PURPOSE: To obtain clarifying action more efficient than heretofore in the effective decomposing and clarifying treatment of microorganisms by providing a curved tubular body which has ascending slope to the aperture of an outlet positioned in the liquid to be treated in a dispersion tank and equipping an air blowing pipe means provided in the comparatively low position of the ascending slope part.

CONSTITUTION: The inlet aperture P1 of a tubular passage (p) is provided in the position nearly lower than the surface of liquid to be treated. The tubular passage (p) is gradually lowered from the inlet aperture P1. Successively a tubular body 2a is curved so that it becomes ascending slope to an output aperture P2 positioned in liquid W to be treated in a dispersion tank 3. An air blowing pipe means 2b is provided in the comparatively low position of the ascending slope part. When air is blasted from the air blowing means 2b, floating fats and oils in a treating tank 1 are sucked from the inlet aperture P1 by action of air. These are violently agitated and mixed by bubbling action of the blasted air, pulverized and discharged from the outlet aperture P2. Further the liquid W to be treated is discharged together with air and generates a water flow. Pulverized fats and oils are efficiently dispersed by the water flow and the liquid to be treated is sufficiently aerated and treated.