Effect of backwashing on the microbial community structure and composition of a three dimensional particle electrode coupled with biological aerated filter reactor (TDE-BAF)

The impact of backwashing on recovery capacity and microbial diversity of the TDE-BAF by comparing with single BAF was investigated. Results showed that the effluent concentrations of CODcr, TOC, NH4+N and Turbidity after backwashing all revealed initial peak and gradually decreased to a steady state. TDE-BAF has a slightly better backwashing recovery capacity than single BAF. Regarding to backwashing recovery of CODcr, TOC, NH4+N and Turbidity, TDE-BAF needs approximately 4 h, 3 h, 2 h, 4 h, however, single BAF spends around 6 h, 4 h, 3 h, 5 h, respectively. Miseq pyrosequencing was used to investigate microbial diversity of TDE-BAF. The microbial community structures at phylum level were different between TDE-BAF and single BAF. Flavobacterium, Methylophilus, Saprospiraceae_uncultured, Sphaerotilus, Prosthecobacter and Comamonadaceae_unclassified were ubiquitous and distinct phyla. The diversity of the microbial community in the upper part of two reactors greatly raised from before-backwashing to after-backwashing biofilm samples, but in contrast it decreased on the lower part of two reactors. The microbial community structures at genus level were different between TDE-BAF and single BAF. The relative abundance of after backwashing in the TDE-BAF indicated that most genus in the upper part gradually rose, while the majority of genus is decreased rather than increased in the lower part.