Antibiotic pollution in surface fresh waters: Occurrence and effects

Photodegradable Antimicrobial Agents: Synthesis and Mechanism of Degradation

As a strategy to inactivate antimicrobial agents after use, we designed a range of ethanolamine derivatives where four of them possessed interesting activity. The ethanolamine moiety facilitates photodecomposition, which in a potential drug will take place after use. Herein, the synthetic preparation of these compounds and the mechanism of photoinactivation are described.

Assessment of diphenhydramine toxicity - Is its mode of action conserved between human and zebrafish?

The main aim of the study is to evaluate the effects of the pharmaceutical diphenhydramine (DPH) on embryo-larvae Danio rerio across distinct levels of organization - individual and subcellular - and correlate those effects with the DPH mode of action (MoA) assessed by in silico analysis. An embryos heartbeat rate reduction was observed at 10 mg/L DPH, but 0.001 to 10 mg/L did not significantly affect the zebrafish survival, hatching and morphology. Larvae swimming distance decreased (hypoactivity) at 1 and 10 mg/L DPH. Moreover, the straightforward movements decrease and the increase in the zigzag movements or movements with direction changes, shown an erratic swimming behavior. Energy budgets decreased for lipid (0.01 mg/L DPH) and carbohydrate (10 mg/L DPH) contents. Cholinesterase (neural function) and glutathione S-transferase (Phase II biotransformation/antioxidant processes) increased their activities at 10 mg/L DPH, where a decrease in the total glutathione content (antioxidant system) was observed. DNA damage was found at 0.01 and 10 mg/L DPH. However, a DNA repair occurred after subsequent 72 h in clean media. The in silico study revealed a relevant conservation between human and zebrafish DPH target molecules. These data provide a valuable ecotoxicological information about the DPH effects and MoA to non-target organisms.

Preparation of a novel clay loaded with Fe (VI) for degradation of cefazolin: performance, pathway, and mechanism

Cephalosporin antibiotics, a group of widely prescribed antibiotics, are frequently detected in wastewater effluent and in the natural aquatic environment. Materials have been sought to effectively degrade the antibiotics. In this study, a novel high-iron clay was prepared with potassium ferrate and montmorillonite via a strong alkaline in situ synthesis method. Degradation of cefazolin sodium (CFZ) by this novel Fe (VI)-clay was investigated. The optimal conditions for the degradation of CFZ were determined using a single factor experiment and response surface optimization method. We found that 89.84% removal efficiency was obtained in 137 min when pH value was 5.16 and Fe (VI)-clay dosage was 0.79 g. The CFZ degradation mechanism was studied by computations on the Frontier Electron Density (FED) in combination with spectroscopic and mass spectroscopic analysis. The spectroscopic characteristics of the products at different stages showed that the oxidation decomposition reaction occurred during the degradation of CFZ by Fe (VI)-clay. Furthermore, FED calculation combined with GC-MS results showed that the degradation pathways of CFZ by the Fe (VI)-clay was mainly the cleavage of β-lactam, thiadiazole, tetrazole, and dihydrothiazine rings.

The investigation of influencing factors on the degradation of sulfonamide antibiotics in iron-impregnated biochar-activated urea-hydrogen peroxide system: A QSAR study

Iron-impregnated biochar-activated urea-hydrogen peroxide (FB-activated UHP) is a potential in-situ technology for simultaneously reducing soil sulfonamide antibiotic contaminants and improving soil fertility. To better understand the degradation of sulfonamide antibiotics by FB-activated UHP, a two-dimensional quantitative structure-activity relationship (2D-QSAR) model based on quantum chemical parameters and a three-dimensional QSAR (3D-QSAR) model based on molecular force field were developed to investigate the factors influencing the removal efficiencies (Re%). The optimal 2D-QSAR model was Re%= 0.858-8.930 E-5 E_B3LYP-0.175 f(+)_x with the evaluation indices of R²= 0.732, q²= 0.571, and Q_ext²= 0.673. The given 2D-QSAR model indicated that the molecular size (E_B3LYP) and Fukui index with respect to nucleophilic attack (f(+)) were intrinsic factors influencing Re%. Three degradation pathways were subsequently proposed based on the f(+) distribution. Compared to the 2D-QSAR model, the developed 3D-QSAR model exhibited a better predictive ability, with the evaluation indices of R²= 0.989, q²= 0.696, and SEE= 0.001. The analysis of field contribution rates suggested that electrostatic field (48.2%), hydrophobic field (25.3%), and hydrogen-bond acceptor field (12.7%) were the main factors influencing Re%. These findings generated critical information for evaluating the degradation mechanisms/rules and provided theoretical bases for initially estimating the Re% of sulfonamide antibiotics undergoing FB-activated UHP process.

Pharmaceutical Pollution in Aquatic Environments: A Concise Review of Environmental Impacts and Bioremediation Systems

The presence of emerging contaminants in the environment, such as pharmaceuticals, is a growing global concern. The excessive use of medication globally, together with the recalcitrance of pharmaceuticals in traditional wastewater treatment systems, has caused these compounds to present a severe environmental problem. In recent years, the increase in their availability, access and use of drugs has caused concentrations in water bodies to rise substantially. Considered as emerging contaminants, pharmaceuticals represent a challenge in the field of environmental remediation; therefore, alternative add-on systems for traditional wastewater treatment plants are continuously being developed to mitigate their impact and reduce their effects on the environment and human health. In this review, we describe the current status and impact of pharmaceutical compounds as emerging contaminants, focusing on their presence in water bodies, and analyzing the development of bioremediation systems, especially mycoremediation, for the removal of these pharmaceutical compounds with a special focus on fungal technologies.

Cadmium stress efficiently enhanced meropenem degradation by the meropenem- and cadmium-resistant strain Pseudomonas putida R51

The β-lactam antibiotic meropenem (MEM) is widely used in infectious disease treatment and consequently can be released into the environment, causing environmental pollution. In this study, Pseudomonas putida strain R51 was isolated from the wastewater of a poultry farm and found to efficiently degrade MEM. The genome of strain R51 contains a variety of heavy metal and antibiotic resistance genes, including the metallo-β-lactamase gene (JQN61_03315) and cadmium resistance gene cadA (JQN61_19995). Under cadmium stress, the degradation rate of MEM increased significantly in strain R51. Transcriptional analysis revealed that the expression of JQN61_03315 and cadA significantly increased under cadmium stress and that the expression of many genes associated with heavy metal and antibiotic resistance also changed significantly. Molecular docking analysis suggested that metallo-β-lactamase JQN61_03315 binds to MEM. In addition, no plasmid was found in strain R51, and no mobile genetic elements were found nearby JQN61_03315. In conclusion. we proposed that JQN61_03315 was responsible for the degradation of MEM, that the expression of this gene was induced under cadmium stress, and that strain R51 can be used for bioremediation of MEM without the risk for the transmission of the MEM resistance gene. These findings will have importance for studying the microbial degradation of MEM in the presence of heavy metal pollutants.

