Abstract: An apparatus and method for treating materials that present disposal problems is provided. The treatment takes place within an aqueous stream and in an oxygen-deficient multiple zone system, and results in the thermal decomposition and/or separation of components within the treated material. The apparatus and method of this invention may be used for the treatment of non-hazardous and hazardous waste, including organic and inorganic compounds, radioactive materials, toxic compounds, binary chemicals (such as nerve gas) and heavy metals, prior to disposal.