TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The absorbent in the first absorber comprises propylene carbonate.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The adsorbent in the dehumidifying absorbers comprises silica gel.    TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Apparatus (Claimed): Apparatus comprises gas wells providing a source of landfill methane gas; collector connected to the gas wells; first separator connected to the collector, and capable of separating any heavier liquids and solids in the landfill methane gas flowing into the first separator; compressor unit connected to the collector that compresses the gas exiting the first separator; first absorber connected to the compressor unit in which an absorbent and the landfill methane gas are mixed to produce a carbon dioxide saturated absorbent and methane gas from which most of the carbon dioxide has been extracted; second separator connected to the first absorber in which much of the carbon dioxide and methane is separated from the carbon dioxide saturated absorbent; first dehumidifying absorber connected to the first absorber, the second separator, and the first separator; second dehumidifying absorber connected to the first absorber, the second separator, and the first separator; adsorbent contained within the first and second absorbers; gas dehumidification configuration in which the adsorbent strips water from the purified methane gas exiting the first absorber; regeneration configuration in which gas from the second separator strips water from the adsorbent in the first or second dehumidifying absorbers before conducting the gas from the second separator to the first separator; mechanism for switching the first and second absorbers from the gas dehumidification configuration to the regeneration configuration; and desorber apparatus connected to the second separator and the first absorber that removes most of the carbon dioxide from the saturated absorbent to the first absorber.Preferred Method: The opening and closing electric valves (37a) switches between regeneration of the adsorbent and dehumidification of the purified methane gas. The switching to dehumidifying the purified methane gas further comprises opening an electric valve to connect the first absorber and the dehumidifying absorber; closing an electric valve to separate the second separator (S2) from the dehumidifying absorber; and closing an electric valve to separate the dehumidifying absorber from the first separator. The carbon dioxide saturated absorbent is regenerated by degassing the carbon dioxide saturated absorbent in a desorber connected to the second separator to produce regenerated absorbent and carbon dioxide gas; maintaining a vacuum in the desorber to cause a deeper regeneration of the carbon dioxide saturated absorbent to take place; conducting the regenerated absorbent to a tank connected to the desorber; compressing the regenerated absorbent with a suction pump; smoothing the pulsation of the regenerated absorbent with a liquid depressurizer connected to the suction pump; conducting the regenerated absorbent to the first absorber.