A Fresh Look At Water Treatment
by David Pescovitz
 Printer-friendly
version
While on his Fulbright fellowship in Sydney, Australia, David Sedlak also learned to surf.
|
It's a do or dry situation for Australia's national water shortage. According to the Australian Water Services Association, the country is facing a 275 gigaliter shortage of drinking water in the next ten years unless drastic conservation measures and new treatment methods are put into place. To UC Berkeley professor David Sedlak, the situation is similar to California's own water problems, only much worse. During a Fulbright fellowship last year at the University of New South Wales, Sedlak helped develop a novel treatment technique that could aid in the purification of contaminated water and increase drinkable resources down under.
"There are a number of ways to treat groundwater or soil that's contaminated with organic pollutants like pesticides," Sedlak says. "The problem is that many of these methods are too expensive and relatively inefficient."
When Sedlak arrived in Australia, he was startled by a recent discovery by graduate student Sung Hee Joo's that had the potential to dramatically improve a time-tested technique of water treatment. Joo had observed that nanoscale particles of iron, when exposed to oxygen in contaminated water, become a powerful oxidizing agent that completely degrades the pesticides.
Sprinkling contaminated water or soil with iron filings scavenged from industrial trash is nothing new, Sedlak says. The filings act as a reductant, transferring electrons to the pollutant and thereby transforming the contaminant into a less-toxic form. The process is commonly used to clean up groundwater tainted by dry cleaning chemicals. However in Australia, the researchers determined that the iron nanoparticles transfer electrons to the oxygen, producing a reactant that, in turn, oxidizes the contaminants and purifies the water much more completely.
David Sedlak and Sung Hee Joo at the University of New South Wales. (courtesy UNSW)
|
Now, Sedlak, Joo, and their collaborators are taking a deeper look at the reaction to understand the chemical mechanisms involved. They're determining how well the technique works on contaminants such as benzene and the gasoline additive methyl tertiary-butyl ether (MTBE). The work could also be extended to water treatment systems for the oxidation of arsenic. Through a series of laboratory experiments, they hope to identify the best-suited real world applications of the technology.
"One approach could be to apply the nanoparticles to contaminated soil or shallow groundwater directly so it could use the oxygen that's already present to react with the contaminants," he says.
Another possibility is to use the nanoparticles to augment the purification process at more traditional water treatment facilities. At these plants, a mineral coagulant is often used to help settle out the polluting particles. Sedlak suggests that the iron nanoparticles could do double duty, first acting as an oxidizing agent and then forming the coagulant.
Back at Berkeley, Sedlak has had a bit of time to reflect on the different ways Australians and Californians are dealing with a drought of life's most vital fluid.
"In California, we prefer to solve our water problems with big approaches like dams, high-tech treatment plants, and new water recycling facilities," Sedlak says. "In Australia, the public thinks more locally, down to collecting roof runoff to water their gardens. Hopefully, in the near term we'll also start thinking more about local solutions to our water shortage."
David L. Sedlak's home page
"Researchers discover new treatment for pesticides" (University of New South Wales, 2 March 2004)
Lab Notes is
published online by the Marketing and Communications Office of the UC Berkeley
College of Engineering. The Lab Notes mission is to illuminate groundbreaking
research underway today at the College of Engineering that will
dramatically change our lives tomorrow.
Media contact: Teresa
Moore, Lab Notes editor, Director of Marketing and Communications
Writer, Researcher: David
Pescovitz
Web Manager: Michele
Foley
Subscribe or send comments to the Engineering Marketing and Communications Office: lab-notes@coe.berkeley.edu.
© 2005 UC Regents.
Updated 2/1/05.
|
