EPA/540/R-94/531

This report presents the results of bench-scale testing on degradation of 2,3,7,8-TCDD using W photolysis, and PCB degradation using UV photolysis, chemical oxidation and biological treatment. Bench-scale tests were conducted to investigate the feasibility of a two-phase detoxification process that would have application to the treatment of soils contaminated with polychlorinated biphenyls (PCBs) and 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD). The first step in the process was to degrade the contaminants by using ultraviolet (UV) radiation facilitated by the addition of a surfactant to mobilize the contaminants. As an alternative, an advanced oxidation process using iron (Fe) catalyzed hydrogen peroxide (Fenton's Reagent) was also tested. Biological degradation, the second step, was then used to further degrade organic contaminants and detoxify the soil. UV photolysis tests were conducted independently using a medium pressure mercury (Hg) lamp, and sunlight. a 10 hertz (Hz) pulsed Hg lamp Results from UV testing on a TCDD soil (200-300 parts per billion) indicated that there was no apparent destruction of the dioxin on the soil. Surface soil contaminated with about 10,000 parts per million (ppm) PCBs and a pit soil containing about 200 ppm PCBs were tested under similar conditions. The PCB reductions spanned the range up to a maximum of 69 percent. Batch experiments using the Fenton's Reagent alternative to degrade PCBs gave similar results with reaction times of over 100 hours.

Biological treatment on surfactant/UV-treated and untreated soil was evaluated in two bioslurry treatment experiments. The bioslurry experiments evaluated PCB degradation on surfactant/UVtreated and untreated soils using cultures, with and without PCB degradation inducer chemical addition. The inducers used were biphenyl and 4-bromobiphenyl. Bioslurry treatment did not provide significantly different results for the UV-treated surface soil versus the untreated soil. Percent reductions of PCBs were highest for an untreated soil containing 350 ppm PCBs which gave 70, 20 and 30 percent reduction of the di, tri and tetra-PCBs, respectively. using inducers, In the enhanced bioslurry experiment the addition of 1,000 ppm biphenyl stimulated greater reduction in PCB concentrations on the same soil.

This report is submitted in fulfillment of cooperative agreement number CR816817-02-0 by IT Corporation under partial sponsorship of the USEPA. This report covers the period from September 1990 to July 1993, with the completion of work in July 1993.