Antibiotics removal from aquaculture effluents by ozonation: chemical and toxicity descriptors

Unraveling the nexus: Microplastics, antibiotics, and ARGs interactions, threats and control in aquaculture - A review

In recent years, aquaculture has expanded rapidly to address food scarcity and provides high-quality aquatic products. However, this growth has led to the release of significant effluents, containing emerging contaminants like antibiotics, microplastics (MPs), and antibiotic resistance genes (ARGs). This study investigated the occurrence and interactions of these pollutants in aquaculture environment. Combined pollutants, such as MPs and coexisting adsorbents, were widespread and could include antibiotics, heavy metals, resistance genes, and pathogens. Elevated levels of chemical pollutants on MPs could lead to the emergence of resistance genes under selective pressure, facilitated by bacterial communities and horizontal gene transfer (HGT). MPs acted as vectors, transferring pollutants into the food web. Various technologies, including membrane technology, coagulation, and advanced oxidation, have been trialed for pollutants removal, each with its benefits and drawbacks. Future research should focus on ecologically friendly treatment technologies for emerging contaminants in aquaculture wastewater. This review provided insights into understanding and addressing newly developing toxins, aiming to develop integrated systems for effective aquaculture wastewater treatment.

From wastewater to clean water: Recent advances on the removal of metronidazole, ciprofloxacin, and sulfamethoxazole antibiotics from water through adsorption and advanced oxidation processes (AOPs)

Antibiotics released into water sources pose significant risks to both human health and the environment. This comprehensive review meticulously examines the ecotoxicological impacts of three prevalent antibiotics-ciprofloxacin, metronidazole, and sulfamethoxazole-on the ecosystems. Within this framework, our primary focus revolves around the key remediation technologies: adsorption and advanced oxidation processes (AOPs). In this context, an array of adsorbents is explored, spanning diverse classes such as biomass-derived biosorbents, graphene-based adsorbents, MXene-based adsorbents, silica gels, carbon nanotubes, carbon-based adsorbents, metal-organic frameworks (MOFs), carbon nanofibers, biochar, metal oxides, and nanocomposites. On the flip side, the review meticulously examines the main AOPs widely employed in water treatment. This includes a thorough analysis of ozonation (O3), the photo-Fenton process, UV/hydrogen peroxide (UV/H2O2), TiO2 photocatalysis, ozone/UV (O3/UV), radiation-induced AOPs, and sonolysis. Furthermore, the review provides in-depth insights into equilibrium isotherm and kinetic models as well as prospects and challenges inherent in these cutting-edge processes. By doing so, this review aims to empower readers with a profound understanding, enabling them to determine research gaps and pioneer innovative treatment methodologies for water contaminated with antibiotics.

Enhanced degradation and removal of ciprofloxacin and ofloxacin through advanced oxidation and adsorption processes using environmentally friendly modified carbon nanotubes

This study explores the utilization of adsorption and advanced oxidation processes for the degradation of ofloxacin (OFL) and ciprofloxacin (CIP) using a green functionalized carbon nanotube (MWCNT-OH/COOH-E) as adsorbent and catalyst material. The stability and catalytic activity of the solid material were proved by FT-IR and TG/DTG, which also helped to elucidate the reaction mechanisms. In adsorption kinetic studies, both antibiotics showed similar behavior, with an equilibrium at 30 min and 60% removal. The adsorption kinetic data of both antibiotics were well described by the pseudo-first-order (PFO) model. Different advanced oxidation processes (AOPs) were used, and the photolytic degradation was not satisfactory, whereas heterogeneous photocatalysis showed high degradation (⁓ 70%), both processes with 30 min of reaction. Nevertheless, ozonation and catalytic ozonation have resulted in the highest efficiencies, 90%, and 70%, respectively, after 30-min reaction. For AOP data modeling, the first-order model better described CIP and OFL in photocatalytic and ozonation process. Intermediates were detected by MS-MS analysis, such as P313, P330, and P277 for ciprofloxacin and P391 and P332 for ofloxacin. The toxicity test demonstrated that a lower acute toxicity was observed for the photocatalysis method samples, with only 3.1 and 1.5 TU for CIP and OFL, respectively, thus being a promising method for its degradation, due to its lower risk of inducing the proliferation of bacterial resistance in an aquatic environment. Ultimately, the analysis of MWCNT reusability showed good performance for 2 cycles and regeneration of MWCNT with ozone confirmed its effectiveness up to 3 cycles.

