NOVELTY - Recovering volatile carboxylic acid from an aqueous stream, comprises: (a) steam stripping the carboxylic acid from the aqueous stream, where the steam stripping comprises contacting the aqueous stream with steam by flowing aqueous stream and steam countercurrent to one another to produce vapor stream comprising vaporized carboxylic acid and steam, and a stripped aqueous stream; (b) extracting the vaporized carboxylic acid with an organic solvent; (c) returning the steam from step (b) to the steam stripping step (a); and (d) separating the carboxylic acid from the organic solvent.    USE - The process is useful: to recover volatile carboxylic acid, preferably acetic acid (claimed); and in industrial process streams containing carboxylic acids, including those containing lignin and high molecular weight compounds.    ADVANTAGE - The process: allows for the reuse of organic solvent obtained from the separating step; is simple and cost-effective; and does not require a subsequent acidification step to recover carboxylic acid.    DETAILED DESCRIPTION - Recovering volatile carboxylic acid from an aqueous stream, comprises: (a) steam stripping the carboxylic acid from the aqueous stream, which is produced by a conversion process using a lignocellulosic feedstock as a substrate, where the steam stripping comprises contacting the aqueous stream with steam by flowing the aqueous stream and the steam countercurrent to one another, thus producing a vapor stream comprising vaporized carboxylic acid and steam and a stripped aqueous stream; (b) extracting the vaporized carboxylic acid with an organic solvent by contacting the vapor stream with the organic solvent to produce (b1) a stream comprising the organic solvent and the carboxylic acid and (b2) the steam at least substantially depleted of the carboxylic acid, where the organic solvent has an atmospheric boiling point of at least 150 degrees C and is insoluble in water; (c) returning the steam from step (b) to the steam stripping step (a) to further strip the carboxylic acid from the aqueous stream; and (d) separating the carboxylic acid from the organic solvent. An INDEPENDENT CLAIM is also included for recovering volatile carboxylic acid from the aqueous stream, comprising: (e) steam stripping the carboxylic acid from the aqueous stream, where the aqueous stream is produced by a conversion process comprising pretreating a lignocellulosic feedstock with acid/alkali to produce a pretreated feedstock composition comprising fiber solids containing cellulose, hydrolyzing the cellulose to glucose with cellulase enzymes and beta -glucosidase, and fermenting the glucose to ethanol (preferred) or butanol; and performing steps (b)-(d) as per se above.    DESCRIPTION OF DRAWING(S) - The figure shows a flow diagram of the process for recovering volatile carboxylic acid from an aqueous stream.    Aqueous feed stream (10)    Second stripping stage (25)    Aqueous stream (40)    First stripping stage (50)    Vapor stream (110)