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Abstract

Ammonia is recovered from waste water containing NH.sub.3, at least one acid gas (CO.sub.2, H.sub.2 S) and inert gases. Firstly, the waste water is passed through a pretreatment column and then, at least in part, into a total stripping column. The top product from the total stripping column is cooled in a condenser, and an aqueous NH.sub.3 -containing condensate coming from the condenser is fed to an NH.sub.3 stripping column. The top product from the NH.sub.3 stripping column is brought into direct contact with circulating aqueous NH.sub.3 -containing condensate in a wash column, and NH.sub.3 is recovered from the top product from the wash column. Some of the bottom product from the wash column is fed back into the NH.sub.3 stripping column. The temperature in the bottom region of the pretreatment column is set to from less than 30 to 200.degree. C., a sub-stream of the waste water is introduced into the upper region of the pretreatment column, and a second sub-stream of the waste water is fed into the pretreatment column below the first sub-stream. At least 80% of the NH.sub.3 introduced from the total stripping column is condensed in the condenser. A waste-water stream is taken off from the total stripping column, at least part thereof is cooled to temperatures of from 10 to 60.degree. C., and the cooled waste-water stream is passed into the top region of the pretreatment column.

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