BERKELEY, CALIFORNIA — December 11, 2019
Baseball fans may be excited to have combination pitcher/slugger Shohei Ohtani on the Los Angeles Angels, but new research suggests that he isn’t the only dual threat that could help out Southern California. UC Berkeley engineers have discovered a mineral-coated sand that can soak up toxic metals like lead and cadmium from water. Along with its ability to destroy organic pollutants like bisphenol A, this material could help cities tap into an abundant but under-used water source: storm water.
Researchers knew that the naturally-occurring minerals they coated onto sand could react with organic contaminants like pesticides in storm water. However, its ability to also remove harmful metals during filtration could unlock urban water supplies that had been written off. Cities with Mediterranean climates, like Los Angeles, could store storm water underground during wet winters, where it could serve as an inexpensive, local supply during the dry season. But this resource has gone mostly untapped because storm water picks up toxic chemicals as it runs through streets and gutters.
“The pollutants that hold back the potential of this water source rarely come one-at-a-time,” said Joe Charbonnet, the paper’s lead author. “It makes sense that we fight back with a treatment technology that has these impressive double abilities to take out both toxic metals and organics. We suspected that the mineral-coated sand was special, but it the way it continues to impress with multiple capabilities is rather extraordinary.”
Cities often discard storm water as pollution because it picks up contamination like lead particles left behind from decades of leaded gasoline emissions or pesticides from lawns. Exposure to these chemicals can slow neurological development children and can cancer. However, researchers say that their coated sand material could be installed in rain gardens in places like parking lots where storm water can be collected and cleaned. They estimate that this material could remove metals from storm water for over a decade in a typical infiltration system. Particularly in parched cities that pay to import water, the researchers see this material turning pollution into a solution for strained water supplies.
“Rainwater used to percolate into the soil and recharge aquifers,” said David Sedlak, professor of civil and environmental engineering at UC Berkeley and co-author of the paper. “That changed when we covered city landscapes with hard surfaces like roads and buildings. As water-stressed cities try to figure out how to get urban storm water back into the ground, we have serious concerns about the quality of that water. Our coated sands can remove not one, but two major classes of contaminants that threaten groundwater quality during storm water infiltration.”
To make the filtration media, the scientists coated sand particles with manganese oxide, a naturally-occurring nontoxic mineral commonly found in soil. Work has already begun to investigate how well this material performs at large scales. Researchers have deployed large test columns of the mineral-coated sands to treat stormwater at sites in Los Angeles and Sonoma, CA.
The team’s findings were published December 5 in Environmental Science: Water Research & Technology.
Paper Title: “The Use of Manganese Oxide-Coated Sand for the Removal of Trace Metal Ions from Stormwater”
For a manuscript, email [email protected].
Available for Interviews:
- Joe Charbonnet, Ph.D., UC Berkeley & Green Science Policy, T: (352) 275-2569; email: [email protected]
- David Sedak Ph.D., UC Berkeley, T: (510) 643-0256; email: [email protected]
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