Analysis Of Contaminant Transport Research Articles

Analysis of Chloride Contaminant Transport in Tailings Storage Facility Dam (Case Study: Gold Mine in Sumatra)

In the practice of gold mining industry, hazardous waste known as tailings is produced during the ore extraction process. These tailings are typically stored in a dam structure called a Tailings Storage Facility (TSF). The planning and construction of a TSF are critical considerations, as the failure of a TSF can have substantial environmental impacts, pose risks to human safety, and result in industrial losses. Therefore, strict control is necessary in the development of TSFs to minimize the potential negative consequences. This research focuses on the transport of contaminants within a TSF, specifically examining the concentration of chloride contaminants and conducting particle movement analysis. The study utilizes modeling through the GeoStudio SEEP/W program to simulate groundwater flow profiles and the GeoStudio CTRAN/W program to understand contaminant movement over a 100-year period. GeoStudio modeling employs 10 materials: impermeable clay soil, filter sandy soil, transition gravel rock, three mine waste types (Fine, Rockfill, and Rockfill with fine), hard rock bedrock layer, in-situ soil representing the original layer, landslide with colluvial soil, and the tailings itself. Back analysis is employed to iterate model parameters and ensure modeling accuracy against field data, including comparisons with water quality test results and readings from vibrating wire piezometer (VWP) instrumentation. The contaminant transport is influenced by advection-dispersion processes and tends to concentrate within the TSF boundary toward the dam toe over a 100-year timeframe. The analysis emphasizes the influence of advection in contaminant transport and underscores the importance of particle position relative to the groundwater level, with Particle Tracking Analysis shows significant movement within the groundwater flow area. This research provides crucial insights into the dynamics of contaminant concentration, informing better decision-making in TSF planning and management. The findings underscore the imperative of strict control measures to minimize environmental impacts and human safety risks associated with TSFs, thereby advancing knowledge in gold mining waste management.

Case Study of Contaminant Transport Using Lagrangian Particle Tracking Model in a Macro-Tidal Estuary

This study presents a comprehensive analysis of contaminant transport in estuarine environments, focusing on the impact of tidal creeks and flats. The research employs advanced hydrodynamic models with irregular grid systems and conducts a detailed residual current analysis to explore how these physical features influence the movement and dispersion of contaminants. The methodology involves simulating residual currents and Lagrangian particle trajectories in both ‘Creek’ and ‘No Creek’ cases, under varying tidal conditions. The results indicate that tidal creeks significantly affect particle retention and transport, with notable differences observed in the dispersion patterns between the two scenarios. The ‘Creek’ case demonstrates enhanced material retention along the creek pathways, while the ‘No Creek’ case shows broader dispersion, potentially leading to increased sedimentation in open sea areas. The discussion highlights the implications of these findings for sediment dynamics, contaminant transport, and estuarine ecology, emphasizing the role of tidal creeks in modulating flow and material transport. The research underlines the necessity of incorporating detailed environmental features in estuarine models for accurate contaminant transport prediction and effective estuarine management. This study contributes to a deeper understanding of estuarine hydrodynamics and offers valuable insights for environmental policy and management in coastal regions.

The Remediation of Congo Red-Contaminated Groundwater by using a Permeable Reactive Barrier Through Modified Waterworks Sludge MgAl-LDH

This investigation aims to explore the potential of waterworks sludge (WS), low-cost byproduct of water treatment processes, as a sorbent for removing Congo Red (CR) dyes. This will be achieved by precipitating nano-sized (MgAl-LDH)-layered double hydroxide onto the surface of the sludge. The efficiency of utilizing MgAl-LDH to modify waterworks sludge (MWS) for use in permeable reactive barrier technology was confirmed through analysis with Fourier transform infrared and X-ray diffraction. The isotherm model was employed to elucidate the adsorption mechanisms involved in the process. Furthermore, the COMSOL model was utilized to establish a continuous testing model for the analysis of contaminant transport under diverse conditions. A strong correlation was indicated, with a coefficient of determination (R2) ≥ 0.97, when the model's predictions were compared to experimental values, indicating the accuracy of the model. Continuous transport exhibited earlier breakthrough points when the bed depth decreased and the initial concentration and flow rate increased.

