Veterinary pharmaceutical as emerging contaminants in wastewater and surface water: An overview

Singlet oxygen presenting a higher detoxification potential on enrofloxacin than sulfate and hydroxyl radicals

With the aid of radical and non-radical reactive species (RS), advanced oxidation processes can efficiently degrade emerging organic contaminants including antibiotics but may generate toxic transformation products (TPs). However, the detoxification capacity of popular RS has not been well elucidated. This study compared the detoxification of enrofloxacin (ENR) with three RS-dominated systems: 1O2, SO4•-+•OH, •OH. The toxicity of ENR TPs generated from those systems was evaluated with multiple methods. It was found that the 1O2-dominated system detoxified ENR more effectively than the other systems in terms of microbial respiratory inhibition, developmental toxicity in zebrafish embryos, and three typical molecular biomarkers, including reactive oxygen species (ROS), and lactate dehydrogenase (LDH), and glutathione S-transferase (GST). Based on their chemical structures of ENR TPs projected with UPLC-QTOF-MS/MS, the toxicity prediction tool (T.E.S.T) revealed that the 1O2-dominated system led to more harmless TPs than the others. The results of this study underscore the great potential of 1O2-dominated system in the detoxification of organic contaminants.

Impact of sewage sludge biochar spheres as constructed wetland substrates on antibiotic removal and application

The persistence of antibiotics in wastewater poses significant environmental risks, with sulfadiazine (SDZ) being hardly remove by conventional treatment process. This study evaluated the efficacy of biochar spheres (BC-S) derived from sewage sludge in enhancing the removal of SDZ in plant-free filtration column for discussing the research of vertical flow constructed wetlands (VFCWs). Adsorption experiments showed that the highest adsorption capacity of SDZ by BC-S was 1.79 mg/g with chemisorption mechanism. The filtration columns were filled with BC-S through three filling methods. C1, C2, and C3 employed layered, multi-layered and uniformly mixed filling methods, respectively, to compare the effects of different substrate structures on pollutant removal. Results showed that C3, incorporating biochar spheres in uniform mixing mode, has the best removal performance. C3 achieved an average SDZ removal efficiency of 99.19 %, with effluent concentrations averaging 6.06 ng/L. And the average removal rate for conventional pollutants COD, NH4+-N, and TP were 95.03 %, 73.60 % and 96.91 %, respectively. Moreover, In the three systems, Proteobacteria, Patescibacteria, Bacteroidota and Firmicutes were the main dominant phylum accounting for >50 % of the total. Different filling method inside systems causes the different microbial structure and relative abundance in C1, C2 and C3, resulted in the differences of removal effect. This study offers a promising avenue for advancing the capabilities of constructed wetlands in treating SDZ wastewater.

Upconversion/Downshifting Luminescence Ratio Sensor: Single Nanocomposite for Multiple Antibiotic Detection

Antibiotics are widely used in treating animal and human diseases; thus, the trace detection of antibiotics is crucial and challenging. Currently, the sensors used for antibiotic detection are generally responsive only to a single type of antibiotic. Herein, we designed and prepared a luminescence ratio nanocomposite (UCN-ATPA-Eu3+), in which the 2-Aminoterephthalic acid (ATPA) was used to functionalize upconversion nanoparticles (UCN), and the Eu3+ ion was coordinated at the periphery. The upconversion/downshifting luminescence detection of antibiotics from different categories can be achieved by using the single nanocomposite and switching the excitation light source (385 and 980 nm), and their corresponding mechanisms of detection were demonstrated and discussed. The upconversion detection was based on the Förster resonance energy transfer and inner filter effect between the detection object and the UCN, while the downshifting detection was attributed to the competition absorbance of excitation light between the object and ATPA, and then, the energy was transferred to the coordinated Eu3+ through the antenna effect. After the immunity and selectivity of the nanocomposite were verified, detection of real samples was carried out, which displayed high accuracy and repeatability.

