The possibility of utilisation of microbially induced calcium carbonate precipitation as a potential remedial technology for sequestering divalent metallic contaminants in subsurface environment was explored. Contamination by heavy metals and radionuclides is a significant environmental problem. Incorporating metals in calcium carbonate minerals is a mechanism that may offer long-term removal of metallic cations. Stimulating native ureolytic bacteria by supplying required nutrient and chemicals to create alkaline conditions suitable for calcium carbonate precipitation may accelerate biomineralisation processes in polluted soil. This study reports the ability of a bacterium in soils, Sporosarcina pasteurii, to remediate range of heavy metal and radionuclide (by using non-radioactive proxies) concentrations in aqueous solutions and particulate media by inducing urea hydrolysis and calcium carbonate precipitation. However, bacterial activity is limited by heavy metals toxicity and availability, hence, initially the minimal inhibitory concentration (MIC) of metals to bacterial activity was estimated, without the presence of a metal precipitation mechanism (only metals ions and nutrient broth). Metals inhibited bacteria in the following order Cd >Zn >Cu >Pb >Sr. The bacterial cells showed an improved growth and metal toxicity resistance in presence of urea containing medium over their presence in urea-free medium. Cd, Pb and Sr were fully removed, whilst Zn and Cu were partially removed by this technique. Removal of heavy metals was strongly correlated with full removal of calcium and high pH increase then white precipitate was produced, suggesting that urea hydrolysis by bacterial cells did play a role. Finally, it was explored the effects of ground conditions (transport and availability of heavy metals, preferential flow and heterogeneous hydraulic conductivity) on biomineralisation process in porous media in different sand fractions (fine, medium and coarse). High removal rates were achieved in porous media especially for cadmium and strontium. It is resulted that the heterogeneity of hydraulic conductivity plays a main role in distributing bacterial activity and subsequent precipitation processes in porous media. XRF, XRD, SEM and EDX spectrum tests for sand samples showed the presence of calcite and aragonite in precipitation crystals. The gained results demonstrate that microbially induce calcium carbonate technique is a means of sequestration of soluble heavy metals via co-precipitation with calcium carbonate precipitation that can be useful for divalent heavy metal and radionuclides bioremediation.

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.

The promulgation of the minimum emission standards for the list of activities resulting in significant air pollution under the National Environmental Management: Air Quality Act, 2004 (Act No.39 of 2004) introduces a command – and – control regulation, in which the listed activities are required to obtain atmospheric emission licenses prior to operation. Under this regime, the listed activities are required to demonstrate compliance with the concentration-based minimum emission standards incorporated into their license, by conducting emission monitoring. Effective emission monitoring is dependent on the systematic implementation of a number of processes, procedures and protocols for emissions sampling, analysis and reporting. This study focused on development of a system for emissions monitoring, by establishment of the best practice on sampling procedures; criteria for emission measurement methods selection; quality assurance and quality control procedures; as well as data handling, reporting and compliance assessment procedures. The study recommends a model of emissions compliance monitoring system for South Africa, comprising of processes and procedures required for the acquisition of good quality, credible data to support effective implementation of the National Environmental Management: Air Quality Act, 2004. / Dissertation (MSc)--University of Pretoria, 2015. / Chemical Engineering / Unrestricted

In a world recently declared urban, each day technology plays a more important role in society. A majority of people seem to believe in technology not only for solving everyday problems and for supporting the current production and economic systems, but also for the redress of environmental problems that are caused to a large extent by the same technology that has driven society to the current standards. In this direction, megacities (i.e. cities with more than ten million inhabitants) represent a valuable example of both the problems caused by high urbanization rates and the possibility of solving them using technology. However, the mere development of technology does not guarantee its immediate adoption and successful implementation by a given society. In this thesis, one of the largest megacities in the world (i.e. in terms of population) was chosen as a case study for the analysis of the adoption and diffusion of environmental technology. Mexico City is studied through a set of interviews with local stakeholders from academia, government, industry and other external organizations such as non-profit organizations and international institutions. This approach resulted in the identification of different obstacles to the adoption and implementation of technologies, but also led to a successful case of technology adoption that allowed for the understanding of important traits that facilitated not only such adoption, but also the subsequent diffusion and spread to other cities. Although the thesis has a strong focus on the demand side (in this case Mexico City), the supply side (in this case the Swedish environmental technology sector) is also considered and analyzed. By using statistical data of common enterprise and economic nature, the composition of the sector was described and analyzed with the intention to identify important areas and behavioral traits that could give insight into the hindrances that the sector faces when exporting its offerings. Given the interest that the Swedish government has put in the sector for contributing to the country’s economic growth, the different studies commissioned for the assessment of the sector are also discussed in this thesis. The different conclusions and suggestions made by the different agencies entrusted with this task are shown and analyzed. Conclusions are drawn regarding the need for designing strategies that consider local conditions, that are flexible and adaptive to a highly dynamic environment and that pay particular attention to the development of strong demonstration projects that facilitate overcoming the distrust normally created when new technologies are introduced in a society. / Megatech

