USF researchers test filtration system to remove pollutants from stormwater runoff

An interdisciplinary team of researchers from the University of South Florida has secured a three-year, US$1.5 million grant from the US Environmental Protection Agency to prevent pollution from seeping into a local stormwater pond that flows into Tampa Bay and the Gulf of Mexico.

Aaran's Pond in Tampa, Florida
Aaran's Pond in Tampa, Florida - Credit: University of South Florida.

The USF team is installing a bio-infiltration system at Aaran’s Pond in Tampa’s University Area Community, where more than one in three residents live below the federal poverty level.

According to principal investigator Professor Sarina Ergas in the USF Department of Civil and Environmental Engineering, when it rains, the water washes pollutants, such as fertilizer, oil, animal waste and rotting vegetation into gutters, which then feed into an existing stormwater pond. For that reason, urban runoff is a challenging problem to address in underserved communities, especially as stormwater ponds are often full of trash and difficult to clean due to restrictive fencing and steep slopes.

“We’re calling them inert zombies due to their lack of life,” Ergas said. “If you look at the difference between a stormwater pond in a wealthy neighborhood and one in a low-income neighborhood – it’s day and night in terms of how they benefit the community.”

If those pollutants are not removed from the ponds, they eventually cascade into the Hillsborough River and Tampa Bay, which feeds into the Gulf of Mexico. Nutrients, such as nitrogen, create harmful algal blooms, kill sea grass and reduce oxygen in the water.

The team is partnering with Oldcastle Infrastructure to install four new bio-infiltration systems around the pond to improve the nutrient removal. The systems will retain and treat the runoff water with biochar that will help reduce the nutrient pollution and increase microbial activity and plant growth.

Previous studies with biochar have taken place in the lab, but this is the first time it is being used in a pond to improve water quality.

The USF team is collaborating with Mary Lusk, a University of Florida expert in stormwater ponds and their functions, to redesign the pond with the Hillsborough County Engineering and Operations Department. The plan is to plant bio-infiltration systems with shrubs and bushes along the steep slopes to provide additional filtration and make the pond more visually appealing.