Study On The Effect Of Typical Antibiotics On The Process Of Anaerobic Fermentation Of Corn Stalks

With the improvement of human living standards as well as the continuous development of agriculture and animal husbandry,large amount of waste is generated.Research has found that these wastes can be used as high-quality raw materials for the production of clean energy methane.In the process of crop farming and animal husbandry,antibiotics are widely used and became one of the main pollutants in the environment.In order to protect the environment,research on whether agricultural wastes can degrade antibiotics during anaerobic fermentation is urgently needed.This dissertation used antibiotics as examples,abamectin（AVM）and sulfadimethoxine sodium（SDM）were selected as the research objects,their effects on the anaerobic fermentation process of corn stover,including the main indicators of anaerobic fermentation:enzyme,p H,gas production,NH₄⁺-N Changes in and VS,etc,were studied.Additionally,the changes in the methane production potential of corn stalks before and after fermentation were analyzed to evaluate the effects of these two antibiotics on anaerobic fermentation process both in theory and in practice.High-throughput sequencing technology（16s r RNA）was used to analyze the microbial community structure and function changes in the fermentation system under the influence of two antibiotics.（1）Through nonlinear fitting,it was found that the degradation process of the two antibiotics in the anaerobic fermentation process fit the first-order degradation kinetics,the equation was Ct=A2exp（-k_t）-A1,and the correlation coefficient R² was greater than0.9017.Abamectin was completely degraded within 10 days,which was faster than its natural degradation process in the environment.Sulfadimethoxine sodium was completely degraded within 7 days.（2）When the abamectin concentration was below 90mg/L,it showed certain promotion effect on the anaerobic fermentation process,when the concentration was too high,it showed inhibitory effect.At 90 mg/L,the highest cumulative methane production could reach 3325.4 m L.After adding sulfadimethoxine sodium,at concentration below 120mg/L,anaerobic fermentation process was promoted,and when it exceeded 120mg/L,the promotion effect weakened.（3）The theoretical methane production potential（TMP）of the corn stover calculated by the methane prediction model was 302.92 m L CH₄/g VS,and the actual methane production potential（BMP）can be obtained by calculating the actual cumulative methane production.Among the results,the BMP/TMP of the abamectin group reached 77%-95%,and the BMP/TMP of the sulfadimethoxine sodium group reached 84%-96%,indicating that effects of abamectin on the anaerobic fermentation was weaker than that of the sulfadimethoxine sodium group.（4）The modified Gompertz kinetic model revealed that high concentrations of abamectin would increase the lag time of anaerobic fermentation,while sulfadimethoxine sodium would shorten the lag time of fermentation.On the whole,the BMP_∞and Rm obtained by the fitting were consistent with the results of the actual methane production process,indicating that the fitting process is highly reliable.（5）The addition of abamectin and sulfadimethoxine sodium reduced the abundance of the microbial community at phylum level,and the dominant flora transformed from the Bacteroides phylum to Firmicutes and Proteobacteria.The change of Chao1 index showed that there was a certain positive correlation between gas production and Chao1 index.