Removal of endocrine disrupting compounds during conventional wastewater treatment

There is evidence that aquatic organisms downstream of some sewage treatment works show endocrine disruption as a result of exposure to substances in the effluent. As a result, the Environment Agency of England and Wales, in collaboration with the UK Government and the water industry, has started an intensive programme to determine the fate and behaviour of endocrine disrupting compounds in sewage treatment works. Sampling sites for the endocrine disruption demonstration programme are located throughout England and Wales. This paper presents data from Nuneaton sewage treatment works (Warwickshire, England), a modern nitrifying activated sludge plant serving an equivalent population of 98,000 and one of the selected sites for the demonstration programme. Results for the 24-hour survey carried out in June 2006 in which manual grab samples were taken hourly show excellent removal of estrone, estradiol, nonyl-phenol and the nonylphenolethoxylates (3-5 EO units) at 97, 99, 94 and 98% respectively. They also show excellent removal (99%) of estrogenicity, measured by the YES bioassay. However the removal of ethynylestradiol was poor at only 3%. In November 2006, a further survey was carried out comprising grab samples taken at 4-hourly intervals across a continuous 7-day period. This monitoring confirmed the good removal of estrone and estradiol, at 97.8% and 96.3%, respectively as well as an excellent reduction in estrogenicity (98.37%), but again showed poor removal of ethynylestradiol of 5.6%. There was evidence of a diurnal pattern for estrone and estradiol concentrations and to a lesser extent for ethynylestradiol in samples of crude sewage with works returns. Peak concentrations tended to occur at around midday.