Machine-learning-driven optical immunosensor based on microspheres-encoded signal transduction for the rapid and multiplexed detection of antibiotics in milk

Antibiotic residues are the most common contaminants in milk and other related dairy products. Simultaneous, convenient, and stable detection of antibiotic residues in foods is vital to secure public health. Herein, we proposed an optical immunosensor with easily-functionalized polystyrene nanoparticles differing in size and quantity, and bearing multiplex signal probes for the simultaneous detection of multiple antibiotics through a simple one-step signal conversion reaction. After the integration of the machine-learning-based transcoding analysis, this sensor is suitable for multiplexed detection of antibiotics in a broad linear range from pg/mL to ng/mL within 30 min, with an overall accuracy of >99 %. Compared to the conventional standard chemiluminescence immunoassays, this immunosensor is suitable for the accurate quantification of multiple antibiotics in milk, with improved accuracy, reduced costs, and simplified procedure. This ensures its applications in food safety monitoring when simultaneous detection of multiple hazardous substances in food matrices is needed.

Carbon-based materials as efficient adsorbents for the removal of antibiotics: The real contributions of carbon edge sites

Disclosing the effect of edge defects in carbon-based materials on antibiotic removal remains a great challenge. In this study, carbon-based adsorbents (DC-s) with different degrees of edge defects were synthesized on a large scale via a direct calcination of sodium citrate (SC) and their adsorption performance to antibiotics were explored. The experimental results suggested that the edge defects of DC-s samples were the active sites for the adsorption of tetracycline (TC) and norfloxacin (NOR). The adsorption capacity of the optimal sample DC-900 for TC and NOR was 155.8 and 168.0 mg g-1, respectively. Density functional theory (DFT) calculations further revealed that zigzag edge defects rather than armchair edge defects were crucial to the excellent adsorption performance of DC-s samples for antibiotics, and the natures for the difference in the adsorption performance of the two edge defects for antibiotics were their different electronic structures. In addition, DC-900 also showed stable adsorption efficiency for antibiotics in the interferences, dynamic adsorption, and cycle experiments, suggesting its good environmental application potential. This study provides new insight into clarifying the natures of edge defects with carbon-based adsorbents for high-efficiency removal of antibiotics, which may guide the exploration of cost-effective carbon-based adsorbents.

Photocatalytic degradation performance of antibiotics by WO3/α-Fe2O3/zeolite type II heterojunction with core-shell structure

The accumulation of antibiotics in the environment can be harmful to human health, and research on their disposal technologies is of increasing interest. In this study, WO3/α-Fe2O3/zeolite (WFZ) type II heterojunction composites with core-shell structures were prepared by coupling WO3 semiconductors with visible-light photocatalytic activity with α-Fe2O3 via hydrothermal synthesis using zeolite as a carrier for the adsorption of synergistic photocatalytic degradation of antibiotics in wastewater. X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), specific surface, and porosity measurements were used to characterize the structure of WFZ type II heterojunction. The performance of WFZ heterojunction for the visible photocatalytic degradation of antibiotics (tetracycline hydrochloride (TCH), ciprofloxacin (CIP), and levofloxacin hydrochloride (LVF)) was investigated. Through four photocatalytic cycles, the catalyst exhibited excellent durability and stability. This was attributed to the core-shell structure and type II heterojunction promoting the effective separation of photogenerated carriers and the extended visible light response range, which resulted in the best photocatalytic activity of the catalyst under visible light irradiation. Radical trapping experiments showed that superoxide radicals (•O2-) and hydroxyl radical (•OH) were the main active species that played a major role in the photocatalytic degradation. These findings show that the synthesized WFZ type-II heterojunction can be used as a reliable visible-light-responsive photocatalyst for the treatment of antibiotics in wastewater.

Occurrence, removal, and risk assessment of emerging contaminants in aquatic products processing sewage treatment plants

Emerging contaminants (ECs) in aquatic environments have attracted attention due to their wide distribution and potential ecotoxicities. Sewage treatment plants (STPs) are proven to be the major source of ECs in the aquatic environment, while there remains insufficient understanding of the removal and risk assessment of ECs in STPs. Here, we clarified the degradation and risk impact of 13 ECs in two aquatic product processing sewage treatment plants (APPSTPs) along the southeast coast of China. The concentrations of ECs followed the order: endocrine-disrupting chemicals (1877.85-15,398.02 ng/L in influent, 3.37-44.47 ng/L in effluent) >  > sulfonamide antibiotics (SAs, 75.14-906.19 ng/L in influent, 1.14-15.33 ng/L in effluent) > pharmaceutical and personal care products (PPCPs, 44.47-589.93 ng/L in influent, 2.54-34.16 ng/L in effluent) ≈ fluoroquinolone antibiotic (54.76-434.83 ng/L in influent, 10.75-32.82 ng/L in effluent) > other antibiotics (16.21-51.96 ng/L in influent, 0.68-6.17 ng/L in effluent). Moreover, the concentrations of PPCPs (decreased by 55.33-87.65% in peak fishing season) and antibiotics (increased by 44.99% in peak fishing season) were affected by fishing activities. In particular, the sequencing batch reactor (SBR) process had a better removal effect than the anaerobic-anoxic-oxic (A2/O) process on the treatment of some contaminants (e.g., norfloxacin and nonylphenol). Risk evaluations of ECs demonstrated that nonylphenol and SAs were at high- and low-risk states, respectively. Overall, our results provide important information for the degradation treatment of ECs, which is essential for pollutant management policy formulation.