Transcriptomic Analysis of Hepatotoxicology of Adult Zebrafish (Danio rerio) Exposed to Environmentally Relevant Oxytetracycline

The extensive use of the broad-spectrum antibiotics like oxytetracycline (OTC) has become a serious environmental issue globally. OTC has profound negative effects on aquatic organisms including fishes. In this study, RNA-Seq analysis was employed to examine the possible molecular mechanism of hepatotoxicology in zebrafish induced by OTC exposure. Adult male zebrafish was exposed to 0, 5, 90, and 450 μg/L OTC for 3 weeks. The results showed the decrease in body weight and tail length but the increase in total length of zebrafish under OTC exposure in a dose-dependent way. In addition, severe histopathological damages were featured by increasing tissue vacuolization in the livers of 450 μg/L OTC group. Moreover, RNA-Seq analysis revealed that molecular signaling and functional pathways in the liver were disrupted by OTC exposure. Furthermore, the down-regulation of gene expression after OTC exposure was found on both the genes related to fatty acid degradation and the genes related to lipid synthesis. The present study implied that OTC induced liver malfunction and fish health risks through growth retard, histopathological damages, molecular signaling disruption, genetic expression alteration, and lipid metabolism disturbance.

Promoting effect of plant hormone gibberellin on co-metabolism of sulfamethoxazole by microalgae Chlorella pyrenoidosa

In this study, sodium acetate (NaAC) as a co-substrate effectively promoted the metabolism of sulfamethoxazole (SMX) by microalgae Chlorella pyrenoidosa. In the cultivation supplied with 5.0 and 10.0 g L^-1 NaAC, 51.1% and 61.2% SMX was removed, respectively. On this basis, the improvement effect of plant hormone gibberellin (GA₃) on SMX removal by 5 g L^-1 NaAC supplied as co-substrate was further investigated. The results showed that biodegradation played decisive role in the removal of SMX. As a plant hormone, GA₃ effectively improved the co-metabolic removal efficiency of SMX by C. pyrenoidosa. Especially when GA₃ dosage reached 10.0 and 50.0 mg L^-1, C. pyrenoidosa showed a very high SMX removal rate of 83.5% and 95.3%, respectively. Transcriptome analysis showed that GA₃ promoted the removal of SMX by C. pyrenoidosa was the result of the combined action of exogenous and endogenous plant hormones.

Engineering single-atom Fe-Pyridine N4 sites to boost peroxymonosulfate activation for antibiotic degradation in a wide pH range

Single-atom Fe catalysts have shown great potential for Fenton-like technology in organic pollutant decomposition. However, the underlying reaction pathway and the identification of Fe active sites capable of activating peroxymonosulfate (PMS) across a wide pH range remain unknown. We presented a novel strategy for deciphering the production of singlet oxygen (¹O₂) by regulating the Fe active sites in this study. Fe single atoms loaded on nitrogen-doped porous carbon (Fe_SA-CN) catalysts were synthesized using a cage encapsulation method and compared to Fe-nanoparticle-loaded catalysts. It was discovered that Fe_SA-CN catalysts served as efficient PMS activators for pollutant decomposition over a wide pH range. Several analytical measurements and density functional theory calculations revealed that the pyridinic N-ligated Fe single atom (Fe-pyridine N₄) was involved in the production of ¹O₂ by the binding of two PMS ions, resulting in an excellent catalytic performance for PMS adsorption/activation. This work has the potential to not only improve the understanding of nonradical reaction pathway but to also provide a generalizable method for producing highly stable PMS activators with high activity for practical wastewater treatment.

Exploring kinetics, removal mechanism and possible transformation products of tigecycline by Chlorella pyrenoidosa

The accumulation of antibiotics in wastewater leads to broad antibiotic resistance, threating human health. Microalgae have been receiving attention due to their ability to remove antibiotics from wastewater. Tigecycline (TGC) is a broad-spectrum glycylcycline antibiotic. It has not been investigated for removal by microalgae. The removal kinetics of TGC by Chlorella pyrenoidosa were evaluated under different initial dry cell densities, TGC concentrations, temperatures and light intensity conditions. Approximately 90% of TGC could be removed when the TGC concentration was 10 mg∙L^-1 and the initial dry cell density was more than 0.2 g∙L^-1. A low value of TGC per g dry cell weight ratio led to a high removal efficiency of TGC. The initial dry cell density of microalgae was also critical for the removal of TGC. A high initial dry cell density is better than a low initial dry cell density to remove TGC when the ratio of the TGC concentration to dry cell weight are the same at the beginning of the cultivation. The removal mechanisms were investigated. Photolysis was a slow process that did not lead to removal at the beginning. Adsorption, hydrolysis, photolysis and biodegradation by microalgae were the main contributors to the removal of TGC. TGC was easily hydrolyzed under high -temperature conditions. Three transformation products of TGC by microalgae were identified. The stability of TGC was evaluated in water and salt solutions of citric acid, K₂HPO₄·3H₂O and ferric ammonium citrate. TGC was stable in ultrapure water and citric acid solution. TGC was hydrolyzed in K₂HPO₄·3H₂O and ferric ammonium citrate solutions.

Two-step pyrolysis biochar derived from agro-waste for antibiotics removal: Mechanisms and stability

This study used acetone washing biochar (BCA) and nitric-acid washing biochar (BCN) derived from bagasse to remove sulfamethoxazole (SMX) and tetracycline (TC) in water. Higher specific surface area (1119.53 m² g^-1) and graphitization degree can significantly improve decontamination efficacy, of which BCN has the highest SMX and TC sorption capacities (274.63 mg g^-1 and 353.85 mg g^-1). The kinetics, isotherms and characterization analysis indicated O-containing functional group complexation and π-π interaction were dominant mechanisms in the adsorption process. Adsorption stability experiment showed that BCA has better stability with the coexistence of anions and cations. Besides, the enhancement and competitive adsorption from the interaction between soluble organic matter and TC could facilitate TC decontamination. Therefore, bagasse biochar derived from agro-waste has a promising potential for antibiotic contaminants removal from multi-interference conditions and promotes the recycling of waste, thereby achieving harmony between materials and the ecological environment.

Efficacy of Ciprofloxacin and Amoxicillin Removal and the Effect on the Biochemical Composition of Chlorella vulgaris

Antibiotics are frequently detected in the aquatic environment due to their excessive usage and low-efficiency removal in wastewater treatment plants. This can provide the origin to the development of antibiotic-resistant genes in the microbial community, with considerable ecotoxicity to the environment. Among the antibiotics, the occurrence of ciprofloxacin (CIP) and amoxicillin (AMX) has been detected in various water matrices at different concentrations around the Earth. They are designated as emerging contaminants (ECs). Microalga Chlorella vulgaris (C. vulgaris) has been extensively employed in phycoremediation studies for its acclimatization property, non-target organisms for antibiotics, and the production of value-added bioproducts utilizing the nutrients from the wastewater. In this study, C. vulgaris medium was spiked with 5 mg/L of CIP and AMX, and investigated for its growth-stimulating effects, antibiotic removal capabilities, and its effects on the biochemical composition of algal cells compared to the control medium for 7 days. The results demonstrated that C. vulgaris adapted the antibiotic spiked medium and removed CIP (37 ± 2%) and AMX (25 ± 3%), respectively. The operating mechanisms were bioadsorption, followed by bioaccumulation, and biodegradation, with an increase in cell density up to 46 ± 3% (CIP) and 36 ± 4% (AMX), compared to the control medium. Further investigations revealed that, in the CIP stress-induced algal medium, an increase in major photosynthetic pigment chlorophyll-a (30%) and biochemical composition (lipids (50%), carbohydrates (32%), and proteins (65%)) was observed, respectively, compared to the control medium. In the AMX stress-induced algal medium, increases in chlorophyll-a (22%), lipids (46%), carbohydrates (45%), and proteins (49%) production were observed compared to the control medium. Comparing the two different stress conditions and considering that CIP is more toxic than AMX, this study provided insights on the photosynthetic activity and biochemical composition of C. vulgaris during the stress conditions and the response of algae towards the specific antibiotic stress. The current study confirmed the ability of C. vulgaris to adapt, bioadsorb, bioaccumulate, and biodegrade emerging contaminants. Moreover, the results showed that C. vulgaris is not only able to remove CIP and AMX from the medium but also can increase the production of valuable biomass usable in the production of various bioproducts.

