Numerical modeling of biogeobattery system from microbial degradation of underground organic contaminant

Abstract

Redox fields observed near contaminated sites are related to electrochemical and electrobiological reactions. The term biogeobattery is used to describe the redox processes in underground organic contaminated sites which are biogeochemical systems, where bacteria, conductive minerals, oxygen, and organic contaminants create numerous anode-cathode pairs by transferring electrons from reducing areas under the water table or other anaerobic conditions to oxidizing areas above the water table. A numerical biogeobattery model established based on the geobattery and inert electrode model is the theoretical basis for numerical modeling. A coupled method of tetrahedral finite elements and hexahedral infinite elements is proposed for the algorithm basis of numerical modeling. Then a small-scale biogeochemical system and a field-scale landfill system are modeled using the numerical biogeobattery model and the finite-infinite element coupling method. The results suggest that the accuracy of the coupled method is superior to the finite element method. The amplitude change in the embedded redox field has a great effect on self-potential anomalies, while the gradient change in the embedded redox field has no significant impact on self-potential anomalies. The resolution of the surface self-potential decreases with the depth of biogeochemical systems. The biogeobattery model based on the inert electrode model is an effective numerical model in biogeochemical systems.

Redox Potentials of Magnetite Suspensions under Reducing Conditions

“…Iron (Fe) oxides are ubiquitous in soils and sediments and play critical roles in contaminant remediation in the environment, biological respiration, and nutrient cycling. − Fe oxides are redox active and cycle between ferrous and ferric Fe, releasing aqueous Fe­(II) into the subsurface that substantially affects subsurface geochemistry. , Magnetite, a mixed valent Fe­(II)/Fe­(III) mineral, forms in soils and sediments under reducing conditions and has been shown to reduce several contaminants. − ,− Magnetite’s ability to store and release charge during microbial respiration, contaminant remediation, and nutrient cycling has been highlighted as a potential biogeobattery in the environment. ,, Because of its high conductivity, magnetite also has broad uses in industrial and technological materials and processes, such as nanofuels, capacitors, and batteries. ,− Magnetite redox properties have been widely explored for these applications, as well as their role in natural and engineered environments relevant to contaminant behavior. ,,,− …”

“… 3 − 5 , 13 − 25 Magnetite’s ability to store and release charge during microbial respiration, contaminant remediation, and nutrient cycling has been highlighted as a potential biogeobattery in the environment. 10 , 26 , 27 Because of its high conductivity, magnetite also has broad uses in industrial and technological materials and processes, such as nanofuels, capacitors, and batteries. 3 , 28 − 30 Magnetite redox properties have been widely explored for these applications, as well as their role in natural and engineered environments relevant to contaminant behavior.…”

Formulas and Results

“…The forward methods commonly used for self-potential methods include numerical solutions and analytical solutions. The numerical solution is a qualitative (or semi-quantitative) technique (Wei et al, 2023), which includes the finite element method (Alarouj and Jackson, 2022;Bérubé, 2007), the finite volume method (Sheffer and Oldenburg, 2007), the finite difference method (Xie et al, 2020a), the natural-infinite element coupling method (Xie et al, 2020b), the finite-infinite element coupling method (Xie et al, 2020c)and so on. Numerical modeling applies to any complex model.…”

Three-Dimensional Analytical Solution of Self-potential from Regularly Polarized Bodies in Layered Seafloor Model

“…The forward methods commonly used for self-potential methods include numerical solutions and analytical solutions. The numerical solution is a qualitative (or semi-quantitative) technique (Wei et al, 2023), which includes the finite element method (Alarouj and Jackson, 2022;Bérubé, 2007), the finite volume method (Sheffer and Oldenburg, 2007), the finite difference method (Xie et al, 2020a), the natural-infinite element coupling method (Xie et al, 2020b), the finite-infinite element coupling method (Xie et al, 2020c)and so on. Numerical modeling applies to any complex model.…”