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.