A method of scrubbing flue gas includes introducing flue gas comprising an acidic gas through an inlet into a tower; spraying an acid-absorptive fluid into the tower such that the acid-absorptive fluid contacts the flue gas; accumulating the acid-absorptive fluid in a recycle tank portion of the tower; and introducing an oxygen-containing gas into the acid-absorptive fluid in the recycle tank portion of the tower, wherein the oxygen-containing gas is introduced through at least one opening of an aerator, each of the at least one openings are positioned to release the oxygen-containing gas at least at a distance greater than or equal to a predetermined radial distance from the flue gas inlet, the predetermined radial distance being equal to at least 10% of a diameter of the recycle tank portion of the tower.