Biochar enhanced Floating Root Mats to Reduce Recalcitrant Contaminants of Emerging Concern from Wastewater Effluents

Floating Root Mats (FRM) have gained attention as nature-based wastewater treatment alternatives, and interest has grown in enhancing their design to effectively tackle contaminants of emerging concern (CEC). This bench-scale study assessed the performance of an innovative biochar-FRM configuration to improve the attenuation of ten recalcitrant CEC from wastewater. Three types of reactors were evaluated: (1) FRM with plants (Cyperus alternifolius) and biochar, (2) FRM with plants only, and (3) unplanted control reactors under two hydraulic loading rates (HLR) of 12 and 24 mm/day. The presence of plants in FRM increased up to 28% CEC removal, whilst the addition of biochar to planted FRM improved CEC removal by 41% compared to control. Untargeted analysis underscored similarly good performance of the developed biochar-FRM technology and microbiological analysis showed a link between CEC attenuation and increased abundance of key genera involved in biodegradation processes such as Exiguobacterium, Nocardia, Alysiosphaera, Rodobacter and Amaricoccus.