Do we underestimate the concentration of estriol in raw municipal wastewater?

Deconjugation potentials of natural estrogen conjugates in sewage and wastewater treatment plant: New insights from model prediction and on-site investigations

Natural estrogen conjugates play important roles in municipal wastewater treatment plant (WWTP), but their deconjugation potentials are poorly understood. This work is the first to investigate the relationships between the enzyme activities of arylsulfatase/β-glucuronidase and deconjugation potentials of natural estrogen conjugates. This work led to three important findings. First, the enzyme activity of β-glucuronidase in sewage is far higher than that of arylsulfatase, while their corresponding activities in activated sludge were similar. Second, a model based on β-glucuronidase could successfully predict the deconjugation potentials of natural estrogen glucuronide conjugates in sewage. Third, the enzyme activity of arylsulfatase in sewage was too low to lead to evident deconjugation of sulfate conjugates, which means that the deconjugation rate of estrogen sulfates can be regarded as zero. By comparing their theoretical removal based on enzyme activity and on-site investigation, it is reasonable to conclude that reverse deconjugation of estrogen conjugates (i.e., conjugation of natural estrogens to form conjugated estrogens) likely exist in WWTP, which explains well why natural estrogen conjugates cannot be effectively removed in WWTP. Meanwhile, this work provides new insights how to improve the removal performance of WWTP on natural estrogen conjugates. SYNOPSIS: This work is the first to show how arylsulfatase/β-glucuronidase could affect deconjugation of natural estrogen conjugates and possible way to enhance their removal in wastewater treatment plant.

Twelve natural estrogens in urines of six threatened or endangered mammalian species in Zoo Park: implications and their potential risk

This work was the first to report twelve natural estrogens (NEs) in the urines of six threatened or endangered mammalians in a Zoo Park of Guangzhou (i.e., panda, gorilla, elephant, African lion, jaguar, and leopard). Ten out of twelve NEs were detected at least in one urine sample of the six mammalians studied, including the four major NEs (i.e., estrone (E1), 17β-estradiol (E2), 17α-estradiol (αE2), estriol (E3)), and six other NEs (i.e., 4-hydroxyestrone (4OHE1), 2-hydroxyestradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 16α-hydroxyestrone (16α-OHE1), 16ketoestradiol (16ketoE2), and 17epiestriol (17epiE3)). The six studied mammalians, ranked in the order of high to low urinary concentration of total NEs, were jaguar, African lion, gorilla, elephant, panda, and leopard, with respective urinary concentrations of 110.4, 86.4, 71.4, 66.0, 55.9, and 52.8 ng/mL. According to the average urinary concentration of NE in the six mammalians ranked from high to low, the top five NEs detected were 16α-OHE1, 4OHE1, E1, E3, and 17epiE3, respectively. These clearly indicated the occurrence of NEs other than the four major types in urines of animals in a Zoo Park. Moreover, the daily excretion rates of the five detected NEs by one elephant ranged from 1162-2254 μg/d with a total daily excretion rate of 8260 μg/d, suggesting that the total urinary excretion of NEs by one adult elephant was equivalent to that by 170 premenopausal women or 506 adult men. Consequently, it appears from this study that NEs in the urines of zoo animals should be considered an emerging source of NEs.

Removal of estrogen pollutants using biochar-pellet-supported nanoscale zero-valent iron

Nanoscale zero-valent iron-supported biochar pellets (nZVI)-(BP) were synthesized via liquid-phase reduction and applied to estrogen removal, including estrone (E1), 17β-estradiol (E2), and estriol (E3). The performance of nZVI-BP, with respect to its characterization, removal kinetics, and isotherms, was investigated. The results showed that the adsorption equilibrium was reached within 10 min of exposure. The adsorption capacity of estrogen decreased with increasing solute pH and nZVI-BP dosage. The adsorptivity increased with increasing initial estrogen concentration. The estrogen behavior followed a pseudo-second-order kinetic model. The adsorption data of different initial estrogen concentrations fitted to Freundlich adsorption isotherms. In addition, a preliminary discussion of the adsorption mechanism of nZVI-BP for estrogens was provided.

