Methods and systems for recovering sulfur dioxide from a Claus unit process emissions stream are provided. The method comprises the steps of generating a process emissions stream from a thermal oxidizer or other combustion device, introducing the emissions stream to an SO2 removal system, introducing the SO2 rich stream from the SO2 removal system to a CO2 removal system, and introducing an enriched SO2 stream back to the Claus unit. The SO2 removal system can include one or more SO2 selective membranes. The CO2 removal system can include one or more CO2 selective membranes.