TCE Contamination Overview
Trichloroethylene or trichloroethene (TCE) is a synthetic chemical often historically used:
- as an anesthetic
- as a degreaser for metal parts
- to decaffinate coffee
- for dry-cleaning (eventually being phased out in favor of TCE).
Contamination by TCE in groundwater is frequent for developed commercial and industrial areas. Due to partitioning, soil contamination commonly makes up the bulk of TCE mass relative to groundwater.
Applicable Remediation Technologies for Trichloroethylene
Physical
Air Sparging: Excellent – As the vapor pressure is greater than 1 mm Hg, air sparging is an effective process for the remediation of TCE in groundwater.
SVE: Excellent – As the vapor pressure is greater than 1 mm Hg, soil vapor extraction is an effective process for the remediation of TCE in soil.
Thermal: Excellent – As TCE is already a volatile compound and will work with SVE at typical soil temperatures (see above), thermally enhanced SVE should be used when the TCE is in low permeability material or short remediation time frames are required.
Pump and Treat: Good to Poor – Pump and treat is usually not an effective source remedy for TCE in groundwater, when there is significant non-aqueous mass present (absorbed to soil or non-aqueous phase liquids). There is usually non-aqeous mass present when TCE is detected in groundwater.
Chemical
In Situ Chemical Oxidation (ISCO): Excellent – A variety of oxidant chemistries can successfully mineralize TCE in groundwater and soil.
In Situ Chemical Reduction (ISCR): Excellent – ISCR (for example, zero valent iron or ZVI) has been successful at remediating TCE in groundwater and soil.
Biological
Aerobic: Poor – Generally trichloroethylene can only be degraded aerobically via a cometabolic process, requiring the presence of petroleum compounds.
Anaerobic: Excellent – TCE can be anaerobically treated, though often enhancement through the use of a carbon substrate, nutrients, or pH adjusters may be needed to ensure complete transformation of TCE to innocuous end products.
Absorption
Activated Carbon: TCE can adsorb to activated carbon.
Properties:
Molecular weight (g/mole): 131.39
Solubility (mg/L): 1,280
Vapor pressure (mm Hg): 69
Henry’s Coefficient (unitless): 0.4026983
Organic Carbon Partitioning Coefficient (cm3/g): 60.7