Removal of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans in Flue Gases by Venturi Scrubber and Bag Filter

Abstract

This study investigates the individual removal efficiencies of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) by venutri scrubber and bag filter, which operated in one medical waste incinerator (MWI) and one secondary aluminum smelter (secondary ALS), respectively. Stack flue gases, effluent, and fly ash were measured for PCDD/Fs to characterize the performance of the venutri scrubber and the bag filter for reducing PCDD/F emission. The mean PCDD/F concentrations in the stack flue gases of the MWI and secondary ALS were 0.511 and 10.6 ng I-TEQ Nm^(-3) (calculated according to International Toxic Equivalency Factors [I-TEQ] and normalized to dry flue gas conditions of 273 K and 11% O2), while concentrations in the effluent, including ash and wastewater from the venture scrubber and fly ash from the bag filter, were 7.51 ng I-TEQ g^(-1), 154 pg I-TEQ L^(-1), and 5.59 ng I-TEQ g^(-1), respectively. The average removal efficiencies of tetra-, penta-, hexa-, hepta-, and octa-PCDD/Fs by bag filter are 8.2%, 10.6%, 33.5%, 52.4%,and 59.1%, respectively. This suggests that highly chlorinated PCDD/Fs with lower vapor pressures are more easily adsorbed onto the particulate and consequently more easily removed by bag filter. The removal efficiencies of the bag filter on the total PCDD/F emission and the total PCDD/F I-TEQ emission are 37.6% and 11.2%, respectively, while whose of the venture scrubber are 46.0% and 44.5%, respectively. Although the operating conditions of the venutri scrubber and the bag filter are different, the removal efficiencies of each for PCDD/Fs is inadequate.