INFLUENCE OF HCL ON THERMAL-DECOMPOSITION OF PCDDS PCDFS IN FLY-ASH FROM MSW INCINERATOR/

Fly ash from an electrostatic precipitator in a MSW incinerator was he ated at 573-773K for 2-60 minutes in various test gases (nitrogen, air or simulated flue gas (O-2 10%, N-2 82%, CO2 8%)) with or without 500 or 1000ppm HCl and 20% H2O. Thermal decomposition behavior of PCDDs/P CDFs in fly ash was studied. In any test gas, PCDDs/PCDFs decomposed r apidly at over 673K regardless of HCl presence. Detoxification of PCDD s/PCDFs was more inhibited in simulated flue gas with 1000ppm HCl than in nitrogen or air but concentration of PCCDs/PCDFs decreased to less than 0.01ng-TEQ/g at 773K. Furthermore, it was demonstrated than diox ins in fly ash decomposed almost completely at the bottom of boiler se ction in a MSW incinerator.