The Research On Removal Of Several Antibiotics In Chicken Manure By Composting

Antibiotics are widely used in livestock and poultry farming,and cannot be completely digested by livestock and poultry,existing as parent compounds or metabolites in the soil environment by livestock manure.Antibiotics produce the ecotoxicological effects in environment,even induce the resistance genes,trigger a series of ecological and environmental problems.Common antibiotics,like tetracyclines,fluoroquinolones and sulfonamides were taken as the research object of this paper,(Tetracycline TCT,Oxytetracycline OTC,Norfloxacin NOR,Enrofloxacin ENR,Sulfamethazine SMZ;Sulfamethoxazole SMX).This study established a highly efficient and economic method for the simultaneous determination of six common antibiotics,in chicken manure,using solid-phase extraction and high performance liquid chromatographic(SPE-HPLC).This study researched the optimal composting conditions and removal effect of antibiotics through orthogonal experiments to control composting conditions,improved the effects of antibiotics removal rate by composting treatment technology,and discussed the variation rules of antibiotics removal and the physical and chemical properties in the aerobic composting.The main results were as follows:1 A highly efficient and economic method for the simultaneous determination of antibiotics(two tetracyclines,two quinolones and two sulfonamides),in chicken manure,were developed using solid-phase extraction and high performance liquid chromatographic(SPE-HPLC).The results showed that in the range of 0.5 to 100 mg·L-1,the correlation coefficients(r2)of all antibiotics was between 0.9999 and 1.The recoveries of antibiotics were between 70.0%and 116.3%,and the relative standard deviations(RSD)were between 1.2%and 16.6%.The limit of detection(LOD)was 1.3-6.7 ?g·kg-1,and the limit of quantity(LOQ)was 3.5-9.2 ?g·kg-1.This method was used to detect antibiotics in chicken manure from a hennery in Liaoning Fushun Province,the content of norfloxacin and enrofloxacin(the quinolones)were ND(not detect)-9.23 mg·kg-1 and 1.57-7.69 mg·kg-1;and the content of sulfamethazine(the sulfonamides)was 2.02-13.05 mg·kg-1,sulfamethoxazole?oxytetracycline and tetracycline was not detected.2 The optimal composting process parameters were determined by 3 factors(turnover frequencies,moisture and chicken manure sawdust mass ratio)and 3 levels of orthogonal experiments.According to the removal consequences of antibiotics,this study proceeded the range analysis and variance analysis on the factors that affecting the removal results of antibiotics in the experiment,and finally determined the optimal composting process of orthogonal experiments.The optimal parameter combination was A2B3C3,when the turnover frequency was 3 times/day—the water content was 60%—the mass ratio of chicken manure sawdust was 2:1,the removal results of the six antibiotics was the highest.The factors effects on composting experiments were arranged in descending order:frequency of turnover>moisture content>mass ratio of chicken manure sawdust.3 During the composting process,the total carbon(TC)and organic matter(OM)content of the heap decreased during the composting process,reduced 11.9%and 28.9%,respectively.The decomposition abilities of microorganisms were higher in the high temperature period during composting,and removal rates were faster,after the high temperature period,the abilities of microorganisms were weak,the removal rates slowed down.The total nitrogen(TN)content decreased in the first place and then increased,increased 0.27 overall.The carbon to nitrogen ratio(C/N ratio)showed a slight increase and then decreased,and stabilized at 25.9 finally.4 The removal rates of 6 antibiotics reached 92.73%-98.96%during 42 days composting.The removal result of norfloxacin(NOR)was the best,reaching 98.96%,and the removal result of oxytetracycline(OTC)was the worst,only 92.73%.The concentration(C)and time(t)curves of the six antibiotics had a good exponential relationship.The changed of concentration of all antibiotics accord with the first-order kinetic model,and the correlation coefficient(R2)reached 0.96-0.99.The half-lives of oxytetracycline,tetracycline,norfloxacin,sulfamethazine and enrofloxacin were 1.7,2.9,2.8,2.3,1.3 and 2.9 days,respectively.The rates of degradation were arranged in descending order:sulfamethoxazole>norfloxacin>sulfamethazine>tetracycline>enrofloxacin>oxytetracycline.