1,4-Dioxane Oxidation

The problem:  Site groundwater contained approximately 600 µg/L 1,4-dioxane and on the order of 500 µg/L TCE and other VOCs.  The client was considering ozone for in situ chemical oxidation, but was uncertain whether ozone alone could destroy 1,4-dioxane since advanced oxidation (ozone plus peroxide) was generally believed necessary for treatment of this constituent.

How PRIMA helped:  PRIMA performed laboratory tests to compare the ability of ozone and ozone plus hydrogen peroxide to destroy 1,4-dioxane present in site groundwater.   Sparging groundwater with ozone reduced the aqueous concentration of 1,4-dioxane from 680 µg/L to < 3 µg/L. The same results were achieved by treating with ozone plus hydrogen peroxide.  Based on the results, additional tests were performed to determine which component(s) of groundwater could be enhancing the effectiveness of ozone.  The tests were performed using deionized (DI) water spiked with 1,4-dioxane to which an enhancer was added.  Ozonation of spiked DI water (no enhancer) resulted in destruction of 75% of the 1,4-dioxane, while ozonation (same conditions) of spiked DI water plus an enhancer produced complete destruction.  The enhancers tested were:  ferrous iron (2 mg/L), chelated iron (2 mg/L iron), and alkalinity (1000 mg/L as CaCO₃).  These results imply that although ozone alone can destroy 1,4-dioxane, compounds naturally present in site groundwater can enhance the effectiveness of ozone in the same manner that hydrogen peroxide does.

For more information about this project, see our poster “In situ Oxidation of 1,4-Dioxane”  on our Resources– Webinars and Presentations page.