Communities around the globe are confronted by environmental challenges such as waste management. These challenges are further aggravated by factors such the increasing volumes of waste, landfills that are running out of capacity and scarcity of suitable land to construct new landfill sites. The National Waste Management Strategy requires participation from all members of society including households, businesses, community organisations, nongovernmental organisations, parastatals and the three spheres of government, to promote practices that minimise the volumes of waste generated. The purpose of the research was to assess and investigate the current waste management practices at the Cape Peninsula University of Technology (CPUT), and recommend a waste management system. The research employed a quantitative approach, where participants were asked to complete a survey questionnaire. A literature review was conducted on waste management at higher learning institutions, with particular focus on the contribution that a university can make in alleviating some of the adverse effects of waste management. The outcome of the review highlighted some of the opportunities and barriers that can either disrupt or augment the process of implementing a waste management system. The results from the research revealed that CPUT does not conform to the hierarchy of waste management, and there is no waste management policy in place. The effect of this is that the stakeholders were not satisfied with the lack of leadership on waste related challenges. By developing a policy, providing leadership, conducting awareness campaigns and prioritising environmental challenges such responsible management waste, could improve the image of the institution in the eyes if its stakeholders.

Due to urbanization, industrialization and population increase, a substantial increase occurred in the number of vehicles and hence large numbers of end-of-use tires are being disposed every year. The vast majority of these tires are stockpiled or used as a fuel for combustion which, in both cases, affects the environment detrimentally. The use of tire rubber in cement-stabilized aggregate mixtures (CSAMs) will ensure beneficial use of large quantities of these waste materials, saving natural resources and may enhance the properties of CSAMs especially these related to brittleness and sensitivity to fatigue failure. Research was undertaken to investigate, at macro and mesoscale levels, the effect of both rubber and degree of stabilization and their combination on the behaviour of CSAMs in terms of the most influential pavement design properties under different static and dynamic modes of loading. These properties are strength, stiffness and fatigue. A range of testing equipment, methodologies and tools was developed, suggested and implemented to perform this investigation. Further investigation was also conducted to provide better understanding of the damage and failure mechanism through quantitative studying of the fractured surface, internal structure and surface cracking patterns under different testing modes. The results of this study revealed that the addition of rubber has a negative effect on the compaction efficiency, compressive, flexural and tensile strengths while the stiffness, under different testing modes, was slightly reduced. In addition, a tougher mixture was produced after rubber-modification which means a change from a brittle to a more ductile behaviour. This behaviour was observed through different stiffness modulus evaluation methods. On the other hand, increase in cementation level has resulted in an increase in both strength and stiffness for both reference and rubberized mixtures. However, the decrease in the mixtures’ strength due to rubberization was more obvious in highly cemented mixtures than the lightly cemented ones. On the other hand, a greater decline in the mixtures’ stiffness, due to rubber incorporation, was observed at low cement contents. This behaviour is related to the void-like behaviour which depends, to large extent, on the relative stiffness between rubber and surrounding matrix. Quantification of the fractured surfaces and cracking pattern utilizing the photogrammatry and fractal dimension concepts, respectively, revealed that the addition of rubber resulted in rougher and more tortuous cracks and increases disperse-ability of these cracks. This means the rubber-modification changed the cracking pattern which implies better load transfer through the cracks and less risk of reflection cracking. The investigation of the internal structure, at mesoscale level, showed that the cracks were propagated through the rubber particles at all investigated cementation levels. This contributed to a lengthening of the crack path and to the delaying of crack propagation by absorbing and relieving the stresses at the crack tip, especially at the microcrack level. The latter mechanisms are behind toughness and fatigue improvement. Evaluation of rubber distribution revealed uniform distribution and this decrease as rubber content increases. The results also indicated an improvement in the fatigue life for all rubber replacement levels. This was valid at all cementation levels. In terms of modulus degradability, rubberization of the cemented mixture has only a slight effect on this property while larger permanent deformation was accumulated after rubber inclusion. It was observed that the poorly cemented mixtures showed greater stiffness modulus degradation. Pavement analysis and design study showed that the decrease in the mixtures’ strength overshadowed any improvement due to both mitigation of mixtures’ stiffnesses or fatigue life enhancement. However, this is not the case for poor rubber mixtures where this mixture showed better behaviour than the reference mixtures.

