PURPOSE: To simplify the structure and simultaneously use a plurality of drain ports by providing a blower to feed gas in the direction of the sewage tank in a drain pipe, and transporting drain so as not to fill the drain pipe.

CONSTITUTION: When drain charged in the drain inflow ports 42 of drain ports 41 flows in a drain pipe 21, air from a blower 31 is brought in contact with the surface of the drain and the drain is transported to a sewage tank side. When the drain reaches the vertical part 24 of the drain pipe 21, air blasting is suddenly in its direction by colliding with the curved wall, air flow becomes turbulent severely, hence the whole drain is stirred into water drops, and floatingly transported upward in the vertical part 24 together with air blasting. Further, the drain is separated into air and water content by means of a cyclone separator 12, the air is slowed and released into the atmosphere, and the water content is received in the sewage tank 11. Hereby, airtightness of the device can be easily held.