Influence of aeration on nitrogen removal of constructed wetlands

Six groups of integrated vertical flow constructed wetlands were used in this paper. Three combinas of Acorus gramineus and Caldesia reniflrmis; Sagittaria sagittifolia and Softstem bulrush; Junous effuses and Pontederia cordata are planted on the down/up pool respectively, and the corresponding aeration combinations were set as well. The effects of aeration treatment on removing nitrogen in the landscape water of integrated vertical flow constructed wetland were tested. All the treatments were conducted in the condition of artificial climate chamber. The result showed that the treatment of aeration in different combination of plants could improve the removal effect of ammonia and nitrite nitrogen in wetland, and among all, the combination of Acorus gramineus and Caldesia reniflrmis resulted the highest removal efficiency of ammonia, which reached 84.88% while the combination of Junous effuses and Pontederia cordata made the highest removal efficiency of nitrite, which was about 94.91%. But the treatment of continuous aeration was not benefit to remove nitrate and even would result in the enrichment of nitrate because of much oxygen produced during the aeration period; the intensity of nitrification was much stronger in the treatment of aeration than that in the treatment of non-aeration in constructed wetland; along the sampling points, the nitrification intensity was gradually reduced and the denitrification intensity was not changing so significantly compared to nitrification intensity. Compared with the treatment of aeration and non-aeration, the denitrification intensity was much stronger in the aeration conditon; in all constructed wetland used in this paper, denitrification intensity were significantly stronger than nitrification intensity, and aeration can improve the effect of denitrification and reduce the nitrification intensity at the same time.