The aim of this preliminary investigation was to verify the possibility of increasing the photoactivity of semiconductors, such as TiO2 and ZnO, with the goal to minimize the volume of slurry-photoreactors to be used in wastewater treatment.The enhancement of photocatalytic activity has been reached through the doping of ZnO and TiO2 nanoparticles with nitrogen and supporting them on ZnS-based luminescent microparticles (phosphors).The coupling of ZnS-based phosphors with N-TiO2 and N-ZnO leads to an increase of the photocatalytic reaction rate in removal of organic dyes from wastewater allowing to reach the process intensification for the large scale design of a photocatalytic system.