Comparison of Remediation Mechanism of Heavy Metal–Contaminated Soil by Combined Leaching and Two-Step Leaching

Zhang, Shuqin; Zhang, Xu; Zhang, Kening; Yuan, Baoling; Ren, Dajun; Zhang, Xiaoqing

doi:10.1007/s11270-023-06394-6

Cited by 4 publications

(2 citation statements)

References 109 publications

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“…In terms of the surface strength, both treatment methods demonstrate an increase in the samples' surface strength, albeit to varying degrees. This variation can be attributed to the mechanism of EICP technology treatment, where urease catalyzes urea to generate carbonate ions, which then interact with the calcium source and high-valence cations in the contaminated loess to form carbonate precipitation [33]. This process enhances the cohesion of loose soil particles, leading to the formation of a robust surface shell and ultimately boosting the surface strength.…”

Section: Comparison Of Eicp Technology and Eicp Technology Without Ca...mentioning

confidence: 99%

Feasibility Study of Applying Enzyme-Induced Carbonate Precipitation (EICP) without Calcium Source for Remediation of Lead-Contaminated Loess

Zhang,

Zhang

2024

Buildings

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To assess the long-term stability of lead-contaminated loess treated with calcium-free Enzyme-Induced Carbonate Precipitation (EICP) technology while avoiding significant soil strength increases, various parameters such as the pH value, heavy metal ion leaching rate, and soil heavy metal speciation were evaluated. This study investigated the remediated soil’s stability under complex environmental conditions, including dry–wet cycles and acid rain leaching. The intrinsic mechanisms were elucidated through the Zeta potential, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses. The results showed that compared to the untreated lead-contaminated loess, the surface strength of the loess treated with EICP technology increased by 3.86 times, with a 1.47-fold increase observed with the calcium-free EICP treatment. Carbonate precipitation improved the erosion resistance by adsorbing or coating fine particles and forming bridging connections with coarse particles. As the number of dry–wet cycles increased, the soil pH gradually decreased but remained above 8.25. The heavy metal leaching rate increased with the leaching cycles until reaching a plateau. The acid rain influence showed a decrease in the Pb2+ content in the leachate as the acid rain solution pH increased, meeting hazardous waste disposal regulations. These findings offer new insights for improving heavy metal-contaminated loess site remediation and understanding the underlying geochemical mechanisms.

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Section: Comparison Of Eicp Technology and Eicp Technology Without Ca...mentioning

confidence: 99%

Feasibility Study of Applying Enzyme-Induced Carbonate Precipitation (EICP) without Calcium Source for Remediation of Lead-Contaminated Loess

Zhang,

Zhang

2024

Buildings

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“…However, interactions between contaminated liquids and loess can modify pore structure, deteriorate soil engineering properties, and negatively impact the performance of anti-fouling barriers [4]. Understanding these mechanisms and implementing strategies to improve heavy metal-contaminated soil are crucial for ensuring the safety and longevity of geotechnical engineering projects [5].…”

Section: Introductionmentioning

confidence: 99%

Feasibility of Microbially Induced Carbonate Precipitation to Enhance the Internal Stability of Loess under Zn-Contaminated Seepage Conditions

He,

Guo,

Zhang

2024

Buildings

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Loess is widely distributed in Northwestern China and serves as the preferred engineering construction material for anti-fouling barriers. Heavy metal contamination in soil presents significant challenges to the engineering safety of vulnerable loess structures. Hence, there is an urgent need to investigate the impact of heavy metal ions on their percolation performance. In order to investigate the effectiveness of microbially induced carbonate precipitation (MICP) using Sporosarcina pasturii (CGMCC1.3687) bacteria in reducing internal seepage erosion, a saturated permeability test was conducted on reshaped loess under constant water head saturation conditions. The response of loess to deionized water (DW) and ZnCl2 solution seepages was analyzed by monitoring changes in cation concentration over time, measuring Zeta potential, and using scanning electron microscopy (SEM). The results indicate that the hydrolysis of Zn2+ creates an acidic environment, leading to the dissolution of carbonate minerals in the loess, which enhances its permeability. The adsorption of Zn2+ ions and the resulting diffusion double-layer (DDL) effect reduce the thickness of the diffusion layer and increase the number of free water channels. Additionally, the permeability of loess exposed to ZnCl2 solution seepage significantly increased by 554.5% compared to loess exposed to deionized water (DW) seepage. Following the seepage of ZnCl2 solutions, changes in micropore area ratio were observed, decreasing by 48.80%, while mesopore areas increased by 23.9%. MICP treatment helps reduce erosion and volume shrinkage in contaminated loess. Carbonate precipitation enhances the erosion resistance of contaminated loess by absorbing or coating fine particles and creating bridging connections with coarse particles. These research results offer new perspectives on enhancing the seepage properties of saturated loess in the presence of heavy metal erosion and the geochemical mechanisms involved.

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Study on the enhancement of citric acid chemical leaching of contaminated soil by modified nano zero-valent iron

Zhang,

Zhou,

Tang

et al. 2024

Environ Geochem Health

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Comparison of Remediation Mechanism of Heavy Metal–Contaminated Soil by Combined Leaching and Two-Step Leaching

Cited by 4 publications

References 109 publications

Feasibility Study of Applying Enzyme-Induced Carbonate Precipitation (EICP) without Calcium Source for Remediation of Lead-Contaminated Loess

Feasibility Study of Applying Enzyme-Induced Carbonate Precipitation (EICP) without Calcium Source for Remediation of Lead-Contaminated Loess

Feasibility of Microbially Induced Carbonate Precipitation to Enhance the Internal Stability of Loess under Zn-Contaminated Seepage Conditions

Study on the enhancement of citric acid chemical leaching of contaminated soil by modified nano zero-valent iron

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