Metagenomic insights into mechanisms of nitrogen removal by heterotrophic nitrification-aerobic denitrification process under high ammonia stress Raw sequence reads

Heterotrophic nitrification-aerobic denitrification (HN-AD) process demonstrates strong potential for treating ammonia nitrogen (NH4+-N) wastewater. Nonetheless, the effect of high ammonia stress on the HN-AD process remains unclear, which restricts its engineering application. Herein, the HN-AD process was operated at different influent NH4+-N concentrations. HN-AD bacteria may enhance the removal of NH4+-N, total nitrogen, and chemical oxygen demand in the reactor by efficiently utilizing organic carbon sources for ammonia assimilation. Metagenomic analysis revealed that abundant taxa such as Pseudomonas and Halopseudomonas were highly tolerant to the high NH4+-N environment and formed a dense collaborative-competitive network within the reactor, which enhanced and maintained efficient NH4+-N removal.