Fate, occurrence, and removal of estrogens in livestock wastewaters

During the last decades, livestock and animal feeding operations have been expanded. In parallel, these activities are among the major sources of estrogens in the environment. Thus, considering the environmental and health risks associated with estrogenic compounds, this work reviews the fate, occurrence, and removal of free and conjugated E1, E2, and E3 in livestock wastewaters. A systematic literature review was carried out, and after applying the eligibility criteria, 66 peer-reviewed papers were selected. Results suggest high estrogen concentrations and, consequently, high estrogenic activity, especially in samples from swine farming. E1 and E2 are frequently found in wastewaters from bovine, swine, and other livestock effluents. Aerobic treatment processes were more efficient for estrogen removal, whereas anaerobic systems seem poorly effective. Removal efficiencies of estrogens and estrogenic activity of up to 90% were reported for constructed wetlands, advanced pond systems, trickling filters, membrane bioreactors, aerated and nitrifying reactors, combined air flotation, and vegetable oil capture processes. High concentrations found in wastewaters from livestock allied to the removal efficiencies reported for anaerobic processes (usually used to treat livestock wastewaters) evidence the importance of monitoring these compounds in environmental matrices.

Automated summary

In recent decades, the expansion of livestock and animal feeding operations has led to elevated levels of estrogens in the environment. This review examines the fate, occurrence, and removal of different forms of estrogens in livestock wastewaters. The results indicate high concentrations of estrogens in swine farming samples and frequent findings of E1 and E2 in wastewaters from bovine, swine, and other livestock effluents. Aerobic treatment processes are more effective in estrogen removal, while anaerobic systems show poor efficiency. Various treatment methods, such as constructed wetlands and membrane bioreactors, have been reported to remove up to 90% of estrogens and estrogenic activity. Monitoring these compounds in environmental matrices is crucial, given the high concentrations found in livestock wastewaters and the reported removal efficiencies of anaerobic processes commonly used for their treatment.