Photocatalytic activity of micron-scale brass on emerging pollutant degradation in water: mechanism elucidation and removal efficacy assessment

Alloys or smelted metal mixtures have served as cornerstones of human civilization. The advent of smelted copper and tin, i.e., bronze, in the 4^th millennium B.C. in Mesopotamia has pioneered the preparation of other metal composites, such as brass (i.e., mixture of copper and zinc), since the bronze age. The contemporary use of these alloys has expanded beyond using their physical strength. The catalytic chemistry of micron-scale brass or copper–zinc alloy can be utilized to effectively degrade emerging contaminants (ECs) in water, which are presenting significant risks to human health and wildlife. Here, we examine the photocatalytic activity of a commercially available micro-copper–zinc alloy (KDF® 55, MicroCuZn), made with earth abundant metals, for oxidative removal of two ECs. The micron-scale brass is independently characterized for its morphology, which confirms that it has the β-brass phase and that its plasmonic response is around 475 nm. Estriol (E3), a well-known EC, is removed from water with ultraviolet (UV) radiation catalyzed by MicroCuZn and H₂O₂–MicroCuZn combinations. The synergy between H₂O₂, UV, and MicroCuZn enhances hydroxyl radical (˙OH) generation and exhibit a strong pseudo-first-order kinetic degradation of E3 with a decay constant of 1.853 × 10⁻³ min⁻¹ (r² = 0.999). Generation of ˙OH is monitored with N,N-dimethyl-4-nitrosoaniline (pNDA) and terephthalic acid (TA), which are effective ˙OH scavengers. X-ray photoelectron spectroscopy analysis has confirmed ZnO/CuO–Cu₂O film formation after UV irradiation. The second EC studied here is Δ9-tetrahydrocannabinol or THC, a psychotropic compound commonly consumed through recreational or medicinal use of marijuana. The exceptionally high solids–water partitioning propensity of THC makes adsorption the dominant removal mechanism, with photocatalysis potentially supporting the removal efficacy of this compound. These results indicate that MicroCuZn can be a promising oxidative catalyst especially for degradation of ECs, with possible reusability of this historically significant material with environmentally-friendly attributes.

Micron-scale brass is a catalyst that can be activated with ultraviolet radiation to remove emerging contaminants from water via oxidation by hydroxyl radicals.

Trace determination of eleven natural estrogens and insights from their occurrence in a municipal wastewater treatment plant and river water

As endocrine disruptors, natural estrogens including estrone (E1), 17β-estradiol (E2), and estriol (E3) in wastewaters of municipal wastewater treatment plant (WWTP) as well as other environmental matrix have been widely studied. However, the far-less studied natural estrogens such as 2-hydroxyestrone (2OHE1), 16α-hydroxyestrone (16α-OHE1), 4-hydroxyestrone (4OHE1), etc., found in human urine have been almost ignored. Therefore, it is important to investigate the occurrence of these far-less studied natural estrogens in municipal WWTP and other environment. In this study, a GC-MS analytical method was firstly established and validated for trace determination of eleven natural estrogens in waste and surface waters, including E1, E2, E3, 2OHE1, 16α-OHE1, 4OHE1, 2-hydroxyestradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 17-epiestriol (17epiE3), 16-epiestriol (16epiE3), and 16keto-estradiol (16ketoE2). All the eleven natural estrogens were detected in the influent of one municipal WWTP, which ranged from 7.9 to 62.9 ng/L. The top five natural estrogens in the influent were E1, E3, 16α-OHE1, 16ketoE2, and 2OHE1 with respective concentrations of 62.9, 62.6, 46.9, 32.7, and 28.8 ng/L. Most of them were detected in both the effluent and river water, in which their detected concentrations were n.d-14.7 and n.d-51.7 ng/L, respectively. This work is the first to indicate that the so far less commonly studied natural estrogens in the environment likely pose adverse health effect on humans and wildlife due to their relative strong estrogenic potencies and high levels in wastewater and river water. More work should be done to understand their removals in municipal WWTPs and their occurrence in surface waters.

