Tetracycline Removal Efficiency Research Articles

Removal of Cu(II) and tetracycline using an aromatic rings-functionalized chitosan-based flocculant: Enhanced interaction between the flocculant and the antibiotic

Weak interaction between flocculants and antibiotics is a limitation in the flocculation of combined contaminants of heavy metals and antibiotics. To solve this problem, a novel chitosan-based flocculant (BDAT-CTS) owning functional groups of aromatic rings, which possessed potential to interact with other aromatic rings in antibiotics, was synthesized and applied to remove Cu(II) and tetracycline (TC) from water. Effects of pH, flocculant dosage and initial contaminant concentration were studied in detail. In comparison with previous reported chitosan-based flocculant without aromatic rings structure, BDAT-CTS enjoyed significantly enhanced removal efficiency in the treatment of binary contaminants. The highest removal efficiencies of TC and Cu(II) could reach to 98.8% and 94.0%, respectively, under the corresponding optimal conditions. The improved performance was attributed to the strong triangle pairwise interactions among BDAT-CTS, Cu(II) and TC according to flocculation mechanism investigation: besides charge attraction and coordination of BDAT-CTS–Cu(II), and coordination of Cu(II)–TC, there also exists π–π stacking between the triazine rings in BDAT-CTS and the aromatic rings in TC. The current work provided valuable guidance in the design of eco-friendly polymeric flocculants in the treatment of combined water contamination of heavy metals and antibiotics.

Optimization of an A2/O process for tetracycline removal via response surface methodology coupled with a Box–Behnken design

Response surface methodology (RSM) was used to optimize the operating conditions of an anaerobic-anoxic-oxic (A2/O) process by maximizing the removal efficiency of tetracycline (TC). Solid retention time (SRT), hydraulic retention time (HRT) and initial TC concentration (CTC, in) were selected as independent variables for incorporation in the Box–Behnken design. The results showed SRT and CTC, in were more significant parameters than HRT for the removal efficiency of TC. TC could be completely removed under the optimal conditions of an SRT of 15.5 days, an HRT of 9.9 h and a CTC, in of 283.3 μg L−1. TC removal efficiencies of 99% and 96% were attained for synthetic and real wastewater, respectively, under the optimal conditions. This indicated the constructed model was validated and reliable for optimizing the A2/O process for TC removal.

Rapid Removal of Tetracycline (TC) by Ozonation after Extraction TC from Water into Acetic Acid Solution Using Granular Activated Carbon

This study quantifies the rapid removal of tetracycline (TC) in acetic acid solution by ozonation after extraction from water into acetic acid solution using granular activated carbon (GAC). Systematic laboratory experiments show that GAC can be used as an adsorbent to transfer TC from water to acetic acid. Ozone gas has a high degree of stability and solubility in acetic acid, and therefore apparently enhances the removal rate of TC. TC removal efficiency is better in 10% acetic acid solution than that in water, 15% and 20% acetic acid solution. Removal rate of TC in the acetic acid solution decreases as the initial molar ratio of TC and O3 increases. Inhibition effect of tertiary butyl alcohol (TBA) on TC removal is smaller in acetic acid than that in water. metal-TC complex was produced in the presence of Fe3+ and Co3+, which inhibited the degradation of TC by ozone in acetic acid. Removal of TC by ozone in the acetic acid solution might be affected by multiple factors, which should be considered in practical applications.

Adsorption of tetracycline onto alumina: experimental research and molecular dynamics simulation

Adsorption characteristics of tetracycline (TC) onto alumina were investigated according to batch adsorption experiments, and the mechanism was dissected at molecular level by molecular dynamics (MD) simulation. Results indicated that the adsorption was influenced by alumina dosage, temperature, and oscillating frequency. The optimal temperature was 25°C. By increasing the alumina dosage from 0.1 to 2.0 g/L, the removal efficiency of TC increased from 53.73 to 86.44%. With the increase in oscillation frequency from 90 to 200 r/min, the removal efficiency of TC increased by 28.78%, indicating that the increase of frequency could enhance the adsorption of TC. The adsorption behavior fitted well with the pseudo-second-order model (R2 > 0.99). MD simulations revealed that TC molecule structure was deformed when it clung to the alumina crystal. The magnitude of deformation energy (99.893 kcal/mol) was far less than that of non-bond energy (319,643.811 kcal/mol). Analysis of radial distribution function showed that TC could be adsorbed effectively by alumina mainly through non-bond interaction.

