Title: Fate of 17B-estradiol in anaerobic lagoon digesters Authors
|Sikora, Lawrence -|
|Casey, Francis -|
|Larsen, Gerald -|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 9, 2013
Publication Date: N/A
Interpretive Summary: Estrogens are endocrine disrupting compounds that are constantly being eliminated in animal waste. Anaerobic lagoon digestion is a common manure management method for swine waste that is designed to produce stabilized, nutrient-rich by-product, but has not been evaluated as to the fate of estrogens. We hypothesized that anaerobic digestion would reduce the level of 17B-estradiol, the principal estrogen, in manure through microbial degradation. If true, this would provide a mechanism for reducing estrogen release into the environment via animal waste fertilization. In laboratory studies we added radioactive 17B-estradiol (E2) to laboratory-scale anaerobic digesters and monitored its fate over time. Consistent with our hypothesis, degradation of E2 did occur, which reduced the initial estrogenicity of swine waste significantly. Anaerobic digestion into methane demonstrated that a mechanism for the complete degradation of E2 existed, but more importantly, E2 was converted to estrone, a much weaker endocrine disruptor. Our findings suggest that the common practice of lagoon digestion of swine waste would reduce the entry of estrogens into the environment when compared to raw waste, and would support its use as a best management practices for manure handling.
Technical Abstract: The fate of [14C]17B-estradiol ([14C]E2) was monitored for 42 d in triplicate 10 L anaerobic digesters. Total radioactive residues (TRR) decreased rapidly in the liquid layer of the digesters and reached a steady-state value of 19-24% of the initial dose after 4 days. LC/MS/MS analyses of the liquid layer of the anaerobic digesters indicated a rapid degradation of 17B-estradiol to estrone (E1), which readily adsorbed to the sludge layer subsequent to its formation. Methane formation represented 11.1 +/- 5.7% of the initial E2 fortification with 0.3-0.5% of the staring E2 mineralized to carbon dioxide. Maximum [14C]methane production appeared between days 4-7. Estrogenicity of the final product was 2% of the original in active digesters. Estrone was the sole steroid identified under anaerobic digestion in either the liquid layer or sorbed to sludge; however, the calculated estrogenicity of the final product had been reduced 50-fold. Anaerobic digestion of swine waste has several management benefits; moreover, this study demonstrated that it reduces the potential of environmental release of estrogens, which are known endocrine disruptors.