Superb green cycling strategies for microbe-Fe0 neural network-type interaction: Harnessing eight key genes encoding enzymes and mineral transformations to efficiently treat PFOA

To address time-consuming and efficiency-limited challenges in conventional zero-valent iron (ZVI, Fe0) reduction or biotransformation for perfluorooctanoic acid (PFOA) treatment, two calcium alginate-embedded amendments (biochar-immobilized PFOA-degrading bacteria (CB) and ZVI (CZ)) were developed to construct microbe-Fe0 high-rate interaction systems. Interaction mechanisms and key metabolic pathways were systematically explored using metagenomics and a multi-process coupling model for PFOA under microbe-Fe0 interaction. Compared to Fe0 (0.0076 day−1) or microbe (0.0172 day−1) systems, the PFOA removal rate (0.0426 day−1) increased by 1.5 to 4.6 folds in the batch microbe-Fe0 interaction system. Moreover, Pseudomonas accelerated the transformation of Fe0 into Fe3+, which profoundly impacted PFOA transport and fate. Model results demonstrated microbe-Fe0 interaction improved retardation effect for PFOA in columns, with decreased dispersivity a (0.48 to 0.20 cm), increased reaction rate λ (0.15 to 0.22 h−1), distribution coefficient Kd (0.22 to 0.46 cm3∙g−1), and fraction f´(52 % to 60 %) of first-order kinetic sorption of PFOA in microbe-Fe0 interaction column system. Moreover, intermediates analysis showed that microbe-Fe0 interaction diversified PFOA reaction pathways. Three key metabolic pathways (ko00362, ko00626, ko00361), eight functional genes, and corresponding enzymes for PFOA degradation were identified. These findings provide insights into microbe-Fe0 “neural network-type” interaction by unveiling biotransformation and mineral transformation mechanisms for efficient PFOA treatment. [Display omitted] •Superb green cycling strategies for microbe-Fe0 neural network-type interaction to rapidly treat PFOA.•The reaction rate of PFOA increased by 1.5 to 4.6 folds in the microbe-Fe0 interaction system.•Microbe-Fe0 interaction improved the retardation effect for PFOA in vertical reaction columns.•Three related key metabolic pathways (ko00362, ko00626, ko00361) for PFOA were identified.•Eight key functional genes and corresponding enzymes for PFOA degradation were revealed.