Patent ID: 8382961

Claim:
A process for recovering acetic acid, azeotropic agent, re-usable water and other reaction products such as p-toluic acid, from aqueous streams generated during terephthalic acid production, in which there is no requirement for make up water for the process and the amount of wastewater discharged is minimized; the process comprising: (a) providing an apparatus, comprising an azeotropic distillation column; a decanter; an azeotropic agent stripper; a pair of mother liquor extraction columns sequentially connected in series; and a solvent stripper; (b) feeding to the azeotropic distillation column, a liquid acetic acid containing input stream containing organics and water, and optionally a acetic acid-containing vapor stream; (c) recovering acetic acid as bottoms stream from the azeotropic distillation column; (d) condensation of a tops volatiles stream from the azeotropic distillation column and separation in the decanter into an aqueous phase and an organics stream that is rich in azeotropic agent; (e) splitting the organics stream from the decanter into a stream which is returned to the azeotropic distillation column and a stream which is fed to the second of the pair of mother liquor extraction columns; (f) sending the water phase from the decanter to the azeotropic agent stripper for further recovery of the azeotropic agent; (g) feeding to the first of the pair of mother liquor extraction columns, a p-toluic acid containing mother liquor stream and a solvent stream e.g. of substantially pure p-xylene, to form an organics extract stream containing primarily the solvent e.g. p-xylene with extracted p-toluic acid, and sending the recovered organics stream to an oxidation reactor for re-use in the terephthalic acid purification process; (h) feeding to the second of the pair of mother liquor extraction columns, the water stream from the first of the pair of mother liquor extraction columns and the azeotropic rich organics stream; (i) returning the recovered organics stream from the second of the pair of mother liquor extraction columns to the azeotropic distillation column; (j) sending the recovered aqueous stream from the second of the pair of mother liquor extraction columns to the solvent stripper for recovery of azeotropic agent as tops stream which is sent to the decanter while substantially pure water stream from bottom of the solvent stripper is re-cycled to the terephthalic production process for re-use; and (k) recovering a water stream from the azeotropic agent stripper for re-use in the terephthalic acid purification process.