In 2004, 1,4!dioxane was detected in the water supply of a
groundwater treatment plant in Ontario, Canada. With no provincial
regulations for 1,4-dioxane in place, the groundwater plant was
proactively shut down. A treat-ability study was initiated to assess the
suitability of various advanced oxidation process (AOP) technologies
for effective reduction of 1,4-dioxane from the water supply. The study
consisted of a literature review, bench-scale and pilot testing. Three
AOP technologies were tested in this study. These included
UV/peroxide, ozone/peroxide, and UV/titanium dioxide, all of which
were capable of destructing 1,4-dioxane to low or non-detectable
There is a growing problem in the levels of 1,4-Dioxane being found in groundwater. 1,4-Dioxane is not easily adsorbed into soil particles and is difficult to treat because of its high solubility in water. States have different regulations in acceptable levels of 1,4-Dioxane. Alkalinity, chloride, and organics make it difficult for oxidation treatment to break down 1,4-Dioxane.
An experiment was done in which a high concentration of 1,4-dioxane (300 and 3000 ug/L) and chloride (80 mg/L) were added to water taken from a well. Three advanced oxidation process (AOP) solutions were tested to measure their effectiveness. They included UV/peroxide, ozone/peroxide, and UV/titanium dioxide. Three levels of ozone/peroxide were analyzed: low, medium, and high with hydrogen peroxide levels remaining constant. Samples were taken after treatment and analyzed.
All three AOP technologies tested reduced 1,4-dioxane to acceptable levels. The combination of ozone/peroxide demonstrated the ability to destroy 1,4-dioxane in the well without producing bromate by-product. Figure 7. shows the effectiveness of all three AOP technologies in removing 1,4-Dioxane.
L. Wojcicka, E. Edwards, J. Cavalcante, N. Kodousek, R. Hoffman
Associated Engineering, Suite 800, 304 The East Mall, Toronto, ON, Canada, M9B6E2
Regional Municipality of Waterloo, 150 Frederick St, 7th fl, Kitchener, ON, Canada, N2G4J3
Andrews, Hofmann & Associates, 203 College St, Toronto, ON, Canada, M5t 1P9