Testing the contents of a simple sample of wastewater can reveal a lot about what it carries, but fails to tell the whole story, according to Rice University engineers.
Their new study shows that composite samples taken over 24 hours at an urban wastewater plant give a much more accurate representation of the level of antibiotic-resistant genes (ARGs) in the water. According to the Centers for Disease Control and Prevention (CDC), antibiotic resistance is a global health threat responsible for millions of deaths worldwide.
In the process, the researchers discovered that while secondary wastewater treatment significantly reduces the amount of target ARG, chlorine disinfectants often used in later stages of treatment can, in some situations, have a negative impact on water released back into the environment.
The lab of Lauren Stadler at Rice’s George R. Brown School of Engineering reported seeing levels of antibiotic-resistant RNA concentrations 10 times higher in composite samples than what they see in “grabs,” snapshots collected when flow through a wastewater plant is at a minimum.
Stadler and lead authors Esther Lou and Priyanka Ali, both graduate students in her lab, reported their results in the American Chemical Society journal Environmental Science & Technology: Water.
The results could lead to better protocols for treating wastewater to lower the prevalence of antibiotic-resistant genes in bacteria that propagate at plants and can transfer those genes to other organisms in the environment.
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