Common cactus could be used to clean water

April 30, 2010 by Lin Edwards, report
Photo of Opuntia littoralis var. vaseyi at the Regional Parks Botanic Garden, Berkeley, California. Image credit: Wikipedia.

( -- Access to clean drinking water is lacking in many parts of the world but most technologies to clean water to make it fit for drinking are expensive and hard to maintain. Now researchers propose a cactus common around the world could be used to provide a cheap and easy solution.

The prickly pear (Opuntia ficus-indica) uses mucilage (a gum) to store internally, and scientists from the University of South Florida in Tampa, led by Dr Norma A. Alcantar, have tested the cactus on water to which they added high levels of and bacteria (Bacillus cereus). They found when the gum is extracted and mixed with dirty water it acts as a flocculant, causing the bacteria and sediments to settle at the bottom of the container, removing 98 percent of the contaminants. They say that boiling a slice of cactus and then adding it to unclean water would provide the cheapest and simplest means of cleaning water in places where other technologies are unavailable or unaffordable.

More research is needed to identify exactly what are removed, and to provide a means for the users to be sure all bacteria and viruses have been removed. It may also not be a feasible solution for in areas where the prickly pear does not grow, and since it is highly invasive it may not be wise to introduce it if the plant is not already present in an environment.

Alcantar said their next step was to test the cactus on natural supplies of water, but she said the prevalence of the cactus made it an extremely affordable way of purifying water, and the practice would also find cultural acceptance.

The method of using the cactus to purify water was traditional in rural Mexico in the 19th century, but until now no scientific evidence of its effectiveness had been obtained. The cactus is already farmed in Mexico and parts of the US for the pads, which are used as food for livestock and people, and the edible fruits, called “tuna” or “cactus figs”. The sap is also used as a first aid treatment, similar to aloe vera, and the pads can be used for making fibers for baskets and even paper. The prickly pear is native to the US, Mexico and South America, but is now widespread in the Mediterranean and in Africa and Australia, where it has become an invasive weed.

Explore further: Arizona cactus is threatened

More information: Removal of Sediment and Bacteria from Water Using Green Chemistry, Environ. Sci. Technol., 2010, 44 (9), pp 3514-3519. DOI:10.1021/es9030744

Related Stories

Arizona cactus is threatened

July 11, 2006

More than 170 new homes are built in the Phoenix and Tucson areas each day and reportedly means many cactus species are being threatened.

How Did Cactuses Evolve

May 15, 2006

In a groundbreaking new study in the June issue of American Naturalist, Erika J. Edwards (Yale University and University of California, Santa Barbara) and Michael J. Donoghue (Yale University) explore how leafy, "normal" ...

Photosynthesis: a new source of electrical energy

February 18, 2010

French scientists have transformed the chemical energy generated by photosynthesis into electrical energy. They thus propose a new strategy to convert solar energy into electrical energy in an environmentally-friendly and ...

Recommended for you

New insight into Greenland's melting glaciers

July 17, 2018

New research into Greenland's glaciers will help bring accurate sea level rise forecasts – which are crucial in preparing for the impacts of climate change—a step closer.

Thawing permafrost microbiomes fuel climate change

July 16, 2018

A University of Queensland-led international study could lead to more accurate predictions or the rate of global warming from greenhouse gas emissions produced by thawing permafrost in the next 100 years.


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (2) Apr 30, 2010
"Access to clean drinking water is lacking in many parts of the world but most technologies to clean water to make it fit for drinking are expensive and hard to maintain."

Bleach, iodine and boiling are neither scarce nor expensive.
not rated yet Apr 30, 2010
"More research is needed to identify exactly what contaminants "

what? They did not bother to actually have a common water analysis lab test done on the water? And yet they published these "results".
5 / 5 (1) Apr 30, 2010
They certainly couldn't add every conceivable contaminant to a sample of lab water. They need to test further, on individual contaminants and multiple contaminants. (There's A LOT of them). This "common water analysis lab test" you refer to isn't quite that simple. Especially with all of the different bad thing that they could present into the water. You can use the test you bring up AFTER the process, but it doesn't quite work the way you're thinking.
2 / 5 (1) Apr 30, 2010
I am thankful that plants make water and air cleaner. Good thing scientists figured it out too.
not rated yet Apr 30, 2010
When I moved to the Sonoran Desert 18 years ago, I fell in love with Prickly Pears.
not rated yet Apr 30, 2010
When I moved to the Sonoran Desert 18 years ago, I fell in love with Prickly Pears.

You fell in love with a cactus? My fetish book doesn't list cactiophilia in it. Its quite possible that you have invented a new one!

Seriously tho, it never ceases to amaze me the number of problems offered by mother nature, and the corresponding plethora of solutions served up on the same plate.
5 / 5 (2) Apr 30, 2010

Bleach, iodine and boiling are neither scarce nor expensive.

you can drink the bleach and iodine if u want to shootist
4.5 / 5 (2) May 01, 2010
Bleach, iodine, and boiling. They kill the bacteria, but don't remove the nonliving contaminants.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.