Downing a pint of beer may not flush lead from the imbiber’s system, but the yeast used to brew the beverage may prevent the heavy metal from getting into the human body in the first place. Researchers report that inactive yeast discarded after the brewing process could be effective as an inexpensive, abundant material for removing lead contamination from drinking water supplies.

The biosorption process studied by researchers from the National Technical University of Athens, MIT, Wellesley College and Brown University proved effective at removing lead from water sources down to part-per-billion levels of contamination. The treatment was demonstrated with S. cerevisiae, a type of yeast widely used in brewing and in industrial processes, on pure water spiked with trace amounts of lead. A single gram of the inactive, dried yeast cells was observed to remove up to 12 mg of lead in aqueous solutions with initial lead concentrations below 1 part per million. The process described in Nature Communications Earth and Environment was shown to be rapid, requiring less than five minutes to complete.

Schematic depicting the addition of freeze-dried yeast cells in lead-containing aqueous solutions, adsorption of lead ions and separation of biomass and supernatant after the required contact time via centrifugation for further analyses. Source: Stathatou, P.M., Athanasiou, C.E., Tsezos, M. et al. Commun Earth Environ 3, 132 (2022)

Waste yeast discarded from a single brewery in Boston was calculated to be sufficient 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.

The researchers plan to develop and scale up a practical system for processing the water and retrieving the yeast, which could then be separated from the lead for reuse.