Engineer’s simple discovery could save lives
Find: Cattails filter arsenic from water for drinking
A recent discovery by a Del Mar civil engineer may bring developing countries closer to eliminating arsenic-contaminated drinking water and the associated health problems afflicting impoverished communities.
Jeremiah Jackson, Ph.D., is a senior principal engineer who works for San Diego-based Kleinfelder.
A phone conversation in 2002 with his journalist younger brother about arsenic contamination in India planted the seed for the idea.
“That night as I was lying in bed, I remembered that while doing work, I learned about certain aquatic plants that remove some metals from water,” Jackson said. “And, because arsenic has a lot of the characteristics of metals, I thought maybe these plants could be used to filter drinking water.”
Jackson said he wanted to create a system that was simple, inexpensive and didn’t take an expert to set up. But, busy with other projects, it took a few years before he got back to the idea, and in that time, his brother passed away.
“I finally had some free time I could devote to really thinking about how the process could work,” he said. “And I thought it would be a good way to honor my brother. After all, he was the one who brought the issue to my attention.”
After some small-scale experimenting Jackson built a full-scale prototype filtration system in the backyard of his Del Mar home.
He dug a 12-square-foot hole, large enough to treat enough water to support a family of five, and lined it with plastic. He added sand and planted common cattails at 1-foot intervals. He then used buckets to add water to the pond.
At either side of the pond, he placed a milk jug with the top cut off, holes punched in the sides, and put rocks in the bottom to keep them in place.
For six weeks, he added a bucket of water and removed a bucket of water every day.
The contaminated water went in the same jug every day, and the filtered water was removed from the opposite jug using a hand pump.
On average, the cattails removed 89 percent of the arsenic, with a concentration of 34 micrograms per liter, a level the World Health Organization considers acceptable for long-term human consumption.
The estimated annual cost to treat 1,000 gallons is 21 cents, and the greatest expense used in Jackson’s prototype was the small $3 hand pump.
He ran the six-week process once in the winter and once in the summer to see if the outcome would change due to the weather. He said because of the temperate climate in Del Mar, the results were basically the same.
“The uptake mechanism is the plant itself,” Jackson explained. “The arsenic behaves as if it’s phosphorus, a nutrient.”
That’s why it won’t work year-round in a really cold climate, where the cattail would likely go dormant during the winter.
“It works in a temperate or tropical climate,” the conditions in most of the areas where contaminated water is a problem, he explained.
The idea was well received when Jackson presented it at a conference about arsenic in drinking water two years ago in New Delhi.
Since then, representatives from the Indian Institute of Technology have contacted him about large-scale water filtration for rice patty irrigation. He said the solution is simple: plant cattails in the irrigation canals.
He also had an essay published in the American Society of Civil Engineers Journal.
Jackson recently learned that he was nominated for a World Technology Summit Award in the health and medicine category, joining the likes of Harvard, MIT, Calgary and Cambridge professors.
“It’s a pretty impressive group,” Jackson said. But he mainly hopes the nomination will further spread the information to the corners of the world where it is most needed.
For more information, visit www.wtn.net or kweb.kleinfelder.com.
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