Gallium is a strategically important element and the backbone of the semiconductor industry for mobile data transmission and optoelectronics applications. It is used in wafers (GaAs, GaN), electronic chips, and optical components such as LEDs and lasers. One kilogram of gallium currently costs around €1,000, and the price is rising. During industrial processing, a considerable amount of the raw material is already lost when etching or polishing processes remove material. The residues are sometimes highly diluted or the mixture is chemically complex, making recovery by conventional chemical means difficult. This is where the research of the Helmholtz Institute Freiberg for Resource Technology (HIF) of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) comes in. Using a biotechnological process, the wastewater from Freiberger Compound Materials is treated in a pilot scale facility and the gallium is recovered.
Gallium is considered a critical raw material that is essential for both the development of renewable energy sources and the development of energy-efficient systems. Efficient recycling technologies are needed to ensure the availability of gallium for high-tech applications in the future. The biotechnology department at HIF transfers biochemical principles and biological functional carriers to completely new applications, thereby linking the biotechnology with resource technology. Metals are recycled using biosorption, in which biomolecules with the ability to bind to specific ions or molecules are the key reagents. Siderophores have proven to be suitable for recovering gallium from industrial wastewater. Siderophores – Greek for “iron carriers” – are a group of around 500 low-molecular compounds that are characterized by the formation of stable complexes with iron ions. In nature, they are produced by numerous bacteria, fungi, and plant roots in order to absorb iron from the environment.