Removal of tetracycline from aqueous solution by a Fe3O4 incorporated PAN electrospun nanofiber mat

Pollution of antibiotics, a type of emerging contaminant, has become an issue of concern, due to their overuse in human and veterinary application, persistence in environment and great potential risk to human and animal health even at trace level. In this work, a novel adsorbent, Fe3O4 incorporated polyacrylonitrile nanofiber mat (Fe-NFM), was successfully fabricated via electrospinning and solvothermal method, targeting to remove tetracycline (TC), a typical class of antibiotics, from aqueous solution. Field emission scanning electron microscopy and X-ray diffraction spectroscopy were used to characterize the surface morphology and crystal structure of the Fe-NFM, and demonstrated that Fe-NFM was composed of continuous, randomly distributed uniform nanofibers with surface coating of Fe3O4 nanoparticles. A series of adsorption experiments were carried out to evaluate the removal efficiency of TC by the Fe-NFM. The pseudo-second-order kinetics model fitted better with the experimental data. The highest adsorption capacity was observed at initial solution pH4 while relative high adsorption performance was obtained from initial solution pH4 to 10. The adsorption of TC on Fe-NFM was a combination effect of both electrostatic interaction and complexation between TC and Fe-NFM. Freundlich isotherm model could better describe the adsorption isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was 315.31mg/g. Compared to conventional nanoparticle adsorbents which have difficulties in downstream separation, the novel nanofiber mat can be simply installed as a modular compartment and easily separated from the aqueous medium, promising its huge potential in drinking and wastewater treatment for micro-pollutant removal.

Synergistic Removal of Copper(II) and Tetracycline from Water Using an Environmentally Friendly Chitosan-Based Flocculant

In the current work, an environmentally friendly chitosan-based flocculant (carboxyethyl chitosan, denoted as CEC) was prepared to flocculate copper(II) and tetracycline (TC) simultaneously for the first time. The effects of flocculant dosage, pH, and initial contaminant concentration were systematically studied. For a single contaminant system, CEC demonstrates the desired flocculation performance for copper(II) removal, whereas its TC removal efficiency is poor. However, it is notable to find that the removal of TC can be significantly enhanced when copper(II) coexists in the binary contaminant system. Compared to the commercial flocculants polyaluminum chloride and polyacrylamide, CEC enjoys the advantages of lower dosage requirement, higher removal efficiency, and better floc properties. The flocculation mechanism was investigated via pH monitoring, zeta potential, and floc property measurements. The results indicate that charge neutralization predominates for single contaminant copper(II) removal, while for binary contaminant removal, TC can be embedded in copper(II) hydroxides through coordination with the metal, and finally synergistically eliminated with copper(II). This work gives a new approach to treating livestock wastewater and extends the application fields of flocculation.

Influence of tetracycline on the microbial community composition and activity of nitrifying biofilms

The present work aims to evaluate the bacterial composition and activity (carbon and nitrogen removal) of nitrifying biofilms exposed to 50μgL−1 of tetracycline. The tetracycline removal efficiency and the occurrence of tetracycline resistance (tet) genes were also studied. Two sequencing batch biofilm reactors (SBBRs) fed with synthetic wastewater were operated without (SBBR1) and with (SBBR2) the antibiotic. Both SBBRs showed similar organic matter biodegradation and nitrification activity. Tetracycline removal was about 28% and biodegradation was probably the principal removal mechanism of the antibiotic. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis of the bacterial community showed shifts leading to not only the fading of some ribotypes, but also the emergence of new ones in the biofilm with tetracycline. The study of the tet genes showed that tet(S) was only detected in the biofilm with tetracycline, suggesting a relationship between its occurrence and the presence of the antibiotic.

