Cleaning up the environment

Zhiming Zhang, an assistant professor of civil and environmental engineering in the Henry M. Rowan College of Engineering, devises methods for removing these and other substances from soil and water.

When picked up and transported by stormwater, PFAS can enter drinking water sources. In studies of New Jersey stormwater runoff, he and colleagues identified multiple PFAS compounds, among which the concentrations of PFOA and PFOS exceeded many times over the U.S. Environmental Protection Agency’s four parts-per-trillion maximum contaminant level for drinking water. Meanwhile, his group is testing ways to remove these contaminants, including breaking them down with bacteria or specialized oxidation treatments. They are also experimenting with filtering PFAS out of water by, for example, binding them onto materials leftover from the treatment of drinking water, which would otherwise go to a landfill.

Separately, his group is extracting lead from soil with vetiver grass along with the use of biodegradable agents that aid this process. Over three years, this method cut the lead in a community garden plot in Jersey City down to about one-fourth its original concentration. After completing a remediation project like this one, they recycled the plants’ lead-containing roots by turning them into a type of charcoal known as biochar that then can be used to filter contaminants (e.g., heavy metals) from wastewater. The leaves, which uptake very little lead, are used to make bioethanol, a type of fuel. The use of the entire vetiver plant after soil lead extraction aims to form a circular economy model.

“We try to minimize waste and make the most use of the resources we have during the environmental protection process” Zhang says.