Intermittent aeration strategy to enhance organics and nitrogen removal in subsurface flow constructed wetlands

•Artificial aeration can greatly enhance oxygenation for nitrification in SFCWs.•Intermittent aeration developed alternate anaerobic and aerobic conditions in SFCWs.•Intermittent aeration simultaneously achieved high removal of COD, NH4-N and TN.

In this study, an intermittent-aerated subsurface flow constructed wetland (SFCW) A was set up to assess its performance in decentralized rural sewage treatment. A conventional SFCW B and a subsurface wastewater infiltration system (SWIS C) were also constructed for comparison. Alternate anaerobic and aerobic conditions were well developed by intermittent aeration. High removal of organic pollutants (29.3 g m−2 d−1), ammonium nitrogen (3.5 g m−2 d−1) and total nitrogen (3.3 g m−2 d−1) were obtained simultaneously in SFCW A compared with SFCW B and SWIS C. Fluorescence in situ hybridization analysis proved that the intermittent aeration obviously enhanced the growth of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in SFCW A. These results suggest that intermittent aeration strategy is reliable to enhance the performance of SFCWs in decentralized rural sewage treatment.