Microbial Community Characteristics of a Completely Autotrophic Nitrogen Removal Over Nitrite(CANON)System Based on High-throughput Sequencing Technology

Research achievements regarding bacterial community dynamics of completely autotrophic nitrogen removal over nitrite(CANON) systems are helpful to improve the understanding of biological nitrogen removal processes and to better operation control.In this study,a lab-scale one stage nitritationanaerobic ammonium oxidation(Anammox) sequence batch reactor(SBR) was operated at 35 ℃ ±1 ℃under a regime of intermittent aeration.The full life cycle of a starting-up progress was studied,which covered a start-up phase,a quasi-steady-state phase and a final deterioration phase.High-throughput sequencing technology was employed to identify the microbial communities in different stages.The highest volumetric nitrogen removal rate of 218.0 mg/(L·d) was obtained after two weeks of start-up.16 S rDNA sequencing analysis revealed that the three functional bacteria took different proportions related to the total bacteria,i.e.,0.44% ,27.6% and 1.33% for anaerobic ammonium oxidation bacteria(AnAOB),ammonium oxidation bacteria(AOB) and nitrite oxidation bacteria(NOB) respectively.Anammox process occurred in the aeration phase due to the low dissolved oxygen,resulted in the gradual decline of the accumulated NO₂^--N at the end of the aeration phase.While at the last phase of the anoxic,AnAOB was suppressed for the depletion of NO₂^--N.At the end of the operating life cycle,Nitrosomonas established a stable foothold in the community(62% ),while the AnAOB species only occupied 0.13% ,which agreed well with the declined total nitrogen removal rate(19.3 mg/(L·d)).