scholarly journals Novel and Eco-Friendly Washing Agents to Remove Heavy Metals from Soil by Soil Washing

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Zygmunt Mariusz Gusiatin

Soil washing is a remediation technology that can efficiently remove heavy metals from soil and decrease environmental risk. Due to the negative effect of conventional washing agents on soil quality, their replacement with novel, eco-friendly agents is necessary. This paper gives a basic presentation of the most promising washing agents that have high potential to be used at field scale: biodegradable chelators, biosurfactants, plant extracts, and dissolved organic matter including soluble low-weight organic matter and soluble humic substances. The main advantages of these novel agents are highlighted

2021 ◽  
Author(s):  
Marina Dinu

<p>The reactions of toxicants with organic substances of a humic nature are complex and depend on many geochemical factors. Differences in the mechanisms of the selected toxicants binding with organic natural substances of various natural waters - atmospheric precipitation, lake waters (acidic and alkaline), lysimetric waters are especially interesting. Due to significant concentration differences, features of functional groups and size distribution of components, the inactivation features of humic substances are selective and highly variable. We studied the waters of an acid lake near the city of Valday (Valday National Park, conditionally a background lake) and alkaline lake Valday (city of Valday, local technogenic influence). Near each lake there was a sediment collector (a container for collecting atmospheric precipitation) and a lysimeter (a container under the soil for collecting soil moisture) under the humus horizon (about 20 cm). Particular attention was paid to soil (lysimetric) waters with varying degrees of anthropogenic impact. We considered the behavior of a large group of heavy metals, as well as benzopyrene. To assess the composition and qualitative features of organic substances, gas chromatography-mass spectrometric methods of analysis were used. Chromatographic methods were used to assess the molecular weight distribution of the components. Possible reaction mechanisms were studied by IR spectral methods. Evaluation of the reactivity of organic substances was carried out by the methods of dynamic light scattering (zeta potential, MM, size) using the "Zeta-sizer nano". In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. For separation, exchange technique and fluorometric evaluations were used. We conducted research in the period 2015-2020, sampling was carried out in spring, summer, autumn. Thus, we studied the circulation (in miniature) of changes in the protective properties of humic substances, depending on a large number of factors.</p>


Author(s):  
Stanislav Dushkin

The article discusses the issues of reducing the level of technogenic safety of the negative impact of urban wastewater sludge on the environment by removing heavy metals using humic substances. It is noted that the technogenic and ecological problem requires an urgent solution through the formation of new effective methods of treatment (neutralization and dehydration) and further disposal of urban wastewater sludge. Silt sites are a source of pollution of soil, groundwater and surface water object and air. A new method for removing heavy metals from municipal wastewater sludge using humic substances has been developed. It was found that humic substances have a sorption capacity in relation to heavy metals. As a reagent for removing heavy metals from urban wastewater sludge, it is proposed to use the product of processing lignite and peat with alkali using a carbon-alkali reagent, which makes it possible to reduce the concentration of heavy metals to such concentrations that the sludge can be used as fertilizer in agriculture.


Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1458
Author(s):  
Carlos Boente ◽  
Carlos Sierra ◽  
Eduardo Rodríguez-Valdés ◽  
Diego Baragaño ◽  
José Luis Rodríguez Gallego ◽  
...  

Soil washing is a remediation technology based on the adaptation of techniques habitually used in mineral processing to recover contaminants from polluted soils. Its main scope is the reduction of the total volume of contaminated soil, which could later be treated by biological, chemical, or thermal procedures. Since the contaminants are usually associated to the soil finer fractions, direct classification is the most widely employed technique. Moreover, other procedures, such as indirect classification, density and magnetic separation, as well as froth flotation are also extended. Soil washing is usually applied by means of on-site mobile plants which are located in the study sites. However, previously to these field applications, a detailed soil characterization and some trials are required in order to optimize the process. In this work, soils affected by heavy metals as a result of mining, metallurgical, and industrial activities are evaluated and pilot-scale treated. The diversity of soils and residues treated, together with the variety of the methodologies employed enabled the elaboration of a general feasibility protocol.


