Thermal recycling of household waste generates slag which has to be disposed of in special landfill sites. SELFRAG (in Kerzers, Canton of Fribourg) uses an innovative high-voltage electrical process to reclaim the metals and other valuable recyclable materials from this slag, thereby reducing the amount of waste generated.

“Ideally, we would like to be able to treat waste so efficiently that we can reclaim all the source materials, thereby generating zero waste.” This is the ultimate goal of Frédéric von der Weid and his company SELFRAG, a 2007 spin-off of the Langenthal-based Ammann Group that today employs a workforce of 30. The company has industrialised a process that uses pulses of high-voltage electricity to break down materials into their component parts. “Our process works in the same way as a bolt of lightning splitting a tree,” explains CEO Frédéric von der Weid, drawing a graphic comparison.

Up to now, high-voltage disaggregation has only been used to any great extent in research and the semiconductor industry. For these applications, the Fribourg-based company has already sold more than 40 installations worldwide. SELFRAG’s bosses now see the future key application of this technology as being in the waste-processing industry, because almost 100% of metals and low-polluting construction waste can be reclaimed from slag using this high-voltage process.

The slag produced by incinerating household waste contains a number of valuable materials: one tonne of waste contains on average 7 kilograms of valuable copper, for example. The SELFRAG process makes it possible to recycle these kinds of high-worth materials and at the same time reduces the quantity of slag by around a quarter. In the future, Frédéric von der Weid thinks it will be possible to cut the amount of slag by as much as half.

This environmental technology has been in use at the waste incineration plant in Posieux near Fribourg since spring 2017, and SELFRAG plans to sell more installations in Switzerland. There are important export markets for this technology in Germany, Scandinavia and the US. In all these countries, most or at least some household waste is incinerated and not disposed of in landfill, as it is in Brazil and China for example.

SELFRAG’s business model is based on selling installations and operating them in-house. It is also looking at processing slag already in landfill to reclaim the valuable materials it contains and create additional space on landfill sites that are already over capacity.