The Removal of Estrogens in Different Dairy Manure Treatments

The effects of three manure treatments on estrogen removal (E2 and E3) were examined in this study. Samples were taken from a full-scale manure handling system incorporating manure separation and aeration (System I), an anaerobic digester receiving dairy manure (System II), and anaerobic slurry from three commercial dairy farms (System III). E2 and E3 were analyzed using enzyme-linked immunosorbent assay (ELISA). Significant differences were found in the ratios of estrogens to total solids in land-applied manure among the three treatment systems (P < 0.05), with System II yielding land applied material of the highest estrogen content. System I significantly reduced the total mass of E2 and E3 found in land applied material compared to the influent (P < 0.05). The upstream solid separation process in this system did not remove E2 or E3; all removal by the system was due to the downstream sequential aeration process. The mass of E2 (P < 0.05) but not E3 (P > 0.05) was significantly decreased in System II, although it is unclear whether this removal was due to biodegradation or sorption to sludge. Future work will focus on this question, as well as the effect of treatment on total estrogenic activity. Manure treatment systems designed for nutrient management purposes also influence the estrogen content of land applied waste.