Using particle tracking to simulate contaminant transport in the presence of colloids and bacteria

Autor: Ahmed E. Hassan, Mohamed A. Abd-Elmegeed, Ahmed M. Hedia
Rok vydání: 2021
Předmět:
Zdroj: Arabian Journal of Geosciences. 14
ISSN: 1866-7538
1866-7511
DOI: 10.1007/s12517-021-08306-6
Popis: The presence of colloids and bacteria in groundwater affects contaminant migration either by facilitation or retardation. The co-transport of contaminant and colloidal particles had been simulated using various finite difference schemes which may suffer from the known and common numerical dispersion problem. In this study, a random walk particle tracking (RWPT) scheme is developed to simulate the co-transport of contaminants, colloids, and bacteria in porous media. Processes modeled include colloidal deposition to and release from solid matrix, bacterial attachment to and detachment from solid matrix, and contaminant sorption onto and desorption from mobile and immobile colloidal particles and bacterial cells as well as solid matrix. Also, the biological processes between contaminant and bacterial cells including bacterial growth, decay, and contaminant utilization are simulated. The developed model is verified against MT3D-MS for reactive contaminant transport with solid matrix, and reaction processes have been verified with solution of a developed analytical solution of mass balance equations. The biological processes are incorporated into the developed RWPT model which is verified against TVD finite difference model developed by (El-Kordy 2008). The results show good performance of RWPT technique in simulating contaminant transport in the presence of colloids and bacteria. The effects of various physical and biological parameters on contaminant transport are investigated. The results show that at least 50,000 particles are required to simulate each constituent mass in case of consideration of biological processes in contaminant transport simulation. On the other hand, 10,000 particles are found to be sufficient to simulate each constituent mass for case of contaminant transport undergoing physical and chemical processes only. The results indicate that contaminant utilization increases by increasing the ratio of initial concentrations of bacterial cells and contaminant, the ratio of the half-saturation constant to initial contaminant concentration, and the ratio of the maximum growth rate to the yield coefficient. It is also found from the results that higher contaminant utilization occurs at early time and decreases as time progresses.
Databáze: OpenAIRE
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