Sunlight-Induced Photocatalytic Removal of Paracetamol Using Au-TiO2 Nanoparticles

Using sunlight as the driving force for photocatalytic processes holds great promise for sustainability. As a starting point for developing a material capable of degrading aquatic pollutants using solar energy as a stimulus, this work focuses on synthesizing Au-TiO2 nanocomposites using the deposition-precipitation method. Characterization of Au-TiO2 nanoparticles was performed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission Electron Microscopy (TEM). A model pollutant, paracetamol, was used to test the synergetic effect of Au (0.05 wt%) nanoparticles (NPs) with TiO2 on photocatalytic activity. The influence of the parameters pH, loading (0.4, 0.8, and 1 g/L), pollutant concentration (20, 30, 40 ppm), and contact time (30, 60, 90, 120, 150, and 180 min) was studied by exposing the NPs to solar radiation. The photocatalytic degradation was most effective at a contact time of 3 h, an initial concentration of 20 ppm, and a pH of 6.8. Under these conditions, paracetamol in 1 g/L of Au-TiO2 nanocomposites can be degraded by more than 99.17% under solar irradiation. As a result of the Au-TiO2 composite's ability to successfully serve as a photocatalyst using sun radiation, water purification processes can be more widespread, cost-effective, and environmentally friendly.

Organic ultraviolet filters in Hainan coral reefs: Distribution, accumulation, and ecological risks

Organic ultraviolet filters (OUVFs) have been widely used as functional ingredients of sunscreen products and have entered into marine ecosystems, particularly in tropical areas where solar UV radiation is strong. These chemicals, with their potential toxicity and ecological risk, have raised widespread concern for the protection of the fragile marine ecosystem of coral reefs. In this study, fourteen OUVFs were analyzed among 24 coral species, together with their habitats including seawater and sediment from the coastal coral reef regions of Hainan Island, South China Sea. Surprisingly, all of fourteen OUVFs were detected in each sample, indicating the wide distribution of OUVFs among sites and samples. Among the fourteen OUVFs, benzophenone-3 (BP-3) and 4-methylbenzylidene camphor (4-MBC) were the most abundant, with concentrations ranging from 35.3 to 75.6 and 38.3 to 61.4 ng/L in seawater, from 13.2 to 25.9 and 7.0 to 17.4 ng/g dw in sediment, and from 4.5 to 21.3 and 4.4 to 19.7 ng/g dw in corals, respectively. Analysis of OUVFs in 24 coral species pointed that OUVFs accumulation in corals is morphology dependent: the highest concentration of OUVFs was identified in Galaxea fascicularis with abundant of polyps and tentacles while the lowest levels of OUVFs were found in Porites mayeri (smooth or lobed surface). In corals, we found that these OUVFs accumulated, depending on the coral species and the types of OUVFs. The ecological risk assessment further indicated that BP-3, 4-MBC and BP-8 had posed risks to corals. In addition, significantly higher concentrations of OUVFs were observed in Sanya (a seaside tourist resort) than in the other sites, suggesting that tourist activity and use of sunscreen products are the key to high inputs of sunscreen agents into marine ecosystem. Overall, our study demonstrates a potential risk role for OUVFs in coral protection in tropical areas where coral bleaching events occur.

Joint action of six-component mixtures based on concentration response curves morphological parameter in acute and long-term toxicity assay

Previous studies found that the multi-component mixtures with hormesis concentration-response curves (CRCs) were divided into three types according to the combined toxicity analysis of the segment-based method and σ2(k∙ECx) (the variance of k∙ECx). In this study, the acute and long-term toxicity of six pollutants and 12 six-component mixtures were assessed using microplate toxicity analyses (MTA). The functional relationship between σ2(k·ECx) and effect ratio (ERx) was determined by means of the independent action (IA) and the ER model to systematically investigate the correlation between mixture types in acute and long-term toxicity. The results indicated that across the entire concentration range, the mixture type of acute toxicity was consistent with short time exposure (0.25 h) measured in the long-term toxicity experiment. In the inhibition effect range, the types of mixtures of acute toxicity remained consistent with the chronic toxicity (exposure for 24 h) in 11 of the 12 mixtures. This study clarified the changes in the joint action of multi-component mixtures on Aliivibrio fischeri in terms of acute and long-term toxicity. The chronic toxicity of the mixtures can be predicted from the acute toxicity results, which provides a theoretical basis for the biological toxicity evaluation of multi-component mixtures.

