EE2 Removal Research Articles

Adsorption of bisphenol A and 17α-ethinyl estradiol on single walled carbon nanotubes from seawater and brackish water

Recent studies have shown the presence of endocrine disrupting compounds (EDCs) in seawater and brackish water, which could potentially complicate various seawater desalination treatment processes. In this study, the adsorption of bisphenol A (BPA) and 17α-ethinyl estradiol (EE2) by single walled carbon nanotubes (SWCNTs) was investigated. Solutions of artificial seawater, brackish water, and a combination of these two waters were prepared, in accordance with previously published composition data. Overall, the removal efficiency for EE2 (95–98%) was higher than BPA (75–80%), possibly because of its higher log KOW value. The adsorptive capacity of the SWCNTs remained relatively constant for the artificial source waters used in this study, suggesting that the changes in the composition of the water did not affect the overall adsorption of the EDCs. Adjusting the pH of the solutions from 3.5 to 11 showed a 22–26% decrease in the adsorption of BPA, whereas no notable changes were found in the adsorption of EE2. Changes in the ionic strength of the solutions by increasing the concentrations of Na+ and Ca2+ did not significantly affect the adsorption of BPA or EE2. The concentration of dissolved organic carbon (DOC), represented in this study by humic acid, had noticeable effects on the adsorption of BPA and EE2. As the concentration of DOC increased, the removal of BPA and EE2 decreased by 5–15%, which could possibly be explained by competitive adsorption between the EDCs and humic acid. With increasing concentrations of SWCNTs, adsorption of DOC occurred with removal efficiencies of up to 95%. Hydrophobic interactions and π–π electron donor–acceptor (EDA) interactions among the EDCs, the DOC, and the SWCNTs have been hypothesized as the potential adsorption mechanisms for BPA and EE2.

Removal of 17α-Ethinylestradiol by Biogenic Manganese Oxides Produced by the Pseudomonas putida strain MnB1

Synthetic and persistent endocrine disrupting chemicals (EDCs) such as 17α-ethinylestradiol (EE2) have been frequently detected in the effluent of wastewater treatment plants and induce hazards to humans and wildlife. In this study, biogenic Mn oxides were tested for the removal of EE2, and factors affecting the reaction were also investigated. The biogenic Mn oxides produced by Pseudomonas putida strain MnB1 were nano-sized and poorly crystallized particles. A concentration of 7.9 mg l−1 biogenic Mn oxides showed 87% EE2 (1 mg l−1) removal efficiency in 2 h, which confirms the excellent potential of biogenic Mn oxides for removal of estrogens. EE2 removal was enhanced at high Mn oxide doses and at low pH. Co-existing heavy metals significantly inhibit EE2 removal, due to their competition for the reactive sites of biogenic Mn oxides. Humic acid (HA) also obstructed EE2 removal, but the adverse effect was alleviated as HA concentration increased, possibly due to the formation of soluble complexes with the released Mn2+, of which adsorption onto Mn oxides reduces surface reactive sites.

BDD anodic oxidation as tertiary wastewater treatment for the removal of emerging micro‐pollutants, pathogens and organic matter

AbstractThis work reports for the first time the removal of 17α‐ethynylestradiol (EE2), a synthetic estrogen hormone, from secondary treated effluents by electrochemical oxidation. Experiments were conducted in a single compartment reactor comprising a boron‐doped diamond (BDD) anode and a zirconium cathode. EE2, in the range 100–800 µg L−1, was spiked in the post‐chlorination effluent of a municipal treatment plant and oxidized at 0.9–2.6 mA cm−2 current density. Complete degradation of 100 µg L−1 EE2 was achieved in 7 min at 2.1 mA cm−2 and inherent conditions, while the addition of 0.1 mol L−1 NaCl achieved removal in just a few seconds. The process was then tested in the pre‐chlorination effluent at 2.1 mA cm−2 and inherent conditions; complete E. coli killing and EE2 removal occurred in just 1.5 and 3.5 min, respectively, while overall estrogenicity (assessed by the YES assay) and residual organic matter (in terms of chemical oxygen demand (COD)) decreased by 50% and 85% after 30 min, respectively. These results clearly show the potential of BBD electrochemical oxidation to serve as an efficient tertiary wastewater treatment. Copyright © 2011 Society of Chemical Industry

