TREATABILITY OF MTBE-contaminated groundwater BY OZONE AND PEROXONE

A combination of ozone and hydrogen peroxide (known as peroxone) was studied as a treatment alternative for removing methyl tertiary butyl ether (MTBE), a common fuel oxygenate. The authors investigated the effects of oxidation of ozone and peroxone on MTBE in Santa Monica, Calif., groundwater. Experiments conducted in a large‐scale, semibatch reactor demonstrated that peroxone (at a peroxone ratio of 1.0, with applied ozone doses of ≤10 mg/L) was more consistently effective in oxidizing MTBE than was ozone alone. To achieve MTBE levels below the California secondary standard of 5 μg/L for drinking water, however, applied ozone doses of > 10 mg/L would be necessary for spiked MTBE concentrations of approximately 200 and 2,000 μg/L. Both ozone and peroxone can degrade MTBE into biodegradable products such as t‐butyl formate, t‐butyl alcohol, acetone, and aldehydes (including formaldehyde, acetaldehyde, heptaldehyde, glyoxal, and methyl glyoxal). In addition, peroxone can oxidize MTBE more rapidly than can ozone alone. When peroxone was used, the concentrations of bromate formed ranged from nondetected to 13 μg/L (in water containing ~0.3 mg/L bromide), exceeding the maximum contaminant level of 10 μg/L. Results indicated that bromate formation could be effectively controlled with hydrogen peroxide‐to‐ozone ratios > 1.0.