Iron (hydr)oxide minerals-microbe interaction associated retention capacity boost and reaction rate fluctuation for perfluorooctanoic acid in an in-situ iron-based and microbe-based sustained-release system

Based on the inefficient elimination of emerging contaminant perfluorooctanoic acid (PFOA) and the unpredictable performance of the filed-scale system, a novel in-situ iron-based and microbe-based sustained-release system and filed-scale model were developed to address the above issues in this study. Especially, the PFOA-microbe-mineral interaction in various types of groundwater and the relevant mechanism were quantitatively and deeply studied. The results showed that the sustained-release interaction system in HCO3− type groundwater exhibited a greater retardation effect (Kd = 0.73 cm3 g−1) on PFOA compared to the interaction system under no ions condition (Kd = 0.49 cm3 g−1) or microbe system (Kd = 0.43 cm3 g−1). Moreover, the reaction rate λ of PFOA exhibited minimal fluctuation in HCO3− type groundwater, indicating lower competition from HCO3− ions for occupancy site and resulting in less PFOA repulsed to the lower reactive region (with lower Fe2+ and microorganism cells concentrations). Furthermore, the retardation effect for PFOA was boosted by secondary minerals-microbe interaction and joint adsorption. HCO3− facilitated the minerals-microbes interaction, leading to increased formation of β-FeOOH and improved retardation effect for PFOA. Additionally, the functional microorganisms Pseudomonas and Delftia were combined to drive the Fe3+/Fe2+ cycle and PFOA biochemical transformation. The two-dimensional spatiotemporal evolution simulation results showed that pollutant flux (transport risk) of PFOA in HCO3− type groundwater system (0.124 × 10−3 mg·(m2·s)−1) can be reduced by 23.0% compared to that in NO3− type groundwater system (0.161 × 10−3 mg·(m2·s)−1). This study quantitatively revealed the coupling effect of minerals, microbes, and ions on PFOA, contributing to optimizing the sustained-release system for effectively remediating different types of PFOA-contaminated groundwater. [Display omitted] •Coupling effect of minerals-microbe-ions was quantitatively revealed by the multi-process model.•From laboratory studies to field-scale system application simulation predictions were designed.•Retention capacity boost induced by secondary minerals-microbe interaction and joint adsorption.•Iron (hydr)oxide minerals-microbe interacted with HCO3− exhibited a superior retardation for PFOA.•PFOA reaction rate fluctuation in interaction system was least in the HCO3−-occurrence environment.