No description available.

published_or_final_version / Public Administration / Master / Master of Social Sciences

The discovery of DNA has been one of the biggest catalysts in genomic research. Sequencing has enabled us to access the wealth of information encoded in DNA and has provided the basis for ground-breaking achievements such as the first complete human genome sequence. Furthermore, it has tremendously advanced our understanding of life-threatening genetic disorders and bacterial and viral infections. With the recent advent of next generation sequencing (NGS) technologies, sequencing became accessible to the majority of researchers and made metagenomic sequencing widely available. However, to realise its true potential, sophisticated and tailor-made bioinformatic programs are essential to translate the collected data into meaningful information. My thesis explored the potential of resolving fine-scale variation in NGS data. The identification and correction of artificial fine-scale variation in the form of biases and errors is imperative in order to draw valid conclusions. Furthermore, resolving natural fine-scale variation in the form of single nucleotide polymorphisms (SNPs) and closely related species or strains is critical for the development of effective treatments and the characterisation of diseases. In recent years, Illumina has emerged as the global market leader in DNA sequencing. However, biases and errors associated with this high-throughput sequencing technology are still poorly understood which has precluded the development of effective noise removal algorithms. In addition, many programs were not designed for Illumina data or metagenomic sequencing. Therefore, a better understanding of the idiosyncrasies encountered in Illumina data is essential and programs must be tested and benchmarked on realistic and reliable in silico data sets to reveal not only their true capacities but also their limitations. I conducted the largest in vivo study of Illumina error profiles in combination with state-of-the-art library preparation methods to date. For the first time, a direct connection between experimental design factors and systematic errors was established, providing detailed insight into the nature of Illumina errors. Further, I tested various error removal techniques and developed a sophisticated Illumina amplicon noise removal algorithm, enabling researchers to choose optimal processing strategies for their particular data sets. In addition, I devised several simulation tools that accurately reflect artificial and natural fine-scale variation. This includes a flexible and efficient read simulation program which is the only program that can directly reflect the impact of experimental design factors. Furthermore, I developed a program simulating the evolution of a virus into a quasi-species. These programs formed the basis for two comprehensive benchmarking studies that revealed the capacities and limitations of viral haplotype reconstruction programs and taxonomic classification programs, respectively. My work furthers our knowledge of Illumina sequencing errors and will facilitate more accurate and effective analyses of sequencing data sets.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This research project focuses on sanitary sewer systems. When performing an analysis of a sewer drainage system with known constraints, an appropriate model needs to be chosen depending on the objectives of the analysis. Uncertainties are also present in the analysis of sewer drainage systems. The uncertainties and the errors in hydraulic models need to be understood and considered. The required level of accuracy and the type of hydraulic problem that needs to be solved may alter the complexity of the hydraulic model used to solve a drainage system. The wide variety of available simulation models further complicates model selection. With various models available, selecting the most appropriate model for a particular drainage system simulation is important. The various models for sewer drainage system analysis can be categorised in different ways. For example, it is possible to categorise models according to their purpose, which could be evaluation, design or planning. Evaluation models are mainly used to test whether existing systems or planned systems are adequate and require the highest hydraulic detail. Design models are used to determine the size of conduits within a drainage system and require moderate levels of hydraulic detail. Planning