PURPOSE: To separate a coating sludge under non-viscous and fluent condition, to perform smoothly the separation process to recovery and discard and to keep the circulation water of a booth clean for a long time.

CONSTITUTION: The surface layer part contg. coating sludge floating on the circulation water from a coating booth is sucked up through a tip with a function of sucking the surface layer part by means of a pump 5 to send it to a vibrational cylinder 6. Then, the sludge floating in a floating separation tank 12 is discharged into a discarding vehicle by means of a recovery device 14. A coating mist is desolvated and is made fluent by vigarous vibration when it passes through the vibrational cylinder wherein buffles 7 and 8 each with a hole 9 and 10 are alternatively piled up and as a number of ultrafine bubbles generated at the same time exhibit floating effect for making the sunk flowing mist float up, the whole booth is kept clean.