Dissertations / Theses on the topic 'Incineration – Waste disposal'

An extensive series of experimental tests were carried out at the Sheffield municipal solid waste incinerator plant (30 MW) from September 1988 to July 1989 to investigate the influence of the design and operating parameters on the performance of the incinerator which burns domestic and commercial wastes (500 ton/day). The following measurements were made around the plant: temperature measurements, pressure measurements, flue gas composition analysis and determination of physical and chemical properties of Sheffield refuse. Several other miscellaneous measurements were also made to monitor the effect of variation of operating parameters on the performance characteristics of the incinerator. A combustion model of Essenhigh type was then employed to model the combustion processes inside the solid refuse bed on top of the travelling grate. In addition a mathematical model of the finite difference type (FLUENT) was used to predict the three dimensional reacting flows (gaseous phase) within the incinerator geometry. Experimental measurements of gas composition, temperature and exit velocity were compared with model predictions. Modelling results were generally in good agreement with measurements. As a result of the test data and the mathematical modelling of the whole process, suggestions for design improvements for the Sheffield municipal solid waste incinerator were made which will substantially increase the efficiency, reduce emissions of pollutants and reduce the maintenance costs at the plant. These are: a) replacing the existing secondary air system with secondary air nozzles and the use of more secondary air (up to 20 % of total air) in order to generate turbulence in the high intensity combustion zone where it is most needed and b) introducing a baffle into the main stream inside the radiation shaft in order to lower the gas temperatures entering the precipitator and to remove the existing recirculation zone in the shaft.

The important role of black liquor in the pulp and paper industry has, been addressed and a review of conventional and potential alternative technologies has been made. Black liquor combustion properties and its combustion within a conventional recovery boiler, the principle of vortex combustion, and methods of computational fluid dynamics were summarized. In order to use the commercially available computational fluid dynamics package, PHOENICS, to simulate black liquor combustion in a vortex combustor, the black liquor combustion process was simplified and modelled and additional software programs were developed and attached to the commercial package. The developed module is capable of tracking trajectory paths of black liquor particles during combustion. A 250 kW vortex combustor was used for some experimental work. The combustor was first tested with natural gas and kerosene. The - combustion conditions were satisfied and their characteristics were presented. Atomization was the main technical problem in the combustion of black liquor. However, the environmental problem was also severe. The results were presented and discussed. Improvements of the system and further studied were suggested. Selection of a suitable turbulence model was made by comparing experimental data with the simulations from various turbulence models. Prandtl mixing length model gave closer predictions than k-? and k-1 model and therefore, it was used for the entire simulations. Simulations of natural gas combustion in a vortex combustor were made to establish skill and confidence in using the package, PHOENICS, to deal with combustion process. A series of black liquor combustion models were performed afterward using the particle tracking module developed. This led to the suggestion of a potential suitable geometry of a vortex combustor for black liquor incineration. The results were presented and discussed. Further simulation studies are also suggested.

In this study, the formation mechanisms, distribution characteristics, and potential environmental risks of hazardous air pollutants from industrial-scale waste incineration processes were investigated. First, to clarify the dominant formation mechanism of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) in a hazardous waste (HW) incinerator, three tests were designed by adding different precursors in phenol-containing raw materials. With the addition of p-dichlorobenzene, PCDD/F levels at the quenching tower outlet were ten times higher than levels observed at the inlet. This indicates that the quenching tower failed to suppress the formation of PCDD/Fs and surface-mediated precursor reaction is the dominant formation mechanism in low-temperature stages. Besides, adsoprtive memory effect in air pollution control devices (APCDs) also led to high PCDD/F emissions. These findings suggest that to control PCDD/F emissions, strict regulation of chlorine contents in feed materials and frequent cleaning of APCDs are necessary. Meanwhile, single particles and solid residues were collected from the same HW incinerator. Morphologies and elemental compositions of particles in flue gas and indoor air were characterized by transmission electron microscopy-energy dispersive X-ray spectrometry (TEM-EDS). Eight types of single particles were classified, as organic, soot, K-rich, S-rich, Na-rich, Fe-rich, mineral and fly ash particles. The heavy metal partitioning behavior study suggested that Hg, Cd and Pb were mainly enriched in fly ash through evaporation, condensation, and adsorption; while Cr, Cu, Mn, and Ni were mostly remained in the bottom ash due to their low volatilities. In addition, the study also investigated environmental behaviors of certain characteristic pollutants. Thrity-two soil samples surrounding a cement plant co- processing HW were collected and analyzed for the presence of 16 polycyclic aromatic hydrocarbons (PAHs) and 12 heavy metals. Ten samples were selected for PCDD/Fs analysis. The highest concentration of PCDD/Fs occurred 1200 meters downwind from the cement plant. Levels of ∑16 PAHs ranged from 130.6 to 1134.3 μg/kg in soil. Source identification analysis suggested that the cement plant was the most likely source of PAH contamination. The concentrations of Cd and Hg were on average two times and six times higher than background values, respectively. Both incremental lifetime cancer risk model (ILCR) for PAHs and potential ecological risk index (RI) for heavy metals indicate potential risks to the population and the environment surrounding the cement plant. Last, to identify whether waste incineration is a major source for airborne environmentally persistent free radicals (EPFRs), tree leaf samples were collected from 120 sites surrounding four waste incinerators and one urban area. EPFR concentrations on leaves ranged from 7.5 × 10 16 to 4.5 × 10 19 spins/g. For the 10 N.D. samples, they were all collected from areas inaccessible by vehicles. Although previous work has linked atmospheric EPFRs to waste incineration, the evidence in this study suggests that vehicle emissions, especially from heavy-duty vehicles, are the main sources. According to our estimation, over 90% of the EPFRs deposited on tree leaves might be attributed to automotive exhaust emissions, as a synergistic effect of primary exhausts and degradation of aromatic compounds in road dust

