Chemosphere最新文献

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .

Wastewater treatment processes are continually evolving to meet stringent environmental standards while optimizing energy consumption and operational costs. With significant advantages over more traditional approaches, the anammox process has become a hopeful substitute for nitrogen removal. The objective of this work was to evaluate upflow anaerobic sludge blanket reactor (UASBR), moving bed biofilm reactor (MBBR), and sequential batch reactor (SBR) among diverse reactor configurations, in culturing anammox bacteria and achieving nitrogen removal efficiencies. Synthetic wastewater containing NH₄⁺-N concentration and NO₂^--N concentration of 80 ± 5 mg/L was introduced to the reactors, and observations were made for up to 150 days. This study found that the MBBR demonstrated superior anammox activity, achieving a total nitrogen removal efficiency (TNRE) of 94 ± 3%, SBR exhibited a TNRE of approximately 85 ± 3%, while UASB displayed TNRE of 73 ± 3%. The effect of varying carbon-to-nitrogen (C/N) ratios on nitrogen removal efficiencies was investigated, revealing a decrease in TNRE as the C/N ratio increased from 3 to 8. This study demonstrated the enhancing and inhibitory effects of C/N ratio, NO₂^--N, and Fe concentrations. It revealed that Fe concentrations between 1 and 5 mg/L increase specific anammox activity (SAA), while concentrations between 5 and 10 mg/L negatively impact it. Additionally, NO₂^--N concentrations above 150 mg/L significantly reduce SAA. Furthermore, a 16S rRNA metagenomic analysis of MBBR sludge samples revealed the significant presence of Candidatus Brocadia bacteria, constituting 20.4% of the microbial community. This research highlights the potential of MBBR in fostering anammox reactions and achieving efficient nitrogen removal in wastewater treatment applications.

This study investigated the green synthesis of silver nanoparticles (Ag-NPs) and zinc oxide nanoparticles (ZnO-NPs) using an aqueous extract of stingless bee honey (SBH) as a reducing and stabilising agent. The rich compositions of SBH containing flavonoids, phenolics, organic acids, sugars, and enzymes makes the SBH extract an ideal biocompatible precursor for the NPs synthesis. Physicochemical characterisation of the synthesised NPs was performed using UV-Vis spectroscopy, FESEM, TEM, XRD, and FTIR spectroscopy. The results revealed that the Ag-NPs and ZnO-NPs exhibited polydispersity, with size ranges between 25-50 nm and 15-30 nm, respectively. A majority of the NPs possessed a spherical morphology. Furthermore, the study evaluated the antimicrobial activity of the SBH-based NPs against gram-positive (Staphylococcus aureus, ATCC 43300) and gram-negative (Escherichia coli, ATCC 25922) bacteria. The findings demonstrated significantly higher antimicrobial efficacy of the Ag-NPs with a zone of inhibition (ZOI) of 16.91 mm against S. aureus, and 17.43 mm against E. coli compared to the ZnO-NPs which having a ZOI of 13.05 mm and 14.01 mm, respectively. Notably, cytotoxicity assays revealed no adverse effects of the synthesised NPs on normal mouse fibroblast (3T3) and human lung fibroblast (MRC5) cells up to 100 μg/ml of concentration. These findings suggest the potential of SBH-based Ag-NPs and ZnO-NPs as safe and effective antibacterial agents for various applications, including pharmaceuticals, cosmetics, ointments, and lotions.