Residue Depletion Profile and Estimation of Withdrawal Period for Sulfadimethoxine and Ormetoprim in Edible Tissues of Nile Tilapia (Oreochromis sp.) on Medicated Feed

Sulfadimethoxine (SDM) and ormetoprim (OMP) are antimicrobials used in combination to treat bacterial infections in fish farming. The use of this drug combination is not yet regulated in some countries, such as Brazil. Due to the lack of regulated drugs for aquaculture in Brazil, this study investigated the residue depletion profile of SDM and OMP in Nile tilapia (Oreochromis sp.) after oral administration. Fish were treated with medicated feed containing a 5:1 ratio of SDM:OMP at the dose of 50 mg kg BW-1 for five consecutive days with an average water temperature of 28 °C. The drugs were incorporated into the feed by using a gelatin coating process which promoted homogeneity in drug concentration and prevented the drug leaching into the water during medication. The SDM and OMP determination in fish fillets (muscle plus skin in natural proportions) was performed using the QuEChERS approach followed by LC-MS/MS quantification. The analytical method was validated according to Brazilian and selected international guidelines. A withdrawal period of 9 days (or 252 °C days) was estimated for the sum of SDM and OMP residues at concentration levels below the maximum residue level of 100 µg kg-1.

Visible-light-driven photocatalytic degradation of tetracycline hydrochloride by Z-scheme Ag3PO4/1T@2H-MoS2 heterojunction: Degradation mechanism, toxicity assessment, and potential applications

Residual antibiotics in wastewater threaten living organisms and the ecosystem, while the photocatalytic process is recognized as one of the most eco-friendly and promising technologies for the treatment of antibiotic wastewater. In this study, a novel Z-scheme Ag₃PO₄/1T@2H-MoS₂ heterojunction was synthesized, characterized, and used for the visible-light-driven photocatalytic degradation of tetracycline hydrochloride (TCH). It was found that Ag₃PO₄/1T@2H-MoS₂ dosage and coexisting anions had significant effects on the degradation efficiency, which could reach up to 98.9 % within 10 min under the optimal condition. Combing experiments and theoretical calculations, the degradation pathway and mechanism were thoroughly investigated. The excellent photocatalytic property of Ag₃PO₄/1T@2H-MoS₂ was achieved attributed to the Z-scheme heterojunction structure, which remarkably inhibited the recombination of photoinduced electrons and holes. The potential toxicity and mutagenicity for TCH and generated intermediates were evaluated, which revealed the ecological toxicity of antibiotic wastewater was reduced effectively during the photocatalytic degradation process.

Spatial confinement: A green pathway to promote the oxidation processes for organic pollutants removal from water

Organic pollutants removal from water is pressing owing to the great demand for clean water. Oxidation processes (OPs) are the commonly used method. However, the efficiency of most OPs is limited owing to the poor mass transfer process. Spatial confinement is a burgeoning way to solve this limitation by use of nanoreactor. Spatial confinement in OPs would (i) alter the transport characteristics of protons and charges; (ii) bring about molecular orientation and rearrangement; (iii) cause the dynamic redistribution of active sites in catalyst and reduce the entropic barrier that is high in unconfined space. So far, spatial confinement has been utilized for various OPs, such as Fenton, persulfate, and photocatalytic oxidation. A comprehensive summary and discussion on the fundamental mechanisms of spatial confinement mediated OPs is needed. Herein, the application, performance and mechanisms of spatial confinement mediated OPs are overviewed firstly. Subsequently, the features of spatial confinement and their effects on OPs are discussed in detail. Furthermore, environmental influences (including environmental pH, organic matter and inorganic ions) are studied with analyzing their intrinsic connection with the features of spatial confinement in OPs. Lastly, challenges and future development direction of spatial confinement mediated OPs are proposed.

