Oxidation of MTBE by ozone and peroxone processes

Abstract

These two processes effectively remove MTBE but may also increase bromate.Initial pilot‐scale investigations demonstrated that both ozone alone and a combination of ozone and hydrogen peroxide (known as peroxone) can remove methyl tertiary butyl ether (MTBE) from water sources used by the Metropolitan Water District of Southern California. Under the tested conditions, peroxone more effectively removed MTBE than did ozone alone. In pilot tests, peroxone (here, 4 mg/L ozone and 1.3 mg/L hydrogen peroxide) removed an average of about 78 percent of the MTBE from water samples taken from the California State Water Project and the Colorado River. However, in peroxone‐treated samples from both water sources at ambient conditions, bromate was produced at concentrations above the maximum contaminant level of 10 μg/L for bromate in drinking water. A lower pH of 6.5 reduced bromate formation by about 20 percent in samples from both water sources, but it did not reduce the bromate concentration below 10 μg/L (the water sources contained about 0.1 mg/L bromide). Further optimization of the peroxone process may minimize bromate formation while providing acceptable MTBE removal and disinfection.