Trade-offs between organic micropollutants removal and microbiological risks: An evaluation of plant species in nature-based biofiltration systems
Yanghui Xiong, Hongbo Zhang, Hong Cheng, Paweł Marczewski, Yevhen Myshkevych, Pei-Ying Hong
Plant species with extensive root systems and high biomass in nature-based biofiltration systems can enhance the removal of conventional contaminants. The growing concern over organic micropollutants (OMPs) necessitates a reevaluation of these selection criteria for reclaimed water treatment, alongside consideration of microbiological safety. In this study, four local ornamental plants were evaluated in submerged biofiltration systems for their performance in OMPs removal. Purple fountain grass (P4) demonstrated the highest efficiency in removing OMPs and nutrients, e.g., achieving a removal efficiency (RE) of 90.6 % for diclofenac. In contrast, Vinca rosea (P3) showed the lowest with a RE of 35.5 %, while Acalypha wilkesiana (P1) and Canna indica (P2) exhibit intermediate performance. However, P4 raised microbiological concerns due to increased relative abundances of opportunistic bacterial pathogens and antibiotic resistance genes (ARGs). In contrast, P1 and P2 significantly reduced the relative abundance ARGs and mobile genetic elements (MGEs) with REs up to 97.2 %. Considering both OMPs removal and microbiological safety, P1 and P2 appear to be the most suitable options. The findings of this study shed light on plant selection criteria for nature-based biofiltration systems to achieve further polishing of reclaimed water for minimizing the presence of residual emerging contaminants.