models are primarily used for strategic planning and decision making for urban or regional drainage systems and require the least amount of hydraulic detail. An understanding of the available models is required in order to choose the most suitable simulation model for the desired purpose. Some models are derived from the Saint-Venant equations of flow. The most detailed models are typically referred to as fully dynamic wave models and utilise all the components of the Saint-Venant flow equations. By removing terms from the Saint-Venant equations a kinematic wave model can be created. Some less complex models ignore basic principles of hydraulics in order to make assumptions that simplify the process of simulating flows. In this thesis three different models were compared: a detailed model using fully dynamic flow equations, a simplified model using kinematic wave equations and a basic model using contributor hydrograph routing equations. For the drainage system analysis SWMM-EXTRAN was used as the fully dynamic wave model, SWMM-TRANSPORT was used as the kinematic wave model and SEWSAN was used as the contributor hydrograph model. Two drainage systems situated in South Africa were used as case studies and are referred to as Drainage System A and Drainage System B in this thesis. The actual flow rate was recorded at two points with flow loggers, one in each of the two systems. The flow rate was continually recorded at 1 hour intervals for the period 1 July 2010 to 9 July 2010 in Drainage System A as well as in Drainage System B. The same input parameters were used for each model allowing the modelled flow rates to be compared to the measured flow rates. The models provided peak flow results that were within 2% of the measured peak flow rates and the modelled mean flows were within 8.5% of the measured mean flows in most situations. However, when rapidly varied flows occurred the kinematic wave and contributor hydrograph models returned conservative results as they were unable to account for hydraulic effects such as acceleration. The effect of acceleration became most pronounced up and downstream of drop structures and sections where the slope changed considerably. The kinematic wave and contributor hydrograph models were therefore unable to accurately simulate surcharge conditions. The results suggest that the fully dynamic wave model can be used in all scenarios. The kinematic wave model can be used for a design analysis if no hydraulic structures occur in the system. The contributor hydrograph model should not be used for an evaluation analysis, but can be used for a design analysis if a relatively high level of confidence in the parameter set exists and no areas of rapidly varying flow or hydraulic structures exist within the system. / AFRIKAANSE OPSOMMING: Hierdie navorsing projek is gefokus op riool dreineringsisteme. Wanneer ʼn analise van ʼn riool dreineringsisteem met bekende beperkinge onderneem word, moet ʼn geskikte model gekies word afhangende van die doelwitte van die analise. Onbekendes is ook teenwoordig in die analise van riool dreineringsisteme. Dit word belangrik dat die onsekerhede en die foute in hidroliese modelle moet verstaan en oorweeg word. Die verwagte vlak van akkuraatheid en die tipe hidroliese probleem wat opgelos moet word mag die ingewikkeldheid van die hidroliese probleem, wat gebruik word om ʼn rioolsisteem op te los, verander. Die wye verskeidenheid van beskikbare simulasie modelle bemoeilik verder die keuse van ʼn model. Met etlike modelle beskikbaar vir seleksie, is die mees geskikte model vir ʼn spesifieke dreineringsisteem simulasie belangrik. Die verskeie modelle vir riool dreineringsisteem analise kan op verskillende wyses gekategoriseer word. Byvoorbeeld, dit is moontlik om modelle te kategoriseer volgens hulle doel, wat evaluasie, ontwerp en beplanning kan wees. Evaluasiemodelle word hoofsaaklik gebruik om te toets of huidige of beplande sisteme voldoende is en of hulle die hoogs moontlike hidroliese besonderhede benodig. Ontwerpmodelle word gebruik om die grootte van ʼn leipyp binne ʼn rioolsisteem te bepaal en benodig matige vlakke van hidroliese besonderhede. Beplanningsmodelle word hoofsaaklik gebruik vir strategiese beplanning en besluitneming vir stedelike en landelike rioolsisteme en benodig die laagste vlak van hidroliese data. ʼn Begrip van die beskikbare modelle is nodig om ʼn keuse te maak rakende die mees geskikte simulasie model vir die verlangde doelwit. Sommige modelle is afkomstig van die