Chelant soil-washing technology for metal-contaminated soil

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This article was downloaded by: [University of Windsor]On: 30 September 2014, At: 10:07Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UKEnvironmental TechnologyPublication details, including instructions for authors and subscription information: soil-washing technology for metal-contaminated soilDavid Voglara & Domen Lestanaba Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101,Ljubljana 1000, Sloveniab Envit Ltd., Vojkova 63, Ljubljana 1000, SloveniaPublished online: 06 Jan 2014.To cite this article: David Voglar & Domen Lestan (2014) Chelant soil-washing technology for metal-contaminated soil,Environmental Technology, 35:11, 1389-1400, DOI: 10.1080/09593330.2013.869265To link to this article: SCROLL DOWN FOR ARTICLETaylor & Francis makes every effort to ensure the accuracy of all the information (the Content) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of theContent. Any opinions and views expressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon andshould be independently verified with primary sources of information. Taylor and Francis shall not be liable forany losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoeveror howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use ofthe Content.This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at Technology, 2014Vol. 35, No. 11, 13891400, soil-washing technology for metal-contaminated soilDavid Voglara and Domen Lestana,baAgronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, Ljubljana 1000, Slovenia;bEnvit Ltd., Vojkova 63, Ljubljana 1000, Slovenia(Received 29 July 2013; accepted 18 November 2013 )We demonstrate here, in a pilot-scale experiment, the feasibility of ethylenediaminetetraacetate (EDTA)based washingtechnology for soils contaminated with potentially toxic metals. Acid precipitation coupled to initial alkaline toxic metalremoval and an electrochemical advanced oxidation process were used for average recovery of 76 2% of EDTA per batchand 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 soilextraction, screen for soil/gravel separation, filter chamber presses for soil/liquid and recycled EDTA separation and soilrinsing, 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 32.6mg kg1of Pb, Zn and Cd, respectively, in nine 60 kg soil batches. Concentrations of Pb and Zn remaining in the remediated soiland bioaccessible from the simulated human intestinal phase soil were reduced by 97% and 96% and were brought underthe level of determination for Cd. In the most cost-effective operation mode, the material and energy costs of remediationamounted to 50.5 ton1 soil and the total cost to 299 ton1.Keywords: toxic metals; EDTA; soil washing; pilot scale; cost analysis1. IntroductionPotentially toxic metals (PTMs), commonly referred toas heavy metals, are ubiquitous soil contaminants.[1,2]There are more than 1.8 million contaminated sites in west-ern central and south-eastern Europe, of which 240,000 arein need of remedial treatment. In almost 40% of these sites,PTMs are the most important contaminants.[3] In the USA,PTMs are present in 77% of the Superfund Sites (NationalPriority List), in 72% of the Department of Defense Sitesand in 55% of the Department of Energy Sites.[4]The proper remediation and management of PTM-contaminated soil is a generally widespread and costlyissue. The selection of appropriate remediation technol-ogy depends on the contamination and soil type and finaluse of the reclaimed land. In this pilot-scale experiment,we used the chelating agent ethylenediaminetetraacetate(EDTA) for ex situ extraction of Pb, Zn and Cd fromcontaminated garden soil. Soil washing with an aqueoussolution of EDTA is considered to be a remedial optionwitha potentially low impact on soil quality.[5] Divalent andtrivalent PTMs can be EDTA-extracted from soil becausethe reported ordering of EDTA complex stability con-stants Na+ < Mg2+ < Ca2+ < Fe2+ < Al3+ < Zn2+


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