To eliminate non-biodegradable organic compounds from wastewater application of semiconductor photocatalysis has been done. Experiments have been performed on immobilizing the photocatalyst titanium dioxide in an organic PAN microfiltration membrane and illuminated by UV-A light in order to improve oxidation performance and avoid particle separation. The organic pollutants are oxidized by in situ-produced hydroxyl radicals or directly by the catalyst. The membrane causes a convective flow of the pollutant towards the catalyst. The separation properties of the membrane can be used in a multifunctional way to extract remaining solid particles. A module containing membranes and a UV light source was developed. 4-Chlorophenol was completely mineralized at a high reaction rate. A two-step process has been developed for the clarification of highly polluted waste waters from adhesive-producing plants. First, the suspended solids which reach up to 10% of the mass stream are precipitated, flocculated and separated by means of a decanting centrifuge and flotation. Then the photocatalytic process was applied on the dissolved organic contents.