Fabrication of a three-dimensional BiOBr/BiOI photocatalyst with enhanced visible light photocatalytic performance

Three-dimensional (3D) BiOBr/BiOI hierarchical microsphere photocatalysts were successfully synthesized via a facile one-pot solvothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and N2 adsorption–desorption isotherms. The photocatalytic activity was evaluated by the photocatalytic degradation of Rhodamine B (RhB) and tetracycline (TC) under visible light irradiation (λ>420nm). The 50% BiOBr/BiOI composite showed a higher photocatalytic removal efficiency of RhB and TC than 10% and 90% BiOBr/BiOI composites. RhB (C0=15mg/L) was degraded completely within 40min and over 83% of TC (C0= 40mg/L) was degraded within 50min using a catalyst quantity of 0.4g/L of 50% BiOBr/BiOI. The enhanced photocatalytic activity of the 50:50 composite was attributed to effective separation of photogenerated carriers and the balance between enhanced visible light absorption and decreased valence band (VB) edge potential.

Degradation of Tetracycline by Birnessite under Microwave Irradiation

The efficiency and factors affecting tetracycline (TC) degradation by birnessite under microwave irradiation (MI) were investigated under different initial TC concentrations, solution pH, MI time, and MI power. The crystal structure, degradation efficiency, and reaction mechanism were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible spectroscopy (UV-Vis). The results showed that birnessite was an excellent microwave catalyst. The maximum TC removal efficiency by birnessite was 99% under MI at 400 W for 30 min in strongly acidic media. Under MI, the surface activity of birnessite increased, resulting in the ability to accelerate TC removal in high temperature.

Removal of tetracycline and oxytetracycline by microscale zerovalent iron and formation of transformation products

The main objective of this study was to determine the removal mechanism of tetracycline (TC) and oxytetracycline (OTC) by microscale zerovalent iron (mZVI) and the formation of transformation products during their removal studies. Solution pH, iron dose, and reaction temperature were studied with a batch experimental series in order to evaluate the removal efficiency of TC and OTC and the adsorption kinetics. The results showed that pH was a key factor in removing both tetracycline compounds, although increasing the temperature and iron dose enhanced their removal efficiency. The optimal pH was similarly found as 3 for both tetracycline and oxytetracycline. The kinetics of adsorption fitted the pseudo-second-order model perfectly. The adsorption data was interpreted by the Langmuir model with the maximum adsorption capacity of 23.98 and 34.01 mg g(-1) (60 °C) of TC and OTC on mZVI, respectively. The main transformation product was 4-epi-tetracycline for TC which quickly sorbed onto mZVI within 15 min. β-Apo-OTC and α-Apo-OTC were found as OTC transformation products. The removal mechanism of TC and OTC using mZVI surface was due to the adsorption rather than the degradation process.

Reduction of antibiotics using microorganisms containing glutathione S-transferases under immobilized conditions

The degradation of several antibiotics (tetracycline, sulfathiazole, ampicillin) was performed with immobilized bacterial cells containing the glutathione S-transferases (GSTs). Antibiotics in animal feed contaminated wastewater usually inhibit the growth of microorganisms that treat the wastewater, so a bio-friendly treatment method is required. Therefore, we have shown that the inhibitory effects of antibiotics on bacteria were reduced by microorganisms containing detoxifying enzyme GSTs by using a cell immobilizing method in a bioreactor. The initial concentrations of tetracycline, sulfathiazole and ampicillin were 100mg/L, 100mg/L and 50mg/L respectively, which are typical of the range detected in pig feed in Korea. In the results, we observed the removal efficiency of tetracycline to be almost 70% with Staphylococcus epidermidis in the bioreactor, suggesting that this method of antibiotic removal is worthy of further study.

