The constructed wetland is an ecological sewage treatment with good removal effects and low construction and operation cost. However, the oxygen condition in constructed wetlands is of particularity and affect removal effects of wetlands. For the lack of systematical study on oxygen condition of wetlands, the further development of wetlands is disturbed to some extent. In this paper, horizontal flow wetlands with various kinds of plants grown were first studied on their operation characteristics and oxygen condition in treating the sewage out from the primary sedimentary basin. The rules of oxygen condition changed with space and time were studied. Researches showed the oxygen concentration was low in wetlands, and it appeared as a rule that low in both ends, but high in middle of beds. It descended in upright direction. The oxygen concentration changed with seasons as summer>spring>autumn>winter. In one day, the highest oxygen concentration appeared on 14:00, and tne concentration was higher in forenoon than afternoon. Reed>canna>camellia>dracaena sanderiana>ipomoea aquatica forsk by comparison of ability of oxygen supply. Experiments demonstrate that the study of oxygen condition in constructed wetlands is propitious to reveal the purifying mechanism of wetlands and improve the purifying efficiency. |