Abstract: The present invention provides a system and process for the automatic conditioning of biogas to remove a wide range of contaminants including, for example, moisture, hydrogen sulfide, mercaptans, and NMOCs all in a single step. The biogas is passed through one or more vessels containing at least three different types of physical adsorbents. Contaminants in the biogas are removed from the biogas via physical adsorption onto the surfaces of the various media. Multiple media types are used in each vessel as different contaminants adsorb more or less onto various adsorbent media. The final proportions and types of media used are based on each particular biogas range of contaminants. Multiple vessels are used such that one or more vessels are always on-line and conditioning biogas, while one or more vessels is always off-line and either being reactivated or in standby service mode.