shared applications and data. Notable advantages of Data Centers include but are not limited, to their ability to provide services to end-users based on affordable rates in various plans as per contractual agreements. They also offer a robust hardware ecosystem as well as software. In operational terms, data centers offer reliable and enhanced system performance by way of carefully distributing the traffic loads uniformly across the cluster nodes. In that way, end users are excused from maintenance responsibilities. Data centers also afford instant scalability based on changing capacity demands by users. To enhance the fail-safe abilities of data canters, backup systems are incorporated. A notable drawback of Datacenters is the high power consumption which up both CAPEX and OPEX costs. E.g it is prohibitively costly to erect robust cooling systems for a large-scale data center. The same cooling system ought to be scalable to accommodate future expansions of the data centers in terms of new services that may require new hardware to be incorporated. Thus scalability of energy supply capacity is quite a challenge. Thus, how to maximize power utilization and optimizing the performance per power budget is critical for data centers to deliver enough computation ability. Overall the operational costs of Data centers directly link the resource management algorithms implemented to assign virtual machines (VMs) to actual hardware servers and degrees of flexibility to relocate them elsewhere in case of emergencies usually associated with power losses of excessive heating of system elements. The main contribution of this thesis is in proposing and analyzing a hierarchical SLA-based distributed hierarchical resource allocation and optimization scheme, that considers constraints such as energy consumption and cooling-related energy consumption in addition to the scalability issue. We also incorporate a load-balancing algorithm to minimize the operational costs of the proposed scheme. We utilize CloudSim, which is a customizable tool that supports the modeling, and creation of several VMs, (as well as mapping tasks to appropriate VMs) for the scheme‟s performance evaluation. Ultimately obtained results show that the scheme significantly reduces the operational costs of the overall cloud data center system and at the same time ensures energy efficiency.
Enhanced biohydrogen production from carbohydrate rich wastewater through anaerobic fermentation
(2020-11-30) Mutsvene, Boldwin; Chetty, Maggie; Pillai, S. K. K.; Bux, Faizal
In recent times,“the world has faced serious problems emanating from the use of fossil fuels which are detrimental to the environment at large. On the other hand, due to the industrial boom, many industries produce wastewater that is harmful to the environment hence, carbohydrate-rich industrial wastewater can be advantageously used to reduce impact on the environment. If subjected to anaerobic fermentation, organic wastewater has the potential to produce renewable energy sources that have less impact on the environment, including biohydrogen, which has little or no carbon footprint. While reducing the impact of the problems caused by the disposal of wastewater to the environment, the biological methods also offer a solution to the detrimental effects of fossil fuels and their after use effects. The study was mainly based on environmental protection and clean, renewable alternative energy production by generating biohydrogen from organic industrial wastewater as a substrate. Anaerobic digestion has been extensively studied, but dark fermentation, which is an emerging technology within anaerobic digestion that involves the production of hydrogen from carbohydrate-rich substrates, has less information documented regarding this technology. This technology is crucial in the because it forecasts beyond fossil fuel usage and is accompanied with long-term economic expansion and energy security as there are many reservations about fossil fuel reserves and their high risk of exploitation.” Biohydrogen potential tests (BHP) were performed on five different wastewater streams (yeast, alcohols, brewery, sugar, and dairy industries) to determine the stream with the best hydrogen potential. Rigorous characterisation of various wastewater streams was conducted; the main parameters of interest were COD, BOD, VS, TS, pH, among others. The BHP tests were conducted in triplicates in 600 mL Schott bottles charged independently with various wastewater streams and inoculated by the seed sludge from a local wastewater treatment plant at the different substrate to biomass ratios. The highest hydrogen composition was recorded with the brewery wastewater, which had 40.1% H2 in the off-gas as analysed by the gas chromatograph; and the minimum was found in alcohol wastewater, 21.4%. The Kepner-Tregor decision-making tool was conducted to determine the most suitable stream for the scaled-up reactor. A conclusion to use the brewery wastewater in the scaled-up Anaerobic Baffled Reactor (ABR) was reached. Four 10 L Anaerobic Baffled Reactors were used as the scaled-up reactors to optimise operating conditions for the production of biohydrogen using the brewery wastewater. Design-Expert software, under response surface methodology, was used to produce the matrix of combinations of the experimental runs by varying temperature (32-38℃), batch time (4-16 h), and pH (3.5-7.5); in total 20 runs were formulated.” The highest hydrogen production rate of 18.16 mL/h and the hydrogen yield of 30.98 mmol/gCOD were observed at temperature, batch time, and pH of 35℃, 4-10 h, and 5, respectively. The optimum operating conditions were determined to be a temperature of 36℃, batch time of 10.2 h, and a pH of 5.6. A predictive model, quadratic polynomial in nature, was developed after an intensive analysis of variance, a regression coefficient between predicted and actual hydrogen production rates was found to be 0.92. A system was run on optimum conditions to validate the developed mathematical model. The maximum hydrogen potential rate (HPR) determined in this study was 6.11% higher than the predicted value. The validation runs were also performed as control experiments for comparison between a system with nanoparticles and a system without nanoparticles with regards to the HPR. 25.37% H2 and 21.85% H2 were determined for with magnetite nanoparticle system and a system without nanoparticles, respectively. The experiments with nanoparticles garnered 44% higher HPR (23.41 mL/h) than a system without nanoparticles.
