Modeling salinity-dependent transport of viruses in porous media

Abstract

Water contamination by pathogenic microbial species is the cause of serious outbreaks of water-borne diseases in coastal urban areas. Upon their discharge into surface water, e.g., estuaries, they may reach the bottom sediments, accumulate (i.e., attachment) under favorable conditions, and be displaced (i.e., detachment) when those conditions are reversed. Current models do not account for coupled transport of microorganism in porous media with salinity, not allowing, therefore, to predict transport behavior under variable chemical conditions.In this paper, a coupled model of transport in porous media of pathogenic microorganisms, such as viruses, and salinity is presented. Upon verification of the model with the analytical solution derived in this work and validation with the experimental data from the literature, simulations of tidal variation of flow and transport were performed. Results show a discrepancy in the transport behavior of viruses predicted by our model and the classical approach. In particular, our results show a peak of virus concentration when a contaminated saline system is flooded by a low salinity water. The peak is due to virus detachment from the porous medium surface upon salinity reduction. The magnitude of the peak can be up to one order of magnitude of the initial concentration within the medium. Suggesting a negative feedback from tidal flow in coastal aquifers nearby estuaries affected by virus contamination, which is not predicted by classical models.