Evaluating an AOP for TCE and PCE removal

The authors evaluate an AOP by introducing elevated TCE and PCE into groundwater and propose a chemical kinetic model for evaluating AOP performance. A full‐scale evaluation of an advanced oxidation process (AOP) involving the use of ozone (O 3 ) and hydrogen peroxide (H 2 O 2 ) at a 126‐L/s (2,000‐gpm) flow rate was completed in a plug‐flow hydraulic regime by the Los Angeles (Calif.) Department of Water and Power. This facility is the first full‐scale AOP for trichloroethylene (TCE) and tetrachloroethylene (PCE) treatment in the United States, if not the world. The purpose of this study was to challenge the performance of the plant with typical groundwater pollutants, propose a kinetic model for the process, and confirm past laboratory and pilot studies. Groundwater containing up to 447 μg/L TCE and 163 μg/L PCE was treated to below the maximum contaminant (MCL) level of 5 μg/L. The optimum H 2 O 2 /O 3 dose ratio was 0.5–0.6. Removal efficiency of TCE and PCE declined as groundwater alkalinity increased. Investigation of by‐product formation showed formation of assimilable organic carbon and bromate following the treatment process. A kinetic model calibrated using the experimental data predicted the concentration of TCE and PCE in the finished water reasonably well.