Modelling species fate and porous media effects for landfill leachate flow

2005 ◽  
Vol 42 (4) ◽  
pp. 1116-1132 ◽  
Author(s):  
A J Cooke ◽  
R K Rowe ◽  
B E Rittmann
Keyword(s):  
Porous Media ◽  
Landfill Leachate ◽  
Reactive Transport ◽  
Volatile Fatty Acids ◽  
Transport Model ◽  
Calcium Carbonate Precipitation ◽  
Transport Modelling ◽  
Inorganic Particles ◽  
The Media ◽  
Multiple Species

A numerical, multiple-species, reactive transport model, coupled to models of kinetic biodegradation, precipitation, and particle attachment and detachment for predicting landfill leachate-induced clogging in porous media for one-dimensional flow systems, is described. The finite-element method is used for transport modelling, with reactions incorporated into point-source or sink terms. The species modelled include three volatile fatty acids, active and inert suspended biomass, dissolved calcium, and inorganic particles. The clog matter consists of active biofilm, inert biofilm, and inorganic solids. A biofilm model is used to simulate the growth and decay of active biomass and removal of substrate. Precipitate accumulation and calcium removal are simulated by a model of calcium carbonate precipitation. Interphase movement between clog matter and fluid includes the processes of attachment and detachment. A geometric representation of the porous media allows porosity and specific surface to be estimated from the thickness of the accumulated clog matter. The porosity of the media can thus change spatially and temporally. The behaviour of the model is demonstrated with a hypothetical example.Key words: clogging, landfills, leachate collection systems, modelling, biofilms, mineral precipitation.

2D modelling of clogging in landfill leachate collection systems

2008 ◽  
Vol 45 (10) ◽  
pp. 1393-1409 ◽  
Author(s):  
A. J. Cooke ◽  
R. Kerry Rowe
Keyword(s):  
Finite Element ◽  
Hydraulic Conductivity ◽  
Landfill Leachate ◽  
Transport Model ◽  
Point Sources ◽  
Time Step ◽  
Leachate Collection ◽  
Aspect Ratios ◽  
The Media ◽  
Multiple Species

A 2D model for predicting clogging of a landfill leachate collection system and subsequent leachate surface position (mounding) is described. A transient finite element fluid flow model is combined with a reactive, multiple-species finite element transport model. The transport model considers biological growth and biodegradation, precipitation, and particle attachment and detachment. It uses a geometrical relationship to establish porosity from the computed thickness of the accumulated clog matter and a relationship between the porosity and hydraulic conductivity of elements in the system. The model represents the flow path within the drainage layer in profile. An iterative method is used to solve for the new hydraulic heads, surface and internal nodal positions, and redistributed clog properties (clog quantity, porosity, hydraulic conductivity) for each element and for each time step. The porosity (and consequently hydraulic conductivity) of the media can therefore change spatially and temporally. The mesh is regenerated automatically each time step (including the addition or subtraction of nodes) taking into account allowable element aspect ratios, the interfaces between differing hydrostratigraphic layers, and static point sources and openings. An integrated alternate solution for very thin mounds is included. The application of the model is demonstrated using a hypothetical field case.

Application of the BioClog model for landfill leachate clogging of gravel-packed columns

2005 ◽  
Vol 42 (6) ◽  
pp. 1600-1614 ◽  
Author(s):  
A J Cooke ◽  
R K Rowe ◽  
J VanGulck ◽  
B E Rittmann
Keyword(s):  
Landfill Leachate ◽  
Volatile Fatty Acids ◽  
Transport Model ◽  
Packed Columns ◽  
Chemical Transport Model ◽  
Inorganic Solids ◽  
Leachate Collection ◽  
Suspended Biomass ◽  
Reactive Chemical Transport ◽  
Multiple Species

A numerical, multiple-species, reactive chemical transport model (BioClog) developed to predict clogging in landfill leachate collection systems is used to interpret results from experiments conducted with gravel-packed columns permeated with landfill leachate. The model predicts changes to the microbial community and leachate chemistry, including the concentrations of volatile fatty acids, suspended biomass, dissolved calcium, and suspended inorganic solids. The calculated quantity and composition of the clog matter (biomass and mineral), along with the associated decrease in porosity, are compared to the measured values. The modelled clogging is in reasonable agreement with that observed in the gravel column experiments. By identifying and quantitatively linking many microbiological, chemical, and transport mechanisms, the model helps elucidate the phenomena controlling the rate and extent of clogging.Key words: clogging, landfills, leachate collection systems, biofilms, mineral precipitation.

