Bio-mining from Lusatia: BTU develops recycling process with bacteria and CO₂

"We are transferring a biological process known from ore mining specifically to secondary raw materials from electronic waste," explains Prof. Dr Christian Abendroth, Head of the Chair of Circular Economy at BTU. "Printed circuit boards in particular contain a large number of valuable metals that have so far often only been recovered at great chemical and energy expense."

Recovering metals from electronic waste

Biomining uses naturally occurring bacteria that are harmless to humans and the environment. These oxidise iron and sulphur compounds and, among other things, remove copper from the coating of the circuit boards. In addition to oxygen, the microorganisms only require small amounts of nutrients and CO₂ as a carbon source to grow.

"The particular advantage of our approach lies in the combination of recycling and CO_₂ utilisation," says Abendroth. "The microorganisms work at moderate temperatures, consume CO_₂, replace conventional chemicals and enable a reusable leaching solution. This significantly improves the environmental and CO₂ balance of the entire process."

New demonstration plant for the biological recycling of printed circuit boards

The process is being investigated and further developed by the BTU chairs of Circular Economy and Process and Plant Engineering. As part of the structural development project "BioMinCO2-Convers" (RIK Lausitz), a demonstration plant for the biological recycling of printed circuit boards is currently being built in Cottbus.

"With the demonstration plant, we are showing that biomining not only works in the laboratory, but is also scalable on an industrial scale," emphasises Abendroth. "This is a decisive step towards establishing biotechnological processes in the circular economy."

In addition to copper, the process also separates tin and zinc compounds as sludge. Precious metals such as gold and silver from the contact strips of the printed circuit boards can be separated and further processed separately. The biological process solution is regenerated and reused after each run.

Co-operation partner

The complete plant technology is being realised by Rhode+Wagner Anlagenbau GmbH from Ebersbach-Neugersdorf. Another industrial partner is Impala-Süd GmbH. Their Biotechnology specialists are investigating CO₂ uptake and conversion by the bacteria during the growth and leaching processes.

"For Lusatia, the project offers the opportunity to combine new industrial value creation with climate protection and resource efficiency," says Abendroth. "Biotechnological recycling can become a building block for structural change in the region."

While the laboratory work is still ongoing, the first components of the demonstration plant are already being assembled in Cottbus. The annex is to be transferred to quasi-continuous operation by the beginning of 2027.