Saint-Venant vergelykings van vloei. Die mees gedetailleerde modelle word tipies na verwys as die volledige dinamiese golf modelle en benut alle komponente van die Saint-Venant vloei vergelykings. Deur die verwydering van terme van die Saint-Venant vergelykings kan ʼn kinematiese golf model daargestel word. Sommige minder gekompliseerde modelle ignoreer die basiese beginsels van hidrologie om aannames te maak wat die proses van golf simulering vereenvoudig. In hierdie tesis is drie verskillende modelle vergelyk; ʼn gedetailleerde model wat volledige dinamiese vloeivergelykings gebruik; ʼn vereenvoudigde model wat kinematiese golfvergelykings gebruik en ʼn basiese model wat bydraende hidroliese versending vergelykings. Vir die dreineringsisteem analise was SWMM-EXTRAN gebruik as die volledige dinamiese golfmodel, SWMM-TRANSPORT was gebruik as die kinetiese golfmodel en SEWSAN was gebruik as die bydraende hidroliese model. Twee dreineringsisteme in Suid-Afrika was gebruik as gevallestudies en word na verwys as Dreineringsisteem A en Dreineringsisteem B. Die werklike vloeikoers was aangeteken by twee punte met vloeimeters, een in elk van die sisteme. Die vloeikoers was deurlopend opgeteken met 1 uur tussenposes vir die periode 1 Julie 2010 tot 9 Julie 2010 in Dreinering Sisteem A sowel as Dreinering Sisteem B. Dieselfde inset parameters was gebruik vir elke model wat dit moontlik gemaak het dat die gemoduleerde vloeikoerse met die gemete vloeikoerse vergelyk kon word. Die modelle het spits vloeiresultate voorsien wat binne 2% van die gemete spits vloeikoerse was en, in die meeste situasies, dat die gemoduleerde gemiddelde vloei binne 8.5% van die gemete gemiddelde vloei was. Wanneer vinnig varierende vloei voorgekom het, die kinetiese golf and bydraende hidrograaf modelle konserwatiewe resultate gelewer het, aangesien hulle nie in staat was om hidroliese effekte soos versnelling te verklaar nie. Die effek van versnelling was op sy duidelikste stroomopwaarts en stroomafwaarts onder valstrukture en by gedeeltes waar die helling aansienlik verander het. Die kinetiese golf en bydraer hidrograaf modelle was gevolglik nie in staat om oorladingsomstandighede akkuraat te simuleer nie. Die resultate wys dat die volledige dinamiese vloeimiddel gebruik kan word in alle omstandighede. Die kinematiese vloeimiddel kan gebruik word vir ʼn ontwerp analise indien geen hidroliese struktuur in die sisteem voorkom nie. Die bydraer hidrograaf model behoort nie gebruik te word vir ʼn evaluerings analise nie, maar kan gebruik word vir ʼn ontwerp analise indien ʼn relatiewe hoë vlak van vertroue in die parameter stel bestaan en geen area van vinnig veranderende vloei of hidroliese strukture binne die sisteem bestaan nie.

Hydrocarbon selective catalytic reduction (HC-SCR) is emerging as one of the most practical methods for the removal of nitrogen oxides (NOx) from light-duty-diesel engine exhaust gas. In order to further promote the chemical reactions of NOx-SCR by hydrocarbons, an understanding of the HC-SCR process at the molecular level is necessary. In the present work, a novel surface-reaction mechanism for HC-SCR is set up with emphasis on microkinetic analysis aiming to investigate the chemical behaviour during the process at a molecular level via detailed elementary reaction steps. Propane (C3H8) is chosen as the reductant of HC-SCR. The simulation is designed for a single channel of a monolith, typical for automotive catalytic converters, coated with a silver alumina catalyst (Ag/Al2O3). The complicated physical and chemical details occurring in the catalytic converter are investigated by using the numerical method of computational fluid dynamics (CFD) coupled with the mechanism. The C3H8-SCR reaction mechanism consists of 94 elementary reactions, 24 gas-phase species and 24 adsorbed surface species. The mechanism is optimised by tuning some important reaction parameters against some measurable data from experiments. The optimised mechanism then is validated with another set of experimental data. The numerical simulation shows good agreements between the modelling and the experimental data. Finally, the numerical modelling also provides information that is difficult to measure for example, gas-phase concentration distribution, temperature profiles, wall temperatures and the occupation of adsorbed species on catalyst surface. Consequently, computational modelling can be used as an effective tool to design and/or optimise the catalytic exhaust aftertreatment system.

