Editorial

3 pages, 163 KiB

Open AccessEditorial

Environmental Restoration of Metal-Contaminated Soils

by Fulvia Chiampo and Massimo Zacchini

Appl. Sci. 2021, 11(22), 10805; https://doi.org/10.3390/app112210805 - 16 Nov 2021

Cited by 3 | Viewed by 1128

The growing industrialization of the last two centuries has improved life to a great extent in the countries where it occurred [...] Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

Research

Jump to: Editorial, Review

12 pages, 6730 KiB

Open AccessArticle

A Study on the Flow Characteristics of Copper Heavy Metal Microfluidics with Hydrophobic Coating and pH Change

by Jung-Geun Han, Dongho Jung, Jong-Young Lee, Dongchan Kim and Gigwon Hong

Appl. Sci. 2021, 11(10), 4328; https://doi.org/10.3390/app11104328 - 11 May 2021

Cited by 1 | Viewed by 1407

Abstract

The present study purpose was to identify the flow characteristics of the drainage filter considering the characteristics of the landfill site, and to study the basic technology for efficient remediation of heavy metals. To this end, copper heavy metal was selected in consideration [...] Read more.

The present study purpose was to identify the flow characteristics of the drainage filter considering the characteristics of the landfill site, and to study the basic technology for efficient remediation of heavy metals. To this end, copper heavy metal was selected in consideration of landfill characteristics, and a study on flow characteristics was conducted using hydrophobic coated capillary tubes and microparticles. It was confirmed that the flow rate decreased as the pH increased at the hydrophobic surface, and pH 4, 6, and 8 flowed similarly in the center of the capillary tube, but decreased at pH 10. In the bottom part, it moved at the slowest speed of 1~4 μm/s and middle of center moved 17~25 μm/s. There was little change in flow in the CFD (Computational Fluid Dynamics) numerical analysis considering the surface contact angle, which is a hydrophobic characteristic, and the velocity coefficient was presented by regression analysis through the experimental results. In this way, the current study will be a basic examination of the selective remediation process of pH on hydrophobic coated surfaces. Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

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10 pages, 4148 KiB

Open AccessArticle

Testing of Natural Sorbents for the Assessment of Heavy Metal Ions’ Adsorption

by Vera Yurak, Rafail Apakashev, Alexey Dushin, Albert Usmanov, Maxim Lebzin and Alexander Malyshev

Appl. Sci. 2021, 11(8), 3723; https://doi.org/10.3390/app11083723 - 20 Apr 2021

Cited by 16 | Viewed by 2276

Abstract

Nowadays, the sorption-oriented approach is on the agenda in the remediation practices of lands contaminated with heavy metals. The current growing quantity of research accounts for different sorbents. However, there is still a lack of studies utilizing the economic criteria. Therefore, to ensure [...] Read more.

Nowadays, the sorption-oriented approach is on the agenda in the remediation practices of lands contaminated with heavy metals. The current growing quantity of research accounts for different sorbents. However, there is still a lack of studies utilizing the economic criteria. Therefore, to ensure a wide application of opportunities, one of the necessary requirements is their economic efficiency in use. By utilizing these criteria, this manuscript researches the generally accepted natural sorbents for the assessment of heavy metal ions’ adsorption, such as peat, diatomite, vermiculite and their mixtures in different proportions and physical shapes. The methodological base of the study consists of the volumetric (titrimetric) method, X-ray fluorescence spectrometry and atomic absorption spectrometry. Experimental tests show a certain decline in the efficiency of heavy metal ions’ adsorption from aqueous salt solutes as follows: granular peat–diatomite > large-fraction vermiculite > medium-fraction vermiculite > non-granular peat–diatomite > diatomite. Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

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14 pages, 1155 KiB

Open AccessFeature PaperArticle

Different Approaches for Incorporating Bioaccessibility of Inorganics in Human Health Risk Assessment of Contaminated Soils

by Daniela Zingaretti and Renato Baciocchi

Appl. Sci. 2021, 11(7), 3005; https://doi.org/10.3390/app11073005 - 27 Mar 2021

Cited by 8 | Viewed by 2173

Abstract

Ingestion of soil represents one of the critical exposure pathways in the human health risk assessment (HHRA) framework at sites contaminated by inorganic species, especially for residential scenarios. HHRA is typically carried out through starting from the so-called “total concentration”, which is estimated [...] Read more.

