An effective strategy for rapid nitrite accumulation related to quorum sensing and the impact of quorum quenching enzyme

Abstract

Nitrite accumulation is crucial in nitrogen removal processes that treat wastewater with a low carbon-to-nitrogen (C/N) ratio. This study investigates the effectiveness of effluent reflux in accelerating nitrite accumulation, considering quorum sensing, and explores the impact of quorum quenching enzymes. The results demonstrate that effluent reflux successfully accelerates the nitrite accumulation rate to 92.2% and increases the abundance of Nitrosomonas from 0.2% to 19.5%, as well as hydroxylamine oxidoreductase (HAO) from 0.285 Eu g−1 SS to 0.475 Eu g−1 SS. The quenching enzyme suppresses the growth of aerobic ammonia-oxidizing bacteria, leading to a decrease in Nitrosomonas abundance to 4.2% and HAO to 0 Eu g−1 SS. However, it enhances denitrification, which consumes nitrite and results in the deterioration of nitrite accumulation. Consequently, the total nitrogen (TN) removal efficiency increases from 15.5% to 43.2%, and the abundance of Hyphomicrobium increases to 33.7% accordingly. Quorum sensing proves to be an effective strategy for regulating ammonia removal and nitrite accumulation, and effluent reflux has a positive effect on enhancing quorum sensing.