Fate of endocrine disruptor compounds in an anaerobic membrane bioreactor (AnMBR) coupled to an activated sludge reactor

[EN] The occurrence and fate of three groups of micropollutants - alkylphenols, pentachlorophenol and hormones - were studied in a pilot plant consisting of an anaerobic membrane bioreactor (AnMBR) coupled to an activated sludge reactor (University of Cape Town configuration - UCT). Under anaerobic conditions, the octylphenol and technical-nonylphenol soluble concentrations increased producing negative degradation ratios (i.e., -175 and -118%, respectively). However, high 4-n-nonylphenol and bisphenol-A degradation ratios (92 and 59% for 4-n-nonylphenol and bisphenol-A, respectively) as well as complete pentachlorophenol, estrone, 17 beta-estradiol and 17 alpha-ethinylestradiol removal were observed. Under aerobic conditions (UCT), octylphenol, technical-nonylphenol, 4-n-nonylphenol and bisphenol-A degradation ratios were higher than 84%. The AnMBR thus removes a high proportion of 4-n-nonylphenol, pentachlorophenol, estrone, 17 beta-estradiol and 17 alpha-ethinylestradiol, but requires a later post-treatment process (such as UCT) to improve bisphenol-A, octylphenol and technical-nonylphenol degradation ratios. The overall AnMBR-UCT degradation ratios were 48% and 70% for octylphenol and technical-nonylphenol, respectively, and higher than 97% for 4-n-nonylphenol and bisphenol-A. The AnMBR produced a higher micropollutant accumulation in the sludge than the UCT: removal by adsorption in the AnMBR process was between 0.5 and 10%, and less than 0.5% in the UCT process. The combination of AnMBR and UCT technologies produces an effluent stream with low concentrations of micropollutants.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO, CTM2011-28595-C02-01 and CTM2011-28595-C02-02) and the European Regional Development Fund (ERDF).Abargues Llamas, MR.; Ferrer, J.; Bouzas Blanco, A.; Seco Torrecillas, A. (2018). Fate of endocrine disruptor compounds in an anaerobic membrane bioreactor (AnMBR) coupled to an activated sludge reactor. Environmental Science: Water Research & Technology (Online). 4(2):226-233. https://doi.org/10.1039/c7ew00382jS2262334

Structural features of alkylphenolic chemicals associated with estrogenic activity

The ability of certain man-made chemicals to mimic the effects of natural steroid hormones and their potential to disrupt the delicate balance of the endocrine system in animals are of increasing concern. The growing list of reported hormone-mimics includes the alkylphenolic (AP) compounds, a small number of which have been reported to be weakly estrogenic. In their most basic form, APs are composed of an alkyl group, which can vary in size, branching, and position, joined to a phenolic ring. The aim of this project was to identify the important structural features responsible for the estrogenic activity of AP chemicals. This was achieved by incubating APs with different structural features in a medium containing a previously described estrogen-inducible strain of yeast (Saccharomyces cerevisiae) expressing the human estrogen receptor and comparing their activity spectrophotometrically by the resulting color change of the medium. The results were compared to the effects of the main natural estrogen 17-estradiol. The data indicate that both the position (para > meta > ortho) and branching (tertiary > secondary = normal) of the alkyl group affect estrogenicity. Optimal estrogenic activity requires a single tertiary branched alkyl group composed of between 6 and 8 carbons located at the para position on an otherwise unhindered phenol ring. The results are discussed in relation to the purity and composition of the chemicals tested

Occurrence and fate of organic contaminants in wastes

This thesis deals with the determination of organic contaminants in wastes and is part of the multidisciplinary faculty programme 'Biological waste in circulation between urban and rural areas - biology and flow of energy and material' which started at SLU in 1994. To ensure long-term sustainability of food production it is important to recycle resources such as the nutrients and organic material in organic waste. The biodegradable fraction of source separated household waste is attractive as raw material for composting and anaerobic digestion, because the products can be used in agriculture and horticulture. Quality is an important aspect on compost and anaerobically digested organic household waste, and it is important to ensure that the products are not contaminated. As the available information on organic contaminants in the biodegradable fraction of household waste and the products thereof is limited, an important goal with this work was to increase the knowledge of organic contaminants in these material as a foundation for future studies to reduce the environmental risk from these materials. Chlorinated paraffins (CPs) were found in fresh household waste. CPs are a complex mixture of chlorinated alkanes with varying (10-30) carbon chain lengts and varying (30- 70%) unspecific chlorination. The high numbers of isomers and homologues complicates the determination of CPs. We found that multivariate analysis can be used to interpret chromatographic data of CPs and this was used to characterise the CP contamination of houshold waste. It is presently impossible to pin-point the source of CP contamination using the data available, but most probably the contamination occurs during the collection of the waste. To further improve the determination of CPs an extraction method using high diffusion liquids, pressurised liquid extraction (PLE) was developed. PLE was shown to be a suitable technique for extracting CPs from complex matrices such as fresh household waste. A source close to the collection chain is also indicated for polychlorinated biphenyls (PCB). The PCB-profile found in the fresh household waste resembles that of a low chlorinated technical product. The PCB-profile expected in this type of material would originate from waste of animal origin in which the low chlorinated congeners have been degraded and the more highly chlorinated and persistent congeners dominate. Differences in the degradation rate of PCBs between composting and anaerbically degestion of the waste were also observed. A third indication of a contamination source in the collection chain is the presence of the n-alkanes in the fresh and anaerobically digested household waste, which suggest a petrogenic rather than a biogenic origin. Since the major part of the organic fraction of household waste is of plant origin, much of which is treated with pesticides, it was expected to find pesticides in the waste. Many of the pesticides were not degraded during composting or anaerobic digestion, and two that were not found in the waste were found in compost or anaerobically sludge. In these cases the organic bulk material is mineralized more rapidly than the pesticides. The anaerobic biotransformation of nonylphenol mono- and diethoxylates (NPEOI-2) was studied in sludge, landfilled sludge and landfilled municipal solid waste. The NPEO1-2 are degradation products of nonylphenol ethoxylates (heavy duty surfactants) and are further degraded to nonylphenol (NP) which is far more persistent and ecotoxic than its parental compo

