Abstract: An apparatus which is suitable for the treatment of at least two liquid wastes which are chemically not compatible with one another, which comprises an addition zone for the addition of treatment substances to the wastes, a sedimentation zone for the separation of precipitates and liquid and a dilution zone in which the liquid separated off in the sedimentation zone is diluted with water and the liquid diluted in this way is run off, is improved by that, for each of the liquid wastes which are chemically not compatible with one another, separate chambers are provided in the addition zone and in the sedimentation zone, that the addition zone is located lowest in the apparatus, the dilution zone is located above the addition zone and the sedimentation zone is located above the dilution zone, that to each of the chambers of the addition zone there is allotted an inlet for treatment substances which can make the waste in question compatible with the other waste or the other wastes, that each of the chambers of th