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Dhulia A, Abou-Khalil C, Kewalramani J, Sarkar D, Boufadel MC. Mobilization of per- and poly-fluoroalkyl substances (PFAS) in soils with different organic matter contents. CHEMOSPHERE 2024; 361:142503. [PMID: 38825242 DOI: 10.1016/j.chemosphere.2024.142503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/29/2024] [Accepted: 05/30/2024] [Indexed: 06/04/2024]
Abstract
There is considerable interest in addressing soils contaminated with per- and polyfluoroalkyl substances (PFAS) because of the PFAS in the environment and associated health risks. The neutralization of PFAS in situ is challenging. Consequently, mobilizing the PFAS from the contaminated soils into an aqueous solution for subsequent handling has been pursued. Nonetheless, the efficiency of mobilization methods for removing PFAS can vary depending on site-specific factors, including the types and concentrations of PFAS compounds, soil characteristics. In the present study, the removal of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) from artificially contaminated soils was investigated in a 2D laboratory setup using electrokinetic (EK) remediation and hydraulic flushing by applying a hydraulic gradient (HG) for a duration of 15 days. The percent removal of PFOA by EK was consistent (∼80%) after a 15-day treatment for all soils. The removal efficiency of PFOS by EK significantly varied with the OM content, where the PFOS removal increased from 14% at 5% OM to 60% at 50% OM. With HG, the percent removal increased for both PFOA and PFOS from about 20% at 5% OM up to 80% at 75% OM. Based on the results, the mobilization of PFAS from organic soil would be appropriate using both hydraulic flushing and EK considering their applicability and advantages over each other for site-specific factors and requirements.
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Affiliation(s)
- Anirban Dhulia
- Center for Natural Resources, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Charbel Abou-Khalil
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, South Bend, IN, 46556, USA
| | | | - Dibyendu Sarkar
- Department of Civil, Environmental and Ocean Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Michel C Boufadel
- Center for Natural Resources, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA.
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2
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Braun AB, Visentin C, Thomé A. Design of a central tool for sustainability evaluation and weighting to decision-making support of contaminated soils remediation. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119624. [PMID: 38043305 DOI: 10.1016/j.jenvman.2023.119624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/03/2023] [Accepted: 11/15/2023] [Indexed: 12/05/2023]
Abstract
Sustainable remediation remains unstandardized and ambiguously regulated, thereby limiting its adoption in the management of contaminated areas. Although a considerable number of tools are available for this purpose, numerous shortcomings continue to be detected, especially with regard to the integration of a complete assessment of impact and sustainability into a single framework. In view of these problems, the objective in this study was to develop and validate an integrated tool for assessing the sustainability of remediation techniques for contaminated soils. To support the sustainability analysis, were prepared impact assessment matrices, which list components and criteria for obtaining integrated impact scores for each sustainability dimension/pillar (i.e., social, economic, and environmental), factor, and component. These impact scores were incorporated and fitted into a mathematical model used to ascertain the sustainability of the techniques. The tool was subsequently validated by comparing and analyzing the sustainability with which five techniques: phytoremediation, electrokinetics and excavation/disposal (Case Study I), nanoremediation and soil washing (Case Study II). The techniques' probabilities of sustainability followed the order presented in the preceding statement. The determination of sustainability was supported by the direct interaction between the effects derived under each dimension and technique. These findings led to the conclusion that the proposed tool prioritizes the basic principles of sustainability, which call for harmony among the three pillars, and that it is a favorable instrument for the evaluation and selection of a sustainable remediation technique.
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Affiliation(s)
- Adeli Beatriz Braun
- Graduate Program in Civil and Environmental Engineering, University of Passo Fundo, BR 285, São José, 99052-900, Passo Fundo, Rio Grande do Sul, Brazil.
| | - Caroline Visentin
- Graduate Program in Civil and Environmental Engineering, University of Passo Fundo, BR 285, São José, 99052-900, Passo Fundo, Rio Grande do Sul, Brazil
| | - Antônio Thomé
- Graduate Program in Civil and Environmental Engineering, University of Passo Fundo, BR 285, São José, 99052-900, Passo Fundo, Rio Grande do Sul, Brazil
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3
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Akansha J, Thakur S, Chaithanya MS, Gupta BS, Das S, Das B, Rajasekar N, Priya K. Technological and economic analysis of electrokinetic remediation of contaminated soil: A global perspective and its application in Indian scenario. Heliyon 2024; 10:e24293. [PMID: 38304840 PMCID: PMC10831613 DOI: 10.1016/j.heliyon.2024.e24293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 01/05/2024] [Accepted: 01/05/2024] [Indexed: 02/03/2024] Open
Abstract
Globally million hectares of land annually is getting contaminated by heavy metalloids like As, Cd, Cr, Hg, Pb, Co, Cu, Ni, Zn, and Se, with current concentrations in soil above geo-baseline or regulatory standards. The heavy metals are highly toxic, mobile, and persistent and hence require immediate and effective mitigation. There are many available remediation techniques like surface capping, encapsulation, landfilling, soil flushing, soil washing, electrokinetic extraction, stabilization, solidification, vitrification, phytoremediation, and bioremediation which have been evolved to clean up heavy metal-contaminated sites. Nevertheless, all of the technologies have some applicability and limitations making the soil remediation initiative unsustainable. Among the available technologies, electrokinetic remediation (EKR) has been comparatively recognized to mitigate contaminated sites via both in-situ and ex-situ approaches due to its efficiency, suitability for use in low permeability soil, and requirement of low potential gradient. The work critically analyzes the EKR concerning techno, economic, and sustainability aspect for evaluating its application on various substrates and environmental conditions. The current soil contamination status in India is presented and the application of EKR for the heavy metal remediation from soil has been evaluated. The present work summaries a comprehensive and exhaustive review on EKR technology proving its effectiveness for a country like India where the huge amount of waste generated could not be treated due to lack of infrastructure, technology, and economic constraints.
