Removal Of Antibiotics During Aerobic Fermentation Of Livestock Manure

As a kind of antibacterial drug,antibiotics are often used in livestock and poultry breeding to prevent animal diseases and improve feed conversion rate.However,only a small part of antibiotics can be absorbed,and 30%to 90%of antibiotics are excreted via the manure in the form of original drugs and metabolites.Faeces containing antibiotics are directly applied to farmland,resulting in the destruction of the soil environment.Antibiotics are absorbed by plants and passed into the human body through the food chain,eventually becoming a major hidden danger to human health.In this article,aiming at the residual problems of sulfonamides(SAs),quinolones(FQs)and tetracyclines(TCs)in livestock and poultry manure,two different aerobic fermentation processes were applied to explore the degradation rate and influencing factors of antibiotics in the process of aerobic fermentation of livestock and poultry manure.The main conclusions of this paper are as follows:(1)A set of liquid chromatography tandem mass spectrometry(LC-MS/MS)methods for the combined detection of 20 antibiotics in three major categories of livestock and poultry feces have been established,and the method has been optimizated and improved from both pre-processing methods and working conditions of chromatograph and mass spectrometer.The limit of detection(LOD)and limit of quantification(LOQ)of this method were 0.03?19.23 ?g·L-1 and 0.15?54.82 ?g·L-1,respectively.(2)The high-temperature enzymatic hydrolysis and rapid decomposition process have been used to explore the removal of antibiotics in the process of aerobic fermentation of cow manure.The effect of reaction time,reaction temperature,and initial antibiotic concentration(IAC)on the removal rate of antibiotics was explored by response surface method design.The antibiotic removal was obtained through model fitting,and the optimal reaction conditions were as follow:The cow manure in the reactor equipped with external heating and stirring devices,under the action of the enzyme preparation,undergoes a fermentation reaction of up to 2.66 h and 76?,and the antibiotic removal rate(94.85%)can be reached.This parameter was subsequently used for validation experiments,and the actual antibiotic removal rate was 92.47%,which was close to the predicted value and verified the reliability.(3)A 110-day aerobic fermentation experiment was carried out using traditional composting fermentation combined with turning and throwing technology.Four common livestock manures including chicken manure,pig manure,cow manure and sheep manure mixed straw were combined with different microbial inoculants(A,B,C,D),and a blank control group was set up(without inoculation),to investigate the changes in the chemical properties of the above manure and the removal effect of antibiotics during the composting experiment.The degradation efficiency of antibiotics during aerobic fermentation and the changes in physical and chemical properties were exploried during composting.The experiment found that when the initial antibiotic concentration in cow manure is low(5ppm),the average removal rate of antibiotics is 90.41%,and the maximum removal rate of tetracycline can reach 99.53%.When the initial antibiotic concentration was high(50 ppm),the antibiotic removal rate was significantly reduced to 80.12%.Among the four microbial inoculants,inoculum B showed the best effect on promoting the maturity of the pile and accelerating the degradation of antibiotics.Inoculum A has a significant positive effect on rapid temperature increasing the of the manure and shortening the time for the manure to reach the high temperature period.