Long-term starvation and subsequent reactivation of a high-rate partial nitrification activated sludge pilot plant

► The effect of long-term starvation over a partial nitrification system was examined. ► The best conditions to maintain the ammonia oxidizing bacteria were anoxic. ► The automatic control loop of inflow allowed a fast recovery of the starved system. ► Fast and full recovery of the nitrifying activity was achieved in only 5 days.