University of California, Berkeley, engineers have created a new way to remove contaminants from storm water, potentially addressing the needs of water-stressed communities that are searching for ways to tap the abundant and yet underused source of fresh drinking water.
Using a mineral-coated sand that reacts with and destroys organic pollutants, the researchers have discovered that the engineered sand could help purify storm water percolating into underground aquifers, creating a safe and local reservoir of drinking water for parched communities.
“The way we treat storm water, especially in California, is broken. We think of it as a pollutant, but we should be thinking about it as a solution,” said Joseph Charbonnet, a graduate student in civil and environmental engineering at UC Berkeley. “We have developed a technology that can remove contamination before we put it in our drinking water in a passive, low-cost, non-invasive way using naturally-occurring minerals.”
As rain water rushes over our roofs, lawns and streets, it can pick up a slew of nasty chemicals such as herbicides, pesticides, toxic metals, car oil and even dog poop. Excess storm water can also overwhelm sewer systems and flood streets and basements. Not surprisingly, cities often discharge this polluted water into neighboring rivers and streams as quickly as possible.
Directing storm water through sand into underground aquifers may be an ideal solution for gathering water in cities with Mediterranean climates like Los Angeles, Charbonnet said. Like giant rain barrels, aquifers can be filled during periods of intense rainfall and then store water until it is needed in the dry season.
Cities are already using storm water reclamation on smaller scales through constructs such as bioswales and rain gardens, which funnel storm water through sand or mulch to remove debris and prevent surface runoff. In the Sun Valley neighborhood of Los Angeles, Charbonnet and his adviser, David Sedlak, are working with the local community to transform a 46-acre gravel pit into a wetland and water infiltration system for storm water.