Special Issue "Remediation of NAPL-Contaminated Groundwater Aquifers"

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

Deadline for manuscript submissions: 30 September 2022 | Viewed by 1820

Special Issue Editors

Prof. Dr. Wei-Cheng Lo
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Guest Editor
Department of Hydraulic and Ocean Engineering, National Cheng Kung University, No.1, University Road, Tainan 701, Taiwan
Interests: soil-water physics; modeling multiphase flow and transport in deformable porous media; saltwater intrusion into coastal aquifers; remediation of groundwater aquifers and enhanced oil recovery; poro-mechanics in fluid-containing porous media; mechanical interaction connecting geophysics to subsurface hydrology; soil erosion and conservation; flood hydrology
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Prof. Dr. Chuen-Fa Ni
E-Mail Website
Guest Editor
Graduate Institute of Applied Geology, National Central University, No. 300, Zhongda Rd., Zhongli District, Taoyuan City 320317, Taiwan
Interests: groundwater modeling; hydrogeology; stochastic groundwater hydrology; data assimilation
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Dr. Heejun Suk
E-Mail Website
Guest Editor
Center for HLW Geological Disposal Geology Division Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Korea
Interests: innovative numerical algorithms for flow and transport; analytical solution of multispecies transport; multiphase flow and transport; hydrogeology in coastal aquifer including seawater intrusion and inland contamination; mathematical analysis of chemical and physical data; artificial recharge
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Petroleum hydrocarbons and organic solvents are common contaminants in subsurface environments, posing a serious threat to groundwater resources.  These liquids, immiscible with water and moving as discrete liquid phases, are often referred to as nonaqueous-phase liquids (NAPLs).  When spilled accidentally on the ground or leaking from storage facilities in sufficient volumes, NAPLs migrate downward through the vadose zone due to gravitational and capillary forces, eventually reaching the water table.  During the migration process, a portion of NAPLs may be trapped within the pore space in the form of blobs or remain as films around soil particles held by capillary forces.  These residual NAPL distributions are complex and can act as long-term sources of contamination. Because entrapped NAPLs are so difficult to dislodge, extraction of NAPL contaminants from groundwater aquifers has been an area of active research in environmental protection and remediation.  A wide variety of physicochemical and biological remediation technologies has been developed to remove NAPLs from contaminated subsurface zones.   This special issue is dedicated to bringing current knowledge on innovative technologies and methodologies to provide a comprehensive, in-depth analysis of groundwater remediation and quantify its social impacts.  The potential topics of the special issue include, but are not limited to:

  1. Flow of immiscible fluids in soils
  2. Sampling, modeling, and characterization of contaminated sites
  3. Source zone identification
  4. Remediation strategies and cost-effective designs
  5. Numerical simulation for characterizing contaminant transport
  6. Analytical solution for analysis on solute transport behavior
  7. Monitoring techniques and site management
  8. Other topics on applications of remediation of NAPL-contaminated aquifers

We welcome both original research papers and review papers that provide the community with the most recent advancements in all aspects of NAPL-contaminated site characterization and remediation.

Prof. Dr. Wei-Cheng Lo
Prof. Dr. Chuen-Fa Ni
Dr. Heejun Suk
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 submissions that pass pre-check are 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 semimonthly 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 2200 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

  • NAPLs
  • contamination
  • remediation
  • groundwater
  • entrapped
  • analytical solution
  • numerical simulation
  • vadose zone
  • multiphase flow and transport

Published Papers (2 papers)

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Research

Article
Application of a Developed Numerical Model for Surfactant Flushing Combined with Intermittent Air Injection at Field Scale
Water 2022, 14(3), 316; https://doi.org/10.3390/w14030316 - 21 Jan 2022
Viewed by 692
Abstract
Surfactant flushing with intermittent air injection, referred to as enhanced flushing, has been proposed at a site in Korea contaminated by military activity to overcome the difficulty of treatment caused by a layered geological structure. In this study, we developed a simple numerical [...] Read more.
Surfactant flushing with intermittent air injection, referred to as enhanced flushing, has been proposed at a site in Korea contaminated by military activity to overcome the difficulty of treatment caused by a layered geological structure. In this study, we developed a simple numerical model for exploring the effects of various physical and chemical processes associated with enhanced flushing on pollutant removal efficiency and applied it in a field-scale test. This simple numerical model considers only enhanced hydraulic conductivity rather than all of the interacting parameters associated with the complex chemical and physical processes related to air and surfactant behavior during enhanced flushing treatment. In the numerical experiment, the removal efficiency of residual non-aqueous phase liquid (NAPL) was approximately 12% greater with enhanced, rather than conventional, flushing because the hydraulic conductivity of the low-permeability layer was enhanced 5-fold, thus accelerating surfactant transport in the low-permeability layer and facilitating enhanced dissolution of residual NAPL. To test whether the enhanced flushing method is superior to conventional flushing, as observed in the field-scale test, successive soil flushing operations were simulated using the newly developed model, and the results were compared to field data. Overall, the simulation results aligned well with the field data. Full article
(This article belongs to the Special Issue Remediation of NAPL-Contaminated Groundwater Aquifers)
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Article
Importance of Infiltration Rates for Fate and Transport of Benzene in High-Tiered Risk-Based Assessment Considering Korean Site-Specific Factors at Contaminated Sites
Water 2021, 13(24), 3646; https://doi.org/10.3390/w13243646 - 18 Dec 2021
Viewed by 644
Abstract
Widely used conservative approaches for risk-based assessments of the subsurface transport processes have been calculated using simple analytical equations or general default values. Higher-tier risk assessment of contaminated sites requires the numerical models or additional site-specific values for input parameters. Previous studies have [...] Read more.
Widely used conservative approaches for risk-based assessments of the subsurface transport processes have been calculated using simple analytical equations or general default values. Higher-tier risk assessment of contaminated sites requires the numerical models or additional site-specific values for input parameters. Previous studies have focused on the development of sophisticated models fit into risk-based frameworks. Our study mainly aims to explore the applicability of site-specific parameters and to modify the risk-based fate and transport model according to the types of the site-specific parameters. To apply the modified fate and transport equation and the site-specific default infiltration range, this study assessed the source depletion, leachate concentrations, and exposure concentration of benzene, which is a representative organic contaminant. The numerical models consist of two continuous processes, the fate and transport of contaminants from (1) the soil to the groundwater table in the vadose zone and subsequently (2) from the groundwater table to exposure wells in the saturated zone. Spatially varied Korean domestic recharge data were successfully incorporated into site-specific infiltration parameters in the models. The numerical simulation results were expressed as transient time series of concentrations over time. Results presented the narrow range of predicted concentrations at the groundwater table when site-specific infiltration was applied, and the dilution–attenuation factors for the unsaturated zone (DAFunsat) were derived based on the prediction. When a contaminant travels to the longest path length of 10 m with a source depth of 1 m in the vadoze zone, the simulated DAFunsat ranged from 3 to 4. The highest DAFunsat simulation results are close to 1 when contaminants travel to a source depth of 5 m and the shortest path length of 1 m. In the saturated aquifer below the contaminated sites, the variation in exposure concentration with time at monitoring wells is detected differently depending on the depth of the saturated zone. Full article
(This article belongs to the Special Issue Remediation of NAPL-Contaminated Groundwater Aquifers)
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