scholarly journals Combination of MRI and SEM to Assess Changes in the Chemical Properties and Permeability of Porous Media due to Barite Precipitation

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 226 ◽  
Author(s):  
Jenna Poonoosamy ◽  
Sabina Haber-Pohlmeier ◽  
Hang Deng ◽  
Guido Deissmann ◽  
Martina Klinkenberg ◽  
...  
Keyword(s):  
Porous Media ◽  
Magnetic Resonance ◽  
Reactive Transport ◽  
Relaxation Times ◽  
Chemical Properties ◽  
Column Experiment ◽  
Transverse Relaxation Time ◽  
Gas Production ◽  
Transport Modelling ◽  
Transverse Relaxation

The understanding of the dissolution and precipitation of minerals and its impact on the transport of fluids in porous media is essential for various subsurface applications, including shale gas production using hydraulic fracturing (“fracking”), CO2 sequestration, or geothermal energy extraction. In this work, we conducted a flow through column experiment to investigate the effect of barite precipitation following the dissolution of celestine and consequential permeability changes. These processes were assessed by a combination of 3D non-invasive magnetic resonance imaging, scanning electron microscopy, and conventional permeability measurements. The formation of barite overgrowths on the surface of celestine manifested in a reduced transverse relaxation time due to its higher magnetic susceptibility compared to the original celestine. Two empirical nuclear magnetic resonance (NMR) porosity–permeability relations could successfully predict the observed changes in permeability by the change in the transverse relaxation times and porosity. Based on the observation that the advancement of the reaction front follows the square root of time, and micro-continuum reactive transport modelling of the solid/fluid interface, it can be inferred that the mineral overgrowth is porous and allows the diffusion of solutes, thus affecting the mineral reactivity in the system. Our current investigation indicates that the porosity of the newly formed precipitate and consequently its diffusion properties depend on the supersaturation in solution that prevails during precipitation.

scholarly journals Joint Estimation of Hydraulic and Biochemical Parameters for Reactive Transport Modelling with a Modified ILUES Algorithm

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2161
Author(s):  
Ruicheng Zhang ◽  
Nianqing Zhou ◽  
Xuemin Xia ◽  
Guoxian Zhao ◽  
Simin Jiang
Keyword(s):  
Reactive Transport ◽  
Biochemical Parameters ◽  
Transport Model ◽  
Joint Estimation ◽  
Model Parameters ◽  
Transport Modelling ◽  
Selection Scheme ◽  
Related Model ◽  
Ensemble Smoother ◽  
Iterative Ensemble Smoother

Multicomponent reactive transport modeling is a powerful tool for the comprehensive analysis of coupled hydraulic and biochemical processes. The performance of the simulation model depends on the accuracy of related model parameters whose values are usually difficult to determine from direct measurements. In this situation, estimates of these uncertain parameters can be obtained by solving inverse problems. In this study, an efficient data assimilation method, the iterative local updating ensemble smoother (ILUES), is employed for the joint estimation of hydraulic parameters, biochemical parameters and contaminant source characteristics in the sequential biodegradation process of tetrachloroethene (PCE). In the framework of the ILUES algorithm, parameter estimation is realized by updating local ensemble with the iterative ensemble smoother (IES). To better explore the parameter space, the original ILUES algorithm is modified by determining the local ensemble partly with a linear ranking selection scheme. Numerical case studies based on the sequential biodegradation of PCE are then used to evaluate the performance of the ILUES algorithm. The results show that the ILUES algorithm is able to achieve an accurate joint estimation of related model parameters in the reactive transport model.

scholarly journals The Tournemire industrial analogue: reactive-transport modelling of a cement–clay interface

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 167-184 ◽  
Author(s):  
C. Watson ◽  
D. Savage ◽  
J. Wilson ◽  
S. Benbow ◽  
C. Walker ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Reactive Transport ◽  
Transport Model ◽  
Surface Complexation ◽  
General Purpose ◽  
Transport Modelling ◽  
Mineralogical Characterization ◽  
Modelling Techniques ◽  
Materials Used ◽  
Set Up