Molecularly Imprinted Magnetic Nanocomposite Based on Carboxymethyl Dextrin for Removal of Ciprofloxacin Antibiotic from Contaminated Water

Broad-spectrum antibiotics from the fluoroquinolone family have emerged as prominent water contaminants, among other pharmaceutical pollutants. In the present study, an antibacterial magnetic molecularly imprinted polymer (MMIP) composite was successfully fabricated using carboxy methyl dextrin grafted to poly(aniline-co-meta-phenylenediamine) in the presence of Fe₃O₄/CuO nanoparticles and ciprofloxacin antibiotic. The characteristics of obtained materials were investigated using FTIR, XRD, VSM, TGA, EDX, FE-SEM, zeta potential, and BETanalyses. Afterward, the MMIP's antibacterial activity and adsorption effectiveness for removing ciprofloxacin from aqueous solutions were explored. The results of the antibacterial tests showed that MMIP had an antibacterial effect against Escherichia coli, a Gram-negative pathogen (16 mm), and Staphylococcus aureus, a Gram-positive pathogen (22 mm). Adsorption efficacy was evaluated under a variety of experimental conditions, including solution pH, adsorbent dosage, contact time, and initial concentration. The maximum adsorption capacity (Q_max) of the MMIP for ciprofloxacin was determined to be 1111.1 mg/g using 3 mg of MMIP, with an initial concentration of 400 mg/L of ciprofloxacin at pH 7, within 15 min, and agitated at 25 °C, and the experimental adsorption results were well-described by the Freundlich isotherm model. The adsorption kinetic data were well represented by the pseudo-second-order model. Electrostatic interaction, cation exchange, π-π interactions, and hydrogen bonding were mostly able to adsorb the majority of the ciprofloxacin onto the MMIP. Adsorption-desorption experiments revealed that the MMIP could be retrieved and reused with no noticeable reduction in adsorption efficacy after three consecutive cycles.

Efficient photocatalytic remediation of typical antibiotics in water via Mn3O4 decorated carbon nitride nanotube

Antibiotic abuse will seriously affect the ecology and environment. Photocatalytic oxidation technology based on carbon nitride (g-C₃N₄) has been widely adopted to treat wastewater containing antibiotics. Here, a novel composite photocatalyst MCNT was prepared by loading manganese oxide (Mn₃O₄) on the surface of g-C₃N₄ nanotubes (CNT). Three typical antibiotics, trimethoprim (TMP), norfloxacin (NOR), and tetracycline (TC) were used as model contaminants to evaluate the oxidative properties of prepared materials. Compared with bulk g-C₃N₄, the degradation rates of TMP, NOR, and TC catalyzed by MCNT-5 were increased by 2, 3, and 1.4 times, respectively, mainly due to 1) the larger specific surface area of the nanotube structure of CNT, which provides abundant active sites for antibiotic adsorption and catalytic oxidation, and 2) the loading of Mn₃O₄, which promotes the directional migration of photogenerated charges and improves the separation efficiency of photogenerated electrons and holes. The free radical capture and quenching experiments confirmed that MCNT degraded the target organic pollutants with hydroxyl radical (·OH) and singlet oxygen (¹O₂) as the main active oxidants. This catalyst maintained 80% photocatalytic oxidation performance after five cyclic experiments. This study provides new insights into developing efficient, stable, and environmentally-friendly photocatalysts and provides a new dimension to mitigate the antibiotic pollution problem.

Enhanced removal of organic contaminants by novel iron-carbon and premagnetization: Performance and enhancement mechanism

Iron-carbon (Fe-C) microelectrolysis has attracted considerable attention in wastewater treatment due to its excellent ability to remove contaminants. Herein, novel Fe-C granules were synthesized by simple calcination method for removing organic contaminations, and a cost-effective and environmentally friendly method, namely pre-magnetization, was used to improve the micro-electrolysis performance of Fe-C. Batch experiments proved that premagnetized iron-carbon (pre-Fe-C) could significantly improve the removal of methyl orange (MO) at different Fe-C mass ratios (1:2-2:1), material dosages (1.0-2.5 g/L), initial pH values (3.0-5.0), and MO concentrations (10.0-50.0 mg/L). Electrochemical analysis showed that premagnetization could increase the current density and reduce the charge transfer resistance of the microelectrolysis system, making Fe-C more susceptible to electrochemical corrosion. Characterizations confirmed that the corrosion products of the materials included FeO, Fe₂O₃, and Fe₃O₄, and more corrosion products were formed in the pre-Fe-C system. Radical quenching experiments and electron spin resonance spectroscopy verified that ^•OH, ¹O₂, and O₂^-• were all involved in pollutant removal, and premagnetization could promote the generation of more reactive oxygen species. Overall, the pre-Fe-C process could effectively remove various organic pollutants, exhibit good adaptability to complex water environments, and hold potential for industrial applications.