Biodegradation of natural and synthetic endocrine-disrupting chemicals by aerobic granular sludge reactor: Evaluating estrogenic activity and estrogens fate

Advancements and Challenges in Nanoscale Zero-Valent Iron-Activated Persulfate Technology for the Removal of Endocrine-Disrupting Chemicals

Endocrine-disrupting chemicals are a new class of pollutants that can affect hormonal metabolic processes in animals and humans. They can enter the aquatic environment through various pathways and gradually become enriched, thus posing a serious threat to the endocrine and physiological systems of both animals and humans. Nano zero-valent iron has promising applications in endocrine disruptor removal due to its excellent reducing properties and high specific surface area. However, given the dispersed focus and fragmented results of current studies, a comprehensive review is still lacking. In this paper, it was analyzed that the types of endocrine disruptors and their emission pathways reveal the sources of these compounds. Then, the main technologies currently used for endocrine disruptor treatment are introduced, covering physical, chemical, and biological treatment methods, with a special focus on persulfate oxidation among advanced oxidation technologies. Also, the paper summarizes the various activation methods of persulfate oxidation technology and proposes the nZVI-activated persulfate technology as the most promising means of treatment. In addition, this paper reviews the research progress of different modification methods of nZVI in activating persulfate for the removal of EDCs. Finally, the discussion includes recycling studies of nZVI/PS technology and emphasizes the urgency and importance of endocrine disruptor treatment. The review of this paper provides further scientific basis and technical support for nZVI/PS technology in the field of endocrine disruptor management.

Evaluating the estrogen degradation potential of laccase and peroxidase from Bacillus ligniniphilus L1 through integrated computational and experimental approaches

This study investigated the degradation potential of laccase and catalase-peroxidase from the extremophilic marine bacterium Bacillus ligniniphilus L1 against endogenous and synthetic estrogen compounds using an integrated computational and experimental approach. Molecular docking identified five estrogen compounds exhibiting reliable bindings with enzymes, which were then subjected to enzyme activity assays. The degradation potential of the two enzymes against five selected estrogen compounds were investigated and compared with their commercial counterparts. Laccase from L1 showed higher degradation potential against estrone (47.02 % without and 62.21 % with ABTS) compared to commercial laccase (39 % without and 54.20 % with ABTS). For estradiol valerate, commercial laccase showed a slightly higher degradation (52.47 %) than L1 laccase (49.94 %), but with ABTS, L1 laccase performed better (74.15 % vs. 68.03 %). Notably, L1 catalase-peroxidase demonstrated significantly higher degradation for all tested compounds compared to its commercial counterpart with efficiencies of 96.16 %, 89.09 %, 74.94 %, 64.91 %, and 62.80 % against estropipate, quinestrol, estradiol valerate, estriol and estrone, respectively, revealing its potential for commercial applications. Molecular dynamics simulations revealed the interaction and stability of enzyme-estrogen complexes, with MMGBSA binding energy calculations supporting experimental results. These findings highlight the usefulness of the computational approach in elucidating the molecular mechanisms underlying enzyme-mediated bioremediation of environmental contaminants.

When aerobic granular sludge faces emerging contaminants: A review

The evolution of emerging contaminants (ECs) has caused greater requirements and challenges to the current biological wastewater treatment technology. As one of the most promising biological treatment technologies, the aerobic granular sludge (AGS) process also faces the challenge of ECs. This study summarizes the recent progress and characteristics of several representative ECs (persistent organic pollutants, endocrine disrupting chemicals, antibiotics, and microplastics) in AGS systems that have garnered widespread attention. Additionally, the biodegradation and adsorption mechanisms of ECs were discussed, and the interactions between various ECs and AGS was elucidated. The importance of extracellular polymeric substances for the stabilization of AGS and the removal of ECs is also discussed. Knowledge gaps and future research directions that may enable the practical application of AGS are highlighted. Overall, AGS processes show great application potential and this review provides guidance for the future implementation of AGS technology as well as elucidating the mechanism of its interaction with ECs.

