Assessment of intensified constructed wetlands for the attenuation of PMT compounds from groundwater and wastewater: Characterization of biofilm communities

The occurrence of Persistent, Mobile, and Toxic (PMT) substances in water bodies has become a major social and environmental concern. This study assesses the effectiveness of using bioelectrochemically-assisted constructed wetlands (CWs) based on electroconductive coke in two granulometric sizes (0.5-2 and 2-5 mm) for removing PMT compounds, including short and ultra-short chain PFAS (PFBS, 4C; PFPeA, 4C; and TFMS, 1C), benzotriazoles (1H-benzotriazole, BTR; 5-methyl-1H-benzotriazole, MBTR) and carbamazepine (CBZ) from groundwater and secondary-treated wastewater. Our results revealed that the presence of vegetation, the type of water, the filling material, and the coke granulometric-size determined the removal efficiency of PMT compounds. Planted systems on the largest granulometric-size of coke achieved the greatest removals for the targeted compounds (84 %, average) in wastewater. Untargeted analysis confirmed that such combination also achieved the highest reduction of water chemical complexity, decreasing >50 % of the peak areas of over 90 % of the features from wastewater. Microbiome analysis (16S) of that substrate biofilm showed the presence of Mycobacterium and Rhizobium genera, indicating the importance of both, water matrix and the filling material in the reduction of PMT compounds. In summary, combining electroconductive coke with vegetation is a promising strategy for removing PMT compounds from water bodies. • Plants were key to the removal of PMT substances by fostering biodegradation. • PMT substances were reduced more effectively in wastewater compared to groundwater. • High-granulometry coke systems obtained the best PMT substance removal (84 %). • Intensified CWs reduced over a 50 % the peak intensity for 90 % of water features. • Mycobacterium and Rhizobium genera may favour the removal of PMT-compounds.