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Section Three SITE REMEDIATION B. SOIL REMEDIATION 15 EVALUATION OF IN SITU SOIL FLUSHING TECHNIQUES FOR HEAVY METALS REMOVAL FROM CONTAMINATED SOILS J. C. O'Shaughnessy, Professor Professor R. A. D'Andrea, Associate Professor M. R. Canniff, T. J. St Germain, S. Venkataramanappa, and M. J. Macaulay, Graduate Research Assistants Department of Civil Engineering Worcester Polytechnic Institute, Worcester, Massachusetts 01609 BACKGROUND INFORMATION The constant use of hazardous and toxic materials has created numerous examples of severe environmental degradation. A result of past and present waste disposal practices, shipping of trade chemicals, and other intentional misuses of hazardous substances have resulted in the release of these materials into the environment. The end result is the required remediation of more and more existing hazardous waste sites. With the enforcement of Land Disposal Restrictions (LDRs) at Superfund sites, treatment of heavy metal-contaminated soils is required before disposing of the soils at a disposal facility. In situ soil flushing has been found to be effective at extracting heavy metals from contaminated soils in laboratory tests and has been selected, through the Record of Decision (ROD), as a remedial alternative to clean the Lipari Landfill located in New Jersey. As shown in Table I, the most widespread class of soil contaminant at Superfund sites was found to be slightly water soluble organics which included aromatics and halogenated hydrocarbons. Based on research data available on treatment of soils contaminated with slightly water soluble organics, the most promising countermeasure is a full scale in situ countermeasure operation with water injection and recovery. Surfactants and/or other chemical countermeasures may be added to increase the remediation effort.1 If in situ flushing is used, then the implication of this remediation method on heavy metals must also be understood. The solubility of heavy metals in soil largely determines their mobility in the environment and, therefore, the degree of pollution and environmental damage. The solubility depends on soil/solution pH, soil texture and composition, the amount and type of organic compounds in the soil, soil moisture content and temperature, and the type and number of other ions present in the soil.2"5 The major metal removal processes in soil are adsorption, precipitation, biological assimilation and chelation, although the metal will stay in solution when chelated with a sequestering agent. Clean, coarse grained soils containing reduced organic matter provide relatively little adsorption surface and, therefore, are more inclined to let soluble metals pass through with groundwater flow. Silt and clay sized soil particles and organic soils build up metal concentration by removing metal from solution and, thus, decrease metal leaching through to groundwater. The number and type of adsorption sites on a given soil is determined by the soil type and composition. All ions in solution will compete for these sites and also compete for available ligands for chelation/complexing. Organic ligands, such as fluvic and humic acid, can impact metals mobility. Precipitation of metals depends on the soil composition which then can provide the necessary carbonates, hydrous oxides, oxides, phosphates and sulfides that are required to form precipitates. 48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 123
Object Description
Purdue Identification Number | ETRIWC199315 |
Title | Evaluation of in situ soil flushing techniques for heavy metals removal from contaminated soils |
Author |
O'Shaughnessy, James C. D'Andrea, R. A. Canniff, M. R. St-Germain, T. J. Venkataramanappa, S. Macaulay, M. J. |
Date of Original | 1993 |
Conference Title | Proceedings of the 48th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,21159 |
Extent of Original | p. 123-140 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-11-03 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 123 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | Section Three SITE REMEDIATION B. SOIL REMEDIATION 15 EVALUATION OF IN SITU SOIL FLUSHING TECHNIQUES FOR HEAVY METALS REMOVAL FROM CONTAMINATED SOILS J. C. O'Shaughnessy, Professor Professor R. A. D'Andrea, Associate Professor M. R. Canniff, T. J. St Germain, S. Venkataramanappa, and M. J. Macaulay, Graduate Research Assistants Department of Civil Engineering Worcester Polytechnic Institute, Worcester, Massachusetts 01609 BACKGROUND INFORMATION The constant use of hazardous and toxic materials has created numerous examples of severe environmental degradation. A result of past and present waste disposal practices, shipping of trade chemicals, and other intentional misuses of hazardous substances have resulted in the release of these materials into the environment. The end result is the required remediation of more and more existing hazardous waste sites. With the enforcement of Land Disposal Restrictions (LDRs) at Superfund sites, treatment of heavy metal-contaminated soils is required before disposing of the soils at a disposal facility. In situ soil flushing has been found to be effective at extracting heavy metals from contaminated soils in laboratory tests and has been selected, through the Record of Decision (ROD), as a remedial alternative to clean the Lipari Landfill located in New Jersey. As shown in Table I, the most widespread class of soil contaminant at Superfund sites was found to be slightly water soluble organics which included aromatics and halogenated hydrocarbons. Based on research data available on treatment of soils contaminated with slightly water soluble organics, the most promising countermeasure is a full scale in situ countermeasure operation with water injection and recovery. Surfactants and/or other chemical countermeasures may be added to increase the remediation effort.1 If in situ flushing is used, then the implication of this remediation method on heavy metals must also be understood. The solubility of heavy metals in soil largely determines their mobility in the environment and, therefore, the degree of pollution and environmental damage. The solubility depends on soil/solution pH, soil texture and composition, the amount and type of organic compounds in the soil, soil moisture content and temperature, and the type and number of other ions present in the soil.2"5 The major metal removal processes in soil are adsorption, precipitation, biological assimilation and chelation, although the metal will stay in solution when chelated with a sequestering agent. Clean, coarse grained soils containing reduced organic matter provide relatively little adsorption surface and, therefore, are more inclined to let soluble metals pass through with groundwater flow. Silt and clay sized soil particles and organic soils build up metal concentration by removing metal from solution and, thus, decrease metal leaching through to groundwater. The number and type of adsorption sites on a given soil is determined by the soil type and composition. All ions in solution will compete for these sites and also compete for available ligands for chelation/complexing. Organic ligands, such as fluvic and humic acid, can impact metals mobility. Precipitation of metals depends on the soil composition which then can provide the necessary carbonates, hydrous oxides, oxides, phosphates and sulfides that are required to form precipitates. 48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 123 |
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Color Depth | 8 bit |
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