Water contamination by micropollutnats has been increasing lately. Conventional wastewater treatment plants are not designed to efficiently remove mircopollutants, which leads to their effluent into surface water. Low concentrations of micropollutants have been detected even in drinking water. Advanced oxidation processes have shown great potential in degrading micropollutants effectively. This thesis describes selected micropollutnats, different types of advanced oxidation processes and their practical usage. In the experimental part, the effectivity of ozonation to degrade organic micropollutants is studied. In vitro bioassays utilizing cell lines hERα HeLa-9903 and CAFLUX are used in the experiments.