MIT scientists find that brewer's yeast absorbs heavy metal Metal Tech News – June 15, 2022
While drinking an ice-cold pint of beer may not flush lead from your system – there is not a libation strong enough for that task – the yeast used to brew your favorite ale may prevent the heavy metal from getting into your body in the first place. And like they say, "16 ounces of prevention is better than a pound of cure" – or something like that.
Researchers at the esteemed Massachusetts Institute of Technology's Center for Bits and Atoms have discovered that the inactive yeast often discarded after the brewing process can efficiently and economically scrub even the minutest traces of lead from drinking water.
The method is so efficient that the team of MIT scientists calculate that the yeast discarded from a single brewery in Boston would be enough to treat the city's entire water supply. This discovery offers a win-win – removing heavy metal from the water and repurposing the waste product.
Lead and other heavy metals pose a serious health risk. Unlike organic pollutants, most of which can be eventually broken down, heavy metals don't biodegrade and persist indefinitely in water and the body.
Even in the tiniest concentrations, lead is highly toxic, especially affecting children as they grow. The European Union has reduced its standard for allowable lead in drinking water from 10 parts per billion to 5 ppb. In the U.S., the Environmental Protection Agency has declared that no level at all in water supplies is safe.
On top of the natural processes that leach lead into water supplies, mining and electronic waste have contributed to higher lead counts in water.
MIT says average levels in bodies of surface water globally are 10 times higher than they were 50 years ago, ranging from 10 ppb in Europe to more than 100 ppb in South America.
"We don't just need to minimize the existence of lead; we need to eliminate it in drinking water," says MIT Research Scientist Patritsia Statathou. "And the fact is that the conventional treatment processes are not doing this effectively when the initial concentrations they have to remove are low, in the parts-per-billion scale and below. They either fail to completely remove these trace amounts, or in order to do so they consume a lot of energy and they produce toxic byproducts."
The MIT discovery overcomes these challenges with a process that efficiently removes even the tiniest lead concentrations.
"Our study demonstrates that the process can indeed work efficiently at the much lower concentrations of typical real-world water supplies, and investigates in detail the mechanisms involved in the process," said Brown University postdoc and MIT Visiting Scholar Christos Athanasiou.
The team found that a type of yeast widely used in brewing and in industrial processes, called S. cerevisiae, was highly effective at removing lead from water. A single gram of the inactive, dried yeast cells was capable of removing up to 12 milligrams of lead from solutions with initial lead concentrations below 1 part per million. They also showed that the process takes less than five minutes to complete.
Because the yeast cells used in the process are inactive, they require no particular care, which sets this discovery apart from other processes that depend on living biomass that need nutrients and sunlight to keep the materials active.
The concept of using biosorption, a process in which inert biological material is used to remove heavy metals from water, is not new to science. Being able to quickly and easily remove lead from water using an abundant product that is discarded after brewing up a cold ale is new.
Stathatou has estimated that to clean a water supply for a city the size of Boston, which uses about 200 million gallons a day, would require about 20 tons of yeast per day, or about 7,000 tons per year. By comparison, the Boston Beer Company, brewer of Samuel Adams Boston Lager, generates 20,000 tons a year of surplus yeast that is no longer useful for fermentation.
Devising a practical system for processing the water is the next stage of research for the MIT team.
"To scale up the process and actually put it in place, you need to embed these cells in a kind of filter, and this is the work that's currently ongoing," said Stathatou.
They are also looking at ways of recovering the yeast and lead.
"We need to conduct further experiments, but there is the option to get both back," she added.
The yeast left over at breweries across the nation could potentially be used to remove other heavy metals, such as cadmium and copper, from water, but further research is needed.
"This research revealed a very promising, inexpensive, and environmentally friendly solution for lead removal," says Sivan Zamir, vice president of Xylem Innovation Labs, a water technology research firm that was not associated with this research. "It also deepened our understanding of the biosorption process, paving the way for the development of materials tailored to removal of other heavy metals."
So, while enjoying a frosty mug of your favorite beer, know that you could be playing your part in removing heavy metals from drinking water. Listening to heavy metal while doing so is optional.
The findings are detailed in a paper titled "Lead removal at trace concentrations from water by inactive yeast cells" in the journal Nature Communications Earth and Environment. MIT Research Scientist Patritsia Statathou; Brown University postdoc and MIT Visiting Scholar Christos Athanasiou; MIT Professor Neil Gershenfeld, the director of CBA; and nine others at MIT, Brown, Wellesley College, Nanyang Technological University, and the National Technical University of Athens are authors of the paper.