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Merck

Chelant soil-washing technology for metal-contaminated soil.

Environmental technology (2014-04-08)
David Voglar, Domen Lestan
ABSTRACT

We demonstrate here, in a pilot-scale experiment, the feasibility of ethylenediaminetetraacetate (EDTA)based washing technology for soils contaminated with potentially toxic metals. Acid precipitation coupled to initial alkaline toxic metal removal and an electrochemical advanced oxidation process were used for average recovery of 76 +/- 2% of EDTA per batch and total recycle of water in a closed process loop. No waste water was generated; solid wastes were efficiently bitumen-stabilized before disposal. The technology embodiment, using conventional process equipment, such as a mixer for soil extraction, screen for soil/gravel separation, filter chamber presses for soil/liquid and recycled EDTA separation and soil rinsing, continuous centrifuge separator for removal of precipitated metals and electrolytic cells for process water cleansing, removed up to 72%, 25% and 66% of Pb, Zn and Cd from garden soil contaminated with up to 6960, 3797 and 32.6 mg kg(-1) of Pb, Zn and Cd, respectively, in nine 60kg soil batches. Concentrations of Pb and Zn remaining in the remediated soil and bioaccessible from the simulated human intestinal phase soil were reduced by 97% and 96% and were brought under the level of determination for Cd. In the most cost-effective operation mode, the material and energy costs of remediation amounted to 50.5 Euros ton(-1) soil and the total cost to 299 Euros ton(-1).

MATERIALS
Product Number
Brand
Product Description

Supelco
Ethylenediaminetetraacetic acid disodium salt dihydrate, Pharmaceutical Secondary Standard; Certified Reference Material
USP
Edetate disodium, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Ethylenediaminetetraacetic acid calcium disodium salt hydrate
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, reagent grade, 98.5-101.5% (titration)
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, suitable for electrophoresis, for molecular biology, 99.0-101.0% (titration)
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, 98.5-101.5%, BioUltra
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, Sigma Grade, suitable for plant cell culture, 98.5-101.5%
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, ≥97.0% (KT)
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, BioUltra, for molecular biology, ≥99.0% (T)
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, meets analytical specification of Ph. Eur., BP, USP, FCC, 99.0-101.0%
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, ACS reagent, 99.0-101.0%
Disodium edetate, European Pharmacopoeia (EP) Reference Standard
Sodium calcium edetate, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Ethylenediaminetetraacetic acid, 99.995% trace metals basis
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt solution, BioUltra, for molecular biology, pH 8.0, ~0.5 M in H2O
Sigma-Aldrich
Ethylenediaminetetraacetic acid, BioUltra, ≥99.0% (KT)
Sigma-Aldrich
Ethylenediaminetetraacetic acid, ≥98.0% (KT)
Sigma-Aldrich
Ethylenediaminetetraacetic acid solution, 0.02% in DPBS (0.5 mM), sterile-filtered, BioReagent, suitable for cell culture
Sigma-Aldrich
Ethylenediaminetetraacetic acid, ACS reagent, 99.4-100.6%, powder
Sigma-Aldrich
Ethylenediaminetetraacetic acid, anhydrous, crystalline, BioReagent, suitable for cell culture
Sigma-Aldrich
Ethylenediaminetetraacetic acid, purified grade, ≥98.5%, powder
Sigma-Aldrich
Ethylenediaminetetraacetic acid, anhydrous, BioUltra, ≥99% (titration)
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt solution, for molecular biology, 0.5 M in H2O, DNase, RNase, NICKase and protease, none detected
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt solution, 2%, solution