Water contaminated with potentially toxic metals can be purified using banana peels as a filter, according to a study from the São Paulo State University (UNESP) in Botucatú, 230 kilometres from the city of São Paulo. “Current purification methods are costly and, paradoxically, use toxic substances,” Renata Castro, a food engineer and member of the research team, told Tierramérica.

“The low cost of banana peels makes them an excellent alternative. In addition, they do not need to be chemically altered in any way to capture heavy metals,” she explained.

Positive results were also obtained in tests using other natural materials, such as coconut fibre and peanut shells, but banana peels proved most effective.

The same banana peel can be used up to 11 times in a purification device without losing the ability to capture impurities. Banana peels can also be used to directly extract metals from river water.