Flagship project / Pollutant studies: scaling up research with PRIME
A true in vitro soil laboratory. This is an apt description of PRIME (Platform for remediation and innovation in environmental metrology), which has been developed by BRGM engineers and researchers. In situ research has many limitations, and scientists are better able to study the effects of various techniques by first mastering them in the laboratory. Soil contamination, particularly from mining and industrial operations, is a critical environmental, health and economic issue. In France alone, more than 7,200 sites have been contaminated with heavy metals (lead, copper, chromium), hydrocarbons or organochlorine compounds (pesticides, solvents).
Initiated and financed by the Centre-Val de Loire Region, the French government and the European Regional Development Fund, PRIME has been part of BRGM’s Platforms for environmental innovation, development and technological optimisation (PIVOTS) programme since its inauguration. PRIME is nothing less than the very first physical simulator of a surface environment. It produces a fully controlled replica of the environment in the laboratory, in order to understand how it works, test decontamination processes and perform modelling, with a view to carrying out diagnostics, characterisations and treatment.
By integrating experiments on different scales, from a few centimetres to tens of metres, the platform can realistically simulate an environment from the ground surface down to the water table, in order to study pollutant transport and physico-chemical and microbiological transformations, thereby facilitating decontamination.
Centimetric and multimetric pilot testing facilities
The platform brings together experimental pilot apparatus from the centimetric to multimetric scale, as well as analytical capabilities for developing, validating and qualifying environmental metrology and decontamination tools and methods. The key to this type of simulator is the continuum of study, regardless of scale. This makes it highly innovative and unique compared to existing platforms. With a process for treating degraded soil (polluted soil, mining technosol, etc.), if you want to move from concept to full-scale implementation, you need to manage the various scale changes, from both a technical and an economic point of view. On this occasion, researchers were able to develop technologies that are difficult to study in situ. The multimetric pilot plant’s effective volume of approximately 120 m³ enables reaction processes occurring in areas that are unsaturated or saturated with water to be analysed on a large scale and in 3D.
With its modular design and numerous sensors, BRGM’s multimetric pilot plant could potentially be made available to other research establishments and companies, to enable them to conduct their experiments under conditions that are close to reality but fully controlled, and that provide more robust results than an on-site pilot study.
Degraded sites reproduced in the laboratory
Several types of degraded environments have already been studied. For example, at the submetric (i.e. centimetre) scale, work has been done on cleaning up volatile organic compound pollution in the form of residual saturation in subsurface porosity. So-called "2D" tanks have been used to study the effect of pumping pure organic phases with chemical (surfactants, foams or gels) or thermal aids, which makes it technically possible to reduce capillary effects and adapt viscosities and pressures in order to increase purification performance.
BRGM was also able to study the effect of mining technosol amendments to encourage the growth of plant cover to limit erosion phenomena and phytostabilise certain pollutants (lead, zinc, arsenic, etc.), on a metric scale, in a controlled environment reproducing conditions in both unsaturated and saturated zones. Amendments are materials added to soil to improve its quality. Lastly, the multimetric scale will be useful for studying organic phases that are lighter than water (hydrocarbons such as diesel fuel, for example) and denser than water (such as chlorinated solvents).
Its modular construction and these original multi-scale analytical and experimental devices make PRIME a unique platform in Europe. Its use could be extended to research other issues such as pollution, but also to validate the performance of direct and indirect measurement/analysis instruments (such as geophysical tools) and decontamination processes.