Can high rate algal ponds be used as post-treatment of UASB reactors to remove micropollutants?

The present study evaluated the removal capacity of a UASB-HRAP treatment system, combining anaerobic and microalgae-based, aerobic treatment, for eleven organic micropollutants present in raw sewage, including pharmaceuticals, estrogens and xenoestrogens. The UASB reactor and the HRAP were operated at a hydraulic retention time (HRT) of 7 h and 8 days, respectively. Influent and effluent samples from the UASB and HRAP were collected periodically. All the target compounds were detected in raw sewage, with an occurrence ranging from 70 to 100%. Removal rates in the UASB reactor were generally incomplete, ranging from no removal (-25.12% for the hormone EE2-ethinylestradiol) to 84.91% (E2 - estradiol). However, the overall performance of the UASB + HRAP system was highly efficient for the majority of the compounds, with removal rates ranging from 64.8% (ibuprofen) to 95% (estrone). Gemfibrozil and bisphenol A were the only exceptions, with overall removal rates of 39% and 43%, respectively. Hormones were the compounds with the highest removal rates in the system.

Human exposure of bisphenol A and its analogues: understandings from human urinary excretion data and wastewater-based epidemiology

This work evaluated human exposure to bisphenol A (BPA) and its analogues based on human urinary excretion data and wastewater-based epidemiology (WBE). The results showed that the world's average human daily intake ranked from high to low is in order of bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS), bisphenol P (BPP), bisphenol AP (BPAP), bisphenol B (BPB), bisphenol Z (BPZ), and bisphenol AF (BPAF), and their corresponding human daily intakes are 2.53, 0.68, 0.60, 0.41, 0.36, 0.29, 0.24, and 0.06 μg/p/day, respectively. BPA is clearly the dominant bisphenol for human exposure. However, the results also showed that humans have been widely exposed to BPA analogues as well. Many BPA analogues showed similar estrogenic activities to those of BPA; therefore, the adverse effects of BPA and its analogues on humans should be comprehensively evaluated. The nominal exposure levels obtained based on wastewater-based epidemiology ranked high to low are in order of BPA (513.73 μg/p/day), BPF (10.20 μg/p/day), BPS (5.21 μg/p/day), BPP (1.15 μg/p/day), BPZ (0.66 μg/p/day), BPB (0.61 μg/p/day), BPAF (0.58 μg/p/day), and BPAP (0.35 μg/p/day). The world's human average daily intakes of BPA and its analogues are only 0.5-47.9% of the intakes of their corresponding human nominal exposures. This study suggests that other sources rather human excretions are important origins in municipal wastewater, which indicates that the WBE method based on parent compounds is inappropriate for evaluations of human daily intakes of BPA and its analogues, neither for other industrial compounds that have multiple important sources. Three main important sources of BPA and its analogues in municipal wastewater are likely effluents of industrial wastewater, discharges of hospital wastewater, and landfill leachates. To decrease discharges of BPA and its analogues to the natural environment, any mixing of industrial and hospital wastewater as well as landfill leachates in municipal wastewater is not favorable.

Insights into removal mechanisms of bisphenol A and its analogues in municipal wastewater treatment plants

The occurrence and removal mechanisms of bisphenol A (BPA) and its analogues in municipal WWTPs were critically reviewed in this article. BPA appeared to be the dominant bisphenol, and the removal efficiency of bisphenols was in the order of bisphenol AP>bisphenol P>bisphenol F>bisphenol Z>bisphenol C>bisphenol S>bisphenol B>BPA>bisphenol E>bisphenol AF. It was also found that BPA removal showed linear relationships to those of its analogues, which have been proven by BPA vs BPS or BPF. BPA removal performances in different treatment processes ranked from low to high are primary treatment, lagoon process, biological aerated filter, and activated sludge. Lab-scale studies showed that >50% BPA can be removed by sewage sludge estimated with the BPA solid water distribution coefficients, which showed that sludge adsorption played an important role on BPA removal. The theoretically predicted removal of BPA in municipal WWTP showed that it is readily biodegradable, which deviate from its on-site investigations. Existence of BPA conjugates in raw municipal wastewater as well as newly produced BPA degraded or migrated from microplastic materials are possible two main reasons.

