[Effect of different ratios of propionic to acetic acids on long-term cultured active sludge for enhanced biological phosphorus removal].

With the long-term cultured enhanced biological phosphorus removal systems in sequencing batch reactors, the effect of different ratios of propionic acid to acetic acid on the transformations of phosphorus and polyhydoxyalkanoates (PHA), and the metabolism stoichiometry of PHA by phosphorus accumulating organisms were studied in this paper. Results showed that the phosphorus removal efficiency improved with the increase of propionic acid to acetic acid ratio, and the suitable C-mol ratio of propionic acid to acetic acid was 2:1. Stoichiometry study indicated that 0.15 C-mol PHB and 0.33 C-mol (PHV + PH2MV) were synthesized per degraded C-mol acetic acid, and very few PHB and 1.21 C-mol (PHV + PH2MV) were synthesized per degraded C-mol propionic acid. It was also observed that the phosphorus removal efficiency exhibited a good linear relationship with (PHV + PH2MV).