Bioclogging Reduction during Groundwater Recharge Using Hydrogen Peroxide: Pore- and Column-Scale Experimental Observations and Reactive Transport Modeling

We experimentally simulated a groundwater recharge operation using treated wastewater and investigated the efficiency of a hydrogen peroxide (H2O2) treatment in disrupting biofilm area coverage, restoring medium porosity, and mitigating bioclogging. We combined multiscale experiments with reactive transport modeling to predict permeability evolution. Detailed pore-scale observations from microfluidic experiments show a rapid decrease in biofilm area coverage at the onset of the treatment, followed by stabilization over time. By the end of the treatment, porosity increased from an initial value of 0.349 to 0.496, which corresponds to 82.6% of the original medium porosity in the absence of biofilm. At the continuum scale, soil column experiments showed hydraulic conductivity recovery and reduced bacterial concentrations, quantified from DNA copies by using PMA-qPCR analysis. Bacterial survival rates, determined from live–dead assays based on flow cytometry, show a pronounced decrease across the column experiments treated with H2O2, indicating the penetrative effectiveness of the treatment. Additionally, we used a reactive transport model that accurately matched the permeability evolution by capturing the biogeochemical dynamics during the experiments. Model results indicate that the time to reach maximum permeability recovery is influenced by the soil and biofilm responses during the early stages of the treatment.