Water a major source of endocrine-disrupting chemicals: An overview on the occurrence, implications on human health and bioremediation strategies

Endocrine disrupting chemicals (EDCs) are toxic compounds that occur naturally or are the output of anthropogenic activities that negatively impact both humans and wildlife. A number of diseases are associated with these disruptors, including reproductive disorders, cardiovascular disorders, kidney disease, neurological disorders, autoimmune disorders, and cancer. Due to their integral role in pharmaceuticals and cosmetics, packaging companies, agro-industries, pesticides, and plasticizers, the scientific awareness on natural and artificial EDCs are increasing. As these xenobiotic compounds tend to bioaccumulate in body tissues and may also persist longer in the environment, the concentrations of these organic compounds may increase far from their original point of concentrations. Water remains as the major sources of how humans and animals are exposed to EDCs. However, these toxic compounds cannot be completely biodegraded nor bioremediated from the aqueous medium with conventional treatment strategies thereby requiring much more efficient strategies to combat EDC contamination. Recently, genetically engineered microorganism, genome editing, and the knowledge of protein and metabolic engineering has revolutionized the field of bioremediation thereby helping to breakdown EDCs effectively. This review shed lights on understanding the importance of aquatic mediums as a source of EDCs exposure. Furthermore, the review sheds light on the consequences of these EDCs on human health as well as highlights the importance of different remediation and bioremediation approaches. Particular attention is paid to the recent trends and perspectives in order to attain sustainable approaches to the bioremediation of EDCs. Additionally, rigorous restrictions to preclude the discharge of estrogenic chemicals into the environment should be followed in efforts to combat EDC pollution.

Estrogen adsorption from an aqueous solution on the chitosan nanoparticles

In this research, chitosan nanoparticles as an efficient and reusable adsorbent with adsorption capacity of 5.79 mg/g, surface area of 62 m²/g and pH_pzc of 8.07 were applied to remove the ethinylestradiol (as a sample of estrogen) from an aqueous wastewater. The chitosan nanoparticles were characterized by SEM, XRD and FT-IR analyses. Four independent variables involving contact time, adsorbent dosage, pH, and initial concentration of estrogen were applied to design the experiments by Design Expert software (CCD under RSM). In fact, number of experiments was minimized and the operating conditions were optimized for the maximum estrogen removal. The results indicated that three independent variables (contact time, adsorbent dosage, and pH) increment increased the estrogen removal while the estrogen initial concentration enhancement decreased the removal due to the concentration polarization phenomenon. The optimum conditions for the estrogen removal (92.50 %) on the chitosan nanoparticles were found at contact time of 220 min, adsorbent dosage of 1.45 g/l, pH of 7.3 and estrogen initial concentration of 5.7 mg/l. Moreover, the Langmuir isotherm and pseudo-second order models could properly legitimize estrogen adsorption process on the chitosan nanoparticles.

Bioaugmentation removal and microbiome analysis of the synthetic estrogen 17α-ethynylestradiol from hostile conditions and environmental samples by Pseudomonas citronellolis SJTE-3

Synthetic estrogens are emerging environmental contaminants with great estrogenic activities and stable structures that are widespread in various ecological systems and significantly threaten the health of organisms. Pseudomonas citronellolis SJTE-3 is reported to degrade the synthetic estrogen 17α-ethynylestradiol (EE2) efficiently in laboratory conditions. In this work, the environmental adaptability, the EE2-degrading properties, and the ecological effects of P. citronellolis SJTE-3 under different hostile conditions (heavy metals and surfactants) and various natural environment samples (solid soil, lake water, and pig manure) were studied. Strain SJTE-3 can tolerate high concentrations of Zn²⁺ and Cr³⁺, but is relatively sensitive to Cu²⁺. Tween 80 of low concentration can significantly promote EE2 degradation by strain SJTE-3, different from the repressing effect of Triton X-100. High concentration of Tween 80 prolonged the lagging phase of EE2-degrading process, while the final EE2 removal efficiency was improved. More importantly, strain SJTE-3 can grow normally and degrade estrogen stably in various environmental samples. Inoculation of strain SJTE-3 removed the intrinsic synthetic and natural estrogens (EE2 and estrone) in lake water samples in 4 days, and eliminated over 90% of the amended 1 mg/L EE2 in 2 days. Bioaugmentation of strain SJTE-3 in EE2-supplied solid soil and pig manure samples achieved a removal rate of over 55% and 70% of 1 mg/kg EE2 within 2 weeks. Notably, the bioaugmentation of extrinsic strain SJTE-3 had a slight influence on indigenous bacterial community in pig manure samples, and its relative abundance decreased significantly after EE2 removal. Amendment of EE2 or strain SJTE-3 in manure samples enhanced the abundance of Proteobacteria and Actinobacteria, implying their potential in utilizing EE2 or its metabolites. These findings not only shed a light on the environment adaptability and degradation efficiency of strain SJTE-3, but also provide insights for bioremediation application in complex and synthetic estrogen polluted environments.