Simulation and prediction of sulfamethazine migration, transformation and risk diffusion during cross-media infiltration from surface water to groundwater driven by dynamic water level: Machine learning coupled HYDRUS-GMS model

Seasonal water level fluctuations in rivers significantly influenced the cross-media migration, transformation, and risk diffusion of antibiotics from the vadose zone into groundwater. This study developed a coupled model integrating machine learning (ML) with HYDRUS-3D and GMS to accurately predict sulfamethazine migration under dynamic water levels. The predictive accuracy (E≥0.98) of this ML-HYDRUS-GMS model was enhanced by accounting for seasonal water level fluctuations and biogeochemical variability. Significant seasonal differences presented with sulfamethazine diffusion in the vadose zone with the migration rate decreased from 0.06 m/d to 0.02 m/d with the transition from wet to dry seasons. After 6 years of infiltration, it reached groundwater, where lateral migration rates, influenced by seasonal flow variations, were 0.12 m/d in the wet season and decreased to 0.07 m/d in the dry season, with a diffusion range extending to 217 m over 100 years. This discrepant continuous filtration of sulfamethazine and the succession of metabolic pathways induced toxicity range to expand by 65.6 m and the risk to increase to warning level. Sulfamethazine underwent oxidative breakdown in aerobic vadose zone conditions, while anaerobic groundwater conditions led to hydrogenation and reduction, increasing its migration distance.

Optimization of degradation conditions for sulfachlorpyridazine by Bacillus sp. DLY-11 and analysis of biodegradation mechanisms

Sulfachloropyridazine (SCP) is a common sulfonamide antibiotic pollutant found in animal excreta. Finding highly efficient degrading bacterial strains is an important measure to reduce SCP antibiotic pollution. Although some strains with degradation capabilities have been screened, the degradation pathways and biotransformation mechanisms of SCP during bacterial growth are still unclear. In this study, a strain capable of efficiently degrading SCP, named Bacillus sp. DLY-11, was isolated from pig manure aerobic compost. Under optimized conditions (5 % Vaccination dose, 51.5 ℃ reaction temperature, pH=7.92 and 0.5 g/L MgSO4), this strain was able to degrade 97.7 % of 20 mg/L SCP within 48 h. Through the analysis of nine possible degradation products (including a new product of 1,4-benzoquinone with increased toxicity), three potential biodegradation pathways were proposed. The biodegradation reactions include S-N bond cleavage, dechlorination, hydroxylation, deamination, methylation, sulfur dioxide release, and oxidation reactions. This discovery not only provides a new efficient SCP-degrading bacterial strain but also expands our understanding of the mechanisms of bacterial degradation of SCP, filling a knowledge gap. It offers important reference for the bioremediation of antibiotic pollutants in livestock and poultry farming.

Pharmaceutical Pollutants: Ecotoxicological Impacts and the Use of Agro-Industrial Waste for Their Removal from Aquatic Environments

Medicines are pharmaceutical substances used to treat, prevent, or relieve symptoms of different diseases in animals and humans. However, their large-scale production and use worldwide cause their release to the environment. Pharmaceutical molecules are currently considered emerging pollutants that enter water bodies due to inadequate management, affecting water quality and generating adverse effects on aquatic organisms. Hence, different alternatives for pharmaceuticals removal from water have been sought; among them, the use of agro-industrial wastes has been proposed, mainly because of its high availability and low cost. This review highlights the adverse ecotoxicological effects related to the presence of different pharmaceuticals on aquatic environments and analyzes 94 investigations, from 2012 to 2024, on the removal of 17 antibiotics, highlighting sulfamethoxazole as the most reported, as well as 6 non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac and ibuprofen, and 27 pharmaceutical drugs with different pharmacological activities. The removal of these drugs was evaluated using agro-industrial wastes such as wheat straw, mung bean husk, bagasse, bamboo, olive stones, rice straw, pinewood, rice husk, among others. On average, 60% of the agro-industrial wastes were transformed into biochar to be used as a biosorbents for pharmaceuticals removal. The diversity in experimental conditions among the removal studies makes it difficult to stablish which agro-industrial waste has the greatest removal capacity; therefore, in this review, the drug mass removal rate (DMRR) was calculated, a parameter used with comparative purposes. Almond shell-activated biochar showed the highest removal rate for antibiotics (1940 mg/g·h), while cork powder (CP) (10,420 mg/g·h) showed the highest for NSAIDs. Therefore, scientific evidence demonstrates that agro-industrial waste is a promising alternative for the removal of emerging pollutants such as pharmaceuticals substances.

