Special Issue "Subsurface Multiphase Flow and Contamination Remediation"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydrology".

Deadline for manuscript submissions: 20 May 2020.

Special Issue Editors

Dr. Kaveh Sookhak Lari
E-Mail Website
Guest Editor
Research Scientist at CSIRO, Perth, Australia
Interests: CFD; mass transport; multi-phase flows; subsurface NAPL behavior; environmental engineering
Dr. Robert J. Lenhard
E-Mail Website
Guest Editor
Former Senior Scientist at CSIRO and US National Laboratories
Interests: Multiphase flow; subsurface NAPL behavior; capillary pressure-relative permeability relations; soil physics; vadose zone

Special Issue Information

Dear Colleagues,

The accidental release of hazardous hydrophobic organic chemicals including light (L) and dense (D) non-aqueous phase liquids (NAPLs, such as petroleum hydrocarbons and chlorinated solvents respectively) into the subsurface is a significant environmental problem. Depending on their specific gravity, NAPLs form an immiscible liquid plume in the vadose zone and across the capillary fringe (for LNAPLs) or penetrate below the water table (DNAPLs). NAPLs may include hundreds of chemicals with significantly different solubility and volatilization attributes. Partitioning of NAPL compounds into gaseous and aqueous phase alter the physical and chemical characteristics of the gaseous and aqueous phases and the remaining NAPL. Ambient and natural phenomena such as capillary effects, hysteresis, and water table fluctuations can affect the mobility of the NAPL. Trapped or residual NAPL may form in the subsurface and serve as long-term sources of contamination. The interaction of biotic and abiotic processes in the subsurface can alter the mobility, mass, composition, and distribution of the chemicals in the NAPL. Eventually, remediation approaches to remove NAPLs reach their operational endpoints and may leave behind considerable amounts of subsurface contamination. The varied physical and chemical dynamics in the subsurface create complex multiphase, multicomponent, and multiscale issues when addressing subsurface NAPL contamination.

The aim of this Special Issue is to encourage the submission of works focused on various aspects of multiphase multicomponent flow, biotic and abiotic reactions, and multi-phase remediation of NAPLs.  We consider theoretical, computational and experimental papers addressing multiphase dynamics and measurement techniques at various scales (pore to Darcy and field scale). Papers addressing natural source zone depletion (NSZD) and the longevity of chemicals in different phases are also encouraged. Site characterization and case studies are considered only if they discuss novel observations and techniques. Papers on single-phase contamination transport and remediation (e.g., pump-and-treat) will not be given a priority.

Dr. Kaveh Sookhak Lari
Dr. Robert J. Lenhard
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • NAPL
  • multiphase
  • multicomponent
  • multiscale
  • transport phenomena
  • remediation
  • vadose zone
  • groundwater
  • NSZD
  • endpoint
  • longevity
  • modeling
  • experiment
  • measurement

Published Papers (4 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Open AccessArticle
Testing an Analytical Model for Predicting Subsurface LNAPL Distributions from Current and Historic Fluid Levels in Monitoring Wells: A Preliminary Test Considering Hysteresis
Water 2019, 11(11), 2404; https://doi.org/10.3390/w11112404 - 15 Nov 2019
Abstract
Knowledge of subsurface light nonaqueous phase liquid (LNAPL) saturation is important for developing a conceptual model and a plan for addressing LNAPL contaminated sites. Investigators commonly predict LNAPL mobility and potential recoverability using information such as LNAPL physical properties, subsurface characteristics, and LNAPL [...] Read more.
Knowledge of subsurface light nonaqueous phase liquid (LNAPL) saturation is important for developing a conceptual model and a plan for addressing LNAPL contaminated sites. Investigators commonly predict LNAPL mobility and potential recoverability using information such as LNAPL physical properties, subsurface characteristics, and LNAPL saturations. Several models exist that estimate the LNAPL specific volume and transmissivity from fluid levels in monitoring wells. Commonly, investigators use main drainage capillary pressure–saturation relations because they are more frequently measured and available in the literature. However, main drainage capillary pressure–saturation relations may not reflect field conditions due to capillary pressure–saturation hysteresis. In this paper, we conduct a preliminary test of a recent analytical model that predicts subsurface LNAPL saturations, specific volume, and transmissivity against data measured at a LNAPL contaminated site. We call our test preliminary because we compare only measured and predicted vertical LNAPL saturations at a single site. Our results show there is better agreement between measured and predicted LNAPL saturations when imbibition capillary pressure–saturation relations are employed versus main drainage capillary pressure–saturation relations. Although further testing of the model for different conditions and sites is warranted, the preliminary test of the model was positive when consideration was given to capillary pressure–saturation hysteresis, which suggests the model can yield reasonable predictions that can help develop and update conceptual site models for addressing subsurface LNAPL contamination. Parameters describing capillary pressure–saturation relations need to reflect conditions existing at the time when the fluid levels in a well are measured. Full article
(This article belongs to the Special Issue Subsurface Multiphase Flow and Contamination Remediation)
Show Figures