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Affiliation(s)
- J. Akansha
- Department of Environment and Water Resources Engineering, School of Civil Engineering (SCE), Vellore Institute of Technology, Katpadi, Vellore, Tamil Nadu, 632014, India
| | - Somil Thakur
- Department of Environment and Water Resources Engineering, School of Civil Engineering (SCE), Vellore Institute of Technology, Katpadi, Vellore, Tamil Nadu, 632014, India
| | - M Sai Chaithanya
- Department of Environment and Water Resources Engineering, School of Civil Engineering (SCE), Vellore Institute of Technology, Katpadi, Vellore, Tamil Nadu, 632014, India
| | - Bhaskar Sen Gupta
- School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh Campus, Edinburgh, EH14 4AS, Scotland, UK
| | - Sovik Das
- Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Bhaskar Das
- Department of Environment and Water Resources Engineering, School of Civil Engineering (SCE), Vellore Institute of Technology, Katpadi, Vellore, Tamil Nadu, 632014, India
| | - N. Rajasekar
- Department of Energy and Power Electronics, School of Electrical Engineering, Vellore Institute of Technology, Katpadi, Vellore, Tamil Nadu, 632014, India
| | - K. Priya
- Department of Energy and Power Electronics, School of Electrical Engineering, Vellore Institute of Technology, Katpadi, Vellore, Tamil Nadu, 632014, India
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Uwayezu JN, Ren Z, Sonnenschein S, Leiviskä T, Lejon T, van Hees P, Karlsson P, Kumpiene J, Carabante I. Combination of separation and degradation methods after PFAS soil washing. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:168137. [PMID: 37890625 DOI: 10.1016/j.scitotenv.2023.168137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/05/2023] [Accepted: 10/24/2023] [Indexed: 10/29/2023]
Abstract
The current study evaluated a three-stage treatment to remediate PFAS-contaminated soil. The treatment consisted of soil washing, foam fractionation (FF), and electrochemical oxidation (EO). The possibility of replacing the third stage, i.e., EO, with an adsorption process was also assessed. The contamination in the studied soils was dominated by perfluorooctane sulfonate (PFOS), with a concentration of 760 and 19 μg kg-1 in soil I and in soil II, accounting for 97 % and 70 % of all detected per-and polyfluoroalkyl substances (PFAS). Before applying a pilot treatment of soil, soil washing was performed on a laboratory scale, to evaluate the effect of soil particle size, initial pH and a liquid-to-soil ratio (L/S) on the leachability of PFAS. A pilot washing system generated soil leachate that was subsequently treated using FF and EO (or adsorption) and then reused for soil washing. The results indicated that the leaching of PFAS occurred easier in 0.063-1 mm particles than in the soil particles having a size below 0.063 mm. Both alkaline conditions and a continual replacement of the leaching solution increased the leachability of PFAS. The analysis using one-way ANOVA showed no statistical difference in means of PFOS washed out in laboratory and pilot scales. This allowed estimating twenty washing cycles using 120 L water to reach 95 % PFOS removal in 60 kg soil. The aeration process removed 95-99 % PFOS in every washing cycle. The EO and adsorption processes achieved similar results removing up to 97 % PFOS in concentrated soil leachate. The current study demonstrated a multi-stage treatment as an effective and cost-efficient method to permanently clean up PFAS-contaminated soil.
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Affiliation(s)
- Jean Noel Uwayezu
- Waste Science and Technology, Luleå University of Technology, Luleå, Sweden.
