Disclosed is an optimized process for more efficiently and economically carrying out the liquid-phase oxidation of an oxidizable compound. Such liquid-phase oxidation is carried out in a bubble column reactor that provides for a highly efficient reaction at relatively low temperatures. When the oxidized compound is para-xylene and the product from the oxidation reaction is crude terephthali c acid (CTA), such CTA product can be purified and separated by more economic altechniques than could be employed if the CTA were formed by a conventional high- temperature oxidation process.