There is a growing body of evidence that many of the thousands of prescription and over-the-counter medications ultimately make their way into water bodies and drinking-water supplies. Typical wastewater treatment plants may not be effective at removing pharmaceuticals. This is because there are no regulations limiting the release of these substances in the environment and, as a result, the needed treatment technology may not have been investigated or implemented. Knowing the best treatment practices for removing pharmaceuticals from wastewater is important for protecting drinking-water supplies as well as organisms in marine and aquatic environments because many pharmaceuticals are designed to be effective at low concentrations. A new study shows that removal of pharmaceuticals from wastewater is possible, even at very low concentrations, depending on the specific treatment process, according to researchers reporting in Environmental Science: Water Research & Technology (January 2020). See also: Environmental toxicology; Freshwater ecosystem; Marine ecology; Water pollution; Water resources; Water treatment

Granular activated carbon (GAC) is used to adsorb synthetic organic chemicals, including pharmaceuticals, in the advanced water treatment process shown. Granular activated carbon is an effective adsorbent because it is a highly porous material and provides a large surface area to which contaminants may adsorb. (Credit: U.S. Environmental Protection Agency)

The 2020 study compared the removal efficiency for antidepressants, antibiotics, and common over-the-counter drugs at seven sewage treatment facilities that used differing combinations of conventional (primary and secondary) and advanced (tertiary) treatment processes by monitoring wastewater at various stages of their processes by liquid chromatography/mass spectrometry. Primary treatment uses mechanical and physical processes to separate and remove solids. Secondary (biological) treatment, such as activated sludge, uses aerobic microorganisms in biological reactors to break down organic matter. Tertiary treatment, such as oxidation using ozone (ozonation) and granular activated carbon, removes trace organic compounds that are not removed by biological processes. See also: Activated carbon; Antibiotic; Biodegradation; Liquid chromatography; Mass spectrometry; Ozone; Sewage treatment

Primary treatment did not significantly remove any of the pharmaceuticals. Secondary treatment resulted in the removal of most, but not all, of the pharmaceuticals monitored. Advanced treatment processes using ozonation and granular activated carbon proved most effective (>95 percent removal). However, bupropion (an antidepressant) and primidone (an anticonvulsant) were not affected by ozonation. In addition, ozonation may not completely degrade all compounds and may form hazardous byproducts. Still, the study shows that advanced treatment methods can be effective at removing pharmaceuticals that are able to pass through conventional treatment intact. The study could also be useful for wastewater-treatment-plant design in water-scarce regions that rely on wastewater reuse and artificial groundwater recharge for drinking water. See also: Groundwater recharge; Wastewater reuse