Municipal solid waste incineration (MSWI) is the most widely used solution in those countries where landfilling areas are limited. Incineration allows reducing the total volume of waste (up to 90%) and generating energy resulting from combustion. The main by-product generated in waste-to-energy plants is known as incineration bottom ash (IBA), which is a heterogeneous mixture of ferrous and non-ferrous metals, ceramics, and glass. IBA is classified as a non- hazardous material due to its composition rich in calcium oxide, silica, and iron. IBA composition and morphology are very similar to natural siliceous aggregates after an ageing treatment where the weathered bottom ash (WBA) is obtained. This maturation process makes feasible the WBA valorisation as a secondary aggregate in the field of construction and civil engineering. Moreover, the high percentage of glass and aluminium found in the WBA would allow its valorisation as a precursor in the alkali-activated binders (AABs) formulation. The main goal of this PhD thesis was the scientific and technological development of new AABs based on the alkali activation of WBA (AA-WBA binders), to reduce the use of ordinary Portland cement (OPC) in building and civil engineering fields. In this sense, this aim is related to the use of more sustainable cement-based materials, which promote the circular economy and zero-waste principle through the valorisation of WBA. The potential of WBA as a precursor in the AA-WBA binders’ formulation was evaluated along with the PhD thesis through different studies that can be classified into four blocks. The first block was based on the evaluation of the WBA potential as a precursor in AABs based on its particle size. This study demonstrated the variability in the reactive SiO2 and Al2O3 availability as a function of the particle size. The potential of the entire fraction (EF) and the 8-30-mm fraction highlighted the possible use of them as precursors in the AABs formulation. The second block of this thesis was focused on the study of AA-WBA binders using the WBA as a sole precursor. Mixtures of sodium silicate (WG) and NaOH (2M, 4M, 6M, and 8M) were used as alkaline activator solutions to assess the effect of the NaOH concentration on the final properties. It was demonstrated the possibility of developing AA-WBA. The influence of alkaline activator solution concentration on the final properties of the AA-WBA was evidenced, obtaining better mechanical performance with the use of the WG/NaOH 6M solution. The results revealed the enhancement in the mechanical properties when the 8-30-mm fraction was used. However, the environmental results revealed arsenic and antimony leaching values that require further research to validate the environmental feasibility of AA-WBA. In the third block, the 8-30-mm fraction was mixed with other precursors with greater availability of Al2O3 (metakaolin and PAVAL®). The main purpose was to improve the mechanical properties and the heavy metal stabilisation effect of the AA- WBA obtained in the second block. In both cases, mechanical performance was improved due to the inclusion of Al2O3. However, the environmental properties continued to show leaching values that did not ensure the environmental viability of the AA-WBA binders. Finally, the fourth block of the thesis was focused on carrying out an environmental and ecotoxicological assessment to validate the use of AA-WBA binders as construction material. The results showed a medium-low level of ecotoxicity in the AA-WBA formulated with the 8-30-mm fraction, similar to the binders activated with MK (AA-MK).
El principal subproducte generat durant la incineració de residus sòlids urbans es coneix com a cendra de fons. La seva composició és molt similars als agregats silícics naturals després d’un tractament d’envelliment on s’obté la cendra de fons madurada (weathered bottom ash; WBA segons les sigles angleses). El seu alt contingut en vidre i alumini el converteixen en un potencial candidat com a precursor en la fabricació d’aglutinants activats alcalinament (alkali-activated binders, AABs segons les sigles angleses). L’objectiu principal d’aquesta tesi doctoral va consistir en el desenvolupament de AABs mitjançant l’activació alcalina de WBA (aglutinants AA-WBA). El potencial de la WBA i els aglutinants AA-WBA es va avaluar mitjançant diferents estudis que es poden classificar en quatre blocs. Al primer bloc es va avaluar el potencial de WBA com a precursor en funció de la seva mida de partícula. Aquest estudi va demostrar el potencial de la fracció sencera i de la fracció 8-30 mm. El segon bloc es va centrar en l’estudi d’aglutinants AA-WBA que utilitzaven el WBA com a únic precursor. Es va evidenciar la influència de la concentració de la solució activadora alcalina en les propietats finals dels aglutinants AA-WBA. Els resultats van revelar la millora de les propietats mecàniques quan es va utilitzar la fracció 8-30 mm. No obstant, els resultats ambientals van revelar valors de lixiviació d'arsènic i antimoni que requerien la validació a nivell ambiental dels aglutinants. Al tercer bloc, la fracció 8-30 mm es va barrejar amb altres precursors rics en d’Al2O3 (metakaolin i PAVAL®) per millorar les propietats mecàniques i l’estabilització de metalls pesants dels aglutinants obtinguts al segon bloc. En ambdós casos, es va millorar el rendiment mecànic, tot i que les propietats ambientals van continuar mostrant valors de lixiviació que no asseguraven la viabilitat ambiental dels aglutinants AA-WBA. Finalment, al quart bloc es va realitzar una avaluació ambiental i ecotoxicològica per validar l’ús d’aglutinants AA-WBA com a material de construcció. Els resultats van mostrar un nivell mitjà-baix d’ecotoxicitat a l’AA-WBA formulat amb la fracció de 8 a 30 mm, similar als aglutinants activats amb MK (AA-MK).