Long-Term Study of Antibiotic Presence in Ebro River Basin (Spain): Identification of the Emission Sources

Water monitoring is key to determining the presence of potentially hazardous substances related to urban activities and intensive farming. This research aimed to perform a long-term (four years) quantitative monitoring of selected antibiotics (azithromycin, enrofloxacin, trimethoprim and sulfadiazine) both in rivers and wastewaters belonging to the Ebro River basin (North of Spain). The target antibiotics were chosen on the basis of a preliminary multispecies screening. The analysis of the antibiotics was carried out by LC-MS/MS on wastewater-treatment plant (WWTP) effluent, effluents of a slaughterhouse and hospital, rivers downstream and upstream of these WWTPs, and rivers close to extensive farming areas. The ANOVA test was performed to study the significant differences between the points exposed to concrete emission sources and antibiotic concentration. The monitoring, carried out from 2018 to 2020, has been essential to illustrating the presence of the most abundant antibiotics that were detected in the Ebro River basin. Enrofloxacin has appeared in river waters in significant concentrations, especially near intensive farming, meanwhile azithromycin has been frequently detected in wastewaters.

Hydrothermal carbonation carbon-based photocatalysis under visible light: Modification for enhanced removal of organic pollutant and novel insight into the photocatalytic mechanism

Hydrothermal carbonation carbon (HTCC) is emerging as a promising alternative for photocatalytic removal of contaminants from water. However, the catalytic activity of HTCC is limited by its poor charge transfer ability, and its photocatalytic mechanism remains unclear. Herein, a unique photosensitization-like mechanism was firstly found on Fe modified HTCC (Fe-HTCC) derived from glucose for effective removal of organic pollutants. Under visible light illumination, the organic pollutant coordinated with Fe-HTCC enabled electrons transfer from its highest occupied molecular orbital (HOMO) to conduction band (CB) of Fe-HTCC, which not only oxidized pollutant itself, but also generated oxygen-centered radical for reducing O₂ into O₂^•- towards pollutant removal. The degradation kinetic constant of sulfamethoxazole (SMX) over Fe-HTCC was about 1024.4 and 20.5 times higher than that of HTCC and g-C₃N₄, respectively. The enhanced performance of Fe-HTCC was originated from dual role of Fe modification: one is to boost the electron-deficient C sites which prefer to coordinate with amino or hydroxyl of pollutants; the other is to enhance the linkage of discrete polyfuran chains in Fe-HTCC for effective electron transfer from pollutant to Fe-HTCC. This work provides new insight into the synthesis and mechanism of HTCC-based high-efficiency photocatalyst for water decontamination.

Insight into the role of different extracellular polymeric substances components on trimethoprim adsorption by activated sludge

Adsorption is the primary mechanism of antibiotic removal in wastewater treatment plants, wherein the extracellular polymeric substances (EPS) of the activated sludge play an important role. Due to their complex characteristics, the effect of EPS components on antibiotic adsorption is unknown. Therefore, in this study, the role of main components of EPS in antibiotic adsorption was explored using enzymatic treatment. The results revealed that proteinase K and α-amylase can efficiently hydrolyse the proteins and polysaccharides of EPS. The protein content of EPS reduced from 31.25 mg/g VSS to 21.53, 18.75, and 10.76 mg/g VSS, after treatment with proteinase K, α-amylase and their combination, respectively; the polysaccharides content also observed a similar decrease from 15.20 mg/g VSS to 8.22, 7.83, and 6.03 mg/g VSS, respectively. The humic substance in EPS was stable during enzymatic treatment. The equilibrium adsorption capacity of activated sludge treated by enzyme for trimethoprim (TMP)- a typical antibiotic, was significantly increased from 2.19 μg/g VSS to 4.68, 5.34, and 8.36 μg/g VSS after treatment with proteinase K, α-amylase and their mixture. The adsorption process was adequately described by pseudo-second-order kinetic model. A multivariable linear regression model was subsequently used to quantify the adsorption capacity of activated sludge for TMP considering the concentration of EPS components. The modelling and validated results showed that the model could satisfactorily predict the TMP adsorption capacity. The results of this study can provide new insights into the role of EPS on antibiotic transformation in biological wastewater treatment systems.

Multi-heteroatom-doped carbocatalyst as peroxymonosulfate and peroxydisulfate activator for water purification: A critical review

Catalytic activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) (or collectively known as persulfate, PS) using carbocatalyst is increasingly gaining attention as a promising technology for sustainable recalcitrant pollutant removal in water. Single heteroatom doping using either N, S, B or P is widely used to enhance the performance of the carbocatalyst for PS activation. However, the performance enhancement from single heteroatom doping is limited by the type of heteroatom used. To further enhance the performance of the carbocatalyst beyond the limit of single heteroatom doping, multi-heteroatom doping can be conducted. This review aims to provide a state-of-the-art overview on the development of multi-heteroatom-doped carbocatalyst for PS activation. The potential synergistic and antagonistic interactions of various heteroatoms including N and B, N and S, N and P, and N and halogen for PS activation are evaluated. Thereafter, the preparation strategies to develop multi-heteroatom-doped carbocatalyst including one-step and multi-step preparation approaches along with the characterization techniques are discussed. Evidence and summary of the performance of multi-heteroatom-doped carbocatalyst for various recalcitrant pollutants removal via PS activation are also provided. Finally, the prospects of employing multi-heteroatom-doped carbocatalyst including the need to study the correlation between different heteroatom combination, surface moiety type, and amount of dopant with the PS activation mechanism, identifying the best heteroatom combination, improving the durability of the carbocatalyst, evaluating the feasibility for full-scale application, developing low-cost multi-heteroatom-doped carbocatalyst, and assessing the environmental impact are also briefly discussed.