Trace determination of sulfonamide antibiotics and their acetylated metabolites via SPE-LC-MS/MS in wastewater and insights from their occurrence in a municipal wastewater treatment plant

Antibiotics have drawn much attention as their wide usage in humans and animals may result in microbial resistance, which is a huge threat to humans' health. Studies on the occurrence and removals of antibiotics in wastewater treatment plants have been widely performed, but very few covered their main acetylated metabolites. This study developed an effective analytical method for the trace determination of four sulfonamides and three acetylated metabolites in municipal wastewaters, which was validated by linearity (R² > 0.995), sensitivity (limit of quantification, LOQ < 0.78 ng/L), recovery (77.7%-148.1%) and precision (relative standard deviation, RSD < 9.6%). All sulfonamides and their acetylated metabolites were detected in municipal wastewaters including influent, primary settling tank and effluent. Removal performances of sulfapyridine (SP), sulfadiazine (SDZ), sulfamethoxazole (SMZ), and N₄-acetyl sulfadiazine (AC-SDZ) in the municipal wastewater treatment plant were moderate or excellent, whereas the corresponding removals of sulfamethazine (SM2), N₄-acetyl sulfapyridine (AC-SP), and N₄-acetyl sulfamethazine (AC-SM2) were poor. The calculated poor removal of SM2 might be attributed to its fluctuation in raw wastewater, whereas the poor removals of AC-SP and AC-SM2 may be due to re-transformation from their parent sulfonamides. Our results showed that monitoring of acetylated sulfonamides in municipal wastewater is important for two reasons. One is that acetylated metabolites are good biomarkers for wastewater-based epidemiology when they are combined with their corresponding parent sulfonamides. The other is that the potential risk of sulfonamides in effluent to the natural environment cannot be accurately evaluated unless their acetylated metabolites are also accounted. This report is the first to address the potential risk of acetylated sulfonamides in effluent of wastewater treatment plants.

Occurrence, removal and risk assessment of steroid hormones in two wastewater stabilization pond systems in Morogoro, Tanzania

The present study investigated the occurrence and removal of 10 steroid hormones (4 androgens, 3 progestagens and 3 estrogens) in two WSP systems, Mafisa and Mzumbe in Morogoro, Tanzania. All 10 steroid hormones were detected in the influent of both WSP systems in the dry as well as in the rainy season. The concentrations of steroids in influent wastewater ranged from 0.1 ng/L for 17-OH-pregnenolone to 445 ng/L for estrone and from below limit of detection for 17-OH-pregnenolone to 45 ng/L for estrone in effluent. During dry season, the overall mean ± standard deviation removal efficiency for the 10 steroids were 70 ± 21% for Mzumbe WSP and 97 ± 3% for Mafisa WSP. During the rainy season the overall mean removal efficiency for all the steroid hormones were 52 ± 32% for Mzumbe WSP and 94 ± 8% for Mafisa WSP. Risk was characterized by calculating the risk quotients (RQs) for fish and humans. 46% of the total RQs calculated were above one, indicating high risk. Low RQs were estimated for androgens and progestagens but the estrogen concentrations measured in the WSP systems and Morogoro River indicated a high risk for fish. However, estrogens appeared not to pose an appreciable risk to human health from water intake and fish consumption. The results indicated that WSP systems are quite effective in removing steroid hormones from wastewater. Thus, low technology systems such as WSP systems are suitable techniques in low income counties due to relatively low costs of building, operating and maintaining these systems.