Healthcare waste (HCW) incineration practices in the global South countries are among the major sources of black carbon (BC) emissions or smoke. This study analyzes HCW incineration trends during emergency situations and smoke from HCW incineration processes in Haiti. The study was prompted by the current arguments about the climate change and the growing health effects associated with BC emissions. The conceptual framework was based on both adverse health effects from BC emissions exposure and climate change potential of BC emissions. Therefore, the goal was to determine whether cardboard HCW sharps containers emit lower BC emissions to the atmosphere during the incineration process, relative to the plastic sharps containers, and the pattern of emergency HCW incineration before and after the 2010 earthquake and cholera emergencies in Haiti. This was an observational study conducted with secondary data on HCW incinerated weights from January 2009 to December 2013 and primary data on average smoke densities. Linear regression analysis of the pattern of HCW incinerated weights revealed a relatively linear pattern (R2 = 0.164) with fluctuating scenarios (peak sharp rise in 2012). Independent samples t-tests demonstrated significantly lower smoke emission during the incineration processes of cardboard sharps HCW containers as compared to plastic containers (95 % CI, p = 0.003). Implications for positive social change include provision of quantitative evidence of the benefits of cardboard sharps HCW containers in reducing smoke during incineration activities, potential data for policy formulation, suggestions for review of existing HCW guidelines, and additional research on potential health impacts of emergency HCW disposal and BC emissions.

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O exponencial crescimento populacional e a crescente urbanização, agravado pelo desenvolvimento econômico da sociedade, tem como resultado o crescimento da geração de resíduos sólidos urbanos e também a necessidade cada vez maior de energia. As formas de destinação e disposição de resíduos impactam negativamente o meio ambiente. No entanto, os resíduos podem ser utilizados para recuperação de energia, a qual pode ser adicionada à matriz do país. A realização da gestão integrada dos resíduos sólidos, com base na Política Nacional de Resíduos Sólidos, apresenta também condições para o Brasil atuar de forma responsável e com mais sustentabilidade, através de uso de instrumentos como a logística reversa e a responsabilidade compartilhada, o que pode permitir a composição gradual da hierarquia da boa gestão dos resíduos sólidos: não gerar, reusar, reciclar, destinar e dispor. O objetivo desta tese é realizar um estudo sobre um projeto regional com 39 municípios para análise comparativa para destinação dos rejeitos dos resíduos sólidos urbanos em um incinerador e disposição em um aterro sanitário com captação do biogás, considerando a possibilidade de recuperação energética em ambos os sistemas. Em complemento objetiva-se a elaboração de uma análise documental sobre o tema resíduos sólidos com abordagem de critérios que possam ser comparados entre os dois sistemas, especificamente: emissão de gases de efeito estufa, ocupação de área física de terra, impactos negativos ao meio ambiente e hierarquia dos sistemas na gestão de resíduos sólidos. Para realização deste estudo foram adotadas as seguintes metodologias: análise documental sobre os resíduos sólidos; caracterização gravimétrica das frações de resíduos sólidos produzidas na região; cálculo de captação do biogás com recuperação energética utilizando a equação elabora pelo IPCC - International Panel on Climate Change, com distribuição triangular da produção do metano gerado ao longo dos anos pela degradação lenta e rápida dos resíduos; e recuperação de energia em sistema de incineração adotando-se o valor de 500 kWh por tonelada de resíduo sólido incinerada. Assumiu-se o período de 15 anos de disposição de resíduos sólidos em aterro sanitário, mas com captação do biogás no período de 30 anos, e funcionamento do sistema de incineração pelo período de 30 anos, como forma de comparação da recuperação energética em igual período entre ambos os sistemas. Os resultados mostraram que ambos os sistemas podem produzir energia, mas o sistema de incineração tem eficiência maior em 3,2 vezes. O sistema de aterro sanitário ocupa área física de terra 18 vezes maior e emite gases de efeito estufa 2,9 vezes mais que o sistema de incineração. Ambos os sistemas causam impactos ambientais negativos, e na análise da hierarquia para a gestão dos resíduos sólidos urbanos a destinação de resíduos sólidos em incinerador é estabelecida como a penúltima opção, enquanto que a disposição em aterro sanitário é a última opção. A conclusão do estudo é que a incineração leva vantagem sobre o aterro sanitário na gestão de resíduos sólidos, porque gera mais energia elétrica, emite menos gases de efeito estufa, utiliza menos área física de terra e, por ser um sistema fechado e estanque apresenta melhores condições para mitigação dos impactos ambientais negativos.
The exponential population growth and increasing urbanization, aggravated by the economic development of society, results in the growth of urban solid waste generation and also the increasing need for energy. The destination and disposal of solid waste cause negative impacts in the environment. However, solid waste can be used for energy recovery, which can be added to the country matrix. The implementation of integrated solid waste management, based on the National Solid Waste Policy, also presents conditions for Brazil to act in a responsible and more sustainable way, through the use of instruments such as reverse logistics and shared responsibility, which may allow the gradual composition of the hierarchy of ideal solid waste management: not generate, reuse, recycle, destine and dispose. The objective of this thesis is to realize a study on a regional project with 39 municipalities for comparative analysis for the destination of waste from urban solid waste in an incinerator and disposal in a landfill with biogas capture, considering the possibility of energy recovery in both systems. In addition, the objective of this paper is to elaborate a documentary analysis on the subject of solid waste, with approach to criteria that can be compared between the two systems, specifically: greenhouse gas emissions, occupation of the physical area of land, negative impacts on the environment and hierarchy of systems in solid waste management. In order to carry out this study, the following methodologies were adopted: documentary analysis on solid waste; gravimetric characterization of solid waste fractions produced in the region; calculation of biogas capture with energy recovery using the equation elaborated by the International Panel on Climate Change (IPCC), with a triangular distribution of the methane production generated over the years by the slow and rapid degradation of the wastes; and energy recovery in the incineration system, adopting the value of 500 kWh per ton of solid waste incinerated. It was adopted the period of 15 years for disposal of solid waste in landfill, but with biogas collection over a period of 30 years, and operation of the incineration system for a period of 30 years was used as a way of comparing the energy recovery in the same period between both systems. The results showed that both systems can produce energy, but the incineration system has a higher efficiency by 3,2 times. The landfill system occupies an area of land that is 18 times larger and emits greenhouse gases 2,9 times more than the incineration system. Both systems cause negative environmental impacts, and in the analysis of the hierarchy for the management of municipal solid waste the destination of solid waste in incinerator is established as the penultimate option, while landfill disposal is the last option. The conclusion of the study is that incineration takes advantage of the landfill in solid waste management because it generates more electricity, emits less greenhouse gases, uses less physical land area and, because it is a closed system, it has better conditions to mitigate negative environmental impacts.

