In searching the literature about water treatment, Scardina noticed that serious problems often occurred at plants that experienced air bubble eruptions. "We thought this path was worth investigating," he says.

In addition to studying why bubbles form and how they punch holes in treatment plant filters, Scardina has made some discoveries. Air bubbles can interfere with the first drinking water treatment processsettlingwhere solid particles from incoming surface water drop to the bottom of treatment tanks. "If bubbles are present at this stage," Scardina notes, "pathogens and other particles can attach to them and float on through the treatment plant."

Another important discovery by the Virginia Tech student is that bubbles can cause a dilemma for treatment plant operators at the end of the process. "When bubbles form after water has gone through filtration, water quality tests may wrongly identify the bubbles as dirt particles or pathogens, even though the bubbles themselves are harmless," Edwards says. "This decreases the validity of and confidence in water quality tests."

While a masters candidate, Scardina published two peer-reviewed papers on his findings and made a presentation at an international water treatment conference in London. "Paolos subject area is so new that we had a hard time finding people with enough knowledge of the field to review his papers," Edwards remarks.

On September 20, the Mendocino District Office of the California Department of Health Services flew Scardina to the West Coast to help engineers there identify the source of air bubble eruptions that have occurred at two water treatment plants. "Paolo is doing some very important work," says Guy Schott, associate sanitary engineer for the Mendocino District.

Schott found out about Scardinas work from Edwards, with whom he had collaborated in the past. Scardina sent his graduate papers a
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Contact: Dr. Marc Edwards
edwardsm@vt.edu
540-231-7236
Virginia Tech
5-Oct-2001