Subsurface Contaminant Transport Analysis for Flowpath Direction in Katni Watershed, Madhya Pradesh, India Using GIS and Groundwater Modeling Approach

The current study aims to identify the pathways of pollutants and travel time of contamination using Remote Sensing and GIS approach. In sight of this, to evaluate hazard, groundwater contaminant transport is analyzed by using the ground water model in Katni River watershed. Darcy flow and velocity have been used for contaminant transport analysis, which is one of the components of Arc GIS in Groundwater module extension. Modeling tools such as Kriging, Darcy Flow/Velocity and Linear Directional Mean were used to identify the groundwater path lines and travel time. The analysis was done by taking into account of vulnerable areas, the location of contaminant sources and infected wells and their well field. The hydro-geological properties of underlying rocks along with surface and groundwater elevation are also considered by simulations, found that flow lines intersect with the Katni River in numerous places and flow lines converge towards wells in the study area, implying contaminated water is carried to these areas from all directions. Consequentially, the quality of the surface and groundwater is determining the quality of water in the wells Keywords: Contaminant Transport Analysis, Pathways and Travel Time, Groundwater Flow Model, Darcy Flow, GIS, Kriging

Contaminant transport analysis under non-linear sorption in a heterogeneous groundwater system

ABSTRACT In this study, a one-dimensional non-linear advection–dispersion equation subject to spatial–temporal dependent advection and dispersion coefficients is solved for a heterogeneous groundwater system. The non-linearity of the governing equation is based on the Freundlich and Langmuir sorption isotherms. The groundwater flow is considered to vary exponentially with time. Also, a generalized theory of the dispersion coefficient is used for extensive study of the model problem. The approximate solutions of the model problem are obtained in a semi-infinite and finite heterogeneous media by employing the Crank–Nicolson scheme. The exact solutions are obtained in both domains by the Laplace transform technique subject to linear sorption isotherm and non-transient flow conditions. Further, various graphical solutions are obtained using MATLAB scripts to examine the contaminant transport behaviour. For quantitative evaluation of the proposed model, a root mean square (RMS) error is computed. Overall, the results show that RMS error of the approximate solutions with respect to the exact solutions is within acceptable limits (less than 5%) for different combinations of discretization parameters. The robustness of the proposed model suggests its better suitability for modelling groundwater transport phenomena under the consideration of a non-linear sorption isotherm.

Effects of Using Air Curtains on Energy Consumption During Cooling Season Under Different Climate Conditions

In zones separated by doors with many entrances and exits, it is crucial in terms of energy consumption to protect the conditioned air in the indoor environment from the effects of outside air. The increase in door dimensions and opening frequency make this effect even more evident. Various methods are used to prevent leakage of outside air into the indoor environment. In this study, we investigated the effects of using air curtains on energy consumption during the cooling season in a factory building. The door width and height in this building, which has a high story height, were also large. These 26 doors must remain open all the time because of the production process. With a transient model developed on Transient System Simulation Tool (TRNSYS) coupled with Contaminant Transport Analysis Software (CONTAM), we showed the effects of using the air curtains in different climate conditions. As a result, we demonstrated that using air curtains will provide great savings, especially in cities with high cooling requirements.

On the Benefits of Whole-building IAQ, Ventilation, Infiltration, and Energy Analysis Using Co-simulation between CONTAM and EnergyPlus

Publicly available tools to perform whole-building simulation of indoor air quality, ventilation, and energy have been available for several decades. Until recently, these tools were developed in isolation, such as the whole-building contaminant transport and airflow analysis tool, CONTAM, developed by the National Institute of Standards and Technology (NIST) and the whole-building energy analysis tool, EnergyPlus, developed by the U.S. Department of Energy (DOE). The ability to couple these tools during runtime has been implemented through co-simulation, enabling improved analysis of the interdependent effects of temperature and airflow on contaminant transport and energy use on a whole-building scale.This presentation will include the development of a set of coupled reference building models for the purposes of evaluating the potential benefits of using co-simulation between CONTAM and EnergyPlus. A set of Residential Prototype Building Models available from DOE has been modified by NIST and utilized to demonstrate the coupling process and the benefits of this coupling with respect to IAQ and energy analysis, and to evaluate multiple whole-building simulation methods related to infiltration, ventilation, and occupant exposure. These methods include an original EnergyPlus prototype model, the original model with NIST-based infiltration correlations, co-simulation between EnergyPlus and CONTAM, and stand-alone CONTAM simulations. Potential benefits will be explored related to the ability of co-simulation to address the effects of variations in building typology and ventilation system performance on contaminant transport results while leveraging the capabilities of whole-building energy analysis.

