Steroidal Estrogens During Composting of Animal Manure: Persistence, Degradation, and Fate, a Review

Abstract

Different studies have shown that livestock manure has a high potential for fertilization in plant growth and crop yield. However, the main challenge of using animal manure as fertilizer is to increase the risk of endocrine-disrupting compounds (EDCs) pollution in soil and water. Because of their adverse effects, these compounds have gained more concern. Farmland applied with manure is considered the primary source of estrogens in the environment. To manage the pollution of EDCs, manure management approaches such as aerobic composting should be utilized to degrade and remove these pollutants. Composting has attracted attention because of its rapid reaction scale and strong degradation ability against the steroidal compounds. However, estrogen removal via traditional composting needs to be improved, as the steroidal compounds that remained in the composted manure could be quickly discharged to the environment because their biodegradation rate is lower than their discharge rate. For that reason, more advanced approaches, such as inoculation with microorganisms, should be involved. Also, applying adsorbent materials such as biochar (BC) and humic acid (HA) should be considered. In the light of the modern studies, affording an overall vision and perspectives about the fate of estrogens during composting is highly valuable. This review was designed to explore the sources, properties, occurrence, half-life, degradation, and transformation of estrogens during animal manure composting. Besides, the efficiency of estrogens degrading microorganisms and adsorbent additives was also reviewed. The eventual remarks were mentioned, and their prospects were discussed.