The cleanup of polluted industrial wastewater with the aim of reusing it in the production is state-of-the-art technology From an economic point of view, interest attaches to chemical oxidation processes operating at ambient temperature, employing molecular oxygen dissolved in the wastewater as the only oxidant. and utilizing solar irradiation as the necessary activation energy. Presently, photocatalysis is the only technique meeting all these requirements The photocatalytic degradation of organic pollutants present in biologically pretreated industrial wastewater samples was investigated in a recently introduced double-skin sheet reactor using artificial as well as solar light. A significant decrease of the pollution bq organic compounds was observed.