Masters Degrees (Civil Engineering)

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The development of a latent heat thermal energy storage system using a phase change material for solar energy application.
(2010) Zulu, Njabulo Mziwandile.; Arnold, David R.
This investigation forms part of an attempt to provide an alternative to conventional power generation technologies that use fossil fuels which have impact on global warming. The field of this investigation covers the development of a latent heat thermal storage system which has a potential of conserving available solar energy. The advantages of using thermal energy storage that have been found previously include reduced energy cost, energy consumption, equipment size and pollutant emissions, also increased flexibility of operation, efficiency and effectiveness of equipment utilization. Traditionally, available heat has been stored in the form of sensible heat (typically by raising the temperature of the energy storage medium) for later use. Latent heat storage on the other hand, is a young and developing technology which has found considerable interest in recent times due to its advantages over sensible heat storage which include smaller temperature swing, smaller size and lower weight per unit of storage capacity. It has been demonstrated that, for the development of a latent heat thermal energy storage system, the choice of the phase change material (PCM) as well as the heat transfer mechanism in the PCM play important roles. In this study, a suitable phase change material and an appropriate heat transfer enhancement technique are identified for utilization in a proposed latent heat thermal energy storage system. Also included, is the design of the proposed heat storage system.
Investigation into the denitrification of high strength landfill leachate using pine bark and raw and composted commercial garden refuse as a carbon source : column studies.
(2010) Browne, A. J.; Trois, Cristina.
Landfill leachate, the liquid discharge from Municipal Solid Waste (MSW) landfills, is the combination of the surface runoff and ground water that percolates through the waste and the liquid contained in the waste itself and is considered to be toxic and presents a potential harm to the environment. Raw leachate contains high concentrations of biodegradable and non-biodegradable carbon as well as high concentrations of ammonia nitrogen. Traditionally, landfill leachate has been treated biologically through aerobic processes which reduce the biological carbon to carbon dioxide and biomass (bacterial growth) and ammonia nitrogen to nitrates. Unfortunately this is not sufficient to protect the environment from harm. It is necessary to further treat the leachate anaerobically to transform the nitrates to elemental nitrogen which is removed from the leachate as nitrogen gas. Biodegradable carbon is often the rate limiting substrate as carbon is consumed during the preceding nitrifying phase. Biodegradable carbon can be supplemented through the addition of methanol, at great expense Leachate from the Mariannhill Landfill site is currently treated aerobically in a sequencing batch reactor where nitrification is achieved. The nitrified leachate is then used as a dust suppressant on the current site. It is anticipated that in 2012 the Land fill site would have reached capacity thereby eliminating the need to irrigate and leaving the site with an excess of nitrified leachate that will present an environmental risk. The denitrifying performance of raw commercial garden refuse, pine bark and composted garden refuse as a growth medium and carbon source was investigated through the establishment of batch and column tests. CGR Raw proved the most successful of the three growth media, achieving full denitrification at a loading rate of 1700 mg NO3-N/kg of substrate/day.
An investigation into the mechanical biological pretreatment of garden waste using forced aeration and it impact on carbon emissions reduction potential
(2010-08-31) Iyilade, Yemisi
Disposal of garden waste is a major concern globally and particularly in a developing
Identification, quantification and classification of risks pertaining to building contractors in the JBBCC (Principal Building Agreement)
(2010-09-06) Harinarain, Nishani.
