Nitrogen metabolism functional shifts of indigenous bacteria and effect on nitrogen removal in microalgae-based municipal wastewater treatment system across aeration modes.

Although the effect of aeration intensity on the performance of microalgae-based wastewater treatment systems has been widely studied, the impact of aeration mode has received less attention. This study explored how different aeration modes influence nitrogen metabolism in microalgae-based wastewater systems using metagenomic analysis. Both continuous aeration (CA) and intermittent aeration (IA) supported rapid bacterial growth and effective pollutant removal. Compared to CA, IA and no-aeration modes significantly enhanced bacterial nitrification and denitrification. Key nitrogen-metabolizing genera such as Paracoccus, Acidovorax, and Rhizobium played major roles in nitrogen cycling. Their abundances were closely associated with NH-N, NO-N, NO-N, total phosphorus, chemical oxygen demand, dissolved oxygen, bacterial number, and total biomass. Overall, environmental changes induced by different aeration modes significantly shaped indigenous bacterial communities involved in nitrogen metabolism, thereby influencing the abundances of nitrogen metabolism-related genes and, ultimately, nitrogen removal performance.