Abstract: A method and apparatus for separating undesirable components from a waste gas by adsorption of the components onto a granular adsorbent. The gas is caused to flow serially through two distinct side-by-side layers of adsorbent both moving parallel to one another in a direction perpendicular to the direction of gas flow. The adsorbent material is so controlled that the particles of the second layer to be contacted by the gas are less loaded with impurities than the particles of the first layer. In one embodiment, this result is achieved by moving the second layer faster than the first layer.