Water contamination presents a huge challenge globally. In addition to the millions of people who die each year from water-related diseases, all life forms are at risk as heavy metals (e.g., mercury) found in water tend to accumulate in fish, plants, etc. Various chemical systems which attempt to deal with this problem are expensive and often require use of materials that are themselves toxic. Natural alternatives (e.g., sawdust, peanut shells, sugar cane) have been employed with mixed results. But now researchers may have discovered a cheap, effective solution that can work even better than the chemical stuff: banana peels!

Brazilian scientists from the Universidade Federal de Sao Carlos mixed dried, pulverized banana peels with contaminated water, and measured how well they did at extracting heavy metals compared to other conventional methods. The banana peels were 200-300% more effective at absorbing copper than peanut husks, sawdust, bentonite (a clay) or perlite (volcanic glass). For lead absorption, the banana peels were 312% better than perlite, 89% better than sawdust and 42% better than peanut husks. The banana peel was so effective at absorbing these metals that it could be reused 11 times without degradation. Repeating the process allows the water to be purified completely, the researchers claim.

Given the roughly 100 million tons of bananas grown annually around the world, there’s an enormous supply of banana peels that are going to waste…when they could be going to treat waste.  While banana peels were once regarded as little more than the punch line of a clichéd joke, they’re now being investigated for previously unimagined benefits. For example, researchers are exploring the potential of banana lectin called BanLec to provide natural, topical protection against HIV.

Bonus: Natives of the Brazilian Amazon eat fish up to 700 times a year — yet those who regularly ate tropical fruit, including bananas, had 80% less mercury buildup in their system in one study. Researchers speculate that something in the fruit – nutrients, enzymes or fiber — acts dramatically to block mercury absorption.

Published May 1, 2011