Taking river samples from a bridge (Orléans, 2023)
© BRGM - P. Moreau
Issues and needs
Monitoring operations carried out on rivers and groundwater show that certain organic micro-pollutants are present in the water (for example, pharmaceutical molecules, plastic residues such as bisphenols, pesticides, etc.). Some of these molecules are ubiquitous, persistent, biologically active and/or endocrine disruptors. Their presence could notably be due to insufficient abatement (i.e. reduction in their concentration) in wastewater treatment plants. In view of this situation, more effective ecological processes need to be developed to reduce the discharge of these molecules into the environment, especially since treated wastewater can be used to water vegetation in public spaces, particularly parks and gardens. This kind of wastewater-reuse system, which has notably been implemented by the Orléans Metropolitan Council (a partner in this project) has several advantages in the face of growing pressure on water resources.
Within this context, the BIOSEPUR project aims to:
- develop new activated carbons and biochars from non-recycled lignocellulosic agricultural waste from the Centre-Val de Loire region, and test them in real water treatment conditions,
- assess the impact of this reuse system on the soil and groundwater affected by the watering of the Parc Floral de la Source with treated water from the neighbouring treatment plant.
Raw materials tested as part of the BIOSEPUR project and the corresponding activated carbons
© ICMN - Benoit Cagnon et Antoissi Mohamed-Ali
Initial results
For the purposes of the BIOSEPUR project, several activated carbons and types of biochar were developed from lignocellulosic precursors and their properties compared with those of commercial products. The raw materials – namely agricultural residues of rape-seed straw, flax and switchgrass – were supplied by the Chamber of Agriculture of the Cher département. They were transformed into activated carbons using various processes. Adsorption kinetics and adsorption isotherms of carbamazepine and sulfamethoxazole (target pollutants) were used to estimate the adsorption capacity of these porous materials.
These biomaterials need to meet several objectives, in terms of economic and environmental performance, and of their efficiency in terms of the treatment of the target molecules. After the laboratory characterisation phase, the plan is to test them in real water treatment conditions and monitor their abatement capacity. In parallel with this study aimed at optimising the production of activated carbons from agricultural residues, continuous adsorption tests on activated carbon columns were carried out to optimise the parameters (flow rates, column height, mass of activated carbon, etc.). These tests were performed using commercial activated carbons supplied by Jacobi Carbons, the project's industrial partner.
Soil sampling (Orléans, 2024)
© BRGM - P. Moreau
As regards the second component of the project, the aim is to assess the impact of the wastewater-reuse system on the receiving environment: soil and groundwater. The Parc Floral de la Source in Orléans was chosen as the study site because it is watered during summer with treated water from the nearby wastewater treatment plant. The sorption characteristics of the molecules targeted by the project (AMPA, benzotriazole and atenolol) need to be assessed through laboratory experiments under equilibrium conditions and/or under flow conditions.
Several soil samples were taken at different locations in the Parc. Kinetic and thermodynamic (isotherms) sorption studies of the molecules benzotriazole, atenolol and AMPA were carried out on two of these soil samples.
BRGM's role
BRGM is project leader for the studies concerning the transfer of the target molecules into the soils of the Parc Floral and is therefore in charge of carrying out all the experiments and analyses for this part of the project.
The analyses of the project's target molecules under environmental conditions are also carried out in BRGM laboratories.
Partners
BRGM is one of 6 partners in the BIOSEPUR project (using BIOmass and Soil treatment to PURify wastewater), a research project of regional interest, funded by the Centre-Val de Loire region (agreement no. 2022 - 00150391). The project began in October 2022 and will run for 46 months. It is coordinated by the Interfaces, Confinement, Materials and Nanostructures (ICMN) laboratory, a Joint Research Unit (UMR) involving CNRS and the University of Orléans.
- Interfaces, Confinement, Materials and Nanostructures (ICMN - UMR 7374 CNRS), project coordinator
- BRGM - Water Department
- JACOBI CARBONS France
- Orléans Métropole
- Chamber of Agriculture of the Cher département
- Institute of Combustion, Aerothermics, Reactivity and Environment (ICARE)
