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Students focus on affordable fluoride reduction process for African groundwater

Fluoride—an indispensable element for dental health, right? That’s why many cities in the United States add it to their drinking water. But what if you have too much?

Depending on where you are on Earth, you might have just that problem: too much fluoride. Due to the local rock chemistry, some regions’ groundwater naturally contains fluoride concentrations over 40 times the World Health Organization’s recommended upper limit for consumption. This can lead to health problems, including a painful condition known as skeletal fluorosis, where fluoride ions react with bones to change their chemical structure, weakening them and causing joint stiffness and, in extreme cases, skeletal deformity.

It’s an especially big problem in developing countries. “Although many de-fluoridation methods exist,” said Abigail Nypaver, a fourth-year chemical engineering student at Ohio State, “it has been difficult to have success in rural villages in developing countries. Factors like cost, cultural acceptability and availability of materials make developing solutions in these environments more difficult.”

Abigail and her classmates Aina Salahuddin, Kian Boon Low and Wen Dai are tackling this problem as part of their capstone effort in the Department of Chemical and Biomolecular Engineering. They are trying to design an effective but cheap fluoride treatment process for groundwater, starting with partner villages that other Global Water Institute efforts are working with in Tanzania.

In the capstone class, the students are considering the benefits and potential trade-offs of several methods of fluoride reduction—filtration, flocculation, and electrocoagulation.

Filtration is a technique that has potential, with a number of lower-cost options already in use with bone char, a type of activated carbon made from animal bones. Since cattle herding is an important industry in Tanzania, there is a ready supply of bones, and some furnaces already exist to produce this product. A major issue, however, is that filtration systems of this type—while highly effective—can be somewhat expensive. Other possible materials to be investigated include organic materials like soil and plant matter, which have been shown to be at least somewhat effective in removing fluoride.

Flocculation involves adding a chemical, alum, that makes the fluoride clump up visibly so it can be easily removed by simple filtration with cloth or mesh. One major hurdle that flocculation may face is cultural acceptance, as there may be an inherent mistrust of any “chemicals” being added to the village water supply, and villagers may refuse to drink water purified by flocculation.

Finally, electrocoagulation, where an electrode effectively “sucks” fluoride out of the water, may provide a possible alternative to traditional water purification methods. Although this method involves electricity—which is hardly standard in remote locations in developing countries—groundwater pumping systems that involve solar energy may have just enough extra current available to help clear fluoride out of the water.

Progress toward the solution

Abigail and her classmates work closely with Nathaniel Kramer, GWI Student Activities Program Coordinator. Nathaniel helps give the group context behind GWI’s work in remote sites in developing countries under the umbrella of its Sustainable Village Water Systems Program. The students’ professor, Jeffery Chalmers, also collaborates with students to develop strategies for approaching the defluoridation project for better teamwork and design.

“It’s hard to say how long it will take to find a solution,” said Abigail. “We hope that we [the global engineering community] will have a workable solution to this problem within a few years.” Abigail, who took up this challenge as part of her capstone project because she is interested in humanitarian engineering, aspires to work in sustainability and water treatment in the future.

by Nathaniel Kramer, Global Water Institute