Risks are present in every aspect of business. As one of the biggest industries worldwide, the construction industry is plagued with risks. Being such a large industry, there are hundreds of contracts signed every day. These contracts range from new construction, refurbishment to maintenance. Some projects are simple and worth few thousands of dollars where others are complex and may cost hundreds of millions. Irrespective of how simple or complex the project is, all projects are exposed to risk and can go wrong (Edwards and Bowen, 2005). Construction is governed by complicated contracts and involves complex relationships in several tiers (Abdou, 1996). According to Sawczuk (1996) as soon as the employer and the contractor have signed a contract they have taken on board risks. Their awareness of the risk and the steps to be taken to manage their share of the risk, will determine the likelihood of problems occurring. Construction projects have an abundance of risk, contractors cope with it and owners pay for it. The construction industry is subject to more risk than any other industries. Taking a project from initial investment appraisal to completion and into use is a complex and time-consuming design and construction process. It requires a multitude of people with different skills and a great deal of effort to co-ordinate a wide ranges of disparate, yet interrelated, activities. Inevitably, this complex process is compounded by many unexpected events that may cause loss to the client and other involved parties (Shen, 1999; Flanagan and Norman, 1993). According to Carter et al. (1997) the construction industry is facing a more challenging environment than any time in the past. Client expectations have grown higher and they call for better quality and service. Smith (1998) highlighted that for years the South African building industry had a very poor reputation in managing construction risks. These risks could be prevented or reduced if management takes action at early stages ofthe project life cycle. In order to overcome these limitations and improve the image of the South African construction industry, this research aims to develop an innovative framework to enable construction contractors to identify, quantify and classify the risks associated with the Joint Building Contracts Committee (JBCC) Principal Building Agreement (PBA). This will help making decisions on informed bases. In addition, it will enable contractors develop particular course of actions to mitigate the effects ofthese risks. The research methodology designed to achieve this aim consisted of literature review, questionnaire and interview. Firstly, the literature review was used to review risk management in construction, construction contracts, Risks are present in every aspect of business. As one of the biggest industries worldwide, the construction industry is plagued with risks. Being such a large industry, there are hundreds of contracts signed every day. These contracts range from new construction, refurbishment to maintenance. Some projects are simple and worth few thousands of dollars where others are complex and may cost hundreds of millions. Irrespective of how simple or complex the project is, all projects are exposed to risk and can go wrong (Edwards and Bowen, 2005). Construction is governed by complicated contracts and involves complex relationships in several tiers (Abdou, 1996). According to Sawczuk (1996) as soon as the employer and the contractor have signed a contract they have taken on board risks. Their awareness of the risk and the steps to be taken to manage their share of the risk, will determine the likelihood of problems occurring. Construction projects have an abundance of risk, contractors cope with it and owners pay for it. The construction industry is subject to more risk than any other industries. Taking a project from initial investment appraisal to completion and into use is a complex and time-consuming design and construction process. It requires a multitude of people with different skills and a great deal of effort to co-ordinate a wide ranges of disparate, yet interrelated, activities. Inevitably, this complex process is compounded by many unexpected events that may cause loss to the client and other involved parties (Shen, 1999; Flanagan and Norman, 1993). According to Carter et al. (1997) the construction industry is facing a more challenging environment than any time in the past. Client expectations have grown higher and they call for better quality and service. Smith (1998) highlighted that for years the South African building industry had a very poor reputation in managing construction risks. These risks could be prevented or reduced if management takes action at early stages ofthe project life cycle. In order to overcome these limitations and improve the image of the South African construction industry, this research aims to develop an innovative framework to enable construction contractors to identify, quantify and classify the risks associated with the Joint Building Contracts Committee (JBCC) Principal Building Agreement (PBA). This will help making decisions on informed bases. In addition, it will enable contractors develop particular course of actions to mitigate the effects ofthese risks. The research methodology designed to achieve this aim consisted of literature review, questionnaire and interview. Firstly, the literature review was used to review risk management in construction, construction contracts,
The regional effect of water table lowering in the Durban area
(2010-09-09) Baxter, Brian Thomas.
No abstract available.
The design and development a mechanised support system for tabular stopes.
(2010-09-13) Naidoo, Dushendra.
Investigation of turbidity and chlorine disinfection in South African waters.
(2010-10-19) Moodley, Ubendra.
All natural waters containing particulate matter, such as clay, silt, colloidal particles, plankton
Evaluation of PCI reverse osmosis membrane on landfill leachate.
(2010-10-20) Rambridge, Vischal.
The specific objective of this study was to evaluate a PCI reverse osmosis membrane for
Flood estimation for roads, bridges and dams.
(2010-10-20) Parak, Mohamed.; Pegram, Geoffrey Guy Sinclair.
