Municipal waste incineration plants (MWI)

Combustible waste from households and waste wood that is not suitable for recycling undergo thermal treatment in waste incineration plants or waste wood furnaces. The heat released in the process is used to generate electricity and heat buildings.

Recovering metals from waste incineration plant slag – An industry in transition

Conference of the Waste and Resources Division of the Federal Office for the Environment, 29 September 2023, Ittigen

Every year, around 4 million tonnes of waste are incinerated in Swiss waste incineration plants. In addition to heat recovery and electricity generation, incineration residues are becoming an increasingly important focus for waste incineration plants in the circular economy, due to their metal content. At the conference, representatives from the University of Bern presented their research and the operators of the plants involved in the project reported on their practical experiences.

Key findings of the project:

All facilities comply with the limits set by the Waste Ordinance
Even the best processes can only recover about 50% of the metals from incinerator slag; about 50% still ends up in landfills along with the mineral residues
The metal yield varies for the metals aluminium, copper, zinc and lead, ranging from around 70% for aluminium to 10% for lead (based on the initial metal content)
Further technical improvements in this technology seem unlikely at present, as the additional shredding and recovery effort is economically and environmentally suboptimal