Phosphorus removal performance and bacterial community structure of denitrifying phosphorus removal sludge operated with different carbon sources

In the present study, denitrifying phosphorus removal sludges with acetate, glycerol and propionate as the sole carbon sources were acclimatized in three sequencing reactors (SBRs) operated under strict anaerobic-anoxic conditions, and the sludges with different carbon sources were systematically investigated by high-throughput sequencing. Stable operation showed that propionate was the optimal carbon source, followed by acetate and glycerol, with average effluent phosphorus concentrations of 0.29, 0.79 and 0.98 mg/L, corresponding to removal rates of 93.4%, 82.5% and 79.2%, respectively. The seed sludge from WWTP had the richest microbial diversity, followed by sludge fed with glycerol, acetate and propionate. Moreover, the two Volatile Fatty Acids (VFAs) feeding sludge (acetate and propionate) exhibited similar bacterial diversity and community structure. At the class level, β-Proteobacteria was most abundant for all the sludge samples. At the order level, Rhodocyclales that most phosphorus removal bacteria belonged to was the most dominant order for the samples from SBRs. Sequence local BLAST (Basic Local Alignment Search Tool) showed that the Ca. Accumulibacter-like PAO abundances of sludge with propionate, acetate and glycerol as carbon sources were 41.5%, 9.5% and 8.0% respectively during the stable operation; propionate feeding sludge had the highest abundance. Compared with acetate and glycerol, propionate showed priority for the enrichment of phosphorus removing bacteria in anaerobic-anoxic system, and the best carbon source for the EBPR.