Discharge of hospital wastewater is of increasing concern, as hospitals are identified as chemical pollution source due to pharmaceutical content. This project seeks to develop the most efficient and economically feasible technology to remove pharmaceuticals from wastewater, regardless of the point of treatment: at the hospital or at the treatment plant. So far, two biofilm-based technologies are discussed: MBBR and HYBAS. Introduction Considering wastewater treatment, hospital wastewater represents a substantial source of pharmaceuticals. Classical wastewater treatment plants are generally inefficient in the removal of micropollutants (i.e. pharmaceuticals). Consequently, on-site treatment of hospital wastewater has been suggested in Denmark as well as in other countries. However, no technology is yet available to efficiently remove pharmaceuticals from wastewater in a cost-and energy efficient way. This holds for at source treatment (at the hospital), or at the municipal treatment plant. Membrane-BioReactors (MBR) reverse osmosis and ozone have been used in several European pilot projects for separate hospital treatment (e.g. Nielsen et al. 2012), but this technology is costly to construct and complicated by expensive membrane cleaning. Moving-Bed-Biofilm-Reactors (MBBR) used in stages has successfully been applied to treat wastewater from pharmaceutical and other industries and staged biofilm reactors generally achieve much lower DOC effluents than activated sludge systems. Recently, it was demonstrated that biofilms from a MBBR-system used for municipal nitrification have far better ability to degrade recalcitrant pharmaceuticals than activated sludge (Falås, 2012). In this study, two different parallel-staged MBBR systems were compared with two objectives: (a) maximum removal of problematic pharmaceuticals (risk minimization) and (b) minimization of residual dissolved organic carbon (cost minimization) prior to ozonation. System 1 was operated as a pure MBBR system, whereas system 2 was operated as a hybrid process with MBBR carriers and activated sludge, termed HYBAS.