TREATMENT OF VOC-CONTAMINATED GROUNDWATER BY HYDROGEN-PEROXIDE AND OZONE OXIDATION

Groundwater contamination by volatile organic compounds (VOCs) has been the subject of numerous Superfund Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) investigations. When VOCs were detected in groundwater of the San Gabriel Basin, the valley was listed as a Superfund site. As part of the remedial investigation (RI), treatment techniques were investigated to determine possible procedures for reducing the VOCs in these waters to drinking water standards. Bench-scale studies were conducted to assess the applicability of the ozone/hydrogen peroxide oxidation process for treatment of PCE, TCE, CTC, and DCE. Results of the treatability study indicated the following: (1) an H2O2/O3 molar ratio of 0.5 yielded higher VOC oxidation rates and the most efficient use of oxidants compared to other ratios; (2) the higher ozone mass feed rate of the two ground-water sources tested yielded higher oxidation rates; (3) reaction rate constants were essentially independent of VOC concentrations; (4) gas stripping was small or negligible for DCE, TCE, and PCE, whereas CTC was removed primarily by stripping; and (5) first-order rate constants for the "best" oxidant conditions tested were 15-25 x 10(-4) sec-1 for PCE, 30-60 x 10(-4) sec-1 for TCE, and > 90 x 10(-4) sec-1 for DCE.