An assessment of oestrogenicity in waste water treatment plant influent and effluent using the recombinant yeast screen assay

Abstract

The oestrogenic activity of solid phase-extracted (Empore SDB-XC disks) samples of wastewater influent and effluent in four wastewater treatment plants (WWTPs) in Ireland was estimated using the Yeast Oestrogen Screen (YES). Oestrogen activities were expressed as 17p-oestradiol equivalents (EEQ). The oestrogen activity of the effluent was reduced during treatment in the two larger WWTPs by 100% and 45%- 56% respectively, the former being equipped with an extended aeration oxidation ditch with diffused air aeration followed by chemical precipitation and the latter equipped with sequential batch reactors with UV disinfection. However the oestrogenic activity increased by 21% and 29% during treatment on two sampling occasions for a smaller older activated sludge (oxidation ditch) WWTP operating at its population equivalent and the oestrogenic activity also increased by 23% on one sampling occasion for another small WWTP with a trickling filter system operating at its population equivalent. It did, however, reduce the oestrogenicity of the influent on the second sampling occasion by 43%. This study demonstrates the varying efficiencies of the different types of treatment systems used in WWTPs. It also demonstrates the importance of the upgrading and proper maintenance of WWTPs which are operating above their capacity and are incapable of sufficiently treating influent with regard to oestrogens and oestrogen mimicking compounds.