Pore-Network Modeling of Solute Transport and Biofilm Growth in Porous Media

Chao-Zhong Qin,S Majid Hassanizadeh

doi:10.1007/s11242-015-0546-1

Chao-Zhong Qin, S Majid Hassanizadeh

Open Access

https://doi.org/10.1007/s11242-015-0546-1

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Journal: Transport in Porous Media	Publication Date: Sep 5, 2015
Citations: 35	License type: CC BY 4.0

Affiliation: Utrecht University

Abstract

In this work, a pore-network (PN) model for solute transport and biofilm growth in porous media was developed. Compared to previous studies of biofilm growth, it has two new features. First, the constructed pore network gives a better representation of a porous medium. Second, instead of using a constant mass exchange coefficient for solute transport between water phase and biofilm, a variable coefficient as a function of biofilm volume fraction and Damkohler number was employed. This PN model was verified against direction simulations. Then, a number of case studies were conducted, in order to illustrate the temporal evolutions of medium permeability and biomass content under different operating conditions. Finally, we explored the effects of biofilm morphology and permeability on biofilm growth, as well as non-unique relationship between medium permeability reduction and its porosity change.

Highlights

In many natural and engineered porous media, biofilm may present under both saturated and unsaturated conditions
Solute concentrations in the water phase and biofilm are significantly different. This indicates that non-equilibrium mass exchange of solute prevailed in the computational domain
There are two reasons for the concentration discrepancies. It is because narrow regions in the direct simulation were approximated by cylindrical pore throats in the PN modeling

Summary

Introduction

In many natural and engineered porous media, biofilm may present under both saturated and unsaturated conditions. When nutrients are continuously available, biofilm keeps growing on solid walls. This would lead to the condition of bioclogging in porous media (Baveye et al 1998; Pintelon et al 2009). There have been many applications by using biofilm such as biobarriers, microbial-enhanced oil recovery (Afrapoli et al 2011), and bioremediation. Biofilm plays a major role in biological aerated filters for removing carbon and nitrogen (Boltz et al 2010). Biofilm breaks down contaminants into less toxic or non-toxic substances (Cunningham and Mendoza-Sanchez 2006). In subsurface CO2 storage, engineered biofilm is used to plug CO2

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