| OCR Text |
Show However, the mutagenicity of particulates and PUF extracts caused significantly higher potence of revertants to S. Typhimurium TA98 in the presence of S9 mixture than that without S9 additive. This indicates that the emitted gas from the PS incineration contain not only direct-acting mutagens but also indirect mutagens, which are usually activated by the mixed-function oxygenases in the microsomes of animal liver to become ultimate mutagens whether the PS incineration system added metallic chloride or not. The mechanism of epoxide formed and nucleophilic epoxid opening could be involved by metabolic oxidation. In the body, the epoxide ring should react with an amino group in celluar D N A to give an altered D N A that is covalently bound to the PAH. With ts D N A thus altered, the cell was unable to reproduce normally. CONCLUSION The critical temperature in the second-stage incinerator for the maximum yield of 14 PAHs was shifted from 1000 °C to 900 °C when metallic chloride (BaCh or NaCl) was added into the incineration system. Log(K) values, the ratios between the PAHs in gas phase and the PAHs in solid phases( per particulates weight; 1/mg), increased as the stage-two pyrolysis temperature increased. When the stage-two incineration system was controlled at 900 °C and various oxygen supplies, the maximum value of log(K) occured at 00525 02-Nl/min. Concerning the mutagenicity in the air emissions, the maximum mutagenicity of particulates and PUF extracts occurred at 1100 °C, when the pyrolysis temperature was increased from 700 to 1200 °C. The mutagenicity of PUF extracts was weaker than the mutagenicity of particulates extracts. When oxygen supply was increased to 0.210 Nl/min and stage-two temperature was controlled at 900 °C, the mutagenicity of particules and PUF extracts were till higher for NaCl additive and were much higher for BaCh additive. Moreover, the mutagenicity is much higher in presence of rat liver microsomal fraction (S9 mixture) than that without S9 additive. Finally, from the results of this stuy, the metallic chloride in the municipal solid waste (MSW) should be considered as an important factor in -6- |
