Innovative treatment of soil contamination: radiolytic destruction of dioxin and co-contaminants by cobalt-60

Recent work in our laboratory has demonstrated that gamma radiolysis is a feasible method by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can be converted to products of negligible toxicity. A standard soil has been artificially contaminated to a level of 100 ppb TCDD and destruction to a level less than 1 ppb has been achieved at a radiation dose of 800 KGy and with the addition of certain soil amendments (water and surfactant). By-product analysis has illustrated that the destruction occurs via step-wise reductive dechlorination and mass balance on carbon has been demonstrated. The presence of co-contaminants at much higher levels does not interfer with TCDD destruction. These results in combination with scavenger studies and target theory calculations indicate that direct radiation effects account for the major route of destruction. Process efficiency has been verified using real contaminated soils and sediments. A reactor design is proposed and an economic analysis is presented to show that radiolysis is technically feasible and economically competitive.