This work investigated the efficiency of a membrane bioreactor (MBR) and ozonation to remove endocrine disruptive potentials from hospital effluents. MBR treatment significantly reduces the estrogenic burden of sewage, and combined with ozone almost completely reduces estrogenicity. The occurrence of pharmaceuticals in aquatic ecosystems is related to sewage effluents. The possible adverse effects on wildlife and humans, mean that degradation and removal of pharmaceuticals and their metabolites during wastewater treatment is an increasingly important task.
This study by a large international research team is part of a proof-of-concept study at a medium-sized country hospital in western Germany, that investigated the efficiency of advanced treatment processes to remove toxic potencies from sewage.
Specifically, they assessed the efficiency of treatment processes such as a membrane bioreactor (MBR) and ozonation to remove endocrine disruptive potentials.
Estrogenic effects were characterised by use of two receptor-mediated in vitro transactivation assays: the Lyticase Yeast Estrogen Screen (LYES), and the Estrogen Receptor mediated Chemical Activated LUciferase gene eXpression (ER CALUX®). In addition, the H295R Steroidogenesis Assay (H295R) was utilised to detect potential disruption of steroidogenesis.
Raw sewage contained measurable estrogen receptor (ER)-mediated potency as determined by use of the LYES (28.9±8.6 ng/L, 0.33× concentration), which was reduced after treatment by MBR (2.3±0.3 ng/L) and ozone (1.2±0.4 ng/L).
The results were confirmed by use of ER CALUX, which measured concentrations of estrogen equivalents (EEQs) of 0.2±0.11 ng/L (MBR) and 0.01±0.02 ng/L (ozonation).
In contrast, treatment with ozone resulted in greater production of estradiol and aromatase activity at 3× and greater concentrations in H295R cells.
It is hypothesised that this is partly due to formation of active oxidised products during ozonation. Substance-specific analyses demonstrated efficient removal of most of the measured compounds by ozonation.
A comparison of the ER-mediated responses measured by use of the LYES and ER CALUX with those from the chemical analysis using a mass-balance approach, revealed estrone (E1) to be the main compound that caused the estrogenic effects.
Overall, treatment of sewage by use of MBR successfully reduced estrogenicity of hospital effluents, as well as substances that are able to alter sex steroid production. However, after ozonation, effluents should undergo further investigations regarding the formation of endocrine active metabolites.
The results obtained as part of this study demonstrate the applicability of in vitro assays for monitoring the endocrine-modulating potency of treated sewage.
