Abstract: By-product or waste streams from adipic acid plants which contain adipic acid, glutaric acid, succinic acid, nitric acid and catalyst values of copper and vanadium are treated to substantially recover all the components thereof by esterifying the dibasic acids with an alcohol, such as normal butanol, which creates esters that are substantially immiscible in the aqueous solution, allowing the organic esters to form a separate layer from the aqueous phase in which the metal values are retained, recovering the organic layer containing the esterified dibasic acids and thereafter re-using the aqueous solution containing the catalyst values in the adipic acid process.