Methods of processing the atmosphere.
Collection of atmosphere
A device similar to a vacuum pump collects Martian air. The gas is compressed to be able to liquefy carbon dioxide.
The atmosphere is cooled to remove water vapor as a condensate. As the gas continues to cool most of the rest of the water vapor is removed as frost. The dry gas is cooled further to remove carbon dioxide condensate. There will be more carbon dioxide than is needed for industrial purposes so some of it will be expanded to help power the compressors and to cool the incoming gas. Then excess CO2 will be discharged.
Buffer gas for breathing
The balance of the collected gas contains mostly nitrogen and argon which can be used as mixed as a buffer for oxygen to produce a breathable atmosphere. Carbon monoxide can be catalytically removed.