By Christina Burchette
What do frozen drinks have to do with EPA research? Water pipe decontamination testing in Idaho!
I’m guessing that you’re probably skeptical or confused by this point. Of course, scientists at the Water Security Test Bed (a full-scale replica of a water distribution system) didn’t actually use sugary ice to decontaminate water pipes—though if sugar could do to pipes what it does to my teeth it would probably be very effective. The reality was a little more complicated than that, but just as fascinating!
To create this slurry, ice was made in two large ice tanks connected to a truck where the mixture was stored. Researchers ran a hose from the truck to one end of the test bed pipe.
Over the Memorial Day weekend, EPA researchers at the test bed did an experiment to see if a method called “ice pigging” could effectively remove anthrax from drinking water systems. Ice pigging is a physical method that scours the insides of the water pipe with an icy mixture called a “slurry,” similar in texture to a frozen margarita.
The difficulty with decontaminating a drinking water system after an anthrax contamination would be that anthrax spores can stick to the inside of pipes and may continuously contaminate water running through the system. Ice pigging could potentially slough off the anthrax spores that remain in the pipes, but the method needs further testing to see if it could be an effective alternative to harsher chemicals typically used to inactivate the spores.
The researchers didn’t actually use anthrax, but instead Bacillus globigii (BG), which is a non-pathogenic anthrax surrogate – it acts like anthrax in the study but doesn’t present the same level of danger.
The ice slurry exiting the pipe into the wastewater holding lagoon
Here’s how the study worked: samples were taken before ice pigging for comparison purposes. Then, researchers stopped the water flow and injected the slurry inside of the pipe to try and physically remove the BG spores. Once the slurry mixture was inside of the pipe, the water was turned back on so the pressure could push the slurry through the pipe to scour it. After all of the slurry had been pushed from the pipe, researchers took more samples. Then, to prepare the pipes for another test, researchers filled the pipes with bleach and let it sit overnight for extra decontamination purposes (and then they sampled again).
The results from this exciting experiment will be out sometime next spring, and the researchers already have several other decontamination experiments planned for the coming months. Personally, I hope they use ice cream next time.
Before I leave, I’d like to give a little plug for the Water Security Test Bed (WSTB): Previous full-scale testing at the WSTB has proved that it’s important for researchers to perform experiments in conditions as close to real life as possible because it can provide better data and insights on decontaminating real water systems than pilot or bench scale experiments—which means that our infrastructure and public health are better protected from emergencies.
EPA invites water sector researchers and other federal agencies to collaborate in ongoing research or initiate new areas of investigation at the WSTB. If you’re interested in partnering with us, please contact Jim Goodrich at goodrich.james@epa.gov.
Watch the video below to learn more about the Water Security Test Bed:
About the Author: Christina Burchette is an Oak Ridge Associated Universities contractor and writer for the science communication team in EPA’s Office of Research and Development.
