While dealing with lean acid gases with undesired contaminants such as ammonia, BTEX and cyanides, Fluor's patented acid gas enrichment processes significantly reduce the energy consumption and equipment count while enhancing the sulfur removal efficiency when compared to conventional processes. More importantly, these technologies effectively produce an ultra lean amine to meet the most stringent environmental requirements while simultaneously achieving the necessary enrichment to maintain a stable flame in the sulfur plant reaction furnace for complete destruction of contaminants. The integrated processes can be used to cost effectively integrate acid gas removal, acid gas enrichment and Claus tail gas treating processes to achieve an overall sulfur recovery up to 99.99%. The process rejects CO₂ and BTEX while absorbing H₂S with enhanced solvent regeneration via the patented Double Absorption Process (DAP) and Selective Treating Regeneration Enhancement Process (STREP). The configurations are suitable for processing lean acid gases with H₂S concentration below 10% and can result in about 25% energy savings with less equipment requirements.