Abstract: A continuously flowing fluid is processed by being fed to the top of a hydraulic downdraft column (17) which is of a height such that the pressure at the bottom thereof will approximately be at the pressure necessary to create supercritical water conditions. The fluid is conducted to the bottom of the column (17) and received in a reaction chamber (21) in which the majority of the fluid is recirculated around an annular baffle plate (24). The material in the reaction chamber (21) is heated to a temperature above that necessary to create supercritical water conditions by an independent reaction taking place in a heating chamber (32). The result is that the fluid will undergo chemical reactions at the supercritical temperature and pressure range and will be of a lower specific gravity than the unprocessed fluid.