Seven sewage plants in the US have disclosed two treatment methods they use in removing prescription drugs from wastewater.
A study, conducted by researchers at the University of Buffalo, found that seven wastewater treatment plants in the Eastern US have a mixed record when it comes to removing medicines such as antibiotics and antidepressants.
The research points to two treatment methods – granular activated carbon and ozonation – as being particularly promising in the removal of these drugs. Each technique reduced the concentration of a number of pharmaceuticals in water by more than 95 per cent, the scientists’ analysis found.
According to the study, activated sludge, a common treatment process that uses microorganisms to break down organic contaminants, serves an important purpose in wastewater treatment but was much less effective at destroying these persistent drugs.
“The take-home message here is that we could actually remove most of the pharmaceuticals we studied. That’s the good news,” said Diana Aga, a chemistry professor at the university’s College of Arts and Sciences. “If you really want clean water, there are multiple ways to do it.”
“However, for plants that rely on activated sludge only, more advanced treatment like granular activated carbon and/or ozonation may be needed,” Aga added. “Some cities are already doing this, but it can be expensive.”
The findings of the study are important because any drugs discharged from treatment plants can enter the environment, where they may contribute to phenomena such as antibiotic resistance, or be consumed by wildlife. These methods can prevent these events from ever occurring.
“Our research adds to a growing body of work showing that advanced treatment methods, including ozonation and activated carbon, can be very effective at removing persistent pharmaceuticals from wastewater,” said Anne McElroy, professor and associate dean for research in the Stony Brook University School of Marine and Atmospheric Sciences.
To study pharmaceuticals in wastewater, the team used the system pictured to isolate chemical compounds from the wastewater
The research analysed a variety of technologies in use at seven wastewater treatment plants in the Eastern US, including six full-scale plants and one large pilot-scale plant. According to the paper, “more precise locations are not provided in order to protect the identity” of the facilities.
Luisa Angeles, a chemistry PhD student and first author of the paper, said the study’s findings could guide future decision-making, especially in areas where water is scarce and in cities that may want to recycle wastewater, converting it into drinking water.
The team added that the study may be vital for environmental conservation. It demonstrated that larval zebrafish did not change their behaviour when they were exposed to wastewater discharged from treatment plants. However, Aga said much more work is needed to understand how longer-term exposures may impact wildlife.
In a separate study in 2017, Aga’s team found high concentrations of antidepressants or the metabolised remnants of those drugs in the brains of numerous fish in the Niagara River, part of the Great Lakes region. Scientists still don’t fully understand the behavioural and ecological impacts that may occur when chemicals from human medicines build up in wild animals over time, Aga said.
Although wastewater treatment plants were historically designed and operated for purposes such as removing organic matter and nitrogen from used water, the new research and other prior studies demonstrate that these facilities could also be harnessed to remove different classes of medicines.
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