PURPOSE: To bring always the objective liquid to be treated into contact with solid substance in slurry state and to increase the solid-liquid contacting efficiency by charging previously the objective liquid to be treated in a packed tower, thereafter packing the solid substance therein and performing the solid-liquid contact.

CONSTITUTION: The objective liquid to be treated is charged via a pipe 4 into a packed tower 1 in which a filtration sand bed 8 is provided to the bottom and liquid is circulated with a slurry pump 2 through the pipes 5, 6. Next, solid substance of prescribed quantity, for example, activated clay is divided and packed into the liquid forcedly stirred through a pipe 7. The packing time is preferably prolonged as much as possible so as not to form the block of activated clay. For example, about 1W20 tons activated clay are packed portion wise in the range of about 2W15 hours. Thus, the activated clay can be homogeneously dispersed into the fluidizing liquid and the air mixed together therein is discharged to the outer part from the surface of the liquid.