Flood estimation can be classified into two categories, i.e. flood prediction and flood forecasting. Flood prediction is used for the estimation of design floods, which are floods associated with a degree of risk of being equalled or exceeded. Predictions are needed for the design and construction of infrastructure that are at risk to flowing water. Flood forecasting is used for the estimation of flood flows from an impending and/or occurring rainfall event (i.e. the estimation of the magnitude of future flood flows with reference to a specific time in the future). These are needed by catchment and disaster managers for the mitigation of flood damage. The estimation of flood magnitudes for flood forecasting requires the specific knowledge of prevailing surface conditions which are associated with the processes of rainfall conversion into flood runoff. In order to best achieve this, a distributed model (in order to exploit remotely sensed data and capture the spatial scale of the phenomenon) is used to continuously update the surface conditions that are important in this conversion process. This dissertation focuses on both flood estimation categories. In the first part of the dissertation, attention is given to the improvement of two simple event-based design flood prediction methods currently in use by design practitioners, namely the regional maximum flood (RMF) and the rational formula (RF) by comparison with statistically modelled historical flood data. The second part of the dissertation lays the theoretical and practical foundation for the implementation of a fully distributed physically-based rainfall-runoff model for real-time flood forecasting in South Africa. The TOPKAPI model was chosen for this purpose. This aspect of the research involved assimilating the literature on the model, testing the model and gathering and preparing of the input data required by the model for its eventual application in the Liebenbergsvlei catchment. The practical application of the model is left for a follow-up study.
Long term emission from pre treated waste : column studies.
(2010-10-20) Marchetti, Raffaello.
Emissions resulting from waste degradation processes have a high polluting potential
The characterization of stormwater runoff from road surfaces.
(2006) Chrystal, Clinton Paul.; Stretch, Derek Dewey.
The water quality of stormwater runoff from various road surfaces in Durban, KwaZulu- Natal was characterised by monitoring programmes established at four study areas. The investigation focussed on obtaining representative stormwater samples in order to quantitatively identify pollutant constituents transported within stormwater runoff from road surfaces during rainfall events. Stormwater runoff is a leading cause of degradation in the water quality of receiving water bodies. A review of sampling methods and equipment, informed by the objectives and resources of this investigation, resulted in the development of a stormwater runoff sampler. An economical flow weighted composite sampler was designed, developed and tested. The sampler produces one representative composite event mean concentration sample. Controlled laboratory experiments, computer simulations and field tests were conducted in order to test and calibrate the sampler. The product of the event mean concentration and total runoff volume estimated provide an estimation of the total pollutant loading from a particular drainage area. Twenty stormwater runoff event mean concentration (EMC) and atmospheric deposition samples were collected over an eighteen month period. The characterisation of stormwater runoff for this investigation included heavy metals, oxygen demanding substances, sediments and physico-chemical analysis for pH, conductivity and water hardness. Chemical analysis indicates that the pollutant levels of constituents sometimes exceeded EMCs reported internationally. The majority of contaminant EMCs exceeded the South African wastewater discharge general and special limits. The results also indicate a 60% reduction in lead (Pb) levels since the introduction of lead-free fuel in South Africa in January 2006. The findings from this investigation will provide decision-makers with an improved local data base for estimating the impacts of road transportation systems on water quality. A comparison between the four study areas also provides guidance concerning the variability of stormwater quality from different road surfaces and usage patterns.
Stabilisation of waste in shallow test cells: focus on biogas.
(2006) Chetty, Nevendra Krishniah.; Trois, Cristina.
Present day society generates large volumes of waste that present an environmental hazard when disposed of in landfills. As our population grows, so does the volume of waste generated and hence the threat to our environment. One method of reducing harmful emissions in landfills is the mechanical-biological pretreatment of waste prior to landfilling. The purpose of this dissertation is to investigate the degree of stabilization of waste in shallow landfills (simulated by test cells) with particular focus on biogas production and quality. Municipal waste was composted in aerobic, open windrows for periods of eight and sixteen weeks. Five test cells, designed and operated according to the PAF model (Pretreatment, Aeration and Flushing) were constructed at the Bisasar Road landfill site. These cells were used to simulate large scale municipal landfill sites. They were filled with fresh and pretreated waste and were used to monitor the dynamics of prolonged aeration and degradation of waste over a period of six months. The cells were monitored on a weekly basis while being aerated. Two flushing events were conducted at the beginning of the passive aeration. Gas emissions were also monitored by recording the methane, carbon dioxide and oxygen volumes per volume of air in probes strategically placed in each cell. These results were then analysed to assess the effect of mechanical-biological pretreatment of municipal solid waste on the emission quality of sanitary landfills and the appropriateness of prolonging the aeration in shallow landfills, as often used in sub-tropical countries. It was found that the design of the test cells was appropriate for the landfilling and stabilization of waste that was aerobically treated. After six months in the test cells, analysis of the waste from each cell showed that the waste was completely degraded. The PAF model, when applied to shallow landfills, is very effective in stabilising waste and would be appropriate for a sub-tropical climate. Waste that is pretreated, placed in shallow landfills, initially flushed and then aerated over a six month period was fully stabilized. The requirement for such treatment would be relatively small amounts of waste, a wet climate and the availability of open space for shallow landfills. This method, therefore, would be very appropriate in a South African context. The major problem with this method may be the generation of large quantities of leachate which will have to be treated and disposed of in an environmentally safe manner.
