Development, operation, and long-term performance of a full-scale biocurtain utilizing bioaugmentation

Area of Science:

• Environmental Microbiology
• Bioremediation
• Groundwater Remediation

Background:

• Carbon tetrachloride (CT) and nitrate contamination pose significant environmental risks.
• Bioaugmentation offers a promising strategy for in-situ contaminant degradation.

Purpose of the Study:

• To evaluate the large-scale field performance of bioaugmentation for CT and nitrate removal.
• To assess the effectiveness of a bioaugmentation strategy using Pseudomonas stutzeri KC.

Main Methods:

• A field-scale bioaugmentation was conducted using Pseudomonas stutzeri KC in a CT- and nitrate-impacted aquifer.
• A biocurtain was established using closely spaced injection/extraction wells with intermittent addition of acetate, alkali, and phosphorus.
• Groundwater flow was manipulated to enhance contact with the biocurtain.

Main Results:

• High CT removal efficiencies (98-99.9%) were achieved and sustained for over 4 years.
• Effective colonization of the aquifer by strain KC was observed (>10(5) cells/g).
• Nitrate removal efficiencies varied from 60% to nearly 100% depending on acetate concentration.

Conclusions:

• Closely spaced wells and intermittent substrate addition are effective for subsurface bioaugmentation.
• The bioaugmentation strategy achieved uniform contaminant removal across a significant vertical depth.
• This study demonstrates a successful and sustainable approach to groundwater remediation.