Coupling soil washing with chelator and cathodic reduction treatment for a multi-metal contaminated soil: Effect of pH controlling

Song, Yue; Liu, Wei; Zhang, Min; Duan, Tigang; Cai, Yong

doi:10.1016/j.electacta.2023.142178

Cited by 11 publications

(2 citation statements)

References 40 publications

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“…6 b). This observation is consistent with the fact that reduced pH levels promote metal dissolution and subsequent binding with chelating agents 61 . The acidic conditions facilitated the dissolution of metals bound to the MSW compost, causing them to readily dissolve in the lower pH environment 50 .…”

Section: Resultssupporting

confidence: 87%

Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost

Khare,

Singhal,

Rallapalli

et al. 2024

Sci Rep

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Municipal solid waste compost, the circular economy's closed-loop product often contains excessive amounts of toxic heavy metals, leading to market rejection and disposal as waste material. To address this issue, the study develops a novel approach based on: (i) utilizing plant-based biodegradable chelating agent, l-glutamic acid, N,N-diacetic acid (GLDA) to remediate heavy metals from contaminated MSW compost, (ii) comparative assessment of GLDA removal efficiency at optimal conditions with conventional nonbiodegradable chelator EDTA, and (iii) enhanced pre- and post-leaching to evaluate the mobility, toxicity, and bioavailability of heavy metals. The impact of treatment variables, such as GLDA concentration, pH, and retention time, on the removal of heavy metals was investigated. The process was optimized using response surface methodology to achieve the highest removal effectiveness. The findings indicated that under optimal conditions (GLDA concentration of 150 mM, pH of 2.9, retention time for 120 min), the maximum removal efficiencies were as follows: Cd-90.32%, Cu-81.96%, Pb-91.62%, and Zn-80.34%. This process followed a pseudo-second-order kinetic equation. Following GLDA-assisted leaching, the geochemical fractions were studied and the distribution highlighted Cd, Cu, and Pb's potential remobilization in exchangeable fractions, while Zn displayed integration with the compost matrix. GLDA-assisted leaching and subsequent fractions illustrated transformation and stability. Therefore, this process could be a sustainable alternative for industrial applications (agricultural fertilizers and bioenergy) and social benefits (waste reduction, urban landscaping, and carbon sequestration) as it has controlled environmental footprints. Hence, the proposed remediation strategy, chemically assisted leaching, could be a practical option for extracting heavy metals from MSW compost, thereby boosting circular economy.

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Section: Resultssupporting

confidence: 87%

Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost

Khare,

Singhal,

Rallapalli

et al. 2024

Sci Rep

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“…Some studies have shown that heavy metals are soluble in acidic environments, have higher mobility, and can enter groundwater through media infiltration [70,71]. When the soil pH is alkaline, most of the heavy metals exist in the form of low-solubility salt, and the mobility of heavy metals is low, resulting in the enrichment of heavy metals in the soil [72,73]. On the other hand, some studies have shown that heavy metals in traffic, industrial emissions, and coal combustion are highly correlated with NO 2 and SO 2 [74,75], which indirectly affect the accumulation of heavy metals through precipitation into the soil.…”

Section: Response Relationship Between Sources and Soil Heavy Metalsmentioning

confidence: 99%

Source Apportionment of Soil Heavy Metal(Loid)s in Farmland Using Diverse Models: A Comparative Assessment in the Yellow River Delta

Huang

Wang

et al. 2023

JMSE

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The rapid development of industrialization and urbanization has posed serious challenges for coastal farmland ecosystems. Source apportionment of soil heavy metals is an effective way for the detection of non-point source pollution in farmland to help support the high-quality development of coastal agriculture. To this end, 113 surface soil samples were collected in the coastal delta of China, and the contents of As, Cd, Cr, Cu, Ni, Pb, and Zn were determined. A variety of models were integrated to apportion the source of soil heavy metals, including positive matrix factorization (PMF), geographical detector (GD), eXtreme gradient boosting (XGBoost), and structural equation modeling (SEM). The result of PMF models revealed that there was collinearity between various heavy metals, and the same heavy metal may have a mixed source. The XGBoost model analysis indicated that there were significant non-linear relationships between soil heavy metals and source factors. A synergy between air quality and human activity factors was the key source of heavy metal that entered the study area, based on the results of the GD. Furthermore, the input path effect of heavy metals in the soil of the study area was quantified by SEM. The balance of evidence from the above models showed that air quality (SO2 and NO2) and factories in the study area had the greatest impacts on Cd, Cr, and Zn. Natural sources were dominant for Pb, while As, Cu, and Ni were contributed by soil parent material and factories. The above results led to the conclusion that there was a cycle path in the study area that continuously promoted the migration and accumulation of heavy metals in farmland soil; that is, the heavy metals discharged during oil exploitation and smelting entered the atmosphere and then accumulated in the farmland soil through precipitation, atmospheric deposition, and other paths. In this study, it is shown that a variety of models can be used to more comprehensively assess the sources of soil heavy metals. This approach can provide effective support for the rapid prevention and decision-making management of soil heavy metal pollution in coastal areas.

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Removal of Typical Heavy Metals from Soil by the Synergistic Interaction between Microbubbles and Washing Agents: Experiments, Influences, and Mechanisms

Ou,

Wang,

Gao

et al. 2024

Water Air Soil Pollut

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Coupling soil washing with chelator and cathodic reduction treatment for a multi-metal contaminated soil: Effect of pH controlling

Cited by 11 publications

References 40 publications

Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost

Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost

Source Apportionment of Soil Heavy Metal(Loid)s in Farmland Using Diverse Models: A Comparative Assessment in the Yellow River Delta

Removal of Typical Heavy Metals from Soil by the Synergistic Interaction between Microbubbles and Washing Agents: Experiments, Influences, and Mechanisms

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