D’après les limites d’acceptation pour la mise en décharge des déchets, les REFIOM (Résidus d’Epuration des Fumées d’Incinération d’Ordures Ménagères) sont considérés comme déchets dangereux, car ils libèrent des quantités importantes de chlorures et de métaux lourds lorsqu’ils entrent en contact avec de l’eau. Ces solides doivent par conséquent être traités avant leur mise en décharge. A côté des traitements visant l’acceptabilité des REFIOM en décharge, quelques recherches entrevoient la possibilité de valoriser ces résidus, notamment dans des matériaux cimentaires.

Les recherches présentées ici s’inscrivent dans cette tendance nouvelle et visent l’élaboration d’un procédé combinant traitement et valorisation des REFIOM.

Les REFIOM représentent en fait différents types de résidus provenant des installations que rencontrent les fumées issues de l’incinération des déchets. La composition des résidus diffère selon leur origine. Il est dès lors apparu essentiel de considérer chaque type de résidu séparément et de poursuivre l’élaboration d’un traitement sur un seul type de REFIOM. Nous avons choisi de concentrer les recherches sur les Cendres Volantes de Chaudière (CVC), ces résidus se retrouvant dans tout incinérateur.

Le traitement des CVC est basé sur l’extraction de fractions valorisables et la séparation de fractions contaminées, permettant d’obtenir des résidus acceptables en décharge ou, idéalement eux-mêmes valorisables.

Une séparation magnétique permet d’extraire environ 10% en poids des CVC mais ne semble pas exploitable dans le cadre du traitement des CVC car les particules magnétiques contiennent des impuretés (composés non magnétiques) et que le résidu final reste contaminé.

Une étude de la répartition des éléments en fonction de la taille des particules (granulochimie) est effectuée sur les CVC. Il apparaît intéressant de séparer la fraction inférieure à 38 µm obtenue lors d’une séparation granulométrique, effectuée en voie humide en utilisant une solution dense. En effet, cette fraction semble être nettement plus contaminée en Pb (soluble) que le reste des CVC. Une telle séparation constitue dès lors la première étape du traitement des CVC. Elle est suivie par des étapes de lavage des fractions obtenues, visant à extraire les sels solubles (chlorures et métaux). Les lavages sont envisagés à contre-courant afin d’utiliser au mieux l’eau de lavage. Une recirculation interne des solutions est également prévue, de sorte que, théoriquement, le procédé ne génère pas d’effluents liquides. Une étape de précipitation de composés métalliques (PbS dans ce cas-ci) est prévue après le lavage des boues.

