Abstract: There is provided a waste water-treating method which comprises passing an aqueous liquid, in an upward direction and at a suitable flow velocity, through a bed consisting of activated carbon whose particle diameter ranges between 0.20 and 1.5 mm and whose width of particle size range (or substantial difference between the largest ones and the smallest ones) is chosen to be 0.30 mm or more, controlling the fluidized bed of the carbon to be expanded 1.2 to 3.0 times to form a particle size gradient of the activated carbon along the resultant fluidized bed.

Abstract: A method for the preparation of a porous carbon molding having a low apparent density, the method comprising the steps of thermally mixing a pitch, which has a softening point of 50.degree. - 350.degree. C, a carbon content of 80 - 97 wt%, a hydrogen/carbon ratio of 0.3-2.5 and a nitrobenzene-insoluble fraction of below 60 wt%, with at least one aromatic hydrocarbon having a boiling point of 200.degree. C or higher, forming the mixture into a suitable shape, immersing the formed material in a solvent, in which the pitch is hardly soluble but the aromatic hydrocarbon is easily soluble, for extracting the aromatic hydrocarbon from the formed material and obtaining a porous pitch material, oxidizing the porous pitch material at a temperature from room temperature to 400.degree. C by the use of an oxidizing agent to form an infusible porous pitch material, and calcining the infusible porous material in an inert atmosphere at a temperature higher than 600.degree. C to obtain a porous carbon material.