Free ammonia shock suppression combined with sludge retention time control to achieve high-efficiency short-cut nitrification
Maintaining the activity of ammonia-oxidizing bacteria(AOB)while inhibiting the activity of nitrite-oxidizing bacteria(NOB)in the activated sludge system is the key to achieve short-cut nitrification.Therefore,a method of free ammonia(FA)shock suppression combined with sludge retention time(SRT)control was put forward to achieve efficient and consistent short-cut nitrification.Only FA shock suppression for 1 d could achieve rapid start of short-cut nitrification,but could not maintain for long term.Then,the SRT was controlled at 10 and 20 d,and the result showed that SRT of 20 d was better to achieve efficient and consistent short-cut nitrification.The high-throughput results reflected that FA shock suppression combined with SRT control achived efficient ammonia oxidation because Nitrosomonas occupied the dominant position all the time.