Eliminating medicines from wastewater
Researchers from University at Buffalo, The State University of New York, have identified two wastewater treatment techniques that are particularly effective in removing medicines from water.
Waterways in Australia and across the globe are home to a plethora of pharmaceutical compounds: painkillers, antidepressants, Alzheimer’s medication. While some chemicals can be processed by bacteria and are fairly easily removed using water purification processes, others have a chemical structure that leaves them more challenging to remove, including codeine, as well as certain antifungal treatments, antidepressants and synthetic hormones.
Pharmaceutical compounds are discharged from wastewater treatment plants and enter the environment, where they are consumed by wildlife and may contribute to problems such as antibiotic resistance. A 2018 study by Australian ecologists — published in Nature Communications — detected more than 60 pharmaceutical compounds in aquatic invertebrates and riparian spiders in six streams near Melbourne. The researchers estimated that a platypus consuming invertebrates from Brushy Creek (one of the streams included in the study) would consume about one-half of an average human daily dose of antidepressants by eating aquatic invertebrate prey from this stream.
Historically designed to remove organic matter and nitrogen from used water, wastewater treatment plants could be harnessed to remove a host of persistent pharmaceutical compounds.
A US study — examining technologies employed at seven wastewater treatment plants in the eastern United States, including six full-scale plants and one large pilot-scale plant — revealed varying results when it comes to removing medicines such as antibiotics and antidepressants.
The research, published in Environmental Science: Water Research & Technology, found that two treatment methods — granular activated carbon and ozonation — were the most promising. Each technique reduced the concentration of pharmaceutical compounds, including certain antidepressants and antibiotics, in water by more than 95%.
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 persistent drugs such as antidepressants and antibiotics.
“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, Henry M. Woodburn Professor of Chemistry in the University at Buffalo (UB) 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,” she said.
“Some cities are already doing this, but it can be expensive.”
Anne McElroy, Professor and Associate Dean for Research in the Stony Brook University School of Marine and Atmospheric Sciences, said, “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.”
Aga and McElroy led the project, with UB chemistry PhD student Luisa Angeles as first author. The paper was a partnership between researchers at UB, Stony Brook University, the Hampton Roads Sanitation District, and Hazen and Sawyer, a national water engineering firm that designs advanced wastewater treatment systems, including some of the systems studied.
Angeles explained that 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.
In terms of environmental conservation, the study observed no change in the behaviour of larval zebrafish when exposed to wastewater discharged from the treatment plants. However, Aga stated that more work is needed to understand the impact of longer-term exposure on wildlife.
In 2017, Aga’s team conducted a study, discovering high concentrations of antidepressants — or metabolised remnants — in the brains of numerous fish in the Niagara River. Aga highlighted that we still do not fully understand the behavioural and ecological consequences of long-term exposure to chemicals from human medicines that build up in wild animals over time.
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