There are more than 80 pharmaceuticals and pharmaceutical metabolites detected in the aquatic environment. Regarding negative impacts of these compounds, the main concern lays in sensitive aquatic environment and long-term effects regarding human health and the environment. Although we have procedures to assess the risk that pharmaceutical residues represent to the environment, these procedures include various assumptions and data gaps. Therefore current knowledge is not enough to say how serious the threat is that we are dealing with. Many concerned governments and organisations apply the precautionary principle (PP) regarding the potential risks that pharmaceuticals in the aquatic environment present. This means that while there is no full proof about such risks, risk management alternatives are nevertheless developed and assessed. In this thesis preventative alternatives and treatment alternatives of risk management are discussed. Preventative alternatives include source control and source separation as well as increasing awareness. Treatment alternatives include wastewater treatment both in centralised systems and decentralised systems. Current knowledge about how effective decentralised systems are in removing pharmaceuticals is not sufficient. To be able to assess the role that decentralised wastewater systems can have in risk management, pharmaceutical removal effectiveness of a bench scale recirculating biofilter (RBF) was observed in laboratory experiments. The objective was to test if a nitrifying biofilter was able to remove four selected pharmaceuticals (ibuprofen, gemfibrozil, naproxen and diclofenac) from pre-treated wastewater. According to the laboratory results, ibuprofen, gemfibrozil and naproxen were removed more than 90 percent and diclofenac was removed with approximately 70 percent efficiency. These results show that there is potential in decentralised systems regarding pharmaceutical removal. However more research is needed. Local conditions regarding pharmaceutical use patterns, water consumption, and treatment technology have an effect on determining the most efficient way to manage this environmental risk. Therefore efficient risk management includes both preventative and treatment approaches
