Environmental systems analysis of the use of bottom ash from incineration of municipal waste for road construction

摘要

Bottom ash, originating from municipal solid waste incineration (MSWI), may be used as road construction material. This would mitigate disposal problems, and at the same time reduce the extraction of rock material. The aim of this study was to describe what differences in environmental impacts that can be expected if crushed rock in the sub-base of a road in the Stockholm region in Sweden is substituted by MSWI bottom ash, taking into account the whole lifecycle of the road and including alternatively disposal of the bottom ash. Tested scenarios for sub-base material in a theoretical road were crushed rock (alternative 1) and MSWI bottom ash (alternative 2). The study was performed as an environmental systems analysis and based on a life cycle approach. Data was gathered for the major resources used and the environmentally hazardous emissions formed in those life cycle stages that differed between the two scenarios. The results indicate that both the consumption of resources and the release of emissions from the system would be biggest in alternative 1. The formation of emissions depends on the amount of energy used during the different life cycle stages. The greatest differences between energy uses in the two alternative systems derive from production of crushed rock and from landfilling of MSWI bottom ash. The results are preliminary and further work is planned for improvement of data quality and inclusion of heavy metal leaching from the road material.