Removal of PCDD/Fs and CBzs by different Air Pollution Control Devices in MSWIs

This study investigated the removal efficiencies of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and chlorobenzenes (CBzs) by different air pollution control devices (APCDs) in three municipal solid waste incinerators (MSWIs). These devices were the semi-dry flue gas desulfurization (SDFGD) system, activated carbon (AC) injector, bag filters (BF), selective catalytic reduction (SCR) reactor, and wet scrubber. The SDFGD system, AC injector, and BF exhibited similar removal efficiencies for all of the pollutants. Overall, the removal efficiency of CBzs was also considerably lower than the PCDD/Fs. The less chlorinated CBzs were also less likely to be adsorbed by AC and BF and more likely to be decomposed by the SCR reactor. Additionally, the memory effect in the wet scrubbers elevated the concentrations of the PCDD/Fs and even the CBzs in the flue gas, with the highest increases observed for penta- to hepta-chlorinated PCDD/Fs and TrCBzs. Given the different effects of these various devices, especially the wet scrubber, the correlation between PCDD/F and CBz removal should be individually assessed for each APCD unit. More accurate indicators of PCDD/F removal are also examined.