Flow velocity impact on biofilm development in subsurface environments - A laboratory experiment
Résumé
Biofilm development is the result of complex interactions between structural, physical, chemical and biological properties. Natural circulation of chemically rich water in subsurface environments both promotes and limits biofilm growth, with a strong impact on its shape and reactivity. Understanding the interaction between hydrodynamic processes and biofilm properties requires more experimental and modeling investigations. We propose an experimental approach to study the relationship between hydrodynamic parameters and reactivity at the pore-scale. The experimental set-up allows monitoring denitrification process for nitrate rich site water passing continuously through plastic tubes for several flow velocities. This idealized 1D flow experiment enables to reproduce pore-scale interactions between flow velocity and biological activities in natural conditions. The observed dynamic of nitrate transformation is related to different evolution of the biofilm structure and illustrates the impact of flow velocity on biofilm growth and shape. It leads to identify several regimes at the different phases of the biofilm development where flow velocity is a determinant factor for biofilm stability and performance.