PURPOSE: To effectively break bubbles, by applying orgainc solvents to bubbles formed from a bubble separator, etc. in waste water treatment.

CONSTITUTION: Bubbles to be treated are introduced to a bubble breaking tank 1 by an introducing port 2. Introduced bubbles contact with orgainc solvents 3 (For example, methanol) by agitation treatment, are broken and are mixed into organic solvents. Gases introduced with bubbles are discharged outside the tank from a gas outlet 5. Liquor to be treated consisting of mixtures of organic solvents and bubble groken liquor is introduced to a solvent recovering tank 8 from a discharge valve 7. A fixed quantity of organic solvents are simultneously introduced to the bubble breaking tank by the opening of a valve 10 from a solvent storage tank 9. Liquor to be treated is heated by means of an electric heater 11 at the solvent recovering tank 8, and organic solvents are vaporized, changed into gas, recovered at a cooler 12, and retuned to the solvent storage tank 9. Bubble broken liquor separated from organic solvents id discharged from a discharge valve 14