De-conjugation behavior of conjugated estrogens in the raw sewage, activated sludge and river water

The fate and behavior of estrone-3-sulphate (E1-3S), estradiol-3-sulphate (E2-3S), estrone-3-glucuronide (E1-3G) and estradiol-3-glucuronide (E2-3G) were studied in raw sewage, activated sludge and river water using microcosms, and these results were compared with observations at three sewage treatment plants. The glucuronide conjugates had a half-life of 0.4 h in raw sewage, yielding 40-60% of their free estrogens. Field observations suggested complete transformation of the glucuronide conjugates in the sewer. In river water glucuronide conjugate half-lives extended to over two days yielding 60-100% of their free parent estrogens. Transformation of the sulphate conjugates in raw sewage and river water was slow with little formation of the parent estrogens. Sulphate conjugates could readily be detected in sewage influent in the field studies. In activated sludge the sulphate conjugates had half lives of 0.2 h with the transient formation of 10-55% of the free parent estrogens. Field studies indicated transformation of sulphate conjugates across the sewage treatment, although a proportion escaped into the effluent. These results broadly support the view that glucuronide conjugates will be entirely transformed within the sewer largely to their parent estrogens. The sulphate conjugates may persist in raw sewage and river water but are transformable in activated sludge and, in the case of E2-3S, reform a high proportion of the parent estrogen.