Curbing pollution, saving agriculture

by Zeke Barlow

When farmers on Virginia’s Eastern Shore were told they had to curb the amount of nitrogen and phosphorous seeping from their fields into the Chesapeake Bay, Zach Easton stepped in to find a solution.

Zach Easton, left, an assistant professor of biological systems engineering, explains how his new bioreactor curbs pollution in the Chesapeake Bay to Mary Leigh Wolfe, head of BSE, and Saied Mostaghimi, the college’s associate dean for research and graduate studies.

Easton, an assistant professor of biological systems engineering, may have found a way to save the bay while maintaining farmers’ profits with the development of a bioreactor buried under the coast’s fertile agricultural grounds.

“The ultimate hope is that this will be a cost-effective system that producers can use to protect water quality and help keep agriculture profitable in Virginia,” said Easton, who is a Virginia Cooperative Extension specialist located at the Eastern Shore Agricultural Research and Extension Center. Virginia Tech’s Institute for Critical Technology and Applied Science also provided funding for the project.

Regulations mandate that farmers curb their nitrogen and phosphorous in groundwater by as much as 30 percent. Easton’s new bioreactor surpasses that by removing up to 90 percent of the nitrogen and 45 percent of the phosphorus. It costs about $260 an acre — a one-time expense over its 20-year lifespan, which is much cheaper than some other solutions.

The bioreactor is a large vat buried underground that is filled with woodchips. Water from the fields is funneled toward the container, where microorganisms feed off the wood chips and nutrients in the water. Because it is buried underground, there is little loss of productive land.

During the feeding process, the microorganisms convert  nitrogen in the water into harmless nitrogen gas, which makes up 78 percent of the atmosphere. They also incorporate the phosphorus into their microbial biomass. The added substrate, biochar, can also remove phosphorus from the water.

Easton and BSE graduate student Emily Lassiter are examining the bioreactor to make sure it is producing inert gasses that are not harmful to the atmosphere.

“We don’t want this to have adverse downstream consequences,” said Lassiter, of Onley, Va.

Easton said they hope to have a market-ready bioreactor by next year. When it is ready, its applications could extend well beyond the Chesapeake Bay.

“We believe this is an economic and viable solution to curb water pollution while protecting farmers’ bottom lines,” he said.