Short CommunicationMicrobial community analysis using MiSeq sequencing in a novel configuration fluidized bed reactor for effective denitrification

•A novel fluidized bed reactor can achieve high performance at low HRT of 50 min.•The COD: NO3−-N ratio of 3 indicated the highest COD and nitrate removal efficiency.•The ratio of COD: NO3−-N strongly influenced the composition of microbial community.

A novel configured fluidized bed reactor (FBR) with granular rubber as the fluidized media was operated without internal recirculation to achieve denitrification. This FBR could operate under a low hydraulic retention time (HRT) of 50 min due to the low rubber media density and absence of recirculation. Synthetic nitrate-rich wastewater with a fixed nitrate (NO3−-N) concentration and varying COD concentrations was fed into the FBR. The nitrate removal profile showed a rapid nitrate reduction at the bottom of the reactor with a high performance under the low HRT. Different microbial communities were identified using Illumina Miseq sequencing. The dominant microorganisms belonged to the Beta- and Gamma-proteobacteria classes and played important roles in nitrate reduction. Acidovorax was abundant at low COD: NO3−-N ratios, while Rhizobium and Zoogloea were dominant at high COD: NO3−-N ratios. The COD: NO3−-N ratio strongly influenced the composition of the microbial community including the dominant species.