Fully-automated SPE coupled to UHPLC-MS/MS method for multiresidue analysis of 26 trace antibiotics in environmental waters: SPE optimization and method validation

Achieving simultaneous determination of antibiotic multiresidues in environmental waters by solid phase extraction (SPE) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with detection limits ≤ ng L^-1 is still a huge challenge. Moreover, the offline SPE procedure was performed manually, costly, and time-consuming, while the online SPE required precision pretreatment instruments that require highly-skilled personnel. In this paper, a fully automated SPE coupled with UHPLC-MS/MS method was developed for analysis of antibiotics (sulfonamides, quinolones, and macrolides) in water matrices. Sample preparation optimization included SPE materials and configuration (HLB disks), sample volume (500-1000 mL), and pH (pH = 3) with a flow rate at 2~5 mL min^-1, and an elution procedure with 2 × 6 mL methanol, and 2 × 6 mL acetone. Meanwhile, the parameters for UHPLC-MS/S detection of analytes were optimized, including LC retention time, and MS parameters. The instrumental limits of detection (LOD) and quantification (LOQ) of analytes ranged from 0.01-0.72 μg L^-1 and 0.05-2.39 μg L^-1, respectively, with satisfactory linear calibration (R² > 0.995) and precision (< 9.9%). Recoveries in spike samples ranged between 77.5-104.9% in pure water, 59.4-97.8% in surface water (SW), and 58.2-108.6% in wastewater effluent (WWE) with relative standard deviations ≤ 12.8%. The matrix effects observed for most analytes were suppression (0-28.1%) except for five analytes having presented enhancement (0-14.6 %) in SW or WWE. This method can basically meet the needs of trace antibiotic residues detection in waters, with examples of concentrations of detected antibiotics being lower than LOQ (LLQ) -94.47 ng L^-1 in WWEs and LLQ-15.47 ng L^-1 in SW in the lower reaches of the Yangtze River Basin.

Electrochemically activated peroxymonosulfate for the abatement of chloramphenicol in water: performance and mechanism

In this study, electrochemically activated peroxymonosulfate (EC/PMS) with a sacrificial iron electrode was used for the removal of chloramphenicol (CAP) from water. Compared to electrolysis alone, peroxymonosulfate (PMS) alone, and Fe2+/PMS, EC/PMS significantly enhanced the CAP degradation. Various parameters, such as the applied current, electrolyte concentration, and PMS dose, were investigated to optimize the process. In addition, acidic conditions facilitated the CAP degradation. The presence of Cl- slightly enhanced the CAP degradation, while both HCO3- and NO3- exhibited an inhibitory effect on the CAP degradation. The floccules were also analyzed after the reaction by XPS and XRD. Quenching experiments indicated that both sulfate radicals (SO4●-) and hydroxyl radicals (•OH) were responsible for the CAP degradation. In addition, the degradation products were identified by LC/TOF/MS, and the degradation pathways were proposed accordingly. These results indicated that EC/PMS is a promising treatment process for the remediation of water polluted by CAP.

Influences of anthropogenic activities on water quality in the Saigon River, Ho Chi Minh City

Water quality for the surface water along the Saigon River in Ho Chi Minh City was assessed for four groups of water samples collected at the agricultural, industrial, residential, and less impacted areas. A variety of parameters indicating water quality including physicochemical parameters, nutrients, heavy metals, and antibiotic residues were measured for both the rainy and dry seasons, two main tropical seasons in HCM City using the standard methods. The results showed that the river water in the rainy season was detected with significantly higher values of turbidity, BOD5, PO₄-P, NH₄-N, NO₃-N; and lower values of pH, temperature, conductivity, DO, salinity, Cu, Zn, As, Ni, Hg compared to that in the dry season. Sulfamethoxazole and trimethoprim were highly detected in the industrial areas compared to the agricultural and residential areas. Multivariate analyses suggested that the industrial and residential activities were more important contributors to the pollution of the Saigon River than the agricultural activities in HCM City.

One-step synthesis of natural montmorillonite/hematite composites with enhanced persulfate catalytic activity for sulfamethoxazole degradation: Efficiency, kinetics, and mechanism

Along with rapid development of sulfate radicals-based advanced oxidation process, efficient, alternatively eco-friendly and cost-effective catalyst is of uppermost priority. However, expensive chemicals are used as source of metal in most of these catalysts, and lose sight of the abundant natural mineral resources on immediate surroundings. In this work, montmorillonite and hematite, two of abundantly natural minerals were utilized to prepare a persulfate catalyst (TMH@M) for sulfamethoxazole (SMX) degradation. The results indicated more than 91% of SMX was removed within 60 min in TMH@M/PS system. The degradation efficiency of SMX of TMH@M/PS combined system was impacted by SMX concentration, PS dosage and natural organic matters, and can remain stable in a certain concentration of HA/chelating agent and a wide pH range (3.01-9.06). Radical scavenging and EPR tests demonstrated ¹O₂, OH, and SO₄^- were major reactive oxygen species in the TMH@M/PS system, while the latter seems more important for degradation of SMX. The results of SEM-EDS, XRD and XPS conformed that low valence iron species (Fe⁰, Fe²⁺ and Fe₃O₄) on TMH@M surface are the main driving force behind PS activation to generate reactive species. Furthermore, the iron species on TMH@M surface were transformed during reaction, that in favor of mitigating metal leaching. This work presented a method based on ubiquitous natural minerals to prepare catalyst with excellent PS activate performance for organic wastewater treatment implying a new strategy in minerals utilization deeply and a promisingly alternative process for organic wastewater treatment based on mineral materials.

Antimicrobial Resistance in Rivers: A Review of the Genes Detected and New Challenges

River ecosystems are very important parts of the water cycle and an excellent habitat, food, and drinking water source for many organisms, including humans. Antibiotics are emerging contaminants which can enter rivers from various sources. Several antibiotics and their related antibiotic resistance genes (ARGs) have been detected in these ecosystems by various research programs and could constitute a substantial problem. The presence of antibiotics and other resistance cofactors can boost the development of ARGs in the chromosomes or mobile genetic elements of natural bacteria in rivers. The ARGs in environmental bacteria can also be transferred to clinically important pathogens. However, antibiotics and their resistance genes are both not currently monitored by national or international authorities responsible for controlling the quality of water bodies. For example, they are not included in the contaminant list in the European Water Framework Directive or in the US list of Water-Quality Benchmarks for Contaminants. Although ARGs are naturally present in the environment, very few studies have focused on non-impacted rivers to assess the background ARG levels in rivers, which could provide some useful indications for future environmental regulation and legislation. The present study reviews the antibiotics and associated ARGs most commonly measured and detected in rivers, including the primary analysis tools used for their assessment. In addition, other factors that could enhance antibiotic resistance, such as the effects of chemical mixtures, the effects of climate change, and the potential effects of the coronavirus disease 2019 pandemic, are discussed. Environ Toxicol Chem 2022;41:687-714. © 2022 SETAC.

River Biofilms Microbiome and Resistome Responses to Wastewater Treatment Plant Effluents Containing Antibiotics

Continuous exposure to low concentrations of antibiotics (sub-minimal inhibitory concentration: sub-MIC) is thought to lead to the development of antimicrobial resistance (AMR) in the environmental microbiota. However, the relationship between antibiotic exposure and resistance selection in environmental bacterial communities is still poorly understood and unproven. Therefore, we measured the concentration of twenty antibiotics, resistome quality, and analyzed the taxonomic composition of microorganisms in river biofilms collected upstream (UPS) and downstream (DWS) (at the point of discharge) from the wastewater treatment plant (WWTP) of Poitiers (France). The results of statistical analysis showed that the antibiotic content, resistome, and microbiome composition in biofilms collected UPS were statistically different from that collected DWS. According to Procrustes analysis, microbial community composition and antibiotics content may be determinants of antibiotic resistance genes (ARGs) composition in samples collected DWS. However, network analysis showed that the occurrence and concentration of antibiotics measured in biofilms did not correlate with the occurrence and abundance of antibiotic resistance genes and mobile genetic elements. In addition, network analysis suggested patterns of co-occurrence between several ARGs and three classes of bacteria/algae: Bacteroidetes incertae sedis, Cyanobacteria/Chloroplast, and Nitrospira, in biofilm collected UPS. The absence of a direct effect of antibiotics on the selection of resistance genes in the collected samples suggests that the emergence of antibiotic resistance is probably not only due to the presence of antibiotics but is a more complex process involving the cumulative effect of the interaction between the bacterial communities (biotic) and the abiotic matrix. Nevertheless, this study confirms that WWTP is an important reservoir of various ARGs, and additional efforts and legislation with clearly defined concentration limits for antibiotics and resistance determinants in WWTP effluents are needed to prevent their spread and persistence in the environment.

