The effect of pH shock on nitrogen removal performance of marine anaerobic ammonium-oxidizing bacteria (MAAOB) treating saline wastewater was studied by employing an ASBR reactor. Dynamic characteristics of the MAAOB were simulated by the Andrew model and Ratkowsky model. The results indicated that the reactor had the best nitrogen removal efficiency when the pH value was 7-8. The nitrogen removal rate (NRR) was (0.30±0.04) kg·(m3·d)-1, and the total nitrogen removal efficiency (TNRE) was (76.73±5.74)%. When the pH value was 8.5, FA had a mean concentration of 14.22 mg·L-1 and little effect on nitrogen removal. The NRR was (0.30±0.02) kg·(m3·d)-1. However, NO2--N accumulated and it was not completely removed. When the pH values were 6.5 and 9, the concentrations of FA were 0.22 mg·L-1 and 37.84 mg·L-1, respectively, the NRRs were (0.10±0.02) and (0.15±0.02) kg·(m3·d)-1, and the TNREs were (23.04±9.88)% and (42.12±5.52)%. The tolerance of the MAAOB in alkaline condition was stronger than that in acidic condition. The Andrew model was modified to determine the relationship between NRR and FA. Other parameters such as NRRmax, kS, and kI were also achieved simultaneously. These are key to describing the nitrogen removal process of MAAOB.
Keywords: biological nitrogen removal; kinetics; marine anaerobic ammonium-oxidizing bacteria (MAAOB); pH shock; saline wastewater.