Unfortunately, sewage treatment plants are not able to remove all pollutants from the wastewater. Some pollutants remain in the water despite the treatment, especially “emerging contaminants” that the treatment plants were never designed to treat. These pollutants then end up in our irrigation systems, surface waters, and more. As a result, analyzing water samples going into and leaving the sewage treatment plant for emerging contaminants is extremely important.
Heather Preisendanz, an associate professor at Penn State, and her team worked to monitor sewage treatment plants for SARS-CoV-2, the virus that causes COVID-19, and for pharmaceuticals whose usage were likely to increase during the pandemic. “We were interested in the impact the pandemic would have on the occurrence of medications entering sewage treatment plants. We also wanted to know how that would affect the quality of the treated water leaving the facilities,” says Preisendanz.
The study was published in Journal of Environmental Quality, a publication of the American Society of Agronomy and the Soil Science Society of America.
The team collected weekly samples from two sewage treatment plants. One plant covered Penn State’s University Park campus and the other, the University Area Joint Authority (UAJA) facility covered the surrounding towns, including the county’s largest hospital. They collected and analyzed samples from May 2020 to May 2021. The team was looking for the presence of SARS-CoV-2 and a variety of medications. The medications included antibiotics, over-the-counter medicines, and therapeutics.
The samples were processed quickly, such that the results could be provided in near real-time. “We were able to get the data back to the treatment plant operators and decisionmakers as quickly as possible,” says Preisendanz. This was important since one of the facilities covers the Penn State’s main campus. Some interesting relationships between data were uncovered.
Two therapeutic medications in the wastewater influent corresponded to COVID-19 hospitalizations: remdesivir and dexamethasone. Remdesivir, an anti-viral medication, was related to increases in hospitalized patients. Increased concentrations of dexamethasone coincided with the number of patients on ventilators. Both medications are used to treat hospitalized COVID-19 patients.
Unfortunately, the sewage treatment plants were unable to remove these medications from the water. As a result, they persisted in the effluent and were introduced to soils and surface waters when the treated wastewater was spray-irrigated or discharged directly to a nearby stream. More research is needed to understand how these medications may impact the environment.
Preisendanz and her team saw an increased presence in certain medications depending on the time of year. Presence of over-the-counter medications and antibiotics in the samples increased during the winter months. Seasonal trends were also observed at the UAJA facility.
“Antibiotics don’t get treated very well in most sewage treatment plants. Among the medications included in this study, the antibiotics are the biggest environmental concern, since they can lead to antibiotic resistance,” Preisendanz explains. Antibiotics aren’t directly related to COVID-19. “However, people who suffered other infections while having COVID-19 can require antibiotics,” she adds.
Over-the-counter medications, such as pain medications and fever reducers, had the highest occurrence overall. These medications are commonly used to treat many ailments, explaining the larger amounts. They are also the most effective to remove from sewage treatment plants. While over-the-counter medications were the most prevalent, they are the least persistent.
“The team is still monitoring for SARS-CoV-2 and is looking to expand to the flu and monkeypox,” Preisendanz adds. These are just a few of the possibilities that will be examined in the future.
There is so much to learn through investigating our sewage treatment plants. From community health to ecosystem health, sewage treatment plants provide valuable services and data. “People are used to hearing about emerging contaminants in our water with heightened fear,” says Preisendanz. “However, for some of these chemicals, especially the novel ones we looked at for treating COVID-19 patients, we don’t really know enough yet to understand the risk of occurrence of these chemicals in the soil and water. We also need to remember that these treatment plants are doing their jobs and working as they were intended to. They were never designed to remove these contaminants. I think trying to make sure that we talk about the benefits of sewage treatment plants and re-use of treated wastewater is important.”
This research was funded by the Penn State Institute for Sustainable Agriculture, Food, and Environmental Science.