A preliminary study on the occurrence and dissipation of estrogen in livestock wastewater

Livestock wastewater has high estrogen activity because animal excreta contain estrogen. In the past, when biological technologies were applied to treat livestock wastewater, the removal efficiency of estrogen pollutants was always ignored. Therefore, the efficiency of estrogen removal by anaerobic/aerobic (A/O) treatment and by up flow anaerobic sludge blanket and step-fed sequencing batch reactor (UASB-SFSBR) treatment was investigated in the present study. The results showed that the A/O treatment had no significant estrogenic removal ability, whereas the removal rates of estrogen after UASB-SFSBR treatment reached approximately 78 %, as measured by liquid chromatography and tandem mass spectrometry. The estrogen concentration decreased from 31.5 ng/L to an undetectable level according to the yeast estrogen screen analysis. We found differences between the estrogen removal rates measured by the chemical assay and those measured using the bioassay. More attention must be paid to the removal of estrogen pollutants in livestock wastewater to reduce the environmental risk.