Inhibition strategies of nitrite oxidation bacteria in biological nitrogen removal system: a mini review

In the partial nitrification and anaerobic ammonia oxidation (Anammox), it was necessary to control ammonia oxidation, aiming to inhibit the activity of nitrite-oxidizing bacteria (NOB) to achieve the accumulation of NO2--N. This review summarized methods of NOB inhibition which had been reported in the current literature. These methods included changing the dissolved oxygen concentration and sludge retention time, adjusting the free nitrite acid and free ammonia levels, adding chemical inhibitors such as hydroxylamine (NH2OH) and hydrazine (N2H4), and using other inhibition methods such as electromagnetic radiation and ultrasound. Most study revealed that NOB could be effectively inhibited by combining different inhibition methods and real-time control strategies. Concurrently, the utilization of biofilm and granular sludge and multi-bacterial cooperation processes associated with anammox and denitrification could reduce or eliminate the effect of NOB on the performance of the biological nitrogen removal system. This review aimed to provide valuable information for optimizing the biological nitrogen removal process to ensure highly efficient and stable operation.