Improvement of wastewater and water quality via a full-scale ozonation plant?-A comprehensive analysis of the endocrine potential using effect-based methods

Micropollutants (MPs), especially endocrine disrupting compounds (EDCs), are mainly released from WWTPs into surface water bodies and can subsequently lead to adverse effects in biota. Treatment with ozone proved to be a suitable method for eliminating such MPs. This method was implemented at the WWTP Aachen-Soers by commissioning the largest full-scale ozonation plant in Europe at the moment. Recently, effect-based methods (EBMs) have been successfully proved for compliance monitoring, e.g. estrogenic compounds. Therefore, the impact of ozone treatment on endocrine potential (agonistic and antagonistic) of treated wastewater was investigated using the ER alpha- and AR CALUX assays. Additionally, the impact on the receiving stream and a potential preload of the water body was assessed. Therefore, the current study could deal as a case study for small rivers being highly impacted by WWTPs. The estrogenic potential was nearly fully eliminated after ozone treatment. Contrary, the antagonistic (anti-estrogenic and anti-androgenic) potential did not show a clear elimination pattern after ozone treatment independent of the applied ozone dosage and control system. Therefore, further investigations are required regarding the antagonistic potential. Additionally, preloading of the receiving stream was found during the study period. One significant impact is a rain overflow basin (ROB) located upstream of the WWTP effluent. The highest endocrine potential was found after a ROB overflow (2.7 ng EEQ/L, 2.4 mu g TMX-EQ/L, 104 mu g FLU-EQ/L), suggesting that such runoff events after a heavy rainfall may act as a driver of endocrine loading to the water body. This manuscript contributes significantly to the basic understanding of the efficiency of eliminating the endocrine po-tential of ozone treatment by, e.g., showing that there is a further need for improving the removal efficiency of antagonistic potential. Moreover, it highlights the need to include other point sources, such as ROBs, to assess pol-luted surface waters comprehensively. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the impact of ozone treatment on endocrine potential in treated wastewater, finding that the estrogenic potential was nearly fully eliminated while the antagonistic potential did not show a clear elimination pattern. Further investigation is required regarding the antagonistic potential. Additionally, a significant impact was found from runoff events, such as those from rain overflow basins (ROBs), suggesting a need to comprehensively assess polluted surface waters by including other point sources.