The process of starting AAOB granular sludge under low temperature substrate (NH+4-N

NO-2-N (40±10) mg/L) was investigated. In this study

SBR reactor was used to gradually shorten the experimental cycle to start AAOB granular sludge

and the nitrogen removal rate and nitrogen load of the system were analyzed for the kinetic characteristics of anaerobic ammonium oxidation process at each stage. Meanwhile

the granular sludge morphology

average particle size

EPS content

and three-dimensional fluorescence characteristics of EPS were analyzed. Results showed that the experimental period was shortened (24 h→12 h→10 h→8 h)

and the nitrogen load increased from 0.074 g/(L·d) to 0.204 g/(L·d). The Grau second-orders model better characterized the process of starting AAOB granular sludge. The matrix removal rate constant k2 increased from 0.15 to 0.22

and the denitrification performance was gradually improved. The MLSS and MLVSS of the sludge were finally stabilized from 2 989 and 2 348 mg/L to 2 460 and 1 776 mg/L. As the reaction went on

the anaerobic ammonium oxide sludge fully utilized the matrix

and the granular sludge was gradually stabilized. The average particle size of the particles reached 410 μm. The PN content and the PN/PS value first increased and then tended to be stable

and they became larger as the particle size increased. The three-dimensional fluorescence component in the sludge EPS was analyzed by the PARAFAC method

which was composed of NADH

riboflavin

and humic acid.