Le procédé de traitement des CVC produirait ainsi des boues et des granulats décontaminés, des sels et des précipités métalliques. Seules certaines étapes du procédé ont été investiguées en laboratoire ;des essais supplémentaires sont encore nécessaires pour optimiser chaque étape, comprendre les phénomènes physico-chimiques qui se produisent et assurer des filières de valorisation.

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Municipal Solid Waste Incineration (MSWI) fly ashes and Air Pollution Control (APC) residues are considered as hazardous waste according to the limits for the acceptance of waste at landfills, because high amounts of chlorides and heavy metals leach from the solids when those are in contact with water. These residues have thus to be treated before they can be accepted in landfill. Several treatments aim to limit the leaching of the residues. Beside these treatments, some research works go further the treatment and consider the valorisation of MSWI fly ashes and APC residues, e.a. in cementitious materials.

The present work follows the new trend and aims to build up a process that combines treatment and valorisation of MSWI fly ashes and APC residues.

MSWI fly ashes and APC residues come from the devices encountered by the flue gases from waste incineration. The residues composition differs according to their origin. It seems thus essential to consider each type of residues separately and to develop the treatment only on one sort of residue. Boiler Fly Ashes (BFA) were chosen because they exist in every modern MSWI plant.

The BFA treatment is based on the extraction of valorisable fractions and on the separation of contaminated fractions, which makes the final residues less hazardous; these final residues would then be acceptable in landfill, or, even better, be valorisable.

A magnetic sorting extracts ~10% (wt.) of BFA; however, such a separation would not be useful in a treatment process because the magnetic particles contain some impurities (non magnetic particles) and the final residue is still hazardous.

The repartition of the elements according to the particles size has been studied on BFA. It seems interesting to separate the BFA at 38 µm by a wet sieving process using a dense solution. The lower fraction presents a higher contamination in Pb (soluble) than the larger. Consequently, the first step of the BFA treatment consists of a wet sieving. Washing steps follow the sieving and aim to extract soluble salts (chlorides, heavy metals). These washings work in a counter-current way to optimise the use of water. The solutions are recycled in the process, which implies the absence of liquid effluents. A precipitation step of some metallic compounds (PbS in this case) is foreseen after the washing of the lower fraction.

