In many areas, localized releases of industrial chemicals, pesticides, petroleumadditives such as MTBE. and fuel components such as benzene and hydrazine. have impaired groundwater quality. These groundwater 'plumes' are commonplace, and in many cases impact public water supplies or impedes the redevelopment of potentially valuable land.
There are approximately 12,000 sites listed as Superfund sites in the United States, of which over 1,000 are deemed National Priority List (NPL) sites. The NPL is a list of sites determined to pose the greatest threat to human health or the environment. Often, contaminated sites require the removal and treatment of contaminated water in order to contain a “plume” of contamination. Ex-situ treatment is often required to treat discharge water to high water quality standards.
Many chemicals such as NDMA, 1,4-dioxane and MTBE cannot be removed cost-effectively by conventional technologies such as carbon adsorption or air stripping. Often, mixtures of contaminants require multiple treatment steps, including UV-oxidation, to achieve discharge requirements.