An economic comparison of the waste management schemes employed in Cape Town and Johannesburg.
(2006) Stotko, Oliver.; Trois, Cristina.
The disposal of waste into landfill sites is currently the most commonly employed method of dealing with waste in South Africa as well as internationally. However the global trend towards operating waste management systems in a more sustainable way has lead to the need to reverse this situation towards a waste management system that predominantly makes use of waste minimization schemes to deal with waste and relies minimally on waste disposal. The focus of this research was to determine which waste minimization schemes would be most effective in the Municipal Solid Waste Management Systems (MSWMS) of Cape Town and Johannesburg with regard to achieving this reversal in an economically sustainable manner. The method used to achieve this objective was threefold, firstly requiring the development of a waste flow diagram for each respective city, followed by the development of a waste stream model based on the specific flow diagram and finally the extension of this material model into an economic model. The models were developed in Microsoft Excel and work on the premise that each particular stream (separate collected waste, transfer station waste, etc) of the MSWMS concerned has a particular associated cost (defined as cost per ton of waste processed). The model operates on the principle that under several pre-determined constraints the Excel Solver function calculates the optimal flow rates of the various waste streams which give the minimum overall MSWMS cost for future years. The developed model has shown that the recovery of waste reduces the overall MSWMS costs until a threshold value (at which point under the proposed system all economically recoverable waste has been exhausted). Different waste minimization schemes were found to be appropriate for each respective city. However, the use of Material Recovery Facilities (MRFs) to recover recyclables has been shown to be a viable waste recovery scheme for both Cape Town and Johannesburg. Cape Town is in the process of implementing the development of MRFs in conjunction with existing transfer stations, while it is envisaged that MRFs will be developed on all of Johannesburg's Municipal landfill sites in the future. Significant changes to the MSWMS of both cities are required for their respective landfilling waste streams to be substantially reduced in accordance with the Polokwane Declaration. Decreasing the landfilled waste stream is not only required by legislation, but the developed model has shown that the recovery of waste also reduces the overall MSWMS costs.
Optimization of the construction of VIP toilet sanitation at clinics in rural area.
(2009) Dilrajh, R.; Trois, Cristina.
No abstract available.
The study of the kinetics of degradation of mechanical-biological pretreated waste using test cells.
(2010-11-02) Simelane, Oscar Thamsanqa.
This research was carried out at the Bisasar Road Landfill site, Durban, South Africa,
Environmental impacts of the construction phase of an intensive development project on a coastal forest wetland : case study : Seaward Estates, Ballito.
(2011-01-14) Appelcryn, Anton.; Trois, Cristina.
