Abstract: This invention relates to a method for treating various kinds of drain water and waste liquid which treatment now becomes a problem, for example, drain water and waste liquid containing hardly removable phosphorus and nitrogen, waste liquid containing organochlorine compounds such as tetrachloroethylene, etc., excretive drain water from a piggery containing organonitrogen compounds at a high level, waste liquid containing heavy metals such as lead, hexavalent chromium, cadmium and the like, drain water from dairy product plants, fishery processing plants, slaughterhouses, etc. which contains water soluble protein at a high level, drain water from pulp plants, photo developing waste liquid, car wash drain water containing a mixture of car polishing wax and detergent and the like by the use of porous ceramics provided with amorphous pore surfaces.