A tailored permeable reactive bio-barrier forin situgroundwater remediation: removal of 3-chlorophenol as a case study

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 ofPseudomonas putidamacro-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.

Automated summary

The present study investigates the bacterial aerobic biodegradation of reduced carbon-contaminants (RCC) in a pilot system using a tailored permeable reactive biobarrier (PRBB) with macro-capsules incorporating a built-in nutrient core to support bacterial growth. The findings demonstrate the efficient degradation of the RCC model compound and the environmental advantage of controlling excess nutrient release.