Solar driven highly efficient photocatalyst based on Dy2O3 nanorods deposited on reduced graphene oxide nanocomposite for methylene blue dye degradation

In recent years, the demand for rare earth elements has surged due to their unique characteristics and diverse applications. This investigation focuses on utilizing the rare earth element dysprosium oxide (Dy2O3) for the photocatalytic oxidation of model pollutants under solar light irradiation. A novel RGO-Dy2O3 nanocomposite photocatalyst was developed using a solvothermal approach, Dy2O3 nanorods uniformly deposited onto reduced graphene oxide (RGO) nanosheets. Comprehensive characterization techniques, including Brunner-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), Raman spectroscopy, high resolution - transmittance electron microscopy (HR-TEM), field emission-electron scanning microscopy (FE-SEM), atomic force microscopy (AFM), electron paramagnetic resonance spectroscopy (EPR), photoluminescence spectroscopy (PL), and electrochemical impedance spectroscopy EIS techniques. The UV-visible diffusive reflectance spectroscopy (UV-Vis-DRS) studies revealed a band gap energy of 3.18 eV and a specific surface area of 114 m2/g for the fabricated RGO-Dy2O3 nanocomposite. The RGO-Dy2O3 nanocomposite demonstrated a high photocatalytic degradation efficiency of 98.1% at neutral pH for methylene blue (MB) dye for the dye concentration of 10 ppm. The remarkable photocatalytic performance was achieved within 60 min under solar light irradiation. Reusability tests demonstrated stability, maintaining over 90% photocatalytic efficiency after three cycles. The EPR spectra and quenching experiments confirmed that photogenerated hydroxyl radicals significantly influence the photodegradation processes. The RGO-Dy2O3 nanocomposite photocatalyst, with its green, easy preparation process and recycling capabilities, presents an ideal choice for various applications. It offers a viable alternative for the photocatalytic degradation of organic dyes in real wastewater, contributing to sustainable environmental remediation.

Fate of antibiotic resistance genes and EPS defence mechanisms during simultaneous denitrification and methanogenesis, coupled with the biodegradation of multiple antibiotics under zinc stress

High-strength nitrogen and antibiotics-containing wastewater can be efficiently eliminated by simultaneous denitrification and methanogenesis (SDM). Heavy metals and antibiotics are two critical factors that can lead to horizontal transfer of antibiotic resistance genes (ARGs), which can be simultaneously detected in wastewater. Unfortunately, the impacts of heavy metals on SDM and antibiotic biodegradation have not been fully elucidated. Herein, the effects of SDM and multiple antibiotics biodegradation, extracellular polymeric substances (EPSs) and protein response mechanisms, and ARG fate under Zn(II) stress were comprehensively evaluated. The results indicated that a high level of Zn(II) (≥5 mg/L) stress significantly decreased the degradation rate of multiple antibiotics and suppressed denitrification and methanogenesis. In addition, Zn(II) exposure prompted the liberation of proteins from microbes into the EPSs, and the combination of EPSs with small molecules quenched the original fluorescent components and destroyed the protein structure. The dominant proteins can bind to both Zn(II) and multiple antibiotics through several types of chemical interactions, including metallic and hydrogen bonds, hydrophobic interactions, and salt bridges, relieving the toxicity of harmful substances. Moreover, metagenomic sequencing revealed that the abundance of zinc resistance genes (Zn-RGs), ARGs (mainly tetracyclines), and mobile genetic elements (MGEs) increased under Zn(II) stress. Mantel test illustrated that the ARGs mecD, tetT, and tetB(60) were most affected by MGEs. Moreover, molecular network analysis revealed that several MGEs can bridge metal resistance genes (MRGs) and ARGs, facilitating the horizontal transfer of ARGs. This study provides theoretical guidance for the environmental risk control of antibiotics-containing wastewater treated by an SDM system.

