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Oh MS, Namgung G, Kim H. Enhanced air sparging for groundwater remediation using alginate gel-based removable hydraulic barriers. JOURNAL OF CONTAMINANT HYDROLOGY 2024; 260:104258. [PMID: 38064800 DOI: 10.1016/j.jconhyd.2023.104258] [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: 07/31/2023] [Revised: 10/10/2023] [Accepted: 10/20/2023] [Indexed: 01/05/2024]
Abstract
The objective of this study was to investigate the effect of a removable physical barrier on the air sparging performance using a lab-scale aquifer model was investigated. The barrier was installed in water-saturated porous media, prior to the air sparging, by injecting calcium chloride aqueous solution into the aquifer with pre-applied alginate solution. Changes in the air flow direction and air flux at the media surface during air sparging were evaluated. With a hydrogel barrier set at the center of the media, the airflow detoured the barrier resulting in a bimodal air flux distribution at the media surface. While employing two gel-formed barriers positioned away from the media's center, the airflow concentrated specifically on the gap between the barriers. The hydrogel was successfully removed using a sodium bicarbonate solution (1.0 mol/L). Using the hydrogel barrier, the performance of air sparging was significantly enhanced for removing contaminants [tetrachloroethene (PCE) and n-hexane mixture] due to increased air flux; 9.8% of PCE applied (7.8 g) was removed during 120 min air sprging for the gel barrier system whereas no PCE was removed for the control. Alginate gel did not show significant sorption capacity for PCE. It was stable in the contaminant up to 68 days with reasonable loss of its mass. Findings of this study present a promising option for air sparging process specifically targeting the contaminant source zone in the aquifer.
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Affiliation(s)
- Min-Su Oh
- Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252, Republic of Korea
| | - Geon Namgung
- Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252, Republic of Korea
| | - Heonki Kim
- Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252, Republic of Korea.
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Yao M, Yuan Q, Qu D, Liu W, Zhao Y, Wang M. Effects of airflow rate distribution and nitrobenzene removal in an aquifer with a low-permeability lens during surfactant-enhanced air sparging. JOURNAL OF HAZARDOUS MATERIALS 2022; 437:129383. [PMID: 35728315 DOI: 10.1016/j.jhazmat.2022.129383] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 06/01/2022] [Accepted: 06/12/2022] [Indexed: 06/15/2023]
Abstract
The application of surfactant-enhanced air sparging (SEAS) in heterogeneous aquifers has received increasing attention. In this study, a two-dimensional laboratory visualization device was used to study the migration and distribution mechanism of airflow and the nitrobenzene removal effect in an aquifer with a low-permeability lens during AS and SEAS. Experimental results showed that the surfactant significantly reduced the blocking effect of the geological interface on airflow, and the ΔPe (the air entry pressure difference between the background media and the lens) value of the geological interface decreased from 1.1 kPa to 0.3 kPa when the surfactant concentration was 800 mg/L. When the surfactant injection location was at the center of the lens and the injection volume was 1 PV (pore volume of the lens), part of the airflow entered the lens through its below interface, which clearly improved the nitrobenzene removal inside and above the lens compared with AS remediation. However, when SEAS remediation was 24 h, the surfactant redistribution caused by air sparging resulted in the airflow entering the lens to bypass the lens again, which changed the spatial distribution of airflow rate and was not conducive to the continuous removal of nitrobenzene inside the lens.
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Affiliation(s)
- Meng Yao
- School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China; National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China.
| | - Qian Yuan
- School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China
| | - Dan Qu
- Baohang Environment Co.Ltd., Beijing 100036, China
| | - Wenjun Liu
- School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China
| | - Yongsheng Zhao
- National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China.
| | - Mingxin Wang
- School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China.
