Using banana peels to remove metals from polluted water: an aPEELING option

by Candace Rowell on March 19, 2012

Researchers have found banana peels can remove toxic metals from contaminated water just as well as many expensive laboratory methods. 

Access to Clean Water: A Basic Human Right 

A simple turn of the faucet delivers an endless supply of clean and refreshing H2O – in our homes, our offices, and even water used to flush our toilets. Clean drinking water is so readily available that we don’t have to think about where it is coming from or how we are going to get it. Access to clean drinking water is a basic human right that we enjoy on a daily basis. Unfortunately, this right isn’t the reality for millions of people around the world.

The World Health Organization [WHO] estimates that 884 million people world-wide do not have access to clean drinking water.  Over half of these individuals live in developing African countries where the consequences of drinking unclean water account for millions of deaths each year. Children, 5 years or younger, are the most vulnerable. In the past, drinking unclean water typically meant high risk to diarrheal diseases caused by bacteria or viruses. Today, drinking unclean water can mean much, much more.

With the ever ongoing and increasing industrial activities in developing nations across the globe, water quality in the most impoverished areas has become increasingly worse. Bacteria and parasites in the waterways of third world countries are no longer the only worries; issues of mining and heavy industry pollution are now adding to the clean water crisis- often times in the form of toxic heavy metals. Exposure to heavy metals [including: lead, mercury, copper, cadmium, chromium] can cause developmental defects in children, neurological effects such as memory loss and behavior changes, chronic diseases like cardiovascular disease, and it may lead to certain types of cancers.

Banana Peels: Removing the Metals

There have been numerous technologies developed to specifically remove metal toxicants from polluted waters- silica, alumina, activated carbon, and resins have all been proven successful… and expensive.  While they perform in the high tech laboratories of developed countries, mass manufacturing and distribution of these products in developing nations are expensive and impractical. For rural and remote villages, activated carbon filters are just not a sustainable option for water purification. But, banana peels are.

Using water from Brazil’s Paranhas River and locally grown bananas, researchers at Sao Paublo State University have demonstrated that dried banana peels can successfully remove copper and lead [two common metal pollutants] from contaminated water.

Banana peels contain nitrogen, sulfur, and carboxylic acids; the acids are responsible for the peels’ ability to bind the toxic metals and remove them from the water. Because of the high number of these acids in the peels, not only can banana peels remove the contaminants, but they can do it just as well, and in some cases better, than more expensive technological options.  And it’s easy. Without any technical preparation, dried banana peels successfully remove metals.

In areas in South America and sub-Saharan Africa where bananas are a common resource and contaminated water is a common problem, banana peels offer a sustainable and practical way to remove toxic metals from drinking water. By using the same banana peels up to 11 times without replacement, families can successfully minimize their risk of exposure.

Banana peels don’t kill parasites or bacteria, and they aren’t going to protect children from viruses. But, banana peels may offer millions of families around the world the opportunity to drink water free of heavy metals. A basic solution to promote a basic right.

 Image: By darwin Bell from San Francisco, USA (Oh just peel it already!  Uploaded by Fæ) [CC-BY-2.0 (www.creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
Seema Jolly March 19, 2012 at 2:39 pm

Candace, do you know how the peel actual works as a filter (when I think of a banana peel, it doesn’t seem very porous, so I’m wondering how the water passes through the peel… or is the peel mashed up in the filter)? Does the water end up tasting like banana (perhaps this last question you can’t answer :))? There are a lot of other issues with banana production, but people aren’t going to stop eating them anytime soon, so it’s interesting to hear about an innovative way to use the plant. (sidenote, when I spent some time in India, I thought it was really interesting that they would use banana leaves to make “disposable” plates and bowls — literally dried leaves threaded together with some sticks and it was a great use of a local resource without creating more trash that won’t decompose.)

Thanks for writing this!

Candace Rowell March 19, 2012 at 2:54 pm

Hey Seema – The banana peel was actually dried and minced and used like a “stationary phase” in a column. Meaning the water was basically allowed to flow over the banana peel (which was well minced to maximize exposed surface area). Use of the banana peeling in a home would take some creativity in development and design as far as technique. About the banana taste – it wasn’t addressed in the research but would definitely have to be considered. It’s been shown in previous studies that taste and appearance of water greatly affect whether people use certain cleaning/filtering (like boiling water or using biosand filtration) techniques in their homes.
I can relate to your sidenote – no part of the banana was wasted in Tanzania. Everything has a use!

Angela March 19, 2012 at 7:11 pm

Also wondered about the filtering technique and taste so thanks for clarifying. Does the ripeness of the banana/banana skin actually affect the filtering – and, do different banana types filter differently? (e.g. plantains, which are used both ‘green’ and ripe)

Candace Rowell March 20, 2012 at 5:08 pm

Hi Angela,
Really good questions. I unfortunately have no answers for them. Neither the type or the ripeness of banana peels used were noted in the study.

Jennifer March 20, 2012 at 1:19 pm

Did the peels have no effect on the other metals besides copper & lead? I

Candace Rowell March 20, 2012 at 4:59 pm

Hi Jennifer – The study focused on copper and lead removal because these were the pollutants of concern in the Paranhas River [where they took their water samples from]. The researchers noted banana peels may be used for a variety of metal ions but more research is needed to determine how well this method works for each metal.

Gaythia Weis March 22, 2012 at 12:58 pm

I believe that in the phrase “Because of the high number of these acids in the peels, ” ; number should be changed to concentration. I also wonder if reuse of the material would be likely to raise problems with bacteriological contamination. (Much as I have tried to warn a friend who insists on keeping her Brita filter water jug placed in a kitchen window!)

mohammadreza February 22, 2013 at 9:01 am

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That… was great. you helped me a lot and I should thank you. please, if possible, share an address to the article that you extracted the subject from.

granger May 3, 2013 at 6:21 am

We are conducting research about this . I just want to ask if one of the benefit of removing heavy metals is to prevent humans , animals and plants to be damaged. For example, if the water from river which have heavy metals can contaminate soil. so if the soil is contaminated the roots will also be affected thus contaminating the plants. When humans eat the fruit from the plants, the food is also contaminated thus affecting human ?

granger May 3, 2013 at 6:22 am

We are conducting research about this . I just want to ask if one of the benefit of removing heavy metals is to prevent humans , animals and plants to be damaged. For example, if the water from river which have heavy metals can contaminate soil. so if the soil is contaminated the roots will also be affected thus contaminating the plants. When humans eat the fruit from the plants, the food is also contaminated thus affecting human ?
..

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vanshika June 2, 2013 at 1:12 pm

well we are doing research on this……..infact we are trying to make water purifier that could be used for domestic as well as for commercial purpose……….if possible………so i request you to suggest me some techniques for the same……..[in detail]………….

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