Bacterial diversity and community structure of denitrifying phosphorus removal sludge in strict anaerobic/anoxic systems operated with different carbon sources

BACKGROUND: The effect of carbon source on the community structure of denitrifying phosphorus removal sludge has not yet been well established. In the current study, denitrifying phosphorus removal sludge with acetate, propionate and glycerol as the sole carbon source were acclimatized in three sequencing batch reactors (SBRs) under strict anaerobic-anoxic conditions, and sludge community structure was systematically investigated by high-throughput sequencing. RESULTS: Average effluent phosphorus concentrations were 0.79 mg L^-1, 0.37 mg L^-1 and 0.99 mg L^-1 for SBR fed with acetate, propionate and glycerol, corresponding to phosphorus removals of 82.5%, 91.8% and 79.2%, respectively. Seed sludge from a wastewater treatment plant had the richest microbial diversity, followed by glycerol based sludge; acetate and propionate based sludge exhibited similar diversity and community structure. From acclimation to stable period, Ca. Accumulibacter-like sequences increased from 4.54%, 4.38% and 1.57% to 9.53%, 41.5% and 7.96% for sludge with acetate, propionate and glycerol as carbon source. For glycogen accumulating organism (GAO)-like sequences, it varied from 1.54%, 2.22% and 1.18% to 6.92%, 1.18% and 1.79%, respectively. CONCLUSIONS: Propionate was a superior substrate favorable to the enrichment of phosphorus removal bacteria and elimination of glycogen accumulating bacteria in an anaerobic-anoxic system. Glycerol, a by-product of biodiesel, could be an alternative carbon source for denitrifying phosphorus removal.