At over 90 % of the 134 recorded contaminated sites in Austria, the affected protected good is groundwater. Industrial operations and natural causes led to organic and inorganic contaminants in the soil, which subsequently infiltrate the groundwater. This thesis forms the base for the development of a new treatment process to degrade different organic contaminants in waters by using reductive and oxidative processes. For this purpose, a detailed literature research of state of the art as well as state of science was conducted. The main focus was on three “Advanced Oxidation Processes”. Upon the acquired knowledge, the degradation of the contaminants CHC (tetrachloroethene, trichloroethene and cis - 1,2 – dichloroethene), MTBE, PAH and clopyralid was determined by using the processes pro aqua (diamond electrode), EcoCan (UV) and Ferrodecont (zero valent iron). Subsequently, all processes were connected in series. Additionally, H2O2 was added and the pH was set to the scientifically – proposed optimum. A combination of all treatment processes revealed destruction of all investigated contaminants, with higher degradation rates at specific pH.