Gomes Rachel L, Scrimshaw Mark D, Lester John N
Department of Earth Science and Engineering, Imperial College London, South Kensington, London SW7 2AZ, UK.
Environ Sci Technol. 2009 May 15;43(10):3612-8. doi: 10.1021/es801952h.
Steroids are excreted from the human body in the conjugated form but are present in sewage influent and effluent as the free steroid, the major source of estrogenic activity observed in water courses. The fate of sulfate and glucuronide conjugated steroid estrogens was investigated in batch studies using activated sludge grown on synthetic sewage in a laboratory-scale Husmann simulation and crude sewage from the field. A clear distinction between the fate of sulfate and glucuronide conjugates was observed in both matrices, with sulfated conjugates proving more recalcitrant and glucuronide deconjugation preferential in crude sewage. For each conjugate, the free steroid was observed in the biotic samples. The degree of free steroid formation was dependent on the conjugate moiety, favoring the glucuronide. Subsequent degradation of the free steroid (and sorption to the activated sludge solid phase) was evaluated. Deconjugation followed the first order reaction rate with rate constants for 17alpha-ethinylestradiol 3-glucuronide, estriol l6alpha-glucuronide, and estrone 3-glucuronide determined as 0.32, 0.24, and 0.35 h respectively. The activated sludge solid retention time over the range of 3-9 days had 74 to 94% of sulfate conjugates remaining after 8 h. In contrast, a correlation between increasing temperature and decreasing 17alpha-ethinylestradiol 3-glucuronide concentrations in the activated sludge observed no conjugate present in the AS following 8 h at 22 degrees C Based on these batch studies and literature excretion profiles, a hypothesis is presented on which steroids and what form (glucuronide, sulfate, or free) will likely enter the sewage treatment plant.
类固醇以结合形式从人体排出，但在污水进水和出水中以游离类固醇形式存在，这是在水道中观察到的雌激素活性的主要来源。在实验室规模的胡斯曼模拟装置中，使用在合成污水中生长的活性污泥以及现场的原污水，通过批次研究来调查硫酸酯和葡萄糖醛酸结合类固醇雌激素的归宿。在两种基质中都观察到硫酸酯和葡萄糖醛酸结合物的归宿有明显差异，硫酸化结合物更难降解，而葡萄糖醛酸去结合在原污水中更具优势。对于每种结合物，在生物样品中都观察到了游离类固醇。游离类固醇的形成程度取决于结合部分，更倾向于葡萄糖醛酸。随后评估了游离类固醇的后续降解（以及对活性污泥固相的吸附）。去结合遵循一级反应速率，17α-乙炔雌二醇3-葡萄糖醛酸、雌三醇16α-葡萄糖醛酸和雌酮3-葡萄糖醛酸的速率常数分别确定为0.32、0.24和0.35 h⁻¹。活性污泥固体停留时间在3至9天范围内时，8小时后仍有74%至94%的硫酸酯结合物残留。相比之下，观察到活性污泥中温度升高与17α-乙炔雌二醇3-葡萄糖醛酸浓度降低之间存在相关性，在22℃下8小时后活性污泥中没有结合物存在。基于这些批次研究和文献排泄概况，提出了一个关于哪些类固醇以及以何种形式（葡萄糖醛酸、硫酸酯或游离形式）可能进入污水处理厂的假设。