Evaluation and optimisation of biogas production in municipal wastewater treatment plant using computational intelligence approach : potential to generate electricity
(2022-05-13) Ramrathan, Zesha; Enitan, Abimbola Motunrayo; Han, Khin Aung
Development and optimisation of valued added derivatives from wastewater represent the future sustainability paradigm. Among the various challenges in the management of wastewater treatment is the energy consumption for the treatment process that could render this process inefficient in terms of cost and energy consumption. This study focusses on the evaluation of egg-shaped digesters treating municipal wastes, and the optimisation of biogas production using computational intelligence approach (CIA) for sustainable energy production and policy implementation. The study further estimates the amount of electricity that could be generated from the optimised biogas produced from the anaerobic digesters. Historical 5-year (2010-2015) data of the anaerobic digesters were obtained from the Darvill Wastewater Treatment Plant in the KwaZulu-Natal Province of South Africa. The raw data were pre-processed for data cleaning, integration, reduction and data transformations using a rigorous scientific method to test their accuracy, reliability, consistency, and localisation gaps with different multivariate statistical tools. Computation intelligence methods using partial least square (PLS), principal component analysis (PCA) and Fuzzy Logic algorithms were used in this study for simulating the best operational condition and predicting the biogas production. The study further created a contextual framework against the assessment of biogas to energy potential and uses an excel-based tool to determine the bio-economy of energy recovery from an anaerobic egg-shaped digester per cubic meter of treated sludge. In average, the actual methane production was 59.60% while, predicted by Fuzzy-Logic was 65.4%. This shows that the model employed in the improvement of methane production from biogas plants by varying the operational parameters at; Inflow = 590m3 /day, Temp = 32.3°C, pH = 7.12, TS = 3.47%, VS = 43.4% and COD = 510 mg O2/L. The obtained total biogas production was 802.80 m3 /day based on status quo conditions and process configurations. The biogas production translates to electrical energy of 4580.5 KWh/day with an estimated saving (at R1.90 per kWh electricity) of approximately R3.1 million per annum.
Fabrication and analysis of nanoparticle-infused natural fibre honeycomb core in sandwich structures
(2024-05) Govender, Sumeshan; Kanny, Krishnan
his study investigates the feasibility of employing natural fibre materials to fabricate honeycomb core structures, addressing concerns over the environmental impact associated with conventional cores composed of aluminium, Nomex, and petroleum-based materials. The research process involves the fabrication of honeycomb cores utilizing a 3D printed moulding technique, followed by the adhesion of these cores to flax and glass fibre facings, thereby augmenting structural durability. Through the incorporation of cellulose and nanoclay as additives to the adhesive, the investigation reveals a substantial enhancement in flexural strength and impact resistance, surpassing the performance of structures bonded solely with epoxy. However, a notable reduction in compressive strength is observed upon the introduction of these additives to the adhesive. Quantitatively, the study demonstrates that the addition of 3wt% cellulose to the epoxy adhesive results in a remarkable 7.43% increment in flexural strength, a 4.09% increase in yield stress, a 0.17% rise in flexural modulus, a 6.45% enhancement in core shear ultimate strength, a 7.17% increase in facing bending stress, and a 7.94% elevation in absorbed energy. Similarly, the addition of 3wt% nanoclay to the epoxy leads to a significant enhancement, with a 10.48% rise in flexural strength, a 4.09% increase in yield stress, a substantial 20.92% augmentation in flexural modulus, a 10.75% improvement in core shear ultimate strength, a 10.5% increase in facing bending stress, and an elevated absorbed energy by 14.37%. Furthermore, in out-ofplane oriented structures, ultimate compressive strength experiences an increase of 7.32% and 20.1% for cellulose and nanoclay additives, respectively, while compression modulus rises by 6.6% and 29.65%. Nevertheless, it is noteworthy that the structures bonded with nanoclayfilled epoxy exhibit the most favourable overall performance, boasting an ultimate compressive strength of 7.72 MPa and a compression modulus of 7.77 MPa, outperforming their in-plane counterparts due to the larger compressive area of the out-of-plane samples. In terms of tensile properties, the study establishes that hybrid face sheets display an impressive 33.65% higher ultimate tensile strength compared to plain flax fibre samples. Additionally, the hybrid face sheets manifest a 69.45% increase in tensile strength and a substantial 58.73% enhancement in yield stress and Young's modulus, respectively, in contrast to exclusively flax fibre facings. Moreover, the research indicates that hybrid face sheets lead to significantly reduced moisture absorption, with structures employing solely flax fibre face sheets experiencing a mass increase of 11.88% after 168 hours of exposure, while structures utilizing hybrid face sheets encounter a substantially lower mass increase of 6.31%. This corroborates the effectiveness of hybrid face sheets in enhancing the water resistance properties of the composite. In summation, the study underscores the potential of natural fibre honeycomb composite structures to perform comparably to traditional honeycomb materials such as Nomex and aluminium, while being constructed from environmentally sustainable materials. The integration of an efficient additive manufacturing process further bolsters the prospects of these structures, enabling customization and scalability for diverse applications across industries, including aerospace, automotive, and marine sectors.
