Many organic and oxidizable inorganic substances are main targets for oxidation and destruction during treatment, purification and disinfection of contaminated ground water, waste water, air, soil and waste gas and odor. Uviblox® technology uses the effects of photooxidation and photocatalytical processes by middle and low pressure UV lamps for technical systems. There are many possibilities for combination and optimisation of photooxidation with other technologies like nanotechnologies. Degradation processes can be enforced by nano structures of photocatalysts significantly. Different approaches are strongly pursued in research & development projects like NanoAqua, Fe-NANOSIT and nanoblox. These projects search for different ways of applying and handling the photocatalytical nano particles like TiO2 and ZnO. Biological surface layers, magnetite, transparent and reflecting materials are tested for suspending nano particle solids as well as for coating fixtures. Research results are very promising and economic application of nano photocatalysts in water and gas phase for purification seems likely. Any presumed ecotoxicity was not found for the examined nanoparticles so far.