Searching for cheaper, better ways to treat hazardous waste has become a preoccupation for industry. Today, contaminated groundwater at Superfund sites is cleansed by pumping it out of the ground, filtering it, and sending it to a wastewater plant for final treatment. That's an expensive process--and one that researchers at Stanford University now suggest could be done right in the ground, using air bubbles.
The new method, developed by geologists Steven M. Gorelick and Haim Gvirtzman, would use air injected into wells to keep groundwater circulating, the way an aeration unit in a fish tank works. Volatile organic compounds, such as benzene and carbon tetrachloride, would be attracted to the air bubbles and transported as gases to the surface, then vacuumed off and filtered, while the water remains below. Theoretically, this would save millions of dollars in transportation and energy costs. Stanford has patented the process, and along with partner Pacific Northwest Laboratories is seeking government approval to test it at a tainted site near Hanford, Wash.