2011 ◽  
Vol 49 (No. 12) ◽  
pp. 565-571 ◽  
Author(s):  
G. Barančíková ◽  
J. Makovníková

Mobile and potentially mobile forms of heavy metals are probably one of the most important toxic hazards in the environment. Besides pH, which is a factor influencing the mobility/availability of heavy metals to the greatest extent, the content and mainly the quality of soil organic matter play a very important role in the evaluation of heavy metal behaviour in the environment. The fraction of metals bound to organic compounds is exclusively associated with humic substances and particularly with humic acids (HA). A relationship between the parameters reflecting the actual structure of humic acids and mobile or potentially mobile fractions of heavy metals was studied in 12 soil localities representing different soil types. It can be stated on the basis of the acquired data that heavy metals tend to form complexes with soil organic matter that are different for each metal. The results suggest that copper is bound mainly in an unavailable form (significant correlations of fraction IV with HA parameters) and cadmium prefers exchangeable forms (significant correlations of fraction I with HA parameters) and is more available. It can be assumed on the basis Spearman’s correlations that mobile fractions of cadmium are predominantly bound to the aliphatic part of humic substances, and copper prefers strong bonds to humic acids with a high degree of humification.


2015 ◽  
Vol 5 (3) ◽  
pp. 1-6 ◽  
Author(s):  
Zainab Siddiqui ◽  
◽  
S.M Ali Jawaid ◽  
Sandeep Vishen ◽  
Shreya Verma ◽  
...  

1995 ◽  
Vol 32 (9-10) ◽  
pp. 85-94 ◽  
Author(s):  
Michael O. Angelidis

The impact of the urban effluents of Mytilene (Lesvos island, Greece) on the receiving coastal marine environment, was evaluated by studying the quality of the city effluents (BOD5, COD, SS, heavy metals) and the marine sediments (grain size, organic matter, heavy metals). It was found that the urban effluents of Mytilene contain high organic matter and suspended particle load because of septage discharge into the sewerage network. Furthermore, although the city does not host important industrial activity, its effluents contain appreciable metal load, which is mainly associated with the particulate phase. The city effluents are discharged into the coastal marine environment and their colloidal and particulate matter after flocculation settles to the bottom, where is incorporated into the sediments. Over the years, the accumulation of organic matter and metals into the harbour mud has created a non-point pollution source in the relatively non-polluted coastal marine environment of the island. Copper and Zn were the metals which presented the higher enrichment in the sediments of the inner harbour of Mytilene.


Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1067
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Romualda Bejger ◽  
Guillaume Debaene ◽  
Bożena Smreczak

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.


Biomolecules ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 448
Author(s):  
Mahrous Awad ◽  
Zhongzhen Liu ◽  
Milan Skalicky ◽  
Eldessoky S. Dessoky ◽  
Marian Brestic ◽  
...  

Heavy metals (HMs) toxicity represents a global problem depending on the soil environment’s geochemical forms. Biochar addition safely reduces HMs mobile forms, thus, reducing their toxicity to plants. While several studies have shown that biochar could significantly stabilize HMs in contaminated soils, the study of the relationship of soil properties to potential mechanisms still needs further clarification; hence the importance of assessing a naturally contaminated soil amended, in this case with Paulownia biochar (PB) and Bamboo biochar (BB) to fractionate Pb, Cd, Zn, and Cu using short sequential fractionation plans. The relationship of soil pH and organic matter and its effect on the redistribution of these metals were estimated. The results indicated that the acid-soluble metals decreased while the fraction bound to organic matter increased compared to untreated pots. The increase in the organic matter metal-bound was mostly at the expense of the decrease in the acid extractable and Fe/Mn bound ones. The highest application of PB increased the organically bound fraction of Pb, Cd, Zn, and Cu (62, 61, 34, and 61%, respectively), while the BB increased them (61, 49, 42, and 22%, respectively) over the control. Meanwhile, Fe/Mn oxides bound represents the large portion associated with zinc and copper. Concerning soil organic matter (SOM) and soil pH, as potential tools to reduce the risk of the target metals, a significant positive correlation was observed with acid-soluble extractable metal, while a negative correlation was obtained with organic matter-bound metal. The principal component analysis (PCA) shows that the total variance represents 89.7% for the TCPL-extractable and HMs forms and their relation to pH and SOM, which confirms the positive effect of the pH and SOM under PB and BB treatments on reducing the risk of the studied metals. The mobility and bioavailability of these metals and their geochemical forms widely varied according to pH, soil organic matter, biochar types, and application rates. As an environmentally friendly and economical material, biochar emphasizes its importance as a tool that makes the soil more suitable for safe cultivation in the short term and its long-term sustainability. This study proves that it reduces the mobility of HMs, their environmental risks and contributes to food safety. It also confirms that performing more controlled experiments, such as a pot, is a disciplined and effective way to assess the suitability of different types of biochar as soil modifications to restore HMs contaminated soil via controlling the mobilization of these minerals.


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