The effects of aerobic starvation on nitrification bacteria's activity and sludge performance of filamentous bulking sludge were investigated in an aerobic-anoxic SBR process. Ammonia-oxidizing bacteria (AOB) had a higher hungry sensitivity than nitrite-oxidizing bacteria (NOB) in 14 days of aerobic starvation process which was kept aeration and without feed. The decay of AOB [(0.42±0.06) d-1] was higher than NOB [(0.34±0.05) d-1]. The phenomenon of nitrite accumulation was apparently achieved from the system in the early resuscitation period. This phenomenon was due to that AOB was able to keep their cells in a state of readiness where it was possible to start oxidizing ammonia almost immediately and with the maximum rate after shorter starvation periods. They were thereby able to respond rapidly to changing environmental conditions

which was reflected by the higher activity resuscitation rate of AOB than that of NOB. In addition

aerobic starvation could kill filamentous bacteria and improve the settleability of filamentous bulking sludge quickly. And sludge volume index (SVI) accordingly declined from 170 ml·g-1 to 30 ml·g-1. Extracellular polymeric substances (EPS) and soluble microbial products (SMP) could transform into each other and became the source of carbon and energy for hungry bacteria to guarantee cell maintenance in a long term starvation environment.