Understanding SCWO

What does supercritical mean?

Matter exists in many states. The most usual ones are solid, liquid and gaseous states, which vary based on temperatures and pressures applied. (E.g. water : solid = ice, gas = vapour)

The molecules have their own “critical point” which corresponds to specific temperatures and pressures beyond which the particles behave differently and the matter is henceforth said to be in a “supercritical” state.

In this phase, the matter’s properties change and offer new possibilities for science and industry.

Supercritical water properties : the supercritical point of water is at a pressure of 221 bars and a temperature of 374°C. At such a supercritical temperature and pressure, water acquires radically different physical properties to its usual liquid phase:

  • Water behaves like a powerful solvent for all organic substances (e.g. oil mixes with water)
  • Oxygen completely dissolves in water
  • Mineral salts that are highly soluble in liquid water precipitate under supercritical conditions

Supercritical CO2 is relatively simple to manage and is already used in many industrial applications (extracting plant flavours, manufacturing coffee, etc.). Using supercritical water is more complicated as it requires higher temperatures and pressures but it opens up applications in many different sectors, particularly the treatment and recovery of industrial waste.

The SCWO process

  • Once an aqueous effluent (water + pollutant) is subjected to temperature and pressure, water subsequently takes on a supercritical state
  • O2 injection (using expertise from our partner, Air Liquide) creates an oxidation reaction which generates heat to warm the waste at the inlet and provide surplus energy for the client facility
  • Destruction of all organic matter (approx. 99.9%)
  • Recovery of clean water for the client’s needs (cleaning, cooling, etc.) or for discharge into the natural environment (compliance with discharge thresholds)
  • Recovery of surplus energy for the client process (vapour, heating)

Metallic coumpounds

Organosulfur compounds

Basic organic compound

Nitrated organic compounds

Basic organic compound