Probabilistic analysis of contaminant transport in fractured sedimentary rocks

Probabilistic analysis of contaminant transport in fractured sedimentary rocks

Design of landfill liners for fine grained soils using CTRAN/W

The management and disposal of municipal solid waste (MSW) in many countries has changed significantly. To overcome the risk to environment and humans, landfills are designed and constructed to dump the waste in the ground and covered with soil, vegetation to protect the environment. Engineered landfills are provided with various liner systems. Liners used in the landfill acts as a barrier to water, leachate and other liquid materials. Liners also protect the ground from solute concentration. In the present study, compacted clay liners of various thicknesses are used. A numerical model of a landfill with the clay liner is designed and analysis is performed using GeoStudio software. In this software CTRAN/W module is used for contaminant transport analysis. From the landfill at different radial distances three bore holes are provided with varying depths respectively, also clay liner thicknesses of 0.5 m, 1.0 m, 1.5 m. Tests on the soil like standard proctor test and hydraulic conductivity tests are conducted. Results shows, with the increase in liner thickness, time taken by the contaminant transport to reach bore wells increases. Results also show the rate of variation in concentration of the leachate at each bore well in certain time period.

Assessing the Energy and Indoor Air Quality Performance for a Three-Story Building Using an Integrated Model, Part One: The Need for Integration

In building applications, there is a dynamic interaction/coupling between the energy performance and the indoor air quality (IAQ) performance. Previously, the performance of energy consumption (EC) and IAQ has been evaluated independently. In this study, an energy performance model (EnergyPlus) and IAQ performance model (CONTAM: contaminant transport analysis) were simultaneously coupled as a new integrated simulation model in which the control variables were exchanged between the two models. Two scenarios were provided in this study for a three-story house. The first scenario addressed the effect of airtightness only. The second scenario, however, addressed the airtightness with an exhaust fan with an upgraded filter. In order to better analyze the accuracy of the simulations, the performance of the energy and IAQ were simulated independently using the EnergyPlus model and CONTAM model. Thereafter, the performance of the energy and IAQ were simulated using the present integrated simulation model. All simulations were conducted for the climatic conditions of Montreal and Miami. The results of the integrated simulation model showed that the exchange of control variables between both EnergyPlus and CONTAM produced accurate results for the performance of both energy and IAQ. Finally, the necessity of using the present integrated simulation model is discussed.

1 D contaminant transport through unsaturated stratified media using EFGM

In the present study, analysis of contaminant transport through one dimensional unsaturated stratified media using element free Galerkin method has been presented. Element free Galerkin method is a meshfree method. A FORTRAN code has been developed for the same. The developed model is compared with the results available in the literature and are found in good agreement. Further a parametric study has been conducted to examine the effects of various parameters like velocity, dispersivity, retardation factor and effect of saturation on the contaminant flow. The results presented conclude that transport of contaminant is retarded in unsaturated zone in comparison with the saturated zone.

Impact of Probability Distribution of Hydraulic Conductivity on Groundwater Contaminant Transport

In this study, a simple approach using effective hydraulic conductivity (Ke) was proposed to consider the spatial variability of K, and the impact of the probability density function (PDF) of K on contaminant transport in heterogeneous soil was investigated. To analyze the impact of the PDF of K according to the spatial variability of K, non-Gaussian random fields were generated for four probability distributions (Gaussian, log-Gaussian, Weibull, and gamma), and Ke was calculated from the random fields to represent the flow through heterogeneous media. Subsequently, contaminant transport analysis was easily performed by the closed-form solution, and probabilistic analysis was performed using a Monte Carlo simulation. The results show that the statistical properties of Ke were changed by the PDF and spatial variability of Kh, and the PDF of Kh has considerable effects on the probabilistic results for contaminant transport. In particular, the PDF has a greater impact on the probabilistic results when the autocorrelation distance is smaller (i.e., highly heterogeneous soil). Therefore, the selection of the PDF of K is very important for the stochastic modeling of contaminant transport, and the gamma distribution was found to be effective in expressing the probability distribution of K.

