Instream steroid hormone levels in a CAFO-impacted watershed and domestic wastewater biological removal strategies

Endocrine disrupting compounds (EDCs) are chemicals that interfere with normal hormone function, either via synthetic chemicals that act on or block normal hormonal activity or through exposure to high doses of natural hormones, such as in this study. EDCs are important because of increasing evidence linking exposure to reproductive and other health effects in humans and wildlife. Two potential sources of EDCs in the aquatic environment are confined animal feeding operations (CAFOs) and wastewater treatment plant (WWTP) discharges.; The North Bosque Watershed in North-Central Texas was studied to characterize steroid hormone levels and their relationship to land-use. The North Bosque River watershed is impacted by CAFOs, specifically dairies, and urban contributions of WWTP discharges and stormwater runoff. Water was sampled monthly for steroid hormones including 17beta-estradiol (E2), Progesterone (P), and Testosterone (T). The linear regression correlation coefficients (R2) for dairy land use verses geometric mean hormone levels generally ranged from 0.55 to 0.77. Incorporation of additional land-use variables increased the R2 values up to 0.97.; In addition, this study examined the biological treatment of these compounds using bench-scale conventional suspended growth methodologies. Decreasing the Food-to-microorganism ratio (F/M), ranging from 0.5 to 0.05 day -1 in this study, did improve hormone removal from 60--70% to 80--90% or better depending upon the target hormone.