Undergraduate internships

Master 2 internship

re-dispersion of sedimentation sludge

L2IA and LSFC proposal (06/03 to 28/08/2023)

Sludges, as the residue of the final stages of industrial processes, whether from petroleum processing, mining, or recycling, are rarely simple systems to analyze and/or treat. They are diverse and varied in terms of their chemistry, the size of the agglomerates, and the origin of their concentration, forming a compact and heterogeneous system characterized by a dry mass and a certain quantity of water but also sometimes of residual solvent. They can be either mainly rich in mineral particles (e.g. sludge from mining elution) or rich in organic particles (sludge from wastewater treatment plants) - the latter can emit a gaseous release by bacterial decomposition or other oxidation reaction. Their management remains very complicated because often the process of transport or displacement of sludge in order to allow an analysis, a reprocessing, or a valorization can neither be that applied to a solid (because extremely divided) nor that of a fluid. In the first case, drying is extremely energy consuming because water or solvents are "trapped" in the matrix, and in the second case, fluidization does not allow a re-dispersion of particles but phase demixing which is also difficult to manage because it is not very predictable.

The objective of this internship project is therefore to study a model sludge formulated from the precipitation of insoluble salts and iron hydroxide forming aggregates of variable submicron size dispersible in the aqueous phase. The first step will be to study the stability of the system as a function of a variation in osmotic pressure and ionic strength and to correlate the viscosity of the solutions to the concentration regulated by these thermodynamic variables in the range of high concentrations. The kinetics of water recovery and re-dispersion will be evaluated with or without external stresses (pressure fields), as well as rheological aspects. 

The internship will be carried out between the L2IA and the LSFC and in close collaboration with the SEAD/LCBC laboratory of CEA Marcoule under the supervision of Arnaud Poulesquen and Jean-Baptiste Champenois.

For more information, please contact: Olivier DIAT (olivier.diat@cea.fr), Coralie PASQUIER (coralie.pasquier@cea.fr), or Rachel PFLIEGER (rachel.pflieger@cea.fr)