The objective of the subsequent study was to examine the probability of PFAS (per- and polyfluorinated alkyl substances) binding to various NHRs (nuclear hormone receptors) and to identify their structural features that contribute most to the binding score (BS). We evaluated the BS for PFAS in relation to 7 selected NHRs - 4 with additional antagonist forms (Retinoid X receptor alpha - RXRα, Liver X receptor alpha - LXRα, Liver X receptor beta - LXRβ, Estrogen receptor alpha - ERα, Estrogen receptor alpha antagonist - anti-ERα, Estrogen receptor beta - ERβ, Estrogen receptor beta antagonist - anti-ERβ, Glucocorticoid receptor - GR, Glucocorticoid receptor antagonist - anti-GR, Androgen receptor - AR, Androgen receptor antagonist - anti-AR). We based our study on the results of molecular docking, which we used to develop MLR-QSAR (Multiple Linear Regression - Quantitative Structure-Activity Relationship) models. The models we developed allowed us to predict the BS for an extensive set of PFAS compounds from the NORMAN database (more than 4000) - virtual screening. The probability of PFAS binding to selected receptors was determined by structural features such as particle size, branching, and fluorine content. These variables were also identified in the literature reports of experimental studies as the most important for this group of compounds. The research focused on receptors from the terpenoid group. The RXRα, LXRα and β, GR, and anti-GR receptors were shown to be the group less likely to be affected by PFAS. Sex hormones such as AR, anti-AR, ERα and ERβ with their antagonist forms are the most affected.

This work focused on the transformation behavior of the emerging beaytlmethodeyammonium chbride (BAC-12) disinfectant existed in the treatment of medical sewage during its disinfection treatment. The degradation ability of ozone (O₃) to BAC-12 was the best, followed by UV/NaOCl, UV, and NaOCl. The enhancement of BAC-12 in UV/NaOCl system is caused by the combined effect of UV photolysis, reactive chlorine species (RCS), and •OH. The transformation products of BAC-12 in the disinfection treatment were detected, and the chemical structure of products was rationalized by frontier molecular orbital and transition state theory methodologies. According to the ecological structure-activity relationship (ECOSAR) assessment, the intermediates of BAC-12 in UV, NaOCl, and UV/NaOCl treatments had lower half lethal concentration (LC₅₀) and chronic toxicity (ChV) values with a higher ecotoxicity than BAC-12. O₃ disinfection treatment of these toxic intermediates can significantly reduce the toxicity of the BAC-12 solution. This work provides necessary information on the potential environmental risks of BAC-12 arising from different disinfection methods in the treatment of medical wastewater.

Commercial grease interceptors (GIs), commonly used in food service establishments, are primarily designed to treat fat, oil and grease (FOG) from handwash sink (HS) wastewater. They are generally less effective for removing highly concentrated FOG from dishwasher (DW) effluents which contain highly emulsified FOG with complex long-chain fatty acids (LCFAs). Furthermore, standard testing of GIs uses diesel fuel to simulate FOG separation; however, the flow properties of typical cooking oils and animal fats differ significantly from diesel. We developed a novel GI (bench-scale with 72 L capacity) and examined the impact of various baffle configurations on FOG removal efficiency using samples containing representative FOG components of cooked oil, fat and food solids. The results demonstrated that the installation of two short baffles projecting from the top along with one short baffle projecting from the bottom in the first chamber, and another short baffle projecting from the top in the second chamber, led to FOG removal efficiencies of up to 88% and 40% for HS and DW effluents, respectively, at a hydraulic retention time (HRT) of 44 min. The short baffles acted as barriers, thus enhancing the loss of kinetic energy, subsequently ensuring a quiescent flow condition, resulting in an increased HRT for effective FOG separation. The addition of alum as coagulant at 200 mg/L (18.2 mg of Al³⁺/L) significantly enhanced the removal of FOG from treated DW effluents (up to 87%), effectively reducing the concentrations of various extra-LCFAs, such as paullinic (C20:1), arachidic (C20:0), eicosadienoic acid (C20:2), mead (C20:3), eicosapentaenoic (C20:5), erucic (C22:1), cervonic (C22:6), tricosanoic acid (C23:0), lignoceric (C24:0) and nervonic (C24:1) acid by up to 99%. These findings provide significant insights into the advanced GI design, offering a proactive solution to prevent fatberg formation while promoting a more sustainable and economically viable approach to sewer management.

