Characteristics of PCDD/Fs during the melting process of municipal solid waste incinerator fly ash were investigated by lab-scale experiments. Two kinds of fly ash samples

obtained from fixed-bed and fluidized-bed incinerators respectively

were used. The experiments were performed at various temperatures

two kinds of atmosphere (O2 and N2) and different residence times

and the DRE(decomposition and removal efficiency) of PCDD/Fs contained in fly ash was studied. The result revealed that approximately 99.96% dioxins were decomposed by melting under experimental condition

and the concentration of dioxins in exhaust gas of melting furnace was below the detection limit. There was an increase in temperature from 1100℃ to 1460℃ resulting in an increase of DRE of dioxins in fly ash from 99.968% to 100% in an oxidative melting atmosphere. The DRE of dioxins in the oxidative atmosphere is higher than that in inert atmosphere. The results will be helpful not only to studying the mechanism of dioxin decomposition in the melting process but also to evaluating the effect of pollution control.