In order to explore the stability of the completely autotrophic nitrogen removal over nitrite (CANON) process and the setting of related parameters in the intermittent starvation based on hydraulic screening

sequencing batch reactor (SBR) was used for the CANON process. Flocculent sludge was periodically discharged through hydraulic screening

and intermittent starvation was performed on it to inhibit the growth and reproduction of nitrite-oxidizing bacteria (NOB). The adjustment of two parameters (sedimentation time and starvation period) was investigated to realize the stable operation of CANON process. Experimental results show that sedimentation time had great impact on the particle size distribution and functional bacteria activity. A sedimentation time of more than 1.5 min could basically retain the ANAMMOX bacteria in the reactor. Ammonia-oxidizing bacteria (AOB) were distributed in flocculent sludge and granular sludge

and NOB was mainly distributed in the flocculent sludge with low mass transfer resistance. The activity decay rate of AOB during hypoxic starvation remained basically stable

while NOB was more sensitive in the face of hypoxic starvation

and the activity decay rate of NOB was greater than that of AOB. In the recovery phase

since AOB has a unique mechanism to deal with starvation that it can keep the cells in a state of oxidizing NH+4-N at the maximum rate immediately after experiencing a short-term starvation

it could reach the substrate degradation rate of 0.097 g/(g·d) when the inlet water has been fed for 3 d

which was 86% of the pre-starvation rate. However

NOB could not quickly adapt to the changes in the environment

causing its activity recovery rate to lag behind AOB. When the reactor was operated in the mode of 4 d starvation and 3 d recovery

NOB was effectively suppressed that the NO-3-N in the effluent showed a downward trend. Afterwards

the intermittent starvation period was adjusted to 4 d starvation and 5 d recovery

which improved the activity of AOB and the treatment effect was further enhanced. Entering the stable stage

the average values of effluent NH+4-N and NO-3-N were 2.69 and 7.79 mg/L respectively

and the removal rates of ammonia nitrogen and total nitrogen reached 96% and 79% respectively. The use of hydraulic screening and intermittent starvation CANON process to treat low-ammonia nitrogen wastewater has stable operation performance

and the effluent meets the first-level A standard specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918—2002).