| | - Zhongfei Ren
- Chemical Process Engineering, University of Oulu, Oulu, Finland
| | - Sarah Sonnenschein
- Waste Science and Technology, Luleå University of Technology, Luleå, Sweden
| | - Tiina Leiviskä
- Chemical Process Engineering, University of Oulu, Oulu, Finland
| | - Tore Lejon
- Department of Chemistry, UiT-The Arctic University of Norway, Norway
| | | | | | - Jurate Kumpiene
- Waste Science and Technology, Luleå University of Technology, Luleå, Sweden
| | - Ivan Carabante
- Waste Science and Technology, Luleå University of Technology, Luleå, Sweden
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Rahman S, Saito M, Yoshioka S, Ni S, Wong KH, Mashio AS, Begum ZA, Rahman IMM, Ohta A, Hasegawa H. Evaluation of newly designed flushing techniques for on-site remediation of arsenic-contaminated excavated debris. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:112052-112070. [PMID: 37824052 DOI: 10.1007/s11356-023-30140-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023]
Abstract
Excavated debris (soil and rock) contaminated with geogenic arsenic (As) is an increasing concern for regulatory organizations and construction stakeholders. Chelator-assisted soil flushing is a promising method for practical on-site remediation of As-contaminated soil, offering technical, economic, and environmental benefits. Ethylenediaminetetraacetic acid (EDTA) is the most prevalent chelator used for remediating As-contaminated soil. However, the extensive environmental persistence and potential toxicity of EDTA necessitate the exploration of eco-compliant alternatives. In this study, the feasibility of the conventional flushing method pump-and-treat and two newly designed immersion and sprinkling techniques were evaluated at the laboratory scale (small-scale laboratory experiments) for the on-site treatment of As-contaminated excavated debris. Two biodegradable chelators, L-glutamic acid-N,N'-diacetic acid (GLDA) and 3-hydroxy-2,2'-iminodisuccinic acid (HIDS), were examined as eco-friendly substitutes for EDTA. Additionally, this study highlights a useful post-treatment measure to ensure minimal mobility of residual As in the chelator-treated debris residues. The pump-and-treat method displayed rapid As-remediation (t, 3 h), but it required a substantial volume of washing solution (100 mL g-1). Conversely, the immersion technique demonstrated an excellent As-extraction rate using a relatively smaller washing solution (0.33 mL g-1) and shorter immersion time (t, 3 h). In contrast, the sprinkling technique showed an increased As-extraction rate over an extended period (t, 48 h). Among the chelators employed, the biodegradable chelator HIDS (10 mmol L-1; pH, 3) exhibited the highest As-extraction efficiency. Furthermore, the post-treatment of chelator-treated debris with FeCl3 and CaO successfully reduced the leachable As content below the permissible limit.
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Affiliation(s)
- Shafiqur Rahman
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan.
| | - Makoto Saito
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Shoji Yoshioka
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Shengbin Ni
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Kuo H Wong
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Asami S Mashio
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Zinnat A Begum
- Department of Civil Engineering, Southern University, Arefin Nagar, Bayezid Bostami, Chattogram, 4210, Bangladesh
| | - Ismail M M Rahman
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, Fukushima City, 960-1296, Japan
| | - Akio Ohta
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Hiroshi Hasegawa
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
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6
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Abou-Khalil C, Kewalramani J, Zhang Z, Sarkar D, Abrams S, Boufadel MC. Effect of clay content on the mobilization efficiency of per- and polyfluoroalkyl substances (PFAS) from soils by electrokinetics and hydraulic flushing. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 322:121160. [PMID: 36716947 DOI: 10.1016/j.envpol.2023.121160] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/15/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
The need for the efficient remediation of soils impacted by per- and polyfluoroalkyl substances (PFAS) is substantially growing because of the notable upsurge in societal and regulatory awareness of this class of chemicals. To remediate PFAS-contaminated soils using mobilization approaches, the choice of appropriate techniques highly depends on the soil's composition, particularly the clay content, which significantly affects the soil's permeability. Here, we investigated the PFAS mobilization efficiency from soils with different clay contents by using two techniques: electrokinetic (EK) remediation and hydraulic flushing. Artificial kaolinite was added to a loamy sand soil to prepare four soil blends with clay contents of 5, 25, 50, and 75%, each contaminated with perfluorooctanoic acid (PFOA) and perfulorooctanesulfonic acid (PFOA) at 10,000 μg/kg. EK remediation was conducted by applying a low voltage (30 V) with a current of 100 mA, and hydraulic flushing was carried out by applying a hydraulic gradient (HG) with a slope of 6.7%. Results show that, with a 14-day treatment duration, the EK-mobilization efficiency was enhanced substantially with the increase of clay content (removal of PFOS increased from 20% at 5% clay to 80% at 75% clay), most likely due to the increase of electroosmotic flow due to the higher content of particles having a zeta potential (i.e., clay). For HG, increasing the clay content significantly suppressed the mobilization of PFAS (removal of PFOS decreased from 40% at 5% clay to 10% at 75% clay) due to a notable decrease in the soil's permeability. Based on the results, applying hydraulic flushing and washing techniques for mobilizing PFAS would be appropriate when treating permeable soils with a maximum clay content of about 25%; otherwise, other suitable mobilization techniques such as EKs should be considered.
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Affiliation(s)
- Charbel Abou-Khalil
- Center for Natural Resources, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Jitendra Kewalramani
- Center for Natural Resources, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Zhiming Zhang
- Department of Civil, Environmental and Ocean Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Dibyendu Sarkar
- Department of Civil, Environmental and Ocean Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Stewart Abrams
- Langan Engineering and Environmental Services, Inc., 300 Kimball Dr., Parsippany, NJ 07054, USA
| | - Michel C Boufadel
- Center for Natural Resources, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA.