Geographic information system as a vessel for conventional and alternative forms of zoning
(2020-10-06) Kitching, Joseph; Musvoto, Godfrey Gombana
Given the well-documented rates of global urbanisation and the fact that sub-Saharan Africa is set to urbanise at the highest rate during the next few decades, it is easy to understand that urban management systems will increasingly be under pressure to operate efficiently, effectively and transparently in order to circumvent potential economic, social and environmental disasters. A land-use management system is one of the management systems in urban areas aimed at ensuring health and safety, environmental quality, sustainability, social equity, and amenity, amongst others. Since the beginning of the twentieth-century, a key tool of planners wishing to accomplish this, has been zoning. Although zoning has been abused, and heavily criticised for that, the objectives of zoning systems around the world echo noble values such as promoting environments that are safe from flooding and fire hazards, that encourage harmonious communities and economic growth, that preserve agricultural land, and protect the natural environment. Conventional zoning, which was significantly shaped by the US Supreme court’s village of Euclid decision, focuses on the separation of incongruent land uses. There are also several other types of zoning such a flexible Euclidean zoning, performance- based zoning and even no zoning. Amongst the novel types are form-based codes, which stem from the New Urbanism paradigm. Form-based codes focus more on the public realm and the appearance of spaces and structures rather than the use of space. Practically and problematically, both conventional and alternative zoning schemes are currently comprised of a map and a separate text document. The map depicts the geographic dispersion of zones, typically related to properties or zoning districts. The text document contains regulations pertaining to the various zones, procedures and definitions. Alongside the inefficient separation of regulation and map, are the variations within single zones where specific, locally important, regulations apply to some properties within the zone. Geographic information systems (GIS) have been evolving since the mid-twentieth century and have gained serious traction with the advent of the microcomputer. Defined by many as a system that captures, collects, manages, analyses and presents geographic data and attributes, it is essentially a database linked to a geographic component, In the case of zoning, it currently comprises geographic properties linked to attributes describing the zoning. The rigid, surveyed, property boundaries make the vector or discrete objects model ideal for the representation of zoning. The raster model – the other half of the debate – is useful in representing images supporting the regulations. Given the need for more efficient systems, the pervasiveness of corruption and poor capacity in municipal systems, the omni-present abuse of power, the need for an informed citizenry and laws that are comprehensible, this study aims to see if GIS can be used to represent the regulations in conventional and alternative schemes. To establish this, six sample cities from around the world, more than twenty conventional zones in the eThekwini municipality and two zones from the Daufuskie form-based code were assessed to determine what types of regulations are common and whether they could be represented as either geographic norms or attributes to geographic features. This study found that GIS is able to represent all regulations in conventional schemes and most of the regulations in alternative zoning. It also found that some regulations are naturally inclined to spatial representation, others as attributes, and still others as scanned attachments or hyperlinks. This implies that there is no need for the separation of regulations from property and the confusion and potential misinterpretation that are associated with current practices.
