Catalytic destruction vs. adsorption in controlling dioxin emission

This study investigates the removal efficiencies of PCDD/Fs achieved with a catalytic filter (CF) and with activated carbon injection followed by bag filter (ACI+BF) as applied in an industrial waste incinerator (IWI) and a hazardous waste incinerator (HWI), respectively. Catalytic filtration has been successfully applied to remove PCDD/Fs from gas streams. Comparing the CF to the ACI+BF system, it appears that the PCDD/F removal efficiency achieved with a CF is higher than that of an ACI+BF system. The PCDD/F emissions from both incinerators are well controlled to meet the regulatory limit of 0.1 ng I-TEQ/Nm(3). Additionally, the PCDD/F concentration in BF ash is higher than the regulation limit of Taiwan (1.0 ng I-TEQ/g). In contrast, the PCDD/F concentration in CF ash is only 0.274 ng I-TEQ/g. The difference is attributed to the fact that the ACI+BF system just transfers PCDD/Fs from gas phase to solid phase and further increases the PCDD/F concentration in fly ash, while CF technology effectively destroys the gas-phase PCDD/Fs. Therefore, the disposal of the fly ash discharged from CF would be less expensive compared with the fly ash discharged from the ACI+BF system. In this study, the PCDD/F emission factors of both incinerators are also established.