Remediation for groundwater, soil, sediment bodies, bodies of water, tanks, pipes, and their surrounding areas are described. Remediation includes treating a site contaminated with toxic organic compounds by assessing for the presence or absence of suitable ozonphilic bacteria at the site and introducing ozone to the site. The ozonphilic bacteria are introduced to the site if the ozonphilic bacteria are not present or not present in sufficient quantities in the site. Ozone is introduced to the site in an amount sufficient to stimulate growth of the suitable ozonphilic bacteria. Other oxidants can also be used.