SCWO

Supercritical Water Oxidation (SCWO) is a thermochemical process that uses water above its critical point as a solvent and reaction medium to oxidize organic wastes into carbon dioxide, water, and inorganic salts. In the supercritical state, water has altered solvent properties that enable rapid, complete oxidation at relatively short residence times.

Operationally, SCWO requires temperatures typically around 400–650°C and pressures of 25–30 MPa (roughly 250–300 bar). The feed, often an organic-rich waste stream, is brought to supercritical conditions in the presence of an oxidant such as oxygen or air, sometimes aided by hydrogen peroxide.

Advantages include high destruction efficiency for a broad range of organics, including some chlorinated compounds, and the potential for small reactor volumes and minimal secondary waste. Limitations include severe corrosion and materials challenges, high capital and operating costs, and safety concerns associated with high-pressure, high-oxygen service.

Applications span hazardous waste treatment, chemical manufacturing effluents, and certain wastewater streams containing refractory organics. Commercial deployment remains limited due to cost and reliability, though pilot and demonstration plants have operated, advancing materials and process control for future scale-up.

History and development notes that SCWO research began in the late 20th century, with pilot facilities built in the 1990s and 2000s. Ongoing work focuses on material durability, catalysts, energy integration, and safe handling of oxidants to improve practicality and environmental performance.