Treatment of effluent gases

A method is described for recovering a noble gas, such as xenon or krypton, from a first gas mixture comprising a plurality of components, one of which is the noble gas and the others are typically helium and/or nitrogen, argon, and relatively light fluorocarbons. The gas mixture is first conveyed to a gas chromatography column for separating the noble gas from the other components of the gas mixture. As the noble gas travels relatively slowly through the column, the other components are exhaust from the column before the relatively slow noble gas. Following the exhaust of these other components, a purge gas is supplied to the column to flush the noble gas therefrom. A second gas mixture comprising the noble gas and the purge gas is conveyed from the column to a membrane separator to separate the second gas mixture into a noble gas-rich gas stream and a purge gas-rich gas stream, which may be recirculated back to the column for re-use.