Abstract
To investigate the chief reason for phosphorus uptake by microorganisms affected by substrates in sequencing batch reactors with the single-stage oxic process, two typical substrates, glucose (R1) and acetate (R2) were used as the sole carbon source, and the performances of phosphorus removal and the changes of intracellular storage were compared. The experimental results showed that the phenomenon of excess phosphorus uptake was observed in two reactors, but bacteria’s capability to take in phosphorus and its intracellular storage were obviously different under the same operational condition. After steady-state operation, total phosphorus (TP) removed per MLVSS in R1 and R2 was 6.7–7.4 and 2.7–3.2 mg/g, respectively. The energy storage of poly-β-hydroxyalkanoates (PHA) was nearly constant in R1 during the whole period, and another aerobic storage of glycogen was accumulated (the max accumulation of glycogen was 3.21 mmol-C/g) when external substrate was consumed, and then was decreased to the initial level. However in R2, PHA and glycogen were both accumulated (2.1 and 0.55 mmol-C/g, respectively) when external substrate was consumed, but they showed different changes after the period of external consumption. Compared to rapid decrease of PHA to the initial level, glycogen continued accumulating to the peak (0.88 mmol-C/g) in 2 h of aeration before decreasing. During the aeration, the accumulations/transformations of internal carbon sources in R1 were higher than those in R2. In addition, obvious TP releases were both observed in R1 and R2 other than PHA and glycogen during the long-term idle period; moreover, the release content of phosphorus in R1 was also higher than that in R2. The researches indicated that different aerobic metabolism of substrate occurred in R1 and R2 due to the different carbon sources in influent, resulting in different types and contents of aerobic storage accumulated/translated in bacteria of R1 and R2. As a result, ATP content provided for phosphorus uptake was different in R1 and R2, and the capability to take up phosphorus was also different from each other.