Expérimentation et modélisation CFD du transport des microparticules de plastique au passage d'un déversoir d'orage

Microplastics (MPs) transport is strongly influenced by their characteristics (density, shape, size…), flow conditions (velocity, turbulent kinetic energy…), and also their interaction with dissolved and suspended organic or inorganic matter that likely leads to aggregates and thus change their density and size during their transport. Various Tasks in the ANR program termed "TRANSPLAST" are devoted to describe and characterize these properties and effects. It is also necessary to incorporate key processes (including aggregation, dispersion, settling, resuspension) in numerical modelling by means of user define functions and DPM (discret phase miodels) approach to better simulate MPs transport. It will then be possible, for any combined sewer overflow structuctures (CSOs) geometry, to mimic real MPs transport and to provide operating transfer functions that can be implemented into systemic models at the catchment scale. Multiphase flows using clean and real waters in the two main geometries investigated (lateral CSO and Stilling chamber based - CSO) will be simulated. The following parts give details on the main stages followed in the PhD investigations.

1) Advanced numerical modelling of convection, dispersion, settling and resuspension of MPs in CSOs will be developed and evaluated using data from others Tasks, based on the numerical developments performed in the framework of a previous ANR program led by DEEP laboratory. Computational Fluid Dynamics (CFD) approach including DPM (discret phase model) will be developed integrating all transport mechanisms and chemical factors. This new model will be evaluated against data collected in other tasks on the program.

2) the second step will be dedicated to the implementation of interaction functions such as the kinetic of aggregation in the CFD model developed in the first step. User defined function will be used to account for aggregation or change in settling velocity of MPs. Data deriving from other tasks will be used to test and validate this new model, particularly to reproduce the trapping efficiency of DSM structure (stilling basin based-CSO) when urban effluent is used.

3) the validated CFD models will be used to design an original stilling basin (adaptation of the geometry of DSM prototype) for MPs interception by means of settling processes. Indeed, settling technologies without additives are relevant compact facilities for CSOs discharges treatment. Preliminary results obtained by LEHNA demonstrated that MPs are trapped in sediments. Their interactions with other conveyed suspended solids and the appropriate hydrodynamic conditions (based on the increasing of the hydraulic residence time) may lead to their entrapment in sediments. The most appropriate designs of trapping structures will be also tested and validated experimentally.

Deliverables: Deliverables based on PhD works: 1) Key factors and mechanisms affecting the MPs distribution across CSOs ; 2) Key factors and mechanisms affecting the MPs interception in the DSM technology ; 3) Design of the original stilling basin to intercept MPs conveyed in CSO.

References: 

Botturi, A.; Ozbayram, E. G.; Tondera, K.; Gilbert, N. I.; Rouault, P.; Caradot, N.; Gutierrez, O.; Daneshgar, S.; Frison, N.; Akyol, Ç.; Foglia, A.; Eusebi, A. L.; Fatone, F. Critical Reviews in Environ. Sci. and Tech. 2021, 51 (15), 1585–1618. https://doi.org/10.1080/10643389.2020.1757957.

Han, Z.; Su, B.; Li, Y.; Dou, J.; Wang, W.; Zhao, L. Modeling the Progressive Entrainment of Bed Sediment by Viscous Debris Flows Using the Three-Dimensional SC-HBP-SPH Method. Water Research 2020, 182, 116031. https://doi.org/10.1016/j.watres.2020.116031.

Liu, F.; Olesen, K. B.; Borregaard, A. R.; Vollertsen, J. Microplastics in Urban and Highway Stormwater Retention Ponds. Science of The Total Environment 2019, 671, 992–1000. https://doi.org/10.1016/j.scitotenv.2019.03.416.

Zhu, X.; Chatain, V.; Gautier, M.; Blanc-Biscarat, D.; Delolme, C.; Dumont, N.; Aubin, J.-B.; Lipeme Kouyi, G. Combination of Lagrangian Discrete Phase Model and Sediment Physico-Chemical Characteristics for the Prediction of the Distribution of Trace Metal Contamination in a Stormwater Detention Basin. Science of The Total Environment 2020, 698, 134263. https://doi.org/10.1016/j.scitotenv.2019.134263.

Yan, H.; Vosswinkel, N.; Ebbert, S.; Lipeme Kouyi, G.; Mohn, R.; Uhl, M.; Bertrand-Krajewski, J.-L. Numerical Investigation of Particles’ Transport, Deposition and Resuspension under Unsteady Conditions in Constructed Stormwater Ponds. Environ Sci Eur 2020, 32 (1), 76. https://doi.org/10.1186/s12302-020-00349-y.

DEEP est un laboratoire de recherche de l’INSA de Lyon dont les compétences en ingénierie environnementale sont mobilisées pour répondre aux enjeux des transitions écologiques et énergétiques.

Notre vision est de préfigurer la gestion des rejets de demain en aidant au développement d’écotechnologies innovantes, compactes, économes en énergie, et intelligentes. Ce projet est décliné autour de 4 thématiques :

i) La réduction des émissions polluantes; ii) La réutilisation des eaux et des déchets ; iii) La récupération et la valorisation des ressources ; L’innovation digitale

- Ingénieur-e ou Master 2 en hydrologie urbaine, hydraulique, mécanique des fluides

- maîtrise de la modélisation CFD (compuational fluid dynamics), modèle DPM

- maitrise des méthodes d'échantillonnage

- Maitrise du fonctionnement des réseaux d'assainissement

- Bases solides en mécanique des fluides, en hydraulique, en modélisation numérique, en débitmétrie (différentes méthodes de mesure de débit)

- Aisance à l'orale

-Qualité rédactionnelle avérée

- Savoir-Etre (ponctualité, rigueur et éthique scientifiques)