Storage of acetate by denitrifying granular sludge under dynamic conditions in anoxic environment

In this study, the dynamic response of denitrifying granular sludge, cultivated in sequence batch reactor (SBR) under single anoxic condition, is described in terms of substrate (acetate) removal and storage and the transient response of storage and usage internal polymers were investigated with different substrate concentrations and COD:NO₃^--N (C/N) ratio. The results show that acetate was removed from the liquid phase by bacteria for energy needs or converting into storage as poly-β-hydroxybutyric acid (PHB). A trend of PHB content of denitrifying granular was observed that PHB concentration increased when substrate sufficient and then decreasing in the following substrate insufficient period. The Batch tests show that under different condition of C/N ratio was 5, the maximum (max.) synthesis rate of PHB changes from 0.37 gCOD/(g·h) to 0.44 CODg/(g·h), and the max. degradation rate of PHB was about 0.02 g/(g·h), and YSTOD changes from 0.25 to 0.35; under condition of C/N ratio was 7.5, the max. Synthesizing rate of PHB was about 0.36 g/(g·h) and YS_TOD changes from 0.38 to 0.45. The strongly storage ability could be achieved the advantage position in substrate competition.