Removal of nitrogen and organic matter in an intermittently aerated horizontal subsurface flow constructed wetland

The objective of this work was to evaluate the effect of intermittent aeration on the removal of ammonium (NH4+), total nitrogen (TN) and chemical oxygen demand (COD) in a horizontal subsurface flow constructed wetland (HFCW). Two HFCWs were studied, one non-aerated and another aerated intermittently, and both cultivated with Typha latifolia. Each system received 8.6 L day-1 of synthetic wastewater, resulting in 3 days of hydraulic retention time. The two systems displayed high efficiencies in the removal of COD (>90%); however, the intermittently aerated HFCW showed a higher rate of COD removal. Additionally, the removal of TN (48.8%) and NH4+ (57.7%) in the non-aerated system was limited, while in the aerated system, the efficiencies of TN (81.2%) and NH4+ (98.6%) removal were satisfactory. Thus, the results indicate that via intermittent aeration, nitrification and denitrification occur simultaneously, improving the performance of HFCW in the removal of TN and NH4+.