Study On Denitrifying Polyphosphate-accumulating Organisms And Denitrifying Phosphorus Removal Process

Water pollution and eutrophication were caused by emissions of excessive nitrogen and phosphorus. It was great significance to study the mechanism of nitrogen and phosphorus removal. The purpose of this dissertation was to investigate the biological characteristics of denitrifying polyphosphate-accumulating organisms. And nitrogen and phosphorus removal of A / O / A SBR process, which was a novel nitrogen and phosphorus removal process reactor, has been studied, aiming at providing sound technique support for its application.6 denitrifying phosphate-accumulating organisms (DNPAOs) were isolated using the special medium from the anaerobic/aerobic/anoxic SBR reactor. And the most efficient DNPAO, which was called Q-hrb05, was screened by a phosphate uptake experiment. What was more, the physio- biochemical characterization, inspection of the poly-P. Strain analysis and 16S rDNA molecular identification were performed. And the accession number of 16S rDNA gene sequence of strain Q-hrb05 in GenBank is GU214826. The result showed that strain Q-hrb05 belonged to Bacillus sp., which homology can reach to 99%. The phosphorus uptake rate of strain Q-hrb05 was averaged at 85% within 12 hours, and it has the denitrification capacity in the aerobic condition. It can be found that the phosphorus uptake rate is related to changes with the content of PHB. Under anaerobic condition, the maximal P-release rate was 66%, which can reach to 12% of the dry cell weight. The P-uptake rate is 92% with the decreasing content of PHB.Effects of different pH values, carbon source, C/N ratios of flow on nitrogen and phosphorus removal and the microbial population variation of A/O/A SBR process were investigated by using synthetic domestic wastewater as feed. The results showed that the highest nitrogen and phosphorus removal efficiency was achieved, when pH, carbon source, C/N ratio were kept as 7.5, Acetic acid and 1.4, respectively. The average phosphorus removal rate was about 97.28%, and the denitrification rate reached 99.5%. In addition, the dynamic change of microbial population was consistent with the variation of inflow. Abundance of the microbial populations changed a little, but the succession of structural dynamics of microbe appeared. When the reactor was running well, uncultured chlorobi bacterium was enriched in the system, and it might be the major denitrifying phosphate accumulating microorganisms (DPAOs) in the system. Dynamics of functional microbiology community variation was also analyzed by FISH technique. With the domestication of time, the number of phosphorus removal bacteria and denitrifying bacteria in the system increased significantly. That result showed that A/O/A SBR provided suitable conditions for the growth and metabolism of function bacterial.