Combined exposure to non-antibiotic pharmaceutics and antibiotics in the gut synergistically promote the development of multi-drug-resistance in Escherichia coli

The gut microbiota represents an important reservoir of antibiotic-resistant bacteria (ARB), which poses a significant threat to public health. However, little is known about the emergence of ARB in the gut after the combined exposure to antibiotics and non-antibiotic pharmaceutics. Here, Escherichia coli, a common opportunistic pathogen in the gut microbiota, was exposed to the antidepressant duloxetine (2.5 µg/L-25 mg/L) and/or chloramphenicol (6 µg/L-4 mg/L). The resistant strains were isolated to determine the minimum inhibition concentration (MIC) of 29 antibiotics. Then, genome-wide DNA sequencing, global transcriptomic sequencing, and real-time quantitative polymerase chain reaction were performed to quantify the synergy between duloxetine and chloramphenicol. Combined exposure synergistically increased the mutation frequency of chloramphenicol resistance by 2.45-9.01 fold compared with the independent exposure. A combination index reaching 187.7 indicated strong duloxetine and chloramphenicol synergy. The resultant mutants presented heritable enhanced resistance to 12 antibiotics and became ARB to eight antibiotics. Furthermore, combined exposure significantly increased the transcriptomic expression of acrA, acrB, and marA in E. coli, and generated a more robust oxidative stress response. Together with the occurrence of DNA mutations in marR in the mutants, stronger triggers to the AcrAB-TolC transport system and the MlaFEDB ABC transporter via reactive oxygen species (ROS)-induced mutagenesis, verified by gene knockout, contributed to the synergistic enhancement of antibiotic resistance in the combined exposure group. Regardless of whether their formation was induced by duloxetine, chloramphenicol, or their combination, the E. coli mutants showed 1.1-1.7-fold increases in the expression levels of acrA, acrB, acrZ, mdtE, and mdtF. This pattern indicated that the mutants shared the same resistance mechanisms against chloramphenicol, involving the improved efflux pumps AcrAB-TolC and mdtEF. Our findings demonstrated that antibiotics and non-antibiotic pharmaceutics synergistically accelerate the evolution of ARB and may enhance their spread.

Coupling suspect and non-target analytical methods for screening organic contaminants of concern in agricultural & urban impacted waters: Optimization and application

Long-term exposure of contaminants to emerging concern (CECs) may pose risks to human health and ecosystems, even at low concentrations. Rivers impacted by both agricultural and urban activities experience distinctive environmental pressures due to receiving wastewaters that contain complex organics and their transformation products (TPs). In this study, we developed a regional database composed of 1200 CECs of high concern in Guangxi (South China). Further, we optimized a comprehensive analytical method for simultaneously screening for CECs and their TPs. The optimized screening method was applied to surface waters sampled from 10 different cross sections of a river that is impacted by both agricultural and urban activities. The best results of method optimization were achieved when the screening detection limit (SDL) ranged from 0.05 to 2 ng L^-1, and over 90% of the analytes had acceptable recovery rates ranging between 64.7% and 95.6% (RSD < 11%). Of the 1200 CECs contained in the regional database, 168 were detected in at least one sampling site of the studied river via suspect screening, and among them, 36 contaminants were found at all sampling sites. Also, 58 additional contaminants and 39 TPs were tentatively identified via non-target screening, among which 4 TPs were reported for the first time in the aquatic environment. Triazine herbicides and their TPs were identified at most of the sampling sites, with ametryn and atrazine posing relatively high risks in the river ecosystems. Furthermore, 31 known analytes were selected as standards in order to confirm the combined screening method; one false positive occurred in the non-target screening method. According to these results, the suspect screening strategy provides valuable confirmation for the identification of a wide range of CECs in water, while non-target screening can provide a reference for researchers and supplement the regional database, particularly in the study of TPs.

Investigation on Mechanism of Tetracycline Removal from Wastewater by Sinusoidal Alternating Electro-Fenton Technique

Sinusoidal alternating electro-Fenton (SAEF) is a new type of advanced electrochemical oxidation technology for the treatment of refractory organic wastewater. In this research, the removal performance and degradation mechanism of tetracycline (TC) were investigated, and the optimal operation parameters were determined. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrometer (FTIR) were used to characterize the morphology, elemental composition, crystal structure, function groups of sludge produced by SAEF. UV-visible spectroscopy (UV) and liquid chromatograph-mass spectrometer (LC-MS/MS) were employed to determine the concentration of organic matter, middle products of decomposed organics in the SAEF process, respectively. The results showed that the removal rates of TC, chemical oxygen demand (COD), electric energy consumption (EEC) and the amount of produced sludge (Ws) are 94.87%, 82.42%, 1.383 kWh⋅m−3 and 0.1833 kg⋅m−3 by SAEF, respectively, under the optimal conditions (pH = 3.0, conductivity (κ) = 1075 μS⋅cm−1, current density (j) = 0.694 mA⋅cm−2, initial c (TC) = 100 mg·dm−3, c [30%H2O2] = 1.17 cm3⋅dm−3, frequency (f) = 50 Hz, t = 120 min). Compared with pure direct electro-Fenton (DEF) or sinusoidal alternating current coagulation (SACC), SAEF was a highly effective method with low-cost for the treatment of TC wastewater. It was found that the conjugated structure of TC was destroyed to generate intermediate products, and then most of them was gradually mineralized into inorganic materials in the SAEF process.

Easily biodegradable substrates are crucial for enhancing antibiotic risk reduction: Low-carbon discharging policies need to be more specified

Governments have formulated stricter wastewater treatment plant (WWTP) discharge standards to address water pollution; however, with the cost of aggravating the refractory of the discharges. These policies are not in line with the classic co-metabolism theory; thus, we evaluated the effects of an easily biodegradable substrate on the removal efficiency of antibiotics and antibiotic resistance genes (ARGs) in the receiving water. In this study, reactor with 8 d of hydraulic retention time (HRT) was constructed to simulate a receiving river, and several antibiotics (0.30 mg/L each) were continuously discharged to the reactor (tetracycline, ciprofloxacin, amoxicillin, chloramphenicol, and sulfamethoxazole). Sodium acetate (NaAc) was used as a representative easily biodegradable substrate, and treatment protocols with and without a co-substrate were compared. The attenuation of the antibiotics in the simulated river and the production and dissemination of ARGs were analyzed. The results showed that 50 mg/L NaAc activated non-specific enzymes (a log2-fold change of 3.1-8.8 compared with 0 mg/L NaAc). The removal rate of the antibiotics was increased by 4-32%, and the toxicity of the downstream water was reduced by 35%. The upregulation of antioxidant enzymes caused the intracellular reactive oxygen species (ROSs) decreased by up to 47%, inhibiting horizontal gene transfer and reducing mobile genetic element-mediated ARGs (mARGs) by 18-56%. Furthermore, NaAc also increased the alpha diversity of the microbial community by 5-15% (Shannon-Wiener Index) and reduced the abundance of human bacterial pathogens by 22-36%. In summary, easily biodegradable substrates in the receiving water are crucial for reducing antibiotic risk.

