The prevention process of anammox inhibited by nitrite: cannot by change the external conditions, turning inward to enhance the antifragility of anammox bacteria

Abstract

Abstract To minimize the effect of nitrite inhibition and increase the antifragile of anammox reactor, exposing partially sludge to high nitrite in a side-stream unit to enhance nitrite tolerance of anammox sludge. In this study, anammox reactor with the side-stream unit reduced by 56.04% in nitrogen removal rate (NRR) with initial 30 mg·L-1 nitrite exposure, while increased 33.3% with later 100 mg·L-1 exposure. The sludge subjected to nitrite exposure exhibited enhanced levels of tolerance, with the specific anammox activity (SAA) was 16.81 times higher compared to the non-exposed sludge. The NRR decrease rate of reactor equipped with side-stream unit was twice times slower to response nitrite shock. After nitrite exposure, the dominant anammox bacteria shifted to Candidatus Jettenia. BugBase predicted functional results suggest that anammox sludge may adapt to nitrite by reducing potentially pathogenic. In conclusion, a novel strategy for enhancing operational stability of the anammox system was proposed.