Fast trace determination of nine odorant and estrogenic chloro- and bromo-phenolic compounds in real water samples through automated solid-phase extraction coupled with liquid chromatography tandem mass spectrometry

A fast and reliable method was developed for simultaneous trace determination of nine odorous and estrogenic chloro- and bromo-phenolic compounds (CPs and BPs) in water samples using solid-phase extraction (SPE) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). For sample preparation, the extraction efficiencies of two widely applied cartridges Oasis HLB and Sep-Pak C18 were compared, and the Oasis HLB cartridge showed much better extraction performance; pH of water sample also plays important role on extraction, and pH = 2-3 was found to be most appropriate. For separation of the target compounds, small addition of ammonium hydroxide can obviously improve the detection sensitivity, and the optimized addition concentration was determined as 0.2%. The developed efficient method was validated and showed excellent linearity (R ² > 0.995), low limit of detection (LOD, 1.9-6.2 ng/L), and good recovery efficiencies of 57-95% in surface and tap water with low relative standard deviation (RSD, 1.3-17.4%). The developed method was finally applied to one tap and one surface water samples and most of these nine targets were detected, but all of them were below their odor thresholds, and their estrogen equivalent (EEQ) were also very low.

Worldwide human daily intakes of bisphenol A (BPA) estimated from global urinary concentration data (2000-2016) and its risk analysis

To evaluate BPA's potential risk to health, it is important to know human daily intake. This study describes a simple but effective method to estimate the levels of human BPA intake among four different populations based on urinary concentration data. Nationally, of the 30 countries examined, the top ten countries for adult intake were Italy, Sweden, Denmark, France, Cyprus, Australia, Israel, Ghana, Jamaica, and Belgium. When the urinary excretion sample size was large enough and over 1000, it was found that the national estimated BPA daily intakes in the child group among countries, showed a good linear relationship with those of their corresponding adult group. Except the infant group with limited data, the global estimated BPA daily intakes for children and pregnant women were 2 and 1.4 times that of the adult group. Although the national and global estimated BPA daily intakes were generally below the temporary tolerable daily intake (tTDI) recommended by the European Food Safety Authority (EFSA), but some normal individuals' daily intakes exceeded the tTDI.

Resource efficiency analysis for photocatalytic degradation and mineralization of estriol using TiO2 nanoparticles

A resource efficiency analysis was developed that evaluated photocatalyst loading and temperature inputs, and assessed hydroxyl radical (OH) production. Catalyst loading (Aeroxide^® TiO₂ P25) between 1 and 1500 mg L^-1 and temperatures between 5 and 50 °C were analyzed as input resources for OH production. After, the best experimental conditions were used to degrade and mineralize estriol (E3). The analysis showed that a low catalyst concentration lead to poor absorption of radiation and a slow reaction. When high catalyst concentrations were tested, most of the radiation was absorbed, which produced results near the top of the slowing rate of OH generation. Temperature was found a relevant resource for increasing interfacial transfer to facilitate OH production following the Arrhenius model. Two indices to measure resource efficiency were proposed: 1) the OH generation index (OHI) and 2) the initial degradation efficiency (IDE). OHI was used to measure the efficiency of a catalyst using photonic flux to generate OH production. IDE evaluated the relationship between the photocatalytic reactor set-up, catalyst, and E3 degradation. It was observed that 1.18 OH was produced when a photon interacts with a photocatalyst particle when a load of 5 mg L^-1 of photocatalyst is used at 20 °C. It was found that at initial time, 2.4 OH was generated in the systems to produce a degradation of one E3 molecule when using a photocatalyst load of 20 mg L^-1 at 20 °C. Additionally, it was demonstrated that E3 mineralization was feasible under different catalyst loading scenarios.

