Joint research between BOKU Tulln and the IMC Krems University of Applied Sciences shows great potential in the recovery of valuable materials from electronic waste. In the laboratory, a recovery of up to 85% of rare earths was achieved.
Development of the Bioextraction and Bioaccumulation Process
The collaboration between BOKU Tulln and IMC Krems University of Applied Sciences has enabled the development of an environmentally friendly and sustainable two-stage process to recover rare earths by improving bioextraction and bioaccumulation. In the bioaccumulation stage, metal recovery rates of up to 85% were achieved from electronic waste.
The key to success lies in the combination of biotechnological processes. The promising bases for these methods, currently in development, were recently published in the renowned journal Frontiers in Microbiology.
Context and need
The sharp increase in demand for electronic devices in recent years, used in a wide range of devices such as mobile phones, electric vehicles and computers, has increased the amount of waste containing rare earths. Most of this waste still ends up in landfills unused, even though rare earths are an important source of raw materials and have been classified as critical raw materials by the European Union.
For this reason, intensive research is being carried out to find efficient recovery methods. Compared to other methods, microbiology-based methods such as bioextraction and bioaccumulation represent a promising “green” technological alternative to recover critical raw materials from e-waste. They are cost-effective, do not produce hazardous or polluting secondary waste and consume less energy.
Process Fundamentals
The basic principles of the processes are based on the production of acids by certain microorganisms that can “leach” metals such as iron, copper or aluminum from electronic waste. These metals interfere with the absorption process of valuable rare earths in subsequent bioaccumulation. Both methods have been investigated for some time by the two partners, BOKU Tulln and the IMC Krems University of Applied Sciences, and the research teams have now joined forces in a promising collaboration and combined their expertise.
“Nothing Comes from Nothing”: Training for Microbes
In addition to the researchers, other key actors in the bioextraction process, summarized in the joint technology, participated in the current study: bacteria of different species. For example, they used Acidithiobacillus thiooxidans and Alicyclobacillus disulfidooxidanswhich were originally collected from an acidic (pH 2.6) mining lake in the Czech Republic and then grown together in the laboratory.
These acidophilic and chemolithotrophic organisms thrive in acidic environments and obtain their energy from the oxidation of inorganic compounds. In terms of bioaccumulation, Escherichia colithe well-known intestinal bacteria, proved to be the most successful accumulator of rare earths.
Practical Challenges and Innovative Solutions
The main practical challenge for the enrichment process used to recover rare earths is the high content of other metals typically found in electronic waste. In particular, iron, copper and aluminum interfere with the biotechnological process. To overcome this problem, the researchers came up with another innovative option: “training” the microbes. Using a device called a morbidostat developed at IST-Klosterneuburg, organisms gradually become accustomed to higher concentrations of metals. However, the bioaccumulation process must be carried out carefully so that organisms do not lose their ability to accumulate valuable substances.
Efficiency in Stages
The methods currently used to extract rare earths are based on chemical processes, which are associated with the formation of environmentally harmful byproducts and the creation of new problematic substances. A combination of biotechnological methods has clear advantages over chemical methods, since both leaching and accumulation in bacteria cells are environmentally friendly and sustainable, and no hazardous substances or pollutants are produced at any stage of the process. However, more research is needed to overcome the wide variation in the composition of e-waste. Even if the concentration of interfering metals such as aluminum, iron or copper changes, the technology must work in such a way that the results are reproducible and reliable. Researchers from BOKU and IMC Krems are pursuing several strategies to achieve this. Another strategy is to acclimate the bacteria responsible for bioextraction and bioaccumulation to high concentrations of interfering metals. This is possible using a system called a morbidostat. In this system, microorganisms are exposed to a gradually increasing concentration of interfering metals and then wait until acculturation occurs and the organisms begin to grow.
Complementary Systems and Future Research
Along with the conditioning of microorganisms, systems are being tested that can trigger a reduction in the concentration of interfering metals. The materials investigated include so-called lignin hydrogels developed at BOKU. The combination of these strategies aims to ensure the efficiency and sustainability of the innovative combination of bioextraction and bioaccumulation to develop a new ecological method for recycling scarce rare earth elements.
Joint research between BOKU Tulln and IMC Krems University of Applied Sciences has demonstrated great potential in the recovery of rare earths from electronic waste using advanced biotechnological processes. With a recovery rate of up to 85% and the absence of hazardous waste, this approach is presented as a sustainable and effective alternative to traditional chemical methods.
BMI Krems
Located in the heart of the province of Lower Austria, IMC Krems is committed to promoting internationalization, practical education and innovation. With more than 160 partner universities, more than 1,000 partner companies worldwide and more than 3,000 students from 90 countries at two locations in Austria, IMC Krems offers 27 full- and part-time bachelor’s and master’s programs and four continuing education courses. in their core subjects of business, digitalization and engineering, health sciences and life sciences.
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