Exploration of the effect of simultaneous removal of EDCs in the treatment process of different types of wastewater

The SPE-HPLC-MS/MS method was used to investigate the concentration distribution of nine types of estrogens in 18 locations of pollution source along the Jiuzhou River belonging to river systems in Guangdong province and Guangxi Zhuang autonomous region in China, and the estrogenic activity and potential ecological risks were evaluated by calculating the estradiol equivalency (EEQ). The results showed that the calculated estradiol equivalents (cEEQs) of wastewater treatment plants from 17 locations were all higher than 1 ng/L. To further study the removal effect of the treatment process on the estrogens, the pig breeding wastewater from P4 and the municipal wastewater from P13, as well as the black-odorous water, were sampled and surveyed during the entire process. It turned out that estrogens were effectively removed after nitrification activated sludge treatment. Meanwhile, there was a positive correlation between the removal of NH₃-N, total nitrogen (TN) and total phosphorus (TP) and the removal of endocrine disrupting chemicals (EDCs). It is shown in the study the secondary treatment process has achieved a significant effect on the removal of estrogen in both the wet and dry periods and that there has been a positive correlation between the activities of total phosphorus compounds, nitrogen-based compounds and the removal of EDCs.

Wastewater toxicity removal: Integrated chemical and effect-based monitoring of full-scale conventional activated sludge and membrane bioreactor plants

The literature is currently lacking effect-based monitoring studies targeted at evaluating the performance of full-scale membrane bioreactor plants. In this research, a monitoring campaign was performed at a full-scale wastewater treatment facility with two parallel lines (traditional activated sludge and membrane bioreactor). Beside the standard parameters (COD, nitrogen, phosphorus, and metals), 6 polynuclear aromatic hydrocarbons, 29 insecticides, 2 herbicides, and 3 endocrine disrupting compounds were measured. A multi-tiered battery of bioassays complemented the investigation, targeting different toxic modes of action and employing various biological systems (uni/multicellular, prokaryotes/eukaryotes, trophic level occupation). A traffic light scoring approach was proposed to quickly visualize the impact of treatment on overall toxicity that occurred after the exposure to raw and concentrated wastewater. Analysis of the effluents of the CAS and MBR lines show very good performance of the two systems for removal of organic micropollutants and metals. The most noticeable differences between CAS and MBR occurred in the concentration of suspended solids; chemical analyses did not show major differences. On the other hand, bioassays demonstrated better performance for the MBR. Both treatment lines complied with the Italian law's "ecotoxicity standard for effluent discharge in surface water". Yet, residual biological activity was still detected, demonstrating the adequacy and sensitivity of the toxicological tools, which, by their inherent nature, allow the overall effects of complex mixtures to be taken into account.

Endocrine disrupting chemicals (EDCs) in environmental matrices: Occurrence, fate, health impact, physio-chemical and bioremediation technology

Endocrine disrupting chemicals (EDCs) are an emerging category of toxicity that adversely impacts humans and the environment's well-being. Diseases like cancer, cardiovascular risk, behavioral disorders, autoimmune defects, and reproductive diseases are related to these endocrine disruptors. Because these chemicals exist in known sources such as pharmaceuticals and plasticizers, as well as non-point sources such as agricultural runoff and storm water infiltration, the interactive effects of EDCs are gaining attention. However, the efficiency of conventional treatment methods is not sufficient to fully remediate EDCs from aqueous environments as the occurrence of EDC bioremediation and biodegradation is detected in remediated drinking water. Incorporating modification into current remediation techniques has to overcome challenges such as high energy consumption and health risks resulting from conventional treatment. Hence, the use of advanced psychochemical and biological treatments such as carbon-based adsorption, membrane technology, nanostructured photocatalysts, microbial and enzyme technologies is crucial. Intensifying environmental and health concerns about these mixed contaminants are primarily due to the lack of laws about acute concentration limits of these EDCs in municipal wastewater, groundwater, surface water, and drinking water. This review article offers evidence of fragmentary available data for the source, fate, toxicity, ecological and human health impact, remediation techniques, and mechanisms during EDC removal, and supports the need for further data to address the risks associated with the presence of EDCs in the environment. The reviews also provide comprehensive data for biodegradation of EDCs by using microbes such as fungi, bacteria, yeast, filamentous fungi, and their extracellular enzymes.

