July 25, 2005

Purifics awarded U.S. contract to treat 1,4-dioxane in groundwater

Purifics ES, a London, Ontario company specializing in air and water treatment systems and technologies, has received a contract to supply its Photo-Cat (ultraviolet (UV) photocatalytic) system for the treatment of 1,4-dioxane in groundwater at a site in the U.S.

The Photo-Cat system will be positioned downstream from an existing ten-year-old pump-and-treat installation consisting mainly of an air stripper for the removal of chlorinated solvents. Operating at a flow rate of 25 gallons per minute (gpm), the Purifics system will produce high-quality treated water, destroying 1,4-dioxane to levels below detection limits.

As an added safeguard, the company notes that the Photo-Cat system will destroy any residual chlorinated solvents that escape from the air stripper. This, says Purifics, is an example of a newly discovered problem (i.e. the presence of 1,4-dioxane) in an existing remediation treatment train. The installation will be completed by the end of August.

1,4-dioxane has been widely used with chlorinated solvents, particularly 1,1,1-trichloroethane (TCA), as a stabilizer and corrosion inhibitor. When 1,4-dioxane is used as a solvent stabilizer, the solvent itself is regulated as hazardous waste by the U.S. Environmental Protection Agency (EPA).

The compound is highly miscible in water; in fact, it mixes with water so readily that it can be found in groundwater plumes far in advance of any solvents with which it might have entered the subsurface originally. It also migrates rapidly in soil. 1,4-dioxane contamination often can be found in association with releases of chlorinated solvents.

EPA has listed the compound as a probable human carcinogen based on the results of animal studies, but little information is available on the long-term effects of 1,4-dioxane on human health.

The compound does not respond to air stripping or granular activated carbon treatment, nor does it biodegrade in the subsurface other than very slowly. Successful results have been obtained using processes involving hydrogen peroxide and ultraviolet light or ozone. Phytoremediation also shows promise for its removal at depths accessible to plant roots.

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