The BFA treatment process would produce decontaminated sludge and coarse fractions, salts and metallic compounds. Some steps of the process have been investigated at lab-scale; further studies are necessary to optimise each step, to understand the observed reactions and to guarantee valorisation channels.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Les Cendres Volantes d’Electrofiltres (CVE) d’incinération d’ordures ménagères sont considérées comme des déchets dangereux et mises en décharges après une phase de stabilisation et de solidification par un liant hydraulique. Leur utilisation dans des matériaux cimentaires permet l’élimination d’un déchet en diminuant la demande de matériaux de construction. Cependant, avant leur incorporation dans des matériaux cimentaires, les CVE doivent subir plusieurs traitements. Premièrement, un lavage à l’eau permet de diminuer fortement la concentration en chlorures. Dans un deuxième temps, une séparation granulométrique des CVE est appliquée afin de ne sélectionner que la fraction la moins contaminée en métaux lourds, notamment en plomb et en zinc, ces métaux lourds étant connus comme retardateurs de prise. Enfin, une troisième étape consiste à oxyder l’aluminium métallique présent dans les CVE à l’aide d’un lavage basique à l’hydroxyde de sodium. S’il n’est pas oxydé durant la phase de traitement, l’aluminium métallique se transforme en aluminates dans la matrice cimentaire tout en produisant de l’hydrogène, responsable de l’apparition de vides et de fissures endommageant ainsi le matériau. Une fois traitées, les CVE peuvent alors être utilisées en substitution partielle du ciment pour une étude de leur réactivité potentielle. Les résultats de cette étude ont montré que l’activité des CVE traitées à l’hydroxyde de sodium est principalement d’origine physique (granulométrique et surface développée). Les CVE ne présentent pas de nature pouzzolanique. Les essais de lixiviation ont montré une durabilité équivalente et une très bonne stabilisation du chrome, du plomb et du zinc, qui permet de respecter les normes environnementales européennes./Municipal Solid Waste Incineration (MSWI) Electrofilter Fly Ash (EFA) is considered as hazardous waste and landfilled after stabilisation and solidification with a hydraulic binder. Its use in cementitious materials allows the elimination of a waste and a decrease of construction materials use. However, before its incorporation in cementitious materials, EFA has to be treated. Firstly, a water washing allows an important decrease in chloride concentration. In a second time, size-based separation is used to select the less heavy metals contaminated fraction, especially in lead and zinc. Indeed, these heavy metals are knows as setting retarders. Finally, a third step involves oxidizing of metallic aluminium contained in EFA during a basic washing with sodium hydroxide. Indeed, if it is not oxidize during the treatment, metallic aluminium converts in aluminates in the cementitious material, and produces hydrogen, generating cracking and voids, and damaging the cementitious material. After the treatment step, a study of the potential reactivity of EFA used in partial replacement of cement is carried out. Results show the activity of EFA treated with sodium hydroxide is mainly physical (grading and developed surface). EFA presents not pozzolanic effect. Leachability tests show an equivalent durability and a very efficient stabilisation of chrome, lead and zinc, allowing the respect of the European environmental standard.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Thesis (MPhil)--Stellenbosch University, 2003.
Full text to be digitised and attached to bibliographic record.
ENGLISH ABSTRACT: The Tsitsikamma Forest, in the most southern part of the Eastern Cape, is part of the Cape Floral Kingdom, one of six such Kingdoms in the world. It has the richest area of plant bio-diversity and fauna in the world which are rare and endemic to the area. The deep gorges, temperate forests, un spoilt oceans and various other features such as the famous Bloukrantz River Bridge, where the world's highest bungi jumps take place are factors that have become the main source of job-creation and income for tourism and its inter-related activities. However, this ecosystem is also home to about 480 families who live in low-income housing at Stormsriver. This settlement which was relocated from the shack area of Coesa, nearby, has an unemployment index of 67% and a similar poverty index. In addition, the Stormsriver Village nearby has a population of about 300 families, mainly older retired white folks. The area is administered by the Koukamma Municipality which is an amalgam of several smaller municipalities viz., Clarkeson, Kareedouw, Stormsriver, Woodlands, Eerste River, ]oubertina and Bloukrantz. Waste reduction and the disposal thereof has always been a major concern to local authorities and the Koukamma Municipality is obviously faced with the same challenge. The authorities have resorted to the concept of landfill sites, which has proven to be the cheapest solution to date. But, with this option comes the problems of health risks to the poorer people who converge on the dump sites in search of food, the harm to children searching through rubbish heaps and the various legal repercussions emanating out of this practice. The option of open-burning and its related effects on human life and forest fires rules it out as an option. Transporting waste out of the area is also very costly. It was then resolved by the Koukamma Municipalities that the possibility of installing an incinerator at Stormsriver would be an option to be investigated. The reasoning behind the selection of this site was the concern of high unemployment in the Stormsriver area and extreme poverty and this venture would in some small measure create jobs, put food on the table and break the poverty cycle. The process of incineration gives rise to emissions such as dioxins and furans which is known to cause cancer, asthma and tuberculosis, if subjected in high doses over a long period of time. It is also regulated by the Atmospheric Pollution Act 45 of 1965. The important moral debate at the core of this problem is the whole question of humans rights and should these be violated solely because the subjects do not belong to an affluent class and should be shown less respect and have their health jeopardised by the toxic air from incineration. Or, should the people's poverty index rise further due to lack of employment. The question that also begs here is whether the well-being of the entire ecosystem, especially the rare and endangered plants and animals take preference over the well-being of the people of Stormsriver, given that the emissions from the incinerator will impact on the animal, bird and plant life, including that of water, soil and air. This would also put into jeopardy the income generated by Tourism and the jobs inherent in it for the locals and would threaten the area's sustainability. The various moral views of philosophers have been canvassed in order to come to a holistic understanding. I have in this vein looked at the views of ethicists such as Tibor Machan, who believes that animals and other organisms do not have any rights and are there purely for human consumption. Then the views of Peter Singer and Tom Regan have also been included, in which consideration is shown to animals. Others such as AIda Leopold, J. Baird Callicott and Paul Taylor whose thinking extends to that of not just showing respect for a single entity but allows for equal respect for all members of the biotic community, have also been. considered. Various solutions have thereafter been considered and amongst those are the relocation of the incinerator out of the Stormsriver, moving the plant to the industrial zone at Kareedouw, transporting the waste out to Port Elizabeth, dumping and finally the 'Do Nothing' option. Using Paul Taylor's "respect for nature" ethics as a guide, I have come to the conclusion that the installation of a waste-reduction incinerator at Stormsriver, Tsitsikamma, may be supported subject to a set of serious riders and conditions in that firstly, the health of the immediate and surrounding inhabitants should not be affected in any way whatsoever. Secondly, the well-being of the non-human environment which must include air, soil, water and plant life, including the animal and bird life must not be harmed in any way. In this way all members of the biotic community will be shown equal respect, thus creating a viable and sustainable community
AFRIKAANSE OPSOMMING: Die Tsitsikamma Woude, in die mees suidelike deel van the Oos-Kaap, is deel van die "Cape Floral Kingdom", een van ses sulke woudgebiede in die wêreld. Dit beskerm die rykste area van plant bio-verskeidenheid asook fauna wat skaars is in die wêreld en slegs daar gevind word. Die diep bergpasse. gemagtigde woude en ongerepte oseaan, tesame met die beroemde Bloukransrivier brug waar die wêreld se hoogste bungi spronge plaasvind is faktore wat bygedra het dat werkskepping en inkomste hoofsaaklik uit toerisme en verwante bedrywe afkomstig is. Hierdie eko-sisteem is ook die tuiste vir ongeveer 480 gesinne wat in sub-ekonomiese huise in Stormsrivier woon. Hierdie gemeenskappie wat vanaf die naby geleë Coesa hervesig is, het 'n werkloosheid sowel as armoede syfer van 67%. Bykomend is daar die Stormsriver nedersetting daar naby met 'n bevolking van 300 families, hoofsaaklik ouer, afgetrede blankes. Die gebied word bestuur deur die Koukamma Munisipaliteit wat in 'n samesmelting van 'n hele paar kleiner munisipaliteite is o.a Clarkson, Kareedouw, Stormsrivier, Woodlands, Eerste Rivier, ]oubertina en Bloukrans. Die vermindering van afvalstowwe asook die verwydering daarvan was maar altyd 'n groet kopseer vir die plaaslike owerhede en dit geld nou ook vir die Koukamma Munisipaliteit. Die owerhede het besluit op die konsep van afvalstortings areas omdat dit die goedkoopste oplossing tot nou toe is. Met hierdie opsie kom egter die probleem van gesondheids risiko's vir die armer gemeenskappe (mense) wat op hierdie stortings terreine toesak op soek na kos, die beserings wat kinders opdoen wat die gemors deursoek asook die wettige terugslag wat hierdie praktyk totgevolg het. Die gevaar van oop vure en die effek wat dit sou hê op mense en die woud self maak dat hierdie opsie nie oorweeg word nie. Ook is dit te duur om afvalstowwe uit die gebied uit te vervoer. Die Koukamma Munisipaliteit het toe besluit om die instállering van 'n verbrandingsoond by Stormsrivier te ondersoek. Die rede om hierdie gebied te kies was die hoë werkloosheid syfer en armoede in Stormsrivier. Hierdie besluit sou werkskepping, kos op die tafel en die verbreking van die armoede-siklus tot gevolg hê. Die proses van verbranding het aanleiding gegee tot die nuwe gevare van skadelike afval produkte van dioksiede en furane wat kanker, asma en tuberkulose tot gevolg het as mense vir lang periodes aan hoë dosisse blootgestel word. Hierdie uitstraling word ook deur die "Atmosferiese Besoedelingswet 45 van 1965" gereguleer. Die belangrike morele debat wat die kern van hierdie probleem vorm is die vraag na menseregte en of die menseregte geskend kan word bloot omdat die mense in die gebied nie aan 'n gegoede klas behoort nie moet daar minder respek aan hulle getoon word en moet hul gesondheid in die weeg skaal geplaas word deur die giftige lug as gevolg van die verbrandering van afvalstowwe, of moet werkloosheid verder styg as gevolg van die gebrek aan werk? Die ander vraag wat gevra moet word is of die welvaart van die hele ekosisteem, veral die van skaars en bedreigde plante en diere voorkeur moet geniet bo die welvaart van die mense van Stormsrivier gegee die feit dat die uitstraling van die verbrandingsoond ook 'n inpak gaan hê op die diere, voëls en plant lewe inkluisend op water, grond en lug. Dit sal ook die inkomste wat uit Toerisme voort gebring word, en die werksgeleenthede vir die plaaslike mense wat daarmee gepaard gaan, in die weegskaal plaas asook die gebied se standhoudendheid bedreig. Die verskeie standpunte van filosowe is na gekyk ten einde tot 'n holistiese verstaan van die situasie te kom. Langs hierdie weg het ek dan na die etiese standpunt van Tibor Machan gekyk. Tibor Machan glo dat diere en ander organismes geen regte het nie en dat hulle daar is vir die uitsluitlike gebruik deur mense. Die standpunte van Peter Singer en Tom Regan, wat 'n mate van sorgsaamheid teenoor diere toon, is ook in ag geneem. Andere wie se standpunte in ag geneem is, is Aldo Leipold,J. Baird Callicot and Paul Taylor. Hulle denkrigting maak voorsiening daarvoor dat respek nie net aan 'n enkele entiteit getoon moet word nie, maar aan almal wat in 'n biotiese gemeenskap saamwoon. Verskeie oplossings is hierna oorweeg onder andere die verskuiwing van die verbrandingsoond buite Stormsrivier na die industriële gebied in Kareedouw, die vervoer van die afval na Port Elizabeth, storting asook die "Doen Niks" opsie. Ek het as etiese riglyn Paul Tayor se "respekteer vir natuur" gebruik en het tot die slotsoom gekom dat die iristallering van 'n afval verminderings verbrandingsoond te Stormsrivier ondersteun kan word met ernstige voorbehoude en voorwaardes deurdat, eerstens, die gesondheid van die onmiddelike en omliggende inwoners op geen manier hoegenaamd aangetas moet word nie. Tweedens, die welvaart van die nie-lewende omgewing met inagneming van lug, grond, water en plantlewe, insluitende die diere en voëls moet op geen manier geskaad word nie. Op hieride maruer sal almal wat deel uitmaak van die biotiese gemeenskap gelyke respek betoon word wat die daarstelling van 'n lewensvatbare en standhoudende gemeenskap tot gevolg sal hê.

