Rice University engineers find more accurate way to determine wastewater content

Engineers at Rice University have found that composite samples taken from an urban wastewater plant over 24-hours are more accurate than testing a single sample when measuring antibiotic-resistant genes (ARGs).

These researchers also found the amount of ARGs is reduced drastically by secondary treatment to wastewater, but the chlorine used in the later stages of the treatment can occasionally negatively impact the quality of the water released back to the environment.

“I think it’s intuitive that grabbing a single sample of wastewater is not representative of what flows across the entire day,” said Lauren Stadler, a faculty member at Rice-based, National Science Foundation-supported Water Treatment (NEWT) Center, in the release. “Wastewater flows and loads vary across the day, due to patterns of water use. While we know this to be true, no one had shown the degree to which antibiotic-resistant genes vary throughout the day.”

The results of this study, which was conducted at Rice's George R. Brown School of Engineering, came as the Centers for Disease Control and Prevention (CDC) called antibiotic resistance "a global health threat" that has caused millions of deaths around the world, the release stated.

Stadler, along with graduate students Esther Lou and Priyanka Ali, were the lead authors of this research. The team's discovery could be the starting point for new industry protocols when it comes to how wastewater is treated and how to reduce ARG levels, the release noted. Stadler called antibiotic resistance "critical" since it's responsible for 2.8 million infections and 35,000 deaths in the United States alone. 

By gathering samples, the researchers learned that ARG was mostly removed by biological processes, instead of chemical disinfection and that the use of chlorine as a final treatment before the water is released back into the environment "may have selected for antibiotic-resistant organisms," according to the release.