Amelioration of adsorptive efficacy by synergistic assemblage of functionalized graphene oxide with esterified cellulose nanofibers for mitigation of pharmaceutical waste

An effort has been undertaken for valorization of surplus biomass to synthesize sustainable and commercially competitive nanoadsorbents utilizing green synthetic strategies. This study encompasses a pioneering research on the comparative adsorption analysis of different modified forms of graphene oxide (GO) combined with functionalized cellulose nanofibers (CNF) derived from surplus biomass for elimination of noxious drug species from aqueous environment with a comprehensive study for evaluating the effect of loading percentage of functionalized GO. Characteristic assessments of the prepared nanocomposites were performed using FT-IR studies, powder XRD studies, FESEM analysis, EDS analysis and BET studies. The prepared nanohybrids were evaluated for their adsorptive performance for elimination of ciprofloxacin and ofloxacin and their performance was optimized in terms of adsorbent loading, pH and initial drug concentration. Further, investigation of adsorbent properties and the adsorption process was undertaken by studying different kinetic and isotherm models of adsorption. The adsorption potential of functionalized CNF was substantially ameliorated through its facile assemblage with functionalized GO. The experimental outcomes revealed that 20 wt% loading of carboxylated graphene oxide within the perforated surface of esterified cellulose nanofibres exhibited best adsorption performance with maximum removal capacity of 45.04 mg g^-1 and 85.30 mg g^-1 for ciprofloxacin and ofloxacin, respectively. The outstanding regenerability and reusability of nanocomposites present tremendous potential for development of inexpensive and sustainable sorbent materials for managing pharmaceutical pollution. Literature presents scarce data and insufficient number of reports which thoroughly compares the role of differently functionalized GO to potentiate the adsorptive performance of biomass based nanocellulose and its broad application prospects in wastewater remediation. This marks the novelty of the present investigation.

Activation of peracetic acid with zero-valent iron for tetracycline abatement: The role of Fe(II) complexation with tetracycline

Peracetic acid (PAA) is an excellent oxidant that can produce multiple carbon-centered radicals (R•C). A novel advanced oxidation process (AOP) that combines PAA and nanoscale zero-valent iron (i.e. nZVI/PAA) is constructed to evaluate its performance toward tetracycline (TC) abatement. The nZVI/PAA process shows excellent abatement efficacy for TC in the pH range of 3.5-7.5. The presence of humic acid, HPO₄^2- and HCO₃^- exerts inhibitory effects on TC abatement, while the presence of Cl^- displays negligible influence in the nZVI/PAA process. Nanoscale zero-valent iron (nZVI) exhibits excellent reusability with no apparent variation in crystallinity. CH₃C(O)OO• is the predominant active radical that contributes to TC abatement, in which leakage of Fe(II) from the nZVI surface is crucial for a radical generation. Due to the strong complexation tendency of TC towards Fe(II), the Fe(II)-TC complexes are formed, which significantly accelerates the PAA decomposition and TC abatement compared to free Fe(II). In addition, the degradation intermediates of TC are identified, and a possible degradation pathway is proposed. These results will be useful for the application of PAA-based AOPs in the treatment of water containing organic micropollutants.

Highly efficient removal of quinolones by using the easily reusable MOF derived-carbon

As anthropogenic antibiotics, quinolones, e.g., ofloxacin have adverse impacts on ecological systems and human heaths. The removal of quinolones is of great importance, and adsorption techniques have been widely used to remove this hazardous contaminant. However, a robust and easy-operating adsorbent is still emergently required due to the complex chemical structure of quinolones. In this study, we successfully synthesized the promising metallic carbons (MCs) containing carbon nanotubes and cobalt nanoparticles by carbonizing Zn/Co-ZIF at 900 °C. Three different molar ratios of Co and Zn were applied to optimize the adsorption capacity on ofloxacin (OFL). Results showed MC with molar ratio of Co and Zn at 3:1 (Co-CNT/NPC_3/1) achieved the maximal adsorption capacity to 118.3 mg g^-1. Its adsorption performance was satisfied in the pH range from 5 to 9 and ionic strengths at 0.01 M. The main mechanisms for these adsorptions were identified as electrostatic attraction, metal coordination and π-π EDA. Removal efficiencies of quinolones higher than 68 mg g^-1 indicated the strong feasibility of this adsorbent for wastewater treatments. The regeneration of Co-CNT/NPC_3/1 at 600 °C allowed its at least 4-time reusability and its magnetic property enabled external magnets to recycle it from real environments.

Surface imprinted polymer on a metal-organic framework for rapid and highly selective adsorption of sulfamethoxazole in environmental samples

The demand for the removal of pollutants in aqueous solution has triggered extensive studies to optimize the performance of adsorbents, but the adsorption rate and selectivity of adsorbents have been overlooked. Hierarchically ordered porous vinyl-functionalized UIO-66 was used as supporter to prepare a surface molecular imprinted polymer (MIP-IL@UIO-66). The UIO-66 with large specific surface area significantly increased the number of active site of polymer, and so the MIP-IL@UIO-66 can achieve the rapid and highly selective adsorption of sulfamethoxazole (SMZ) in water. The structure and morphology of MIP-IL@UIO-66 was examined using scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption isotherms, thermogravimetry, X-ray photoelectron spectroscopy, and X-ray powder diffraction. Results indicate that the presented MIP-IL@UIO-66 has an ultrafast equilibrium rate (equilibrium time, 10 min), large adsorption capability (maximum capacity, 284.66 mg g^-1), excellent adsorption selectivity (selectivity coefficient, 11.36), and good reusability (number of cycles, 5 times) via equilibrium adsorption experiments. Subsequently, as a novel solid phase extraction (SPE) adsorbent, the adsorption performance of SMZ onto MIP-IL@UIO-66 was better than that of a commercial SPE adsorbent. A MISPE column combined with high-performance liquid chromatography (HPLC) was presented to detect SMZ in water, soil, egg, and pork samples with recoveries of 91-106%. Hydrogen bonds, electrostatic and π-π interactions, and molecular memory were attributed to recognizing the SMZ of MIP-IL@UIO-66.

Kinetics and mechanism of synergistic adsorption and persulfate activation by N-doped porous carbon for antibiotics removals in single and binary solutions

Porous carbon serves as a green material for efficient wastewater purification by adsorption and advanced oxidation processes. However, a clear understanding of the simultaneous removal of multiple pollutants in water is still ambiguous. Herein, the synergistic effect of adsorption and peroxydisulfate (PS) activation on kinetics and mechanism of removing single and binary antibiotic pollutants, sulfamethoxazole (SMX) and ibuprofen (IBP), from water by biomass-derived N-doped porous carbon was investigated. Our findings suggest that adsorption contributed to efficient removals of SMX/IBP. Comparative quenching experiments and electrochemical analysis demonstrated that hydroxyl (•OH) and sulfate (SO₄^•-) radicals, as well as singlet oxygen (¹O₂) led to the catalytic degradation of SMX, while only ¹O₂ reacted for IBP oxidation. Superoxide ion (O₂^•-) radicals were not related to SMX/IBP degradation. Electron transfer pathway accounted for PS activation but was not involved in direct SMX/IBP oxidation. Only slight differences were found between the degradation kinetics of SMX and IBP in the binary and single SMX or IBP solutions. This arose from the non-selective effect of adsorption and ¹O₂ attack for SMX/IBP removal, and the weak selective oxidation process of SMX by •OH and SO₄^•-. This study provides a new viewpoint on the role of adsorption in catalysis and enriches the mechanistic study of multi-component antibiotic degradation.