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Yao M, Bai J, Chang Y, Qin C, Li F, Yang X, Zhao Y. Effects of air flowrate distribution and benzene removal in heterogeneous porous media during air sparging remediation. JOURNAL OF HAZARDOUS MATERIALS 2020; 398:122866. [PMID: 32464561 DOI: 10.1016/j.jhazmat.2020.122866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/21/2020] [Accepted: 04/25/2020] [Indexed: 06/11/2023]
Abstract
The decrease of remediation effect during air sparging (AS) remediation in heterogeneous porous media has attracted increasing attention. In this study, an improved light transmission visualization method was used to investigate the air accumulation, migration and flowrate distribution in benzene-contaminated heterogeneous porous media during AS. Experimental results indicated that the benzene removal rate in the porous media was mainly controlled by air flowrate distribution which could be used as a major factor to evaluate the remediation effect. Visualization of air migration showed that air accumulation occurred below the geologic heterogeneous interface when ΔPe > 0 kPa (ΔPe: the air entry pressure difference of the media above and below the interface), and the accumulation thickness and length presented exponential decay increases with increasing ΔPe and air injection rates. Air flowrate was monitored by gas flow sensors, and the flowrate distributions were found as Gaussian distribution when ΔPe ≤ 0 kPa, trapezoidal distribution when 0 <ΔPe< 0.3 kPa and fingered distribution when ΔPe ≥ 0.3 kPa. Fingered distribution of air flowrate resulted in extremely nonuniform benzene removal above the interface and reduced the overall benzene removal rate. These findings reveal the reasons for the poor performance of AS remediation in heterogeneous porous media, leading to a better understanding of the remediation mechanisms in heterogeneous aquifer.
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Affiliation(s)
- Meng Yao
- National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun,130021, China; Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun,130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, China.
| | - Jing Bai
- National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun,130021, China; Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun,130021, China
| | - Yuehua Chang
- National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun,130021, China; Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun,130021, China
| | - Chuanyu Qin
- National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun,130021, China; Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun,130021, China
| | - Fengyu Li
- Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun,130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, China
| | - Xinru Yang
- National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun,130021, China; Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun,130021, China
| | - Yongsheng Zhao
- National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun,130021, China; Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun,130021, China.
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Zingaretti D, Lominchar MA, Verginelli I, Santos A, Baciocchi R. Humic acids extracted from compost as amendments for Fenton treatment of diesel-contaminated soil. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:22225-22234. [PMID: 32146675 DOI: 10.1007/s11356-020-08221-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/24/2020] [Indexed: 06/10/2023]
Abstract
In this study, we investigate the performance of a Fenton-like process carried out adding as amendments humic acids extracted from compost obtained from organic wastes. Namely, Fenton-like lab-scale tests with different dosages of the extracted humic acids and traditional stabilizing agent (KH2PO4) were performed on a diesel-contaminated soil collected in a former gasoline station. The performed tests showed a beneficial effect of the extracted humic acids on the hydrogen peroxide stability. Namely, the H2O2 lifetime in the tests carried out without the addition of any amendments proved to be quite limited, resulting equal to around 1 h. The adoption of the extracted humic acids alone entailed a limited increase of the hydrogen peroxide stability that anyhow was detected in solution for 24 h using 10 g/L of extracted HA. When the humic acids (10 g/L) were used in combination with KH2PO4 (8.2 g/L), the hydrogen peroxide lifetime increased up to around 150 h. A beneficial effect of the humic acids extracted from compost for a Fenton-like process was also observed in terms of diesel removal. Namely, without any amendment, a contaminant removal of around 55% was observed. Using KH2PO4 or HA alone, the contaminant removal raised up to around 75% while using the traditional stabilizer together with the humic acids extracted from compost, it was possible to remove up to 90% of the initial diesel content of the soil.
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Affiliation(s)
- Daniela Zingaretti
- Department of Civil Engineering and Computer Science Engineering, Laboratory of Environmental Engineering, University of Rome "Tor Vergata", Rome, RM, Italy.
| | | | - Iason Verginelli
- Department of Civil Engineering and Computer Science Engineering, Laboratory of Environmental Engineering, University of Rome "Tor Vergata", Rome, RM, Italy
| | - Aurora Santos
- Chemical Engineering Department, University Complutense of Madrid, Spain, Madrid, Spain
| | - Renato Baciocchi
- Department of Civil Engineering and Computer Science Engineering, Laboratory of Environmental Engineering, University of Rome "Tor Vergata", Rome, RM, Italy
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