Denitrifying Phosphorus Removal Characteristics And Microbial Community Structure Of Denitrifying Phosphorus Removal Sludge

Denitrifying phosphorus removal process exhibited efficient treatment for domesticsewage with low carbon-nitrogen ratio. A novel A2N/BAF process was developedrecently, with the high efficiency in removing the COD, TN and TP. However, there waslittle research on the denitrifying phosphorus removal bacteria (DPB) up to now and theclassification of DPB was still in disputation. Most reported DPBs were based on theculture-depend techniques which were complex and had little information. In thisresearch, the high-throughput sequencing technology were applied to study themicrobial community of the DPB, and physiological characteristics of DPB wasresearched simultaneously.In this study, the A/A-SBR and A/O-SBR were used for acclimation of the DPBand PAO with the simulated sewage as influent. The acclimation time were47d and33d,respectively. The average amount of phosphorus removal rates were84.5%and85.5%during the8months operation.The average amount of phosphorus removal rates were4.52and4.72mg/(L·h) forinstantaneous and continuous dosing of NO3--N. The amount of phosphorus releaseddecreased almost from18mg/L to1mg/L within5d when the COD was increased from120mg/L to170mg/L. On the other hand, suitable amount of COD (30~60mg/L) dosagein the anoxic stage was favored for the removal of phosphorus and nitrogen. In addition,no denitrification occurred in absence of phosphorus, indicating PHB in the bacteriawas not a suitable carbon source for denitrfication.The phosphorus concentration of the sludge was about5%and6%for A/A reactorand A/O reactor, higher than the ordinary sludge. The picine PHB particles in thebacteria could be observed after staining. Moreover, the sludge SEM morphologyshowed that brevibacterium dominated in the A/A system and the microbial communityof the A/O was more complex than A/A syetem.The diversity of the microbial community showed that the seeding sludge had thehighest diversity. After acclimatization, the diversity of the A/O-SBR was reduced andthe A/A-SBR had the lowest diversity. During the stable operation, the-proteobacteriaand-proteobacteria were dominant in the A/A-SBR and the-、-and-proteobacteriawere the dominant group of A/O-SBR on tne level of Phylum. On the level of genus, thedominant bacteria in A/A-SBR were Methylibium、Thauera and the dominant bacteria inA/O-SBR were Rhodoferax、Propionivibrio、Flavobacterium. The microbial communityof A/A reactor and A/O reactor had the great differences, these results preferred theopinion that PAO and DPB were two different bacteria. Through the comparison of the sequences of the two SBR with the known PAOsequences, the ratios of similar sequences were2.36%,0.16%and4.26%for theseeding sludge, A/A-SBR and A/O-SBR. Phylogenetic tree was built with the sequencesof the two SBRs and the known PAO sequences. And sequences from the A/A-SBRwere less in each analogous OTU. For further analysis, the sequences in the databasewith100%similar with the sequences of the13OTU in A/A-SBR were searched toinfer the features and characteristics of phosphorus removal sludge of the A/A reactor.