Impact of veterinary pharmaceuticals on environment and their mitigation through microbial bioremediation

Veterinary medications are constantly being used for the diagnosis, treatment, and prevention of diseases in livestock. However, untreated veterinary drug active compounds are interminably discharged into numerous water bodies and terrestrial ecosystems, during production procedures, improper disposal of empty containers, unused medication or animal feed, and treatment procedures. This exhaustive review describes the different pathways through which veterinary medications enter the environment, discussing the role of agricultural practices and improper disposal methods. The detrimental effects of veterinary drug compounds on aquatic and terrestrial ecosystems are elaborated with examples of specific veterinary drugs and their known impacts. This review also aims to detail the mechanisms by which microbes degrade veterinary drug compounds as well as highlighting successful case studies and recent advancements in microbe-based bioremediation. It also elaborates on microbial electrochemical technologies as an eco-friendly solution for removing pharmaceutical pollutants from wastewater. Lastly, we have summarized potential innovations and challenges in implementing bioremediation on a large scale under the section prospects and advancements in this field.

Biopolymer-based beads for the adsorptive removal of organic pollutants from wastewater: Current state and future perspectives

Among biopolymer-based adsorbents, composites in the form of beads have shown promising results in terms of high adsorption capacity and ease of separation from the effluents. This review addresses the potential of biopolymer-based beads to remediate wastewaters polluted with emerging organic contaminants, for instance dyes, active pharmaceutical ingredients, pesticides, phenols, oils, polyaromatic hydrocarbons, and polychlorinated biphenyls. High adsorption capacities up to 2541.76 mg g-1 for dyes, 392 mg g-1 for pesticides and phenols, 1890.3 mg g-1 for pharmaceuticals, and 537 g g-1 for oils and organic solvents have been reported. The review also attempted to convey to its readers the significance of wastewater treatment through adsorption by providing an overview on decontamination technologies of organic water contaminants. Various preparation methods of biopolymer-based gel beads and adsorption mechanisms involved in the process of decontamination have been summarized and analyzed. Therefore, we believe there is an urge to discuss the current state of the application of biopolymer-based gel beads for the adsorption of organic pollutants from wastewater and future perspectives in this regard since it is imperative to treat wastewater before releasing into freshwater bodies.

Sulfur Vacancies in Pyrite Trigger the Path to Nonradical Singlet Oxygen and Spontaneous Sulfamethoxazole Degradation: Unveiling the Hidden Potential in Sediments

Pharmaceutical residues in sediments are concerning as ubiquitous emerging contaminants. Pyrite is the most abundant sulfide minerals in the estuarine and coastal sediments, making it a major sink for pharmaceutical pollutants such as sulfamethoxazole (SMX). However, research on the adsorption and redox behaviors of SMX on the pyrite surface is limited. Here, we investigated the impact of the nonphotochemical process of pyrite on the fate of coexisting SMX. Remarkably, sulfur vacancies (SVs) on pyrite promoted the generation of nonradical species (hydrogen peroxide, H2O2 and singlet oxygen, 1O2), thereby exhibiting prominent SMX degradation performance under darkness. Nonradical 1O2 contributed approximately 73.1% of the total SMX degradation. The SVs with high surrounding electron density showed an advanced affinity for adsorbing O2 and then initiated redox reactions in the sediment electron-storing geobattery pyrite, resulting in the extensive generation of H2O2 through a two-electron oxygen reduction pathway. Surface Fe(III) (hydro)oxides on pyrite facilitated the decomposition of H2O2 to 1O2 generation. Distinct nonradical products were observed in all investigated estuarine and coastal samples with the concentrations of H2O2 ranging from 1.96 to 2.94 μM, while the concentrations of 1O2 ranged from 4.63 × 10-15 to 8.93 × 10-15 M. This dark-redox pathway outperformed traditional photochemical routes for pollutant degradation, broadening the possibilities for nonradical species use in estuarine and coastal sediments. Our study highlighted the SV-triggered process as a ubiquitous yet previously overlooked source of nonradical species, which offered fresh insights into geochemical processes and the dynamics of pollutants in regions of frequent redox oscillations and sulfur-rich sediments.

