Disclosed is an optimized process and apparatus for more efficiently producing aromatic dicarboxylic acids (e.g., terephthalic acid). In one embodiment the process/apparatus reduces costs by recovering and purifying residual terephthalic acid present in the liquid phase of an initial oxidation slurry. In another embodiment the process apparatus reduces costs associated with hydrogenation by forming a final composite product containing unhydrogenated acid particles.