[Nitrite Regulation During Start-up of Combined Partial Nitritation and ANAMMOX Process].

Two types of full-scale reactors(SBR, 116.6 m, activated sludge process; SBBR, 64.8 m, activated sludge and biofilm process) were inoculated with activated sludge from a swine wastewater treatment plant. The effect of NO-N concentration on ANAMMOX was investigated in the reactors during the start-up of the combined partial nitritation and ANAMMOX(CPNA) process by controlling the dissolved oxygen(DO), aeration mode, and NaNO dosing. The results showed that the SBBR was more suitable for rapid start-up of partial nitritation under the same operation conditions. Despite NO-N inhibition(100-129 mg·L, 7 days), the ANAMMOX process was successfully started by the SBR on day 39, and the total nitrogen removal rate and efficiency(TNRR and TNRE) were 0.069 kg·(m·d) and 23.3%, respectively. However, 17 days of NO-N inhibition(129-286 mg·L) had an unrecoverable effect on ANAMMOX activity in the SBBR. By adding NaNO, the SBR successfully started the CPNA process on day 77. The TNRR, TNRE, and activity of ANAMMOX from day 51 to 77 increased rapidly from 0.070 to 0.336 kg·(m·d) , 16.0% to 52.2%, and 0.012 to 0.307 kg·(kg·d) , respectively. The gene copy concentration of AOB and ANAMMOX bacteria in the SBR increased from the original 8.06×10 and 4.42×10 copies·mL to 1.02×10 and 1.77×10 copies·mL, respectively, which indicated that the rapid enrichment of AOB and ANAMMOX bacteria in the SBR was achieved mainly by controlling DO, aeration mode, and NaNO dosing. Reasonable nitrite regulation is the key for the start of the CPNA process.