Integrated hydrological modelling for sustainable water allocation planning : Mkomazi Basin, South Africa case study
(2018) Amoo, Taiwo Oseni; Dzwairo, Bloodless; Allopi, Dhiren
Allocation of freshwater resources between societal needs and natural ecological systems is of great concern for water managers. This development has challenged decision-makers regarding how to reasonably allocate available water resources to meet the competing demands. Thus, turning these concerns into opportunities requires the need for both water technology innovation and water behavioural change, in order to manage fresh water in a sustainable manner. This study aimed at investigating the applicability of an integrated hydrological model in a Geographical Information Systems (GIS) environment for sustainable water allocation planning and management, using the Mkomazi Basin in KwaZulu-Natal Province, South Africa, as a case study. Specifically, the study identified ecosystems that depend on Mkomazi River for preservation of their environmental and public benefit values; developed a water allocation mechanism to achieve equitable water distribution and large benefits from water uses across the basin’s users; synthesised rules for sustainable development in sharing the limited water resources and maintaining environmental quality; and finally, established a framework for water trading in order to encourage water use efficiency and allow movement of water to new users. Historical 15-year (1990-2015) observed streamflows and daily meteorological variables (precipitation sums (mm), relative humidity (%), wind speed (m s_1), mean, minimum and maximum air temperature (oC), solar radiation (MJ/m2), sunshine duration (h) and evapotranspiration (mm)) were used for this study. The hydro-meteorological data collected from various sources were subjected to frequency trend analysis, correlation, regression and the double mass curve to test their accuracy, reliability, homogeneity, consistency and localisation gaps. The ombro-thermic diagram was used to classify the months into wet and dry periods. iii The identification of prominent ecosystems that depend on the Mkomazi River was achieved through a comprehensive desktop survey and documentation acquired from the Department of Water and Sanitation (DWS). Multivariate statistical methods; cluster, factor and principal component analysis, were applied to analyse the surface water quality data sets extracted from the repository of South Africa’s water resources website (WR2012), in other assess their impact on the aquatic net benefit values and environmental preservation. A semi-distributed event process and an integrated Soil and Water Assessment Tool (SWAT) model in a GIS environment, with descriptive statistical of mean, median, mode, standard deviation, skewness, and kurtosis were employed to simulate the basin’s hydrological process in evaluating the basin’s water balance. The SWAT model was parameterised, calibrated and validated from corrected hydro-meteorological data from 2004 to 2013. Sequential Uncertainty Fitting Algorithm (SUFI2) was used for the model sensitivity analysis, calibration and validation of the model. Artificial Neural Networks (ANNs), Probability Distribution Functions (PDF), and a Flow Duration Curve (FDC) were used to project future available water. Based on the estimated available water, an estimation of allocable water was made based on percentage dependability of the river yield to the different users. The weilbul ranking was used for choosing the dependable flow; this was subsequently used for the different water riparian’s demand distribution. Large benefits derivation from water uses across the basin’s users was based on priority-driven sustainability. Extensive literature review work was used to synthesise rules for sharing limited water resources and maintaining environmental quality for sustainable development. These rules were all drawn from similar world experiences for efficient and gainful utilisation of water and other natural resources. The synthesised rules and principles were modified to suit iv KwaZulu-Natal Province (KZN) water allocation reform regulations. The established water rules were subsequently adapted to the present (Mkomazi) case study area. The proposed developed water trading framework leans on an inclusive simulation of ‘Hydrology, Environment, Life (aquatics), Policy and Sensitivity’ (HELPS) collective response of the basin in exploring the socio-economic and environmental consequences of water regulation. It uses a System Dynamic (SD) simulation technique to form a composite supply-side augmentation with demand-side improvement system to allow movement of water to new users and encourage water use efficiency. The results of the agglomerative hierarchical cluster analysis grouped the 10 sub-basin sites into three clusters of highly polluted (HP), medium polluted (MP) and relatively less polluted (LP) group basins with latent factors of 81.9, 3.14 and 0.858 (%) in the total water quality variance data sets. The water quality index analysis shows a mild effect on irrigation farming and aquatic species. The results of water balance simulation show that mean monthly values were 28.6 m3/s over the years with Nash-Sutcliffe Efficiency (NSE) values of 0.83 and a coefficient of determination (R²) of 0.77 at validation stage. The Curve Number (CN) is the most sensitive parameter for the estimation of both streamflow and water yield within the catchment. Other water balance simulation ratios include: Streamflow/precipitation (0.4 mm); Baseflow/Total flow (0.67 mm); Surface Runoff/Total flow (0.33 mm); Percolation/precipitation (0.20 mm); Deep recharge/precipitation (0.01 mm) with an Evapotranspiration/precipitation ratio of 0.58 mm respectively. The water allocation results in the different dependable flow rates of 60%, 70%, and 85% reliability revealed it to be 17465.56, 8068.04 and 6373.35 (m3/s) at U1H009 discharge station, respectively. The synthesised literature rules suggest water allocation reform acts should be catalysed v through the institutionalisation of capacity developmental platforms where climate change transformation experts and other stakeholders have input in legislating water reform acts, which should be supported by a strong political will. The invented SD framework confirms agricultural water use as the highest demand when compared with other users. Its sustainability index was evaluated as the ratio of aggregated possible water demand relative to the corresponding supply in the same period. The result shows an integrated scenario which combines rainfall variation with improved irrigation water use efficiency and gives the optimal sustainability performance index (0.25) of the system at 70% dependable flow. The simulated water balance results also reveal the use of scientific visualisation techniques in QSWAT to model spatially distributed and time-varying hydrologic-meteorological data sets in evaluating the water balance, while its calibration and validation in SWAT Calibration Uncertainty Procedure (SWAT-CUP) algorithm connotes a strong model efficiency performance. The developed SD framework provides comprehensive assessment methodology for the decision-maker in assessing water trading. The applied integrated model can be used in similar river basins sharing related attributes to the study area in resolving the current water – stressed challenges in South Africa as well as other regions of the globe. Considering the extent of the drought and the paucity of the uneven allocation of water resources at the study area, the needfulness of integrated hydrological models such as SWAT and ANNs cannot be overemphasised in ensuring the sustainability of Mkomazi Basin, while unlocking the untapped potential of water resources for the development of the agricultural and industrial sectors, and still meeting the requirements of the ecosystem.
