To provide an innovative recycling technique which is significantly advanced compared to a conventional technique from a technical point of view and brings about an enormous benefit to a nation and a society from an economic point of view as a technique for recycling a large quantity of waste which is produced when agricultural and marine products are used as foods or some other materials and has been the cause of environmental pollution because of the unavailableness of its disposal site, to obtain a high-performance and costly carbon adsorbent.

As a solution of this issue, the agricultural and marine resources such as vegetables, cereals, meats, sea weeds and fish are carbonized at 400-800°C to obtain a carbonaceous material. Further, this material is made to adsorb an aqueous sulfate solution of one kind or more selected from among copper, iron, manganese and zinc and a metallic ion is added to the material. After this step, the material is dried and crushed and a water-soluble polyvinyl alcohol and/or calcined plaster are added as a binder. Then the material is molded in a granular form and dried/cured to obtain the carbide. Also the developed method for manufacturing the carbonized material is provided.