The Laboratory of Environmental Chemistry and Biochemistry has long been concerned with the fate of substances that enter aquatic ecosystems through "treated" municipal wastewater from wastewater treatment plants. Comprehensive research at the Čežarka model site has been carried out since 2015 within two follow-up research projects of the Czech Science Foundation and CENAKVA research center. The results of the performed experiments have already been published in 13 scientific articles and presented at domestic and international conferences. The aim of the project was to describe the fate and effects of substances that are not captured by the conventional wastewater treatment process. The results of the studies suggest that the use of biological treatment in ponds of the Čežarka type is effective especially in the warmer seasons. For most of the monitored substances, there is a significant reduction of concentrations in the water, while the fish produced in such a pond meet the currently valid hygienic limits. The city of Vodňany, which provided the Čežarka pond to carry out research experiments, also has a share in the success. You can find a record of the interview with the project leader Vladimír Žlábek on the Czech Radio website.