Ed Weinberg thinks he has developed the best way to stop the toxic blooms of blue-green algae that have been fouling bodies of water from the Florida Everglades to the Great Lakes and beyond.

The algae feed on phosphorus from farms and wastewater treatment plants that makes its way into rivers and lakes. Mr. Weinberg’s solution deploys tiny beads of engineered resin that can absorb the mineral from water and extract it for reuse.

“It’s simple yet elegant chemistry,” said Mr. Weinberg, a chemical engineer who is among the finalists in a $10 million competition that is one of a number of both public and private efforts to solve a growing problem in U.S. waterways.

Researchers are racing to find solutions to outbreaks of blue-green algae that are increasing in frequency and severity. Carpets of stinking algae have sickened people and animals and hurt the fishing and tourism industries.

In 2014, the drinking water for nearly half a million people in Toledo, Ohio, was contaminated by the toxin microcystin produced by the algae.

“When you’re dealing with an issue as large and complex as we are right now, the more solutions the better,” said Christopher Winslow, who coordinates federal- and state-funded research into algal blooms at Ohio State University. He isn’t involved in the competition, which is privately run.


So far, research has been focused in four main areas, Mr. Winslow said: removing toxins from water, understanding how toxins affect the human body, understanding how blooms grow and preventing blooms in the first place.

Stopping the blooms is taking on more urgency. In March, the Environmental Protection Agency announced a plan to meet a goal of cutting phosphorus entering Lake Erie by 40% through voluntary efforts by 2025. Also last month, Ohio declared the shallow western basin of Lake Erie “impaired,” a step toward tighter regulations of phosphorus from farms and wastewater plants.

Algal blooms in Lake Erie were a problem in the 1960s. The blooms faded after regulations were implemented that required wastewater treatment plants to cut phosphorus.

But in the mid-1990s the blooms returned, and they have been surging more recently. Today, scientists point to farm runoff as a major cause of blooms.


For Lake Erie, the Maumee and Sandusky rivers are the greatest contributors of phosphorus, with 87% of phosphorus coming from sources that include farms. Environmental groups want tighter limits on use of fertilizer, which typically contains phosphorus.

Algae in the Maumee River at the mouth of Lake Erie in September. Photo: /Associated Press

“It’s time for the foot-dragging to come to an end,” said Howard Learner, president of the Environmental Law & Policy Center, based in Chicago, which sued the state of Ohio in federal court last year, arguing it should declare Lake Erie impaired. A ruling in that case is pending. “We know what causes it. It’s manure and excess fertilizer.”

Joe Cornely, a spokesman for the Ohio Farm Bureau Federation, said farmers are already taking steps to manage fertilizer more effectively. “We recognize that more needs to be done,” he said. “Our approach is, as soon as we figure out something that we know is going to work, let’s take that step.”

Researchers are exploring a variety of solutions. Some are working on ways to remove phosphorus from manure directly. Others are testing materials that could be inserted in drainage tiles under the soil on farms to remove phosphorus before it reaches rivers.


Mr. Weinberg, a 66-year-old from Richboro, Pa., outside Philadelphia, wanted a site with plenty of manure to test his technology last fall. He found a horse farm in Maryland with a pond thick with algae. He filled burlap sacks with his beads and put them in open crates, creating a makeshift filter in a drainage creek that flowed into the Chesapeake Bay.

He said he was able to replicate his lab results for removing phosphorus, and said there is no reason his technology couldn’t be applied at commercial farms in Ohio where phosphorus eventually makes its way into Lake Erie.

The competition in which he is a finalist is offering a $10 million prize for the best phosphorus-removal technology. It is sponsored by the nonprofit Everglades Foundation and the Scotts Miracle-Gro Foundation, a charitable organization affiliated with the fertilizer company.

The numbers of teams competing have been winnowed from more than 100 from 13 countries, to 10 from the U.S., Canada, the Netherlands and China, according to officials working on the competition.


Write to Kris Maher at kris.maher@wsj.com