A team of scientists at the University of Natural Resources and Life Sciences (UNRLS) in Austria propose using spent brewer’s yeast — a byproduct of beer brewing — to recycle and separate metallic waste.

Because electronic waste (E-waste) in notoriously difficult to recycle due in part to the number of different metals used in product manufacture, the researchers sought a way to selectively separate the metals for reuse.

Source: Pixabay

To accomplish this, the researchers separated biomass from leftover brewing residue and dried the biomass before using it in the selective separation process.

The researchers explained that making the biomass appropriate for this is adsorption, wherein electrostatic interactions on the surface of the yeast attract metal ions, causing them to stick to the surface. The researchers suggest that altering the pH of the solution enables the yeast to attract more metal ions or different metal ions.

In the lab, the scientists tested the biomass on metals including zinc, aluminum, copper and nickel, testing each metal solution using assorted pH and temperatures to gauge the strength of the interactions and to determine how even more metal could be recovered.

During those tests, the researchers reportedly recovered 50% aluminum, 40% copper and more than 70% zinc using the spent yeast. Further, the biomass was tested on a polymetallic waste stream, with more than 50% copper and more than 90% zinc successfully recovered. The scientists also determined that the yeast itself can also be recycled following metal recovery.

The findings are detailed in the journal Frontiers in Bioengineering and Biotechnology.