The Study On The Effect Of Ferrous Ion Enhanced Electrode-SBBR Process On Simulyaneous Degradation Of Ammonia Nitrogen And Cephalosporin In Water

Antibiotics are widely used in various fields of human life and production.The large amount of unused antibiotics remaining in the water environment has caused serious damage to the natural environment and ecosystem.The traditional biological treatment process has limited ability to degrade antibiotics,and the bio-electrochemical process has a positive effect on improving the removal rate of organic matter in the activated sludge system.In addition,iron ions in the activated sludge method with iron source participate in the metabolic process of microorganisms,which can improve the removal of activated sludge Nitrogen effect.In this paper,an external iron source coupled bio-electrochemical process is used to effectively solve the treatment status of low removal rate of refractory organic matter and poor nitrogen removal effect of activated sludge system.This study designed four biological treatment processes of SBBR,Fe-SBBR,BES,and Fe-BES respectively,and explored the influence of the main process parameters of different biological treatment processes on the degradation effect of pollutants in the biological system and the changes of microbial community structure.The conclusions are as follows.1.The ammonia nitrogen and COD degradation effects of the four processes are good after the filling of the membrane is completed,and a new microbial morphology appears in the reactor in which iron ions are added:"multi-sphere aggregation".The concentration of ceftazidime at the end of antibiotic environmental domestication was increased to 1 mg/L.The ammonia nitrogen removal rates of Fe-SBBR and Fe-BES processes were improved by 9.66%and 9.25%compared to the SBBR and BES processes,respectively.the total nitrogen removal rates were increased by 14.52%and 11.41%,respectively.The removal rates of ceftazidime degradation by BES and Fe-BES processes were 19.59%and 17.64%higher than SBBR and Fe-SBBR,respectively.It is initially proved that the Fe-BES process has the ability to simultaneously degrade ammonia nitrogen and ceftazidime in water.2.The best iron ion dosage of Fe-SBBR and Fe-BES process is 5 mg/L,BES process has the best degradation performance of pollutants when the voltage is 2.5 V,the Fe-BES process achieves the best pollutant degradation effect at 2 V.When the Fe-BES process is in the optimal condition,the ammonia nitrogen removal rate is as high as 92.34%,the total nitrogen removal rate is 88.48%,and the ceftazidime degradation rate is 84.29%,which achieves the simultaneous and efficient degradation of ammonia nitrogen and antibiotics in water.The Fe-BES process is suitable for the treatment of domestic sewage containing single or multiple antibiotics,and the treatment effect is significantly better than other single treatment processes.3.The promoting effect of ferrous ion on the denitrification process is mainly due to two reasons.On the one hand,ferrous ion is involved in both nitrification and denitrification,the added ferrous ion can be used as an electron donor to reduce the nitrate nitrogen in the system to nitrogen,and the generated ferric iron can also be used as an electron acceptor to undergo a redox reaction with the ammonia nitrogen in the reactor to convert the ammonia nitrogen to nitrous nitrogen;On the other hand,iron ions are essential elements for the growth of microorganisms.Iron ions can effectively improve the activities of three key enzymes that control the nitrification process.4.The structure of the microbial community changes significantly after the filling of the membrane completed.The addition of iron ions has no significant effect on the microbial diversity of the biological system.The dominant bacteria in the Fe-SBBR and SBBR processes are Bacteroidetes,Proteobacteria and Actinobacteria.The difference in the degradation effect of the system on pollutants is due to the difference in the number and activity of dominant bacteria.5.The microbial community structure of Fe-BES and BES process is basically the same.When the dosage of ferrous ion is 5 mg/L,the microbial community composition of Fe-BES is evenly distributed.Bacteroidetes,Actinobacteria,Proteobacteria,Patescibacteria and Chlorofelxi in a considerable amount of synergy,to achieve the best pollutant degradation effect.In addition,through the analysis of Beta diversity of microorganisms in different processes,we learned that ferrous ions have a greater influence on the community structure of microorganisms than the external electric field.