Treatment of Aqueous Liquids and the Preparation of Anthranilic Acid

A continuous process for forming an anthranilic acid which includes treating in a first step a mixture comprising a carbonate salt and an anthranilic acid salt of the formula (I) where R is selected from hydrogen and one or more substituted or unsubstituted hydrocarbon groups, and M is a univalent cation, with an inorganic acid in an aqueous medium to form an aqueous slurry comprising anthranilic acid and inorganic salts. The slurry is filtered to provide a residue comprising part of said anthranilic acid and a filtrate comprising the remainder of said anthranilic acid and said inorganic salts. Further anthranilic acid is extracted from said filtrate with a water-immiscible organic solvent, whereby the further anthranilic acid is separated into an organic phase while the inorganic salts remain in an aqueous phase. The organic phase is contacted with an aqueous alkali to thereby transfer said further anthranilic acid from said organic phase to an aqueous phase as an anthranilic acid salt. The transferred anthranilic acid salt is added to the mixture of the first step. Also disclosed is a process for the treatment of waste water containing organic material and greater than 10 g/l inorganic salts. The waste water is contacted with a volatile water-immiscible organic solvent. An organic phase is separated from an aqueous phase containing less than 0.5 g/l organic material. The organic solvent from the organic phase is evaporated to leave a residue which is incinerated.