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7
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Schaefer CE, Lavorgna GM, Lippincott DR, Nguyen D, Schaum A, Higgins CP, Field J. Leaching of Perfluoroalkyl Acids during Unsaturated Zone Flushing at a Field Site Impacted with Aqueous Film Forming Foam. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:1940-1948. [PMID: 36689630 DOI: 10.1021/acs.est.2c06903] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
While several studies have focused on perfluoroalkyl acid (PFAA) leaching from soils, field studies evaluating the relationship between PFAA mass removal and porewater concentrations as the PFAA source becomes depleted are lacking. Herein, in situ water flushing was performed at a site historically impacted with AFFF to accelerate the leaching of PFAAs from unsaturated soils in a highly characterized field test cell. Porous cup suction lysimeters were used to assess the changes in PFAA porewater concentrations as a function of PFAA mass removal from the unsaturated soils, where flushing was intermittently paused to determine ambient PFAA porewater concentrations. Results showed that the fractional decreases in PFAA porewater concentrations during flushing exceeded the fractional decrease in PFAA mass removal from the soil. PFOS porewater concentrations decrease by 76% (with negligible rebound) compared to only a 7.4% decrease in overall PFOS mass removed from the unsaturated zone. Overall, the results observed herein suggest that, when considering soil impacts to groundwater, less stringent soil cleanup criteria than those that consider an equivalent relationship between mass removal and mass discharge may be appropriate. In addition, remedial approaches that remove only a modest fraction of the PFAA soil mass may be protective of underlying groundwater, particularly for perfluorinated sulfonates with at least six carbons.
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Affiliation(s)
- Charles E Schaefer
- CDM Smith, 110 Fieldcrest Avenue, #8, 6th Floor, Edison, New Jersey08837, United States
| | - Graig M Lavorgna
- APTIM Federal Services, 17 Princess Rd, Lawrenceville, New Jersey08648, United States
| | - David R Lippincott
- APTIM Federal Services, 17 Princess Rd, Lawrenceville, New Jersey08648, United States
| | - Dung Nguyen
- CDM Smith, 14432 SE Eastgate Way, # 100, Bellevue, Washington98007, United States
| | - Andre Schaum
- Department of Molecular and Environmental Toxicology, Oregon State University, 1007 Agricultural and Life Science Building, Corvallis, Oregon97331, United States
| | - Christopher P Higgins
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado80401, United States
| | - Jennifer Field
- Department of Molecular and Environmental Toxicology, Oregon State University, 1007 Agricultural and Life Science Building, Corvallis, Oregon97331, United States
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8
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Pyrolysis of Trifluoroacetic Acid and Trifluoroacetic Anhydride Studied with Mass Spectrometry and Synchrotron Radiation: Decomposition and Free Radical Formation. ChemistrySelect 2023. [DOI: 10.1002/slct.202202897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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9
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Neshati J, Biabanaki F, Shariatmadari N. An investigation into the efficiency of electrokinetic and electrokinetic coupled with calcium peroxide permeable reactive barriers techniques for soil remediation using a statistical analysis. ENVIRONMENTAL MONITORING AND ASSESSMENT 2022; 195:145. [PMID: 36418576 DOI: 10.1007/s10661-022-10736-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
The current study emphasizes on the applicability of combining the electrokinetic (EK) and permeable reactive barriers (PRB) techniques compared to the simple EK technique. For this purpose, a statistical analysis is conducted using the Fractional Factorial Design statistical method. Also, General Linear Model and Two-sample T-Test analyzes are considered to clarify which type of soil remediation technique represents the highest efficiency. Calcium peroxide, an affordable material with easy capability for cultivation, is utilized in the PRB process to eliminate the soil from diesel contamination. The experiments were performed for 3 days and 10 days, according to which the initial contamination rates of 10 and 20% were selected, and the applied voltages were 20 V and 30 V. Using the innovative remediation technique, the experiments were conducted for 10 days with 20% initial pollution content and the applied voltage of 30 V, the initial gasoil content was about 190.5 mg/g, and after applying the proposed technique, the average final pollution content throughout soil reached approximately 37 mg/g. This experiment was also conducted for the approximately initial gasoil content of 185, 206, and 191 mg/g, which led to the removal efficiency of 79.59%, 78.93%, and 79.15%, respectively. The main novelty of this paper is attributed to the use of calcium peroxide in the EK-PRB technique and the statistical analysis conducted in this study that indicates the remarkable efficiency of the proposed approach. It was also revealed that the efficiency of the proposed technique is on par with the other state-of-art ones presented in the literature and even sometimes outperforms them.
