Published on June 26, 2024
Written by Julia Davis for the University of Washington
In cities around the globe, stormwater runoff remains largely untreated, collecting everything from heavy metals to pesticides before flowing into our waterways. This environmental challenge requires innovative solutions, and biochar may just be the key.
CEE Assistant Professor Jessica Ray and graduate student Amy Quintanilla are exploring how this sustainable material, made from recycled food waste, can not only integrate with natural environments, but also effectively filter out harmful contaminants from stormwater. Their research presents a potential solution to tackling urban water pollution, offering hope for healthier ecosystems and safer water sources.
Stormwater is a leading cause of nonpoint source pollution in urban watersheds, according to Ray, who is the Robert O. and Irene V. Sylvester Family Endowed Professor in Water Resources. But most cities have no formal treatment process for it. This runoff collects contaminants as it flows across city surfaces, from roads to rooftops, before discharging into rivers and oceans largely untreated. The implications of this process are far-reaching, affecting water quality, wildlife and human health.
At the heart of Ray and Quintanilla’s research lies biochar, a black charcoal-like substance rich in carbon and made by burning organic materials at high temperatures in an environment with limited oxygen. Biochar can be made from a variety of waste products. Ray’s research relies on biochar that her team makes in the lab using recycled coffee grounds from campus coffee suppliers.
The key characteristic that makes biochar so effective in environmental applications is its highly porous structure, which provides a large surface area for the adsorption of pollutants. By converting waste into biochar, not only is the volume of waste reduced, but its transformation into a beneficial product contributes to a mutually beneficial cycle, turning potential pollutants into tools for environmental remediation.
“The biochar that we’re designing is specifically targeted to filter out the contaminants we find most harmful in stormwater,” Ray says.
This tailored approach ensures that biochar is highly effective at capturing pollutants like heavy metals and “forever chemicals” like PFAS, which are prevalent in urban runoff and never break down in the environment.
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In cities around the globe, stormwater runoff remains largely untreated, collecting everything from heavy metals to pesticides before flowing into our waterways. This environmental challenge requires innovative solutions, and biochar may just be the key.