Novel insights into overcoming nitrite oxidation bacteria acclimatization problem in treatment of high-ammonia wastewater through partial nitrification

Abstract A partial nitrification sequencing batch reactor was operated to reveal mechanisms behind nitrite oxidation bacteria (NOB) acclimatization in high-ammonia wastewater treatment. The influent NH4+-N increased stepwise from 499.7±4.2 mg/L to 6994.5±7.5 mg/L with initial free ammonia (FA) concentration rising from 37.9±3.2 mg NH3-N/L to 715.3±47.3 mg NH3-N/L, respectively. NOB acclimatized this FA range with NO3--N production increasing from 29.2±2.6 mg/L to 144.1±31.0 mg/L in a cycle, which was caused by the shift of dominant NOB genus from Nitrospira to Nitrolencea. Nitrosomonas as ammonia oxidation bacteria, could sustain its activity of 62.1±0.1 mg NH4+-N/(gVSS∙L∙h) under the same condition. Hydroxylamine addition could be implemented as an emergency measure to alleviate NOB acclimatization in short-term operation. The findings expanded knowledge about NOB acclimatization types and provided novel insights for addressing this problem in a targeted way.