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Affiliation(s)
- Jaber Neshati
- Research Institute of Petroleum Industry (RIPI), PO Box, 14665-137, Tehran, Iran.
| | - Faraz Biabanaki
- Dept. of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, 16846-13114, Iran
| | - Nader Shariatmadari
- Dept. of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, 16846-13114, Iran
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Kumar M, Bolan N, Jasemizad T, Padhye LP, Sridharan S, Singh L, Bolan S, O'Connor J, Zhao H, Shaheen SM, Song H, Siddique KHM, Wang H, Kirkham MB, Rinklebe J. Mobilization of contaminants: Potential for soil remediation and unintended consequences. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 839:156373. [PMID: 35649457 DOI: 10.1016/j.scitotenv.2022.156373] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
Land treatment has become an essential waste management practice. Therefore, soil becomes a major source of contaminants including organic chemicals and potentially toxic elements (PTEs) which enter the food chain, primarily through leaching to potable water sources, plant uptake, and animal transfer. A range of soil amendments are used to manage the mobility of contaminants and subsequently their bioavailability. Various soil amendments, like desorbing agents, surfactants, and chelating agents, have been applied to increase contaminant mobility and bioavailability. These mobilizing agents are applied to increase the contaminant removal though phytoremediation, bioremediation, and soil washing. However, possible leaching of the mobilized pollutants during soil washing is a major limitation, particularly when there is no active plant uptake. This leads to groundwater contamination and toxicity to plants and soil biota. In this context, the present review provides an overview on various soil amendments used to enhance the bioavailability and mobility of organic and inorganic contaminants, thereby facilitating increased risk when soil is remediated in polluted areas. The unintended consequences of the mobilization methods, when used to remediate polluted sites, are discussed in relation to the leaching of mobilized contaminants when active plant growth is absent. The toxicity of targeted and non-targeted contaminants to microbial communities and higher plants is also discussed. Finally, this review work summarizes the existing research gaps in various contaminant mobilization approaches, and prospects for future research.
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Affiliation(s)
- Manish Kumar
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India
| | - Nanthi Bolan
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA 6001, Australia; The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia.
| | - Tahereh Jasemizad
- Department of Civil and Environmental Engineering, Faculty of Engineering, The University of Auckland, Auckland 1010, New Zealand
| | - Lokesh P Padhye
- Department of Civil and Environmental Engineering, Faculty of Engineering, The University of Auckland, Auckland 1010, New Zealand
| | - Srinidhi Sridharan
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Lal Singh
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Shiv Bolan
- Department of Civil and Environmental Engineering, Faculty of Engineering, The University of Auckland, Auckland 1010, New Zealand
| | - James O'Connor
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA 6001, Australia; The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia
| | - Haochen Zhao
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA 6001, Australia
| | - Sabry M Shaheen
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; King Abdulaziz University, Faculty of Meteorology, Environment, and Arid Land Agriculture, Department of Arid Land Agriculture, 21589 Jeddah, Saudi Arabia
| | - Hocheol Song
- Department of Environment, Energy and Geoinformatics, Sejong University, 98 Gunja-Dong, Guangjin-Gu, Seoul, Republic of Korea
| | - Kadambot H M Siddique
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia
| | - Hailong Wang
- Biochar Engineering Technology Research Center of Guangdong Province, School of Environmental and Chemical Engineering, Foshan University, Foshan, Guangdong 528000, China; Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, Zhejiang A&F University, Hangzhou 311300, China
| | - M B Kirkham
- Department of Agronomy, Kansas State University, Manhattan, KS 66506, United States
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; Department of Environment, Energy and Geoinformatics, Sejong University, 98 Gunja-Dong, Guangjin-Gu, Seoul, Republic of Korea; International Research Centre of Nanotechnology for Himalayan Sustainability (IRCNHS), Shoolini University, Solan 173212, Himachal Pradesh, India.
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11
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Niarchos G, Ahrens L, Kleja DB, Fagerlund F. Per- and polyfluoroalkyl substance (PFAS) retention by colloidal activated carbon (CAC) using dynamic column experiments. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 308:119667. [PMID: 35750303 DOI: 10.1016/j.envpol.2022.119667] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/16/2022] [Accepted: 06/18/2022] [Indexed: 06/15/2023]
Abstract
Developing effective remediation methods for per- and polyfluoroalkyl substance (PFAS)-contaminated soils is a substantial step towards counteracting their widespread occurrence and protecting our ecosystems and drinking water sources. Stabilisation of PFAS in the subsurface using colloidal activated carbon (CAC) is an innovative, yet promising technique, requiring better understanding. In this study, dynamic soil column tests were used to assess the retardation of 10 classical perfluoroalkyl acids (PFAAs) (C5-C11 perfluoroalkyl carboxylic acids (PFCAs) and C4, C6, C8 perfluoroalkane sulfonates (PFSAs)) as well as two alternative PFAS (6:2 and 8:2 fluorotelomer sulfonates) using CAC at 0.03% w/w, to investigate the fate and transport of PFAS under CAC treatment applications. Results showed high retardation rates for long-chain PFAS and eight times higher retardation for the CAC-treated soil compared to the non-treated reference soil for the ∑PFAS. Replacement of shorter chain perfluorocarboxylic acids (PFCAs), such as perfluoropentanoic acid (PFPeA), by longer chained PFAS was observed, indicating competition effects. Partitioning coefficients (Kd values) were calculated for the CAC fraction at ∼103-105 L kg-1 for individual PFAS, while there was a significant positive correlation (p < 0.05) between perfluorocarbon chain length and Kd. Mass balance calculations showed 37% retention of ∑PFAS in treated soil columns after completion of the experiments and 99.7% higher retention rates than the reference soil. Redistribution and elution of CAC were noticed and quantified through organic carbon analysis, which showed a 23% loss of carbon during the experiments. These findings are a step towards better understanding the extent of CAC's potential for remediation of PFAS-contaminated soil and groundwater and the limitations of its applications.