Investigation of full-scale ozonation at a municipal wastewater treatment plant using a toxicity-based evaluation concept

Effluents from municipal wastewater treatment plants (WWTPs) are known to be point sources of micropollutants for surface waters. The aim of this study was to examine a reconstructed full-scale ozonation equipped with a pump-injector system for ozone (O₃) dosage and a fluidized moving-bed reactor as biological posttreatment at a municipal WWTP utilizing an effect-directed approach. This approach consists of chemical analysis in combination with toxicological tests for the assessment of treatment efficiency of the plant. Chemical analysis showed elimination rates > 80% for pharmaceuticals and industrial chemicals. Analysis of endocrine disruptors was limited due to substance concentrations below the limit of detection (LOD). Estrogenic activity was detected by the Arxula Adeninivorans yeast estrogen screen (A-YES) at low concentrations (pg to ng EEQ/l range). Estrogenic activity was reduced by more than 90% after ozonation. In contrast, androgenic activity (measured in the Adeninivorans yeast androgen screen, A-YAS) was still found after O₃ treatment and after biological posttreatment, which is consistent with the data obtained by chemical analysis. Furthermore, no marked genotoxic or cytotoxic effects were observed after ozonation using the alkaline comet and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid (MTT) assays, respectively. Results suggest that the applied specific O₃ dose of 0.4 mg_O3/mg_DOC is a safe operation setup in terms of toxicologically relevant transformation products. In addition, no adverse effects on primary producers, as evidenced by algae growth inhibition tests, were detected. The monitored biofilm growth in the biological posttreatment exhibited a steady state after one month. Based on computational fluid dynamics (CFD) simulations and biomass, one might conclude that O₃ did not apparently enter biological posttreatment to a great extent and that hydraulic retention time in the O₃ reactor was sufficient. Our data demonstrate the effectiveness of a full-scale O₃ treatment in combination with a fluidized moving-bed reactor as biological posttreatment for the reduction of a majority of micropollutants without the release of relevant toxic transformation products as assessed by a chemical and toxicity-based approach.

A simple model for estimating the concentrations of natural estrogens in raw wastewater

This study provides a tool for predicting the concentrations of the natural estrogens (NEs) estrone, 17β-estradiol and estriol in raw wastewater (WW). Data characterizing the biochemical oxygen demand (BOD), NE concentrations, and discharges of raw sewage to wastewater treatment plants (WWTPs) were collected from various publications and used in the model formulation. A strong correlation was found between the log transformed BOD and the log transformed estrone load (r²=0.84, n=61), the log transformed 17β-estradiol load (r²=0.89, n=52) and the log transformed estriol load (r²=0.80, n=40). The models are reasonably accurate when compared to the measured concentrations and slightly better than previous modeling efforts. The relative amounts of data falling within ±50% error were 67% for estrone, 63% for 17β-estradiol, and 55% for estriol. Because the model was developed from a wide array of WWTPs from five continents, it is universal and can be used for projecting concentrations of NEs from a wide range of mixed domestic and industrial sources, but may be less precise when sources contain high levels of NEs or BOD (e.g., WW from dairy farms and food processing plants). The model is expected to improve our ability to predict the fate of NEs in WWTPs and in the receiving environment, which currently relies on estimating the concentrations of NEs in raw wastewater. Its application is especially valuable since direct measurement of NEs in raw WW is expensive and practically impossible in many developing countries due to the lack of expertise and funds.

Simultaneous determination of estrogenic odorant alkylphenols, chlorophenols, and their derivatives in water using online headspace solid phase microextraction coupled with gas chromatography-mass spectrometry

A simple online headspace solid-phase microextraction (HS-SPME) coupled with the gas chromatography-mass spectrometry (GC-MS) method was developed for simultaneous determination of trace amounts of nine estrogenic odorant alkylphenols and chlorophenols and their derivatives in water samples. The extraction conditions of HS-SPME were optimized including fiber selection, extraction temperature, extraction time, and salt concentration. Results showed that divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was the most appropriate one among the three selected commercial fibers, and the optimal extraction temperature, time, and salt concentration were 70 °C, 30 min, and 0.25 g/mL, respectively. The developed method was validated and showed good linearity (R (2) > 0.989), low limit of detection (LOD, 0.002-0.5 μg/L), and excellent recoveries (76-126 %) with low relative standard deviation (RSD, 0.7-12.9 %). The developed method was finally applied to two surface water samples and some of these target compounds were detected. All these detected compounds were below their odor thresholds, except for 2,4,6-TCAS and 2,4,6-TBAS wherein their concentrations were near their odor thresholds. However, in the two surface water samples, these detected compounds contributed to a certain amount of estrogenicity, which seemed to suggest that more attention should be paid to the issue of estrogenicity rather than to the odor problem.

