ABSTRACT
Biomass and waste biomass are promising renewable energy sources and investigations regarding its utilization are being enhanced. Supercritical water is located above the critical temperature of 374°C and critical pressure of 22.1 MPa. Subcritical water is located below 374°C and above the saturated vapor pressure at this temperature. High-pressure superheated steam is either located above 374°C and below 22.1 MPa or less than 374°C and its saturated vapor pressure. The oxidation condition could be changed from supercritical water to high-pressure superheated steam without a significant decrease on the degradation power of organic compounds, which is strongly dependent on the temperature than the pressure in the high-temperature and high-pressure region. The main elements of carbon, hydrogen, and nitrogen in waste biomass are decomposed into CO2, water, and N2 gas by supercritical water oxidation. However, these treatment conditions require high temperature and pressure above the critical point of water.