Issues arising when interpreting results from an in vitro assay for estrogenic activity

Concern about possible adverse effects caused by the inadvertent exposure of humans and wildlife to endocrine-active chemicals, has led some countries to develop an in vivo–in vitro screening program for endocrine effects. In this paper, a previously described estrogen-inducible recombinant yeast strain (Saccharomyces cerevisiae) is used to investigate a number of issues that could potentially lead to the mislabeling of chemicals as endocrine disruptors. The chemicals studied were: 17-estradiol, dihydrotestosterone, testosterone, estradiol-3-sulfate, 4-nonylphenol, 4-tert-octylphenol, 4-tert-butylphenol, bisphenol-A, methoxychlor, 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane, butyl benzyl phthalate, 4-hydroxytamoxifen, and ICI 182,780. Alterations in assay methodology (for example, incubation time, initial yeast cell number, and the use of different solvents) did not affect the potency of bisphenol-A and 4-nonylphenol relative to 17-estradiol, but did alter the apparent potency of butyl benzyl phthalate. Other issues (including the metabolic activation of methoxychlor, the chemical purity of a steroid metabolite and unusual chemical artifacts observed with alkylphenolic chemicals) which affect data interpretation are described. Many of the issues raised will also affect other in vitro assays for endocrine activity, and some will be relevant to the interpretation of data from in vivo assays. These examples illustrate that considerable care and thought must be applied when interpreting results derived from any single assay. Only by using a suite of assays will we minimize the chances of wrongly labeling chemicals as endocrine disruptors

A critical review of the formation of mono- and dicarboxylated metabolic intermediates of alkylphenol polyethoxylates during wastewater treatment and their environmental significance

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 Taylor & Francis.Alkylphenoxyacetic acids, the metabolic biodegradation products of alkylphenol ethoxylates, are commonly found in wastewaters and sewage effluents. These persistent hydrophilic derivatives possess intrinsic estrogenic activity, which can mimic natural hormones. Their concentrations increase through the sewage treatment works as a result of biodegradation and biotransformation, and when discharged can disrupt endocrine function in fish. These acidic metabolites represent the dominant alkylphenolic compounds found in wastewater effluent and their presence is cause for concern as, potentially, through further biotransformation and biodegradation, they can act as sources of nonylphenol, which is toxic and estrogenic. The authors aim to assess the mechanisms of formation as well as elimination of alkylphenoxyacetic acids within conventional sewage treatment works with the emphasis on the activated sludge process. In addition, they evaluate the various factors influencing their degradation and formation in laboratory scale and full-scale systems. The environmental implications of these compounds are considered, as is the need for tertiary treatment processes for their removal

Fate and occurrence of alkylphenolic compounds in sewage sludges determined by liquid chromatography tandem mass spectrometry

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2009 Taylor & Francis.An analytical method has been developed and applied to determine the concentrations of the nonionic alkylphenol polyethoxylate surfactants and their metabolites, alkylphenoxy carboxylates and alkyphenols, in sewage sludges. The compounds were extracted with methanol/acetone (1:1 v/v) from sludge, and concentrated extracts were cleaned by silica solid‐phase extraction prior to determination by liquid chromatography tandem mass spectrometry. The recoveries, determined by spiking sewage sludge at two concentrations, ranged from 51% to 89% with method detection limits from 6 µg kg−1 to 60 µg kg−1. The methodology was subsequently applied to sludge samples obtained from a carbonaceous activated sludge plant, a nitrifying/denitrifying activated sludge plant and a nitrifying/denitrifying activated sludge plant with phosphorus removal. Concentrations of nonylphenolic compounds were two to three times higher than their octyl analogues. Long‐chain nonylphenol polyethoxylates (NP3–12EO) ranged from 16 µg kg−1 to 11754 µg kg−1. The estrogenic metabolite nonylphenol was present at concentrations ranging from 33 µg kg−1 to 6696 µg kg−1.Public Utilities Board of Singapore, Thames Water and Yorkshire Water

Intracellular proteome expression during 4-n-nonylphenol biodegradation by the filamentous fungus Metarhizium robertsii

4-n-nonylphenol (4-n-NP) is an endocrine disrupting compound (EDC); pollutants that cause serious disturbances in the environment. This study shows the degradation pathway and initial proteome analysis in cultures of a fungus that actively degrades 4-n-NP, Metarhizium robertsii. The research revealed the presence of 14 4-n-NP metabolites formed as a result of the oxidation of the alkyl chain and benzene ring, which leads to the complete decomposition of the compound. Based on the trend and quantitative analysis of the formation of 4-n-NP derivatives, the best conditions for proteome analysis were established. The data collected allowed the formulation of an explanation of the microorganism's strategy towards the removal of 4-n-NP. The main groups of proteins engaged in the removal of the xenobiotic are: oxidation-reduction systems related to nitroreductase-like proteins, ROS defense systems (peroxiredoxin and superoxide dismutase), the TCA cycle and energy-related systems. Principal components analysis was applied to unidentified proteins, resulting in the formulation of three subgroups and initial classification of these proteins