Per- and polyfluoroalkyl substances (PFASs) are widespread and persistent in aquatic environments, their toxicity and bioaccumulation are the great concern among the scientific community and the public. Wastewater is regarded as a significant sink for PFASs. However, the effluents of wastewater treatment plants (WWTPs) can still cause aquatic problems due to the low removal efficiency of PFASs in the WWTPs. As an efficient and eco-friendly wastewater treatment and environmental cleanup technology, constructed wetland (CW) has been popularly used worldwide for treating various wastewaters. Several studies have investigated wetlands (natural or/and treatment wetlands) to remove PFASs from aqueous environments. The conventional CW system works on the principles of plant uptake, bioaccumulation, and substrate sorption to remove PFASs. The newly developed CW-microbial fuel technology (CW-MFC), as an intensified CW system, can simultaneously achieve enhanced wastewater treatment and bioenergy recovery and could open an integrated while eco-friendly way for PFASs removal. However, so far, no study has investigated the PFASs removal and their effects on the performance of the CW-MFC system. Therefore, the objective of this study was to explore the removal performance of PFASs by CW-MFC system under the coexistence of conventional contaminants in wastewater. Two CW-MFC systems were designed in closed- and/or open-circuit operating modes, respectively. Firstly, the removal performance of PFASs under different configurations was investigated and compared. The effects of PFASs on conventional contaminants' removal and bioelectrochemical performance of CW-MFC systems were then explored. When the concentrations of PFOA and PFOS in the influent were 6.46±0.52 and 9.34±0.87 μg/L, respectively, both closed-circuit and open-circuit operation of the CW-MFC systems demonstrated over 96% removal performance of PFAS. These results indicate that the CW-MFC system can effectively remove PFASs from wastewater, regardless of whether it is operated in an open or closed circuit. Moreover, the results showed that the removals of COD and TP in CW-MFC systems were less affected by PFASs under the influent COD and TP concentrations of 400 and 2.5 mg/L, respectively. However, with the efficient removal of PFASs, organic matter, and TP, some adverse effects on system performance were observed. For example, the
\rmNH_4^+\text-N 
and TN removal rates were decreased by approximately 7.22% and 2.45%, in the closed-circuit system, while those were sharply dropped by 13.51% and 13.98%, in the open-circuit system, respectively. Specifically, the average output voltage of the closed-circuit CW-MFC system decreased by 7.32% under the stress of PFASs. Anyhow, the outlook of CW-MFC treatment of PFASs shows promising from the aspects of the economy and potential degradation mechanism. Our study highlights that the CW-MFC system owns the potential to remove PFASs from the aqueous phase in an eco-friendly and cost-effective approach and provides important insights into the effects of the conventional contaminants’ removal and bioenergy variations before and during the PFASs co-existence. Overall, this study provides useful information for PFASs remediation in the aquatic environment for further study.
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