Effect Of Tetracycline On Nitrogen Removal Performance And Microbial Community Structure In SBR System

Nitrification is an important step in the process of biological nitrogen removal,which includes a variety of microorganisms,which are vulnerable to toxic and harmful substances,such as antibiotics.In recent years,antibiotics are frequently detected in the influent of wastewater treatment plants due to the extensive use of antibiotics,and currently,antibiotic wastewater is mainly treated by biological methods.Therefore,it is of great significance to explore the effect of antibiotics on biological denitrification and the principle of action.In this experiment,tetracycline,which is the most widely used,was added to the SBR biological nitrogen removal system to investigate the short-term and long-term effects of different concentrations of tetracycline on the biological nitrogen removal performance.In the nitrification system.Through the analysis of nitrogen removal efficiency,the change of pollutants in the typical cycle,the change of nitrification type,activated sludge performance,microbial community structure,and diversity,EPS composition,and content.Discuss the influence mechanism of tetracycline on biological denitrification performance.The main results are as follows.(1)Based on the batch studies,it was found that the activities of AOB and NOB decreased with the increase of tetracycline concentration,and the tetracycline concentration was positively correlated with the inhibition rate.(2)Long-term experimental studies have shown that when the concentration of tetracycline is 0mg/L,the activity of AOB and NOB increased with the increase of the operating cycle,and the whole nitrification was full;when the concentration of tetracycline was 5mg/L and 20mg/L,the activities of AOB gradually recovered with the increase of exposure cycle,but NOB gradually inactivates,and the short nitrification process was occured in the later stage.The activities of AOB and NOB decreased with the increase of the exposure cycle when the concentration of tetracycline was 35mg/L,resulting in the collapse of the nitrification system.Tetracycline can inhibit the activity of nitrifying sludge and increase with the increase of tetracycline concentration.At different concentrations of tetracycline,the content of PN was always more than that of PS.(3)The results of the analysis of the bacteria community in 5 groups(15)mud samples showed that the high concentration of tetracycline had a significant influence on the microbial community structure.As the concentration of tetracycline increases,the degree of inhibition of Ferribacterium,Nitrospira and Ferruginibacter is getting stronger,but the inhibitory effect on Zoogloea and Pseudoxanthomonas is getting weaker and weaker.Besides,the activity of Nitrosomonas is completely inhibited at the concentration of 35mg/L.Based on species difference analysis,f＿＿Saprospiraceae,g＿＿Ferruginibacter,g＿＿Thauera,f＿＿Burkholderiaceae and g＿＿Pseudoxanthomonas are significantly dominant species at the original and tetracycline concentrations of 0mg/L,5mg/L,20mg/L,and 35mg/L,respectively.(4)Based on short-term tests,AOB was more resistant to tetracycline than NOB.Under the condition of long-term administration of tetracycline,the greater the tetracycline concentration,the stronger the domesticated AOB to tetracycline.This experiment explored the effect of tetracycline on the biological nitrogen removal of nitrification system,and analyzed the changes of microbial community structure,and clarified the impact of tetracycline on the sewage treatment process,which has important reference significance for the comprehensive assessment of the environmental risk of tetracycline.