Insight into the rapid elimination of low-concentration antibiotics from natural waters using tandem multilevel reactive electrochemical membranes: Role of direct electron transfer and hydroxyl radical oxidation

Herein, we reported a tandem multilevel reactive electrochemical membrane (REM) system was promising for the rapid and complete removal of trace antibiotics from natural waters. Results indicate that a four-stage REM module-in-series system achieved steady over 98% removal of model antibiotic norfloxacin (NOR, 100 μg·L^-1) from wastewater treatment plant final effluent and surface water with a residence time of 5.4 s, and the electric energy consumption was only around 0.007-0.011 kWh·m^-3. As for the oxidation mechanism, direct electron transfer (DET) oxidation process played an important role in NOR rapid oxidation, enabling the REM system to tolerate various ^•OH scavenges in natural waters, including natural organic matters, Cl^- and HCO₃^-, even at very high concentration levels. Meanwhile, ^•OH-mediated indirect oxidation process promotes the oxidation and mineralization of NOR. Although the DET-dominated oxidation mechanism makes the REM system cannot achieve the complete mineralization of NOR with residence times of few seconds, the antibacterial activity from NOR was completely eliminated. This REM system featured effective removal performance of trace contaminants with low energy cost and was tolerant to complex waster matrix, suggesting that it could be a powerful supplementary step for wastewater/water treatment.

Combined effects of heatwaves and micropollutants on freshwater ecosystems: Towards an integrated assessment of extreme events in multiple stressors research

Freshwater ecosystems are strongly influenced by weather extremes such as heatwaves (HWs), which are predicted to increase in frequency and magnitude in the future. In addition to these climate extremes, the freshwater realm is impacted by the exposure to various classes of chemicals emitted by anthropogenic activities. Currently, there is limited knowledge on how the combined exposure to HWs and chemicals affects the structure and functioning of freshwater ecosystems. Here, we review the available literature describing the single and combined effects of HWs and chemicals on different levels of biological organization, to obtain a holistic view of their potential interactive effects. We only found a few studies (13 out of the 61 studies included in this review) that investigated the biological effects of HWs in combination with chemical pollution. The reported interactive effects of HWs and chemicals varied largely not only within the different trophic levels but also depending on the studied endpoints for populations or individuals. Hence, owing also to the little number of studies available, no consistent interactive effects could be highlighted at any level of biological organization. Moreover, we found an imbalance towards single species and population experiments, with only five studies using a multitrophic approach. This results in a knowledge gap for relevant community and ecosystem level endpoints, which prevents the exploration of important indirect effects that can compromise food web stability. Moreover, this knowledge gap impairs the validity of chemical risk assessments and our ability to protect ecosystems. Finally, we highlight the urgency of integrating extreme events into multiple stressors studies and provide specific recommendations to guide further experimental research in this regard.

Biofilm and Small Colony Variants-An Update on Staphylococcus aureus Strategies toward Drug Resistance

Recently, the drawbacks arising from the overuse of antibiotics have drawn growing public attention. Among them, drug-resistance (DR) and even multidrug-resistance (MDR) pose significant challenges in clinical practice. As a representative of a DR or MDR pathogen, Staphylococcus aureus can cause diversity of infections related to different organs, and can survive or adapt to the diverse hostile environments by switching into other phenotypes, including biofilm and small colony variants (SCVs), with altered physiologic or metabolic characteristics. In this review, we briefly describe the development of the DR/MDR as well as the classical mechanisms (accumulation of the resistant genes). Moreover, we use multidimensional scaling analysis to evaluate the MDR relevant hotspots in the recent published reports. Furthermore, we mainly focus on the possible non-classical resistance mechanisms triggered by the two important alternative phenotypes of the S. aureus, biofilm and SCVs, which are fundamentally caused by the different global regulation of the S. aureus population, such as the main quorum-sensing (QS) and agr system and its coordinated regulated factors, such as the SarA family proteins and the alternative sigma factor σB (SigB). Both the biofilm and the SCVs are able to escape from the host immune response, and resist the therapeutic effects of antibiotics through the physical or the biological barriers, and become less sensitive to some antibiotics by the dormant state with the limited metabolisms.

ZnO Transducers for Photoluminescence-Based Biosensors: A Review

Zinc oxide (ZnO) is a wide bandgap semiconductor material that has been widely explored for countless applications, including in biosensing. Among its interesting properties, its remarkable photoluminescence (PL), which typically exhibits an intense signal at room temperature (RT), arises as an extremely appealing alternative transduction approach due to the high sensitivity of its surface properties, providing high sensitivity and selectivity to the sensors relying on luminescence output. Therefore, even though not widely explored, in recent years some studies have been devoted to the use of the PL features of ZnO as an optical transducer for detection and quantification of specific analytes. Hence, in the present paper, we revised the works that have been published in the last few years concerning the use of ZnO nanostructures as the transducer element in different types of PL-based biosensors, namely enzymatic and immunosensors, towards the detection of analytes relevant for health and environment, like antibiotics, glucose, bacteria, virus or even tumor biomarkers. A comprehensive discussion on the possible physical mechanisms that rule the optical sensing response is also provided, as well as a warning regarding the effect that the buffer solution may play on the sensing experiments, as it was seen that the use of phosphate-containing solutions significantly affects the stability of the ZnO nanostructures, which may conduct to misleading interpretations of the sensing results and unreliable conclusions.

Sensitivity of photoelctrocehmical aptasensor using spiral nanorods for detecting antiobiotic levels in experimental and real samples

Given increasing concern regarding antibiotic environmental contamination, there is immediate need to monitor antibiotic levels to effectively control pollution. In this study, we used a photoelectrochemical aptasensor based on TiO₂@MoS₂ spiral nanoarrays to detect chloramphenicol (CAP) in antibiotics. Nanoarrays were directly grown on fluorine-doped tin oxide (FTO) conductive glass with excellent biochemical stability, while aptamer-SH were immobilized by chemical binding on a synthetic TiO₂@MoS₂ nanoarray. Results show that the photocurrents were reduced in the presence of photoelectrochemistry associated with specific selection of aptamer for CAP. When the measurement of the fabricated nanomaterial chip was carried out using a three-electrode system, we found a highly specific and stable detection of chloramphenicol that ranged between 0.1 pM and 1 μM, with the detection limit of 0.1 pM. In addition, we obtained satisfactory results when real sample were used to validate the potential of photoelectrochemical (PEC) aptasensor for detecting chloramphenicol content in milk. Our results demonstrate that photoelectrochemical aptasensor is conducive to the development of less toxic multifunctional nanomaterials, making the biosensor more robust and environmentally friendly. Therefore, photoelectrochemical aptasensor can be widely applied in the field of environmental monitoring.