Storm water runoff is a leading cause of degradation in the water quality of receiving water bodies. Although legislation requires that Environmental Impact Assessments (EIA) are performed and Environmental Management Plans (EMP) put in place for the construction of high density housing developments, there is generally very little evidence that real measures are developed to monitor and actually assess the extent of the impact that construction activities have on the environment during the physical construction stage. The water quality of stormwater runoff from a mixed use catchment including construction sites in Seaward Estates, Ballito, KwaZulu-Natal that enters a coastal forest wetland system was characterised by monitoring programmes established at three study areas. The effect thereof on the quality of the wetland water and sediments was further monitored at five points along the drainage line of the system. The investigation focussed on obtaining representative stormwater samples in order to quantitatively identify pollutant constituents transported within stormwater runoff from construction sites during rainfall events. Storm water runoff event mean concentration (EMC), atmospheric deposition and wetland water and sediment samples were collected over an eight month period. The characterisation of stormwater runoff for this investigation included heavy metals, oxygen demanding substances, sediments and physico-chemical analysis for pH, conductivity and ammonia and nitrates. The majority of contaminant EMC exceeded the South African wastewater discharge general and special limits. The findings from this investigation will provide planners and decision-makers with a greater understanding of the pollution dynamics of construction sites aiding in improved best management practice decisions with regard to minimizing impacts on coastal forest wetlands and water resources. This will lead to improved EMP and stormwater management plans (SWMP) incorporating stormwater pollution prevention plans (SWPPP) for construction sites.
Modelling of the water balance and nutrient dynamics of Mhlanga Estuary.
(2011-01-19) Lawrie, Robynne Angela.
Waste water discharge into a temporary open/closed estuary (TOCE) system introduces two main concerns namely (1) the effects on the water balance of the system (quantity) and (2) the effects on the nutrient dynamics (water quality). Changes to mouth breaching patterns can severely impact the hydrological and ecological functioning of TOCEs, while excessive nutrient loading can lead to eutrophic conditions and algal blooms. Algal blooms occur when residence times during closed mouth conditions exceed the time scale for growth of the microalgal community. The aim of this study was to formulate a model in order to predict eutrophication events using the Mhlanga Estuary as a case study. The Mhlanga Estuary is situated approximately 19 km northeast of Durban and has a small catchment «100km2 ). The Phoenix and Mhlanga waste water treatment works (WWTW) collectively discharge approximately 20MI of treated effluent into the Mhlanga River per day. A simple daily-time-step water balance model was selected to model the hydrodynamics of the system. The model included various inputs and outputs of the system, residence time, storage, breaching water levels and time for mouth closure to occur. The result of the water balance model was a daily prediction of the mouth state and volume, and an indication of the breaching frequency. Observed mouth state data and measured water levels were used to test the model. In order to predict eutrophication events and trends at the Mhlanga Estuary, it was required that the conditions at which this would occur be investigated. This included the collection of samples (physico-chemical and chlorophyll-a) on a weekly basis for three months, a period that included three breaching events. Due to the complexity required in developing a nutrient dynamics model, a simpler approach was selected. The grey water index (GWI) was formulated in order to account for nutrient loadings into the estuary. WWTW discharge data were provided by eThekwini Municipality Water and Sanitation (EMWS). Initial results showed that under ideal conditions, an algal bloom would occur approximately fourteen days following re-closure of the Mhlanga mouth. The eutrophication index (E j ) was then formulated to account for both residence time and nutrient concentrations. The Ej at which eutrophic conditions can be expected was found to be about 50 %. It is important to note that this value for Ej is expected to be site specific and only accounts for the Mhlanga Estuary, but the concept can be generalized to other similar estuaries. Water levels simulated using the water balance model and observed mouth state data produced similar levels to those measured by DWAF. Following simulations of different flow scenarios (75% and 150% increase in WWTW discharges), it was found that an increase in capping flows resulted in more frequent breaching events and longer open mouth conditions. The risk of eutrophic conditions also increased with an increase in WWTW capping flows. Algal blooms are predicted to continue despite more frequent breaching events induced by an increase in capping flows.
Spatio-temporal rainfall estimation and nowcasting for flash flood forecasting.
(2007) Sinclair, Scott.; Pegram, Geoffrey Guy Sinclair.
