Characterization of microbial community structure of anaerobic baffled reactor-integrated oxidation ditch-biological aerated filter for landfill leachate treatment

To provide microbial evidence for technique improvement of anaerobic baffled reactor (ABR) - integrated oxidation ditch - biological aerated filter (BAF) combined processes for landfill leachate treatment, microbial community structure of the treatment system under different recycle ratios were investigated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) combined with sequencing and phylogenetic analysis. The results indicated that, under high recycle ratio, microbial community structure changed slightly along with reactor and running time, and microbial community diversity in the anaerobic part of ABR had no significant change, but reduced in the anoxic part of ABR, oxidation ditch and BAF with the increase of recycle ratio. Sequencing results revealed that there may be other denitrification modes of autotrophic denitrification and anaerobic ammonia oxidation in ABR besides conventional biological denitrification. It concluded that the systemic population diversity indexes decreased, and the phase separation of acidogenesis and methanogenesis was destroyed longitudinally down the ABR with high recycle ratio, which illustrated the decrease of running stability of the treatment system. The results provide some valuable references for design and operation of the treatment system.