Co-Removal of Perfluorooctanoic Acid and Nitrate from Water by Coupling Pd Catalysis with Enzymatic Biotransformation

Min Long; Chen-Wei Zheng; Manuel A Roldan; Chen Zhou; Bruce E Rittmann

doi:10.1021/acs.est.3c10377

Co-Removal of Perfluorooctanoic Acid and Nitrate from Water by Coupling Pd Catalysis with Enzymatic Biotransformation

Environ Sci Technol. 2024 May 17. doi: 10.1021/acs.est.3c10377. Online ahead of print.

Authors

Min Long^{1

2}, Chen-Wei Zheng², Manuel A Roldan³, Chen Zhou^{2

4

5}, Bruce E Rittmann²

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
² Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85281, United States.
³ Eyring Materials Center, Arizona State University, Tempe, Arizona 85281, United States.
⁴ Institute for the Environment and Health, Nanjing University, Suzhou Campus, Suzhou 215163, China.
⁵ State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.

PMID: 38757358
DOI: 10.1021/acs.est.3c10377

Abstract

PFAS (poly- and per-fluorinated alkyl substances) represent a large family of recalcitrant organic compounds that are widely used and pose serious threats to human and ecosystem health. Here, palladium (Pd⁰)-catalyzed defluorination and microbiological mineralization were combined in a denitrifying H₂-based membrane biofilm reactor to remove co-occurring perfluorooctanoic acid (PFOA) and nitrate. The combined process, i.e., Pd-biofilm, enabled continuous removal of ∼4 mmol/L nitrate and ∼1 mg/L PFOA, with 81% defluorination of PFOA. Metagenome analysis identified bacteria likely responsible for biodegradation of partially defluorinated PFOA: Dechloromonas sp. CZR5, Kaistella koreensis, Ochrobacterum anthropic, and Azospira sp. I13. High-performance liquid chromatography-quadrupole time-of-flight mass spectrometry and metagenome analyses revealed that the presence of nitrate promoted microbiological oxidation of partially defluorinated PFOA. Taken together, the results point to PFOA-oxidation pathways that began with PFOA adsorption to Pd⁰, which enabled catalytic generation of partially or fully defluorinated fatty acids and stepwise oxidation and defluorination by the bacteria. This study documents how combining catalysis and microbiological transformation enables the simultaneous removal of PFOA and nitrate.

Keywords: H2-based membrane biofilm reactor (MBfR); PFOA mineralization; Pd catalysis; nitrate.