Removal of bisphenol A and 17α-ethinyl estradiol from landfill leachate using single-walled carbon nanotubes

In this study, the adsorption of bisphenol A (BPA) and 17α-ethinyl estradiol (EE2) from landfill leachate onto single-walled carbon nanotubes (SWCNTs) was investigated. Different leachate solutions were prepared by altering the pH, ionic strength, and dissolved organic carbon (DOC) in the solutions to mimic the varying water conditions that occur in leachate during the various stages of waste decomposition. The youngest and oldest leachate solutions contained varying DOC and background chemistry and were represented by leachate Type A (pH = 5.0; DOC = 2500 mg/L; conductivity = 12,500 μS/cm; [Ca 2+] = 1200 mg/L; [Mg 2+] = 470 mg/L) and Type E (pH = 7.5; DOC = 250 mg/L; conductivity = 3250 μS/cm; [Ca 2+] = 60 mg/L; [Mg 2+] = 180 mg/L). These solutions were subsequently combined in different ratios to produce intermediate solutions, labeled B–D, to replicate time-dependent changes in leachate composition. Overall, a larger fraction of EE2 was removed as compared to BPA, consistent with its higher log K OW value. The total removal of BPA and EE2 decreased in older leachate solutions, with the adsorptive capacity of SWCNTs decreasing in the order of leachate Type A > Type B > Type C > Type D > Type E. An increase in the pH from 3.5 to 11 decreased the adsorption of BPA by 22% in young leachate and by 10% in old leachate. The changes in pH did not affect the adsorption of EE2 in the young leachate, but did reduce adsorption by 32% in the old leachate. Adjusting the ionic strength using Na + did not significantly impact adsorption, while increasing the concentration of Ca 2+ resulted in a 12% increase in the adsorption of BPA and a 19% increase in the adsorption of EE2. DOC was revealed to be the most influential parameter in this study. In the presence of hydrophilic DOC, represented by glucose in this study, adsorption of the endocrine disrupting compounds (EDCs) onto the SWCNTs was not affected. In the absence of SWCNTs, hydrophobic DOC (i.e., humic acid) adsorbed 15–20% of BPA and EE2. However, when the humic acid and SWCNTs were both present, the overall adsorptive capacity of the SWCNTs was reduced. Hydrophobic (π-π electron donor-acceptor) interactions between the EDCs and the constituents in the leachate, as well as interactions between the SWCNTs and the EDCs, are proposed as potential adsorption mechanisms for BPA and EE2 onto SWCNTs.

Comparison of Fenton's oxidation and ozonation for removal of estrogens

This study compares efficiency of Fenton's oxidation and ozonation of 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) as two possible processes for removal of estrogens from aqueous solutions. The effectiveness of Fenton's oxidative removal was studied at different ratios of reagents Fe2+:H2O2 (1:0.5; 1:10; 1:20; 1:33), where with some molar ratios up to 100% removal of E2 and EE2 was achieved in the first few minutes of reaction. The best molar ratio for E2 (17beta-estradiol) removal was 1:33, while in the case of EE2 the most efficient one was 1:20 ratio. Ozonation was much faster, because complete removal of estrogens was achieved in 30 seconds (pH approximately eaqual 6), but the time of ozonation was extended up to 60 minutes trying to decompose formed by-products, expressing estrogenic activity, detected by YES (Yeast Estrogen Screening) assay. The obtained results showed that the removal efficiency of estrogens from waters should be assessed by a combination of chemical analyses and bioassay.