Integrated life cycle assessment and system dynamics model for prediction of cement production and environmental impact of cement industry
(2023-05) Ige, Oluwafemi Ezekiel; Olanrewaju, Oludolapo Akanni; Duffy, Kevin Jan; Collins, Obiora C.
Cement is one of the most produced materials globally. The cement industry faces significant environmental challenges due to high raw materials usage and energy consumption, resulting in emissions that are global and local environmental concerns. The industry faces challenges globally in reducing its carbon dioxide (CO2) emissions while saving material and energy resources. The cement industry contributes to high global greenhouse gas (GHG) emissions due to the calcination of raw materials and fuel burning. Globally, cement plants are among the sectors with the highest energy consumption and the highest release of potentially harmful health-threatening carbon dioxide (CO2), nitrogen oxides (NOx), sulphur dioxide (SO2), and dust particles. This study focused on Portland cement production and environmental impact-related problems and found the best ways to discuss the potential policies and scenarios to reduce CO2 emissions and ensure sustainable cement production while maintaining the strength of the equipment and the quality of the plant production requirement. Since the cement industry's environmental impacts are expected to increase, assessing the cement production and carbon emissions produced at each stage of the cement life cycle is compulsory to mitigate these environmental impacts. Life cycle assessment (LCA) has been used in many studies to assess the environmental impact of cement production and investigate ways to improve environmental performance. In this thesis, the first step uses life cycle impact assessment (LCIA) based on the Recipe 2016 v 1.04 midpoint and endpoint methods to investigate the environmental impact of 1 kg of Portland cement produced in South Africa using Ecoinvent database v3.7.1, integrated with SimaPro 9.1.1. software to assess the impact categories. The study was conducted using data modelled from South African cement plants and uses a cradle-to-gate system boundary. The integration method includes data collected between 2000 and 2017 on cement production and real GDP. Data on cement production were obtained from the South African greenhouse gas inventory report of 2017. The data on South Africa’s real GDP in US dollars were obtained from World Economics. The LCA-SD framework of cement production in South Africa involves three main stages, (i) gathering data for key LCA processes, (ii) assessing the impacts of production processes using LCA SimaPro 9.1.1 software and (iii) integrating the results of the LCIA as input variables with system dynamics (SD) to predict the possible future dynamic and long-term environmental impact of cement production in South Africa. An integrated LCA-SD methodology is used to assess and predict the environmental impacts of the cement industry. This research uses the LCA method together with the system dynamics framework in the form of a mathematical model to study how to reduce GHGs in cement production. The possible dynamics of cement production and the long-term environmental impact of cement production in South Africa were investigated using these methods. According to the results, clinker production and electricity usage stages contribute the most to atmospheric impact (global warming, which causes climatic change due to high CO2 emissions), followed by raw materials and fuel consumption, contributing to the toxicity and resource depletion impact category. These stages contribute more than 76% of CO2 eq. and 93% of CFC-11 eq. In the midpoint method, CO2 is the most significant pollutant released. Among the three main damage categories in the endpoint method, human health is the most affected by releasing substances into the air during Portland cement production. The clinkering stage is the most harmful production stage for human health and the ecosystem since it produces the highest amounts of CO2 gas. From our projections, the pollutant outputs of cement production in South Africa will approximately double by the year 2040, with the associated long-term impact of an increase in global warming. The proposed LCA-SD model methodology enables us to predict the future dynamics of cement production and its long-term environmental impact, which is the primary research objective. Using these results, several policy changes are suggested for reducing emissions, such as introducing more eco-blended cement production, carbon budgets and carbon tax.
