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Chemical/physical Remediation Technologies. Kara Reed Kirstyn White. Thermal De-sorption. Physical separation process designed to volatilize water and organic contaminants Not designed to destroy organics Three types: Direct fired Indirect fired Indirect heated.
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Chemical/physical Remediation Technologies Kara Reed Kirstyn White
Thermal De-sorption • Physical separation process designed to volatilize water and organic contaminants • Not designed to destroy organics • Three types: • Direct fired • Indirect fired • Indirect heated
High or low-temp thermal de-sorption • Offgas is collected and either: • Incinerated in afterburner • Collected on activated charcoal • Recovered in condensation equipment
Benefits • Direct fired: • Kiln temp much lower than that of incinerator • Lighter for transport, less setup & maintenance • Indirect fired: • W/ offgas condensing system, no limitation on metals remediated • Drawbacks: • Specific particle size requirements • De-watering may be needed to reduce moisture • Highly abrasive contaminants damage processor unit
Soil Flushing • In-situ • Co-solvent solution • Breaks down contaminants • Dissolved contaminants leach into groundwater; Collected with extraction wells and treated • Useful for: heavy metals, halogenated solvents, aromatics, gasoline, fuels, PCBs
Benefits: • Transportable • Low cost • Closed system (unaffected by external conditions) • Drawbacks: • Leaves co-solvent residuals in soil • Not applicable to low-permeability soils
Composting • Ex-situ • Microorganisms break down explosives • Converts them into harmless by-products • Provide microorganisms with nutrients • Carbon, nitrogen, phosphorus, potassium • Some additives: manure & potato wastes
Benefits: • No harmful by-products • Costs less than excavation & incineration • Can sell humus-rich soil for $10/ton • Will enhance region if soil replaced • Drawbacks: • Process may take extended period of time • Must remove soil, potentially disturbing biota and wildlife • Must test for optimal mixture of contaminated soil and additives
Enhanced Bioremediation • In-situ • Stimulating microorganisms present in soil • Circulating water-based solutions through soil • Aerobic or anaerobic microroganisms
Benefits: • Soil can remain in place • No harmful by-products • Cost-effective • Drawbacks: • Slows at lower temperatures • May take years to degrade • Not applicable to highly heterogeneous subsurface environments (i.E. Clay)
Other Remediation Alternatives • www.frtr.gov/matrix2/section3/table3_2.html • Lists best and worst alternatives