Investigating the Effect of Bioclogging on Electrical and Flow and Transport Properties of Porous Media.

In many natural and engineered contaminant remediation systems, microbial growth and biomass accumulation can lead to pore clogging and cause significant changes in the flow and transport properties of the porous media (Seifert and Engesgaard, 2007; Brovelli et al., 2009). Bioclogging in porous media may result from accumulation of bacterial cells in the pore space, from biofilm development, or from excretion of extra-cellular polymers (Vandevivere and Baveye, 1992; Rinck-feiffer, 2000). Recent advances in biogeophysical investigations have demonstrated the potential of geophysical techniques to elucidate microbial processes both in the laboratory and in the field (Atekwana and Slater, 2009). In the present study, flow through sand columns inoculated with Pseudomonas aeruginosa wild type (PAO1 Gfp), which is a model biofilm forming microorganism were used to investigate the effect of bioclogging on the complex conductivity and flow and transport properties. Our main objective is to determine how bioclogging manifests in the electrical properties of sands. Our secondary objective is to determine how complex conductivity relates to changes in hydraulic conductivity, which is a key parameter needed to model flow and transport in porous media. Our results suggest that bioclogging resulting from increases in microbial cell concentration and the production of exopolymeric substances (EPS) had a large impact on the imaginary conductivity, hydraulic conductivity, and porosity.