Assessment of the treatability of wastewater from municipal wastewater treatment plants using ozone

Numerous Swiss wastewater treatment plants are currently being upgraded with an additional treatment stage to remove micropollutants from the wastewater. Alongside adsorption onto activated carbon, ozonation of wastewater is one of the most promising processes for this purpose. For certain types of effluent, however, ozonation can be problematic due to the potential formation of undesirable oxidation by-products. Such problematic effluent from wastewater treatment plants can be identified using an ozone test procedure established by the VSA. As part of the test procedure, ozonated effluent samples are analysed using bioassays. On behalf of Envilab AG, the Oekotoxzentrum has been testing wastewater from affected wastewater treatment plants for toxicity for more than 10 years using the combined algae test.