The release of pharmaceutically active compounds (PhACs) in waste water from treatment plants (WWTPs) is currently not regulated anywhere in the world, with the exception of a few plants in Switzerland. Yet thousands of PhACs or their by-products — excreted by humans — can be found in waste water and some of these may harm biodiversity when released into waterways. For example diclofenac and oxazepam may have negative effects on aquatic species.

The unregulated release of some pharmaceuticals poses a risk to the environment, especially to aquatic species. In addition, the release of antibiotics into the environment in waste water may be contributing to the development of antibiotic resistance in potentially pathogenic bacteria. In the context of the EU Water Framework Directive (WFD):

1. a number of PhACs are listed in the first surface-water watch list established in 2015
2. under the Environmental Quality Standards Directive (EQSD)
3. Diclofenac was included to facilitate the establishment of appropriate measures to address the risk it poses, and three antibiotics also included to assess the risk they pose
4. but there are currently no EU-level environmental quality standards.

A design solution is lacking for cost-effectively removing all PhACs in large-scale WWTPs without generating unwanted breakdown products. This study presents a pilot design that seeks to deliver an alternative to less effective technologies, in particular by optimising the use of activated carbon. The Swedish study was undertaken at two WWTPs in the Stockholm region in 2015. The scientists chose 21 of the more common PhACs in waste water for further analysis, including carbamazepine, clarithromycin and diclofenac, which were used as study indicators.

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