Synergistic removal of pharmaceuticals and antibiotic resistance from ultrafiltered WWTP effluent: Free-floating ARGs exceptionally susceptible to degradation.

To protect the environment and human health, antibiotic resistance genes (ARGs) and persistent pharmaceuticals need to be removed from WWTP effluent prior to its reuse. However, an efficient process for removing free-floating extracellular DNA (exDNA) in combination with a wide range of pharmaceuticals is yet to be reported for real process conditions. As a possible solution, we treated real ultrafiltered WWTP effluent with UV/H 2 O 2 and combined GAC and zeolite sorption. In terms of exDNA, sequencing and high-throughput quantitative PCR (HT-qPCR) showed that exDNA is a potent carrier of numerous ARGs in ultrafiltered WWTP effluent (123 ARGs), including multi-drug efflux pump mexF that became the dominant exARG in GAC effluent over time. Due to the exposure to degradation agents, exDNA was reduced more efficiently than intracellular DNA, and overall levels of ARGs were substantially lowered. Moreover, GAC sorption was particularly effective in the removal of almost all the 85 detected pharmaceutical residues, with fresh GAC demonstrating an efficiency of up to 100%. However, zeolite (Si/Al 0.8) addition was needed to enhance the removal of persistent pollutants such as gabapentin and diclofenac to 57% and up to 100%, respectively. Our combined approach eminently decreases the hazardous effects of pharmaceuticals and antibiotic resistance in the ultrafiltered WWTP effluent, producing effluent suitable for multiple reuse options according to the latest legislation. In addition, we provided similarly promising but less extensive data for surface water and treated greywater. [Display omitted] • WWTP effluent was treated by UV/H 2 O 2 -GAC (or GAC + zeolite)-chlorination for 8 months. • Free-floating extracellular DNA was a potent ARG carrier (123 ARGs). • ExDNA was more efficiently removed than inDNA, sorption itself amplified ARGs. • Persistent micropollutants of varied polarity were removed by GAC/zeolite sorption. • AOP/sorption/chlorination synergy removed 85 pharmaceuticals and most tracked ARGs. [ABSTRACT FROM AUTHOR]