Text in English / The study focused on the characterisation and management of non-formal solid waste disposal sites in Harare, the capital city of the Republic of Zimbabwe. In many developing countries, increasing urbanisation surpasses the development of urban infrastructure and this has led to the proliferation of informal settlements, illegal dumping sites and uncontrolled vending in cities like Harare. The researcher investigated the prevalence of non-formal dumping sites in Harare, including the composition, locational attributes and internal linkages of solid waste. Practices regarding the management of non-formal solid waste disposal sites were examined and areas of good practice and conformity to international standards were complemented while recommendations and suggestions were made on areas that were found wanting. An integrated management system was recommended for the sustainable management of solid waste. To support this recommendation, management window of responsibilities (EMWR) model was created so that the Harare City Council can enhance stakeholder participation. The research results show that most residents used non-conventional ways to store waste, like mealie-meal bags and sacks, and this posed a danger to human health. It also emerged that the city of Harare has not updated some of its by-laws, some of which were enacted about 33 years ago while others remained drafts for decades. This made it difficult for the city to effectively implement them. / Environmental Sciences / M.Sc. (Environmental Management)

Ce travail est le résultat de recherches réalisées d’abord dans le cadre d’un programme d’archéologie préventive (2001-2004), puis d’une bourse doctorale à l’ULB entre 2004 et 2010 (Introduction générale). Les sites étudiés sont localisés dans la région de Kribi (côte camerounaise) et sont essentiellement composés de fosses, qui sont très certainement les vestiges des premières entités villageoises ayant habité la zone forestière atlantique du Cameroun vers ca. 3000BP (Chap. 1). La méthodologie adoptée varie sensiblement selon les deux programmes (Chap. 2). Le matériel analysé, surtout la céramique (Chap. 3, 4 et 5), a été récolté au cours des fouilles de sauvetage et programmées et a permis de définir une chronoséquence générale entre ca. 1000 BC et ca. AD 1000 (Chap. 6) qui comprend trois traditions céramiques :la Tradition de Bissiang (période de Transition Âge de la Pierre/Âge du Fer, Cal 1000-400 BC), le Groupe de Mpoengu (Âge du Fer I, Cal 400-50 BC) et la Tradition de Bidjoka (Âge du Fer II, Cal AD 0-1000). Cette dernière tradition est aussi contemporaine de l’apparition de sociétés complexes sur la côte méridionale camerounaise et ses environs, dont les sites se caractérisent surtout par la présence de ce qui semble être des structures funéraires, dans lesquelles on trouve de nombreux objets en fer (parures, armes, etc.) disposés de manière particulière et généralement associés à de poteries carénées décorées.<p>Une étude comparative de la chronoséquence de la zone côtière a été faite avec celles déjà établies pour les zones avoisinantes, notamment au centre du Cameroun et dans les pays voisins (Chap. 7). Ce rapprochement a permis de conclure, entre autres, à une parenté culturelle entre la Tradition de Bissiang et celle d’Obobogo identifiée dans la région de Yaoundé (zone de forêt mixte). Enfin, l’ensemble des études comparatives a aussi conduit à faire quelques spéculations sur le peuplement de l’Afrique Centrale forestière depuis environ 3000 BP (Conclusion générale). <p> / Doctorat en Histoire, art et archéologie / info:eu-repo/semantics/nonPublished

MESHWR / Department of Hydrology and Water Resources / This research involves the investigation of the interaction of different sized Nano Gold particles released into municipal drinking water and municipal waste water. Waste water was collected from Malamulele waste water treatment plant and the municipal water was collected at Mintek in Johannesburg, Randburg, South Africa. The waste water was analysed using ICP-MS to detect the metals and anions in it. The results showed the abundance of Sulphur (464 ppm), Calcium (28 ppm), Chloride (27.8 ppm), Iron (20 ppm), Magnesium (8.2 ppm), silicon (6.192 ppm) in descending order and other trace elements, including gold, that were immeasurable (<0.1). The simulated situation was created by adding 20nm gold and 40nm gold nanoparticles into municipal drinking water and waste water and kept at different environmental conditions (light, light and agitation, dark, dark and agitation) under aerobic and anaerobic conditions over a period of two months. Physico-chemical properties (pH and chemical oxygen demand) of the solutions were checked once in a month. The pH fluctuated between the acceptable ranges (5.5 – 9.5) for the two month period. Both municipal water and waste water, with and without gold nanoparticles, under aerobic condition showed an increase in chemical oxygen demand. The gold content in waste water under anaerobic condition showed an increase while under aerobic condition the decline in gold content was evident. The zeta potential of gold nanoparticles in waste water in light and agitation showed (-30 mV) while waste water on other environmental condition (light, dark and dark with agitation) presenting unstable (-18 mV) charge, but the charge shifted positively on the second month rendering them also unstable. Dynamic light scattering and TEM were used to check any possible aggregation or agglomeration of nanoparticles in the waste water. There were some few discrepancies where TEM and DLS contradict, but overall there was no significant probability of any aggregation of gold nanoparticles. The EDX was used to confirm the presence of Au0 in the waste water (with added gold nanoparticles). The research did show that the gold nanoparticles would exist as Au0 in the waste water and thus the discharge of Au-NPs to the sewer system is not recommended, but rather recycle them.