Selenium (Se) release from anthropogenic activities such as mining, power generation, and agriculture poses considerable environmental and ecological risks. Increasing prevalence and awareness of Se-related issues have driven the development of many innovative Se treatment technologies. Photocatalysis has shown promise towards Se removal from industrial wastewaters with minimal residuals, and is generally considered a low-cost, robust, non-toxic, and potentially solar-powered method. Despite this, its real-world application towards environmental remediation remains extremely limited. This is because research into practical considerations, such as photocatalyst stability and reusability, is often overlooked or understudied in favor of developing academically interesting but impractical materials. In this work, commercial anatase TiO₂ is stress tested through fifteen cycles of reuse towards the photocatalytic reduction and removal of selenate in synthetic mining-influenced brine (SMIB) without washing or regeneration. Remarkably, selenate removal exceeds 99.3% throughout all cycles. In situ Se-TiO₂ heterojunction formation, and changes to its properties including Se loading, particle size, and crystal phase, are characterized through X-ray absorption spectroscopy, scanning transmission electron microscopy, and diffuse reflectance UV/vis, while their effects on catalyst performance are elucidated. This work underscores the importance of catalyst recyclability for practical photocatalytic environmental remediation and discusses the effects of extensive use on photocatalyst performance.

The positioning of the hydroxy group plays a crucial role in the coordination of Schiff bases with copper ions and their antibacterial effectiveness. This potential is an area of interest for future exploration, although no specific studies have been conducted. This study aims to reveal the significance of the positioning of the hydroxy group in the ability of the Schiff base to coordinate with copper ion and its antibacterial efficacy against E. coli and S. aureus. By utilizing ortho-vanillin and para-vanillin as precursors, we successfully synthesized Schiff bases HL1 (ortho) and L2 (para), which were confirmed through Fourier Transform Infrared (FT-IR) and Nuclear Magnetic Resonance (NMR) analyses. HL1 forms the CuL1 complex as a bidentate ligand with N, O donor atoms, while L2 only provides a single N donor atom, forming the CuL2 complex but retaining a free hydroxy group. Crystallographic analysis revealed a tetragonal crystal system for the Schiff base and orthorhombic for the complex. Electronic transition analysis supported by Density Functional Theory (DFT) studies indicated a distorted square plane geometry for the CuL1 and CuL2 complexes. The in vitro antibacterial assessment against E. coli and S. aureus revealed that the CuL1 and CuL2 complexes exhibited significantly better activity than Schiff bases HL1 and L2. Moreover, CuL2 exhibits greater bioactivity against both bacterial strains compared to CuL1. This difference could be attributed to a free hydroxy group, supported by computational analysis. Our findings suggest that the formation of complexes and the presence of free hydroxy groups may enhance the antibacterial activity of the drug.

Water scarcity in the Mediterranean area has increased the number of intermittent rivers. Recently, hyporheic zones (HZ) of intermittent rivers have gained attention since a substantial part of the stream's natural purification capacity is located within these zones. Thus, understanding the flow dynamics in HZs is crucial for gaining insights into the degradation of organic micropollutants. A lab-scale study using column experiments was conducted in an attempt to elucidate the environmental processes accounting for the biodegradation capacity of the HZ under flow intermittency. A mixture of six compounds including pesticides (chloranthraniliprole, fluopyram and trifloxystrobin) and pharmaceuticals (venlafaxine, amisulpride and paroxetine) spiked at 1 μg/L level was used for degradation kinetic studies and at 1 mg/L for transformation products identification using suspect/non-target liquid chromatography high-resolution mass spectrometry approaches. The experiments lasted 60 days, divided into two 14-day phases: one before and one after a 5-week desiccation period. Bacterial community was charaterized by high-throughput DNA sequencing. The results suggested that intermittent flows stimulated the biodegradation of three compounds namely fluopyram, trifloxystrobin and venlafaxine, showing a large range of biodegradation profiles in batch water/sediment testing system according to OECD 308 tests. Biodegradation rate enhancement was ascribed to the occurrence of additional transformation routes after the desiccation period of river sediment, with the formation of new transformation products reported for the first time in the present work. 16S rDNA sequencing revealed that the desiccation period favored the growth of nitrifying and denitrifying bacteria which could partially explain the emergence of the new transformation pathways and most specifically those leading to N-oxide derivatives. Identification of transformation products also revealed that reductive transformation routes were relevant for this study, being dehydrogenation, dehalogenation, ether bond cleavage and sulfone reduction into sulphide important reactions. These results suggest that the intermittent flow conditions can influence the HZ biodegradation capacity.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). .