Municipal solid waste management (MSWM) is a global problem as most local authorities fail to dispose MSW safely. In view of this, the study was aimed at evaluating environmental and health risks associated with municipal solid waste (MSW) illegal disposal as well as constraints faced by Masvingo City in MSWM, with a view to developing an alternative sustainable management model. The study, informed by the philosophy of pragmatism, employed a mixed methods design in which quantitative and qualitative data werecollected concurrently. Questionnaires comprising both close and open-ended questions, semi-structured interviews and site visits were used to collect data. The study population comprised participants from Masvingo City’s residential areas, Masvingo City Council employees, Environmental Management Agency (EMA) officials and informal waste pickers. A sample of 406 participants, comprising 354 residents from high-density, 16 residents from medium-density, 24 residents from low-density suburbs, six council employees, two EMA officials and four informal waste collectors participated in the survey. Concurrent triangulation was employed to analyse data. Basic numerical analysis was used for quantitative data while thematic data analysis was employed for qualitative data. Three main findings which emerged from the study were (a) Land pollution, air pollution, surface water pollution and loss of urban beauty, were the main environmental risks as at least 59 % of the respondents noted the four as environmental risks associated with illegal municipal solid waste disposal (b) Cholera, skin problems and malaria were the main health risks; and, (c) The main constraints related to MSW management were inadequate environmental education, lack of cooperation and participation from waste generatorsand lack of resources by Masvingo City . From the findings, 66 %, 52 % and 49 % of participants noted inadequate environmental education, lack of cooperation and participation, and lack of resources respectively as constraints faced by Masvingo City in MSWM. Basing on the findings of the study, it can be concluded that MSW disposal in Masvingo was a threat to the environment and human health and, as a result, a sustainable MSWM model was developed for Masvingo City.
Environmental Sciences

