Study On Microbial Characteristics And Biological Nitrogen Removal Function Gene In Anammox Reactor

Anaerobic ammonium oxidation(Anammox)is considered as a new biological nitrogen removal process with high efficiency and low consumption,and has been gradually applied in the biological nitrogen removal process of wastewater.In this study,the UASB and UASB-biofilm anammox reactors were started by seeding the activated sludge of the Wastewater Treatment Plant(WWTP),synthetic wastewater was used as influent.The microbial diversity high-throughput sequencing technology and metagenomic sequencing technology were used to sequence the seeding sludge and the anammox sludge from anammox reactors after start-up,respectively,to study the composition of the microbial community in the sludge samples and the Antibiotic Resistance Genes(ARGs)carried by it.At the same time,we will further discuss the biological nitrogen removal function genes in the sludge samples.The main research achievements of the thesis are as follows:(1)The UASB reactor and the UASB-biofilm reactor were successfully started up after 135 days and 126 days respectively,and both of them could operate stably.In the stable operation stage,NH₄⁺-N consumption:NO₂^--N consumption:NO₃^--N production(tri-nitrogen ratio)was close to tri-nitrogen ratio of 1:1.32:0.26 in the process of Anammox.(2)The results of metagenomic sequencing showed that the bacterial was the main microbial community in the seeding sludge and anammox sludge,the relative abundance was between 98.46%and 98.80%.The relative abundance of the archaea,the eukaryotic and the virus were all low.(3)The relative abundance of Nitrosomonas and Nitrospira decreased from 0.08%and 0.02%to 0.06%and 0.01%in the seeding sludge and UASB reactor anammox sludge,respectively.The denitrifying bacteria Denitratisoma and Arenimonas were enriched.Unclassified Crenarchaeotao and Nitrosopumilus belong to Ammonia-Oxidizing Archaea(AOA)were enriched,the relative abundance increased from 17.45%and 1.08%to 21.37%and 3.70%,respectively.A total of three Anaerobic Ammonium Oxidation Bacteria(AAOB)were detected,and the relative abundance of Candidatus Kuenenia increased from 11.45%to 97.27%.The relative abundance of Candidatus Brocadia decreased by 2.73%from 77.13%,and Candidatus Scalindua disappeared after culture.(4)Nitrosomonas and Nitrospira were detected in the anammox sludge of the two reactors.The dominant denitrifying bacteria are Arenimonas and Thermomonas,while the dominant AOA are unclassified Crenarchaotao.The dominant AAOB belong to Candidatus Kuenenia.(5)The types of antibiotics in the sludge samples were the same.The relative abundance of multidrug ARGs and peptides ARGs was the highest,24.84-29.69%and13.59-15.37%,respectively;The relative abundance of sulfadiazine ARGs and lincosamide ARGs was the lowest,0.87-1.01%and 0.35-0.71%.The subtypes of dominant antibiotic resistance genes in the seeding sludge and anammox sludge are basically the same.Among them,the relative abundance of mac B belonging to macrolide ARGs is the highest between 4.27%and 5.53%.The top ten ARGs subtypes in the seeding sludge were all enriched after the successful start-up of the anammox reactor.(6)There were six functional genes related to nitrification process were detected in the seeding sludge and anammox sludge,including amo A?amo B?amo C?hao?nxr A and nxr B;ten functional genes related to denitrification were detected,including nar G?nar H?nar I?nap A?nap B?nir K?nir S?nor B?nor C and nos Z.;Four functional genes in the anammox process were detected,the anammox functional genes hzs and hdh,It only exists in the two anammox sludges and the relative abundance is not much different,it is not detected in the seeding sludge.