RüBioM − Feasibility Study on Metal Recovery Using Biomining

Challenges

Millions of tons of electronic waste are generated worldwide every year from discarded smartphones, laptops, and televisions. These devices contain valuable raw materials, including rare earth metals. Currently, only a fraction of electronic waste is recycled, with the rest being incinerated or landfilled—sometimes with serious consequences for the environment and human health. At the same time, demand is rising for metals such as palladium and neodymium, which are indispensable for the manufacture of electronics, electric motors, and wind turbines. However, the supply of these metals is often uncertain, as they are only mined in a few countries and are subject to geopolitical risks.

Objectives and project plan

The aim of the RüBioM feasibility study was to investigate biological processes such as bioleaching and biosorption for recycling metals from electronic waste. So-called bioleaching processes are used to release metals. Various microorganisms produce acids that can be used to dissolve metals such as palladium or neodymium from the material. Biosorption processes are used to recover the dissolved metal ions: specific microalgae are able to absorb them, acting like a biological sponge or filter.

As part of the RüBioM project, various microorganisms and algae were tested to find out those that are particularly well suited for metal recycling. The results show that palladium in particular can be effectively mobilized using biological processes. In laboratory tests, a release rate of over 13 percent was achieved using special bacteria – significantly more than with the chemical methods considered in the project. Algae showed a high absorption capacity: they were able to remove over 30 percent of the dissolved palladium from the solution.

Neodymium, on the other hand, was more difficult to recover biologically. Chemical processes performed even better here, but initial biological approaches also showed potential.

Scaling up in a fixed-bed circulation reactor

The process was tested on a larger scale in a fixed-bed circulation reactor (FBUR), in which the fixed bed of particles with immobilized biomass is periodically circulated. Here, too, palladium was successfully mobilized, albeit with challenges such as biofilm formation and uneven flow. Nevertheless, the experiment shows that biomining not only works in the laboratory, but can also be further developed for industrial application.

Impact: Bio-based metal recycling is sustainable and reduces dependence on imports

In a world that is increasingly dependent on digital technologies, the demand for rare and valuable metals is constantly growing. At the same time, awareness of sustainability and resource conservation is also growing. Biomining offers a solution that combines both aspects: it enables the recovery of critical raw materials from waste streams, reduces dependence on imports, and protects the environment.

It also opens up new perspectives for the circular economy, in which products are no longer simply disposed of but are viewed as a source of raw materials. Biomining processes offer the opportunity to supplement or improve existing recycling processes, for example through the targeted recovery of metals that are difficult to extract using conventional chemical processes.

Outlook

For technical application, the processes must be further optimized, scaled up, and evaluated economically. The aim is to identify the best microorganisms, improve their cultivation conditions, and design the processes so that they also work on an industrial scale.