Abstract: The method of feeding an insoluble organic solid material in the form of an organic resin or biological matter containing contaminating material such as radioactive waste from a nuclear facility or from treatment of animal or plant tissue in a laboratory or medical facility into a vessel containing water and to which ultraviolet light and ozone, preferably by sparging, are applied while the water is being agitated to distribute the ozone. The ozone oxidizes the organic resin or biological material, which disintegrates on oxidation substantially into water and carbon dioxide, leaving substantially no resin or biological material after treatment by the ultraviolet light and ozone for a prescribed period of time, and leaving the contaminant material as a precipitate or in solution in the remaining water or as an escaping gas, in any of which forms it can be readily separated from the water for disposal or further treatment.