Investigation of potential high-yielding groundwater aquifer zones using remote sensing & GIS technology
(2022-09-29) Moodley, Tyrone; Seyam, Mohammed
Groundwater exploration has been critical in considering groundwater as an alternative freshwater source in basin management. Groundwater exploration simulates the aquifer yield capacity, which is helpful for planning purposes and water resource assessments. However, understanding the dynamic flow conditions of groundwater affected by anthropogenic land cover, water use changes, and uncertain climatic variability, especially in a semi-arid region like South Africa (SA), has called for quantification and quality rating of the resource. The aim of this study was to assess the groundwater potential (GWP) and identify high-yielding groundwater aquifer zones in KwaZulu-Natal (KZN), South Africa. Groundwater potential zones were spatially mapped using Geographic Information Systems (GIS) and remote sensingbased multi-criteria analysis. Spatial thematic layers viz. geology, lineament density, slope, drainage density, rainfall, land use/land cover and evapotranspiration were processed and developed using GIS and weighted using Saaty’s Analytical Hierarchy Process (AHP). The thematic layers were subsequently aggregated using the GIS Weighted Overlay Method to develop a groundwater potential index map. Indices from the map were correlated with data from 113 boreholes using the Receiver Operating Characteristic Curve (ROC) and Area Under the Curve (AUC) to validate the results. Due to the widespread domestic use of groundwater in SA and the minimal available groundwater quality data in KZN, the groundwater quality data for parts of SA were analysed regarding concentrations of pollutants, inorganic chemicals and macropollutants. Groundwater quality data was obtained from available literature across SA and was compared with the South African National Standards (SANS) and World Health Organization’s (WHO) guidelines for drinking-water quality using the weighted arithmetic Water Quality Index (WQI). A Piper Plot was then used to graphically analyse the chemistry of the groundwater samples to compare their ionic compositions. The groundwater quality results revealed that most parameters were below or slightly above the maximum permissible limit, except fluoride, which exceeded the permissible limit in most studied locations and drastically affected the WQI values. The computed WQI values ranged from 37.92 – 436.06. Therefore, of the eleven groundwater data sets, four are classified as “good”, two as “poor”, one as “very poor”, and four as “unfit for drinking”. The results highlight the need to treat fluoride in South African groundwater, as it is a significant factor in categorising areas suitable for groundwater consumption. From the groundwater quality results it was deduced that the water quality data was either clustered as “magnesium-bicarbonate” or “sodium-chloride” type. The results of the groundwater potential mapping revealed that the AHP-based GWP map exhibited a strong correlation with borehole data (r=0.726, n=113), indicating the accuracy of the AHP as a rating method. The results computed that approximately 47.3 km2 (2%) of the total area falls under Excellent GWP, 24405.4 km2 (27.45%) under good GWP, 50950.5 km2 (57.3%) under moderate GWP, and the poor and very poor GWP zones constitute around 13380.8 km2 (15.1%) and 135.6 km2 (1%) of KZN respectively.
Life cycle assessment of the production of cement : a South African case study
(2021-12-01) Olagunju, Busola Dorcas; Olanrewaju, Oludolapo Akanni
The relentless ongoing pursuit of innovation, development, urbanization and immigration for a better quality of life has impacted the natural environment. Also, the various consequences of continuous industrial activities are seen in the departure from what is supposed to be the norms of nature and an ideal environment free of toxicity, pollution and unquantifiable instantaneous changes. One of these is variation in temperature experienced in recent times as against what it was about 2000 years ago before the industrial revolution. A world with an increasing population requires infrastructure to support this growth. The construction industry is able to support this growth by building necessary structures that will accommodate environmental sustainability. However, the construction industry is responsible for several environmental impacts as a result of various activities. Concrete is one of the major base materials used in the construction industry and cement is an essential ingredient in concrete production. Several environmental impacts ranging from high greenhouse gas (GHG) levels to high energy consumption (fossil fuel and electricity) to high resource usage are associated with cement production. Quantifying these impacts is a major roadmap to reducing them. In this study an analysis of the production model of South African cement plants was carried out so as to quantify its impacts, and know how they consequently affect the lives of South Africans, her resources as well as the ecosystem; so that proper mitigation strategies can be recommended. The study carried out a Life cycle assessment (LCA) of cement using both the midpoint and endpoint approaches of the LCIA. LCA is a tool used to analyze the environmental impact of a process or product from start to finish. This study carried out a cradle-to-gate analysis of 1kg of cement produced in a typical South African plant using data from the Ecoinvent database and SimaPro 9.1.1 software. The result showed that for every 1kg of cement produced, O.993 CO2 eq, was emitted into the atmosphere; 98.8% was actual CO2 emission and its resultant effect was global warming which causes changes in climatic conditions. Also, 1.6kg of 1,4-Dichlorobenzene (1,4-DCB) eq was emitted into the air and water, which caused high toxicity in these media and for every 1kg of cement produced, 0.139kg of oil eq was produced and its effect was seen in fossil resources scarcity. Of this value, 0.125kg was from the burning of coal In both approaches, the result was further analyzed with respect to five major production processes: (1) Clinker production (2) Raw material consumption (3) Electricity usage (4) Fuel consumption and (5) Transportation. The results showed that the clinker production stage contributed 76.3% to global warming; and raw material consumption contributed 95.9%, 99.9%, 90.7%, and 77.9% to ionization radiation, mineral scarcity, fossil resource scarcity and terrestrial ecotoxicity, respectively. Fuel consumption contributed 98.6%, 96.3%, 85.7% and 76.9% to freshwater eutrophication, marine eutrophication, human carcinogenic toxicity, and human non-carcinogenic toxicity, respectively. Electricity usage contributed 65.8% and 64.8% to stratospheric ozone depletion and fine particulate matter formation, respectively. Though South Africa relies on the importation of clinker and cement, in the endpoint approach an estimation was carried out based on the annual requirement of cement in South Africa without importing either commodity. The result showed that 55 404 was the potential number of human lives that could be endangered annually; 133 species had the potential to be endangered annually, and the effect of a potential scarcity of resources caused total a marginal price increase of R6.2 billion due to these damages. The results of the analysis are in line with previously published literature but with slight variations. In conclusion, the study prescribed mitigation and adaptation strategies to counter these environmental impacts.
