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  Lists best and worst alternatives