Enhancing biological nitrogen and phosphorus removal performance in aerobic granular sludge sequencing batch reactors by activated carbon particles

Long start-up periods for aerobic granular sludge (AGS) formation and establishment of P removal pathways are challenges for widespread implementation of AGS process. External additives such as activated carbon (AC) attracted interest for accelerating AGS formation. However, the roles of AC in granulation and biological nutrient removal (BNR) are not understood. Here, the role of AC was investigated in decreasing start-up periods in AGS formation and BNR under different carbon substrate conditions (i.e., acetate (HAc), propionate (HPr) and HAc-HPr) in sequencing batch reactors (SBRs). AC addition increased aggregation index and settleability of activated sludge (AS) inoculum which minimized AS washout from SBRs. AC addition hastened AGS formation and establishment of BNR pathways by facilitating AS retention and biofilm formation. Feeding HAc or HAc-HPr supported better granulation (MLSS: 6-7 g l^-1, SVI: 30-40 ml g^-1) than HPr (MLSS: 4 g l^-1, SVI: 70). The start-up periods for efficient total nitrogen (TN) removals were decreased to 22 and 16 d from 38 to 25 d, respectively, in AC augmented SBRs fed with either HAc or HAc-HPr. TN removals were higher at ≥95% in HAc or HAc-HPr fed SBRs. Total phosphorus (TP) removals were also higher in AC-augmented SBRs at 80% and ≥90% in HAc and HAc-HPr fed SBRs, respectively. In contrast, TN and TP removals were lower at 70% and 35%, respectively, in HPr fed SBR. Ammonium was primarily removed via nitritation-denitritation pathway. Phosphorus removal was at 1.7 to 2-fold higher in AC augmented SBRs and driven by enhanced biological phosphorus removal (EBPR) pathway. MiSeq sequencing and qPCR revealed higher enrichment of polyphosphate accumulating organisms (PAOs), denitrifying PAOs, and ammonia oxidizers in AC-augmented SBRs fed with HAc or HAc-HPr. This study demonstrates that AC addition can be considered for enrichment of PAOs and establishment of EBPR in aerobic granular SBRs.

Aerobic granulation of nitrifying activated sludge enhanced removal of 17α-ethinylestradiol

The positive correlation between the nitrification activity of activated sludge and 17α-ethinylestradiol (EE2) removal has been widely reported. However, up to now the effect of the granulation of nitrifying activated sludge (NAS) on EE2 removal has not been determined. In this study, nitrifying granular sludge (NGS) exhibited more effective EE2 removal efficiency with 3.705 μgEE2∙(gMLSS∙h)^-1 in a sequential batch reactor (SBR). Through the artificial neural network (ANN) model and Spearman correlation analysis, nitrite accumulation was demonstrated to be the key factor affecting EE2 removal. Notably, under the same aeration condition (0.15 L/min), nitrite accumulation was more easily achieved in NGS because of its dense structure. Full-length 16S rRNA gene sequencing suggested that EE2 could strongly influence the microbial communities of NAS and NGS. NGS exhibited an increase in community diversity and richness, but NAS exhibited a decrease. In addition, the relative abundance of Nitrosomonas (ammonia-oxidizing bacteria, AOB) decreased considerably in both NAS and NGS, whereas the expression of amoA and nirK genes in Nitrosomonas was upregulated. It was suggested that Nitrosomonas was forced to regulate its gene expression to resist the negative effects of EE2. Denitrifying bacteria, such as Comamonas, were enriched in both NAS and NGS, and there were more species of heterotrophs that can degrade micropollutants in NGS with exposure to EE2. The transformation pathways of EE2 were uniform in NAS and NGS. Ammonia monooxygenase (AMO) in AOB directly biotransformed EE2 while reactive species produced by AOB chemically transformed EE2. Heterotrophs degraded EE2 and its transformation products (TPs) generated by AOB. According to TPs and microbial structure, NGS exhibited better performance than NAS regarding the collaborative removal of EE2 by AOB and heterotrophs. These results provide important information for the development and application of NGS to treat wastewater containing estrogen and high-strength ammonium.

Rapidly achieving partial nitrification of municipal wastewater in enhanced biological phosphorus removal (EBPR) reactor: Effect of heterotrophs proliferation and microbial interactions

Stable nitritation is the major challenge for short-cut nitrogen removal from municipal wastewater. This paper demonstrated a rapid achievement of partial nitrification (PN) in an enhanced biological phosphorus removal (EBPR) reactor treating domestic wastewater. Polyphosphate accumulating organisms (PAOs) were enriched operated at a short aerobic HRT (2.0 h) and SRT (10 d), with satisfactory phosphorus removal efficiency (95.9%). Both of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were elutriated simultaneously. Interestingly, AOB recovered much faster than NOB by a subsequent extension of aerobic HRT and SRT, resulting in a rapid development of PN within 15 days. Ammonia oxidation rates of AOB significantly increased by 44.2%, facilitating a high nitrite accumulation rate (NAR) of 95.8%. Genus Tetrasphaera, Halomonas, Paracoccus and Candidatus_Accumulibacter belonging to PAOs accounted for 4.6%. The proliferation of heterotrophs, typically as PAOs, maximized the microbial competition against NOB by favoring AOB activity and synergy with functional bacteria.