Denitrification Characteristics Of Heterotrophic Nitrification-aerobic Denitrification Bacteria YH01,YH02 And Microbial Structure During Enhancing Nitrogen Removal

The heterotrophic nitrification-aerobic denitrification bacteria XH03,YH01,YH02and FX03,isolated from aerobic sludge,were systematically investigated as the research subject.They were identified as Pseudomonas,Delftia,Acidovorax and Pseudomonas on the base of phylogenetic analysis of 16S rDNA gene sequence,respectively.Further denitrification characteristics and denitrification mechanism of strains were investigated.The synergistic and competitive of strains were studied,and the effect of YH01+YH02 on nitrogen removal in the reactor was investigated.Microbial structure and diversity in the reactor were analyzed by high throughput sequencing technology.The main results are as follows.?1?The most suitable conditions of XH03,YH01,YH02 and FX03 in heterotrophic nitrification were as follows:the carbon source all were sodium citrate,the temperature were 30?,25?,30?and 30?,the pH were 7.5,7,7 and 7.5,the C/N were 8,6,8 and 8,the speed all were 120r/min.The ammonia removal efficiencies for XH03,YH01,YH02 and FX03 were 87.8%,89.7%,88.3%and 87.8%after 72 hours in this condition,rspectively.The most suitable conditions of XH03,YH01,YH02 and FX03 in aerobic denitrification are as follows:the carbon source all were sodium citrate,the temperature were 30?,25?,25?and 30?,the pH were7.5,8,8 and 7.5,the C/N were 8,6,8 and 8,the speed all were 120r/min.The nitrate removal efficiencies were 89.7%,89.3%,91.7%and 60.9%after 72 hours during the denitrification,rspectively.?2?XH03,YH01,YH02 and FX03 all contain AMO,HAO and NAP.Strains of XH03,YH01 and YH02 contain NIR,but no NOR,and denitrification pathway was NH₄⁺-N?NH₂OH?NO?N₂O.FX03 contains both NIR and NOR,and denitrification pathway was NH₄⁺-N?NH₂OH?NO₂^--N?NO₃^--N.?3?XH02 and XH03,YH01 and YH02 were able to cooperatively promote growth with each other,and denitrification efficiency was improved compared with the single strain.When the initial nitrogen concentration was 100mg/L,the ammonia removal efficiencies were 97.1%and 93.8%after 24h in the process of heterotrophic nitrification,respectively.The nitrate removal efficiencies were 96.7%and 97.8%after 24h during the denitrification,respectively.?4?The removal rate of NO₃^--N,TN and COD were increased by 12.2%,7.2%and 9.5%in the aerobic SBR reactor enhanced by strain respectively;The relative abundance and biological diversity in the enhanced reactor showed a trend of increasing and then decreasing.PCA and cluster analysis are generally divided into 4stages,which correspond to the range from 0³d,6d,9¹5d and 18²1d.The change trend of YH01 was first increased and then decreased,YH02 was first increased and then stabilized.?5?The removal rate of COD and NO₃^--N was more than 90%in two stage aerobic SBR nitrogen removal process enhanced by YH01+YH02 when the C/N was8;The relative abundance of YH01 and YH02 were 4.2%and 2.6%in reactor B,respectively.