Removal of antibiotic resistance genes in two tertiary level municipal wastewater treatment plants.
Sci Total Environ
; 643: 292-300, 2018 Dec 01.
Article
em En
| MEDLINE
| ID: mdl-29940441
ABSTRACT
Raw wastewater can contain high levels of antibiotic resistance genes (ARGs), making municipal wastewater treatment plants (WWTPs) critical for the control of the release of ARGs into the environment. The objective of this study was to investigate how individual treatment steps in two tertiary WWTPs affected the removal (copies/mL) and relative abundance of ARGs (copies/copies 16S rRNA genes). Nine ARG markers, representing resistance to commonly used antibiotics, as well as one integron gene (intl1) to assess ARG mobility potential, were quantified using quantitative real-time PCR (qPCR). Both WWTPs met provincial effluent regulations for removal of carbonaceous oxygen demand (CBOD5) and total suspended solids. Eight of the ten ARG markers (intl1, sul1, sul2, tet(O), ermB, blaCTX-M, blaTEM, qnrS) were detected in all samples. In contrast, mecA was detected intermittently and vanA remained below the detection limit in all samples. The total ARG marker abundances decreased by log 1.77 (pâ¯<â¯0.05) in the plant using an aerated lagoon (AL), and by 2.69 logs (pâ¯<â¯0.05) through treatment in the plant employing a biological nutrient removal (BNR) system. The BNR and secondary clarifier steps in both plants afforded the most removal of ARGs. The relative abundance of ARGs remained unchanged at the AL plant and showed a decreasing trend at the BNR plant. Levels of CBOD5, nitrate and the human Bacteroides fecal marker correlated with ARG concentrations, suggesting these variables may be useful in predicting ARG removal. In conclusion, the effluent coming from the WWTPs contained eight of the studied ARG markers in concentrations ranging from 0.01 to 3.6â¯logâ¯copies/mL, indicating their release into the environment, however, the relative abundance of ARGs was not enriched during treatment in the two WWTPs.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Resistência Microbiana a Medicamentos
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Eliminação de Resíduos Líquidos
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Águas Residuárias
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Genes Bacterianos
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Sci Total Environ
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Canadá