Effect of Hydraulic Retention Time on Microbial Community Structure in Wastewater Treatment Electro-Bioreactors

The impact of hydraulic retention time (HRT) on the performance and microbial community structure of control and electro-bioreactors was investigated. Control bioreactors and electro-bioreactors were operated at HRT ranging between 6 and 75 h. The total bacterial counts in addition to the removal efficiency of NH4+-N, sCOD, and PO43--P was assessed in all the reactors tested. In addition, Illumina sequencing was performed to determine the microbial communities that developed in these reactors under each HRT condition. Phylogenetic analysis showed that Proteobacteria and Bacteroidetes were the dominant phyla in those reactors. In addition, Nitrospira sp. and Pseudomonas sp. were found to be present in electro-bioreactors with higher relative abundance than in control bioreactors. The results presented here are the first to determine what different microbial communities in wastewater electro-bioreactors due to the application of an electric current under different HRTs.