MOF-5 derived ZnO-C nanoparticles combined with α-MnO2 for efficient degradation of tetracycline under visible light

A multifunctional α-MnO2/ZnO-C (MZ) Z-scheme photocatalyst was synthesized by suit-growth of α-MnO2 on the surface of MOF-5 and pyrolysis of the organic components in a certain condition. The obtained photocatalysts...

A review of microwave-assisted advanced oxidation processes for wastewater treatment

Microwave (MW) technology has gained increasing interest in wastewater treatment due to its unique properties, such as fast and uniform heating, hot spots effect, and non-thermal effect. MW enhances the production of active radicals (e.g., OH, SO₄^-), which exerts a stronger integrated treatment effect in combination with advanced oxidation processes. Over the years, microwave-assisted advanced oxidation processes (MW-AOPs) have developed rapidly to degrade pollutants as innovative treatment approaches. This paper provides a detailed classification and a comprehensive review of MW-AOPs. The latest applications of MW in different advanced oxidation systems (oxidation systems, catalytic oxidation systems, and photochemical, electrochemical and sonochemical systems) are reviewed. The reaction parameters and performance of MW-AOPs in wastewater treatment are discussed, and the enhancement of pollutant degradation by MW is highlighted. In addition, the operating costs of MW-AOPs are evaluated. Some recommendations on MW-AOPs are made for future research. This review provides meaningful information on the potential development and evolution of MW-AOPs.

A review on the ecotoxicological effect of sulphonamides on aquatic organisms

Antibiotics are extensively used to treat human and animal diseases and are especially used in animal production to promote the growth performance of livestock and aquatic animals. Sulphonamides, as important drugs for aquatic animals, are often used in aquaculture to prevent and treat diseases. However, various antibiotics found in the aquatic environment exhibit varying degrees of toxicity to aquatic organisms. Antibiotics in wastewater produced in industrial and agricultural processes are not thoroughly removed by sewage treatment and are released into water, which results in varying degrees of pollution of the surrounding water environment, forcing people to pay attention towards the ecosystem. Several studies have investigated the impact of antibiotics on aquatic organisms in water environment; however, only a few studies have investigated the underlying mechanism. Antibiotics persisting in an aquatic environment for a long time can cause genotoxicity and histopathological changes in various aquatic organisms. Therefore, this paper reviews the sources of antibiotics in aquatic environment, the pollution status of sulfonamides in aquatic environment at home and abroad, and focuses on the research status of ecotoxicological effects of sulfonamides on aquatic organisms. Because there are not only antibiotic pollution, but also many other pollutants, such as heavy metals, micro plastics and other chemicals, it will be a challenge to determine the combined effects of antibiotics or other pollutants on aquatic organisms in future environmental toxicity studies.

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Sulphonamides are ubiquitously detected in the water environment.

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Sulfamethoxazole is one of the least efficient antibiotics removed in wastewater treatment plants.

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Interaction of sulphonamides with other antibiotics needs more attention.

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Multigeneration studies related to the water environment are needed.

Facile fabrication of electrospun g-C3N4/Bi12O17Cl2/poly(acrylonitrile-co-maleic acid) heterojunction nanofibers for boosting visible-light catalytic ofloxacin degradation

Electrospun g-C3N4/Bi12O17Cl2/poly(acrylonitrile-co-maleic acid) nanofibers were fabricated and applied for highly efficient removal of ofloxacin.

Environmental Biofilms as Reservoirs for Antimicrobial Resistance

Characterizing the response of microbial communities to a range of antibiotic concentrations is one of the strategies used to understand the impact of antibiotic resistance. Many studies have described the occurrence and prevalence of antibiotic resistance in microbial communities from reservoirs such as hospitals, sewage, and farm feedlots, where bacteria are often exposed to high and/or constant concentrations of antibiotics. Outside of these sources, antibiotics generally occur at lower, sub-minimum inhibitory concentrations (sub-MICs). The constant exposure to low concentrations of antibiotics may serve as a chemical "cue" that drives development of antibiotic resistance. Low concentrations of antibiotics have not yet been broadly described in reservoirs outside of the aforementioned environments, nor is the transfer and dissemination of antibiotic resistant bacteria and genes within natural microbial communities fully understood. This review will thus focus on low antibiotic-concentration environmental reservoirs and mechanisms that are important in the dissemination of antibiotic resistance to help identify key knowledge gaps concerning the environmental resistome.

The Effectiveness of MOFs for the Removal of Pharmaceuticals from Aquatic Environments: A Review Focused on Antibiotics Removal

There is an increasing level of various pollutants and their persistence in aquatic environments. The improper use of antibiotics and their inefficient metabolism in organisms result in their release into aquatic environments. Antibiotic abuse has led to hazardous effects on human health. Thereby, efficient removal of pharmaceuticals, particularly antibiotics, from wastewater and contaminated water bodies is greatly interested in international research communities. Metal-organic framework (MOF) materials, as a hybrid group of material containing metallic center and organic linkers, offer a porous structure that is highly efficient for removing different pollutants from contaminated water and wastewater streams. This article aims to review the recent advancement in using MOF-based adsorbents and catalysts for the removal of pharmaceuticals, especially antibiotics, from polluted water. Applying MOFs-based structures for removing antibiotics using photocatalytic removal and adsorptive removal techniques will be discussed and evaluated in this review paper. Various MOF-based materials such as functionalized MOFs, MOF-based composites, magnetic MOF-based composites, MOFs templated-metal oxide catalysts for removing pharmaceuticals, personal care products, and antibiotics from contaminated aqueous media are discussed. Furthermore, effective operational parameters on the adsorption, adsorption mechanisms, adsorption isotherms, and thermodynamic parameters are explained and discussed. Finally, in the concluding remarks, the challenges and future outlooks of using MOFs-based adsorbents and catalysts for removing antibiotics are summarized.

It More than Adds Up: Interaction of Antibiotic Mixing and Temperature

Use of antibiotics for the treatment and prevention of bacterial infections in humans, agri- and aquaculture as well as livestock rearing leads to antibiotic pollution of fresh water and these antibiotics have an impact on free-living bacteria. While we know which antibiotics are most common in natural environments such as rivers and streams, there is considerable uncertainty regarding antibiotics’ interactions with one another and the effect of abiotic factors such as temperature. Here, we used an experimental approach to explore the effects of antibiotic identity, concentration, mixing and water temperature on the growth of Pseudomonas fluorescens, a common, ubiquitous bacterium. We exposed P. fluorescens to the four antibiotics most commonly found in surface waters (ciprofloxacin, ofloxacin, sulfamethoxazole and sulfapyridine) and investigated antibiotic interactions for single and mixed treatments at different, field-realistic temperatures. We observed an overall dependence of antibiotic potency on temperature, as temperature increased efficacy of ciprofloxacin and ofloxacin with their EC₅₀ lowered by >75% with a 10 °C temperature increase. Further, we show that mixtures of ciprofloxacin and ofloxacin, despite both belonging to the fluoroquinolone class, exhibit low-temperature-dependent synergistic effects in inhibiting bacterial growth. These findings highlight the context dependency of antibiotic efficacy. They further suggest antibiotic-specific off-target effects that only affect the bacteria once they enter a certain temperature range. This has important implications as freshwater systems already contain multi-drug antibiotic cocktails and are changing temperature due to environmental warming. These factors will interact and affect aquatic food webs, and hence this creates an urgent need to adapt and improve laboratory testing conditions to closer reflect natural environments.