Paolo Scardina, a Ph.D. candidate in Virginia Techs Via Department of Civil and Environmental Engineering (CEE), began his research as an undergraduate on the problem of air bubbles in drinking water. Working with Marc Edwards of the CEE faculty, Scardina has continued his research as a masters and doctoral student, and he recently won a highly competitive grant worth $150,000 from the American Water Works Association Research Foundation (AWWARF).

Scardinas research also is being used by engineers with the California Department of Health Services to identify problems at two facilities that have experienced eruptions of air bubbles.

But why would ordinary air bubbles, which occur naturally in water, be a source of concern in drinking water treatment?

"When you open a can of soda, bubbles form and rise to the surface," explains Edwards. "The same thing can happen in water from lakes and rivers. When air bubbles are released in a burp during the treatment process, pathogens and other particles can escape removal."

The last treatment barrier in most drinking water treatment plants is filtration, Edwards says, and a burp of bubbles can punch holes in filterstiny holes, but large enough to let particles and pathogens escape into the water that goes out to customers.

"The field of drinking water treatment is about 3,000 years old," Edwards notes, "but in all that time, air bubbles in water have not been studied in terms of their ability to affect treatment processes."

Scardina, who began studying air bubbles at Edwards suggestion during his senior year at Virginia Tech, identified the causes of bubble formation while he was working on his masters degree. "Before Paolos findings, we knew that bubbles could cause problems," Edwards says, "but we didn
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Contact: Dr. Marc Edwards
edwardsm@vt.edu
540-231-7236
Virginia Tech
5-Oct-2001