Direct Numerical Simulation of Solute Transport in Bioclogged Porous Media

Biofilms in porous media significantly impact solute transport, beyond their role in reducing permeability through bioclogging. Experimental evidence has shown that biofilms can induce anomalous transport behaviors such as increased dispersion and pronounced tailing. These effects arise from the structural heterogeneity of the biofilm and the development of internal convective pathways. Despite being mostly composed of water, biofilms exhibit reduced effective diffusivity due to their complex microstructure. To capture these effects, we develop an original pore-scale transport model combining the micro-continuum approach with Random Walk Particle Tracking. Our simulations show that biofilm permeability, effective diffusivity, and spatial heterogeneity strongly influence solute breakthrough times, highlighting the critical role of biofilm structure in shaping complex transport behavior in porous systems.