Abstract: In order to recover an organic solvent from an airstream blown through one or more treatment units such as dry-cleaning machines, two adsorbers filled with activated charcoal are alternately connected between an incoming duct and an outgoing duct in series with a blower, a normally inactive air heater upstream of the adsorbers and a normally inactive air dryer downstream of the adsorbers. A programmer periodically reverses two switchover valves for passing the airstream through one or the other adsorber in respective half-cycles during which steam is blown through the inactive adsorber for regenerating its active mass. If no treatment unit requires solvent removal, the continuously circulating airstream is returned from the dryer outlet to the heater inlet through an otherwise closed bypass controlled by a valve in response to changes in duct pressure or to a switching signal from a treatment unit.