Reference : UMR7327-MARROU0-024
Workplace : ORLEANS
Date of publication : Tuesday, May 3, 2022
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 October 2022
Proportion of work : Full time
Remuneration : 2 663 € gross monthly
Desired level of education : PhD
Experience required : 1 to 4 years
Soils, sediments and groundwater are increasingly endangered by anthropogenic contamination, especially industrial pollutants from accidental spills, leaks or improper management. In France, more than 7000 sites are currently reported as being strongly polluted by heavy metals, nitrates, and persistent organic pollutants (e.g., non-aqueous phase liquids-NAPLs, pesticides). Among persistent organic pollutants, chlorinated solvents (dense NAPLs), and petroleum hydrocarbons (e.g., light NAPLs) are known to be toxic and carcinogenic for humans, and their contamination of soils and aquifers is of great environmental concern because they cause damage to ecosystems and to soil and groundwater. Light-NAPLs have a tendency to stay at the top of the water table because they have a density lower than that of water and a low water solubility. They are highly volatile and very slow to degrade naturally because the residual phase is trapped in the smear zone between the vadose zone and the aquifer and they are not completely dissolved in the plume. In the context of the ecological transition, there is an urgent need to develop efficient and sustainable remediation techniques to clean up sites contaminated by LNAPLs.
In situ bioremediation, also named natural attenuation, is a major method employed in the restoration of petroleum hydrocarbon polluted environments because it is eco-friendly and economic. It consists in changing environmental conditions (e.g., pH, temperature, water content, salinity, oxygen availability and nutrients) in order to stimulate growth of microorganisms degrading organic pollutants to less toxic compounds or removing them without adversely affecting the environment. During in situ bioremediation, oleophilic bacteria in soils, sediments and groundwater use carbon-rich petroleum compounds as their primary source of energy or assimilate them into cell biomass. Due to its cost-saving potential and the environmental benefit of in situ techniques compared to conventional ex situ techniques, the interest of commercial providers for enhanced bioremediation is steadily increasing.
The research proposed in this postdoctorate concerns the development of quantitative mechanistic multi-scale models capturing the biodegradation processes of non-aqueous phase liquid contaminants and simulating the resulting response of the porous medium to an applied alternative current under a wide range of parameters including pH, flow rates, contaminant composition, and rock microstructure. In particular, the candidate will consider the transport, trapping and remobilisation of NAPLs as well as biogeochemical and electrostatic events. A step-wise strategy will be adopted focusing first on single-phase flow simulations, and considering then the coupling with multiphase flow and biodegradation. For this purpose, the candidate will adapt the Continuous Species Transfer technique to model the change of volume of NAPL droplets due to reactions at the interface between the water and the contaminant. The candidate will combine the advanced multiscale (i.e. pore-scale, hybrid-scale and field-scale) OpenFOAM-based simulator developed by the Porous Media Research group at Earth Sciences Institute of Orléans with biogeochemical and electrostatic models using the PHREEQC software. The multi-scale numerical models will be compared with high-fidelity datasets developed by our partners using microfluidic experiments and geophysical and biogeochemical data measured on a plurimetric pilot.
You have a PhD's degree in Fluid Dynamics, Flow and Transport in Porous Media, Computational Science. Good programming skills with fluency in C++ are expected. Knowledge of OpenFOAM and interest in geochemistry are a plus.
The candidate will:
Review the literature on theory and numerical modeling of in situ bioremediation in unsaturated porous media,
Develop a multi-scale simulator using OpenFOAM and PHREEQC to model the in situ bioremediation mechanisms and identify the key parameters controlling the processes,
Verify the predictive capacity of the numerical models using high-fidelity experimental data,
Upscale the processes to larger scales,
Publish your results in high-impact scientific journals and participate in international conferences
The position is located in Orléans, France at the Earth Sciences Institute of Orléans (ISTO). The candidate will receive a PhD degree from University of Orléans. The PhD project is part of IMAGE, a project funded by the French National Agency for Research, that aims at deciphering the electric signature of processes associated with in-situ bioremediation. IMAGE is a consortium of academic and industrial partners including ISTO, BRGM (French Geological Survey), Sorbonne University, Geosciences Rennes, and IRIS Instrument.
ISTO is a joint research laboratory between CNRS, University of Orléans, and BRGM located on the Geosciences campus of Orléans close to Paris, France. The Porous Media Research Group develops cutting-edge research and worldwide recognized expertise on multi-scale modelling and microfluidic experiments of multiphase flow and reactive transport in geological formations.
The candidate will join a network of leading-edge national research institutions including CNRS, BRGM, Sorbonne University, Geosciences Rennes, University of Bordeaux, and Université de Pau et des Pays de l'Adour, and international collaborations including Heriot-Watt University, Julich Forschungszentrum, Lawrence Berkeley National Laboratory, Princeton University, and Stanford University.
The postdoc fellowship is a 1-year contract (renewable)
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