Ingestion of soil represents one of the critical exposure pathways in the human health risk assessment (HHRA) framework at sites contaminated by inorganic species, especially for residential scenarios. HHRA is typically carried out through starting from the so-called “total concentration”, which is estimated from the fraction of inorganic species extracted from the soil using standardized approaches, i.e., microwave acid extraction. Due to the milder conditions, a smaller portion of the inorganics present in the soil is actually dissolved in the gastro-intestinal tract (bioaccessible fraction), and afterward reaches the bloodstream, exerting an effect on human health (bioavailable fraction). Including bioaccessibility in HHRA could then allow for the achievement of a more realistic assessment than using the total concentration. In this paper, the bioaccessible concentration of different inorganics in soil samples collected from a firing range was estimated by applying two in vitro tests, i.e., the Unified Barge Method (UBM) and the Simple Bioaccessibility Extraction Test (SBET). Moreover, different options for incorporating bioaccessibility in HHRA for the estimation of the cleanup goals were also applied and discussed. Despite the notable differences in terms of reagents and procedure between the two methods, the obtained results were quite close, with the SBET method providing slightly higher values. The role of the soil particle size distribution on the calculation of the cleanup goals accounting for bioaccessibility is also discussed. Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

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12 pages, 2750 KiB

Open AccessFeature PaperArticle

Enhanced Electrokinetic Remediation for the Removal of Heavy Metals from Contaminated Soils

by Claudio Cameselle, Susana Gouveia and Adrian Cabo

Appl. Sci. 2021, 11(4), 1799; https://doi.org/10.3390/app11041799 - 18 Feb 2021

Cited by 33 | Viewed by 3484

Abstract

The electrokinetic remediation of an agricultural soil contaminated with heavy metals was studied using organic acids as facilitating agents. The unenhanced electrokinetic treatment using deionized water as processing fluid did not show any significant mobilization and removal of heavy metals due to the [...] Read more.

The electrokinetic remediation of an agricultural soil contaminated with heavy metals was studied using organic acids as facilitating agents. The unenhanced electrokinetic treatment using deionized water as processing fluid did not show any significant mobilization and removal of heavy metals due to the low solubilization of metals and precipitation at high pH conditions close to the cathode. EDTA and citric acid 0.1 M were used as facilitating agents to favor the dissolution and transportation of metals. The organic acids were added to the catholyte and penetrated into the soil specimen by electromigration. EDTA formed negatively charged complexes. Citric acid formed neutral metal complexes in the soil pH conditions (pH = 2–4). Citric acid was much more effective in the dissolution and transportation out of the soil specimen of complexed metals. In order to enhance the removal of metals, the concentration of citric acid was increased up to 0.5 M, resulting in the removal of 78.7% of Cd, 78.6% of Co, 72.5% of Cu, 73.3% of Zn, 11.8% of Cr and 9.8% of Pb. Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

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15 pages, 1681 KiB

Open AccessFeature PaperArticle

Assessment and Mitigation of Heavy Metals Uptake by Edible Vegetables Grown in a Turin Contaminated Soil Used as Vegetable Garden

by Elisa Gaggero, Paola Calza, Debora Fabbri, Anna Fusconi, Marco Mucciarelli, Giorgio Bordiglia, Ornella Abollino and Mery Malandrino

Appl. Sci. 2020, 10(13), 4483; https://doi.org/10.3390/app10134483 - 29 Jun 2020

Cited by 4 | Viewed by 1902

Abstract

In this study we evaluated the concentration of 22 elements, namely Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, K, La, Mg, Mn, Na, Ni, P, Pb, Sr, Ti, V, Zn, and their uptake by edible plants in soils collected in [...] Read more.

In this study we evaluated the concentration of 22 elements, namely Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, K, La, Mg, Mn, Na, Ni, P, Pb, Sr, Ti, V, Zn, and their uptake by edible plants in soils collected in a green urban area. The results highlighted a high yield of those heavy metals typical for anthropic pollution, such as Pb, Zn, Cu, Ba and Co, likely due to the intensive vehicular traffic. The uptake of metals by edible plants was analyzed on two broadleaf plants, Lactuca sativa and Brassica oleracea, grown in this soil and in an uncontaminated Turin soil in a growth chamber with and without the addition of a soil improver, provided by a local Organic Waste Treatment Plant. The subsequent analysis of their aerial part and roots highlighted the absorption of the main potentially toxic elements (PTEs) by the vegetables grown in the contaminated soil, whereas their concentration was lower if cultivated in the comparison soil, which was free of pollutants. The use of a soil amendment did not decrease the uptake of PTEs by Lactuca sativa and Brassica oleracea, but it caused a strong reduction in their translocation from the roots to the edible part, which consisted of the aerial part. Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