Chemical and allied industries produce significant quantities of chlorinated wastes each year. Thermal treatnent of these chlorinated wastes has a long and controversial history. The most common and contentious method of waste destruction is incineration. Although waste incinerators are designed to provide greater control over the combustion process, toxic products are inevitably formed from incomplete combustion and released in stack gases and other residues. The most notable group belonging to the products of incomplete combustion (PICs) are dioxins and furans. The fact that oxygen is an integral part of the molecular structure of dioxins and furans suggests that the formation of these particular PICs may be reduced or avoided by minimizing or completely excluding oxygen from thermal waste treatment. Pyrolysis using induction heating is a relatively new technology that has shown much promise from the initial work performed by Pillay (2001). This research was an extension of that study, and investigated equipment and process optimization as well as macroscopic modeling of different systems. The objective of this study was to establish the technology of pyrolysis using induction heating as a competitive alternative to existing waste destruction systems. The novel approach of pyrolysing compounds using induction heating was demonstrated by destroying chlorinated aliphatic, aromatic and a mixture of these compounds. These experiments were conducted at atmospheric pressure in a tubular laminar flow reactor (5.2cm I.D) under a thermally transparent argon atmosphere. In this system heat was generated in an embedded graphite tube using induction heating. Thermal degradation occurred through the bombardment of the compounds by the photons emitted from the heated graphite tube. The compounds were pyrolysed at temperatures ranging from 330°C to 1000°C and at mean residence times from 0.47s to 2.47s. In addition to these process variables the effects of reactant concentration and additives were investigated The major species formed from this thermal treatment were solid carbon black and gaseous hydrogen chloride. Destruction efficiencies (DE) of the order of 99.9999% (six nines) and greater were obtained for the different feed mixtures at their respective operating conditions. A minimum DE of six nines adequately satisfies the regulation set by the Environmental Protection Agency (EPA) for successful waste destruction.
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2004.

The absence or unavailability of solid waste disposal facilities and service in rural areas of the UThukela District Municipality (UTDM) compelled residents to adopt many disposal practices. This included open burning of waste, which leaves residues in the form of waste ashes. Some heavy metal and hazardous substances remain active in these waste ashes. In this study, the impact of Solid Waste Disposal Practices (SWDP) on the environment was investigated by evaluating the effect of waste ashes on plant growth. The research was directed towards the evaluation of the environmental impact of solid waste disposal practices by households in these rural areas of KwaZulu-Natal (South Africa), on the growth of Zea Mays (Maize) plants. Rural maize farmers dominate the district of UTDM because it is a good agricultural area with great potential for high rainfall in summer, moderate temperatures, good soil and moderate slopes. The method selected to achieve research objectives was the evaluation of the influence of waste ashes, as by-products of SWDP, on plant growth. This was achieved by, determining soil fertility; collecting household solid waste from different rural families to determine the composition (including already burnt ash, plastic ash and wood ash; analysing the chemical composition of traditional ashes collected from sites where it was burnt (waste ashes); applying the evaporation pan test; mixing waste ashes and other additives with soil in planting pots in equal parts; planting Zea Mays in winter and summer; and lastly, monitoring and measuring agronomic parameters of plant growth on a regular basis. The selected additives to the in situ soil were fertilizer, compost, waste ash, plastic ash and wood ash. Pots with soil only (no additive added) served as control. The findings revealed that plants exposed to wood, waste and plastic ash struggled to grow when compared to plants grown with fertilizer, compost and soil only. The impact of all waste ashes on plant growth was negative in both seasons and some of the agronomic parameters were unable to sprout during the course of plant growth. The chemicals found after analysing the waste ashes included some of the heavy metals that remained active after burning. These were left behind in the environment. Consequently, it was concluded that household solid waste disposal practices in rural areas should be reviewed urgently, as they affect plant growth negatively. Recommendations were provided.
Environmental Sciences
M. Sc. (Environmental Science)