Endocrine disruptive synthetic estrogen (17α-ethynylestradiol) removal from aqueous phase through batch and column sorption studies: Mechanistic and kinetic analysis

Global concern about the persistence of endocrine disrupting chemicals (EDC) in the freshwater environment is more evident due to their possible disruptive effects. Even at nanogram levels these compounds increase the risk of cancer, decrease egg and sperm production, reduce gamete quality and tend complete feminization of the male fish. The present study demonstrated the potential of activated charcoal as adsorbent in removing synthetic estrogen 17α-ethynylestradiol (EE2) from aqueous phase by sorption process employing both agitated batch and column adsorption experiments. Batch sorption studies showed good removal of EE2 and dependent on the concentration loaded. Equilibrium data of EE2-charcoal sorption system showed a reasonably good fit with pseudo first-order kinetic plot. Intra-particle diffusion plot indicated the complex nature of EE2-charcoal sorption system involving both boundary layer and intra-particle diffusions. Experimental data confirmed to linear Langmuir's isotherm model. Highest EE2 sorption capacity of activated charcoal was observed at neutral conditions. Fixed bed column studies were performed with EE2 spiked untreated domestic sewage. Based on the data derived by fixed bed column studies, rapid small-scale column test (RSSCT) methodology was used to design full-scale GAC system. Total EE2 concentration was quantitatively estimated by direct competitive immuno-enzymatic colorimetric method.

Elucidating the Relative Roles of Ammonia Oxidizing and Heterotrophic Bacteria during the Biotransformation of 17α-Ethinylestradiol and Trimethoprim

The biological fate of 17α-ethinylestradiol (EE2; 500 ng/L to 1 mg/L) and trimethoprim (TMP; 1 μg/L to 1 mg/L) was evaluated with flow through reactors containing an ammonia oxidizing bacterial (AOB) culture, two enriched heterotrophic cultures devoid of nitrifier activity, and nitrifying activated sludge (NAS) cultures. AOBs biotransformed EE2 but not TMP, whereas heterotrophs mineralized EE2, biotransformed TMP, and mineralized EE2-derived metabolites generated by AOBs. Kinetic bioassays showed that AOBs biotransformed EE2 five times faster than heterotrophs. The basal expression of heterotrophic dioxygenase enzymes was sufficient to achieve the high degree of transformation observed at EE2 and TMP concentrations ≤ 1 mg/L, and enhanced enzyme expression was not necessary. The importance of AOBs in removing EE2 and TMP was evaluated further by performing NAS experiments at lower feed concentrations (500-1000 ng/L). EE2 removal slowed markedly after AOBs were inhibited, while TMP removal was not affected by AOB inhibition. Two key EE2 metabolites formed by AOB and heterotrophic laboratory-scale chemostats were also found in independent laboratory-scale mixed culture bioreactors; one of these, sulfo-EE2, was largely resistant to further biodegradation. AOBs and heterotrophs may cooperatively enhance the reliability of treatment systems where efficient removal of EE2 is desired.

Removal and fate of estrogens in an anaerobic-anoxic-oxic activated sludge system

Laboratory-scale experiments were conducted to investigate the removal and fate of estrogens 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in an anaerobic-anoxic-oxic (AAO) activated sludge system. Estrogen concentrations in the aqueous and solid phases in each reactor of AAO system were analyzed separately. E2 was not detected in the final effluent. The anaerobic, anoxic and oxic reactors accounted for 71%, 7% and 22% of the overall E2 removal, respectively. The overall EE2 removal efficiency was about 80%, and the anaerobic, anoxic and oxic reactors were responsible for 44%, 8% and 48% of the overall EE2 removal, respectively. In anaerobic unit, sorption was the dominant mechanism for the removal of E2 and EE2. While E2 was degraded in all the three units of the AAO system, EE2 was only degraded in the anoxic and aerobic units. Biodegradation is important for the fate of E2 compared to sorption. Of the total influent E2 in the AAO system, 99.99% was biodegraded and 0.01% remained in the waste sludge. Nevertheless, both sorption and biodegradation play important roles in the removal of EE2. Of the total influent EE2, 79.1% was degraded by activated sludge, 19.9% was discharged in the effluent and 1% remained in the waste sludge.

