US high schoolers design low-cost filter to remove lead from water

When the pandemic forced schools into remote learning, Washington-area science teacher Rebecca Bushway set her students an ambitious task: design and build a low-cost lead filter that fixes to faucets and removes the toxic metal.

Using 3D printing and high-school level chemistry, the team now has a working prototype -- a three-inch (7.5 centimeter) tall filter housing made of biodegradable plastic, which they hope to eventually bring to market for $1 apiece.

"The science is straightforward," Bushway told AFP on a recent visit to the Barrie Middle and Upper School in suburban Maryland, where she demonstrated the filter in action.

"I thought, 'We have these 3D printers. What if we make something like this?'"

Bushway has presented the prototype at four conferences, including the prestigious spring meeting of the American Chemistry Society, and plans to move forward with a paper in a peer-reviewed journal.

Up to 10 million US homes still receive water through lead pipes, with exposure particularly harmful during childhood.

The metal, which evades a key defense of the body known as the blood-brain-barrier, can cause permanent loss of cognitive abilities and contribute to psychological problems that aggravate enduring cycles of poverty.

A serious contamination problem uncovered in Flint, Michigan in 2014 is perhaps the most famous recent disaster -- but lead poisoning is widespread and disproportionately impacts African Americans and other minorities, explained Barrie team member Nia Frederick.

"And I think that's something we can help with," she said.

The harms of lead poisoning have been known for decades, but lobbying by the lead industry prevented meaningful action until recent decades.

President Joe Biden's administration has pledged billions of dollars from an infrastructure law to fund the removal of all the nation's lead pipes over the coming years -- but until that happens, people need solutions now.

Bushway's idea was to use the same chemical reaction used to restore contaminated soil: the exposure of dissolved lead to calcium phosphate powder produces a solid lead phosphate that stays inside the filter, along with harmless free calcium.

The filter has a clever trick up its sleeve: under the calcium phosphate, there's a reservoir of a chemical called potassium iodide.