Study On Performance And Microbial Characteristics Of Co-existence Of Anammox And Denitrification For Simultaneous Nitrogen Removal

The co-existence of anaerobic ammonium oxidation（Anammox）and denitrification can not only remove organic matter but also improve TN removal efficiency.It’s regarded as a cost-effective and energy saving way for low C/N ratio wastewater treatment.The aim of this study was to 1)enrich anammox bacteria;2)enrich denitrifying bacteria by adding organic matter to the anammox system in order to explore the effect of C/N ratio and carbon sources on the coupling process of anammox and denitrification;3)analyze the microbial community by Illumina high-throughput sequencing in order to reveal the variation of dominant bacteria.An UBF reactor was adopted to enrich anammox bacteria successfully.The volume loading of upflow blanket filter increased from 0.52 kg·（m³·d）^-11 to 2.75 kg·（m³·d）^-11 by improving the influent NH₄⁺-N and NO₂^--N concentrations.The removal efficiencies of NH₄⁺-N,NO₂^--N and TN increased from76.18%,53.47%,55.66%to 94.04%,86.97%,82.96%respectively.Meanwhile,Brocadiacea increased from 0.0746%to 24.5727%and became the dominant bacteria.It indicated that anammox bacteria was enriched successfully.Organics was addded to the anammox system to achieve the co-existence of anammox and denitrification.The optimal nitrogen removal of above 96%was achieved at the glucose concentration of 56.4 mg L^-1（TOC/N ratio of 0.1）.With increasing influent glucose,the anammox activity was deteriorated and the contribution made by anammox process to nitrogen removal decreased from 88.4%to 37.9%,while the contribution made by denitrification process to nitrogen removal increased from 2.9%to 62.1%.The ammonium removal efficiency and TN removal efficiency at the influent gucose of 374.9 mg L^-11 were decreased to around 10%and 55%,respectively.The influent nitrite to ammonium ratio of0.95¹.40 would not obviously affect the nitrogen removal due to the co-existence of anammox,denitrification and partial denitrification.The glucose could achieve the co-existence of anammox and denitrification and improve the nitrogen removal efficiency.However,the sodium acetate has a little influence on the nitrogen removal,and the sodiumpropionate was not profitable for nitrogen removal.The evolution process of the dominant bacteria was revealed by Illumina high-throughput sequencing.The microbial community in R1 was similar with that in R2.The main genera in R1 and R2 were Candidatus Kuenenia、Hydrogenophaga、Bdellovibrio、Diaphorobacter、Flavobacterium、Pseudomonas and Rubrivivax.The predominant genus changed from Candidatus Kuenenia to Diaphorobacter with the addition of glucose and then changed to Hydrogenophaga with the decrease of glucose.It indicated that organics concentration had an effect on the microbial communities.