Domestication Of Denitrifying Phosphorus Removal System And The N < Sub > 2 < / Sub > O Emissions Research

The new biological denitrifying dephosphatation technology based on DPB is the hotspot and focus in domestic and overseas wastewater treatment research field. This technology overcame many problems exposed in traditional sewage nitrogen phosphorus removal process,such as saving area and infrastructure expenses (anoxia denitrification reactors and anaerobic release phosphorus reactors combined together), reducing energy consumption (phosphorus uptake by anaerobic instead of anoxia), improving carbon sources utilization (one carbon amphibious), decreasing the sludge output (DPB instead of two kinds of bacteria denitrifying bacteria and phosphorus enrichment bacteria), etc. This technology showed broad application prospect in wastewater treatment field in recent years. But DPB belonged to denitrifying bacteria after all, and denitrifying bacteria all produced N2O, so this technology could not miss facing the potential N2O emission problems in application processes.The contents of this paper contained three parts. Firstly, compared the influence of different technology on the domestication of denitrifying phosphorus removal system. Secondly, studied the effect of different C/N on N2O emissions in denitrifying phosphorus removal system.Thirdly, Screened DPB from the denitrifying phosphorus removal system, and studied their biological characteristics.The conclusions of the research for three years were as follows:(1) High and stable nitrogen and phosphorus removal efficiency sludges were domesticated by A/A/O and A/A, and it is proved that two methods were both available domesticated ones. In the same condition, A/A/O system which had better nitrogen and phosphorus removal efficiency in the beginning started up before A/A, phosphorus and nitrogen removal efficiency of A/A system increased significant in the middle stage.Finally, two systems both got to stable nitrogen and phosphorus removal efficiency with no significant differences, visible system of aerobic phase added may accelerate denitrifying dephosphatation system startup. By different domesticated mode,the same kind of actived sluge achieved the same nitrogen and phosphorus removal effeciency, with obviously different microbial community structure. (2) The trial also researched nitrogen and phosphorus removal rate and their influence on N2O emissions under different C/N in COD150and300mg.L-1conditions. The results were total nitrogen and phosphorus removal rise, N2O-N in the proportion of total nitrogen removal drop,with the increase of C/N. In the same C/N condition,compared with low concentration COD (150mg.L-1),high COD (300mg.L-1) total nitrogen and phosphorus removal rate raised, N2O-N in the proportion of total nitrogen dropped.The study designed C/N for three concentration as5,7.5,10,with300mg.L-1COD, which leaded that TP removal effeciency of system were69.64%,81.30%and84.10%respectively, TN were78.24%,84.07%and89.95%,N2O-N in the proportion of TN were0.22%,0.11%and0.05%, respectively. For the conditions of150mg.L-1COD, C/N were for3.75,5and10,the removal rate of TP were24.81%,53.19%and67.61%, the removal rate of TN were18.10%,43.69%and72.94%, N2O-N in the proportion of TN were8.94%,2.33%and0.15%,Respectively.(3) The research got21separable pure strains, and screened three DPB named DPBA511、DPBA9, DPBA10from them by denitrification medium,metachromatic granules, PHB staining experiments,and nitrogen and phosphorus removal efficiency test.Three DPB all contained PHB and metachromatic granules, and had more than50percent of nitrogen and phosphorus removal efficiency in given medium. By morphological, physiological,biological characteristics and16S rDNA sequence analysis, it is found that DPBA511and Dechloromonas aromatica in β-proteobacteria had97%similarity, DPBA9and Candidatus Accumulibacter phosphatis clade IIA str. in β-proteobacteria had97%similarity too, DPBA10and Bacillus pumilus had99%similarity.