Metallgesellschaft Aktiengesellschaft

Chemie Linz Aktiengesellschaft

Hans M Stonner

Paul Wiesner

Alfred Schmidt

Gert Ungar

Fritz Wohler

Alfred Garber

Wolfgang Hilsebein

An aqueous effluent is supplied to a stripping column (total stripping column) from which a mixture that is rich in NH.sub.3, CO.sub.2 and H.sub.2 S is withdrawn as a head product. In at least one additional stripping column the mixture is separated into a mixture which is rich in NH.sub.3 and a mixture which is rich in the sour gaes CO.sub.2 and H.sub.2 S. The mixture which is rich in NH.sub.3 is scrubbed with liquid ammonia. The overhead product from the total stripping column is cooled in a condenser under a pressure of 1 to 7 bars and is thus transformed into a liquid phase to such an extent that the liquid phase contains 70 to 100% of the NH.sub.3 which has been supplied to the condenser. The liquid phase is supplied at a temperature of 30.degree. to 90.degree. C. to a second stripping column (NH.sub.3 stripping column), which is operated under a pressure of 1 to 4 bars and from which a gas mixture that is rich in NH.sub.3 is withdrawn as a head product. The gas mixture is scrubbed with water and ammonia and the NH.sub.3 gas which has been scrubbed is condensed.

Method of recovering ammonia from an aqueous effluent which contains NH.sub

The aqueous effluent liquors from gasification or de-gasification of coal are extracted with a water-insoluble solvent and the extract is processed to recover the solvent. The aqueous residue is treated to remove NH.sub.3 in a driving-off column. The invention adds the steps of

Processing aqueous effluent liquors from degasification or gasification

Monohydric and polyhydric phenols are removed from waste water together with hydrogen sulfide, free and combined ammonia, by extraction and distillation. The waste water is formed during the degasification or gasification of coal and is subsequently subjected to biological purification. The steps of the process are as follows:

Process for removing monohydric and polyhydric phenols from waste water

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Eschborn, Germany

Hans M Stonner