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Affiliation(s)
- Georgios Niarchos
- Department of Earth Sciences, Uppsala University, P.O. Box 256, SE-751 05, Uppsala, Sweden.
| | - Lutz Ahrens
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), P.O. Box 7050, SE-750 07, Uppsala, Sweden
| | - Dan Berggren Kleja
- Department of Soil and Environment, Swedish University of Agricultural Sciences (SLU), P. O. Box 7090, SE-750 07, Uppsala, Sweden
| | - Fritjof Fagerlund
- Department of Earth Sciences, Uppsala University, P.O. Box 256, SE-751 05, Uppsala, Sweden
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Hao S, Choi YJ, Deeb RA, Strathmann TJ, Higgins CP. Application of Hydrothermal Alkaline Treatment for Destruction of Per- and Polyfluoroalkyl Substances in Contaminated Groundwater and Soil. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:6647-6657. [PMID: 35522245 DOI: 10.1021/acs.est.2c00654] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Hydrothermal alkaline treatment (HALT) can effectively degrade per- and polyfluoroalkyl substances (PFASs) present in aqueous film-forming foam (AFFF). However, information is lacking regarding the treatment of PFASs in actual groundwater and soil from AFFF-impacted sites, especially for complex soil matrices. Given the lack of studies on direct soil treatment for PFAS destruction, we herein applied HALT to two groundwater samples and three soil samples from AFFF-impacted sites and characterized the destruction of PFASs using high-resolution mass spectrometry. Results showed that the 148 PFASs identified in all collected field samples, including 10 cationic, 98 anionic, and 40 zwitterionic PFASs, were mostly degraded to nondetectable levels within 90 min when treated with 5 M NaOH at 350 °C. The near-complete defluorination, as evidenced by fluoride release measurements, confirmed the complete destruction of PFASs. While many structures, including perfluoroalkyl carboxylic acids and polyfluorinated substances, were readily degraded, perfluoroalkyl sulfonates (PFSAs, CnF2n+1-SO3-), most notably with short chain lengths (n = 3-5), were more recalcitrant. Rates of PFSA destruction in groundwater samples were similar to those measured in laboratory water solutions, but reactions in soil were slow, presumably due to base-neutralizing properties of the soil. Further, the degradation of PFASs in groundwaters and soils was found to be a function of reaction temperature, NaOH concentration, and reaction time. These findings have important implications for the remediation of AFFF-impacted sites.
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Affiliation(s)
- Shilai Hao
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Youn Jeong Choi
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
- Department of Agronomy, Purdue University, West Lafayette, Indiana 47907, United States
| | - Rula A Deeb
- Geosyntec Consultants, Oakland, California 94607, United States
| | - Timothy J Strathmann
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Christopher P Higgins
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
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Senevirathna STMLD, Krishna KCB, Mahinroosta R, Sathasivan A. Comparative characterization of microbial communities that inhabit PFAS-rich contaminated sites: A case-control study. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:126941. [PMID: 34474371 DOI: 10.1016/j.jhazmat.2021.126941] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 08/01/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
The historic usage and discharge of per- and polyfluoroalkyl substances (PFAS) containing chemicals have produced many contaminated sites and PFAS contamination has become a global concern due to their persistence, widespread distribution, and potential adverse impacts for human and environmental health. However, there have been limited investigations on the specific behavior of bacterial communities in PFAS contaminated soils. In this study, a quantitative PCR assay and Illumina MiSeq sequencing were used to investigate the variations of bacterial communities in a regional Australian airport contaminated with PFAS. The dominate PFAS detected in soil samples was Perfluorooctanesulfonic acid (PFOS), which accounted for 82% of total PFAS and the maximum PFOS level was noted (20,947±1824 ng.PFOS/mg.Soil) at the top soil. Irrespective of the degree of PFAS contamination at different depths, the comparable percentile contribution of each PFAS was observed in soil samples. Significantly higher bacteria amplicon sequence variant (ASV) and diversity were noted in uncontaminated soil than PFAS contaminated soil. Bacterial genera Rhodanobacter and Chujaibacter were dominant in the PFAS contaminated soil. Three different bacterial genera of Alphaproteobacteria, Ambiguous taxa of Acidobacteriia, and genus Chujaibacter of Gammaproteobacteria showed a significant positive correlation and RB41, Gaiella showed a significant negative correlation with 11 different PFAS concentrations. Overall, the results presented in this study suggest that the counts and species diversity of soil microorganisms are adversely influenced by PFAS contamination.