Exploring 17α-ethinylestradiol removal, mineralization, and bioincorporation in engineered bioreactors

This research investigated removal, mineralization, and bioincorporation of 17α-ethinylestradiol (EE2) in membrane bioreactors and conventional bioreactors. When the influent EE2 concentration was >50 μg/L, the membrane bioreactor (MBR) biomass removed more EE2 than conventional bioreactor (CBR) biomass in continuous tests, likely because the sorption partitioning coefficients are higher for MBR biomass. Microautoradiography was carried out to investigate the distribution of EE2 within the aggregates retrieved from the bioreactors, and the results revealed concentration gradients present within the floc. Experiments using radiolabeled 14C-EE2 experiments (done with 24.5 μg/L EE2) showed that EE2 removal rates and the amount of EE2 mineralized were similar in MBRs and CBRs. Direct measurements and bioenergetic estimates suggest that EE2-related carbon is probably incorporated into active biomass, despite the fact that EE2 was added at a concentration that was much lower than that of the primary growth substrates.

Biodegradation of oestrogens in nitrifying activated sludge

The degradation of 17β‐oestradiol (E2) and 17α‐ethinyloestradiol (EE2) was investigated in an aerobic activated sludge system fed with synthetic wastewater. The effect of different solid residence times (SRTs) and nitrification inhibitors, such as allylthiourea (ATU), was studied in order to assess which group of microorganisms plays a significant role in the degradation of oestrogens. E2 was effectively converted into oestrone (E1) under all the conditions encountered in the nitrifying activated sludge system. The degradation of E2 obeyed first‐order reaction kinetics; with an increase in SRT from 12 to 20 days, the degradation rate constant, k, decreased from 2.3 h−1 to 0.47 h−1. The removal of EE2 did not change significantly with the addition of ATU and at different SRTs. Only about 20% of EE2 was removed from the system, which demonstrated that EE2 was more recalcitrant than natural oestrogens. The results are supported by other recent studies, which suggest that co‐metabolic degradation of EE2 and E2 by ammonia‐oxidizing bacteria is not an important removal mechanism. The primary mechanism for E2 and EE2 degradation in activated sludge is most probably the activity of heterotrophic bacteria.

Membrane bioreactors for 17α-ethinylestradiol removal

The synthetic hormone 17α-ethinylestradiol (EE2) is an endocrine disrupter of great concern with insufficient removal in wastewater treatment plants (WWTP) and subsequent impacts on the aquatic environment. In this paper, membrane bioreactor (MBR) technology was compared with conventional activated sludge (CAS) systems. Contrary to previous studies on MBRs, continuous purification was combined with the determination of sorption and biodegradation parameters. In addition, EE2 removal was studied in two different MBR configurations. Continuous purification with AS acclimated in the MBR (MLVSS of 9 g L −1 and a 50-d SRT) resulted in the stabilization of the EE2 removal at a plateau of 65% (initial load of 1.8 mg EE2 g MLVSS −1 d −1). In contrast, CAS resulted in EE2 accumulation in the permeate. During batch kinetics, CAS was shown to remove EE2 only through sorption (87% removal of EE2) whereas AS acclimated to the MBR process developed biodegradation abilities towards the synthetic hormone (7% removal of EE2). Therefore, the membrane process combined with AS was shown to be essential to improve EE2 removal (with the autotrophic activity as the key factor). In addition, either the external or the external-immersed configuration can be applied, due to similar performance with respect to EE2 removal.

