Sequential soil washing with mixed biosurfactants is suitable for simultaneous removal of multi-metals from soils with different properties, pollution levels and ages

Kumpienė

Carabante

et al. 2021

IJERPH

Self Cite

This paper presents experimental results from the use of biosurfactants in the remediation of a soil from a smelter in Poland. In the soil, concentrations of Cu (1659.1 mg/kg) and Pb (290.8 mg/kg) exceeded the limit values. Triple batch washing was tested as a soil treatment. Three main variants were used, each starting with a different plant-derived (saponin, S; tannic acid, T) or microbial (rhamnolipids, R) biosurfactant solution in the first washing, followed by 9 different sequences using combinations of the tested biosurfactants (27 in total). The efficiency of the washing was determined based on the concentration of metal removed after each washing (CR), the cumulative removal efficiency (Ecumulative) and metal stability (calculated as the reduced partition index, Ir, based on the metal fractions from BCR sequential extraction). The type of biosurfactant sequence influenced the CR values. The variants that began with S and R had the highest average Ecumulative for Cu and Pb, respectively. The Ecumulative value correlated very strongly (r > 0.8) with the stability of the residual metals in the soil. The average Ecumulative and stability of Cu were the highest, 87.4% and 0.40, respectively, with the S-S-S, S-S-T, S-S-R and S-R-T sequences. Lead removal and stability were the highest, 64–73% and 0.36–0.41, respectively, with the R-R-R, R-R-S, R-S-R and R-S-S sequences. Although the loss of biosurfactants was below 10% after each washing, sequential washing with biosurfactants enriched the soil with external organic carbon by an average of 27-fold (S-first variant), 24-fold (R first) or 19-fold (T first). With regard to environmental limit values, metal stability and organic carbon resources, sequential washing with different biosurfactants is a beneficial strategy for the remediation of smelter-contaminated soil with given properties.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Effect Of Sequential Soil Washing With Biosurfactants On Metal Removal From Smelter Contaminated Soilmentioning

confidence: 99%

See 1 more Smart Citation

Remediation of Smelter Contaminated Soil by Sequential Washing Using Biosurfactants

Kumpienė

Carabante

et al. 2021

IJERPH

Self Cite

“…Studies evaluating the metal stability (based on IR) in soils after washing were conducted by Gusiatin et al 54 . The authors have found that application of different biosurfactants as WAs (saponin, tannic acid, rhamnolipids) significantly increased the stability of Cd, Cu, Ni, Pb and Zn (based on the IR) in spiked soil.…”

Section: Suitability Of Different Environmental Indices For Assessmenmentioning

confidence: 99%

Suitability of environmental indices in assessment of soil remediation with conventional and next generation washing agents

Klik

Kulikowska

2020

Sci Rep

Remediation of soils contaminated with metal must ensure high efficiency of metals removal, reduce bioavailability of residual metals and decrease ecological risk. Thus, for comprehensive environmental soil quality assessment, different indices must be used. In this study, suitability of 8 indices was used for soil highly contaminated with Cu (7874.5 mg kg−1), moderately with Pb (1414.3 mg kg−1) and low with Zn (566.1 mg kg−1), washed in batch and dynamic conditions with both conventional and next-generation washing agents. The following indices were used: modified contamination factor (mCf), modified contamination factor degree (mCdeg), mobility factor (MF), reduced partition index (IR), potential ecological risk factor (Er,Z), modified potential ecological risk factor (Er,m), potential ecological risk index (RIZ) and modified ecological risk index (RIm). For mCf,mCdeg and IR own classification scale was proposed. It was proven that most useful indices for assessment of soil pollution with metals were mCf and mCdeg. The mCf together with the IR allow to simultaneous assessment of soil pollution and stability for individual metals. These indices were appropriate for soil contaminated with different concentrations of metals, washed under both hydrodynamic conditions using various washing agents and different effectiveness of metals removal. Thus, they may be considered as most useful for evaluation of remediation method, feasibility of washing agent and assessing soil quality after washing.

“…When Fe (II) is complexed to TA, it is unable to participate in Fenton-like processes and to mediate the formation of hydroxyl radicals [ 24 ]. There is little information on the use of TA in soil remediation and, moreover, only concerning soil washing [ 21 , 25 , 26 ] and phytoremediation [ 27 ], not soil flushing.…”

Section: Introductionmentioning

confidence: 99%

Short-Term Soil Flushing with Tannic Acid and Its Effect on Metal Mobilization and Selected Properties of Calcareous Soil

Kaal²,

Wasilewska

et al. 2021

IJERPH

Self Cite

Cadmium, Cu, Ni, Pb, and Zn removal via soil flushing with tannic acid (TA) as a plant biosurfactant was studied. The soil was treated for 30 h in a column reactor at a constant TA concentration and pH (3%, pH 4) and at variable TA flow rates (0.5 mL/min or 1 mL/min). In the soil leachates, pH, electrical conductivity (EC), total dissolved organic carbon, and metal concentrations were monitored. Before and after flushing, soil pH, EC, organic matter content, and cation exchange capacity (CEC) were determined. To analyze the organic matter composition, pyrolysis as well as thermally assisted hydrolysis and methylation coupled with gas chromatography-mass spectrometry were used. Metal fractionation in unflushed and flushed soil was analyzed using a modified sequential extraction method. The data on cumulative metal removal were analyzed using OriginPro 8.0 software (OriginLab Corporation, Northampton, MA, USA) and were fitted to 4-parameter logistic sigmoidal model. It was found that flushing time had a stronger influence on metal removal than flow rate. The overall efficiency of metal removal (expressed as the ratio between flushed metal concentration and total metal concentration in soil) at the higher flow rate decreased in this order: Cd (86%) > Ni (44%) > Cu (29%) ≈ Zn (26%) > Pb (15%). Metals were removed from the exchangeable fraction and redistributed into the reducible fraction. After flushing, the soil had a lower pH, EC, and CEC; a higher organic matter content; the composition of the organic matter had changed (incorporation of TA structures). Our results prove that soil flushing with TA is a promising approach to decrease metal concentration in soil and to facilitate carbon sequestration in soil.