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Affiliation(s)
- S T M L D Senevirathna
- CSU Engineering, Faculty of Business, Justice and Behavioural Sciences, Charles Sturt University, Panorama Avenue, Bathurst, NSW, Australia; Institute of Land, Water and Society, Charles Sturt University, Australia.
| | - K C Bal Krishna
- School of Engineering, Western Sydney University, Locked Bag 1797, Penrith NSW 2750, Australia
| | - Reza Mahinroosta
- CSU Engineering, Faculty of Business, Justice and Behavioural Sciences, Charles Sturt University, Panorama Avenue, Bathurst, NSW, Australia; Institute of Land, Water and Society, Charles Sturt University, Australia
| | - Arumugam Sathasivan
- School of Engineering, Western Sydney University, Locked Bag 1797, Penrith NSW 2750, Australia
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PFAS Molecules: A Major Concern for the Human Health and the Environment. TOXICS 2022; 10:toxics10020044. [PMID: 35202231 PMCID: PMC8878656 DOI: 10.3390/toxics10020044] [Citation(s) in RCA: 75] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/05/2022] [Accepted: 01/11/2022] [Indexed: 01/09/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a group of over 4700 heterogeneous compounds with amphipathic properties and exceptional stability to chemical and thermal degradation. The unique properties of PFAS compounds has been exploited for almost 60 years and has largely contributed to their wide applicability over a vast range of industrial, professional and non-professional uses. However, increasing evidence indicate that these compounds represent also a serious concern for both wildlife and human health as a result of their ubiquitous distribution, their extreme persistence and their bioaccumulative potential. In light of the adverse effects that have been already documented in biota and human populations or that might occur in absence of prompt interventions, the competent authorities in matter of health and environment protection, the industries as well as scientists are cooperating to identify the most appropriate regulatory measures, substitution plans and remediation technologies to mitigate PFAS impacts. In this review, starting from PFAS chemistry, uses and environmental fate, we summarize the current knowledge on PFAS occurrence in different environmental media and their effects on living organisms, with a particular emphasis on humans. Also, we describe present and provisional legislative measures in the European Union framework strategy to regulate PFAS manufacture, import and use as well as some of the most promising treatment technologies designed to remediate PFAS contamination in different environmental compartments.
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Uriakhil MA, Sidnell T, De Castro Fernández A, Lee J, Ross I, Bussemaker M. Per- and poly-fluoroalkyl substance remediation from soil and sorbents: A review of adsorption behaviour and ultrasonic treatment. CHEMOSPHERE 2021; 282:131025. [PMID: 34118624 DOI: 10.1016/j.chemosphere.2021.131025] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/25/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Per- and poly-fluoroalkyl substances (PFAS) are xenobiotics, present at variable concentrations in soils and groundwater worldwide. Some of the current remediation techniques being researched or applied for PFAS-impacted soils involve solidification-stabilisation, soil washing, excavation and disposal to landfill, on site or in situ smouldering, thermal desorption, ball milling and incineration. Given the large volumes of soil requiring treatment, there is a need for a more environmentally friendly technique to remove and treat PFASs from soils. Sorbents such as granular/powdered activated carbon, ion exchange resins and silicas are used in water treatment to remove PFAS. In this work, PFAS adsorption mechanisms and the effect of pore size, pH and organic matter on adsorption efficacy are discussed. Then, adsorption of PFAS to soils and sorbents is considered when assessing the viability of remediation techniques. Sonication-aided treatment was predicted to be an effective removal technique for PFAS from a solid phase, and the effect of varying frequency, power and particle size on the effectiveness of the desorption process is discussed. Causes and mitigation strategies for possible cavitation-induced particle erosion during ultrasound washing are also identified. Following soil remediation, degrading the extracted PFAS using sonolysis in a water-organic solvent mixture is discussed. The implications for future soil remediation and sorbent regeneration based on the findings in this study are given.
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Affiliation(s)
- Mohammad Angaar Uriakhil
- University of Surrey, Department of Chemical and Process Engineering, Surrey, England, GU2 7XH, UK
| | - Tim Sidnell
- University of Surrey, Department of Chemical and Process Engineering, Surrey, England, GU2 7XH, UK
| | | | - Judy Lee
- University of Surrey, Department of Chemical and Process Engineering, Surrey, England, GU2 7XH, UK
| | - Ian Ross
- Tetra Tech, Quay West at MediaCityUK, Trafford Wharf Rd, Trafford Park, Manchester, England, M17 1HH, UK
| | - Madeleine Bussemaker
- University of Surrey, Department of Chemical and Process Engineering, Surrey, England, GU2 7XH, UK.
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Feng J, Yu Q, He A, Daniel Sheng G. Accelerating Cu and Cd removal in soil flushing assisted by regulating permeability with electrolytes. CHEMOSPHERE 2021; 281:130883. [PMID: 34023758 DOI: 10.1016/j.chemosphere.2021.130883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/03/2021] [Accepted: 05/10/2021] [Indexed: 06/12/2023]
Abstract
Soil flushing is one of the common in-situ remediation technologies, in which the permeability of the soil determines its feasibility. Batch extractions showed that deionized water extracted about 20% Cu and 30% Cd from a soil. Electrolytes of 100 mmol/l NaCl, 500 mmol/l NaCl, and 167 mmol/l CaCl2 promoted the extractions to about 60% and 90%, respectively, with higher concentration and valence of cations being more effective. Presence of 100 mmol/l EDTA as a chelant further enhanced the extractions to near completion. Extractions appeared to occur concurrently via ion exchange, complexation with Cl- and predominantly chelation with EDTA. Column leaching in dynamic setups with electrolyte solutions in the presence of EDTA showed similar Cu and Cd removal degrees to the batch extractions. The permeability of soils during leaching decreased by up to 80%, decelerating time-dependent Cu and Cd removal, due to soil swelling by Na+. Electrolytes in leaching solutions well defended the permeability of soil against its decrease to as low as 3.5%, maintaining Cu and Cd removal rates. Formulating flushing solution with EDTA and proper electrolytes have advantages of not only enhancing extraction degrees but accelerating heavy metal removal from soil by regulating the permeability, with the potential to be extended to soils with high clay contents and thus low natural permeability.
