2-Hydroxyibuprofen and carboxyibuprofen were identified in this study as ibuprofen TPs. Both have been reported as human metabolites [28] and as major TPs of ibuprofen in biofilm reactors [29] and activated sludge [30]. Their behavior in this study agreed with observations by other authors [18,21,30], i.e. both TPs decreased to concentrations below the limit of detection (LOD) at the end of the incubation period when ibuprofen was completely eliminated. This implicates a low persistence of both TPs in the water/sediment system.