Occurrence of pharmaceuticals in a municipal wastewater treatment plant: Mass balance and removal processes

Occurrence and removal efficiencies of fifteen pharmaceuticals were investigated in a conventional municipal wastewater treatment plant in Michigan. Concentrations of these pharmaceuticals were determined in both wastewater and sludge phases by a high-performance liquid chromatograph coupled to a tandem mass spectrometer. Detailed mass balance analysis was conducted during the whole treatment process to evaluate the contributing processes for pharmaceutical removal. Among the pharmaceuticals studied, demeclocycline, sulfamerazine, erythromycin and tylosin were not detected in the wastewater treatment plant influent. Other target pharmaceuticals detected in wastewater were also found in the corresponding sludge phase. The removal efficiencies of chlortetracycline, tetracycline, sulfamerazine, acetaminophen and caffeine were >99%, while doxycycline, oxytetracycline, sulfadiazine and lincomycin exhibited relatively lower removal efficiencies (e.g., <50%). For sulfamethoxazole, the removal efficiency was approximately 90%. Carbamazepine manifested a net increase of mass, i.e. 41% more than the input from the influent. Based on the mass balance analysis, biotransformation is believed to be the predominant process responsible for the removal of pharmaceuticals (22% to 99%), whereas contribution of sorption to sludge was relatively insignificant (7%) for the investigated pharmaceuticals.

Application of response surface methodology to the removal of the antibiotic tetracycline by electrochemical process using carbon-felt cathode and DSA (Ti/RuO2–IrO2) anode

The removal of antibiotic tetracycline (TC) from water by electrochemical advanced oxidation process (EAOP) was performed using a carbon-felt cathode and a DSA (Ti/RuO2–IrO2) anode. The influence of applied current, initial pH and initial TC concentration on TC removal efficiency was investigated. Response surface methodology (RSM) based on Box-Behnken statistical experiment design (BBD) was applied to analyze the experimental variables. The positive and negative effects of variables and the interaction between variables on TC removal efficiency were determined. The applied current showed positive effect, while the initial pH value and initial tetracycline concentration gave negative effect on TC removal. The interaction between applied current and initial pH value was significant, while the interactions of initial TC concentration with applied current or initial pH were not pronounced. The results of adequacy check confirmed that the proposed models were accurate and reliable to analyze the variables of EAOP. The reaction intermediates were identified by high-performance liquid chromatography–mass spectrometry (LC–MS) technique and a plausible degradation pathway for tetracycline degradation was proposed. The acute toxicity experiments illustrated that the Daphnia magna immobilization rate reached the maximum after 240min of electrolysis and then decreased with the progress of the reaction.

Removal of Antibiotics in Wastewater: Effect of Hydraulic and Solid Retention Times on the Fate of Tetracycline in the Activated Sludge Process

A study was conducted to examine the influence of hydraulic retention time (HRT) and solid retention time (SRT) on the removal of tetracycline in the activated sludge processes. Two lab-scale sequencing batch reactors (SBRs) were operated to simulate the activated sludge process. One SBR was spiked with 250 microg/L tetracycline, while the other SBR was evaluated at tetracycline concentrations found in the influent of the wastewater treatment plant (WWTP) where the activated sludge was obtained. The concentrations of tetracyclines in the influent of the WWTP ranged from 0.1 to 0.6 microg/L. Three different operating conditions were applied during the study (phase 1-HRT: 24 h and SRT: 10 days; phase 2-HRT: 7.4 h and SRT: 10 days; and phase 3-HRT: 7.4 h and SRT: 3 days). The removal efficiency of tetracycline in phase 3 (78.4 +/- 7.1%) was significantly lower than that observed in phase 1 (86.4 +/- 8.7%) and phase 2 (85.1 +/- 5.4%) at the 95% confidence level. The reduction of SRT in phase 3 while maintaining a constant HRT decreased tetracycline removal efficiency. Sorption kinetics reached equilibrium within 24 h. Batch equilibrium experiments yielded an adsorption coefficient (Kads) of 8400 +/- 500 mL/g and a desorption coefficient (Kdes) of 22 600 +/- 2200 mL/g. No evidence of biodegradation for tetracycline was observed during the biodegradability test, and sorption was found to be the principal removal mechanism of tetracycline in activated sludge.