Testing Water, Drops at a Time

June 07, 2004

A&M scientists working to improve monitoring methods.

Texas A&M University microbiologist, Suresh Pillai has spent years trying to collect a reliable test sample that is representative of a huge amount of water.

This has been an ongoing problem for water utilities and the food and beverage industry. Because of America's need to built a better defense against terrorism such as a biological attack on a major city's water system, scientists will need to be able to quickly identify what organisms or agents are present.

Ali Beskok, a mechanical engineer at the university in College Station, has proposed a solution: Create a device that corrals harmful bacteria and viruses and removes them from a large quantity of water, then concentrates them for a more accurate test sample, according to the Houston Chronicle Washington Bureau.

The researchers say the key may be electricity. Fecal viruses and bacteria, including E. Coli and salmonella, are negatively charged on their surfaces. A positively charged electrical field, therefore, theoretically could be used to herd the pathogens into a container, where they can be concentrated into smaller samples for testing.

"We are looking for a needle in a haystack," Beskok said. "So the idea is to pass through every hay particle and find the needle."

After two years of work, under a $129,000 grant from the state of Texas, the researchers think they are on the verge of proving their hypothesis. Now NASA is paying $89,000 to find out whether they're right.

If they are, scientists could one day use Beskok and Pillai's device to continually, and much more accurately, monitor drinking water supplies, rather than relying on "grab samples" -- small volumes of water collected to spot check a larger supply.

The NASA grant, awarded this year, will fund a pilot project to build the device, which would channel about 5 liters of water per hour through hundreds of parallel tubes in a glass or Plexiglas container. The tubes each would be about a quarter of a millimeter wide to ensure that any microbes would pass close enough to electricity conducted by a copper plate, reported the Houston Chronicle Washington Bureau.

Once the microbes were collected and concentrated, bacteria and viruses from dozens of liters of water would be trapped in about a milliliter of water – about a thimbleful – which then could be tested.

The device would be designed to collect any pathogen that might be in the water, rather than targeting certain bacteria or viruses.

"That is a strength here," Beskok said. "One device will capture everything."

Source:

Houston Chronicle Washington Bureau

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