Bioclogging in porous media: Model development and sensitivity to initial conditions

Abstract

15This work presents a numerical model able to simulate the effect of biomass growth on the hydrau-16 lic properties of saturated porous media, i.e., bioclogging. A new module for an existing coupled 17 flow and reactive-transport code-PHWAT-was implemented. Laboratory experiments were used to 18 validate the model.. Good agreement with the experimental data was found. Model behavior was 19 satisfactory in terms of numerical discretization errors and parameter calibration, although-grid-20 independent results were difficult to achieve. The new code was applied to investigate the effect of 21 the initial conditions on clogging development. A set of simulations was conducted considering 1D 22 and 2D flow conditions, for both uniform and heterogeneous initial biomass concentrations. The 23 simulation results demonstrated that the rate and patterns of bioclogging development are sensitive 24 to the initial biomass distribution. Thus, the common assumption of an initially uniform biomass 25 distribution may not be appropriate and may introduce a significant error in the modeling results. 26

Microbial competition in porous environments can select against rapid biofilm growth

“…Increases in biofilm thickness are countered by the detachment of cells due to mechanical forces exerted at the surface of the biofilm by fluid motion (40) formulation based on the empirical study of ref. 50 is one of the most widely used (45,(51)(52)(53)(54)(55) and has been independently confirmed for biofilms growing in porous media (54,55). Here, the detachment rate is approximated by dk /dt = −χk τ 1/2 , where χ is an empirical parameter with units of length/mass that measures the ability of the biofilm to resist detachment, and τ is the shear stress exerted by the flow on the surface of the biofilm.…”

Influence of hydrodynamics on the growth kinetics of glass-adhering Pseudomonas putida cells through a parallel plate flow chamber

“…Biofilm growth is then modeled through a closure law, whose structure is postulated a priori and often based on Monod kinetics. For instance, Kildsgaard and Engegaard 27 and Brovelli et al 15 made remarkable investigations to study the development and spreading of biofilms in 2D porous media from the early stage. These works were based upon an idea developed by Zysset et al: 28 the biofilm growth rate was modeled by a Monod law (with constant parameters not dependent on flow conditions) modulated by a limitation function in order to take into account mass transfer and biofilm activity limitation as the biofilm becomes thicker.…”

“…In particular mass transfer, which affects directly nutrient availability towards bacterial cells, and then their growth rate, 12 is strongly dependent on flow conditions. 13,14 Yet, the couplings between these local mechanisms are kinetically controlled (time-dependent) 15 and sensitive to initial conditions of surface colonization.…”

Hydraulic conductivity and leachate removal rate of genetically different compacted clays

“…Observed changes in HC could be related to expansion/ shrinkage of expansive minerals, mineral clogging, and bioactivity [30]. Leachate reduced the HC of SMP 1 and [23] is attributable to the bioactivity of the leachate, causing pore clogging while in addition, a slight consolidation of the soil sample and small reduction of the void ratio also leads to decreased HC [14]. Nutrients load, present in leachates, is responsible for increased formation and development of bacteria and yeast colonies resulting in partial or permanent soil pore blocking [30,61] which might have resulted in low permeability of the soils by a larger diffused double layer (DDL) effect in the soil structure.…”