Biomining: Extraction and Recovery of Metals Using Biological Processes

Challenge: Complete recycling of metallic raw materials from electronic waste and waste streams

Millions of tons of electronic waste are generated worldwide every year. Smartphones, laptops, televisions—everything that flashes and beeps eventually ends up in the trash. Yet these devices contain valuable raw materials that are essential for our technological future. So far, however, only a fraction of them are recycled. The rest is incinerated or landfilled—sometimes with serious consequences for the environment and health. At the same time, demand is rising for metals such as rare earths and metals from the palladium group, 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. Not least due to disrupted supply chains, industry in Europe has already experienced the effects that precious metal shortages can have.

Microorganisms and microalgae as “metal dissolvers” and “metal eaters”

The term biomining describes processes based on the ability of microorganisms and microalgae to dissolve metals from solid materials through metabolic properties, often oxidative metabolic processes, while simultaneously binding or absorbing them on their cell surface. This research approach has the potential to significantly expand the possibilities of metal recycling, and possibly even change it fundamentally, as it may mean that highly concentrated acids will no longer be needed for leaching in the future. Thanks to microbial production, these acids are only present in low concentrations. At the same time, biological processes are more environmentally friendly and energy-efficient than previous chemical processes, as process parameters can often be implemented with little effort. 

Thanks to our wide-ranging expertise with various organisms (microorganisms, microalgae), we have already investigated various approaches to extracting or recovering metallic raw materials from waste streams, spoil heaps, or electronic scrap.

This involved both the release of metal ions through biological leaching (bioleaching) and the recovery of dissolved metals through biological processes such as biosorption (adsorption to microorganisms or biological materials), bioaccumulation (uptake and storage of metals in cells) or bioprecipitation (precipitation of metals through the activity of microorganisms).

Example: Extraction of rare earths from electronic waste using biomining

Microorganisms such as Pseudomonas aeruginosa or chromobacteria were applied to shredded electronic waste. They produce acids or other substances that dissolve metals such as palladium or neodymium from the material. This process is called bioleaching. The dissolved metals are then found in a liquid from which they can be filtered out again by microalgae such as Galdieria sp. These algae act like biological magnets that bind the metal ions to their cell surface—a process known as biosorption. We investigated this in the RüBioM feasibility study.

Immobilized or suspended biomass

For effective process control, we use immobilized or suspended biomass, for example in a fixed-bed circulation reactor. In this way, heavy metals can be separated from cooling lubricants. A fixed-bed circulation reactor can also be designed to use scrap metal as a carrier material.

Focus of further research projects

The foundations have been laid—and the direction is promising. In order to design biomining processes that also work on an industrial scale, they must be further optimized, scaled, and evaluated in terms of their economic viability. This also involves identifying the most suitable microorganisms, improving their cultivation conditions, and at the same time scaling functioning processes on a small scale for industrial applications.

Advantages of biomining processes

Mild process conditions: environmentally friendly and potentially cost-effective

An advantage of all biological mining processes is that they take place under mild conditions and at low temperatures. No toxic chemicals need to be added; instead, the organisms used are able to mobilize specific metals in a targeted manner. This makes biomining not only environmentally friendly, but also selective and potentially cost-effective.

Recovery strengthens resilience and reduces dependence on imports

The social relevance of this research can hardly be overestimated. 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.

Furthermore, biomining processes open 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. At the same time, biomining offers the opportunity to supplement or improve existing recycling processes, for example through the targeted recovery of metals that are difficult to extract using conventional methods.