Weiwei Ben

Simultaneous determination of sulfonamides, tetracyclines and tiamulin in swine wastewater by solid-phase extraction and liquid chromatography-mass spectrometry.

Little is known about the contamination level of antibiotics in swine wastewater in China. The highly complex matrix of swine wastewater, which generally has a chemical oxygen demand (COD) concentration as high as 15,000 mg/L, makes it difficult to detect antibiotics at trace levels. In this work, a highly selective and sensitive analytical method was developed for simultaneous determination of three classes of commonly used veterinary antibiotics including five sulfonamides, three tetracyclines and one macrolide in swine wastewater using solid-phase extraction (SPE) and liquid chromatography-mass spectrometry (LC-MS). The method detection limits (MDL) in the swine wastewater were determined to be between 5 and 91 ng/L, depending on specific antibiotics. Except sulfamethizole, all the other eight antibiotics were detected in the swine wastewaters collected from three concentrated swine feeding plants located in the Beijing (China) area, showing a concentration range of 0.62-32.67 microg/L. These results reveal the representative concentration levels of selected antibiotics in the swine wastewaters of Beijing area.

Residual veterinary antibiotics in swine manure from concentrated animal feeding operations in Shandong Province, China

The scientific interest in the occurrence and fate of antibiotics in animal husbandry has increased during the past decades because of the emergence and development of antimicrobial resistance in pathogenic bacteria. This study developed a method for simultaneous detection of five sulfonamides, three tetracyclines and one macrolide in swine manure with stable recoveries (73.0-110.6%) and high sensitivity (limit of quantification <90 μg kg(-1)). Thereafter, a total of 126 swine manure samples, collected from 21 concentrated animal feeding operations (CAFOs) in Shandong Province of China during summer and winter, were analyzed. The potential influences of different sampling seasons, swine types and food sources on residual antibiotic concentrations were examined in detail. The maximum concentration of residual antibiotic could reach up to 764.4 mg kg(-1) (chlortetracycline), and the detection frequencies were 84.9-96.8% for tetracyclines, 0.8-51.6% for sulfonamides and 4.8% for macrolide. These data reveal that antibiotics were extensively used in CAFOs in this district and the manure may act as a non-specific source of antibiotic residue in farmlands and aquatic environments.

Removal of veterinary antibiotics from sequencing batch reactor (SBR) pretreated swine wastewater by Fenton's reagent

The large-scale application of veterinary antibiotics in livestock industry makes swine wastewater an important source of antibiotics pollution. This work investigated the degradation of six selected antibiotics, including five sulfonamides and one macrolide, by Fentons reagent in swine wastewater pretreated with sequencing batch reactor (SBR). The dosing mode and practical dosage of Fentons reagent were optimized to achieve an effective removal of antibiotics while save the treatment cost. The effects of initial pH, chemical oxygen demand (COD) and suspended solids (SS) of the SBR effluent on antibiotics degradation were examined. The results indicate that the optimal conditions for Fentons reagent with respect to practical application were as follows: batch dosing mode, 1.5:1 molar ratio of [H(2)O(2)]/[Fe(2+)], initial pH 5.0. Under the optimal conditions, Fentons reagent could effectively degrade all the selected antibiotics and was resistant to the variations in the background COD (0-419 mg/L) and SS (0-250 mg/L) of the SBR effluent. Besides, Fentons reagent helped to not only remove total organic carbon (TOC), heavy metals (As, Cu and Pb) and total phosphorus (TP), but also inactivate bacteria and reduce wastewater toxicity. This work demonstrates that the integrated process combining SBR with Fentons reagent could provide comprehensive treatment to swine wastewater.

MCM-48 modified magnetic mesoporous nanocomposite as an attractive adsorbent for the removal of sulfamethazine from water

A novel magnetic mesoporous nanocomposite FeM48 was synthesized and applied to remove sulfamethazine (SMN) from water. The adsorption kinetics could be expressed by the pseudo-second-order model, where external and interfacial diffusions tended to be the rate-limiting step. The adsorption isotherms at varied temperatures were fitted well with Freundlich model, and thermodynamic analysis revealed that SMN adsorption on FeM48 was a spontaneous exothermic process. Solution pH exhibited a remarkable impact on the adsorption process and the maximum adsorbed concentration was obtained at pH 6.3. The effect of co-existing anions and humic acid demonstrated that SMN could be adsorbed selectively by FeM48. Hydrogen bonding between the nitrogen of the aniline, sulfinol or pyrimidine group of SMN and the surface hydroxyl group of FeM48 was the major driving force for adsorption. In addition, the π-π electron-donor-acceptor interaction between SMN (π-electron-acceptor) and MCM-48 (π-electron-donor) also promoted the adsorption process.

Degradation of endocrine-disrupting chemicals during activated sludge reduction by ozone

Ozonation has been considered to be an effective means for the reduction of excess sludge in recent years. However, it remains largely unknown whether hydrophobic organic micro-pollutants, which are originally adsorbed on activated sludge, will be released into wastewater upon ozonation because of sludge solubilization. This study investigated the degradation efficiencies of several typical endocrine-disrupting chemicals (EDCs) during sludge ozonation, including estrone (E1), estriol (E3), 17α-ethynylestradiol (EE2), bisphenol A (BPA), and 4-nonylphenol (NP). Results indicate that the EDCs present in activated sludge could be effectively removed by O3 even though the apparent rate constants in sludge were 3-4 orders of magnitude lower than those in water. However, the applied O3 dose should be prudently controlled because a low dose (e.g., 29mgO3g(-1)SS) may lead to an increase of BPA and NP concentrations in the liquid phase of activated sludge. Furthermore, H2O2 addition or pH adjustment could improve the removal of most studied EDCs, but exert a negative effect on the more hydrophobic and refractory compound, NP.

Rapid detection of multiple class pharmaceuticals in both municipal wastewater and sludge with ultra high performance liquid chromatography tandem mass spectrometry

This work described the development, optimization and validation of an analytical method for rapid detection of multiple-class pharmaceuticals in both municipal wastewater and sludge samples based on ultrasonic solvent extraction, solid-phase extraction, and ultra high performance liquid chromatography-tandem mass spectrometry quantification. The results indicated that the developed method could effectively extract all the target pharmaceuticals (25) in a single process and analyze them within 24min. The recoveries of the target pharmaceuticals were in the range of 69%-131% for wastewater and 54%-130% for sludge at different spiked concentration levels. The method quantification limits in wastewater and sludge ranged from 0.02 to 0.73ng/L and from 0.02 to 1.00μg/kg, respectively. Subsequently, this method was validated and applied for residual pharmaceutical analysis in a wastewater treatment plant located in Beijing, China. All the target pharmaceuticals were detected in the influent samples with concentrations varying from 0.09ng/L (tiamulin) to 15.24μg/L (caffeine); meanwhile, up to 23 pharmaceuticals were detected in sludge samples with concentrations varying from 60ng/kg (sulfamethizole) to 8.55mg/kg (ofloxacin). The developed method demonstrated its selectivity, sensitivity, and reliability for detecting multiple-class pharmaceuticals in complex matrices such as municipal wastewater and sludge.

Occurrence and partition of antibiotics in the liquid and solid phases of swine wastewater from concentrated animal feeding operations in Shandong Province, China

Swine wastewater represents an important pollution source of antibiotics in the environment; however, regional data about residual antibiotics in swine wastewater are very limited at present. This study investigated the concentrations of three classes of commonly used veterinary antibiotics, including five sulfonamides (SAs), three tetracyclines (TCs) and one macrolide (tiamulin, TIA), in swine wastewater collected from 21 concentrated animal feeding operation (CAFO) sites in Shandong Province, China. Both the liquid and solid (i.e., suspended solids) phases of swine wastewater were analyzed to determine the total concentration of each studied antibiotic. Results indicate that sulfamethazine had the highest median concentration (14.56 μg L(-1)), followed by oxytetracycline (OTC, 8.05 μg L(-1)) and chlortetracycline (CTC, 6.01 μg L(-1)). The maximum detected concentration reached up to 2.02 mg L(-1) (OTC) and the highest detection frequency was 95.1% (CTC). The median concentrations and detection frequencies of antibiotics in winter samples were generally higher than those in summer samples (except CTC). The log Kd values were in the range of 1.31-1.96 for SAs, 2.05-2.33 for TCs, and 1.54-1.58 for TIA in swine wastewater. More TCs (14-28%) preferred to partition in the solid phase than SAs (2-10%) and TIA (5-10%), indicating that the suspended solids of swine wastewater may not be ignored.

Impact of reflection on the fluence rate distribution in a UV reactor with various inner walls as measured using a micro-fluorescent silica detector

An assessment of the impact of ultraviolet (UV) reflection from inner walls is important for the accuracy of model predictions of fluence rate (FR) distribution and for the improvement of reactor efficiency. In this study, the FR distribution in an annular UV reactor with inner walls of various reflectances was measured in-situ by using a 360° response micro-fluorescent silica detector. The tests were performed in water with various transmittances ranging from 65% to 99% and with inner reactor walls composed of quartz/aluminum foil, quartz/stainless steel, or quartz/black cloth, whose reflection coefficients were determined to be 80.5%, 26.1% and 11.1%, respectively. The results demonstrate that an inner wall with a high reflection coefficient can lead to a marked increase in the weighted average FRs, thus greatly improving the reactor efficiency. Furthermore, the presently used FR distribution models could have an error of up to 35% for commonly used stainless steel walls as a result of the influence of inner-wall reflection. Finally, it was found that the uniformity of the FR distribution is strongly dependent on the diffuse reflection property of the inner wall, which could lead to a better fluence delivery distribution in the UV reactor. This work has potential application to increase the accuracy of model predictions as well as optimize the design of high-efficiency UV reactors.

Simultaneous determination of three classes of antibiotics in the suspended solids of swine wastewater by ultrasonic extraction, solid-phase extraction and liquid chromatography-mass spectrometry

This work describes a systematic approach to the development of a method for simultaneous determination of three classes of veterinary antibiotics in the suspended solids (SS) of swine wastewater, including five sulfonamides, three tetracyclines and one macrolide (tiamulin). The entire procedures for sample pretreatment, ultrasonic extraction (USE), solid-phase extraction (SPE), and liquid chromatography-mass spectrometry (LC-MS) quantification were examined and optimized. The recovery efficiencies were found to be 76%-104% for sulfonamides, 81%-112% for tetracyclines, and 51%-64% for tiamulin at three spiking levels. The intra-day and inter-day precisions, as expressed by the relative standard deviation (RSD), were below 17%. The method detection limits (MDLs) were between 0.14 and 7.14 microg/kg, depending on a specific antibiotic studied. The developed method was applied to field samples collected from three concentrated swine feeding plants located in Beijing, Shanghai and Shandong province of China. All the investigated antibiotics were detected in both SS and liquid phase of swine wastewater, with partition coefficients (logK(d)) ranging from 0.49 to 2.30. This study demonstrates that the SS can not be ignored when determining the concentrations of antibiotics in swine wastewater.

Dissemination of veterinary antibiotics and corresponding resistance genes from a concentrated swine feedlot along the waste treatment paths.

Swine feedlots are an important pollution source of antibiotics and antibiotic resistance genes (ARGs) to the environment. This study investigated the dissemination of two classes of commonly-used veterinary antibiotics, namely, tetracyclines (TCs) and sulfonamides (SAs), and their corresponding ARGs along the waste treatment paths from a concentrated swine feedlot located in Beijing, China. The highest total TC and total SA concentrations detected were 166.7mgkg(-1) and 64.5μgkg(-1) in swine manure as well as 388.7 and 7.56μgL(-1) in swine wastewater, respectively. Fourteen tetracycline resistance genes (TRGs) encoding ribosomal protection proteins (RPP), efflux proteins (EFP) and enzymatic inactivation proteins, three sulfonamide resistance genes (SRGs), and two integrase genes were detected along the waste treatment paths with detection frequencies of 33.3-75.0%. The relative abundances of target ARGs ranged from 2.74×10(-6) to 1.19. The antibiotics and ARGs generally declined along both waste treatment paths, but their degree of reduction was more significant along the manure treatment path. The RPP TRGs dominated in the upstream samples and then decreased continuously along both waste treatment paths, whilst the EFP TRGs and SRGs maintained relatively stable. Strong correlations between antibiotic concentrations and ARGs were observed among both manure and wastewater samples. In addition, seasonal temperature, and integrase genes, moisture content and nutrient level of tested samples could all impact the relative abundances of ARGs along the swine waste treatment paths. This study helps understand the evolution and spread of ARGs from swine feedlots to the environment as well as assess the environmental risk arising from swine waste treatment.