Bioaugmentation for treating transient 4-fluorocinnamic acid shock loads in a rotating biological contactor

Area of Science:

• Environmental microbiology
• Bioremediation technologies
• Wastewater treatment

Background:

• Industrial wastewater often contains persistent organic pollutants like 4-fluorocinnamic acid (4-FCA).
• Rotating biological contactors (RBCs) are utilized for biological wastewater treatment.
• Effective degradation of fluorinated aromatic compounds presents a significant challenge.

Purpose of the Study:

• To evaluate the efficacy of a rotating biological contactor (RBC) in treating shock loadings of 4-fluorocinnamic acid (4-FCA).
• To assess the impact of bioaugmentation on the RBC's performance in degrading 4-FCA.
• To investigate the microbial community dynamics and intermediate metabolite formation during 4-FCA treatment.

Main Methods:

• Application of intermittent shock loadings of 4-FCA to an RBC system.
• Bioaugmentation of the RBC with a 4-FCA degrading bacterial strain.
• Analysis of bacterial community structure using denaturing gradient gel electrophoresis (DGGE).
• Isolation and characterization of bacterial strains capable of transforming and mineralizing 4-FCA.

Main Results:

• Initial treatment showed limited 4-FCA mineralization and accumulation of 4-fluorobenzoate (4-FBA).
• Bioaugmentation improved 4-FCA removal capacity but performance declined over time, with persistent 4-FBA accumulation.
• Distinct bacterial communities were observed across different stages of the RBC.
• Only a few isolated strains demonstrated complete mineralization of 4-FCA.

Conclusions:

• Bioaugmentation can enhance the removal of fluorinated compounds like 4-FCA.
• Intermittent feeding strategies may compromise the long-term efficiency of bioreactors.
• Further optimization of feeding regimes and microbial consortia is needed for robust bioremediation of such pollutants.