Biodegradation of estrogenic compounds and its enhancement in a membrane bioreactor
In the project, we investigated enhancement removal of estrogenic activities in activated sludge. These activities are caused by natural and synthetic substances that mimic the effect of the human hormone estrogen and they potentially can disrupt the endocrine systems of exposed species and the reproductive systems of aquatic fauna. Human and animal wastes are a source of natural and synthetic estrogens to the environment since only a fraction is removed in conventional wastewater treatment. A yeast-based assay developed previously was modified to detect the estrogenic activity in wastewater samples. Using the assay, it was possible to quantify estrogenic activity in range equivalent to between approximately 100ng/L to 100µg/L of the female hormone 17-β estradiol (E2), with sensitivity as low as 0.03ngE2/L. The assay is therefore sensitive to the concentrations of environmental estrogens typically found in wastewater and the new assay may be a useful tool for screening for estrogenic activity. Compared to existing chemical analytical methods, the new test is simpler and covers a wider range of compounds. This is important because by-products of some of the influent estrogens are also active estrogens. For example, E2 is metabolized to estrone and estriol, which are estrogenic. Monitoring the removal of only a few substances may underestimate the estrogenic properties of treatment plant effluents and solids disposed of into the environment. Further experiments were carried out to determine the removal of estrogenic activity from water. Results show that the presence of activated sludge enhances removal of total estrogenic activity by at least 40% within 10-15 days.