The spread of pharmaceutical residues in aquatic environments constitutes a growing environmental concern affecting both aquatic and terrestrial ecosystems through bioaccumulation and toxic effects. Pharmaceuticals are classified as organic micropollutants and are characterizedby chemical structures that are often resistant to degradation, allowing them to pass through conventional wastewater treatment processes. To reduce emissions of organic micropollutants, the European Union (EU) has introduced a revised Urban Wastewater Treatment Directive with stricter requirements for the removal of pharmaceutical residues. To meet these requirements, the Henriksdal Wastewater Treatment Plant has established a pilot facility consisting of several treatment lines to evaluate the removal efficiency of granular activated carbon (GAC) filtration and a combined ozonation–GAC treatment process for pharmaceutical residues. Different ozone doses were tested to identify an optimal dose from a resource-efficiencyperspective while ensuring effective degradation of organic micropollutants. Through sampling and subsequent analyses, concentrations of organic micropollutants were compared between influent wastewater and effluent water from the treatment lines. In addition to the pharmaceutical substances included in the directive, per- and polyfluoroalkyl substances (PFAS) and toxicity were also analyzed. Toxicity analyses were conducted to ensure that ozonation did not lead to the formation of toxic by-products, while PFAS were included because they also constitute organic micropollutants whose presence in wastewater should be reduced. Analyses of pharmaceuticals, PFAS, and toxicity were performed by external laboratories. The aim of this thesis was to evaluate the effectiveness of these treatment methods for the removal of organic micropollutants. Due to delays in analytical results, the adsorption of pharmaceutical residues onto GAC could not be fully evaluated. However, the results demonstrated that ozonation reduced the occurrence of pharmaceutical residues in wastewater. PFAS compounds were adsorbed onto the GAC filter, indicating that the technology may contribute to reducing emissions of several types of organic micropollutants. The findings suggest that ozonation combined with GAC filtration is a promising method for future quaternary wastewater treatment and may contribute to meeting the requirements of the EU's revised Urban Wastewater Treatment Directive.