Reductive dechlorination and biodegradation of 2,4,6-trichlorophenol using sequential permeable reactive barriers:...

Area of Science:

• Environmental Science
• Environmental Chemistry
• Bioremediation

Background:

• 2,4,6-trichlorophenol (2,4,6-TCP) is a toxic organic compound often found in contaminated groundwater.
• Effective treatment methods are needed to remediate sites polluted with chlorophenols.

Purpose of the Study:

• To investigate the efficacy of a sequential barrier system for the reductive dechlorination and biodegradation of 2,4,6-TCP.
• To evaluate the combined performance of a chemical reactive barrier and a biological reactive barrier.

Main Methods:

• A laboratory-scale sequential barrier system was designed, comprising a palladium-coated iron (Pd/Fe) chemical barrier followed by an anaerobic microbial biobarrier.
• The system was tested for the degradation of 2,4,6-TCP and subsequent removal of intermediate products.

Main Results:

• Complete dechlorination of 2,4,6-TCP to phenol was achieved in the Pd/Fe chemical barrier, requiring a residence time of 30.2-21.2 hours.
• The biobarrier effectively removed approximately 100 microM of phenol within a residence time of 7-8 days.
• The sequential approach demonstrated enhanced overall treatability compared to individual barrier performances.

Conclusions:

• A sequential permeable reactive barrier system, integrating a chemical iron barrier and a biological barrier, is a promising technology for treating groundwater contaminated with chlorophenols.
• Preceding chemical dechlorination significantly improves the efficiency of subsequent biodegradation, enhancing overall contaminant remediation.