Efficient Sequential Detection of Two Antibiotics Using a Fiber-Optic Surface Plasmon Resonance Sensor

Antibiotic residues have become a worldwide public safety issue. It is vital to detect multiple antibiotics simultaneously using sensors. A new and efficient method is proposed for the combined detection of two antibiotics (enrofloxacin (Enro) and ciprofloxacin (Cip)) in milk using surface plasmon resonance (SPR) sensors. Based on the principle of immunosuppression, two antibiotic antigens (for Enro and Cip) were immobilized on an optical fiber surface with conjugates of bovine serum albumin using dopamine (DA) polymerization. Each single antigen was bound to its corresponding antibody to derive standard curves for Enro and Cip. The fiber-optic sensor's sensitivity was 2900 nm/RIU. Detection limits were calculated to be 1.20 ng/mL for Enro and 0.81 ng/mL for Cip. The actual system's recovery rate was obtained by testing Enro and Cip in milk samples; enrofloxacin's and ciprofloxacin's mean recoveries from the milk samples were 96.46-120.46% and 96.74-126.9%, respectively. In addition, several different regeneration solutions were tested to analyze the two target analytes' regeneration ability; NaOH and Gly-HCl solutions were found to have the best regeneration ability.

Graphitic-carbon-nitride-hydrophilicity-dependent photocatalytic degradation of antibiotics with different log Kow

The surface hydrophilicity of a photocatalyst is an important factor that directly influences its interactions with organic pollutants and significantly impacts its degradation. In this study, we investigated the impact of increased hydrophilicity of g-C3N4 (CN) by alkaline solvothermal treatment on the degradations of three antibiotics (oxytetracycline (OTC), oxolinic acid (OA), and sulfamethoxazole (SMX)) with different log Kow values. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and Fourier-transform infrared (FT-IR) spectroscopy showed no significant differences in the morphology, crystalline structure, and surface functional groups of CN after alkaline solvothermal treatment (Nv-HPCN). However, contact angle analysis revealed that Nv-HPCN (31.8°) was more hydrophilic than CN (61.1°). To assess the hydrophilicity of the antibiotics, the log Kow values of SMX (0.77), OA (0.43), and OTC (-0.34) were measured. Nv-HPCN showed faster OTC degradation than CN, whereas the opposite pattern was observed for the degradation of OA. Scavenger tests showed that O2•- and h+ mainly contributed to the degradation of these antibiotics. Furthermore, the influences of NOM and coexisting anions on antibiotic degradation were investigated. This study thus offers perspectives on the impact of surface hydrophilicity of photocatalysts on the degradation of antibiotics.

Triple-Emission Single Sensing Element-Enabled Ratiometric Fluorescent Array Identification of Multiple Antibiotics

Given that intricate toxicological profiles exist among different antibiotics and pose serious threats to the environment and human health, synchronous analysis of multiple residues becomes crucial. Sensor arrays show potential to achieve the above purpose, but it is challenging to develop easy-to-use and high-sensitivity tools because the state-of-the-art arrays often require more than one recognition unit and are monosignal dependent. Here we exquisitely designed a fluorescent nanoprobe (2-aminoterephthalic acid-anchored CdTe quantum dots with Eu3+ coordination, CdTe-ATPA-Eu3+) featuring triple emissions at the same excitation as the only element to fabricate a luminescent sensor array with ratiometric calculations for identifying multiple antibiotics. By taking tetracycline, chlortetracycline, doxycycline, oxytetracycline, penicillin G, and sulfamethoxazole as models, the six species exhibited distinguishable motivation or/and quenching impacts on the three emissions of CdTe-ATPA-Eu3+, which were employed as indicators to perform the ratiometric logical operation and further combined with pattern recognition analysis for multitarget determination. Evidently, such a design exhibits two advances: (1) with the triple-emission probe as the sole receptor requiring neither internal nor external adjustments, the fabricated array acts as an extremely facile tool for multianalyte detection; (2) the ratiometric calculations offer excellent sensitivity and reliability for high-performance determination. Consequently, accurate identification and quantification of individual antibiotics and their combinations at various levels were verified in both laboratory and practical matrices. Our work provides a new tool for simultaneously detecting multiple antibiotics, and it will inspire the development of advanced sensor arrays for multitarget analysis.