| At present,the pollution of antibiotics in the environment has gradually increased,and the scaled livestock and poultry breeding is one of the important sources of environmental antibiotics and resistance gene pollution.The pollution status and removal characteristics have gradually become the focus of attention.In this paper,antibiotics and resistance genes were used as research objects to establish and optimize antibiotic detection methods for livestock and poultry manure.The antibiotic residues and resistance genes in large-scale chicken farms,aerobic composting plants and anaerobic digestion plants in Beijing were investigated.The state of pollution and the degradation of aerobic and thermophilic aerobic digestion under four different conditions of ventilation were studied,including oxytetracycline,sulfamethoxazole,ciprofloxacin and erythromycin.The main conclusions are as follows:Firstly,a solid phase extraction-high performance liquid chromatography tandem mass spectrometry(SPE-HPLC-MS)was established to detect tetracyclines,sulfonamides,quinolones,and macrolide antibiotics in samples.After optimization of the sample pretreatment conditions,the method was validated.The recoveries of the 16 antibiotics were between 61.89%and 97.08%.The detection limit was range from 0.01 to 2.50?g kg-1.The lower limit of quantification was range from 0.05 to 7.86 mg·kg-1,with a linear correlation was range from 0.9914 to 0.9996.The method is convenient,cheap,accurate and sensitive.The method was applied to analyse antibiotic residues in chicken manure,organic manure and biogas residues from typical large-scale chicken farms,aerobic composting plants and anaerobic fermentation plants in Beijing.The results showed that the detection rate of the four antibiotics in all samples was 100%,and the concentration of antibiotics in anaerobic fermentation plants was higher than that in aerobic composting plants.Secondly,the qualitative analysis and quantitative analysis of resistance genes(ARGs)in chicken manure,organic manure and biogas residues were performed.Seventeen representative resistance genes were selected from 78 resistance genes for quantitative analysis by dPCR.The detection rate of antibiotic ARGs was above 90%,and the detection rates of tetracycline resistance genes tetA1,tetMZ and sulfonamide resistance genes sul11 and dfrAl reached 100%.Different fecal sources have a great influence on the presence of tetracycline resistance genes in different mechanisms.Finally,a composting simulation experiment was designed to study the degradation of four antibiotics such as tetracycline,sulfamethoxazole,ciprofloxacin and erythromycin.This article mainly studied the effect of thermophilic aerobic digestion on the removal of four kinds of antibiotics in chicken manure under different ventilation methods,clarified the influence of different ventilation conditions on the antibiotic removal effect,and discussed the temperature,moisture content,pH,EC and GI in the composting process..There were three experimental groups:stewing compost,natural ventilation and forced ventilation.The removal rates of antibiotics of forced ventilation is the highest in the three treatment groups,natural ventilation is lower than forced ventilation,and stationary composting is the lowest of three groups.The removal rate of them was range from 90.0%to 99.9%.Compared with normal composting systems,the addition of antibiotics did not affect the performance of the composting experiment.The degradation of the antibiotics in the compost can be simulated by the first-order kinetic equation,and the correlation coefficient is range from 0.3144 to 0.9950.Forced ventilation has the shortest half-life and stationary composting has the longest half-life among the three treatment,indicating that adequate oxygen and regular turnover can promote the degradation of antibiotics and increase the rate of antibiotic degradation. |
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