Eco-efficiency assessment of options for metal recovery from incineration residues: a conceptual framework.

Residues from municipal solid waste (MSW) incineration in Switzerland have been a hot topic in recent years, both in the research and practice communities. Regarded by many as an economically and environmentally sound solution to this issue, technological retrofitting of existing grate incinerators has the dual purpose of enhancing the metal recovery of bottom and fly ashes and improving the inertization of residues to be landfilled. How does context influence the economic and environmental performance of this particular technological option? Under which conditions would this technological option be implemented nationwide in the future? What are stakeholders' views on sustainable transitions of MSW incineration? We propose a three-stage methodological procedure to address these questions.

Technological change in Swiss thermal waste treatment: an expert-based socio-technical analysis.

Understanding technological change provides a crucial basis for governing sustainability transitions. In this paper we present an analysis of technological change using the example of Swiss thermal waste processing. In recent years, increased concerns about the low quality of residues from grate-firing systems led to the examination of alternative technologies. Yet despite clear indications of a potential better performance with respect to residue quality, none of these alternatives has been adopted. Based on a two-stage knowledge integration among 15 leading experts, in a retrospective analysis we identified factors that have significantly affected technological change in Swiss thermal waste processing. These factors were then related to three technological options representing different types of technological change, i.e., from incremental improvements of the existing to the implementation of a new technology. The results indicate that technological change is currently in a technological lock-in and provide detailed insights on the causes. The lock-in results in the step-wise further development of the status quo grate-firing system despite its limitations for improving the residue qualities. Almost all factors (legal, economic, societal, technological) of the existing 'thermal waste management' system have been well adapted to the cost- and energy-efficient grate-firing technology, blocking innovative technologies from entering the Swiss market. In addition, pressures from the context, e.g., societal pressure related to landfill risks, have not been strong enough to promote non-incremental change.