Effects of powdered activated carbon dosing on sludge characteristics and estrogen removal in membrane bioreactors

Sludge characteristics associated with filterability as well as the removal of a natural estrogen 17beta-estradiol (E2) and a synthetic estrogen 17alpha-ethyinylestradiol (EE2) were investigated in submerged membrane bioreactors (MBR) with and without the addition of powdered activated carbon (PAC) under the same experimental conditions. Positive impacts of PAC dosing on membrane fouling and the removal of E2 and EE2 were demonstrated over a six months stable operational period. Experimental results showed that PAC dosing resulted in lower concentrations of soluble extracellular polymeric substances (EPS) and colloidal total organic carbon (TOC) in the PAC-MBR sludge. The average soluble EPS and colloidal TOC concentrations in the PAC-MBR sludge was 60.1% and 61.8% lower than the control MBR sludge, respectively. Regardless of PAC dosing, concentrations of colloidal TOC were strongly related to concentrations of soluble EPS and soluble carbohydrates in the sludge. In addition, the mean flocs size of the sludge with PAC dosing was shifted from 49.4 microm to 60.3 microm. PAC dosing in the MBR increased the removal rates of E2 and EE2 by 3.4% and 15.8%, respectively.

Kinetic parameters for 17α-ethinylestradiol removal by nitrifying activated sludge developed in a membrane bioreactor

The synthetic hormone 17α-ethinylestradiol (EE2) is primarily removed in wastewater treatment plants (WWTPs) by sorption, and nitrifying biomass has been shown to be responsible for EE2 biodegradation. Membrane bioreactor (MBR) technology was chosen to develop a community of autotrophic, nitrifying micro-organisms and determine kinetic parameters for EE2 biodegradation. Biological inhibition by azide was applied to differentiate sorption from biodegradation. Activated sludge (AS) was acclimated in the MBR to a substrate specific to autotrophic biomass and resulted in an increase in nitrifying activity. Acclimated AS was used to successfully biodegrade EE2 (11% increase in EE2 removal), and the overall removal of EE2 was determined to be 99% (sorption + biodegradation). AS used directly from a WWTP without acclimation removed EE2 only through sorption (88% removal of EE2). Therefore, higher nitrifying activity developed by acclimating AS allowed almost complete removal of EE2.

Removal of Pharmaceutical and Personal Care Products (PPCPs) under nitrifying and denitrifying conditions

The contribution of volatilization, sorption and transformation to the removal of 16 Pharmaceutical and Personal Care Products (PPCPs) in two lab-scale conventional activated sludge reactors, working under nitrifying (aerobic) and denitrifying (anoxic) conditions for more than 1.5 years, have been assessed. Pseudo-first order biological degradation rate constants ( k biol) were calculated for the selected compounds in both reactors. Faster degradation kinetics were measured in the nitrifying reactor compared to the denitrifying system for the majority of PPCPs. Compounds could be classified according to their k biol into very highly ( k biol > 5 L g SS −1 d −1), highly (1 < k biol < 5 L g SS −1 d −1), moderately (0.5 < k biol < 1 L g SS −1 d −1) and hardly ( k biol < 0.5 L g SS −1 d −1) biodegradable. Results indicated that fluoxetine (FLX), natural estrogens (E1 + E2) and musk fragrances (HHCB, AHTN and ADBI) were transformed to a large extent under aerobic (>75%) and anoxic (>65%) conditions, whereas naproxen (NPX), ethinylestradiol (EE2), roxithromycin (ROX) and erythromycin (ERY) were only significantly transformed in the aerobic reactor (>80%). The anti-depressant citalopram (CTL) was moderately biotransformed under both, aerobic and anoxic conditions (>60% and >40%, respectively). Some compounds, as carbamazepine (CBZ), diazepam (DZP), sulfamethoxazole (SMX) and trimethoprim (TMP), manifested high resistance to biological transformation. Solids Retention Time (SRT aerobic >50 d and <50 d; SRT anoxic >20 d and <20 d) had a slightly positive effect on the removal of FLX, NPX, CTL, EE2 and natural estrogens (increase in removal efficiencies <10%). Removal of diclofenac (DCF) in the aerobic reactor was positively affected by the development of nitrifying biomass and increased from 0% up to 74%. Similarly, efficient anoxic transformation of ibuprofen (75%) was observed after an adaptation period of 340 d. Temperature (16–26 °C) only had a slight effect on the removal of CTL which increased in 4%.

