How to Clean Water With Old Coffee Grounds

Italian researchers have figured out how to turn spent coffee grounds into a foam that can remove heavy metals from water.

In Italy, coffee is practically a religion. Few other countries have made such a high art of turning the roasted beans into drinks both elaborate and deceptively simple—the bracingly bitter ristretto, the feather-light cappuccino, the booze-infused caffè corretto. As a result, at the end of the day, cafes from Milan to Palermo dump tons of spent coffee grounds in the trash along with the stale biscotti and unsold panini.

So it’s fitting that it’s a team of Italy-based researchers that has come up with an innovative way of reusing these spent coffee grounds. The team, at the Istituto Italiano di Tecnologia (IIT) in Genoa, is using coffee grounds to clean water, turning the grounds into a foam that can remove heavy metals like mercury.

“We actually take a waste and give it a second life,” says materials scientist Despina Fragouli, who authored a new study about the coffee discovery in the journal ACS Sustainable Chemistry and Engineering.