Microbial similarity and community structure of phosphorus removal sludge with different electron acceptors

Phosphorus removal sludge with nitrate, nitrite and oxygen as the sole electron acceptor were acclimatized in three parallel sequencing batch reactors, namely R_N03, R_N02 and R₀₂ respectively. Operation results showed that phosphorus removal rates were 84.8%, 87.4% and 78.7% on average for R_N03, R_N02 and R₀₂, with effluent TP concentration of 0.758 mg/L, 0.931 mg/L and 0.632 mg/L. High-throughput technology was employed to evaluate the microbial similarity and community structure of phosphorus removal sludge with different electron acceptors. Results indicated that denitrifying phosphorus removal sludge with nitrate and nitrite as electron acceptors exhibited similar bacterial community structure and was distinct from that of aerobic phosphorus removal sludge. The dominant microbial organisms were clustered into five clades based on the phylogenetic relationship of the significant OTUs sequences. Through sequence BLAST, 0.716%, 1.78%, 2.53% and 4.80% of sequences from Seed, R_N03, R_N02 and R₀₂ could be assigned to Accumulibacter-like sequences at similarity level of 97%; 0.368%, 1.44%, 1.32% and 30.9% of sequences could be assigned to GAO-like sequences, indicating that alternating anaerobic-anoxic condition was favorable toward elimination of GAO. Moreover, potential public health hazard was revealed for nitrite based denitrifying phosphorus removal sludge.