The hydraulic characteristics of integrated cage denitrification bioreactor were investigated using pulse-stimulus response technique.The flow pattern of the bioreactor tended to be complete mixed flow with hydraulic retention time 4 h

superficial velocity 0.145 m·h-1

hydraulic load rate 6.0 m3·m-3·d-1.When it was simulated with tanks-in-series(TIS)model

N number was 1.55

1.56

1.54 and 1.55 at air flow rate 1.714

3.214

6.429

8.571 m3·m-3·h-1 respectively.When it was simulated by axial dispersion(AD)model

the corresponding Peclet numbers were 1.479

1.503

1.466 and 1.478 at air flow rate 1.714

3.214

6.429

8.571 m3·m-3·h-1respectively.The prediction of TIS model and AD model matched with each other.The mean value of total dead space of the bioreactor was 41.63%

and the hydraulic dead space was 21.99%.However

air flow rate had little effect on the hydraulic behavior of the bioreactor in this investigation.