Nitrogen removal efficiency and mechanism of Feammox/NDFO coupling process in electrochemical system
In order to improve the defects of the slow start-up and poor nitrogen removal efficiency of the Feammox/NDFO coupling process,a strategy to strengthen the start-up of Feammox/NDFO coupling process based on the principle of electrochemistry was proposed in this paper.The anaerobic sequencing batch reactor based on bio electrochemical system(BES)(named B group by authors)was built in the laboratory,and take an general anaerobic sequencing batch reactor(A group)without bio-electrochemical systems as the control group.Reactors A and B were operated for 100 days.The nitrogen removal efficiency,nitrogen removal pathway verification and microbial structure during the start-up process were analyzed,and the mechanism of enhanced denitrification in reactor B system was discussed.The results showed that the NH4+-N removal rate of reactor B was significantly improved,with the removal rate reaching approximate 100%and the TN removal rate reaching 65.83%on the 76th day.However,the NH4+-N and TN removal rates reached 50.22%and 43.01%on the 100 th day in group A.The results of nitrogen removal pathway verification experiment showed that Feammox,NDFO and Anammox reactions were all occurred in both groups A and B,and denitrification rate in group B was higher than that of group A.Compared to group A,the relative abundance of Desulfobacterota which belongs to Feammox/NDFO functional bacteria in in group B was higher than group A with 2.34%.And Thiobacillus and Denitratisoma were higher 1.1.3 and 0.87%than those of group A.BES could accelerate the enrichment of Feammox functional bacteria and denitrifying bacteria,and these bacteria could carry out extracellular electron transfer through BES electrode to enhance nitrogen removal efficiency.
Fe(III)reduction coupled to anaerobic ammonium oxidationnitrate-dependent Fe2+oxidationbio-electrochemical systemsnitrogen removal
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