Intensifying Oxygen Supply Influence On Purifying Effect Of Constructed Wetlands

The constructed wetland is an ecological sewage treatment with good removal effects and low construction and operation cost. However, the pollutant removal efficiency of constructed wetland is greatly affected by such factors as dissolved oxygen, air temperature, wetland plants, microorganisms in soil, however these factors limit the further improving of purifying effect in wetland, now becoming the blocking bottleneck in extending application of wetland.Starting from the change of supplying oxygen condition, four intensifying measures such as aeration, circumfluence, three-point-water-inflow, link are put forward and then the optimal operation condition is determined. Purifying effect of wetlands in four operation conditions upwards is mainly studied.Researches show that aeration has greatly influence on purifying effect of constructed wetlands and makes the wetlands keep up removal efficiency at high level even in cold temperature, removal efficiency of COD and TP is above 60%, 45%. Place, intension and mode are main affecting factors of purifying effect when aerating. Researches on space-time distribution rules of dissolved oxygen show that: its concentration in the front of wetlands is more higher than that in the back, and the concentration in the middle is more higher than that in the upside and underside. Dissolved oxygen's concentration in whole one day maintain invariable, and its most fluctuating extend is only about 0.11 mg/L.The results of research demonstrate that circumfluence makes purifying effect of constructed wetlands improve obviously. Removal efficiency of various pollutants increases most quickly, such as removal efficiency of COD,TN,NH3-N and TP is respectively improved 20.2%,16.4%,17.5%,4.2% when the cycling rate is 1. Some changes of purifying effect of wetlands take place after adopting three-point-water-inflow. Purifying effect of wetlands is best when distributing water rate is 1:2:1,and removal efficiency of COD,TN,NH3-N and TP is respectively up to 87.9%,76.4%,81.3%,70.1%. After two constructed wetlands are connected their removal effects changes little, especially removal efficiency of some pollutants appears descending.The distribution rule of dissolved oxygen in wetlands is studied by suing the experiment achievements in the paper, and four intensifying measures are put forward, which has significant value in popularizing the application and development of wetlands in varying areas and conditions.