PURPOSE: To obtain the method which nearly completely treat a dioxine-contg. liquid with a simple device and use of just a small amt. of drugs by adding an alkaline agent to the dioxine-contg. liquid to neutralize the liquid, and adjust the liquid to specific pH and solvent-extracting the dioxine as lipophilic dioxin into a hydrocarbon solvent.

CONSTITUTION: The alkaline agent is added to the dioxine-contg. liquid to adjust the pH of the liquid to alkalinity, more preferably ≥11.0pH and to denauture the dioxine so that the dioxine is made lipophilic in the hydrocarbon solvent as well. Kerosine- or tapionel-based foaming agent is then added at a concn. of 10 to 1000ppm to the liquid and the froth is separated by a froth separator to thicken and separate the dioxine into the froth. This froth is supplied to a cleaning tank where a solid content is separated. The resulted supernatant liquid is fed to a solvent extraction chamber where the liquid is stirred in contact with the kerosine solvent contg. ether to transfer the dioxine in the supernatant liquid into the solvent phase; thereafter, the solvent phase is separated. The solvent phase is then supplied to a scrubbing device and is subjected to water scrubbing by which the solvent phase is reverse extracted into the water phase. This dioxine concentrate is brought into contact with an active carbon layer, by which the dioxine is adsorbed and separated. The dioxine is thus recovered.