Miljö och miljöfrågor ar något som blir allt mer viktigt i takt med att nya miljöutmaningar växer fram. Som enskild medborgare kan man vara en del i att verka för en bättre miljö genom att återvinnahushållsavfall av olika slag och textilier, i någon av de återvinningscontainrar som finns placerade på platser över hela landet. Idag finns det inget sätt att kunna veta om den station dit man går för att kasta sitt avfall är full eller om det finns utrymme kvar. Organisationer som har containrar får i den mån det är möjligt förlita sig på statistik, men ofta händer det att en station har containrar som är överfulla. Det här projektet undersöker möjligheterna till ett system med mat enheter i återvinningscontainrar som själva laddar upp data till en server när fyllnadsnivån i containern ökat väsentligt. En prototyp för enmatenheten tas fram med hjälp av Arduinobaserad teknik och testas i containrar tillhörande organisationen Myrorna som bland annat bedriver insamling av kläder. Parallellt utvecklas enserverapplikation med en databas dit matenheten laddar upp sin matdata. En enkel iOS-app utvecklas som hämtar senaste rapporteringen från matenheten via servern och presenterar den. Matenhetens strömförbrukning undersöks och det visar sig att prototypens strömförbrukning gör att batterierna i teorin skulle racka mer än ett år. Kostnaden för prototypen ger en fingervisning om produktens framtida kostnad, vilken författaren anser vara låg. Med detta system i drift finns möjligheter att skapa applikationer till organisationer med containrar för att förbattra deras hantering av insamling av avfall. Informationen kan även ges, till exempel via en mobilapp, till den som är intresserad av att lämna avfall till återvinning. / The environment and environmental issues grows more and more important as new challenges in the topic appear. Citizens can help to improve the environment by recycling their household waste of various kind and textiles in some of the recycling stations that are located on places all over the country.Today there is no way to know if the station one wants to visit to recycle waste, has room left in thespecific container. Organisations that have and manage containrar today have to rely on statistics, but often it happens that a station have containrar that are completely full. This project investigates the possibilities of putting measuring devices into containrar that will upload data about the current fill level to a server, when the fill level changes significantly. A prototype for the measurement device is constructed using Arduino based technology and it is tested in containrar belonging to the organisation Myrorna that amongst other things collect used clothes. In parallell, a server application with a database is developed to which the measurement device uploads it’s data. Also developed is a simple iOS-app that retreives the latest information from the measurement device throughthe server and presents it. The power consumption of the measurement device is examined and it turns out that the batteries of the prototype in theory will last more than a year.The cost of the prototype gives a hint of the future product’s cost, which the writer considers to be low. With this system in use there are possibilities to create applications for organisations managing containrar to improve their handling of collecting waste. The information can also be delivered, for instance through a mobile app, to anyone who wants to leave their waste for recycling.

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.

<p>The focus of this thesis is on groundwater vulnerability assessment by process-based simulation models and data acquisition for these assessments. A modelling system for intrinsic groundwater vulnerability assessment in water supply areas was developed, consisting of flow- and transport models for the unsaturated zone and the groundwater zone, coupled to a geographical informa-tion system. The system was applied to a water supply area located close to a major road south of Stockholm. Chloride was used as an indicator in determining the vulnerability for groundwater contamination from the road. The approach was useful to illustrate the dynamic change of chlo-ride concentrations both during the stage of continuous application and after the applications was terminated. A structure and content of a database for flow and transport modelling, based on hydrogeological environments, was outlined. An existing hydrogeological parameter database, HPAR at the Geological Survey of Sweden (SGU), was examined as a potential source of data for the new database. Values for some important parameters needed for groundwater modelling, such as hydraulic conductivity and effective porosity, were lacking in the three municipal HPAR databases that were studied. It was suggested that these data should be added, together with information on the hydrogeological environments, for all geographical positions of interest. Without such minimum information, the efficient use of modelling tools could not be expected.</p><p>Typical profiles of three common Swedish hydrogeological environments (sand deposits, glacial till and clay covered areas) were used to represent generic input data to model simulations in the unsaturated zone so that the importance of soil, vegetation type and groundwater levels on turn-over times of conservative contaminants transported by natural recharge could be examined. The same profiles were used to predict the penetration depth of accidental liquid spills that occur at the land surface level. In the case of contaminant transport by natural recharge, water storage in the soil profile and vegetation type played an important role for turnover times. For liquid spills, the hydraulic con-ductivity was found to be of major importance, while the water retention properties were of less importance. Modelling, together with available data sources, were successfully used to demon-strate the vulnerability of different environmental conditions.</p>

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.