Inexpensive Arsenic Filtration System Uses Cattails, Aquatic Weeds

Published on July 15th, 2009 | by

An environmental and civil engineer has developed an inexpensive arsenic filtration system that uses aquatic plants, namely cattails, to remove poisonous arsenic from drinking water, which could improve the health of millions in countries around the world whose local water supplies are naturally contaminated with the toxic substance. An estimated 57 million people are drinking groundwater with arsenic concentrations measured above the World Health Organization‘s standard of 10 parts per billion.

Image: clairityCattails
Cattails

Jeremiah D. Jackson, Ph.D., P.E., of San Diego, CA, says he started his research after his brother, a journalist, mentioned the dire need for filtering the arsenic from groundwater in countries such as India, Pakistan, Mexico, and even parts of rural U.S. Arsenic-contaminated water is responsible for epidemics of arsenicosis (chronic arsenic poisoning from drinking water) in Bangladesh, and a cheap effective filtration system could save millions of lives each year.

Jackson set up an experiment on his patio, with cattails planted in sand in five-gallon buckets filled with water. Some were left untreated, and others were dosed with various concentrations of arsenic. After measuring the arsenic removed by the cattails, he felt justified in building a prototype in a wading pool, with the guiding principles of no moving parts, low cost to build, and to be easily constructed by a layperson.

He ran the experiment for about six weeks, and found that it resulted in an 89% removal of arsenic to about 37 micrograms per liter, a level below the world health standard of 50 micrograms per liter.

“The cattail actually thinks the arsenic is a nutrient. It absorbs it as if were a nutrient, a fertilizer. And I found the plants actually flourished.”

By his calculations, a system like his would cost a family about 21 cents per 1,000 gallons of treated water (compared to more complex technologies costing from $50 to $300 per 1,000 gallons). He believes the cattails can absorb the arsenic for up to 50 years, but suggests they just decommission the device every ten years.

Jackson’s research was published in the April 2007 issue of Civil Engineering Magazine in a special section, the Arsenic Crisis.

[Via]


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10 comments

  • This is a really interesting piece of info.
    I’ve traveled in places like India and they use everything they can for food or fuel…so you’d have to prevent people from burning the plants for cooking fuel (thereby releasing the arsenic back into the environment) or feeding it to cattle (arsenic ends up in milk, meat & poop which also gets burnt for fuel.)

  • Cattails and other aquatic weeds collect many kinds of toxins besides arsenic. If they did not, harvesting of the cattails growing wild would be sufficient to completely end the world’s food shortages. Uncontaminated, this is a terrific food plant. And most of it is uncontaminated, but mapping out what is fit for human consumption has not been begun, much less done.

    That which has been ‘naturally’ contaminated has proven stable. It appears safe to leave those swamps where the cattail has cleaned up after us alone. The toxins stay there. There are many such places in the streams of Africa and Asia. Let sleeping toxins lie.

    Uncontaminated, this is also one of the most versatile fuel plants. Charcoal, ethanol and fuel gas can all be readily made. Moderately contaminated, we can get ethanol or fuel gas, but will also have a contaminated sludge to dispose of.

    The other aspect of this plant and the other aquatic weeds is that they are a driving force in worldwide desertification. These are dessication machines and siltation machines destroying the world’s waterways and sucking the land dry. Their reduction and control is key to solving the world’s problems. Their resilience makes their control a never ending effort. It can only be supported by their harvest for fuel and food. And there, their useful ability to collect toxins is only an obstacle.

  • Anytime we can find a nature remedy for what ails the planet we’re much better off. Hopefully this is a solution that can be adopted on a very wide scale, assuming they don’t pose a threat to waterways as mentioned above.

  • The World Health Organization’s acceptable level of arsenic in drinking water is 10 micrograms per liter not 50, and there has been some talk about that being too high.
    http://www.who.int/ipcs/features/10chemicals_en.pdf

    With that being said, cleaning water through the method discussed above along with the use of a filter is much more sustainable than our current method (using less energy and creating less waste) and it can produce water that is just as clean (and in some cases cleaner) than tap water in the US.

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