Study On Anaerobic Degradation And Ecotoxicity Of Macrolide Antibiotics

As clinical medical technology becomes more and more mature,more and more antibiotics are used in the treatment of many diseases.In treatment methods of antibiotic wastewater,based on literature,biodegradation and adsorption treatment may be an important approach to the removal of antibiotics in wastewater.This paper studies the degradability and anaerobic toxicity of antibiotics in simulated wastewater under anaerobic conditions.According to literature data,studies on the treatment methods of tetracyclines and sulfa antibiotics are relatively common,but there are few degrading methods for macrolides antibiotics,in particular the method of anaerobic biodegradation used in this paper.In the field of macrolide antibiotics treatment methods,it is very rare.Therefore,we have made a series of anaerobic degradation experiment under different concentration aiming at macrolide antibiotics in order to investigate the macrolides in this method.Therefore,if this kind of method can make antibiotics be effectively degraded will be discussed,at the same time providing more reference for future antibiotic treatment.In addition,the assessment of the ecotoxicity of antibiotics is generally based on the study of the ecotoxicity of microorganisms,plants,animals,and soil organisms.The anaerobic toxicity test is used in this paper.Glucose is used as a co-substrate and antibiotics are used as test sample.The method is used to determine the corresponding indicators and the methanogenic toxicity of antibiotics during anaerobic degradation under anaerobic conditions.This method has a short experimental period and is easy to operate and can intuitively determine the toxicity through the index of relative activity(RA).The experimental procedure is designed according to the ECETOC international standard test method.This test method not only saves time and effort,but also requires only the serum bottle culture sludge,and then add the test substance directly for anaerobic degradation,the operation is simple,and finally can be intuitively drawn degradation rate of every antibiotic.The macrolide antibiotics involved in this article are limited to macrocyclic lactones of 14 to 16 yuan carbocycle,and the selected antibiotics are those containing 99% or more of the original antibiotics.The four macrolide antibiotics are:(1)erythromycin: a representative of the first generation of macrolide antibiotics and belongs to the 14 yuan carbocycle;(2)azithromycin: as the second-generationmacrolides antibiotics,belonging to the 15 yuan carbocycle,are derivatives of erythromycin:(3)clarithromycin: a second-generation macrolide antibiotic that belongs to the 14 yuan carbocycle and is a derivative of erythromycin;(4)spiramycin: spiramycin alone is one kind,belonging to 16 yuan carbocycle.Therefore,observing the anaerobic degradation and ecotoxicity of four different kinds of macrolide antibiotics has certain reference value for understanding and knowing the degradation performance and toxicity of such antibiotics.Thus,in this experiment,four kinds of macrolide antibiotics were bottled and cultured respectively,inorganic nutrient salts and anaerobic activated sludge were added to prepare the culture fluid,and the amount of biogas generated was measured each day to calculate the amount of methane and carbon dioxide as well as the content of VFAs when the experiment is completed,and pretreat the liquor after the reaction,then the inorganic carbon content in the solution is determined,and the degradation rate of the test substance is finally determined.Toxicity experiments include the addition of sludge,inorganic nutrients,and glucose to the solution.Each day,the amount of gas produced must also be measured.Comparing the amount of methane produced by the test substance and the blank control experiment,and examine the strength of inhibition of the methanogen.in order to determine the toxicity of antibiotics.The experimental results show that the order of degradation rates of the four antibiotics is:azithromycin > clarithromycin > erythromycin > spiramycin.The order of toxicity of the four macrolide antibiotics in the toxicity experiment was: spiramycin > erythromycin > clarithromycin > azithromycin.It also proves that,in the process of anaerobic degradation,the inhibition of methanogens by the macrolide antibiotic itself directly determines the degree of difficulty in the degradation process.Except spiramycin,as the carbon atoms on the mother nucleus increase,the degradation rate of others also increases,presumably due to the presence of C=C bonds and C=O bonds in the spiramycin nucleus,resulting in 16-membered macrolides ring is hardly destroyed,or the structure inhibits the methanogenic process,making it difficult to mineralize the organic matter.