The evaporation process has recently gained new momentum through special applications in chemical engineering and especially in environmental engineering, e.g. in the recovery of materials of value from liquid production residues. Thin-layer evaporators with rotating wipers are particularly suitable for such tasks if the products of interest are thermally unstable or are prone to crusting. If these applications involve distillation-type separation then a knowledge of the expected separation effect is important for calculations. This article aims to make a contribution to this topic. It is based on experimental studies performed on a laboratory-scale thin-layer evaporator and on earlier treatments of the theory of distillation in thin-layer evaporators with a mechanically generated liquid film.