Control of trichloroethylene plume migration using a biobarrier system: a field-scale study

Area of Science:

• Environmental Engineering
• Geochemistry
• Microbiology

Background:

• Trichloroethylene (TCE) is a widespread groundwater contaminant.
• Controlling TCE plume migration is crucial for environmental protection.
• Biobarriers offer a promising in-situ remediation approach.

Purpose of the Study:

• To evaluate the effectiveness of polycolloid substrate (PS) biobarriers for controlling TCE plume migration.
• To assess the impact of PS injection on groundwater chemistry and microbial activity.
• To determine the potential for enhanced reductive dechlorination of TCE.

Main Methods:

• Installation of a field-scale biobarrier using PS injection wells at 5-m intervals.
• Injection of approximately 15 L of PS per well, containing soybean oil, lactate, and surfactants.
• Monitoring of TCE, total organic carbon (TOC), dissolved oxygen (DO), and oxidation-reduction potential (ORP) over 100 days.

Main Results:

• TCE concentrations decreased from 87 μg/L to below 1 μg/L within 35 days.
• TOC levels increased significantly, indicating substrate release and microbial activity.
• DO and ORP dropped to anaerobic conditions (DO < 0.1 mg/L, ORP < -14 mv) within 20 days.
• TCE degradation by-products were detected, confirming reductive dechlorination.

Conclusions:

• Polycolloid substrate biobarriers are effective in controlling TCE plume migration.
• PS injection successfully created and maintained anaerobic conditions conducive to reductive dechlorination.
• The study confirms PS as a viable strategy for enhancing TCE biodegradation in groundwater.