Effects of P/C ratios on the growth, phosphorus removal and phosphorus recovery of a novel strain of highly efficient PAO

Abstract

The growth and metabolism of polyphosphate accumulating organisms (PAOs) affect the phosphorus (P) removal performance of the biofilm sequencing batch reactor (BSBR). A novel strain PAO Acinetobacter lwoffii (P5) was isolated and identified from the BSBR. The growth conditions of P5 in BSBR were simulated with alternate aerobic (9 h)/anaerobic (6 h) cycles for 10 days. The orthogonal experiment showed that P and carbon (C) sources had significant interactions with the growth and P metabolism of P5 (P >0.05). The growth of P5 was mainly affected by the C source, but its P metabolism was mainly affected by the P source. Metabolism model, enzyme activity, and P recovery efficiency tests showed that when the sludge loading was 0.15 g P/(gMLSS·d), the P recovery efficiency was the highest (82.07 %). When the P/C ratio was ≥1/40, the P removal activity was activated, and the P removal performance of P5 was improved by the polyphosphate-accumulating metabolism (PAM). When the P/C ratio was ≤1/100, the P removal activity was inhibited, and the P removal performance of P5 was decreased by the glycogen-accumulating metabolism (GAM). Our research on the P mechanism of P5 provided valuable in-depth insights into the P removal performance of PAOs.