Spatial moment analysis of multispecies contaminant transport in porous media

Spatial moment analysis of multispecies contaminant transport in porous media

Design charts for contaminant transport throughslurry trench cutoff walls

Slurry trench cutoff walls with low-permeability backfill material, such as soil-bentonite and slag-cement-bentonite, are used widely for containment of subsurface pollution. In the design of slurry walls the potential service life for a given thickness or the wall thickness for a target service life are typically determined via analyses of one-dimensional contaminant transport. The difficulty of selecting appropriate inlet and outlet boundary conditions and the mathematical complexity of analytical solutions hinder engineers in undertaking a contaminant transport analysis–based design. Design charts for nondimensionalized effluent flux are presented by developing and using an analytical solution. The methodologies of using these charts in design are demonstrated.

Geochemical Evolution and Leachate Transport Beneath Two Carcass Burial Sites: A Field Investigation

Abstract. This study presents the first complete investigation using soil coring to evaluate the geochemical evolution of leachate plumes beneath existing livestock burial sites. The objective of the study was to broaden our understanding and provide evidence-based resources for minimizing the environmental impacts of mass-mortality carcass burial. Pre-existing livestock burial sites were selected for a detailed analysis of contaminant transport beneath and surrounding the sites in an attempt to determine the risk to soil and groundwater. This analysis entailed soil coring at the site along with specific ion and solution extraction analyses on the soil cores to provide detailed 2-D images of leachate movement around and below the burial sites. The first site, near Pierceland, Saskatchewan, was used in 2001 to bury euthanized elk potentially suffering from chronic wasting disease (CWD). The soil cores were taken seven years post-burial, and the extent of leachate transport, upon analysis of the soil cores, was 1 to 1.5 m of vertical transport of anions (Cl, alkalinity), as well as some cations arising from ion exchange reactions (Ca and Mg). Ammonium ions were attenuated near the bottom and in the first meter beneath the bottom of the trench. There was no indication of lateral movement of ions at this site. The second site, near McLean, Saskatchewan, was used in 1952 to bury carcasses of culled livestock during an emergency depopulation effort for disease control measures during Canada’s only outbreak of foot and mouth disease. This site was cored nearly 60 years post-burial and demonstrated that vertical leachate movement was relatively slow over the 60 years, with movement of up to 1 to 2 m. Due to the presence of sand lenses in and around the burial pit, horizontal movement of up to 10 m of anions, such as Cl and bicarbonate, was discovered. Ammonium ions were indicated within the confines of the burial pit and in the soil immediately surrounding the pit. Both sites demonstrated plume characteristics consistent with previous geochemical models, and both showed little impact to the immediate surrounding environment. This would appear to indicate that the burial site selection characteristics were appropriately determined and that many parts of Saskatchewan are suitable for mass quantities of livestock carcass burial in the event of catastrophic events such as disease outbreaks or natural disasters. Keywords: Carcass leachate, Contaminant transport, Groundwater, Livestock burial, Mortality, Site investigation, Soil.

A FRACTIONAL FUZZY SIMULATION METHOD FOR PREDICTING DISSOLVED TOLUENE AND OXYGEN CONCENTRATIONS IN AQUIFERS UNDER MICROBIAL ATTENUATION

This study proposes a modified fractional fuzzy simulation (MFFS) method to predict the toluene and oxygen concentrations in aquifers under microbial attenuation conditions. The method integrates the modeling of groundwater flow contaminant transport and fuzzy parameters analysis within a general framework. Compared to conventional fractional fuzzy simulation (FFS), decreased interior points of fuzzy parameters need to be used, thus reducing the simulation time. The method is applied to an aquifer of the Pinggu site in Beijing, China, where three parameters (i.e. longitudinal dispersivity, hydraulic conductivity and storage coefficient) are represented as fuzzy sets. Results from the case studies demonstrate that i) hydraulic conductivity has the most significant effect on toluene concentrations, while longitudinal dispersivity is rather significant, and storage coefficient has no apparent effect. ii) longitudinal dispersivity has the most significant effect on oxygen concentrations, while hydraulic conductivity is rather significant, and storage coefficient has no apparent effect. It is also observed that iii) the method is useful for not only site simulation, but also risk assessment, remediation design and process control under parameter uncertainty.