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13 pages, 1797 KiB

Open AccessArticle

The Potential Effectiveness of Biochar Application to Reduce Soil Cd Bioavailability and Encourage Oak Seedling Growth

by Elnaz Amirahmadi, Seyed Mohammad Hojjati, Claudia Kammann, Mohammad Ghorbani and Pourya Biparva

Appl. Sci. 2020, 10(10), 3410; https://doi.org/10.3390/app10103410 - 14 May 2020

Cited by 30 | Viewed by 2920

Abstract

Today, it is very important to protect plants in soils contaminated with metals. We investigated the behavior of cadmium during the establishment of oak seedlings (Quercus castaneifolia C.A. Mey.) under biochar influence. This study was conducted in pots with loamy soil. Cadmium [...] Read more.

Today, it is very important to protect plants in soils contaminated with metals. We investigated the behavior of cadmium during the establishment of oak seedlings (Quercus castaneifolia C.A. Mey.) under biochar influence. This study was conducted in pots with loamy soil. Cadmium was added to soil at 0, 10, 30, and 50 mg per kg of soil, indicated by Control, Cd10, Cd30 and Cd50. Biochar was produced at 500–550 °C from rice husk and added at 1, 3, and 5% (wt/wt) levels, indicated by B1, B3, B5, and mixed with soil at planting in three replications. Generally, increasing biochar rates had significant effects on seedling height, diameter, and biomass. This coincided with Cd immobilization in the contaminated soil which reflects a decrease in Cd concentrations in the plant bioavailability of Cd. The tolerance index increased significantly, by 40.9%, 56%, and 60.6% in B1, B3, and B5 with Cd50, respectively, compared to polluted soil. The percent of Cd removal efficiency for Cd50 was 21%, 47%, and 67% in B1, B2, and B5, respectively. Our study highlights that biochar can reduce Cd bioavailability and improve the growth of oak seedlings in contaminated soil. Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

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Review

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23 pages, 1845 KiB

Open AccessFeature PaperReview

Remediation of Metal/Metalloid-Polluted Soils: A Short Review

by Carla Maria Raffa, Fulvia Chiampo and Subramanian Shanthakumar

Appl. Sci. 2021, 11(9), 4134; https://doi.org/10.3390/app11094134 - 30 Apr 2021

Cited by 64 | Viewed by 9184

Abstract

The contamination of soil by heavy metals and metalloids is a worldwide problem due to the accumulation of these compounds in the environment, endangering human health, plants, and animals. Heavy metals and metalloids are normally present in nature, but the rise of industrialization [...] Read more.

The contamination of soil by heavy metals and metalloids is a worldwide problem due to the accumulation of these compounds in the environment, endangering human health, plants, and animals. Heavy metals and metalloids are normally present in nature, but the rise of industrialization has led to concentrations higher than the admissible ones. They are non-biodegradable and toxic, even at very low concentrations. Residues accumulate in living beings and become dangerous every time they are assimilated and stored faster than they are metabolized. Thus, the potentially harmful effects are due to persistence in the environment, bioaccumulation in the organisms, and toxicity. The severity of the effect depends on the type of heavy metal or metalloid. Indeed, some heavy metals (e.g., Mn, Fe, Co, Ni) at very low concentrations are essential for living organisms, while others (e.g., Cd, Pb, and Hg) are nonessential and are toxic even in trace amounts. It is important to monitor the concentration of heavy metals and metalloids in the environment and adopt methods to remove them. For this purpose, various techniques have been developed over the years: physical remediation (e.g., washing, thermal desorption, solidification), chemical remediation (e.g., adsorption, catalysis, precipitation/solubilization, electrokinetic methods), biological remediation (e.g., biodegradation, phytoremediation, bioventing), and combined remediation (e.g., electrokinetic–microbial remediation; washing–microbial degradation). Some of these are well known and used on a large scale, while others are still at the research level. The main evaluation factors for the choice are contaminated site geology, contamination characteristics, cost, feasibility, and sustainability of the applied process, as well as the technology readiness level. This review aims to give a picture of the main techniques of heavy metal removal, also giving elements to assess their potential hazardousness due to their concentrations. Full article

(This article belongs to the Special Issue Environmental Restoration of Metal-Contaminated Soils)

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