Levels of six antibiotics used in China estimated by means of wastewater-based epidemiology

Due to lack of proper regulation, information about antibiotics consumption in many countries such as China is difficult to obtain. In this study, a simple method based on wastewater-based epidemiology was adopted to estimate their usage in four megacities of China. Six antibiotics (norfloxacin, ofloxacin, sulfamethoxazole, trimethoprim, erythromycin and roxithromycin), which are the most frequently consumed antibiotics in China, were selected as the targets. Based on our results, Chongqing had the largest total annual consumption of the selected six antibiotics among the four megacities, followed by Guangzhou, then Hong Kong, with Beijing having the least, with values of 4.4 g/y/P, 4.0 g/y/P, 1.6 g/y/P, and 1.3 g/y/P, respectively. Compared with the daily consumption per capita in Italy, the estimated consumption levels of the selected six antibiotics in four cities of China were 12-41 times those of Italy. Our results suggested that the consumption of antibiotics in China was excessive.

Estimated human excretion rates of natural estrogens calculated from their concentrations in raw municipal wastewater and its application

Natural estrogens are important endocrine disrupting compounds (EDCs), which may pose adverse effects on our environment. To avoid time-consuming sample preparation and chemical analysis, estimation of their concentrations in municipal wastewater based on their human urine/feces excretion rates has been generally adopted. However, the data of excretion rates available are very limited and show significant difference among countries. In the context of increasing reporting on the concentrations of natural estrogens in municipal wastewater around the world, this study presented a simple method to estimate their human excretion rates based on the concentrations of natural estrogens in raw sewage. The estimated human excretion rates of natural estrogens among ten countries were obtained, which totally covered over 33 million population. Among these, Brazilians had the largest excretion rates with estrone (E1) and 17β-estradiol (E2) as 236.9 and 60 μg/day/P, respectively, while Iran had the lowest value of 2 μg/day/P for E1 and 0.5 μg/day/P for E2. The average estimated human excretion rates of E1, E2, and estriol (E3) are 17.3, 6.4, and 39.7 μg/day/P, respectively. When the estimated human excretion rates obtained were applied for prediction, the predicted results showed better accuracies than those based on human urinary/feces excretion rates. The method in this study is simple, cost-effective and time-saving, which may be widely applied.

Removal of natural estrogens and their conjugates in municipal wastewater treatment plants: a critical review

This article reviews studies focusing on the removal performance of natural estrogens in municipal wastewater treatment plants (WWTPs). Key factors influencing removal include: sludge retention time (SRT), aeration, temperature, mixed liquor suspended solids (MLSS), and substrate concentration. Batch studies show that natural estrogens should biodegrade well; however, batch observations do not always agree with observations from full-scale municipal WWTPs. To explain this discrepancy, deconjugation kinetics of estrogen conjugates in lab-scale studies were examined and compared. Most estrogen conjugates with slow deconjugation rates are unlikely to be easily removed; others could be cleaved in WWTP settings. Nevertheless, some estrogens cleaved from their conjugates may be found in treated effluent, because deconjugation requires several hours or longer, and there is insufficient rest time for the biodegradation of the cleaved natural estrogens in the WWTP. Therefore, WWTP removals of natural estrogens are likely to be underestimated when estrogen conjugates are present in raw wastewater. This review suggests that biodeconjugation of estrogen conjugates should be enhanced to more effectively remove natural estrogens in WWTPs.