The skin of a banana has been used to great comic effects in numerous slapstick routines for many years. It's also good for the skin and is a traditional cure for warts. You can polish shoes and silver with it. You can make wine with it and it's even been known to find itself being dried, wrapped in paper and smoked. Now, research published in the journal of the American Chemical Society claims that mashed up peel can remove heavy metals from river water.
Heavy metals can end up in the waterways of the world as a result of industrial or agricultural processes and have been linked to a variety of health problems, ranging from nausea and vomiting to lung, kidney and brain damage. While there are numerous purification methods are already employed to try and keep the nasties at bay, many involve significant cost and can carry their own toxic risks.
Adding to other work which has shown the benefits of using coconut fibers and peanut shells, Gustavo Castro and colleagues from Brazil's Instituto de Biociências de Botucatu at the Universidade Estadual Paulista have found that minced banana peel could quickly remove lead and copper from river water and is at least as effective, and in some cases even better than, existing methods.
The team found that the banana skin water treatment apparatus can be used up to 11 times without losing its cleansing properties. The use of banana skins is seen as very attractive for water purification because of low cost and the fact that no chemical modification is necessary for the process to work.
On the face of it, this seems to be a very promising use for an otherwise discarded waste product. Unfortunately, the university didn't get back to us when we inquired about what happens to the minced banana skin at the end of the process.
More detailed information is available in the research paper entitled Banana Peel Applied to the Solid Phase Extraction of Copper and Lead from River Water: Preconcentration of Metal Ions with a Fruit Waste, which has been published in the American Chemical Society's journal Industrial & Engineering Chemistry Research.