Quantitative and qualitative changes in antibiotic resistance genes after passing through treatment processes in municipal wastewater treatment plants

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>In this study, quantitative and qualitative changes in antibiotics resistance genes (ARGs) were investigated in two municipal wastewater treatment plants (WWTPs) treating pretreated livestock or industrial wastewater as well as municipal sewage. Total eight ARGs (<I>tet</I>X, <I>tet</I>M, <I>tet</I>A, <I>sul</I>1, <I>sul</I>2, <I>erm</I>B, <I>qnr</I>D, and <I>bla</I> <SUB>TEM</SUB>) were quantified, and their relative abundance was assessed by ARGs copies/16S rRNA gene copies. The fate of ARGs was observed to be different between two WWTPs: <I>sul</I>, <I>qnr</I>D, and <I>bla</I> <SUB>TEM</SUB> were proliferated during the treatment processes only in the WWTP1 which received pretreated livestock wastewater. Furthermore, dynamic shifts in patterns of ARGs occurrence were observed during biological, secondary sedimentation and coagulation processes. During biological treatment in both WWTPs, relative abundance of <I>tet</I> and <I>erm</I>B changed: <I>tet</I> increased significantly by 211.6–357.6%, while <I>erm</I>B decreased by 70.4–92.0%. Little variation was observed in <I>sul</I>, <I>qnr</I>D and <I>bla</I> <SUB>TEM</SUB>. Subsequently, the relative abundance of <I>tet</I> decreased during the secondary sedimentation and coagulation in both WWTPs: <I>tet</I> decreased by 56.0–86.3% during sedimentation and by 48.2–75.7% during coagulation, respectively. During the final treatment, different responses of antibiotic resistance bacteria (ARB) and ARGs to ultraviolet (UV) disinfection were found: removal efficiencies of ARB were observed in the range of 34–75%, while obvious reduction in ARGs was not observed at the UV dose of 27mJ/cm<SUP>2</SUP>. Although ARGs underwent various treatment processes, considerable levels of ARGs remained at discharge amounting to 4.2×10<SUP>18</SUP> copies/day from WWTP1 and 5.4×10<SUP>16</SUP> copies/day from WWTP2, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Quantitative and qualitative changes in ARGs were investigated in WWTPs. </LI> <LI> Changes were unique for each ARG community while undergoing treatment processes. </LI> <LI> Variation in ARGs was largest during biological and post-physiochemical processes. </LI> <LI> ARGs showed limited response to UV disinfection. </LI> <LI> ARB were reduced by UV disinfection. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>