Constructing Markov matrices for real-time transient contaminant transport analysis for indoor environments

Predicting the movement of contaminants in the indoor environment has applications in tracking airborne infectious disease, ventilation of gaseous contaminants, and the isolation of spaces during biological attacks. Markov matrices provide a convenient way to perform contaminant transport analysis. However, no standardized method exists for calculating these matrices. A methodology based on set theory is developed for calculating contaminant transport in real-time utilizing Markov matrices from CFD flow data (or discrete flow field data). The methodology provides a rigorous yet simple strategy for determining the number and size of the Markov states, the time step associated with the Markov matrix, and calculation of individual entries of the Markov matrix. The procedure is benchmarked against scalar transport of validated airflow fields in enclosed and ventilated spaces. The approach can be applied to any general airflow field, and is shown to calculate contaminant transport over 3000 times faster than solving the corresponding scalar transport partial differential equation. This near real-time methodology allows for the development of more robust sensing and control procedures of critical care environments (clean rooms and hospital wards), small enclosed spaces (like airplane cabins) and high traffic public areas (train stations and airports).

Time series analysis of contaminant transport in the subsurface: Applications to conservative tracer and engineered nanomaterials

Accurately predicting the transport of contaminants in the field is subject to multiple sources of uncertainty due to the variability of geological settings, the complexity of field measurements, and the scarcity of data. Such uncertainties can be amplified when modeling some emerging contaminants, such as engineered nanomaterials, when a fundamental understanding of their fate and transport is lacking. Typical field work includes collecting concentration at a certain location for an extended period of time, or measuring the movement of plume for an extended period time, which would result in a time series of observation data. This work presents an effort to evaluate the possibility of applying time series analysis, particularly, autoregressive integrated moving average (ARIMA) models, to forecast contaminant transport and distribution in the subsurface environment. ARIMA modeling was first assessed in terms of its capability to forecast tracer transport at two field sites, which had different levels of heterogeneity. After that, this study evaluated the applicability of ARIMA modeling to predict the transport of engineered nanomaterials at field sites, including field measured data of nanoscale zero valent iron and (nZVI) and numerically generated data for the transport of nano-fullerene aggregates (nC60). This proof-of-concept effort demonstrates the possibility of applying ARIMA to predict the contaminant transport in the subsurface environment. Like many other statistical models, ARIMA modeling is only descriptive and not explanatory. The limitation and the challenge associated with applying ARIMA modeling to contaminant transport in the subsurface are also discussed.

Numerical analysis of advection-dominated contaminant transport in saturated porous media

In this paper, the time-dependent system of governing differential equation for contaminant transport in porous media is considered. Numerical solution of this equation indicates spurious spatial oscillations for different time steps and mesh sizes. The upwind finite element scheme (UFEM) is used to overcome the oscillations associated with the solution of two-dimensional transient contaminant transport equation under advection-dominated and purely advective conditions. The results of a conventional finite element model and the UFEM are compared with an analytical solution. In order to evaluate the robustness of UFEM, a cross comparison is made between this method and third-order total-variation-diminishing scheme which is broadly recognised as an oscillation-free method for solving advection-dominated problems. It is shown that the upwind finite element solution is free of oscillations and it minimises numerical dispersion. Furthermore, in upwind finite element method there is flexibility over the solution by using proper damping coefficients based on the nature of the problem.

Exact analytical solutions for contaminant transport in rivers 1. The equilibrium advection-dispersion equation

Abstract Analytical solutions of the advection-dispersion equation and related models are indispensable for predicting or analyzing contaminant transport processes in streams and rivers, as well as in other surface water bodies. Many useful analytical solutions originated in disciplines other than surface-water hydrology, are scattered across the literature, and not always well known. In this two-part series we provide a discussion of the advection-dispersion equation and related models for predicting concentration distributions as a function of time and distance, and compile in one place a large number of analytical solutions. In the current part 1 we present a series of one- and multi-dimensional solutions of the standard equilibrium advection-dispersion equation with and without terms accounting for zero-order production and first-order decay. The solutions may prove useful for simplified analyses of contaminant transport in surface water, and for mathematical verification of more comprehensive numerical transport models. Part 2 provides solutions for advective- dispersive transport with mass exchange into dead zones, diffusion in hyporheic zones, and consecutive decay chain reactions.