Fuels: Non-renewable fossil fuels are the largest man-made contributor to global warming. Biofuel market share will increase, promoted by renewability, inherent lower net CO\(_2\) emissions, and legislation. The environmental and human health impact of diesel exhaust emission particulate matter (PM) is a major concern. Fossil diesel PM aftertreatment systems exist. Near future fuel PM research and the evaluation of current aftertreatment technology, highlight a route for future development. Using a holistic approach this body of work studies the interdependence between the fuel, the CI engine and associated aftertreatment system. The overall objective of this thesis is the evaluation of current diesel aftertreatment using renewable near future fuels. Diesel blends with 1st and 2nd generation biodiesel fuels are viable. Carefully selected blends like B20G10 can make all round regulated emission improvements. Green additive dimethyl carbonate (DMC) enhances diesel combustion by oxygenation. Regulated emissions of THC, CO (>30% reduced) and PM (50% reduced) for 2% DMC in diesel. 1st generation biodiesel (RME) is widely available. Combustion produces significantly less solid PM than diesel (<50%) and slightly more liquid PM. RME produces less particulate at nearly all particle sizes, but more of the small nano sized liquid SOF. The potentially negative health effect of nano-sized SOF material raises questions. There is a case for more research into the health effects of nano-sized SOF material. Oxygenated fuel combustion PM contains more voids (facilitates DPF oxidation), plus unregulated carcinogenic compounds are reduced. ii Aftertreatment: The efficiency of the oxidation catalyst for the near future fuels was comparable to diesel and PM matter at all particulate sizes is reduced for all near future fuels tested. Aftertreatment total PM filtration levels are >90% by mass >98% by number, for all fuels. For synthetically produced 2nd generation gas to liquid (GTL) fuels there are potentially DPF regeneration implications. Current aftertreatment solutions are as effective for bio alternatives as they are for fossil diesel. Biodiesels, green additives and aftertreatment are effective clean emissions improvements, until the promise of true zero emission vehicles is realised.

The world is facing the challenge of global warming and environment protection. On the other hand, the demand of electricity is growing fast due to economic growth and increase in population. Since the growth in demand is also a heavy factor in energy equations, then the renewable energy alone is not able to generate enough electricity to fill the gap within a short time of period. Therefore, fossil fuel such as coal fired power plants cannot be ruled out immediately due to their generation capacity and flexibility in load following. However, any new coal fired stations should be cleaner compared with traditional power plants. Supercritical power plants are one of the most suitable choices for environmental enhancement and higher efficiency. However, there has been an issue of whether or not to adopt this technology in the UK because it is not clear whether the performance for SC plants can satisfy the British Gird Code requirement. This thesis reports a study of dynamic responses of SC power plants through mathematical modeling, and simulation for Gird Code compliance. It also presents a new control strategy based on an alternative configuration of generalized predictive control for power plant control.

Hollow low density microspheres were prepared by adsorbing kaolin nanoparticles onto a polystyrene (PS) template. A cationic polyelectrolyte, poly(diallydimethylammonium chloride), was initially adsorbed on the PS to render the surface cationic enabling the kaolin nanoparticles to form a shell structure due to electrostatic attraction forces. An increase in ionic strength by the addition of 0.1 M NaCl increased the amount of polyelectrolyte adsorbed at the PS surface. Solvent relaxation NMR experiments indicated that solvent molecules were bound at the PS surface suggesting attached polymer chains. Zeta potential experiments indicated a change in the surface potential at the PS interface due to the addition of a polyelectrolyte, as little as 0.1 g m-2 of polyelectrolyte was required to change the PS surface potential. Surface saturation of the PS resulted in a zeta potential of 63.5 \(\pm\)2.6 mV, at pH 6.6 \(\pm\)0.2. Kaolin adsorption was determined by reduced sediment volume experiments and observed by the use of scanning electron microscopy (SEM). The influence of an increase in the kaolin ratio and the calcination process on the microsphere structure was investigated. When calcined at 1000 ºC for 60 min the microsphere properties exhibited a particle size (d50) of 11.2 \(\pm\)0.4 \(\mu\)m and a bulk density of 0.13 \(\pm\)0.01 g/cm3. The internal structure of the calcined microspheres were characterised by the use of SEM and focused ion beam (FIB) instruments. The characteristic properties of the calcined kaolin microspheres were determined by thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS).