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 sul...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 μg/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 （logKd） 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.展开更多
This work aimed to study UV-resistant strains of Pseudomonas aeruginosa, to propose a formulation of the kinetics of secondary treated wastewater disinfection and to underline the influence of suspended solids on the ...This work aimed to study UV-resistant strains of Pseudomonas aeruginosa, to propose a formulation of the kinetics of secondary treated wastewater disinfection and to underline the influence of suspended solids on the inactivation kinetics of these strains. Some investigations were carried out for the validation of some simulation models, from the simplest, the kinetics model of Chick-Watson reduced to first order, to rather complex models such as multi-kinetic and Collins-Selleck models. Results revealed that the involved processes of UV irradiation were too complex to be approached by a simplified formulation, even in the case of specific strains of microorganisms and the use of nearly constant UV radiation intensity. In fact, the application of Chick-Watson model in its original form is not representative of the kinetics of UV disinfection. Modification, taking into account the speed change during the disinfection process, has not significantly improved results. On the other hand, the application of Collins-Selleck model demonstrates that it was necessary to exceed a least dose of critical radiation to start the process of inactivation. To better explain the process of inactivation, we have assumed that the action of disinfectant on the survival of lonely microorganisms is faster than its action on suspended solids protected or agglomerated to each others. We can assume in this case the existence of two inactivation kinetics during the processes （parallel and independent） of the first-order. For this reason, the application of a new kinetic model by introducing a third factor reflecting the influence of suspended solids in water on disinfection kinetics appeared to be determinant for modeling UV inactivation of P. aeruginosa in secondary treated wastewater.展开更多
基金supported by the National Natural Science Foundation of China (No. 50878206, 50921064)the Ministry of Science and Technology of China (No. 2007AA06Z344,2009BAC57B02, 2009AA063901)
文摘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 μg/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 （logKd） 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.
基金supported by the European Union (Avi-cenna Project No. 93AVI054)
文摘This work aimed to study UV-resistant strains of Pseudomonas aeruginosa, to propose a formulation of the kinetics of secondary treated wastewater disinfection and to underline the influence of suspended solids on the inactivation kinetics of these strains. Some investigations were carried out for the validation of some simulation models, from the simplest, the kinetics model of Chick-Watson reduced to first order, to rather complex models such as multi-kinetic and Collins-Selleck models. Results revealed that the involved processes of UV irradiation were too complex to be approached by a simplified formulation, even in the case of specific strains of microorganisms and the use of nearly constant UV radiation intensity. In fact, the application of Chick-Watson model in its original form is not representative of the kinetics of UV disinfection. Modification, taking into account the speed change during the disinfection process, has not significantly improved results. On the other hand, the application of Collins-Selleck model demonstrates that it was necessary to exceed a least dose of critical radiation to start the process of inactivation. To better explain the process of inactivation, we have assumed that the action of disinfectant on the survival of lonely microorganisms is faster than its action on suspended solids protected or agglomerated to each others. We can assume in this case the existence of two inactivation kinetics during the processes （parallel and independent） of the first-order. For this reason, the application of a new kinetic model by introducing a third factor reflecting the influence of suspended solids in water on disinfection kinetics appeared to be determinant for modeling UV inactivation of P. aeruginosa in secondary treated wastewater.
