On multicomponent gas diffusion and coupling concepts for porous media and free flow: a benchmark study

Ahmadi, Navid; Heck, Katharina; Rolle, Massimo; Helmig, Rainer; Mosthaf, Klaus

doi:10.1007/s10596-021-10057-y

Cited by 15 publications

(4 citation statements)

References 64 publications

(66 reference statements)

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“…It is reported that the pressure is sensitive to variations of wind speed when the speed is above an certain value (e.g., 3 m/s) (Chi et al 2013 ; Laemmel et al 2017 ).The pressure differential may have a range from -0.1 kPa to 0.1 kPa (Gebert et al 2011 ; Redeker et al 2015 ). It should be noted that fluctuations of wind speed may also affect gas transport process from the cover soil to the air and mixing in the headspace (Ahmadi et al, 2021 ), which was not assessed in this study.…”

Section: Resultsmentioning

confidence: 93%

Numerical model for static chamber measurement of multi-component landfill gas emissions and its application

Xie

Zuo

Chen

et al. 2022

Environ Sci Pollut Res

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The quantitative assessment of landfill gas emissions is essential to assess the performance of the landfill cover and gas collection system. The relative error of the measured surface emission of landfill gas may be induced by the static flux chamber technique. This study aims to quantify effects of the size of the chamber, the insertion depth, pressure differential on the relative errors by using an integrated approach of in situ tests, and numerical modeling. A field experiment study of landfill gas emission is conducted by using a static chamber at one landfill site in Xi’an, Northwest China. Additionally, a two-dimensional axisymmetric numerical model for multi-component gas transport in the soil and the static chamber is developed based on the dusty-gas model (DGM). The proposed model is validated by the field data obtained in this study and a set of experimental data in the literature. The results show that DGM model has a better capacity to predict gas transport under a wider range of permeability compared to Blanc’s method. This is due to the fact that DGM model can explain the interaction among gases (e.g., CH4, CO2, O2, and N2) and the Knudsen diffusion process while these mechanisms are not included in Blanc’s model. Increasing the size and the insertion depth of static chambers can reduce the relative error for the flux of CH4 and CO2. For example, increasing the height of chambers from 0.55 to 1.1 m can decrease relative errors of CH4 and CO2 flux by 17% and 18%, respectively. Moreover, we find that gas emission fluxes for the case with positive pressure differential (∆Pin-out) are greater than that of the case without considering pressure fluctuations. The Monte Carlo method was adopted to carry out the statistical analysis for quantifying the range of relative errors. The agreement of the measured field data and predicted results demonstrated that the proposed model has the capacity to quantify the emission of landfill gas from the landfill cover systems.

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Section: Resultsmentioning

confidence: 93%

Numerical model for static chamber measurement of multi-component landfill gas emissions and its application

Xie

Zuo

Chen

et al. 2022

Environ Sci Pollut Res

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“…The results of this study are of interest for natural fate and transport of geogenic contaminants in groundwater, as well as at the interface between different environmental compartments (e.g., surface/groundwater) where the exchange of atmospheric oxygen and its mixing with anoxic pore water can trigger different biogeochemical reactions. − The outcomes of this investigation may help designing MAR strategies that minimize the oxidative dissolution of sulfide minerals and the release of arsenic. As an example, infiltration and/or injection rates could be adequately chosen to favor the retention of arsenic in solid phases, thus limiting the risk of freshwater contamination during MAR.…”

Section: Results and Discussionmentioning

confidence: 95%

Oxidative Dissolution of Arsenic-Bearing Sulfide Minerals in Groundwater: Impact of Hydrochemical and Hydrodynamic Conditions on Arsenic Release and Surface Evolution

Stolze

Battistel

Rolle

2022

Environ. Sci. Technol.

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The dissolution of sulfide minerals can lead to hazardous arsenic levels in groundwater. This study investigates the oxidative dissolution of natural As-bearing sulfide minerals and the related release of arsenic under flow-through conditions. Column experiments were performed using reactive As-bearing sulfide minerals (arsenopyrite and lollingite) embedded in a sandy matrix and injecting oxic solutions into the initially anoxic porous media to trigger the mineral dissolution. Noninvasive oxygen measurements, analyses of ionic species at the outlet, and scanning electron microscopy allowed tracking the propagation of the oxidative dissolution fronts, the mineral dissolution progress, and the change in mineral surface composition. Process-based reactive transport simulations were performed to quantitatively interpret the geochemical processes. The experimental and modeling outcomes show that porewater acidity exerts a key control on the dissolution of sulfide minerals and arsenic release since it determines the precipitation of secondary mineral phases causing the sequestration of arsenic and the passivation of the reactive mineral surfaces. The impact of surface passivation strongly depends on the flow velocity and on the spatial distribution of the reactive minerals. These results highlight the fundamental interplay of reactive mineral distribution and hydrochemical and hydrodynamic conditions on the mobilization of arsenic from sulfide minerals in flow-through systems.

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“…Here, the species diffusion is described by Fick's law. More sophisticated models such as Maxwell‐Stefan equations can be used to model the multicomponent diffusion (Ahmadi et al., 2021).…”

Section: Micro‐continuum Models For Coupled Processesmentioning

confidence: 99%

Micro‐Continuum Modeling: An Hybrid‐Scale Approach for Solving Coupled Processes in Porous Media

Soulaine

2024

Water Resources Research

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Micro‐continuum models are versatile and powerful approaches for simulating coupled processes in two‐scale porous systems. Initially oriented for modeling static single‐phase flow in microtomography images with sub‐voxel porosity, the concept has been extended over the years to multi‐phase flow, reactive transport, and poromechanics. This paper introduces an integrated micro‐continuum framework to model coupled processes in porous media. It reviews state‐of‐the‐art models and discusses applications in geosciences including Digital Rock Physics with sub‐voxel porosity, moving fluid‐solid interface at the pore‐scale due to geochemical reactions, fracture‐matrix interactions, and solid deformation. Finally, the paper discusses future developments in micro‐continuum models.

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On multicomponent gas diffusion and coupling concepts for porous media and free flow: a benchmark study

Cited by 15 publications

References 64 publications

Numerical model for static chamber measurement of multi-component landfill gas emissions and its application

Numerical model for static chamber measurement of multi-component landfill gas emissions and its application

Oxidative Dissolution of Arsenic-Bearing Sulfide Minerals in Groundwater: Impact of Hydrochemical and Hydrodynamic Conditions on Arsenic Release and Surface Evolution

Micro‐Continuum Modeling: An Hybrid‐Scale Approach for Solving Coupled Processes in Porous Media

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