Destruction of 1,4-Dioxane and VOCs with UV-H2O2 in a high alkalinity groundwater

Bench-scale testing was conducted to evaluate the application of an Ultraviolet-hydrogen peroxide (UV-H₂O₂) advanced oxidation process (AOP) for the destruction of 1,4-Dioxane (47 μg/L) and varying concentrations of three volatile organic chemicals (VOCs), including trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1-dichloroethylene (1,1-DCE), from three samples of groundwater containing high alkalinity (281 mg/L as CaCO₃). The UV doses applied ranged from zero to 5500 mJ/cm² while the H₂O₂ concentrations ranged from 0 to 16 mg/L. The results showed that the bicarbonate and carbonate alkalinity greatly dominated the hydroxyl radical consumption and thus the 1,4-Dioxane destruction rate. The removal of perchlorate, chlorate, and nitrate prior to UV-H₂O₂ treatment had no discernable effect on 1,4-Dioxane destruction, while the removal of TOC increased the rate of 1,4-Dioxane destruction by approximately 25%. Depending on the combination of H₂O₂ concentration and UV dose, 1,4-Dioxane destruction ranged from negligible to greater than 99%.