A generic transport-reactive model for simulating microbially influenced mineral precipitation in porous medium

A generic transport-reactive model for simulating microbially influenced mineral precipitation in porous medium

Zhou, J.
Van Turnhout, A.G.
Heimovaara, T.J.
Afanasyev, M.

Civil Engineering and Geosciences

Geoscience & Engineering

2015-04-14

The spatial and temporal distribution of precipitated minerals is one of the key factors governing various processes in the sub-surface environment, including microbially influenced corrosion (MIC) (Huang, 2002), bio-cementation (van Paassen et al., 2010) and sediment diagenesis (Paraska et al., 2014). The mineral precipitation not only affects the overall reaction network (Konhauser, 1997), but is also physically interconnected with the transport properties of the subsurface environment (Pintelon et al., 2012). The presence of bacteria in the subsurface greatly influences the processes of mineral precipitation (Konhauser, 1997). We apply mathematical modeling to investigate the microbially influenced mineral precipitation process under various environmental conditions. The boundary concentrations of different solutes and the distance between the boundaries are considered to have a dominant effect on the magnitude and position and width of precipitated minerals (Gebrehiwet et al., 2014). We study the mineral precipitation induced by MIC, a process that can be interpreted as a double diffusion mixing mineral precipitation process as shown in figure 1.1. The occurrence of biocorrosion releases metallic ion from the metal surface and creates a concentration gradient of metallic ions towards the reaction region. Released metallic ions react with existing anions, for instance carbonate, and induce a concentration gradient of anions from the distant boundary to the reaction region. The concentrations of anions at the distant boundary is continuously recharged by groundwater. Meanwhile, the concentration of metallic ions at the metal surface is maintained by the metal corrosion. The concentration gradients lead to molecular diffusion from both metal surface and distant boundary towards the reaction region, and result in mineral precipitation. Two functions of bacteria are distinguished in MIC induced mineral preciptiation: influence of biocorrosion and formation of biomass. The effects of bacteria in the double diffusion configuration are implicitly included in the iron corrosion boundary, and the biomass formation is explicitly employed in the reaction region as shown in Figure 1.1. In terms of unlined landfills, the leakage of inorganic and organic pollutants can be interpreted as a diffusion boundary while the recharge of groundwater is treated as the other diffusion boundary. Similarly, the same double diffusion configuration can be applied to investigate the landfill leachate related mineral precipitation with the inclusion of microbial activities. The removal of heavy metals via mineral precipitation, on the one hand, helps to purify the contaminated groundwater and soil; on the other hand, the solid mass accumulation can be served as a clogging mechanism to reduce the leachate flow. With the aid of our model, we obtain a more comprehensive insight into the relations between the development of microbially influenced mineral precipitation and the environment conditions.

http://resolver.tudelft.nl/uuid:9a20255e-d3d5-487b-b433-cec4b6a0ba0f

HPM6: The 6th International Workshop Hydro-Physico-Mechanics of Landfills, Delft, The Netherlands, 14-17 April 2015

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