MOUNT VERNON — Answers remain elusive to the City of Mount Vernon’s long-standing problem with the occasional spotting of laundry. The spotting, which can leave a bleach-like mark on clothes, has defied solution for over a decade and a half, according to Judy Scott, administrator of Treatment and Distribution for the Water/Wastewater Department.
“That’s a common misconception, that it is bleach,” Scott said, explaining that no bleach goes into the city’s water.
The purification system actually uses a generator which combines chlorine gas with sodium chlorate to create chlorine dioxide, a substance too unstable to be shipped in its pure state. This chemical is safe to humans when diluted into large quantities of water, where it disinfects and purifies. Strictly speaking, Scott said, bleach is a different chemical, although many of the uses of chlorine dioxide bear a similarity to the uses for bleach.
Scott said that in the purification system, the elements are combined to form the gas, which is then injected into the water. From there it goes to a large clear well holding tank with baffles that slowly, gently stir the water to achieve the proper mixture. Scott said laundry studies have found that the spotting problem is so inconsistent, it is hard to attribute it to the purification chemicals.
“We don’t know what exactly it is,” Scott said, inviting the public to review highlights of the studies, links to which can be found on the city’s Web page at www.mountvernonohio.org.
Scott said if there were a chemical problem, one would expect the problem to be more widespread and consistent, but surveys of residents have found that the problem can affect as little as one item in a load of laundry, instead of the whole load. The studies found the problems have an overwhelming tendency to involve dark colors, and cotton or cotton-blend clothes.
Retired chief of metallurgy at Cooper Industries, William Ferguson, has developed a theory, applying his knowledge of fluid mechanical engineering.
“It’s my conclusion that it is a mixing problem,” Ferguson said, pointing out that the problem isn’t heard about in Gambier, suggesting that perhaps the water and gas are better mixed by the time they move out to the fringes of the water system.
Ferguson compared the mixing process to a tube of Aqua-Fresh brand toothpaste. The paste comes out of the tube in stripes of different colors because it hasn’t been mixed together.
Turbulence is needed for thorough mixing, but Ferguson said steady, calm laminar flow is needed to send the purified water throughout the system without damaging pipes. His theory is that perhaps the point where the chlorine dioxide is introduced into the water should be lengthened or spread out through more than one injection point to help the water get more thoroughly mixed. And, he added, it wouldn’t be very expensive to try a few options, such as extended addition points, or to run a test with dyed water to visually observe how it mixes and flows.
Ferguson has advanced preliminary versions of his theory to city officials, but said he is still hoping to learn more about the system in hopes of solving the spotting conundrum.