Study On Quick Start-up Of ANAMMOX Process And Characteristics Of Microbial Community Based On AMBR

Anaerobic ammonia oxidation?ANAMMOX?is a new and efficient biological nitrogen removal technology.The coupling nitrogen removal process based on ANAMMOX has been gradually applied from laboratory to field.It has also owed remarkable economic and environmental benefits.However,the slow growth rate of ANAMMOX bacteria and rigorous survival condition usually resulted in long start-up cycle of ANAMMOX reactor,especially the rapid start-up of ANAMMOX reactor with different field application,which directly limited the Large-scale application of ANAMMOX process.In view of this,based on anaerobic membrane bioreactor?AMBR?,this study investigated the quick start-up performance of ANAMMOX from two aspects:the structure of reactors and the selection of Inoculated sludge.Moreover,Miseq High-throughput sequencing technology was used to analysis the microbial community dynamics of different inoculated sludge from the molecular biology perspective,which provided macro and micro basis for the selection of sludge source for quick start-up of ANAMMOX reactor and promoted the engineering application process of ANAMMOX.The main conclusions of the study are as follows:?1?In order to study the quick start-up process of anaerobic ammonium oxidation?ANAMMOX?,two types of reactors with different hydraclic flow state inoculated with aerobic nitrifying sludge were investigated,the membrane bioreactor?AMBR?and anaerobic baffled reactor?ABR?,respectively.The result showed that both reactors successfully started up ANAMMOX process.The start-up period of the AMBR?90d?was 20%shorter than the ABR?111d?,During the stable operation,the average nitrogen?NH₄⁺-N+NO₂^--N?removal capacity of 0.098 kg·?m³·d?^-1in the AMBR was also higher than that of 0.089kg·?m³·d?^-1 in the ABR.In addition,the differences of sludge morphology were obvious in the two reactors;flocculent sludge was developed in the AMBR while ANAMMOX granular sludge was mainly formed in the first compartment of the ABR.Moreover,the quantitative relationship analysis between NH₄⁺-N,NO₂^--N and NO₃^--N showed that the AMBR system contains more kinds of nitrogen removal functional bacteria,compared to the ABR,is conducive to the removal of nitrogen.AMBR exhibited a more excellent performance for ANAMMOX start-up.?2?In order to get the optimal sludge source of anaerobic ammonium oxidation?ANAMMOX?and the rapid formation of ANAMMOX granular sludge,two same CAMBRs?combined ABR and AMBR?were compared for ANAMMOX enrichment with different inoculated sludge,the anaerobic granular sludge?R1?and flocculent denitrifying sludge?R2?.The result showed that the ANAMMOX was successfully initiated after 45d and 60d in both reactors,respectively.The enrichment processes could be divided into three different phases,which were lag phase,activity elevation phase and stationary phase,but the removal rules of nitrogen in each phase were different.In the steady phase,the average removal rates of NH₄⁺-N and NO₂^--N were higher than 95%.In addition,the red ANAMMOX granular sludge with main diameter of 0.8¹.6mm was formed in the R1 while flocculent sludge and irregular block with low degree of granulation was mainly developed in the R2.The phenomenon of red granular sludge floating in the two reactors could also be observed.Moreover,the quantitative relationship analysis between NH₄⁺-N,NO₂^--N and NO₃^--N showed that there may be nitrate-dependent ANAMMOX,which resulted in the oxidation of excess ammonia,and the typical nitrite-dependent ANAMMOX was occurred in the R2.?3?In order to identify the characteristics of microbial community of different inoculated sludge in the before and after of the rapid start-up of CAMBR ANAMMOX reactors from the molecular level,Miseq High-throughput sequencing technology was applied to this study.The results of ACE,Chao,Shannon and Simpson index showed that when compared with the inoculated sludge,the species abundance in R1 reactor increased greatly during the stable operation period.But its bacterial diversity changed little.While the microbial abundance and diversity in the R2 reactor were significantly lower than the starting level of vaccination.The dominant bacteria at a phylum level were mainly consisted of Proteobacteria?Chloroflxi?Bacteroidetes and Planctomycetes,among which the abundance of Proteobacteria and Planctomycetes belonged to denitrifying bacteria was significantly higher than those of inoculated sludge.After 100 days of cultivation,the genera of Candidatus Brocadia and Candidatus Jettenia in the phylum Planctomycetes were detected in both R1 and R2.Furthermore,Candidatus Brocadia was the leading genera in the phylum Planctomycetes,and the percentages of the microbial populations in the sludge was 12.68%and 3.50%,respectively,while the genera of Candidatus Jettenia only accounted for 0.085%and 0.42%.In addition,the system also detected other denitrifying bacteria genus,such as Nitrosomonas,Denitratisoma,Thiobacillus,Arenimonas,Limnobacter,Thermomonas,Comamonasand Hyphomicrobium.It is worth noting that the genera of Denitratisoma is larger and higher in both reactors,and its abundances were 12.34%and 8.87%,respectively.