Assessment of the efficacy of an advanced tertiary sewage treatment plant to remove biologically active chemicals using endocrine and genotoxicity bioassays

Abstract

There has been much effort to assess the efficacy of sewage treatment plants to remove chemicals with estrogenic activity, but other modes of toxicity have received less attention. This study assessed the efficacy of advanced tertiary technologies to remove estrogen receptor (ER), aryl hydrocarbon receptor (AhR), retinoic receptor (RAR) agonists and genotoxicity using recombinant gene bioassays. Untreated sewage contained ER, AhR and RAR agonists and was genotoxic. Activated sludge treatment removed over 69% of the ER, AhR and RAR aqueous phase activities. Ozonation and biologically activated carbon processes removed genotoxicity and most receptor agonists to below detection limits. Estrogenic activity was associated with the semi-polar fraction of the aqueous phase and non-polar phase of the influent (maximum 30%). AhR and RAR activities were found in both the aqueous and particulate phases of influent. Only RAR activity was frequently found in the polar fraction of aqueous and particulate phases of the process effluent. In the influent, the greatest RAR activity was found in the polar fraction of the aqueous phase (>65%). Genotoxic activity was detected in all influent fractions but rapidly decreased. The results showed that ER, AhR and RAR agonists were greatly reduced by the advanced tertiary treatment processes.