Browsing by Author "Bigirwa, D."
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Item Capturing household preferences on solid waste management services in urban areas of developing countries(Scientific Publishing Group, 2017) Bigirwa, D.; Mombo, F.Solid waste generation is an increasing global problem. The problem is more pronounced in developing countries due to experienced budget constraints and lack of strong institutions in the management of waste collections and disposals. Local government authorities in Tanzania have made efforts to ensure proper solid waste management especially in urban areas. Despite these initiatives solid waste management is still a key environmental problem in most urban areas of the country. This may be due to non-inclusion of household preferences on solid waste management when designing solid waste management services. A Choice Experiment Method was used in this study to determine household preferences on solid waste management services in order to design sustainable solid waste management services in Kinondoni municipality. The results showed that both low and high income households in Kinondoni Municipality prefer solid waste management services. The mostly preferred solid waste management service attributes were frequency of solid waste collection and use of vehicles while provision of polythene bags attribute was not preferred by households. The findings showed that are high variations in household preferences for solid waste management services caused mainly by socio-economic characteristics such as income. In order to improve solid waste management in Kinondoni municipality, policy makers and solid waste management service providers should incorporate household preferences on solid waste management services when designing these services.Item The role of Sub-Saharan Africa Countries’ households waste charges on sustainable cities development(International Journal of Waste Resources, 2017) Mombo, F.; Bigirwa, D.The increasing use of rare earths elements (REEs) in a number of recent technological innovations led to a rapid increase (>50% in the last decade) in their applications. Europe is one of the most important regions of consumption of these substances. In this context, Europe in its 'Raw materials' strategy puts the recycling at the center of its concerns to provide a part of securing its supplies in REEs. Recycling of these substances, on an industrial scale, remains somewhat developed while it presents numerous advantages over the exploitation of primary resources. This paper will present some results obtained from characterization study of permanent magnets (PMs) present in WEEEs. Three components containing PMs are identified: hard disk drives, small electric motors and speakers. The representative sample of these components has been dismantled manually to recover the PMs contained and to quantify their amount. The results show that the weight percentage of the PMs varies from 4 to 6% in the speakers, 2.5 to 2.8% in the hard disks, and between 0.8 and 2% in some electric motors. The results of the thermal treatment of the Nd-Fe-B PMs of the investigated samples show that the majority of these PMs lose their magnetic property upon reaching Curie temperature (300-400°C) in 15-20 min. Scanning Electronic Microscopy reveals the morphological aspects of the PM which consist in crystals shaped tetrahedral phase Nd2Fe14B sintered in the presence of the interphase rich in Nd, Dy and Pr. The PM are layer coated with 20 µm thick, consisting of Ni, Zn or metals alloys.