RemediationTechniques

RemediationTechniques - Remediation of Hazardous Waste...

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Remediation of Hazardous Waste Sites
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Light Nonaqueous Phase Liquids (LNAPL): gasoline, benzene, other solvents HOW CLEAN IS ‘CLEAN’? Dense Nonaqueous Phase Liquids (DNAPL): coal tar, transformer oil, PCBs, PAHs
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PHYSICAL TREATMENT TECHNOLOGIES 1. Free product recovery 1. Pump-and-treat 3. Soil vapor extraction 4. Multiphase extraction 5. Air sparging 6. Groundwater circulation wells 7. Induced fracturing 8. Soil heating Take advantage of physiochemical properties of the contaminant (e.g., density, solubility, viscosity, volatility) and affected media (e.g., solid/liquid/gas, bulk density, moisture content, permeability, porosity, particle size distribution) to remediate soil and groundwater
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Most widely used remediation technology Used as ‘stand-alone’ treatment and in conjunction with other treatment technologies Focuses on the extraction of contaminated groundwater to the surface for subsequent treatment Conventional P&T used in ~75% of Superfund sites where groundwater was contaminated Treated groundwater may be re-injected into subsurface or discharged PUMP-AND-TREAT EPA document posted
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SOIL VAPOR EXTRACTION  (SVE) EPA document posted A pressure gradient is  induced in the  unsaturated (vadose)  zone and air serves as  the medium for removal  of volatile contaminants  From Bandari et al., 2007 Also known as in situ  soil  ventin g or in situ  volatilization A vacuum extraction technology that can remove a variety of volatile and semi-volatile organic contaminants that are sorbed to soils Analogous to Pump-and- Treat because it removes organic contaminants into a moving fluid phase, but from soil and  unsaturated zone of  subsurface . . not from 
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Advantages Limitations Proven technology Air emission permits may be required Minimal site disturbance On site containment or treatment of extracted vapors needed Relatively short treatment times Not very effective in clayey or low permeability soils Efficient and cost-effective >90% contaminant removal may be achieved Can be combined with other technologies Lack of guidelines for optimal design, installation, and operation Pros and cons of Soil Vapor Extraction?
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Multi-Phase Extraction (MPE) EPA document posted Most widely used extension of SVE Can achieve simultaneous extraction of vapor-phase, dissolved-phase, and non- aqueous-phase contamination in one borehole High vacuum is applied to a drop/slurp tube and soil vapor enters from vadose zone; this entrains groundwater and organic contaminants at tip of drop/slurp tube Most effective in formations with moderate permeabilities; highly permeable formations
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Advantages Limitations Effective at increasing water and vapor extraction
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This note was uploaded on 12/08/2010 for the course CE 2400 taught by Professor Colberg during the Spring '10 term at Wyoming.

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RemediationTechniques - Remediation of Hazardous Waste...

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