Two SBRs which were under high ammonia loading[1 kg·(m3·d)-1] and different dual inhibition with feed-batch were employed to study how to control the stability of partial nitritation system. The experimental result showed that the dual inhibition of FNA and DO or FA and DO could implement partial nitrification process at 35℃±1℃ and the ammonia concentration of 1000 mg·L-1. The effluent NO2--N/NH4+-N ratio was about 1, and the effluent NO3--N concentration was close to 0, which was suitable for the appropriate influent for the ANAMMOX. In R1, under the dual inhibition of high FA and low DO concentration, the nitrite oxidizing rate was reduced from 28.16 mg·(g·h)-1 to 0.3 mg·(g·h)-1 (calculated as NO2--N, the same as below). The ammonia oxidizing rate decreased by 43.60%, which was stable at about 20 mg·(g·h)-1 (calculated as NH4+-N, the same as below). In R2,under the dual inhibition of high FNA and low DO concentration, the nitrite oxidizing rate reduced from 12.37 mg·(g·h)-1 to 0.02 mg·(g·h)-1. But the ammonia oxidizing rate remained at a higher level[45 mg·(g·h)-1]. Comparing the nitrification performance of the two SBRs under different control strategies, the dual inhibition of high FNA and low DO concentration had the advantages of short cultivation period, high biological activity and stable operation. It is therefore more suitable for the achievement of the partial nitrification.
Keywords: dual inhibition; free ammonia (FA); free nitrous acid (FNA); high ammonia nitrogen; partial nitrification; sequencing batch reactor (SBR).