As a small child, burgeoning chemist Paige Brown loved to explore the waterways of Maine, her home state. But by the time she was in high school, she realized that — due to reoccurring toxic algae blooms — many of these local waters were in trouble, and dangerous to wildlife and humans.
“What happens is that the algae will block out the sunlight and then later decompose and reduce the dissolved oxygen in the water — preventing fish from surviving,” she says in a talk at TEDxDirigo, “so you’ve got damage to the plants, damage to the fish, and then, most worrying, the algae will start to produce toxins that make the water nearly impossible to drink or use recreationally.”
Seventeen-year-old Brown learned about this process, nutrification, in her chemistry class, and was disturbed by its effects on the environment. “I thought, ‘How many other thousands — or millions — of kids are there around the world who don’t even realize that the water they are playing in could be poisoned?’” she says, a thought that inspired her to take on a summer research project investigating nutrification in Maine.
She built a lab in her parents’ basement and set off to research. For seven months, she collected and analyzed water samples, and discovered a shocking amount of both phosphorous and E. coli in local streams. These results prompted Brown to start looking for solutions to the algae problem.
“I got started on something called a cellulose nanofiber filter mat,” Brown says, “which is basically a fancy word for wood pulp. I was hoping to filter out the E. coli and also absorb the phosphorous … The problem is it didn’t work at all. It failed over and over and over.”
While the filter mat was not a solution to the algae, it gave Brown “clues on where to go next.” And that solution was a bit ironic, she says, a scaffolding made out of calcium alginate, a derivative of algae. This gel, mixed with magnesium–aluminum layered double hydroxide, “absorb[s] massive amounts of phosphorous.”
One gram of this scaffolding (pictured below) can “absorb enough phosphorous to clean two large boiler tanks full of contaminated water in just a few days, for four cents,” Brown says.
To implement this gel-magnesium scaffolding, Brown created a housing system out of a block of foam, hair clips and the sleeve of a T-shirt. The filtration buoys are designed to float in local stormwater retention ponds, absorbing phosphorous from the water.
Once the scaffolding has finished its work, it can be reused as fertilizer, Brown says. “Since the calcium alginate is biodegradable and the phosphorous is absorbed as magnesium phosphate, a major component of fertilizer, [you] can plant [the scaffolding] with crops or houseplants and it breaks down, releases the phosphorous and the plants uptake it slowly, at their own pace.”
Brown’s next project? To add more to the scaffolding — equip it with the power to kill bacteria like E. coli or to absorb lead and other heavy metals.
Watch her entire talk to learn more: