Fate, Transport, and Biodegradation of Natural Estrogens in the Environment and Engineered Systems

Abstract

Natural steroidal estrogen hormones, e.g., estrone (E1), 17beta-estradiol (E2), estriol (E3), and 17alpha-estradiol (17alpha), are released by humans and livestock in the environment and are the most potent endocrine disrupters even at nanogram per liter levels. Published studies broadly conclude that conventional wastewater treatment is efficient in the removal of 17beta-estradiol (85-99%), but estrone removal is relatively poor (25-80%). The removal occurs mainly through sorption by sludge and subsequent biodegradation. The long solids retention time in wastewater treatment systems enhances estrogen removal due to longer exposure and the presence of a diverse microbial community, particularly nitrifiers. In spite of the treatment, the effluent from conventional biological wastewater treatment systems still contains estrogenic compounds at a level that may cause disruption of endocrine systems in some species. Advanced wastewater treatment systems such as membrane processes remove the estrogen compounds mainly through physical straining of particle-bound estrogens. Another major source, which accounts for 90% of the estrogen load, is animal manure from concentrated animal-feeding operations (CAFOs). Manure is not required to be treated in the United States as long as it is not discharged directly into water bodies. Thus, there is an urgent need to study the fate of animal-borne estrogens from these facilities into the environment. A number of studies have reported the feminization of male aquatic species in water bodies receiving the effluents from wastewater treatment plants (WWTPs) or surface runoff from fields amended with livestock manure and municipal biosolids. Estrogenicity monitoring studies have been conducted in more than 30 countries, and abundant research articles are now available in refereed journals. This review paper focuses on estrogen contributions by wastewater and livestock manure, their removal rate and mechanisms in an engineered system, and their transport and ultimate fate in an engineered system and the environment. The review aims to advance our understanding of fate, transport, and biodegradation of estrogen compounds and outlines some directions for future research.

Anoxic Androgen Degradation by the Denitrifying Bacterium Sterolibacterium denitrificans via the 2,3-seco Pathway

“…Biodegradation has been proposed as a crucial mechanism for removing steroid hormones from the environment and engineered systems (12,25,26). In the last few decades, various androgen-degrading aerobic bacteria were isolated and characterized (27)(28)(29).…”

Clogging reduction and removal of hormone residues with laboratory-scale vertical flow organic-based filter and hybrid wetland

“…and the tracer recovery was 115 %. Regarding the validity of the experiments, Kadlec and Wallace (2009) refer to mass recoveries of 80-120 % as indicators of successful wetland hydraulic tracer studies.…”

“…Although the VF was continuously fed with the HF effluent, its high performance can be attributed at least partially to the fact that the substrate was not completely saturated and it contained enough oxygen to provide an oxidizing environment (Kadlec and Wallace 2009). In this sense, Pedescoll et al (2011) observed that the COD removal in shallow subsurface flow HFs could be improved if operated with filling-resting-drain phases which allowed a better aeration of the substrate.…”

“…TWs and ponds have shown to be very efficient in the removal of these emerging pollutants from wastewater with efficiencies ranging from 68 % (Song et al 2009) up to 93 % (Shappell et al 2007). In these systems, sorption and biodegradation might be the main removal mechanisms of hormone residues (Khanal et al 2006;Song et al 2009), the role of sorption being particularly important due to their low volatility and hydrophobic character (Lai et al 2000).…”

Removal of endocrine‐disrupting compounds from water using macroporous molecularly imprinted cryogels in a moving‐bed reactor

“…Although GAC is a highly adsorptive medium, the adsorption is irreversible making it difficult to regenerate the substrate [32,33]. Furthermore, its efficiency in removing E2 was found to decrease with decrease in initial concentration of E2 [34]. Regarding atrazine, 75 and 26% removal was achieved with an RT of 8 min after applying 5 L of a 10 lg/L atrazine solution to the atrazine-MIP/MGP and NIP/MGP, respectively (Fig.…”