The Challenge

Each year, millions of electronic devices like smartphones, computers, and televisions are discarded, contributing to what is known as "e-waste." According to the World Health Organization, e-waste represents the fastest growing waste stream globally. Alarmingly, the latest Global E-waste Monitor report indicates that e-waste is growing five times faster than the recycling rate. Between 2010 and 2022, the volume of e-waste surged by 82%, with projections indicating a further 32% increase by 2030.

When not disposed of or recycled properly, e-waste poses risks to both human health and the environment. The report revealed that only 22.3% of the e-waste generated in 2022 was effectively collected and recycled, which translates to $62 billion worth of recoverable natural resources going unaccounted for, exacerbating pollution risks.

The complex nature of e-waste makes it difficult to recycle, particularly due to the challenge of separating various metals. Although experts have proposed several methods for metal extraction, many solutions have limitations.

A Solution

Anna Sieber, a doctoral researcher at the University of Natural Resources and Life Sciences in Vienna, along with her colleagues, may have found a promising alternative: brewer's yeast, known scientifically as Saccharomyces cerevisiae. This single-celled fungus, also used in baking, is often discarded after brewing, making it both abundant and inexpensive.

Sieber explains that while extracting metals from solutions is the initial step, selectively recovering them remains challenging. However, utilizing spent brewer's yeast offers a cost-effective and environmentally friendly solution compared to traditional methods.

The Study

To explore this potential, the team collected 20 liters of inactive brewer’s yeast, which they subsequently froze, dried, and ground. They then introduced this yeast into solutions containing economically significant metals such as aluminum, nickel, zinc, and copper, as well as metals sourced from dismantled circuit boards. The yeast's surface engages in electrostatic interactions, allowing it to effectively absorb these metals.

By manipulating factors like temperature and acidity, the researchers were able to optimize the yeast’s metal absorption capabilities. They also tested the yeast’s efficiency against a polymetallic waste stream, soaking the yeast in acid baths to extract the collected metals.

The Results

The findings were impressive: they successfully recovered over 50% of aluminum, more than 40% of copper, and over 70% of zinc from the tested solutions. Zinc absorption improved by 7.6% with temperature adjustments, while aluminum recovery increased by 16% with pH modifications.

Sieber, the lead author of a publication in Frontiers, noted, "We demonstrated high metal recovery rates from a complex metal solution using an environmentally friendly and cheap biomass."

A Bonus Benefit

Interestingly, the research revealed that brewer's yeast could be reused multiple times without diminishing its effectiveness in binding metals—up to five times, in fact. Sieber remarked, "The metals can be removed from the yeast surface by acid treatment and thus could be recycled."

However, the researchers caution that further studies are necessary before this method can be implemented on an industrial scale. Postdoctoral researcher Klemens Kremser highlighted that the metal removal process was tailored for specific metals, which may not apply universally to different metal mixtures.

Despite these challenges, the potential is promising. Sieber pointed out that Austria produces a significant amount of beer, resulting in large quantities of wasted brewer's yeast. This method could help mitigate both yeast and electronic waste.

While many e-waste recyclers focus on more valuable metals like gold and silver, the metals tested in this study—aluminum, zinc, copper, and nickel—are still crucial in modern electronics, making this process valuable.

Biologist Kerry Bloom from the University of North Carolina noted that the abundance and low cost of yeast make this approach feasible for large-scale application, provided that e-waste recycling centers are willing to invest in new systems.

Perspective Shift

Following this research, scientists from MIT and Georgia Tech found another application for brewer's yeast. They created a water filter by encapsulating the yeast in hydrogel capsules, allowing it to capture lead while letting water flow freely. The yeast can be cleaned and reused, making it a biodegradable and eco-friendly solution for drinking water purification.

This research represents a multifaceted win: it addresses e-waste, enhances drinking water quality, upcycles discarded byproducts, and, of course, supports the continued enjoyment of brewing beer.

This article was originally published in the author’s free newsletter, Curious Adventure. It was edited and republished on Medium with her consent.

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