AbstractIn the post-closure period of a geological disposal facility for radioactive waste, leaching of cement components is likely to give rise to an alkaline plume which will be in chemical disequilibrium with the host rock (which is clay in some concepts) and other engineered barrier system materials used in the facility, such as bentonite. An industrial analogue for cement-clay interaction can be found at Tournemire, southern France, where boreholes filled with concrete and cement remained in contact with the natural mudstone for 15–20 years. The boreholes have been overcored, extracted and mineralogical characterization has been performed. In this study, a reactive-transport model of the Tournemire system has been set up using the general-purpose modelling tool QPAC. Previous modelling work has been built upon by using the most up-to-date data and modelling techniques, and by adding both ion exchange and surface complexation processes in the mudstone. The main features observed at Tournemire were replicated by the model, including porosity variations and precipitation of carbonates, K-feldspar, ettringite and calcite. It was found that ion exchange needed to be included in order for C-S-H minerals to precipitate in the mudstone, providing a better match with the mineralogical characterization. The additional inclusion of surface complexation, however, led to limited calcite growth at the concrete-mudstone interface unlike samples taken from the Tournemire site that have a visible line of crusty carbonates along the interface.

PHT3D-UZF: A Reactive Transport Model for Variably-Saturated Porous Media

Ground Water ◽  
2015 ◽  
Vol 54 (1) ◽  
pp. 23-34 ◽  
Author(s):  
Ming Zhi Wu ◽  
Vincent E.A. Post ◽  
S. Ursula Salmon ◽  
Eric D. Morway ◽  
Henning Prommer
Keyword(s):  
Porous Media ◽  
Reactive Transport ◽  
Transport Model ◽  
Saturated Porous Media ◽  
Reactive Transport Model

scholarly journals Trace element mobility during CO2 storage: application of reactive transport modelling

2019 ◽  
Vol 98 ◽  
pp. 04007
Author(s):  
Dirk Kirste ◽  
Julie K. Pearce ◽  
Sue D. Golding ◽  
Grant K.W. Dawson
Keyword(s):  
Water Quality ◽  
Chemical Composition ◽  
Reactive Transport ◽  
Transport Model ◽  
Co2 Storage ◽  
Chemical Components ◽  
Transport Modelling ◽  
Geochemical Model ◽  
Trace Element Mobility ◽  
The Individual

The geologic storage of CO2 carries both physical and chemical risks to the environment. In order to reduce those risks, it is necessary to provide predictive capabilities for impacts so that strategies can be developed to monitor, identify and mitigate potential problems. One area of concern is related to water quality both in the reservoir and in overlying aquifers. In this study we report the critical steps required to develop chemically constrained reactive transport models (RTM) that can be used to address risk assessment associated with water quality. The data required to produce the RTM includes identifying the individual hydrostratigraphic units and defining the mineral and chemical composition to sufficient detail for the modelling. This includes detailed mineralogy, bulk chemical composition, reactive mineral phase chemical composition and the identification of the occurrence and mechanisms of mobilisation of any trace elements of interest. Once the required detail is achieved the next step involves conducting experiments to determine the evolution of water chemistry as reaction proceeds preferably under varying elevated CO2 fugacities with and without impurities. Geochemical modelling of the experiments is then used for characterising the reaction pathways of the different hydrostratigraphic units. The resultant geochemical model inputs can then be used to develop the chemical components of a reactive transport model.

Modelling landfill leachate-induced clogging of field-scale test cells (mesocosms)

2008 ◽  
Vol 45 (11) ◽  
pp. 1497-1513 ◽  
Author(s):  
Andrew J. Cooke ◽  
R. Kerry Rowe
Keyword(s):  
Landfill Leachate ◽  
Reactive Transport ◽  
Transport Model ◽  
Empirical Relationship ◽  
Oxygen Demand ◽  
Reactive Transport Model ◽  
Variable Mesh ◽  
Scale Test ◽  
Real Scale ◽  
Mesh Technique

A two-dimensional fluid flow and reactive transport model, BioClog, created to predict clogging in landfill leachate collection systems is used to calculate the clogging of gravel and treatment of leachate as it flows through the gravel in two real-scale experimental cells, called mesocosms, which represent the portion of a landfill drainage layer adjacent to a landfill collection pipe. These tests were conducted using real-time flows of landfill leachate and were run for about 6 and 12 years. The model computes spatial and temporal changes in clog quantity and composition. An empirical relationship predicts changes in hydraulic conductivity, and a variable mesh technique allows the surface to be free and dependent on calculated hydraulic heads. Calculated porosity change, effluent chemical oxygen demand (COD), and calcium concentrations, along with porosity and clog film thickness at termination are compared with the observed values and found to be in reasonable agreement given the variability and uncertainties associated with these processes.

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