【Special Issues: Recycling and Resourse Recovery of Inorganic Solid Wastes】
Hydrothermal Dynamicsand Waste Treatment
――Recycling and Recovery of Inorganic Materials based on Earth Principle――
Nakamichi Yamasaki
Tohoku University, Graduate School of Environmental Studies
（Aoba 20, Sendai, 980-8579 Japan）

Abstract
In order to establish a sustainable society, with practical material recycling, it is appropriate to focus on a range of guiding “Earth principles”, including the character and application of hydro-thermal processes. This paper demonstrated how information obtained from the study of fundamental Earth principles can be used to inspire the development of new methods for material recycling. For example: 1）Hydrothermal hot-pressing processes, simulating the formation of sedimentary rock sequences, can be used for the solidification of toxic and hazardous materials; 2）Organic materials could be formed from CO2 under hydrothermal conditions（using Fe and Ni metals, and low valence Fe oxides）, at temperature and pressure conditions consistent with a subduction（tectonic）setting, such as（under Japan）where the Pacific Plate sinks beneath the（Eurasian）continental plate.

Key words: hydrothermal, recycle, earth science, Co2, Artificial sedimentary rock