In this process, a system of compression and distillation columns drastically reduces the temperature of the gas mixture to a point where methane is liquified and the nitrogen is not.
For smaller volumes of gas, a system utilizing pressure swing adsorption (PSA) is a more typical method of separation.
This means nitrogen is able to diffuse through the adsorbent, filling adsorption sites, whilst methane is not.
PSA is a flexible method for nitrogen rejection, being applied to both small and large flow rates.
Depending on the vendor, high degrees of pretreatment of the gas stream (removal of water vapor and heavy hydrocarbons) may be necessary for the system to operate optimally and without damage to the adsorbent material.