Non-revenue water : most suitable business model for water services authorities in South Africa : Ugu District Municipality
(2016) Mwelase, Lorraine Thulisile; Dzwairo, Bloodless; Adeyemo, Josiah; Otieno, Fredrick Alfred O.
Water is a critical resource in Southern Africa. The region thus needs to protect both the quality and the quantity of its water resources through robust water conservation and demand management (WC/DM) measures. Water demand management encompasses activities that aim to decrease water demand, improve the efficiency of water use and prevent the deterioration of water resources. Water conservation refers to policies, measures or consumer practices that promote the conservation of water resources. Water resources should be used wisely to secure a water supply that is of good quality and enough for South Africa’s people and its natural environment, which provides the ecosystem that supports all forms of life. When a water utility systems experience water losses, the amount of water available to consumers is reduced, making it difficult to satisfy demand. Water losses also occur as a result of inaccuracies in customer meters, data errors in the billing system and unauthorised consumption. Such losses result in non-revenue water (NRW), which is a serious threat to the water supply sector. NRW refers to the water that is produced and lost without generating revenue for the utility. This research study investigated strategies that could be used to address the challenge of water losses, by developing a more suitable business model that could be incorporated into Ugu District Municipality (DM)’s existing NRW reduction strategies. The study was carried out in Amandawe and Umzinto zones of the District Municipality and it covered the period 01 March 2014 to June 2015. The study objectives were made up of four components. The first was to identify and prioritise the implementation of NRW reduction strategies. This was achieved by identifying the pipes to be closed off, which were supplying a significant number of consumers. For those pipes that were not closed off, flow meters were installed to measure the flow into and out of a zone. The system was then tested for zero pressure by isolating all closed valves to ensure that there were no potential feed-backs into the zone. Pressure gauges were set up on standpipes for routine pressure monitoring. The test was run at night (between 01.00 and 05.00 hours) when the system was under pressure. When the pressure dropped consistently, this meant that there was no feedback into a zone. Leaks were detected by logging the system in order to obtain night flows, which were analysed to determine the system behaviour. The results for Amandawe Zone after implementation of the pressure management programme, indicated that the average zone’s night pressure (AZNP) decreased from 7.38 bars to 5.95 bars. For Umzinto Zone, the AZNP dropped from 5.5 bars to 3.3 bars. The minimum night flows (MNFs) dropped from 34.80 m3/hr to 15.20 m3/hr in Amandawe Zone and from 6.4 m3/hr to 1.70 m3/hr in Umzinto Zone. The daily cost of excess night flow due to bursts was reduced from R2276.17/day to R862.61/day in Amandawe Zone and from R361.24/day to R40.46/day in Umzinto Zone, which provided huge savings. The second objective was to identify the sources and causes of water losses in the study area by conducting field measurements and observations. This was achieved by physically inspecting the infrastructure using visual observation, mechanical listening sticks, correlators, ground microphones and system loggers. The following indicators were used to physically identify underground leaks: unusually wet surfaces in landscaped areas, pools of water on the ground surface, noticeably green, soft and mouldy areas surrounded by drier surfaces, a notable drop in water pressure or flow volume, unexplained sudden increase in water demand or water use at a fairly steady rate for several billing cycles, cracks in paved surfaces, potholes or sink holes and the sudden appearance of dirty water in the main distribution system. For this study, the water losses in the system were found to be as a result of various causes including leaks, aging infrastructure, high pressure in the system, damaged pipes and illegal connections, among others. The third objective was to construct a water balance in order to determine the key performance indicators for the NRW reduction strategies. This was achieved by determining the system input volume (SIV), billed authorized consumption (BAC), unbilled metered consumption (UMC), unbilled unmetered consumption (UUC), real losses (RL), apparent losses (AL) and IWA Key Performance Indicators. Bulk and domestic meter readings were used to calculate the components of the water balance. The results of the water balance indicated that there was a decrease in the SIV from 904 kL/day to 523 kL/day in Amandawe Zone and from 382 kL/day to 221 kL/day in Umzinto Zone. The physical water losses were reduced from 611 kL/day to 377 kL/day in Amandawe Zone and from 93.8 kL/day to 45.8 kL/day in Umzinto Zone. The NRW was reduced from 659 kL/day to 395 kL/day in Amandawe Zone and from 94.2 kL/day to 46.2 kL/day in Umzinto Zone. The fourth objective was to develop the most suitable business model for Ugu DM based on the results arising from the first three objectives. Ugu DM needs to ensure both operational and financial efficiency. Operational efficiency could be achieved by minimising real water losses through reviewing water services standards, developing district metering areas, pressure management, leak detection and repair, reservoir control to stop overflows and pipe replacement programs. Financial efficiency could be achieved by carrying out regular meter testing and calibration, securing database integrity, managing illegal connections, ensuring that all customer connections have meters and ensuring that the tariff structures were cost reflective in order for the municipality to cover costs and generate revenue. Findings of this study could assist other water utilities operating under similar conditions. The implementation of this study’s results could have positive economic, social and environmental effects on Ugu DM. It was concluded that rezoning, pressure management and leak detection were the most critical NRW reduction strategies as they had a positive impact on the system. The main causes of leaks in the system were identified as aging infrastructure, high pressures in the system, and illegal connections. All the critical KPIs of IWA water balance responded positively after the implementation of the strategies by reducing. The operational and financial efficiencies were identified as critical for a WSA to develop a business model that could sustain itself.
