In order to reduce incoming atmospheric carbon dioxide levels in compressed air prior to cryogenic distillation, a water spray cooling tower equipped with biocatalytic packing, or fed with absorptive reagents, is used to convert gaseous carbon dioxide into bicarbonate ions which dissolve in the cooling water. The hydration reaction and refrigeration occur synergistically. The bicarbonate ions are subsequently removed from the solution using the heat from the compressed air in a regenerator re-boiler unit, and then fed to a percolation cooling tower for releasing CO.sub.2 and cooling.