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Characterization of Lead Removal from Contaminated Soils by Nontoxic Soil‐Washing Agents
Author(s) -
Neilson Julia W.,
Artiola Janick F.,
Maier Raina M.
Publication year - 2003
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2003.8990
Subject(s) - soil water , rhamnolipid , chemistry , environmental chemistry , soil contamination , human decontamination , environmental remediation , contamination , environmental science , soil science , waste management , geology , biology , bacteria , engineering , pseudomonas aeruginosa , paleontology , ecology
Few effective strategies exist for remediating and restoring metal‐contaminated soils. We have evaluated the potential of two environmentally compatible, nondestructive, biological soil‐washing agents for remediating aged, lead‐contaminated soils. Two contaminated soils were washed with 10 m M rhamnolipid biosurfactant and 5.3% carboxymethyl‐β‐cyclodextrin (CMCD). The metal removal efficiency of these agents was compared with 10 m M diethylenetriamine pentaacetic acid (DTPA) and 10 m M KNO 3 Lead removal rates by both soil‐washing agents exceeded the removal by KNO 3 , but were an order of magnitude less than removal by the synthetic chelator, DTPA. Analysis of soil extractions revealed that the Pb in the first soil (3780 mg kg −1 ) was primarily associated with the soluble, exchangeable, oxide, and residual fractions while the Pb in the second soil (23 900 mg kg −1 ) was found in the soluble, exchangeable, carbonate, and residual fractions. After 10 consecutive washes, rhamnolipid had removed 14.2 and 15.3% of the Pb from the first and second soils, respectively, and CMCD had removed 5 and 13.4% from the same two soils. The Pb removal rate by both agents either increased or was consistent throughout the 10 extractions, indicating a potential for continued removal with extended washing. Significant levels of Cu and Zn in both soils did not prevent Pb removal by either agent. Interestingly, the effectiveness of each agent varied as a function of Pb speciation in the soil. Rhamnolipid was more effective than CMCD in removing Pb bound to amorphous iron oxides, while both agents demonstrated similar potential for removing soluble, exchangeable, and carbonate‐bound Pb. Neither agent demonstrated potential for the complete remediation of metal‐contaminated soils.