Patent ID: 7282151

Claim:
A process comprising: (a) subjecting an oxidizer purge stream comprising a carboxylic acid, a metal catalyst, impurities, water and a solvent to evaporation in a first evaporator zone to produce a vapor stream and a concentrated purge slurry; wherein said oxidizer purge stream is a purge of an oxidizer mother liquor that is recycled to an oxidation zone; (b) subjecting said concentrated purge slurry in a second evaporator zone to form a solvent rich stream and a super concentrated purge slurry; (c) filtering a super concentrated purge slurry in a solid-liquid separation zone to form a filter cake and a mother liquor; (d) washing said filter cake with a wash feed in said solid-liquid separation zone to form a washed cake and a wash filtrate; and optionally dewatering said wash filtrate in said solid-liquid separation zone to form a dewatered cake; wherein said solid-liquid separation zone comprises at least one pressure filtration device; wherein said pressure filtration device is a rotary pressure drum filter; and wherein said rotary pressure drum filter is operated at a pressure of about 1 atmosphere to about 5 atmospheres; (e) mixing in a mixing zone water and optionally an extraction solvent with said mother liquor and all or a portion of the said wash filtrate to form an aqueous mixture; (f) contacting an extraction solvent with said aqueous mixture in an extraction zone to form an extract stream and a raffinate stream; and (g) separating said extract stream in a separation zone to form a high boiling point organic impurities stream and a recovered extraction solvent stream.