Short-cut nitrification and denitrification phosphorus removal has the advantages of low oxygen consumption

low carbon source demand

and low sludge yield

but aerobic granular sludge (AGS) is prone to disintegration and instability due to large particle size. In order to solve the problem of instability and ensure sufficient anoxic zone for denitrifying phosphate accumulating organisms (DPAOs)

long-term cultivated granular sludge with artificial water distribution was used as seed sludge

and the particle size distribution was regulated by optimizing hydraulic shear strength

so as to realize the stable operation of domestic sewage treatment and explore the influence of hydraulic shear strength on particle structure. Results showed that the particle size range with optimal simultaneous nitrogen and phosphorus removal performance and dense particle structure was 800-1 400 μm. By adjusting the hydraulic shear strength to 1 435.2

the proportion of particles in this size range was increased to 53.39%. When the granulation reached stable

the effluent COD concentration was maintained below 50 mg/L

the TN removal rate was about 90%

the effluent TN concentration was 4.28 mg/L

the average removal rate of TP was 93.45%

and the effluent TP concentration was below 0.5 mg/L. In addition

the analysis of extracellular polymeric substances (EPS) by excitation-emission matrix (EEM) combined with parallel factor (PARAFAC) showed that increasing hydraulic shear strength could reduce the content of humic acid and increase the proportion of protein

which was conducive to optimizing particle sedimentation performance and improving compactness. By optimizing the particle size range

the larger anoxic zone of granules could be used to enrich DPAOs and gradually eliminate nitrite oxidizing bacteria

avoiding the expansion of filamentous bacteria

and realizing stable short-cut nitrification

denitrification

nitrogen

and phosphorus removal of domestic sewage.