A process comprising: (a) producing a residue stream from manufacture of an aromatic polycarboxylic acid by liquid phase oxidation of the corresponding aromatic precursor, wherein the aromatic polycarboxylic acid comprises at least one member selected from the group consisting of terephthalic acid, isophthalic acid, orthophthalic acid, trimellitic acid, naphthalene dicarboxylic acid and mixtures thereof; (b) separating the residue stream into a dicarboxylic acid rich stream, a catalyst and tricarboxylic acid rich stream, and a monocarboxylic acid rich stream, wherein the separation comprises simultaneous extraction of the residues stream with two liquid phases, followed by filtration; wherein the monocarboxylic acid comprises at least one member selected from the group consisting of benzoic acid, paratoluic acid and its isomers, and mixtures thereof, wherein the dicarboxylic acid comprises at least one member selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and mixtures thereof, wherein the tricarboxylic acid comprises at least one member selected from the group consisting of trimellitic acid, hemi-mellitic acid, trimesic acid and mixtures thereof, wherein the catalyst comprises at least one member selected from the group consisting of a cobalt salt, a manganese salt, hydrobromic acid, vanadium, chromium, iron, molybdenum, nickel, cerium, zirconium, hafnium and mixtures thereof, wherein the hydrobromic acid can be present as the sodium salt, and wherein the simultaneous two phase extraction of residues involves the use of water and an organic solvent comprising at least one member selected from the group consisting of toluene, benzene, cyclohexane, petroleum ether and mixtures thereof; and (c) separating at least one aromatic polycarboxylic acid from the dicarboxylic acid rich stream. (a) producing a residue stream from manufacture of an aromatic polycarboxylic acid by liquid phase oxidation of the corresponding aromatic precursor, wherein the aromatic polycarboxylic acid comprises at least one member selected from the group consisting of terephthalic acid, isophthalic acid, orthophthalic acid, trimellitic acid, naphthalene dicarboxylic acid and mixtures thereof; (b) separating the residue stream into a dicarboxylic acid rich stream, a catalyst and tricarboxylic acid rich stream, and a monocarboxylic acid rich stream, wherein the separation comprises simultaneous extraction of the residues stream with two liquid phases, followed by filtration; wherein the monocarboxylic acid comprises at least one member selected from the group consisting of benzoic acid, paratoluic acid and its isomers, and mixtures thereof, wherein the dicarboxylic acid comprises at least one member selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and mixtures thereof, wherein the tricarboxylic acid comprises at least one member selected from the group consisting of trimellitic acid, hemi-mellitic acid, trimesic acid and mixtures thereof, wherein the catalyst comprises at least one member selected from the group consisting of a cobalt salt, a manganese salt, hydrobromic acid, vanadium, chromium, iron, molybdenum, nickel, cerium, zirconium, hafnium and mixtures thereof, wherein the hydrobromic acid can be present as the sodium salt, and wherein the simultaneous two phase extraction of residues involves the use of water and an organic solvent comprising at least one member selected from the group consisting of toluene, benzene, cyclohexane, petroleum ether and mixtures thereof; and (c) separating at least one aromatic polycarboxylic acid from the dicarboxylic acid rich stream.