Treatability of Mtbe‐contaminated groundwater by Ozone and Peroxone

Abstract

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.

Chemical and toxicological evolution of the antibiotic sulfamethoxazole under ozone treatment in water solution

“…The initial concentration of SMX in ozonated samples was 0.150 mM. This hydrogen peroxide flow was chosen to keep the overall H 2 O 2 /O 3 molar ratio below 0.5, which corresponds to the overall stoichiometry of the O 3 /H 2 O 2 reaction, thereby avoiding an excess of hydrogen peroxide and the subsequent hydroxyl radical scavengers [17][18][19]. pCBA was used as probe compound to assess the presence of hydroxyl radicals in the reaction mixture.…”

In SituChemical Oxidation

“…Bromate is a chemical that is formed during the ozonation of natural waters where bromide is present. In environments with a high bromide content such as seawater, bromide concentrations are approximately 65 mg/l (Acero et al, 2001;Chang and Yen, 2000;Liang et al, 2001;West Hertfordshire Health Authority, 2001). The USEPA has set the MCL for bromate at 0.010 mg/l because toxicology studies have shown bromate to be carcinogenic in laboratory animals (USEPA, 1998).…”

“…During laboratory studies, Liang et al (2001) found that 0 3 alone caused an increase in bromate concentration, but with peroxide to 0 3 ratios of greater than 1.0, a decrease in bromate concentration was realized. Liang et al (2001) determined that the H 2 0 2 in the peroxone treatment reduced aqueous bromine to bromide, resulting in low yields of bromate.…”

“…Liang et al (2001) determined that the H 2 0 2 in the peroxone treatment reduced aqueous bromine to bromide, resulting in low yields of bromate. In a similar study, Acero et al (2001) surmised that, even at concentrated levels, H 2 0 2 cannot completely suppress bromate formation, but the presence of H 2 0 2 leads to reduced hypobromous acid concentrations.…”

“…drastically increases the oxidative capabilities of the ISCO system (Liang et al, 2001;Mitani et al, 2001;Acero et al, 2001). Five frequently used oxidants are reviewed in this chapter and include: hydrogen peroxide (H 2 0 2 ), ozone (03(g))' permanganate (Mn04 -), persulfate (S20i-), and ultrasound.…”