Catalytic wet-air oxidation (CWAO) of aqueous solutions of bisphenol A (BPA) was investigated in a trickle-bed reactor at temperatures up to 230 °C and oxygen partial pressure of 10.0 bar over TiO2 ...and Ru/TiO2 solids. It was observed that in the given range of operating conditions BPA undergoes both noncatalyzed and catalyzed oxidation routes. The employed Ru/TiO2 catalyst containing 3.0 wt % of metallic phase enabled complete removal of BPA and more than 96% of TOC removal at temperatures of 200 °C and above. No catalyst deactivation occurred that could be attributed to the dissolution of active ingredient material. At these conditions, no carbonaceous deposits were accumulated on the catalyst surface. The acute toxicity of end-product solutions to organisms from different taxonomic groups and estrogenicity determined by the genetically modified yeast, compared with those of the feed solutions, was significantly reduced by CWAO treatment over the Ru/TiO2 catalyst. For comparison, oxidative destruction of BPA was also investigated in this study by means of either photolytic or heterogeneous photocatalytic oxidation. A commercial TiO2 photocatalyst illuminated by UV light enabled complete removal of BPA; however, lower decrease of toxicity and estrogenicity in the treated solution was observed.
The presence of endocrine-disrupting compounds in wastewater, surface water, groundwater and even drinking water has become a major concern worldwide, since they negatively affect wildlife and ...humans. Therefore, these substances should be effectively removed from effluents before they are discharged into surface water to prevent pollution of groundwater, which can be a source of drinking water. Furthermore, an efficient control of endocrine-disrupting compounds in wastewater based on biological and analytical techniques is required. In this study, a yeast estrogen screen (YES) bioassay has been introduced and optimized with the aim to assess potential estrogenic activity of waters. First, assay duration, concentration of added substrate to the assay medium and wavelength used to measure the absorbance of the substrate were estimated. Several compounds, such as 17-β-estradiol, 17-α-ethinylestradiol, bisphenol A, nonylphenol, genisteine, hydrocortisone, dieldrin, atrazine, methoxychlor, testosterone and progesterone were used to verify its specificity and sensitivity. The optimized YES assay was sensitive and responded specifically to the selected estrogenic and nonestrogenic compounds in aqueous samples. Potential estrogenicity of influent and effluent samples of two wastewater treatment plants was assessed after the samples had been concentrated by solid-phase extraction (SPE) procedure using Oasis® HLB cartridges and methanol as eluting solvent. Up to 90 % of relative estrogenic activity was detected in concentrated samples of influents to wastewater treatment plants and estrogenic activity was still present in the concentrated effluent samples. We found that the introduced YES assay is a suitable screening tool for monitoring the potential estrogenicity of effluents that are discharged into surface water. Key words: endocrine-disrupting compounds, estrogenic activity, monitoring, solid-phase extraction, yeast estrogen screen assay, water
Commercial product Degussa TiO2 P25, sol-gel produced TiO
2
and TiO
2
modified by carbon nanotubes addition (5% of the TiO
2
mass) are tested as photocatalysts for the degradation of endocrine ...disrupting compound 17α-ethynylestradiol (1 µM aqueous solution). The molecular and crystal structure, phase composition, crystallite size, specific surface area, pore average diameter, their area and volume distribution, morphology, IR and UV/Vis spectra of the catalysts are characterized. HPLC is used for estrogen analysis. The sorption ability and photocatalytic activity (measured by degradation rate constant and percentage of the pollutant conversion) of the catalysts under UV (17 W, emission maximum at 254 nm) irradiation is determined. Full destruction of the pollutant is reached after 30 min irradiation in presence of Degussa P25. The performance of some of the catalysts is compared with literature data for their activity under 365 nm-illumination.
Estrogenic activity has been detected in aquatic ecosystems across the world. However, there is a lack of such data for Slovenian wastewaters and surface waters. The Slovenian monitoring program of ...effluents discharged into surface waters does not require that emissions of natural and synthetic estrogens into aquatic environments be assessed and controlled. In our study, we assessed the potential estrogenicity of wastewater samples from three wastewater treatment plants using a yeast estrogen screen assay (YES assay). Due to the high inhibition of yeast growth in samples obtained during our first sampling period, it was impossible to detect any estrogenic activity. An additional silica gel clean-up step reduced the toxicity of samples collected during our second sampling period; as a result, we were able to record up to 95% relative estrogenic activity inhibition. Deconjugation of the estrogens did not significantly influence our results. We detected estrogenic activity using a YES assay in almost all influent and effluent samples tested, which suggests that the wastewater treatment plants (WWTPs) examined do not effectively remove (xeno)estrogens from wastewaters. Our results suggest that a YES assay is an appropriate screening method for monitoring estrogenic activity in effluents. However, prediction of the potential impacts of wastewater (xeno)estrogens on aquatic organisms require additional in vitro and in vivo assays.