Floods cannot be prevented, but their devastating effects can be minimized if advance warning of the event is available. The South African Disaster Management Act (Act 57 of 2002) advocates a paradigm shift from the current "bucket and blanket brigade" response-based mind set to one where disaster prevention or mitigation are the preferred options. It is in the context of mitigating the effects of floods that the development and implementation of a reliable flood forecasting system has major significance. In the case of flash floods, a few hours lead time can afford disaster managers the opportunity to take steps which may significantly reduce loss of life and damage to property. The engineering challenges in developing and implementing such a system are numerous. In this thesis, the design and implement at ion of a flash flood forecasting system in South Africa is critically examined. The technical aspect s relating to spatio-temporal rainfall estimation and now casting are a key area in which new contributions are made. In particular, field and optical flow advection algorithms are adapted and refined to help predict future path s of storms; fast and pragmatic algorithms for combining rain gauge and remote sensing (rada r and satellite) estimates are re fined and validated; a two-dimensional adaptation of Empirical Mode Decomposition is devised to extract the temporally persistent structure embedded in rainfall fields. A second area of significant contribution relates to real-time fore cast updates, made in response to the most recent observed information. A number of techniques embedded in the rich Kalm an and adaptive filtering literature are adopted for this purpose. The work captures the current "state of play" in the South African context and hopes to provide a blueprint for future development of an essential tool for disaster management. There are a number of natural spin-offs from this work for related field s in water resources management.
Management and production techniques in the manufacturing and service industries and how it relates to the construction industry.
(2011-01-21) Pickering, Colin.; Pearl, Robert Gilfillan.
This dissertation is concerned with the future of the construction industry in South Africa and the ability to improve. Continuous growth is predicted through to the year 2015 and beyond, it is considered that to meet this challenge the South African construction industry must achieve substantial improvement and change. South Africa is a developing nation with ambitious objectives to improve social development and growth through delivery of infrastructure and other areas including, municipal development, hospitals, roads, water, electricity and government facilities. It is essential that South Africa has a construction industry that can develop capability and capacity to achieve sustainable growth. Current management thinking acknowledges that the best management and production principles are transferable. This is not a new concept or proposal, early management and production theorists and applicators such as Frederick Taylor, Frank B Gilbreth and Henry Ford all held the view that best practice techniques are transferable in application. By researching and presenting current successful management and production practices it intends to identify principles that can be adopted for change and improvement by the South African construction industry. A current general review of the South African construction industry has been undertaken to place it in context regarding the adoption of these best practice principles. The research will adopt a qualitative approach; it will be subjective and contain descriptions of techniques, people interactions, observations and assumptions. The principles addressed in this research are Benchmarking, Lean Production and Supply Chain Management; they have been selected as current best practice and as having significant use and proven continued success. They are presented in a format to allow understanding of the principles now developed and to illustrate via existing case studies, successes in application. Conclusions are made on individual aspects, on common core practices existing in all three principles and the current state of the South African construction industry. Recommendations are made and further areas of research suggested.
Environmental management strategy : Krantzkloof Nature Reserve, a case study.
(2006) Seaman, Paul.; Trois, Cristina.
KZN Nature Conservation Services budgetary cuts for the KrantzkloofNature Reserve (KNR) has led to economic shortfalls in important areas like facilities maintenance and invader plant control. The study has found that the benefits of maintaining KNR, determined from the estimated Total Economic Value (TEV), are huge and far outweigh the budget shortfall. The shortfall has been closed by user charging, the timing of which has prevented any deterioration in the facilities and ecology ofKNR due to budget cuts. Facilities maintenance needs to be prioritized to protect the user charge funding base and alien invader control needs to be prioritized due to escalating costs and the magnitude of the problem. The study has found that subcatchment stakeholder groups in the developing Emolweni forum, within which KNR is strategically placed, are strongly associated with local conservancies which will essentially provide the backbone for the envisaged forum. In order for stakeholder groups to be more representative, however, it is important for local conservancies to fmd a way to draw in community groups not normally involved in conservation work. The forum should provide networking and support for projects like environmental education, income generation and rehabilitation that will allow these community groups to participate in conservation work in a meaningful way. Delivery should occur through strategically placed community institutions like schools and clinics and should target young people and the unemployed. Nature reserves have largely untapped resources and a quasi- option value project is explored that combines alien vegetation control with the development of an indigenous nursery in an ecological and economic sustainable manner. It is envisaged that income derived from the sale of horticultural plants may substitute the income derived from medicinal plants and thus reduce the pressure applied on KNR's threatened resources by the unemployed. The study recommends that the subcatchment be divided into manageable units, based on a situational analysis, out of which particular criteria and objectives can be developed. Surveys, inventories, mapping and research activities should be carried out, with reports on the state or use of soil, water and biota submitted to the forum, which can then provide management solutions.

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