Effects of floc aluminum on activated sludge characteristics and removal of 17-α-ethinylestradiol in wastewater systems

The effects of floc aluminum (Al) on activated sludge performance and 17-α-ethinylestradiol (EE2) removal were studied using bench-scale activated sludge systems. The results showed that higher Al-fed activated sludge led to better settling, dewatering, and effluent quality with better EE2 removal. EE2 concentrations in the effluent revealed correlations with effluent suspended solids and large particulate/colloidal effluent biopolymer (protein + polysaccharide). Furthermore, a significant correlation existed between effluent proteins and EE2 for all size fractions, indicating that hydrophobic proteinaceous colloids provide binding sites for EE2 and washout together into the effluent. These results suggest that aluminum plays a crucial role in bioflocculation of activated sludge and the efficacy of flocculation influences the removal of endocrine disrupting compounds (EDCs) from wastewater treatment systems.

Nitrate‐dependent degradation of 17α‐ethinylestradiol by acclimated activated sludge under anaerobic conditions

AbstractBACKGROUND: The synthetic estrogen 17α‐ethinylestradiol (EE2) is of great environmental concern. Batch experiments were conducted to investigate the removal of EE2 by activated sludge under anaerobic conditions with or without nitrate. The effect of temperature on EE2 removal was also estimated.RESULTS: No biodegradation of EE2 was observed in the absence of nitrate; owing to sorption onto the activated sludge, the overall removal EE2 rate was 62%; the sorption was fitted to both Freundlich and linear sorption models; the sorption rate decreased with the increase temperature. In the presence of nitrate, the overall removal rate of EE2 was greater than 97% after 72 h, mostly from biodegradation (95%); the biodegradation could be described by first‐order reaction kinetics with average rate constant of 0.0344 h−1; increasing temperature enhanced the rate constant and the removal rate could be as high as 96–98% in the temperature range 10–30 °C.CONCLUSION: EE2 was removed by activated sludge under anaerobic conditions. In the absence of nitrate, the removal of EE2 was a result of sorption onto activated sludge. In the presence of nitrate, biodegradation was the dominant process for EE2 removal. Higher temperature improves biodegradation rate, but reduces the sorption of EE2 onto activated sludge. Copyright © 2009 Society of Chemical Industry

Removal of arsenate and 17α-ethinyl estradiol (EE2) by iron (hydr)oxide modified activated carbon fibers

Activated carbon fibers (ACF) were modified with iron (hydr)oxide and studied to determine their suitability to remove arsenate and 17α -ethinyl estradiol (EE2) from water. Two synthesis methods, one involving aqueous KMnO4 pretreatment followed by Fe(II) treatment, and the other involving reaction with Fe(III) in an organic solvent followed by NaOH treatment, were used to produce modified ACF media containing 5.9% and 8.4% iron by dry weight, respectively. Scanning electron microscopy (SEM) and Electron dispersion X-ray (EDX) techniques indicated slightly higher iron content near the outer edges of the fibers. Pseudo-equilibrium batch test experimental data at pH = 7.0 ± 0.1 in 5 mM NaHCO3 buffered ultrapure water containing ∼ 100 μ g(As)/L and ∼ 500 μ gEE2/L were fitted with the Freundlich isotherm model (q = K × C E 1/n ). The adsorption capacity parameters (K) were ∼ 2586 (μ gAs/gFe)(L/μ gAs)1/n and ∼ 425 (μ gAs/gFe)(L/μ gAs)1/n ), respectively, for the KMnO4/Fe(II) and Fe(III)/NaOH treated media. The KMnO4/Fe(II) media exhibited a lower adsorption capacity at 99% EE2 removal than did the Fe(III)/NaOH treated media (1.3 mgEE2/g -dry -media vs. 1.8 mgEE2/g -dry -media). The arsenate adsorption intensity parameters (1/n) for both modified ACF media were < 0.29, implying very favorable adsorption, which suggests that this type of media may be suitable for single point -of -use applications in which arsenic and organic co-contaminants require simultaneous removal and the depth of the packed bed is the key factor.