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Affiliation(s)
- Jingyi Feng
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Qi Yu
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Anfei He
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China
| | - G Daniel Sheng
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China.
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17
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Mahinroosta R, Senevirathna L. The effectiveness of PFAS management options on groundwater quality in contaminated land using numerical modelling. CHEMOSPHERE 2021; 279:130528. [PMID: 33887590 DOI: 10.1016/j.chemosphere.2021.130528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
The concentrations of PFOS and PFHxS in a contaminated site in regional New South Wales, Australia, were above the human health screening values for industrial land use. In this study, the effects of different management options on the quality of groundwater were investigated through numerical modelling. At first, a complete transfer model including the main features of advection, dispersion, adsorption and decay, was developed to simulate the long-term migration of PFOS from topsoil subjected to full climate interaction for 100 years. The sorption isotherm characteristics of the contaminated soil were determined from chemical analysis using LC/MS equipment. The model results were confirmed by PFOS values measured from a monitoring well in the proximity of the site. The model showed that PFOS values in groundwater increased gradually and exceeded the guideline values for drinking water. Three management options were suggested: a do-nothing approach, cut and replacement, and immobilisation of the topsoil up to 2 m depth. The numerical models showed that although all these strategies reduced the PFOS level in the groundwater significantly, the values were still higher than the guideline values for drinking water. This was because PFOS migrated in the ground beyond the site location. The cut and replacement and immobilisation strategies ensured that the PFOS values were lower than the guideline values for soil screening, but PFOS levels in the groundwater were not necessarily lower than the guideline values for drinking water after a long time.
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Affiliation(s)
- Reza Mahinroosta
- School of Engineering, Faculty of Business, Justice and Behavioural Sciences, Charles Sturt University, Institute for Land, Water and Society, Panorama Avenue, Bathurst, NSW, Australia.
| | - Lalantha Senevirathna
- School of Engineering, Faculty of Business, Justice and Behavioural Sciences, Charles Sturt University, Institute for Land, Water and Society, Panorama Avenue, Bathurst, NSW, Australia.
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Jegatheesan V, Shu L, Rene ER, Lin TF. Challenges in environmental science/engineering and innovations in pollution prevention and resource recovery for a sustainable future. CHEMOSPHERE 2021; 276:130148. [PMID: 33730608 DOI: 10.1016/j.chemosphere.2021.130148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
| | - Li Shu
- LJS Environment, Parkville, VIC, 3052, Australia
| | - Eldon R Rene
- UNESCO-IHE Institute for Water Education, Westvest 7, 2611, AX, Delft, the Netherlands
| | - Tsair-Fuh Lin
- Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan
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Mostafazadeh F, Kilanehei F, Hassanlourad M. Experimental evaluation of self-remediation mechanism by groundwater flow in unconfined aquifers. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2021; 93:1005-1018. [PMID: 33259679 DOI: 10.1002/wer.1489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 11/01/2020] [Accepted: 11/22/2020] [Indexed: 06/12/2023]
Abstract
The main goal of this study is to investigate the effect of soil properties such as permeability on the dispersion and movement of a water dissolved contaminant in three types of soil in saturated and 2D conditions. The experimental modeling was conducted using a constructed sand box. In order to evaluate the effect of soils particle size on the distribution and self-remediation of the contaminant, three types of soil, as coarse, medium, and fine-grained sand were used. Results of experiments showed that, at the first 25% of the test time, the contaminated area reduction rate in all three specimens varies significantly, so that for the medium and coarse sand, it is 2.2 and 3 times that of fine sand, respectively. The contaminant width reduction at the first 25% of the test time was 5%, 6%, and 35% for the fine, medium, and coarse sand, respectively, while the contaminant length reduction was 13%, 18%, and 37% for the fine, medium, and coarse sand, respectively. In addition, by comparing the contaminant movement in the saturated and semi-saturated areas, it was observed that the longitudinal and transverse movement of the contaminant under the water level are almost 2.5 times of the semi-saturated area. PRACTITIONER POINTS: Reduction rate of solution area in fine, medium and coarse-grained sample are nearly convex, linear and concave-shaped, respectively. The remediation process in saturated zones is implemented in both directions with higher intensity in a shorter time than unsaturated zones. In the strip formed plumes, the volume of the self-remediation is proportional to the time intervals during the test. In the elliptic masses the self-purification amount is lower at the beginning, due to the small cross-section ending of the contamination mass.
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Affiliation(s)
- Farzad Mostafazadeh
- Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran
| | - Fouad Kilanehei
- Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran
| | - Mahmoud Hassanlourad
- Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran
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