Abstract A study of the feasibility of subjecting organic substances in waste waters to pyrolysis prior to their employment in purification of the water itself is reported. Refinery wastes and those from a biochemical industry were examined. In the case of the refinery wastes, oil filtered on sand granules was carbonized in various gas atmospheres for various periods. The quality of the carbon obtained was determined with reference to its oil-carbon transformation yield, adsorption capacity, and residual hydrocarbon content, comparison being made with a commercial active carbon. Carbon from biochemical wastes was obtained by pyrolysis of the mycelium after fermentation and filtration. This process is promising in that an improvement in the system used for the sludges disposal is required to obtain the active carbon required for the treatment of wastes.