Rethinking incinerator bottom ash

When municipal waste reaches waste handling facilities, it is mechanically sorted into different streams: paper, PET bottles, plastics, metal. The waste that cannot be mechanically sorted is burnt in incinerators. End of story? Not necessarily. Treasures can be found in the incinerator bottom ash.

When trash is taken to waste-handling facilities for incineration, the organic part of the waste burns and ideally you capture the energy and the CO2 that comes from the smokes to make new materials like plastics. You are left with bottom ash, a mix of unorganic waste, minerals and metals.

"There are lots of metals in the bottom ash that can be recovered for further use", says Niklas Törnkvist, founder and CEO of Magsort.

Magsort's solution consisting of a crusher and magnetic technology can recover more metals compared to other options on the market, giving customers up to three times more revenue in form of metal sales.

Finnish energy company Fortum has three of Magsort's solutions in various waste-handling facilities in Finland and Sweden. Kalle Saarimaa, Vice President, Recycling and Waste Solutions at Fortum, explains why.

"Magsort's technology is superior when it comes to recovering metals from the bottom ash."

Saarimaa would like society to rethink incineration's bad reputation.

"It is largely seen as a failure in the circular economy. But treated in the right way, incineration is not the end of a linear development, but an important step in achieving full circularity", he says.

He is especially keen on seeing the bottom ash residual after recovery of the metals be put to good use. What is left of the bottom ash once metals have been recovered by Magsort's solutions, can be used instead of cement in the production of concrete. Currently, cement is produced through calcination, a process where you expose raw materials such as limestone to high temperatures. Replacing the calcination process with bottom ash would dramatically decrease CO2 emissions.

Saarimaa sees an important role for Magsort in the circular economy.

"To achieve circularity, we need a lot of niche players who are really good at what they are doing. Magsort has found their spot."