Abstract: Disclosed embodiments concern adsorptive gas bulk separation systems and methods that may be advantageously less expensive to utilize than some in the prior art. Embodiments of the present invention concern processing a feed gas source, typically comprising at least one fuel gas component and at least one diluent, using a displacement purge adsorptive separator apparatus comprising at least one adsorbent bed, at least one purge gas source for purge regeneration of the at least one adsorbent bed, and a product conduit for supplying upgraded gas product. The feed gas typically is supplied to the displacement purge adsorptive separator apparatus at substantially the ambient pressure of the feed gas source. The displacement purge adsorptive separator apparatus is operable to adsorb at least a portion of the at least one diluent component from the feed gas stream to produce an upgraded gas.