A tailored permeable reactive bio-barrier for in situ groundwater remediation: removal of 3-chlorophenol as a case study

ABSTRACT

The present study explored bacterial aerobic biodegradation of reduced carbon-contaminants (RCC) in a pilot system mimicking remediation of a saturated aquifer in a permeable reactive biobarrier (PRBB). Bioaugmentation was performed with a pure culture of Pseudomonas putida macro-encapsulated in a cellulose-acetate porous envelope and integrated transversely to the flow trajectory of the fluid in the biobarrier and compared with controls without capsules. The macro-encapsulation technique applied allowed the incorporation of a built-in nutrient core for the slow release of macronutrients, i.e. N, P, instead of exogenous nutrients supply. 3-Chlorophenol (3CP) at a concentration range of 350–500 mg/L was chosen as an RCC model compound. The findings indicate efficient 3CP biodegradation during the PRBB operation with a similar degree of transformation (76 ± 2% and 72 ± 2%) and mineralization (55 ± 4% vs. 49 ± 3%) for exogenous and built-in nutrients supply, respectively. The extent of dechlorination in both cases (54 ± 10% vs. 40 ± 2%, respectively) followed mineralization rather than transformation, suggesting that Cl⁻ release took place in late transformation stages. Negligible decontamination was observed in the control system without bioaugmentation. Concluding, tailored PRBB with macro-capsules incorporating a built-in nutrient core to support bacterial growth presents a significant environmental advantage controlling excess nutrients release required in bioremediation of oligotrophic systems.

GRAPHICAL ABSTRACT

KEYWORDS:

• Permeable reactive biobarrriers
• macro-encapsulation
• exogenous nutrients contamination
• groundwater remediation
• bioaugmentation

Acknowledgements

This research was partially supported by the Chief Scientist Office of the Ministry of Environmental Protection of Israel under grant number 111-11-4.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was partially supported by the Chief Scientist Office of the Ministry of Environmental Protection of Israel under [grant number 111-11-4].