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Thermal processes

The team is interested in the destruction or recovery of water and waste using thermal processes. The main distinction is whether or not an oxidant is present. In the presence of an oxidant, we study hydrothermal oxidation processes in pressurized water, in subcritical conditions with wet oxidation, and in supercritical conditions (in the latter case, mainly case studies in collaboration with industry). Oxidation leads to waste or pollution destruction. On the other hand, in the presence or limit of oxidants, plant matter can be valorized in the form of a material stream, a liquid such as bio-oil for sub-critical water liquefaction, or a gas (H2, CH4, CO) by gasification processes (for solids, at atmospheric pressure under dry steam flow and for effluents in a supercritical aqueous medium).

Two processes in particular are being studied in the laboratory:

Bubble column for wet oxidation:
The wet oxidation process: the innovative approach here is to focus on the fine characterization of bubble column implementation, at high pressure and temperature. The hydrodynamics of the liquid phase, retention of the gas phase and material transfer (by determining the interfacial area and the material transfer coefficient) are the main studied elements. For this process, we are also studying the possibility of coupling oxidation with fixed-bed biological treatment, in particular to improve the treatment of persistent molecules in the environment.
Bubble column flow (20 MPa, 100°C)
Dry gasification: a continuous bubbling fluidized bed is used to study heat and mass transfer coefficients within the bed and within the grain of the solid to be upgraded. Segregation on particles inhomogeneous in diameter and density is studied. The quality of the solids produced is an important issue, notably through the volatilization of heavy metals and the leaching behavior of the solid residue. Methodological and measurement tools are being developed to address these issues.
Finally, we are interested in developing non-destructive processes for the extraction of high value-added products using pressurized hot water, as a first way of adding value to plant matter.