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Can we remove estrogens from dairy manure during storage? Zunyang Zhao and Dr. Katharine F. Knowlton, Dept of Dairy Science Dr. Nancy G. Love, Dept of Civil & Environmental Engineering Dr. Katharine Knowlton Department of Dairy Science [email protected] Methods Significant estrogens have accumulated in the environment and are of concern because of their potent endocrine disrupting effects. While most research has focused on estrogens and other endocrine disrupting compounds in wastewater treatment plants, 49 tons of estrogens are excreted annually from livestock farms in the US, with dairy cattle contributing the majority. The effects of three manure treatments on removal of 17-b estradiol (E2) and estriol (E3) were examined in this study. Samples were taken from a full-scale manure handling system (manure separation and aeration), an anaerobic digester, and anaerobic slurry from three commercial dairy farms. Significant differences were found in the ratios of estrogens to total solids in land-applied manure, with the anaerobic digester yielding land applied material of the highest estrogen content. In this system mass of E2 but not E3 was decreased by treatment. Virginia Tech’s separation/aeration system reduced the total mass of E2 and E3 in land applied manure compared to the influent. Estrogens can be removed from dairy manure during storage and treatment. Flushed dairy manure samples were collected monthly from a manure handling system receiving manure from about 140 dairy cows at the Virginia Tech Dairy Center. The influent and effluent of an anaerobic digester were collected on Mason-Dixon dairy farm (2,400 cows). Anaerobically stored manure slurry samples were collected from three other commercial dairy farms during fall land application. The concentrations of 17β-estradiol (E2) and estriol (E3) in the samples were assayed with ELISA after a newly developed two-step extraction. The 140 cow Virginia Tech Dairy Center (above), and 2,400 cow Mason-Dixon farm (below) Toluene extraction Evaporation ELISA (B) 120 MS FW P < 0.05 E3 (mg/d) 100 E2 (mg/d) 50 b b 1 2 3 Figure 3. Calculation of the ratio (ng/g) of E2 to total solids in land-applied manure indicates relatively greater estrogenicity in anaerobic digester effluent (System 1) vs commercial dairies (2) and the VT aeration system (3). • There is significant estrogen removal in manure treatment systems. 80 60 40 80 MS FW P < 0.05 60 40 Because dairy cattle are such a potentially significant source of environmental estrogens, much more work is merited in this area. Remaining questions include: 20 0 0 Fall Winter Spring Summer Fall Winter Spring Summer Figure 1. Calculation of daily flows at the VT Dairy indicates consistent removal of both E2 (A) and E3 (B). MS: main slurry; FW: flush water. (A) 6 Influent Effluent 5 P < 0.05 (B) 4 Influent Effluent 3 E3 (g/d) 4 3 E2 (g/d) 2 NS: P > 0.05 0 0 Fall Winter Spring • Whether observed estrogen removal is due to estrogen degradation or to sorption. • The fate of conjugated estrogens in manure treatment systems; and • The effect of treatment on total estrogenic activity. Acknowledgements • The authors appreciate the financial support of the Virginia Water Resource Research Center and fellowship support for Zunyang Zhao from the John Lee Pratt Foundation. 2 1 1 • Greater estrogen removal was observed in aerobic conditions. Limitations and future work 20 Estrogen removal was quantified in different manure treatment systems using an accurate and sensitive method. This will be helpful in designing systems to achieve both nutrient and estrogen removal in livestock manure. 100 • Our method for manure estrogen quantification is an improvement over previous approaches. Findings Implications 150 Summary . (A) a 0 Estrogen extraction and analysis NaOH & Centrifugation Chloroform Objectives To develop an appropriate method for manure estrogen analysis and to quantify estrogen removal in dairy manure treatment systems. 200 E2/TS (ng/g) Abstract/Background Fall Winter Spring Figure 2. E2 removal (A) was also observed in the anaerobic digester, but there was no effect on E3 (B). • We appreciate the technical assistance of Dr. Chao Shang, Marcus Hollmann, Wendy Wark, Cathy Parsons, Jody Smiley, and Dick Waybright.