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Recycling - from waste to resource: assessment of optimal manual dismantling depth of a desktop PC in China based on eco-efficiency calculations

TitleRecycling - from waste to resource: assessment of optimal manual dismantling depth of a desktop PC in China based on eco-efficiency calculations
Publication TypeThesis
Year of Publication2007
AuthorsGmuender S
Academic DepartmentDepartment of Environmental and Geomatic Engineering / Technology & Society Lab
UniversitySwiss Federal Institute of Technology (EPFL) / Swiss Federal Laboratories for Materials Testing and Research (Empa)
CityZurich / St.Gallen Switzerland
Thesis TypeMaster Thesis
Abstract

The main strength of the Chinese e-waste recycling system is the efficient manual preprocessing, which is the basis for a high material recovery rate. However, primitive and hazardous processes are applied frequently when it comes to the actual recovery of complex materials, such as printed wiring boards (PWBs). Therefore an alternative recycling system is developed substituting the primitive further processing with the best available technology (BAT), which is presently only available in industrialised countries. The main aim of this study is to optimize the interface between manual pre-processing and further treatment by assessing the optimal dismantling depth. The focus lies on desktop PCs, as well as on sublevel devices in a PC such as disk drives and power supply. Different dismantling scenarios under an environmental and economic perspective are assessed and compared to mechanical pre-processing. The determination of the environmental impact is based on Life Cycle Assessment (LCA), while for the economic analysis the Life Cycle Costing (LCC) methodology is applied. Further, the two-dimensionally assessed scenarios are interpreted according to their total eco-efficiency. The results show that environmental weighted recycling percentages increase from 70% to 84% when the complete manual-dismantling scenario is compared with the shredding. The further processing is identified to contribute most to the total environmental gain, while causing only a minor environmental burden. The pre-processing and the transportation are negligible from an environmental perspective. For one desktop PC, the net financial result increases from 4.40 Euro per unit revenue to 8.30 Euro, including all costs for collection, sorting, transport and further treatment considering average metal prices as of February 2007. The partial dismantling of the desktop PC into its main sub assemblies such as drivers, main boards and encasing shows that an environmental weighted recycling rate of 79% and a net revenue of 5.90 Euro per unit. Therefore this study concludes that high level manual dismantling is economically and environmentally preferable to a mechanical pre-processing under Chinese settings.

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