Indiana University-Purdue University Indianapolis (IUPUI) / Peripheral arterial disease is caused by plaque buildup in the peripheral arteries. Standard treatments are available when the blockage is proximal and focal, however when distal and diffuse the same type of the treatment options are not beneficial due to the diseased locations. Restoration of blood flow and further salvaging of the limb in these patients can occur in a retrograde manner through the venous system, called retroperfusion or arteriovenous reversal. Retroperfusion has been explored over the last century, where early side to side artery to venous connections had issues with valve competency prohibiting distal flows, edema buildup, and heart failure. However, more recent clinical studies create a bypass to a foot vein to ensure distal flows, and though the results have been promising, it requires a lengthy invasive procedure. It is our belief that the concerns of both retroperfusion approaches can be overcome in a minimally invasive/catheter based approach in which the catheter is engineered to a specific resistance that avoids edema and the perfusion location allows for valves to be passable and flow to reach distally. In this approach, the pressure flow relations were characterized in the retroperfused venous system in ex-vivo canine legs to locate the optimal perfusion location followed by in-vivo validation of canines. Six canines were acutely injured for 1-3 hours by surgical ligation of the terminal aorta and both external iliac arteries. Retroperfusion was successfully performed on five of the dogs at the venous popliteal bifurcation for approximately one hour, where flow rates at peak pressures reached near half of forward flow (37±3 vs. 84±27ml/min) and from which the slope of the P/F curves displayed a retro venous vasculature resistance that was used to calculate the optimal catheter resistance. To assess differences in regional perfusion, microspheres were passed during retroperfusion and compared to baseline microspheres passed arterially prior to occlusion in which the ratio of retroperfusion and forward perfusion levels were near the ratio of reversed and forward venous flow (0.44) throughout the limb. Decreases in critical metabolites during injury trended towards normal levels post-retroperfusion. By identifying the popliteal bifurication as a perfusion site to restore blood flow in the entirety of the distal ischemic limb, showing reversal of injury, and knowing what catheter resistances to target for further chronic studies, steps towards controlled retroperfusion and thus more efficient treatment options can be made for severe PAD patients.

Les rejets des Usines à Zinc de Kolwezi contiennent majoritairement du zinc sous forme réfractaire (ferrite) au traitement hydrométallurgique conventionnel. Ils contiennent d’autres métaux « lourds » qui les rendent dangereux vis-à-vis de l’environnement dans lequel ils sont actuellement entreposés. Ces métaux, dont la plupart peuvent être valorisés, font de ces rejets un véritable gisement secondaire. Il est donc impératif de mettre au point un procédé adéquat de valorisation ;d’où le thème de la présente thèse :« Etude de valorisation des rejets des Usines à Zinc de Kolwezi, RDC ». <p>A l’aide des techniques modernes de caractérisation (physico–chimique, minéralogique et morphologique), nous sommes arrivés à cibler, à adapter et à justifier l’utilisation d’une technique de valorisation des matières minérales existantes. Les minéraux utiles contenus dans les rejets UZK ont été sulfatés par digestion et sélectivement mis en solution après un grillage. La sulfatation s’est avérée l’étape déterminante du procédé et un intérêt particulier a été focalisé sur cette étape en réalisant une étude cinétique approfondie.<p>Les données et informations récoltées tout le long de cette recherche nous ont permis de réaliser une simulation du procédé par le logiciel ASPEN PLUS. Ce qui a permis de faire une ébauche d’un schéma de traitement industriel. Ce dernier s’est avéré souple vis-à-vis de l’utilisation d’autres matières comme les calcines des concentrés sulfurés cuivre-zinc.<p><p>Residues from the Kolwezi Zinc Plant (Usines à Zinc de Kolwezi UZK) essentially contain zinc in a refractory (ferrite) form, which is difficult to recover by conventional hydrometallurgical methods. « Heavy» metals are also present that make them hazardous towards the environment in which they are currently stored. Most of these metals are valuable; thus, the UZK residues are a real secondary deposit. It is therefore imperative to develop an appropriate method of treatment, hence the theme of the present thesis: « Recovery study of values metals from Kolwezi Zinc Plant residues, DRC ».<p>Using modern techniques of characterization (physical and chemical, mineralogical and morphological), we focused, adapted and justified the use of a technique for efficient recovery of the existing valuable minerals. The minerals contained in UZK residues have been sulphated by digestion and thereafter selectively dissolved after roasting. Sulphatation proved to be the decisive step of the process and a particular attention has been given to this step by performing a detailed kinetic study. <p>The data and information collected throughout this research allowed a simulation of the developed method by using the « Aspen Plus » software. This allowed us to propose a draft scheme of industrial processing. The latter proved flexible towards the use of other materials such as calcines of copper-zinc sulphide concentrates.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished