Effects of persulfate treatment on antibiotic resistance genes abundance and the bacterial community in secondary effluent

Secondary effluents as one of the main 'hotspots' of spreading antibiotic resistance genes (ARGs) into the environment have attracted considerable attentions. However, conventional disinfection methods may be inadequate for the successful removal of ARGs. Therefore, this study investigated the removal efficiency and the regeneration potential of ten ARGs in secondary effluent using sodium persulfate activated by Ginkgo biloba L. modified nanoscale zero-valent iron. Moreover, the role of bacterial community was not yet clear when ARGs were removed by persulfate treatment (PT). Therefore, quantitative PCR and Illumina MiSeq sequencing were applied for further exploration. The results depicted that 98.6% bacterial 16S rRNA gene was removed within 10 min. After 0.5 h PT, the removal efficiency of target ARGs decreased in the following order: Tn916/1545 = aac (below the limit of detection) > int I1 (99.99%) > tet E (99.64%) > mex F (99.10%) > tet W (94.57%) > qnr S (90.18%) > van G (82.21%) > bla-TEM (64.15%) > cat A1 (23.13%). Even upon after 48 h storage, ARGs abundances were stable. The influence of pH on ARGs removal efficiency was not significant. The results of heatmap and principal coordinate analysis depicted that the abundance of ARGs did not increase with the changes of community structure. This study revealed PT as an effective method could reduce abundance of ARGs. The ARGs carried by bacteria did not multiply in their hosts and pass on to other bacterial populations further.