Preliminary study on biodegradation and detoxification of dioxins

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For the purpose of the remediation of the dioxin-polluted soil, biodegradations using white-rot fungi, chemical decompositions, and detoxification were investigated. The results were summarized as follows :Biodegradation : The decomposition activity of several white-rot fungi was examined using low-toxic 2, 7-DCDD (dichloride). As the resutl, there was the decompostion of 30-40% dioxin in the culture (oxygen 100%, lignin addition 20mg/10ml) for 2 weeks in Lentinus edodes, Grifola frondosa, and Flammulina velutipes. These activities were almost equivalent to that of a white-rot fungus, Phanerochaete chrysosporium (noxious and the decomposition activity has already been proven). The familiar mushrooms were found to have the dioxin decomposition activity, indicating the possibility of the remediation plant using hte mushrooms in the futureChemical decomposition : The screening of pinment decomposition activity was carried out for various reagents. As the result, Fe^<3+>-h_2O_2 mixed reagent had a strong activity for DCDD. Under the condition of 70℃, Fe^<3+> (8mM) - H_2O_2(1%), DCDD was almost perfectly decomposed for 15 min. Also, this mixed reagent was effective for DCDD decomposition in hte model soil. This chemical decomposition method is greatly expected as a practical remediation method because of its cost performance and no secondary contamination ot the environmentDetoxification : We found that DCDD in the soil could perfectly remove by a steam distillation, and it was effective even in an actual polluted soil