Fate of pharmaceutical residues - in sewage treatment and on farmland fertilized with sludge

Pharmaceutical products constitute a fundamental part of modern medicine and are in many cases crucial for health and wellbeing in our everyday life. However, the benefits from pharmaceutical come with drawbacks for the environment. These chemicals are designed to have a biological effect, which they unfortunately also might have on other living organisms than humans. They are moreover also considered to be semi-persistent due to the continuous discharge from our society. These characteristics make them problematic if they end up in the environment.

For the last ten years pharmaceutical companies on the Swedish market can choose to publish environmental information about their products on the public web-based portal www.fass.se. Prior to publication the environmental information is reviewed by an external part (IVL Swedish Environmental Research Institute). Within the context as third party reviewer, IVL also performs research to increase the knowledge of pharmaceuticals in the environment to improve the reviewing process. This report describes the Fass research study conducted in 2014 and 2015. The focus of this study was to investigate the distribution and removal of a selection of pharmaceuticals within a sewage treatment plant (STP) and their final fate in the environment. For unclear reasons residues of pharmaceuticals can be represented in higher concentration in the effluent wastewater compared to the influent, which limits correct conclusions to be drawn regarding their removal during sewage treatment.

Several studies on matrix effects and metabolism were performed to test different hypothesis that could explain the phenomena and to be able to estimate the “true” concentrations of pharmaceuticals within a STP. A mass balance was also performed to further study the pharmaceutical distribution. To assess the dispersion and fate of pharmaceuticals in the environment a farmland fertilized with sludge from the investigated STP were studied. Soil and sludge samples were analyzed as well as soil water collected by lysimeter techniques. In addition laboratory based soil sorption tests of the farmland soil exposed to pharmaceutical and sewage sludge were also performed.

The result of the study showed that analytical interferences (ion-suppression) due to competition with co-eluting matrix components during instrumental analysis was the main contributor to the observed increase in concentration of pharmaceuticals from influent to effluent wastewater, with an average ion-suppression of 49% in influent wastewater and 35% in effluent wastewater of the investigated pharmaceuticals.

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