Figure 1

Open AccessArticle
Quantification of Uncertainties from Image Processing and Analysis in Laboratory-Scale DNAPL Release Studies Evaluated by Reflective Optical Imaging
Water 2019, 11(11), 2274; https://doi.org/10.3390/w11112274 - 30 Oct 2019
Abstract
Subsurface DNAPL (dense non-aqueous phase liquid) contamination from (un-) intentional spilling typically leads to severe environmental hazards. A large number of studies have demonstrated the relevance of DNAPL source zone geometry for the determination of contaminant plume propagation in groundwater. Optical imaging represents [...] Read more.
Subsurface DNAPL (dense non-aqueous phase liquid) contamination from (un-) intentional spilling typically leads to severe environmental hazards. A large number of studies have demonstrated the relevance of DNAPL source zone geometry for the determination of contaminant plume propagation in groundwater. Optical imaging represents a promising non-invasive method for identifying DNAPL saturation without disturbing multiphase flow dynamics. However, workflow and image analysis methodologies have not been sufficiently developed or described for general application to related experimental efforts. For example, the choice of dye(s) used for phase colorization affects image processing and can bias final estimations of DNAPL saturations. In this study, we perform a series of DNAPL migration and entrapment studies in transparent tanks that are filled with three different types of porous media. Different dyes are used and raw images are acquired. Subsequently, these are used to evaluate a suite of image processing and analysis approaches, which are organized into a workflow. Our approach allows for us to identify key image processing and analysis steps that introduce the most error. Applicable dye configurations led to uncertainties of up to 41% depending on the selection of processing steps. Based on these findings, it was possible to delineate a flexible framework for image processing and analysis that has the potential for transfer and application in other tank experiment setups. Full article
(This article belongs to the Special Issue Subsurface Multiphase Flow and Contamination Remediation)
Show Figures

Figure 1

Open AccessArticle
Toward a New Generation of Two-Fluid Flow Models Based on the Thermodynamically-Constrained Averaging Theory
Water 2019, 11(11), 2260; https://doi.org/10.3390/w11112260 - 28 Oct 2019
Abstract
Traditional models of two-fluid flow through porous media at the macroscale have existed for nearly a century. These phenomenological models are not firmly connected to the microscale; thermodynamic constraints are not enforced; empirical closure relations are well known to be hysteretic; fluid pressures [...] Read more.
Traditional models of two-fluid flow through porous media at the macroscale have existed for nearly a century. These phenomenological models are not firmly connected to the microscale; thermodynamic constraints are not enforced; empirical closure relations are well known to be hysteretic; fluid pressures are typically assumed to be in a local equilibrium state with fluid saturations; and important quantities such as interfacial and curvilinear geometric extents, tensions, and curvatures, known to be important from microscale studies, do not explicitly appear in traditional macroscale models. Despite these shortcomings, the traditional model for two-fluid flow in porous media has been extensively studied to develop efficient numerical approximation methods, experimental and surrogate measure parameterization approaches, and convenient pre- and post-processing environments; and they have been applied in a large number of applications from a variety of fields. The thermodynamically constrained averaging theory (TCAT) was developed to overcome the limitations associated with traditional approaches, and we consider here issues associated with the closure of this new generation of models. It has been shown that a hysteretic-free state equation exists based upon integral geometry that relates changes in volume fractions, capillary pressure, interfacial areas, and the Euler characteristic. We show an analysis of how this state equation can be parameterized with a relatively small amount of data. We also formulate a state equation for resistance coefficients that we show to be hysteretic free, unlike traditional relative permeability models. Lastly, we comment on the open issues remaining for this new generation of models. Full article
(This article belongs to the Special Issue Subsurface Multiphase Flow and Contamination Remediation)
Show Figures

Figure 1

Open AccessArticle
Numerical Modeling of Multiphase Extraction (MPE) Aiming at LNAPL Recovery in Tropical Soils
Water 2019, 11(11), 2248; https://doi.org/10.3390/w11112248 - 26 Oct 2019
Abstract
Subsurface contamination by light non-aqueous phase liquids (LNAPL) is a widespread global problem that requires appropriate techniques to remediate soil and groundwater. In this paper, the subsurface transport over multiple phases (STOMP) model was used to simulate LNAPL multiphase flow and transport during [...] Read more.
Subsurface contamination by light non-aqueous phase liquids (LNAPL) is a widespread global problem that requires appropriate techniques to remediate soil and groundwater. In this paper, the subsurface transport over multiple phases (STOMP) model was used to simulate LNAPL multiphase flow and transport during multiphase extraction (MPE) application in two Brazilian tropical soils (silty sand and oxisol) contaminated by diesel. The model was applied to a hypothetical contamination site, with the initial LNAPL thickness observed in well extraction. The first part consisted of the MPE system sensitivity analysis, varying the applied vacuum and tip tube position. The Van Genuchten α parameter and hydraulic conductivity were the properties that most affected LNAPL saturation and fluid extraction volumes. Suitable applied vacuum and tip tube position parametrization was imperative for the efficiency of LNAPL extraction. After the definition of an appropriate MPE system configuration, simulations demonstrated that the immobile LNAPL saturation affected fluid extraction and diesel oil concentrations in aqueous and gas saturation. The model applied is able to predict LNAPL contaminant behavior in porous media during MPE technique application. Full article
(This article belongs to the Special Issue Subsurface Multiphase Flow and Contamination Remediation)
Show Figures

Figure 1

Back to TopTop