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upstart writes:

A new study shows that yeast, an abundant waste product from breweries, can filter out even trace amounts of lead:

Inactive yeast could be effective as an inexpensive, abundant, and simple material for removing lead contamination from drinking water supplies, according to a new analysis by scientists at MIT's Center for Bits and Atoms (CBA). The study shows that this approach can be efficient and economical, even down to part-per-billion levels of contamination. Serious damage to human health is known to occur even at these low levels.

The method is incredibly efficient. In fact, the research team has calculated that waste yeast discarded from a single brewery in Boston would enough to treat the city's entire water supply. Such a fully sustainable system would not only purify the water but also divert what would otherwise be a waste stream needing disposal.

[...] "We don't just need to minimize the existence of lead; we need to eliminate it in drinking water," says Stathatou. "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."

[...] Because the yeast cells used in the process are inactive and desiccated, they require no particular care, unlike other processes that rely on living biomass to perform such functions which require nutrients and sunlight to keep the materials active. What's more, yeast is abundantly available already, as a waste product from beer brewing and from various other fermentation-based industrial processes.

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, one single brewery, the Boston Beer Company, generates 20,000 tons a year of surplus yeast that is no longer useful for fermentation.

[...] Devising a practical system for processing the water and retrieving the yeast, which could then be separated from the lead for reuse, is the next stage of the team's research, they say.

"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," Stathatou says. They are also looking at ways of recovering both the cells and the lead. "We need to conduct further experiments, but there is the option to get both back," she says.

The same material can potentially be used to remove other heavy metals, such as cadmium and copper, but that will require further research to quantify the effective rates for those processes, the researchers say.

Journal Reference:
Patritsia M. Stathatou, Christos E. Athanasiou, Marios Tsezos, et al. Lead removal at trace concentrations from water by inactive yeast cells [open], Communications Earth & Environment, 2022. DOI: 10.1038/s43247-022-00463-0

Original Submission