Optimisation of dissolved air flotation (DAF) for separating industrial mineral oil from water
(2018) Tetteh, Emmanuel Kweinor; Rathilal, Sudesh; Robinson, Kate
Industrial mineral oil wastewater from oil refineries and petrochemical processing poses a major environmental concern. Effluents from these processes is usually poor as it is heavily polluted, thus have high chemical oxygen demand (COD), soap oil and grease (SOG), turbidity, total suspended solids (TSS) amongst others. This wastewater, if discharge without treatment, causes severe pollution, oxygen depletion, and imbalanced ecosystem and human health risks. The main aim of this research was to modify, optimise and evaluate the performance of a continuous process using dissolved air flotation (DAF) pilot to treat wastewater from a local South African oil refinery wastewater treatment plant (WWTP) with the benefit of recovery of the oil from the wastewater. The study evaluated the feasibility of using different acids and coagulants. One factor at time (OFAT) approach was used on the DAF jar tester to identify the most important variables that affects the DAF treatability performance. The factors considered were; pH, flotation time, coagulant dosage, air to water ratio and air saturated pressure. The ranges considered for the factors were pH (4−6), flotation time (5−15 minutes), coagulant dosage (10−50 mg/L), air to water ratio (5–15%) and air saturated pressure (300–500 kPa). The key process operating parameters obtained from the OFAT were optimised using the Box Behnken design (BBD) adapted from response surface methodology (RSM). The BBD used had three levels, three factors and five centre points. This was employed to establish the relationship that existed between the water quality (contaminants) and the key interacting factors of the DAF jar tester, thus employing the most applicable combination of the factors on a continuous DAF pilot plant. The study was configured into two; Acid – Coagulation-DAF (pre-treatment) and Acid –DAF – Coagulation (post treatment). Three acids were investigated for their efficiency in the pre- treatment step, while four cationic inorganic coagulants and three polymeric organic coagulants were used both for the pre and post treatments. The OFAT experiments resulted in more than 75% removal efficiency of COD, SOG, TSS and turbidity. The removal efficiency was obtained at the following optimum values of pH 5, flotation time of 15 minutes at a coagulant dosage of 50 mg/L and an air to water ratio of 10% and finally, air saturated pressure was 350 kPa. On the other hand, BBD results showed 85% treatability performance at a lower coagulant dosage (30–45 mg/L), moderate air saturator pressure (300–425 kPa), and air-water ratio (8–12%) on the batch scale. While on the continuous process, the optimum coagulant dosage was around 100–180 mg/L. From the BBD results, the interacted factors for consideration were the air saturated pressure and coagulant dosage. These factors enhanced process control. The validation of all the response quadratic models were in good standing with the analysis of variance (ANOVA). The experimental results and the predicted models results agreed at 95% confidence level, finally, the models were significant and verified. Comparative studies of the pre and post treatment showed that 1 M H3PO4 was the most effective, economical and environmentally friendly acid to be used for both processes. Two cationic inorganic (alum and ferric chloride) and two polymeric organic (Z553D-PAC and Zetag32-FS/A50) coagulants were found to be effective with remarkable performance to destabilise and neutralise the oil droplets to coalesce larger flocs to enhance the oil-water separation. Far and above, the cationic inorganic coagulants were more cost effective than the polymeric organic coagulants, even though, the inorganic coagulants were cheaper they had higher conductivity (salts), thus raising environmental concerns. In conclusion, the pre-treatment of the DAF process yielded more recovery of water and oil, and hence this step was economically viable. The RSM demonstrated to be more effective and reliable in finding the optimal conditions of the DAF process than the OFAT method. Thus, the RSM offered a better option than the OFAT, because it included both the interactional and individual factors.