MiBiReMo - Examples

Currently, three examples are available. To run the examples, navigate to the examples directory and run the desired example script:

cd path/to/project_folder
source mibiremo/bin/activate
cd path/to/mibiremo_source/examples
python ex1-titration.py

Example 1 - Titration

The first example ex1-titration.py demonstrates the use of the package to simulate a simple titration in a batch, where a solution is equilibrated with a mineral phase (calcite) and the pH is adjusted by adding HCl.

Example 2 - Benzene and Ethylbenzene kinetic dissolution

The second example ex2-BTEX_dissolution.py demonstrates the use of the package to simulate the kinetic dissolution of benzene and ethylbenzene in a batch reactor.

Example 3 - Reactive transport - BTEX dissolution and transport

The third example ex3-BTEX_dissolution_transport_coupling.py demonstrates the use of the package to simulate the reactive transport of benzene and ethylbenzene in a 1D domain. The problem is described in the following scheme:

The model consists of a 1D domain with a length of 50 m. The domain is initially filled with clean groundwater with a spot of benzene and ethylbenzene pure phases present at the left side of the domain extending for 0.5 m. We assumed that the contaminant pure phase in the source zone is immobile (it only dissolves). The groundwater flows from left to right with a velocity of 1 m/d, and dissolved benzene and ethylbenzene are transported towards the right end of the domain. The dissolution process is modelled both kinetically and equilibrium-based. The model is run for 100 days, and the concentration of benzene and ethylbenzene is monitored at the right side of the domain.

Three simulation runs are performed: 1. Equilibrium dissolution of benzene and ethylbenzene simulated with PHREEQC (standalone). 2. Equilibrium dissolution of benzene and ethylbenzene simulated by MiBiReMo (1D transport solver coupled with PhreeqcRM). 3. Kinetic dissolution of benzene and ethylbenzene simulated by MiBiReMo.

The transport equition (advection and dispersion) in MiBiReMo is solved using a Semi-Lagrangian scheme with operator splitting, where the advection is solved using the method of characteristics with cubic spline interpolation, and the dispersion is solved using the Saul’yev finite differences technique.

Simulation results are shown in the following figure:

The results obtaines show a pattern similar to the experimental results obtained by Geller and Hunt (1993) [1]. In their experiment they injected an equimolar mixture of benzene and toluene in the center of a column which was subsequently eluted with water. The results show that benzene is eluted first, followed by toluene because of the different solubilities. The following figure shows the experimental results obtained by Geller and Hunt (1993):

References

[1] Geller, J. T., and J. R. Hunt (1993), Mass transfer from nonaqueous phase organic liquids in water-saturated porous media, Water Resour. Res., 29(4), 833–845, doi:10.1029/92WR02581.