PURPOSE: To decrease untreated parts where flow of air does not act and polluted materials are not recovered by relatively fluctuating the force for feeding the air and the force to suck out the air in the case where the air is fed into the ground to gasify the polluted materials in liquid strata and is sucked out together with these materials onto the ground surface.
CONSTITUTION: While the air is first fed into a conduit 2 of an air injection well cylinder A by operating a variable type fan 4 thereof, a variable type vacuum pump 6 of a vacuum extraction well cylinder B is operated to suck the air out of this conduit 2 at the time of recovering the polluted materials under the ground surface. Namely, the air is delivered from air flow holes 2a through packing materials 3 for ventilation into the ground and is brought into contact with the polluted materials of a liquid phase to gasify these materials; thereafter, the air is sucked out together with these materials. At this time, the force to feed the air and the force to suck out the air are continuously or intermittently and relatively fluctuated. Namely, the pressure balance of both is broken by the relative fluctuation, by which the flow passages of the air in the ground are changed. As a result, the untreated parts where flow of the air does not act and the polluted materials are not recovered are decreased.
YASUDA MASATO
WATANABE YOSHIYUKI
