PURPOSE: To eliminate generated foam efficiently and to perform continuous operations without any trouble at a low cost by interrupting a heat source when a trouble arises in the operation by the generation of foams after starting distillation.

CONSTITUTION: Generated foam is eliminated by introducing the same into a tank having no heat sources or bringing the same into contact with liquid contaminated with solvents of low temp. supplied into an isolated tank or tub. More specifically, when liquid 7 contaminated with solvents is put into a bottom liquid tank 3 and is heated with a heating means 5, solvents and water cause azerotropy and the greater part are distilled later, but as the heating time passes by, foams 9 are generated. The generated foams build up and flow down into an another tank 4 beyond a partition wall. The foams which are extinct in the tank 4 form a slight amt. of liquid which accumulates little by little on the bottom, and when the amount attains to a certain amt. or above, the liquid is returned into a bottom liquid tank 3 and is redistilled, whereby distillation is continued.