Biological removal of 17α-ethinylestradiol by a nitrifier enrichment culture in a membrane bioreactor

Increasing concern about the fate of 17α-ethinylestradiol (EE2) in the environment stimulates the search for alternative methods for wastewater treatment plant (WWTP) effluent polishing. The aim of this study was to establish an innovative and effective biological removal technique for EE2 by means of a nitrifier enrichment culture (NEC) applied in a membrane bioreactor (MBR). In batch incubation tests, the microbial consortium was able to remove EE2 from both a synthetic minimal medium and WWTP effluent. A maximum EE2 removal rate of 9.0 μg EE2 g −1 biomass-VSS h −1 was achieved (>94% removal efficiency). Incubation of the heterotrophic bacteria isolated from the NEC did not result in a significant EE2 removal, indicating the importance of nitrification as driving force in the mechanism. Application of the NEC in a MBR to treat a synthetic influent with an EE2 concentration of 83 ng EE2 L −1 resulted in a removal efficiency of 99% (loading rates up to 208 ng EE2 L −1 d −1; membrane flux rate: 6.9 L m −2 h −1). Simultaneously, complete nitrification was achieved at an optimal ammonium influent concentration of 1.0 mg NH 4 +-N L −1. This minimal NH 4 +-N input is very advantageous for effluent polishing since the concomitant effluent nitrate concentrations will be low as well and it offers opportunities for the nitrifying MBR as a promising add-on technology for WWTP effluent polishing.

Removal and degradation characteristics of natural and synthetic estrogens by activated sludge in batch experiments

The removal and degradation characteristics of natural and synthetic estrogens by activated sludge were investigated by a series of batch experiments using the activated sludge samples of four actual wastewater treatment plants and synthetic wastewater spiked with estrogen. The rapid removal and degradation of 17β-estradiol (E2) and estrone (E1) were observed by the activated sludge samples of the oxidation ditch process which operated at higher solids retention time (SRT). On the other hand, E1 tended to remain both in the water phase and the sludge phase in the activated sludge samples of the conventional activated sludge process which operated at lower SRT. The anoxic condition was considered to be not favorable to the effective removal of estrogens as compared with the aerobic condition. The removal and degradation of EE2 showed the lag phase, which neither E2 nor E1 showed, but EE2 was finally removed and degraded completely after 24 h. The removal of estrogens in the water phase did not follow the first-order-rate reaction because a large part of the spiked estrogen was immediately removed from the water phase to the sludge phase by adsorption.

Influence of manganese and ammonium oxidation on the removal of 17α-ethinylestradiol (EE2)

Flow-through reactors with manganese oxides were examined for their capacity to remove 17α-ethinylestradiol (EE2) at μg L −1 and ng L −1 range from synthetic wastewater treatment plant (WWTP) effluent. The mineral MnO 2 reactors removed 93% at a volumetric loading rate ( B V) of 5 μg EE2 L −1 d −1 and from a B V of 40 μg EE2 L −1 d −1 on, these reactors showed 75% EE2 removal. With the biologically produced manganese oxides, only 57% EE2 was removed at 40 μg EE2 L −1 d −1. EE2 removal in the ng L −1 range was 84%. The ammonium present in the influent (10 mg N L −1) was nitrified and ammonia-oxidizing bacteria (AOB) were found to be of prime importance for the degradation of EE2. Remarkably, EE2 removal by AOB continued for a period of 4 months after depleting NH 4 + in the influent. EE2 removal by manganese-oxidizing bacteria was inhibited by NH 4 +. These results indicate that the metabolic properties of nitrifiers can be employed to polish water containing EE2 based estrogenic activity.