A bacterial model system (Pseudomonas putida DSM 50026) was used in this research to assess toxicity of the environmentally relevant concentrations of mercury species (MeHg and Hg(II)) that represent ...important pollutants of aquatic ecosystems at sites of industrial or mining activities. In addition to direct monitoring of bacterial growth, we also analyzed fatty acid profiles of exposed and non-exposed cultures to determine possible toxic effects manifested on membrane level. The results showed that exposure of P. putida to Hg(II) in concentrations of 0.2–200 µg/L did not have any significant effects on growth nor fatty acid composition of exposed bacterial culture. On the other hand, when bacteria were exposed to up to 1600-times lower concentrations of MeHg (0.12–12.5 µg/L), growth inhibition as well as significant changes in fatty acid composition were detected. Observed adaptive membrane changes due to MeHg exposure were similar to those associated with responses to organic solvents and some other membrane-disrupting compounds.
The ubiquitous presence of endocrine-disrupting compounds (EDCs) in the environment is mainly the consequence of their incomplete removal from biological wastewater treatment plants. One of the ...promising options for EDC removal is catalytic wet-air oxidation (CWAO), where pollutants are oxidized by activated O2 species in the presence of a solid catalyst. 17β-estradiol (E2) was used in CWAO experiments conducted in a trickle-bed reactor up to 230°C over TiO2 and Ru/TiO2 solids. In the given range of operating conditions, E2 undergoes noncatalytic and catalytic oxidation routes. The employed Ru(3.0wt.%)/TiO2 catalyst enabled complete and long lasting efficiency of E2 degradation as well as removal of estrogenicity from the feed solution. No deactivation occurred and no carbonaceous deposits were accumulated on the catalyst surface.
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► Treatment of aqueous 17β-estradiol (E2) solution by catalytic wet-air oxidation. ► The use of catalysts enables complete removal of E2 and estrogenicity. ► Long-term stability of Ru/TiO2 in catalytic wet-air oxidation process was observed. ► No reaction intermediates that exhibit estrogenic effects were formed.
For the first time, data on the effect of TiO
2
modification by N-doping or by carbon nanotubes on the photocatalytic destruction of endocrine disrupting compounds 17α-ethynylestradiol (EE2) and ...17β-estradiol (E2) in aqueous solutions are reported. A possibility to accomplish photocatalytic process under halogen lamp irradiation is shown. The catalyst is prepared by a sol–gel method. During the synthesis process, it is modified by N-doping (1.8 % nitrogen) or by carbon nanotube addition (5 % of the TiO
2
mass). X-ray diffractometry, SEM, TEM, N
2
adsorption–desorption, X-ray photoelectron and UV–Vis diffuse reflectance spectroscopy are applied for characterization. The crystal structure, phase composition, crystallites size, specific surface area, pores average diameter, pore area and volume distribution, morphology, UV–Vis and X-ray photoelectron spectra of the materials are reported and discussed. An HPLC technique is used for estrogen analysis. The sorption ability and photocatalytic activity (measured by degradation rate constant and percentage of the pollutant conversion) of the catalysts under UV (150 W, emission maximum at 365 nm) or 150 W halogen lamp illumination are determined. Full destruction of E2 and >99.7 % of EE2 is reached after 2 h irradiation with halogen lamp.
Estrogen 17β-estradiol (E2), produced by human body and excreted into municipal wastewaters, belongs to the group of endocrine disrupting compounds that are resistant to biological degradation. The ...aim of this study was to assess the efficiency of E2 removal from aqueous solutions by means of catalytic wet-air oxidation (CWAO) and photolytic/photocatalytic oxidation. CWAO experiments were conducted in a trickle-bed reactor at temperatures up to 230 °C and oxygen partial pressure of 10 bar over TiO2 and Ru/TiO2 solids. Photolytic/photocatalytic oxidation was carried out in a batch slurry reactor employing a TiO2 P-25 (Degussa) catalyst under visible or UV light. HPLC analysis and yeast estrogen screen assay were used to evaluate the removal of E2 and estrogenicity of treated samples. The latter was completely removed during photolytic/photocatalytic oxidation under UV (365 nm) light and photocatalytic oxidation under visible light. In CWAO experiments, complete removal of both E2 and estrogenicity from the feed solution were noticed in the presence of TiO2 and Ru/TiO2 catalysts.
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.
A bacterial model system (Pseudomonas putida DSM 50026) was used in this research to assess potential effect of five selected chemically diverse environmental pollutants on cell membranes. Long chain ...fatty acid profiles of cultures exposed to environmentally relevant concentrations of atrazine (ATR), metolachlor (MET), pentachlorobiphenyl (PCB), hexachlorobenzene (HCB) and fluoranthene (FL), were analyzed and compared to non-exposed cultures. To assess sensitivity of membrane-based responses, the impact of each toxicant on culture growth was also followed spectrophotometrically. Results revealed changes in fatty acid profiles when cells were exposed to PCB, HCB and FL in concentrations below the inhibitory levels. Moreover, the observed membrane responses were similar to the ones previously associated with adaptation to some membrane-active compounds. On the other hand, exposure of cells to any of the two herbicides, ATR or MET, did not induce any significant changes in fatty acid profiles. However, when combined with a commonly used fertilizer compound, NH4NO3 growth impairment was observed. Synergistic effect of the two herbicides with NH4NO3 might be a consequence of changes in fatty acid profile increasing membrane fluidity, likely induced by NH4+ ions.
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