Screening of a simultaneous nitrification and denitrification strains and its bio-electrochemical nitrogen removal performance
[Objectives]The paper aimed to obtain the heterotrophic nitrification-aerobic denitrification(HN-AD)functional strain with efficient nitrogen removal performance for nitrogen removal efficiency in a coupled bio-electrochemical-synchronous nitrification denitrification(BES-SND)system.[Methods]The HN-AD strain was screened from activated sludge after three steps of isolation,initial screening and re-screening,and its nitrogen removal performance was analyzed by shake flask test after morphological observation.Then the effects of carbon source,C/N,dissolved oxygen and other external factors on the strain's synchronous nitrification denitrification performance were investigated.The strain was inoculated onto the biocathode of microbial fuel cells(MFC)to analyze the denitrification performance of the BES-SND system under low C/N conditions.[Results]A HN-AD strain with simultaneous nitrification denitrification performance was screened from activated sludge,which was named as Alcaligenes aquatilis N3.The optimal carbon source for the SND reaction of this strain was determined to be sodium acetate,C/N=20,and dissolved oxygen 3.70 mg·L-1.In the BES-SND denitrification system,it was found that the total nitrogen(TN)removal rates of A.aquatilis N3 were 20.51％,26.67％,37.76％and 48.50％at C/N of 2,4,6,and 8,respectively.Under the experimental condition of C/N=2,the TN removal rate of the BES-SND system was still 1.79 mg·L-1·d-1 on the fifth day.[Conclusion]Under the low carbon environment,strain A.aquatilis N3 could still realize nitrogen removal in the BES-SND coupled denitrification system,which reduced the dependence of the denitrification process on the carbon source dependence,which has some potential for practical environmental applications.
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