A contaminant gas is removed from a feed gas in two absorption and stripping circuits operated in tandem. The gas is first passed through a rich gas absorber producing a rich absorption liquor from which contaminant gas is stripped in a rich liquor stripper. A lean gas exiting the rich gas absorber is passed through a lean gas absorber, producing a lean absorption liquor from which contaminant gas is stripper in a lean liquor stripper. Regenerated absorption media exiting the respective strippers are recirculated to the respective absorbers.